Powder Diffraction

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Apr 30, 2012 - Crystal structure and powder diffraction reference pattern of type I clathrate ... Powder Diffraction is a journal of practical technique, publishing ...
Powder Diffraction An International Journal of Materials Characterization

Volume 27 / Number 01 / March 2012

Volume 27 Number 1 March 2012 CODEN: PODIE2 ISSN: 0885-7156

EDITORIAL Nicole M. Ernst Boris

International Centre for Diffraction Data (ICDD) welcomes Cambridge University Press as its new publisher for Powder Diffraction

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Aleksandra Dapčević, Dejan Poleti, and Ljiljana Karanović

Improved structural model of Pb-doped γ-Bi2O3: (Bi23.68Pb0.32)(Bi1.28Pb0.72)O38.48

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A. Dominic Fortes, and Ian G. Wood

X-ray powder diffraction analysis of a new magnesium chromate hydrate, MgCrO4·11H2O

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Joannie Martin, Martin Beauparlant, Jacques Lesage, and Huu Van Tra

Development of a quantification method for quartz in various bulk materials by X-ray diffraction and the Rietveld method

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F. Needham, C. E. Crowder, J. W. Reid, T. G. Fawcett, and J. Faber

X-ray powder diffraction analysis of imipenem monohydrate

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W. Wong-Ng, Q. Huang, I. Levin, J. C. Woicik, X. Shi, Jihui Yang, and J. A. Kaduk

Crystal structure and powder diffraction reference pattern of type I clathrate Ba8Ni4Ge42

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TECHNICAL ARTICLES

NEW DIFFRACTION DATA A. Kheïreddine, M. Tridane, and S. Belaaouada

Chemical preparation and XRD data for four cyclotriphosphates: Ba3(P3O9)2·4H2O, BaNH4P3O9·2H2O, BaTlP3O9·2H2O, and BaTlP3O9·Ba3(P3O9)2·4H2O

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INTERNATIONAL REPORTS Julian Messick

The history of the International Centre for Diffraction Data

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T. N. Guru Row

ICDD PDF-4 Workshop

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James A. Kaduk

International Union of Crystallography (IUCr) XXII Congress, Madrid, August 22–30, 2011

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José Miguel Delgado

XX International Materials Research Conference

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Winnie Wong-Ng

The Materials Science & Technology 2011 Conference & Exhibition

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Calendar of Forthcoming Meetings

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Short Courses & Workshops

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Powder Diffraction notes for authors

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Cumulative Author Index

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CALENDAR

Editor-in-Chief Ting C. Huang Emeritus, IBM Almaden 9 Fl., #61 Sec. 1, Ao-Ho Road Taipei, Taiwan [email protected] Managing Editor Nicole M. Ernst Boris International Centre for Diffraction Data 12 Campus Boulevard Newtown Square, Pennsylvania 19073-3273, U.S.A. [email protected] Editor for New Diffraction Data W. Frank McClune International Centre for Diffraction Data 12 Campus Boulevard Newtown Square, Pennsylvania 19073-3273, U.S.A. [email protected] Editors Xiaolong Chen Institute of Physics Chinese Academy of Sciences No. 8 Nansanjie, Zhongguancun, Haidian District, Beijing 100190, China [email protected] José Miguel Delgado Universidad de Los Andes Facultad de Ciencias Departamento de Química Lab de Cristalografía Mérida 5101 Venezuela [email protected] Norberto Masciocchi Universitá dell’Insubria Dipartimento di Scienza e Alta Tecnologia via Valleggio 11 Como 22100 Italy [email protected] Ian Madsen CSIRO Minerals P.O. Box 312 Clayton South, Victoria 3169 Australia [email protected] Editors for Crystallography Education James Kaduk Analytical Science Research Services Poly Crystallography Inc. 423 East Chicago Avenue Naperville, Illinois 60540-5407, U.S.A. [email protected] Brian H. Toby Argonne National Laboratory Advanced Photon Source 9700 S. Cass Ave., Bldg. 433/D003, Argonne, Illinois 60439-4856, U.S.A. [email protected] International Reports Editor Winnie Wong-Ng National Institute of Standards and Technology 100 Bureau Drive, Mail Stop 8520 Gaithersburg, Maryland 20899-8520, U.S.A. [email protected] Calendar of Meetings and Workshops Editor Gang Wang Institute of Physics Chinese Academy of Sciences No. 8 Nansanjie, Zhongguancun, Haidian District, Beijing 100190, China [email protected] On the cover: The polyhedral presentation of (Bi23.68Pb0.32) (Bi1.28Pb0.72)O38.48 compound. (Courtesy of Aleksandra Dapčević, Dejan Poleti, and Ljiljana Karanović).

Powder Diffraction is a quarterly journal published by the JCPDS-International Centre for Diffraction Data through Cambridge University Press. Powder Diffraction is a journal of practical technique, publishing articles relating to the widest range of application—from materials analysis to epitactic growth of thin films and to the latest advances in software. Although practice will be emphasized, theory will not be neglected, especially as its discussion will relate to better understanding of technique. Submit manuscripts online at http://mc.manuscriptcentral.com/pdj. See the instructions on submitting your manuscript linked on that page. The editors will consider all manuscripts received, but assume no responsibility regarding them. There is no publication charge. Most proofs are handled via email at [email protected]. Proofs and all correspondence concerning papers in the process of publication can also be addressed to: Production Editor, Powder Diffraction, Cambridge University Press, 32 Avenue of the Americas, New York, NY 10013-2473, U.S.A. Please include the job number in all correspondence. For advertising rates and schedules contact Cambridge University Press Advertising Sales. Orders, advertising copy, and offset negatives should be sent to: Advertising Sales, Cambridge University Press, 32 Avenue of the Americas, New York, NY, 10013-2473, U.S.A.; Phone: 212-924-3900; Fax: 212-924-3900. Email: [email protected]. Subscription Prices 2012 Individual (U.S. & Canada) Individual (outside U.S. & Canada) Student Institutional or Library

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Subscription rates to Eastern Hemisphere include air freight service. Back-Number Prices. 2012 single copies: $62. Subscription, renewals, and address changes should be addressed to Subscription Fulfillment, Powder Diffraction, Cambridge University Press, 100 Brook Hill Drive, West Nyack, NY 10013-2113 (for U.S.A., Canada, and Mexico); or Cambridge University Press, The Edinburgh Building, Shaftsbury Road, Cambridge, CB2 8RU, Cambridge, England (for UK and elsewhere). Allow at least six weeks advance notice. For address changes please send both old and new addresses and, if possible, include a mailing label from the wrapper of a recent issue. Claims, Single Copy Replacement, Back Volumes, and Reprints: Missing issue requests will be honored only if received within six months of publication date (nine months for Australia and Asia). Single copies of a journal may be ordered and back volumes are available in print or microform. Individual subscribers please contact Subscription Fulfillment, Powder Diffraction, Cambridge University Press, 100 Brook Hill Drive, West Nyack, NY 10013-2113. Phone: 845-353-7500; Toll free: 800-872-7423; Fax: 845-353-4141. Email: [email protected]. Powder Diffraction (ISSN: 0885-7156) is published quarterly (4X annually) by the JCPDS-International Centre for Diffraction Data through Cambridge University Press, 32 Avenue of the Americas, New York, NY 10013-2473. POSTMASTER: Send address changes to Powder Diffraction, Cambridge University Press, 100 Brook Hill Drive West Nyack, NY 10994-2113, USA. Periodicals postage paid in New York, NY and additional mailing offices. Permission for Other Use: Permission is granted to quote from the journal with the customary acknowledgment of the source. To reprint a figure, table, or other excerpt requires the consent of one of the authors and notification to Cambridge University Press. Requests for Permission: No part of this publication may be reproduced in any forms or by any means, electronic, photocopying, or otherwise, without permission in writing from Cambridge University Press. Policies, request forms, and contacts are available at: http://journals.cambridge.org/action/rightsAndPermissions. Permission to copy (for users in the U.S.A.) is available from Copyright Clearance Center: http://www.copyright.com. Email: [email protected]. Document Delivery and Online Availability: Abstracts of journal articles published by Cambridge University Press are available from Cambridge Journals Online (http:// journals.cambridge.org/action/displayJournal?jid=PDJ). Copyright © 2012 JCPDS- International Centre for Diffraction Data, 12 Campus Blvd., Newtown Square, PA 19073-3273, U.S.A. All rights reserved. www.icdd. com/products/journals.htm

EDITORIAL International Centre for Diffraction Data (ICDD) welcomes Cambridge University Press as its new publisher for Powder Diffraction ICDD is very pleased to announce that Cambridge University Press is publishing Powder Diffraction. Cambridge now provides copy editing, production, subscription, hosting, and printing services. ICDD will continue to be responsible for the editorial content of the journal utilizing the staff as listed on our masthead. Cambridge University Press has a long history of publishing, and publishes the MRS Bulletin, Microscopy Today, and nearly 300 other journals. We are confident that Cambridge University Press will provide Powder Diffraction an appealing venue in which to grow. Cambridge University Press publishes over 280 peerreviewed academic journals in a wide variety of subject areas. Their history begins under Henry VIII when in 1534 he granted them letters patent, allowing them to print “all manner of books”. They published their first book in 1584, making them the oldest university press in the world. Their reputation grew over the next 400 years based on excellence in scholarly publishing (i.e. academic texts, poetry, and school books) and

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Powder Diffraction 27 (1), March 2012

published such ground-breaking works such as Newton’s Principia Mathematica, Milton’s Lycidas, Rutherford’s Radio-activity, and Chomsky’s Language and Mind. They now have over 50 offices across the globe and publish over 40 000 titles by authors from over 100 countries. Powder Diffraction’s content is now part of Cambridge’s online platform, Cambridge Journals Online (CJO), and we expect to have online content available back to 1986 by the end of 2012. The online issues are more dynamic and feature the ability to “flip” through journal pages like a paper copy, while maintaining the dynamics of html. Users will now use the ScholarOne online peer review and manuscript submission platform to submit manuscripts to Powder Diffraction. We look forward to a mutually beneficial relationship with Cambridge University Press!

0885-7156/2012/27(1)/1/1/$18.00

Nicole M. Ernst Boris Managing Editor, Powder Diffraction

© 2012 JCPDS-ICDD

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Improved structural model of Pb-doped γ-Bi2O3: (Bi23.68Pb0.32)(Bi1.28Pb0.72)O38.48 Aleksandra Dapčević,1,a) Dejan Poleti,1 and Ljiljana Karanović2 1

Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia Faculty of Mining and Geology, University of Belgrade, --Dušina 7, 11000 Belgrade, Serbia

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(Received 26 December 2011; accepted 29 December 2011) A polycrystalline single-phase sample with nominal composition Bi24PbO37 was synthesized from Bi2O3 and PbO by a high-temperature solid state reaction at 690 °C for 1.5 h. The compound adopts Bi12SiO20-type structure [cubic, space group I23 (No. 197); a = 10.24957(3) Å] and was refined to Rp = 7.96%, Rwp = 10.4%, Rexp = 8.43%, RB = 3.06%, and S = 1.23. The distributions of Pb2+ and Bi3+ over cationic sites based on the X-ray powder diffraction data were determined using a combination of the Rietveld refinement and bond valence calculations. The results showed that the asymmetric unit contains two mixed cation sites: the fully occupied 24f site and the partly occupied 8c site, with the unit-cell content (Bi23.68Pb0.32)(Bi1.28Pb0.72)O38.48. The structural constraints favor a preference of Pb2+ ion for the 8c site, i.e. only 1.3% of Bi3+ is substituted by Pb2+ at the 24f site and 36% at the 8c site. At the 24f site, the cations are surrounded by 5 + 2 or in a very small amount by 5 + 1 + 2 oxide ions, forming a base bicapped square pyramid or a bicapped highly deformed octahedron, respectively. At the 8c site, the cations with three oxide ions form a trigonal pyramid with the cations at the apex. © 2012 International Centre for Diffraction Data. [doi:10.1017/S0885715612000073] Key words: Bi24PbO37, sillenite, crystal structure, Rietveld refinement, bond valence, mixed sites

I. INTRODUCTION

Bismith(III) oxide exhibits an extraordinary rich phase polymorphism appearing in seven modifications: monoclinic α-, tetragonal β-, body-centered cubic γ-, face-centered cubic δ-, orthorhombic ε-, triclinic ω-, and a high-pressure hexagonal phase (Sillén, 1937; Gattow and Schröder, 1962; Levin and Roth, 1964a; Harwig, 1978; Harwig and Weenk, 1978; Harwig and Gerards, 1979; Gualtieri et al., 1997; Sammes et al., 1999; Cornei et al., 2006; Ghedia, et al., 2010). Among these seven polymorphisms, metastable γ- and hightemperature δ-Bi2O3 are found to be the most investigated because of their interesting structural and other properties. The high-temperature δ-Bi2O3 modification can be stabilized at room temperature by using many isovalent and aliovalent cations to substitute Bi3+ (Shuk et al., 1996; Sammes et al., 1999), but this often causes the formation of modulated structures based on a fluorite-related substructure (Watanabe, 1997; Pang et al., 1998; Darriet et al., 2005). The metastable γ-Bi2O3 phase can also be stabilized down to room temperature by doping with many different cations, and in that case the structural features depend on the size, oxidation state, and concentration of dopant (Levin and Roth, 1964b). The title compound is one of the doped γ-Bi2O3 phases belonging to the Bi12SiO20 (sillenite) structure type. There are two cation sites in this structure: general 24f and special 2a. The cation, labeled as Bi1, is positioned at the 24f site, while the dopant cation, M, is positioned at the 2a site, i.e. in the origin and center of the bcc unit cell (space group I23). As long as the charge of dopant is 4 + , the crystal structure is composed of Bi1O7 polyhedra and ideal MO4 a)

Author to whom correspondence should be addressed. Electronic mail: [email protected] 2

Powder Diffraction 27 (1), March 2012

tetrahedra. Five oxygen atoms at shorter distances form a distorted square pyramid, and with two other oxygen atoms at very long distances create a 5 + 2 coordination polyhedron around Bi1. According to bond valence (BV) calculations (Poleti et al., 2007), the contribution of two distant oxygen atoms to the bond valence sum of Bi13+ ion is negligible (usually 20 wt% Test IV

Scale factor (S) Specimen displacement Lattice parameters W (half-width) Peak parameter

All phases All phases >20 wt% >20 wt%

complicate the analysis, and this is not desirable because time is an important criterion. As the primary aim of the study was to develop an automated refinement procedure, several different routines were tested on the 19 samples. In total, 18 different routines were tested, but only four have been presented here. Table V gives details of the refinement steps for the different routines presented. The first parameter refined, the scale factor, represents the relative intensity of a phase (Snyder, 1992). By definition, the measured intensity of the strongest line of each phase should be used to calculate the scale factor, but in the software used (X’Pert HighScore), it is determined by a least-squares fit

Figure 1. (Color online) Comparison of the diffraction patterns obtained in the analysis of a polycrystalline sample containing 0.83 wt% quartz with Soller slits of 0.02 and 0.04 rad. 16

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Martin et al.

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through all matching reference pattern lines. This should help counteract texture effects to some extent, but does not exactly follow the original definition. Specimen displacement is another important parameter in the refinement process. It can be caused either by a misalignment of the goniometer or by an uneven sample surface. It results in a change in the measured value of d and a decrease in the diffraction intensity (Hurst et al., 1997). The lattice parameters were also refined in the suggested procedure. As almost all the samples encountered contained only well-known phases, the variation in lattice parameters was not really large but still had a non-negligible impact on the quantitative results. A large amount of natural material was analyzed and the lattice parameters were different for the same phase from different samples. An important parameter of the ray profile is the width at mid-height. In general, this parameter increases with the angle, and, most of the time, this evolution can be described by a tan θ second-degree polynomial (Caglioti polynomial) (Caglioti et al., 1958). In a Rietveld refinement, parameters U, V, and W are refinable. They vary in relation to the instrument’s resolution and according to the microstructural characteristics of the analyzed sample (Guinebretière, 2006). The instrument’s contribution to the value of these parameters can be determined if a very high quality pattern is used for the calibration. The sample’s contribution can then be calculated by the refinement. Refining all these three values at the same time makes the refinement unstable. In the case of an automatic refinement, only one is refined, namely W. Its impact on fit is more important than that of the other two, so the integrated area is a better evaluation for quantification, even if the value determined cannot be logically interpreted without further refinement of U and V parameters. These 18 different routines were tested by including and excluding background noise refinement. In all cases, the average absolute error was greater but all the quality indices were better. For this reason, the chosen procedure does not include background noise refinement, and thus the quantifications obtained are more accurate and the quality indices reflect the quality of the model by being less influenced by a large number of parameters. Table VI shows that test III and IV routines gave very similar results, and test IV allowed visual observation of a great similarity between the diffraction pattern and the model; thus, we used this refinement procedure for our method. No correction was applied for microabsorption or extinction because the size of the particles in the sample must be known precisely for these corrections to improve the model; otherwise, it could worsen the result (Madsen et al., 2001).

Thus, a general milling procedure described before was established to achieve a particle size that reduces to a minimum the effects of microabsorption and extinction. As several phases are generally present in the samples, it is normal to expect a larger distribution of particle sizes than for samples containing only one phase.

Table VI. Average absolute error in the quantification of quartz in relation to the applied refinement routinesa and agreement indices.

Table VII. Calculated limit of detection (LOD) for the three most intense diffraction peaks of quartz.

Routine

Absolute error (wt%)

R1 (mean)

wR2 (mean)

Test I Test II Test III Test IV

1.42 1.16 1.06 1.07

8.47 10.93 8.97 8.60

10.97 14.28 11.57 11.20

a

The absolute error presented and the average of the absolute errors calculated on 19 samples with the 0.4-rad Soller slit. 17

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B. Limit of detection

To ensure the applicability of the method, the limit of detection (LOD) was studied. A literature review rapidly determined that there is no standard way to calculate the LOD in X-ray diffraction. It is generally taken for granted that an LOD of 0.1 wt% is achieved for bulk samples that are free of interference. However, it is impossible for our method to make this assumption because of the large variety of matrixes encountered and the major possibility of interference at one of the planes of quartz. Two methods were therefore used to attempt to evaluate the LOD. The first method is the one proposed by Jenkins and Snyder (1996). The equation below defines the net counting error (n), where Np is the integrated intensity of the peak and background and Nb is the background intensity.  ⎡ 1/2 ⎤ 100 Np + Nb ⎣s(n) = ⎦. (1) N p − Nb The lower detection limit 2σ (95% probability) was calculated with 19 samples using the data of the three most intense diffraction peaks: (101) d = 3.342 Å, (100) d = 4.257 Å, and (112) d = 1.8179 Å. The results obtained, showed in Table VII, take into account only the quality of the acquired diffraction pattern and the intensity of the planes used; they do not consider pattern treatment and the application of Rietveld refinement using the complete diffraction pattern. They therefore indicate the sensitivity of the instrumentation used. However, these calculations made it possible to observe that the LOD was greatly increased in samples containing more than 80 wt% amorphous materials, which is reasonable, considering the significant increase in the background noise signal in this type of sample, causing a major reduction in the signal/noise ratio. To take into account the entire procedure applied to the sample to quantify it, another method for calculating the LOD was used. The method used by Német et al. (2010) was reproduced with our samples. Two samples containing close to 1 wt% quartz were used. The general method consists of taking a sample containing a quantity of the compound that is assumed to be close to the

Plane (101) (100)a (112)a Average

I rel (%)

LOD (wt%)

100 21 12

0.24 3.50 4.12 2.62

a

Only 18 samples were used for these calculations because the last one was not sufficiently concentrated for these planes to be detected. Development of a quantification method for quartz

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Table VIII. Limit of detection (LOD) and limit of quantification (LOQ) calculated for the complete method on samples A and B. Sample

LOD (wt%)

LOQ (wt%)

A B Average

0.259 0.210 0.235

0.786 0.637 0.711

because it does not apply to all types of samples. Problematic samples must be studied further to allow their analysis to be accurate as well as simple and rapid. When this problem will be overcome, more testing of natural field samples will need to be done to evaluate the impact of the microstructural default of quartz in quantification. ACKNOWLEDGMENTS

LOD value, which is then quantified seven times by repeating each of the steps in the method every time. The standard deviation between the values obtained is then used to calculate the LOD by multiplying the standard deviation by 3.3 and by 10 to obtain the limit of quantification. This calculation uses the quantification values found by the application of the Rietveld method, thus including the intensities of the complete pattern. The calculation was done with a sample (E12) containing two crystalline phases and one amorphous phase, with 0.94 wt% quartz and 89.13 wt% amorphous phase, and another sample (E14) containing five crystalline phases and one amorphous phase, with 0.83 wt% quartz and 6.08 wt% amorphous phase. The samples were removed between acquisitions, remixed, and then remounted in the specimen holders. The background noise was determined for each of the patterns to calculate the variations caused by the experimenter. This calculation technique seems to be more representative of the actual sensitivity of the developed method as it includes all the analytical steps, particularly the Rietveld refinement. The results obtained, as shown in Table VIII, make it possible to state that samples of concentrations of 1.0 wt% quartz or more can be detected and quantified with the proposed method and the instrumentation used. IV. CONCLUSION

The development of this quantitative analysis method and the evaluation of its limits have led to several conclusions. The method respects the criteria needed for a routine analysis, namely being simple, rapid, and easy to execute. The quartz in simulated matrixes containing 0.1–82.0 wt% quartz could be determined with a good accuracy in matrixes of variable composition. The limits of detection and quantification calculated for the entire method are encouraging with regard to the possibility of obtaining a reliable result for samples of low concentration. However, certain limitations are proposed by this study, including mainly the impossibility of analyzing samples presenting an important phenomenon of microabsorption, consisting of one or more crystalline phases of unknown structures, or containing more than a dozen crystalline phases. For samples presenting any of these characteristics, a more thorough analysis becomes necessary, and systematic automation is impossible. Although the Rietveld method was simplified as much as possible for this procedure, it is still important that it be used by an experimenter who can detect inconsistent results for the phases present, interpret the quality indicators (Rp, Rwp, and Goof) correctly, and develop an appropriate initial model for each of the patterns encountered. As these limits are clearly identified, it becomes possible to perform an automated Rietveld analysis on majority of the samples encountered. The method developed in this study can be useful in certain cases but the primary objective is not totally achieved 18

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The authors thank the Association Québecoise pour l’Hygiène, la Santé et la Sécurité du Travail (AQHSST); Claudette Dufresne, Catheline Pelletier, and Sébastien Gagné of Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) for the technical support and good advice; PANalytical application specialists Dr. Jennifer Anderson, Dr. Thomas Dortmann, and Dr. Thomas Degen; Dr. Gilles L’espérance and all the members of the Centre for Characterization and Microscopy of Material, the CM2 de l’École Polytechnique de Montréal; Dr. Joel Reid of ICDD; Dr. Thomas N. Blanton of the Eastman Kodak Company; Dr. Susan Quick of Pennsylvania State University; and all the Rietvelders for their invaluable help and advice. Asahi, T., Matsudaira, T., Kobayashi, S., Nakayama, K., and Nakamura, T. (2010). “Estimation of purity of chrysotile asbestos by X-ray diffractometry/rietveld refinement,” Analyt. Sci. 26(12), 1295–1300. Bish, D. L. and Post, J. E. (1989). Modern Powder Diffraction (Mineralogical Society of America, Washington DC). Bish, D. L. and Post, J. E. (1993). “Quantitative mineralogical analysis using the Rietveld full-pattern fitting method,” Am. Mineral. 78, 932–940. Caglioti, G., Paoletti, A., and Ricci, F. P. (1958). “Choice of collimators for a crystal spectrometer for neutron diffraction,” Nucl. Instrum. 3(4), 223–228. Cline, J. P. (1992). “NIST XRD standard reference materials: their characterization and uses” Proceedings of the International Conference on Accuracy in Powder Diffraction II, NIST Special Publication 846 (U.S. Government Printing Office, Washington DC). De La Torre, A. G., Bruque, S., and Aranda, M. A. G. (2001). “Rietveld quantitative amorphous content analysis,” J. Appl. Crystallogr. 34(2), 196– 202. Gonzalez, R. M., Lorbieke, T. D., McIntyre, B. W., Cathcart, J. D., Brownfield, M., and Winburn, R. S. (2002). “Factors influencing quantitative results for coal combustion by-products using the Riestveld method,” Adv. X-ray Anal. 45, 188–193. Guinebretière, R. (2006). Diffraction des rayons X sur échantillons polycristallins (Hermes, Paris). Guirado, F., Galí, S., and Chinchón, S. (2000). “Quantitative Rietveld analysis of aluminous cement clinker phases,” Cement Concrete Res. 30(7), 1023– 1029. Hurst, V. J., Schroeder, P. A., and Styron, R. W. (1997). “Accurate quantification of quartz and other phases by powder X-ray diffractometry,” Anal. Chim. Acta 337(3), 233–252. Jenkins, R., Fawcett, T. G., Smith, D. K., Visser, J. W., Morris, M. C., and Frevel, M. K. (1986). “JCPDS-International Center for Diffraction, Data sample preparation methods in X-ray powder diffraction,” Powder Diffr. 1(2), 51–63. Jenkins, R. and Snyder, R. L. (1996). Introduction to X-ray Powder Diffractometry (John Wiley & Sons, Inc., New York). Madsen, I. C., Scarlett, N. V. Y., Cranswick, L. M. D., and Lwin, T. (2001). “Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: samples 1a to 1 h,” J. Appl. Crystallogr. 34(4), 409–426. Miles, W. J. (1999). “Issues and controversy: the measurement of crystalline silica; review papers on analytical methods,” Am. Ind. Hyg. Assoc. J. 60, 396–402. Német, Z., Sajó, I., and Demeter, A. (2010). “Rietveld refinement in the routine quantitative analysis of famotidine polymorphs,” J. Pharm. Biomed. Anal. 51(3), 572–576. Martin et al.

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RoHS, Québec (2011). Regulation respecting Occupational Health and Safety (S-2.1, r.13, G. D. Québec) (Restriction of Hazardous Substances, Québec). Schwarz, M. I. and King, T. E. J. (2009). Interstitial Lung Disease (People’s Medical Publishing House, Beijing). Smith, D. K. (1997). “Evaluation of the detectability and quantification of respirable crystalline silica by X-ray powder diffraction methods,” Powder Diffr. 12(4), 200–227.

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Snyder, R. L. (1992). “The use of reference intensity ratios in X-ray quantitative analysis,” Powder Diffr. 7(4), 186–193. Till, R. and Spears, D. A. (1969). “The determination of quartz in sedimentary rocks using an X-ray diffraction method,” Clays Clay Miner. 17(5), 323– 327. Winburn, R. S., Grier, D. G., McCarthy, G. J., and Peterson, R. B. (2000). “Rietveld quantitiative X-ray diffraction analysis of NIST fly ash standard reference materials,” Powder Diffr. 15(3), 163–172.

Development of a quantification method for quartz

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X-ray powder diffraction analysis of imipenem monohydrate F. Needham,a) C. E. Crowder, J. W. Reid, T. G. Fawcett, and J. Faber International Centre for Diffraction Data, 12 Campus Boulevard, Pennsylvania 19073

(Received 20 October 2011; accepted 9 December 2011) An experimental X-ray powder diffraction pattern was produced and analyzed for imipenem monohydrate, an antimicrobial pharmaceutical agent. Although there are no experimental powder patterns in the ICDD PDF-4/Organics Database, there is one powder pattern calculated with single-crystal X-ray diffraction data from the Cambridge Structural Database. Here, we report the refined experimental powder diffraction data for imipenem monohydrate. These data for imipenem monohydrate are consistent with an orthorhombic crystal system having reduced unit-cell parameters of a = 8.2534(3) Å, b = 11.1293(4) Å, and c = 15.4609(6) Å. The resulting unit-cell volume, 1420.15(15) Å3, indicates four formula units per unit cell. Observed peaks are consistent with the P212121 space group. © 2012 International Centre for Diffraction Data. [doi:10.1017/S0885715612000048] Key words: imipenem, C12H17N3O4S, X-ray powder diffraction, β-lactam, hydrogen bonding

I. INTRODUCTION

Imipenem monohydrate, C12H17N3O4S·H2O [6-(1hydroxyethyl)-3-(2-(iminiomethylamino)ethylthio)-7-oxo-1azabicyclo(3.2.0)hept-2-ene-2-carboxylate monohydrate] (Figure 1), has been used with cilastatin sodium as an antimicrobial injection. Imipenem monohydrate, such as penicillin, belongs to the β-lactam antibiotic class and is often used as a last resort in place of other antibiotics with similar pharmaceutical functions. The chemical structure of imipenem monohydrate, unlike penicillin and many other β-lactam antibiotics, has no sulfur in the five-membered ring fused to the β-lactam ring, and contains a double bond in this same five-membered ring. Despite the restricted use of β-lactam antibiotics as a result of the discovery of β-lactam-resistant bacteria, imipenem monohydrate has a broad application against a variety of bacteria. Rietveld refinement of the imipenem monohydrate powder data confirmed an orthorhombic crystal system and a P212121 space group. The molecular structure (Figure 1) includes a number of electronegative atoms, such as oxygen, nitrogen, and sulfur, in the forms of carboxyl, hydroxyl, imino, amino, and sulfide groups. The crystal structure also includes water, which contributes to intramolecular and intermolecular hydrogen bonding. This hydrogen-bonding network contributes greatly to the crystal packing arrangement. There have been few studies of this compound and only one concerning a single-crystal form (Ratcliffe et al., 1989). However, its experimental powder data have not been explored. The PDF-4/ Organics 2012 Database (ICDD, 2011) contains one powder pattern calculated from the single-crystal data (Needham et al., 2003). Here, we report our findings on the imipenem monohydrate experimental X-ray powder diffraction pattern.

PANalytical PW1817/32 zero-background plate (obliquely cut silicon crystal) in a PANalytical PW1813/32 plate holder. The X-ray powder diffraction data were collected on a PANalytical X’Pert PRO system equipped with a copper X-ray source tube and an X’Celerator Detector. The scan range was 7–60° 2θ with a step size of 0.0167° 2θ. Two 0.02-rad Soller slits (for both incident and diffracted beams) were used to minimize the axial divergence aberration in the diffraction pattern. A 0.020-mm nickel filter was used to absorb CuKβ radiation and a 0.125° antiscatter slit was used to reduce background. The experimental conditions are listed in Table I. The powder pattern is presented in Figure 2. This procedure with a zero-background holder gave a very good texture index of 1.03 after refinement, indicating very little preferred orientation. III. RESULTS AND DISCUSSION

Analysis of the powder diffraction data was accomplished using PANalytical HighScore Plus (Needham et al., 2006).

Figure 1. Structural formula of imipenem monohydrate.

Table I. XRD data collection conditions for imipenem monohydrate.

II. EXPERIMENTAL

Imipenem monohydrate, purchased from United States Pharmacopeia (98–101% purity), was gently ground with an agate mortar and pestle. The powder was dusted on to a a)

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Powder Diffraction 27 (1), March 2012

Diffractometer

PANalytical X’Pert-PRO

Divergence slits (°) Radiation Power Detector Scan step size (°2θ) Sample rotation time (s)

0.0625 X-ray, CuKα1/Kα2 45 kV, 40 mA X’Celerator 0.0167 4

0885-7156/2012/27(1)/20/5/$18.00

© 2012 JCPDS-ICDD

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Figure 2. X-ray powder diffraction pattern for imipenem monohydrate. a = 8.2534(3) Å, b = 11.1293(4) Å, c = 15.4609(6) Å, Rp = 2.68%, WRp = 4.03%, and χ2 = 3.883.

Background subtraction and Kα2 removal were performed before determining the location of the diffraction peaks. The extensive overlapping strong peaks below 35° 2θ makes peak search a challenging task. HighScore Plus

(PANalytical, 2011) was used to find peaks. SQLAids (Sagnella, 2011) was used to evaluate the accuracy of these peak positions relative to the proposed orthorhombic cell. Results are shown in Table II. Rietveld refinement of the

Table II. XRD data for imipenem monohydrate. h

k

l

2θcal (°)

2θobs (°)

Δ2θ (°)

dobs (Å)

l/lmax

0 0 1 0 1 1 0 1 0 0 1 1 2 1 2 1 2 0 0 2 0 2 1 2 1 0 1 2 1 2 1 2 2 0 1 1 1 2 0

1 0 0 1 1 0 2 1 1 2 2 0 0 1 0 2 1 0 2 1 1 0 0 1 2 3 1 2 3 0 3 1 2 1 2 0 1 2 4

1 2 1 2 1 2 0 2 3 2 1 3 0 3 1 2 0 4 3 1 4 2 4 2 3 2 4 0 1 3 2 3 2 5 4 5 5 3 0

9.7840 11.437 12.146 13.937 14.526 15.694 15.914 17.610 18.961 19.641 20.067 20.299 21.516 21.826 22.279 22.423 22.967 22.991 23.509 23.685 24.358 24.432 25.425 25.727 25.898 26.631 26.675 26.876 26.952 27.670 28.778 28.830 29.293 29.968 30.138 30.855 31.910 32.080 32.145

9.7820 11.432 12.131 13.926 14.517 15.701 15.906 17.605 18.973 19.623 20.050 20.278 21.523 21.819 22.276 22.410 22.958 23.001 23.498 23.668 24.355 24.441 25.418 25.719 25.879 26.616 26.665 26.865 26.973 27.661 28.791 28.808 29.281 29.980 30.120 30.843 31.894 32.100 32.125

0.002 0.005 0.015 0.011 0.009 −0.007 0.008 0.005 −0.012 0.018 0.017 0.021 −0.007 0.007 0.003 0.013 0.009 −0.010 0.011 0.017 0.003 −0.009 0.007 0.008 0.019 0.015 0.010 0.011 −0.021 0.009 −0.013 0.022 0.012 −0.012 0.018 0.012 0.016 −0.020 0.020

9.0347 7.7341 7.2900 6.3541 6.0967 5.6396 5.5673 5.0337 4.6737 4.5203 4.4250 4.3758 4.1254 4.0701 3.9876 3.9641 3.8707 3.8635 3.7829 3.7562 3.6517 3.6391 3.5014 3.4611 3.4400 3.3464 3.3404 3.3160 3.3029 3.2223 3.0984 3.0966 3.0476 2.9781 2.9646 2.8968 2.8037 2.7861 2.7840

100 39 3 8 4 9 7 46 19 6 10 2 64 43 79 31 60 2 15 19 9 75 13 20 25 6 14 31 46 3 22 7 3 8 4 6 8 4 3 Continued

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X-ray powder diffraction analysis of imipenem monohydrate

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Table II. Continued h

k

l

2θcal (°)

2θobs (°)

Δ2θ (°)

dobs (Å)

l/lmax

0 2 2 3 3 1 3 0 1 2 3 1 2 0 3 2 1 1 0 1 1 2 1 2 1 2 1 4 2 4 1 4 4 0 4 2 0

4 1 3 0 1 4 1 4 4 3 0 2 2 1 2 1 1 4 2 3 2 3 5 1 5 4 5 0 2 1 2 1 2 3 2 2 6

1 4 1 1 0 0 1 2 1 2 2 5 4 6 1 5 6 3 6 5 6 4 0 6 1 3 2 1 6 1 7 2 0 7 2 7 2

32.676 32.722 32.953 33.045 33.527 33.975 34.038 34.224 34.481 34.490 34.579 34.901 35.654 35.738 36.878 37.192 37.413 38.316 38.468 39.445 40.046 40.124 42.008 42.097 42.431 42.917 43.681 44.251 44.499 45.032 45.493 46.226 46.927 47.894 48.465 49.554 50.563

32.655 32.706 32.936 33.054 33.517 33.987 34.019 34.219 34.475 34.481 34.580 34.887 35.632 35.721 36.876 37.199 37.421 38.295 38.456 39.427 40.058 40.113 41.991 42.072 42.415 42.908 43.676 44.244 44.483 45.019 45.503 46.214 46.915 47.882 48.453 49.537 50.571

0.021 0.016 0.017 −0.009 0.010 −0.012 0.019 0.005 0.006 0.009 −0.001 0.014 0.022 0.017 0.002 −0.007 −0.008 0.021 0.012 0.018 −0.012 0.011 0.017 0.025 0.016 0.009 0.005 0.007 0.016 0.013 −0.010 0.012 0.012 0.012 0.012 0.017 −0.008

2.7400 2.7359 2.7173 2.7079 2.6715 2.6356 2.6332 2.6183 2.5994 2.5990 2.5918 2.5697 2.5176 2.5116 2.4355 2.4151 2.4013 2.3485 2.3390 2.2836 2.2491 2.2461 2.1499 2.1460 2.1294 2.1061 2.0708 2.0455 2.0351 2.0121 1.9918 1.9628 1.9351 1.8982 1.8772 1.8386 1.8034

4 4 5 7 10 5 5 2 3 5 3 21 7 5 4 4 2 4 3 4 5 3 4 5 10 5 2 4 2 3 5 3 2 2 3 2 2

λ = 1.5406 Å and I/Imax are based on peak height

powder data was performed using GSAS (Von Dreele and Larson, 2001). The refinement parameters used were Chebyshev polynomial background, scaling, sample displacement, peak asymmetry, peak shape profiles (Gaussian and Lorentzian), Uiso temperature factors, unit-cell parameters, and atomic coordinates. The results are shown in Figure 2, with final refinement statistics of Rp = 2.68%, wRp = 4.03%, and χ2 = 3.883 (Figure 2). The refined unit-cell parameters are a = 8.2534(3), b = 11.1293(4), and c = 15.4609(6) Å. These vary from the reported values [a = 8.268(3), b = 11.140(6), and c = 15.452(9) Å] of single-crystal data in the PDF-4/Organics 2012 (Ratcliffe et al., 1989) by −0.18, −0.14, and 0.06%, respectively. One value of Uiso was used for refinement. The resulting refined Uiso value is 0.0893. The refined atomic coordinates are listed in Table III. Table IV lists three possible hydrogen bonds in addition to the water hydrogen bonds (Figure 3). Hydrogen bonds are shown as dotted lines in Figure 3. Two are intermolecular (N3/O2 and N3/O3) and one is intramolecular (O3/S1). Although the O3/S1 bonding distance is large and the sulfur atom has relatively weak electronegativity, the intramolecular proximity of the sulfur atom and hydroxyl hydrogen atom, and the resulting six-membered ring configuration makes its 22

Powder Diffr., Vol. 27, No. 1, March 2012

Table III. Atomic coordinates of imipenem monohydrate.a Atom

x

y

z

N1 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 O1 O2 S1 O3 O4 N2 N3 O5

0.1279(27) 0.1186(27) 0.0712(32) 0.0688(32) 0.1510(4) −0.0048(33) 0.0080(4) 0.0581(4) −0.0687(27) 0.1104(32) 0.0462(21) −0.0130(35) −0.3060(4) −0.0849(23) 0.0710(17) 0.0292(8) 0.0771(22) 0.1622(4) −0.1870(30) −0.2148(27) 0.3144(16)

0.8145(31) 0.6954(31) 0.6533(18) 0.7594(24) 0.8681(20) 0.9502(19) 0.8977(24) 1.0862(25) 1.1790(19) 0.6341(5) 0.5220(30) 0.3965(20) 0.2680(31) 0.9105(15) 1.1261(12) 0.5044(7) 0.5197(17) 0.7041(34) 0.3754(19) 0.1786(22) 0.0946(13)

−0.0628(16) −0.0736(17) 0.0118(18) 0.0889(16) 0.0319(20) 0.0078(17) −0.0855(22) 0.0055(19) −0.0431(14) −0.1749(22) 0.1559(19) 0.2012(13) 0.2048(16) −0.1561(14) 0.0973(11) 0.0465(4) −0.1405(9) −0.2103(24) 0.2063(11) 0.1778(15) 0.2084(10)

a

Uiso value is 0.0893. Needham et al.

22

Table IV. Hydrogen-bonding lengths in imipenem monohydrate. Atom 1

Atom 2

Length reported in this study (Å)

Length reported by Ratcliffe et al. (1989) (Å)

O5 O5 O5 O5 N3 N3 O3

N2 O2 O3 O4 O2 O3 S1

2.90(2) 2.67(2) 2.72(2) 2.72(2) 2.80(2) 2.81(3) 2.92(1)

2.84 2.68 2.72 2.79 2.86 2.79 2.89

hydrogen bonding a very strong possibility. The water is hydrogen bonded to four molecules and the hydrogenbonding length of water (Table IV) is similar to those of the reported values (Ratcliffe et al., 1989). The O5/O2 and O5/ O3 water hydrogen bonds are responsible for the head to tail packing of the fused rings of two adjacent molecules. Also, the O5/N2 and O5/O4 hydrogen bonds are orthogonal to the O5/O2 and O5/O3 bonds. The O5/O2 and O5/O3 hydrogen

Figure 3.

23

bonds are responsible for the arrangement of fused rings in a paralleled stacking fashion. The tetrahedral-like hydrogen bonding of the water molecule causes the stacking of fused rings in alternating fashion and hence forms a threedimensional hydrogen-bonding network. The moderately long side chain with single bonds has a moderate amount of rotational freedom, which contributes to the conformational difference. The experimental unit cell is smaller than that derived from single-crystal data. The dusted powder samples on the zero-background plate minimized the preferred orientation effect. The thin layer of the experimental sample reduced the transparency aberration of the compound consisting of light elements. Finally, the zero-background sample holder minimized the background interference of the data analysis. The combination of all the advantages of the zerobackground method for the imipenem monohydrate powder diffraction experiment enabled the successful resolution of overlapping peaks at low diffraction angles. This conclusion is supported by the more successful Rietveld refinement analysis as compared to other explored methods.

(Color online) Crystal structure of imipenem monohydrate.

Powder Diffr., Vol. 27, No. 1, March 2012

X-ray powder diffraction analysis of imipenem monohydrate

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ACKNOWLEDGMENTS

The XRD data reported in our study were collected from an X-ray powder diffractometer supplied by PANalytical USA during ICDD clinics. We thank the generosity of PANalytical USA for making the instrument available for us to conduct experiments. ICDD (2011). PDF-4/Organics 2012 Database, edited by S. Kabekkodu, International Centre for Diffraction Data, Newtown Square, Pennsylvania, USA. Needham, F., Faber, J., and Fawcett, T. (2006). “X-ray powder diffraction analysis of tegafur,” Powder Diffr. J. 21(3), 245–247.

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Needham, F. and Faber, J. (2003). “Total pattern analysis using the new organic powder diffraction file: PDF-4/Organics,” Am. Pharm. Rev. 6(4), 10–12. PANalytical (2011). HighScore Plus, Version 3.0.3 (Computer Software), PANalytical, Netherlands. Ratcliffe, R., Wildonger, K., Michele, L., Douglas, A., Hajdu, R., Goegelman, R., Springer, J., and Hirshfield, J. (1989). “Studies on the structures of imipenem, dehydropeptidase I hydrolyzed imipenem, and related analogues,” J. Org. Chem. 54, 653–660. Sagnella, D. (2011). SQLAids (Computer Software), International Centre for Diffraction Data, Newtown Square, Pennsylvania, USA. Von Dreele, R. and Larson, A. (2001). General Structure Analysis System (GSAS, Computer Software), University of California, USA.

Needham et al.

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Crystal structure and powder diffraction reference pattern of type I clathrate Ba8Ni4Ge42 W. Wong-Ng,1,a) Q. Huang,1 I. Levin,1 J. C. Woicik,1 X. Shi,2 Jihui Yang,2 and J. A. Kaduk3 1

National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899 Materials and Processes Laboratory, General Motors R&D Center, Warren, Michigan 48090 3 Poly Crystallography, Inc., Naperville, Illinois 60540-5407 2

(Received 6 September 2011; accepted 29 September 2011) The crystal structure of type I clathrate Ba8Ni4Ge42 has been determined using neutron powder diffraction, transmission electron microscopy (TEM, for possible superlattice), and extended X-ray absorption fine structure (EXAFS) measurements. Ba8Ni4Ge42 is cubic with the space group Pm3n and unit-cell parameter a = 10.6769(2) Å (Dx = 5.988 g cm−3). The structure combines two different types of polyhedra: the dodecahedron (Ge20, 20-atom cage with 12 pentagonal faces) and the tetrakaidecahedron (Ge24, 24-atom cage with 12 pentagonal and 2 hexagonal faces). Each unit cell contains two Ge20 dodecahedra and six Ge24 tetrakaidecahedra. The Ge20 dodecahedra are linked via the interstitial 6c positions. The framework structure is formed by a tetrahedrally bounded network of Ge atoms, whereas Ba atoms reside inside the Ge20 and Ge24 cavities at the 2a and 6d crystallographic positions, respectively. Ni atoms exclusively occupy the 6c positions located on the hexagonal faces of the larger tetrakaidecahedra; no Ni atoms are found in the smaller dodecahedra that consist of pentagonal faces. A local structure study using EXAFS supports the coexistence of Ge and Ni on the 6c site. Electron diffraction in TEM reveals no detectable Ge/Ni ordering. © 2012 International Centre for Diffraction Data. [doi:10.1017/S0885715612000024] Key words: type I clathrate, Ba8Ni4Ge42, crystal structure, neutron diffraction, TEM, synchrotron EXAFS

I. INTRODUCTION

The recent and rapid renewal of research interest in thermoelectric materials has been driven by several critical factors: the need to increase the efficiency of power generation from waste heat and the efficiency of refrigeration technology, the need to reduce fuel consumption and therefore the dependence on fossil oil, and the need to reduce greenhouse gas emissions. Reports of considerably improved efficiency for a number of new materials, expressed as a figure of merit ZT (ZT = S2T/ρκ, where ρ is the resistivity and κ is the thermal conductivity), have also drawn much attention (Tritt, 1996; Venkatasubramanian et al., 2001; Hsu et al., 2004; Ghamaty and Eisner, 2005; Dresselhaus et al., 2007). Thermoelectric materials with desirable properties (ZT ≫ 1, i.e., characterized by high electrical conductivity, high thermal power, and low thermal conductivity) are required for widespread applications. Among various families of known thermoelectric materials (Nolas et al., 2006), the inorganic clathrates have attracted attention of the thermoelectric community in recent years (Cordier and Woll, 1991; Kuhl et al., 1995; Bobev and Sevov, 1999, 2000; Hermann et al., 1999; Nolas et al., 1999; Chakoumakos et al., 2000; Gryko et al., 2000; Gatti et al., 2003; Kaduk et al., 2003; Paschen et al., 2003; Christensen et al., 2006, 2010; Kishimoto et al., 2007; Deng et al., 2009; Yan et al., 2009). Type I compounds have a general formula of A8E46 and type II compounds have a general formula of A8B16E136. The crystal structures a)

Author to whom correspondence should be addressed. Electronic mail: [email protected] 25

Powder Diffraction 27 (1), March 2012

of these compounds contain two crystallographically distinct voids (i.e., large interstitial sites) that can accommodate rattling guest atoms. In type I compounds the two voids exhibit similar sizes (cage size of 24 vs. 20 atoms), whereas in type II compounds the void sizes differ significantly (cage size of 28 vs. 20 atoms). Rattling guest atoms located in these voids scatter phonons, thereby reducing thermal conductivity. Much research work has focused on type I materials because many of them are semiconductors with favorable thermoelectric properties (Cordier and Woll, 1991; Kuhl et al., 1995; Hermann et al., 1999; Nolas et al., 1999; Chakoumakos et al., 2000; Gatti et al., 2003; Paschen et al., 2003; Christensen et al., 2006, 2010; Kishimoto et al., 2007; Deng et al., 2009; Yan et al., 2009). The majority of type II materials are metals and attempts are being made to convert them into semiconductors by substituting framework, alloying, and modifying cage sizes in the structure (Beekman et al., 2007, 2009; Shi et al., 2010). Despite extensive efforts, the maximum ZT value of type I clathrates remains below 1, with the exception of several single crystals. In a recent article Shi et al. (2010), we demonstrated that transition metal doping introduces charge distortion and lattice defects into these materials, which increase the ionized impurity scattering of carriers and point defect scattering of lattice phonons, respectively. These effects enhance power factors, reduce lattice thermal conductivity, and therefore improve a thermoelectric figure of merit. We briefly depicted the structure of the Ni-doped Ba8Ni4Ge42 phase (Shi et al., 2010). The present paper describes detailed structural characterization of the Ba8Ni4Ge42 phase using neutron diffraction, transmission electron microscopy (TEM), and extended X-ray absorption fine structure

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(EXAFS) measurements. X-ray diffraction patterns are especially important for phase characterization. Therefore, another goal of this investigation was to obtain reliable values of d-spacing and relative intensity of observed hkl reflections of the title compounds from an experimental X-ray diffraction pattern and to make them widely available through submission to the Powder Diffraction File [PDF (ICDD, In press)].

II. EXPERIMENTAL1

The Ba8Ni4Ge42 sample was prepared by induction melting of a mixture of elemental barium (Ba), nickel (Ni), and germanium (Ge) with excess (10%) Ba under an Ar atmosphere. The resulting melts were ground into fine powders, cold pressed into pellets, and annealed at 800 °C for one week. Annealing was done for an additional week to ensure uniform distribution for all elements. The final materials were reground into powders and consolidated by Spark Plasma Sintering at 650 °C for 10 min under a pressure of 50 MPa. Powder X-ray diffraction was used to determine the purity of the sample. Neutron powder diffraction data were collected using the 32-detector BT-1 diffractometer with a Cu (311) monochromator (λ = 1.5403 Å) at the NIST Center for Neutron Research. Samples were loaded in a 0.5-inch-diameter vanadium can. Measurements were done under ambient conditions. The 2θ angular scanning range was 10°–160° in steps of 0.05°. Structure refinement was performed using the program GSAS (Larson and von Dreele, 1992) and the initial structure parameters were taken from the report on Sr8Ga16Ge30 (Kaduk et al., 2003). The neutron scattering lengths for Ba, Ni, and Ge were 0.525, 1.03, and 0.819 × 10−12 cm, respectively. The scale factor, background function parameters (high-order polynominals), profile parameters U, V, and W, asymmetry coefficient, unit-cell parameters, atomic coordinates, and displacement factors Uij were refined. The relatively large contrast in scattering amplitudes between Ni and Ge made it possible to determine the specific Ge site for Ni substitution; therefore, the site occupancies for all Ba and Ge/Ni were refined. In the final cycles, the occupancy factors of atoms that did not show significant deviation from 1.0 were fixed at 1.0. The mean-squared displacement factors of the same atom types were constrained to be equal. Samples for TEM were prepared by dispersing the Ba8Ni4Ge42 powder on lacey carbon-coated grids. Electron diffraction experiments were conducted in a Philips TEM CM-30 operated at 200 kV. EXAFS data were collected at room temperature in transmission for the Ni K-edge using the NIST X23A2 beam-line at the National Synchrotron Light Source. The double-crystal monochromator was operated with a pair of Si (311) crystals. The data were processed using the Athena code (Ravel and Newville, 2005) to extract EXAFS oscillations. Structural parameters were obtained by fitting the EXAFS Fourier transform, calculated using the FEFF6.0 (Ravel and Newville, 1

Certain trade names and company products are mentioned in the text or identified in illustrations in order to adequately specify the experimental procedures and equipment used. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology (NIST). 26

Powder Diffr., Vol. 27, No. 1, March 2012

2005) code, to the experimental data. The fit was accomplished using Artemis software (Zabinsky et al., 1995). The Ba8Ni4Ge42 powder was mounted in a corundum cell to measure the X-ray diffraction reference pattern in vacuum (≈0.013 Pa) on a PANalytical X’Pert Pro MPD diffractometer equipped with a PIXcel position-sensitive detector, a graphite diffracted-beam monochromator, and an Anton Paar HTK 1200N furnace. The pattern was measured (CuKα1 radiation of 1.540 63 Å, 40 kV, 40 mA, and 0.5° divergence slit) from 5 to 148° 2θ in steps of 0.013° for 0.5 s per step. The reference pattern was obtained using the Rietveld pattern decomposition technique (Larson and von Dreele, 1992). In this technique, the peak positions are derived from the integrated intensities and positions calculated from the unit-cell parameters. When peaks are not resolved at the resolution function characteristics of a good laboratory diffractometer, the intensities are summed, and an intensity-weighted d-spacing is reported. Therefore, these patterns represent ideal specimen patterns. They are corrected for systematic errors both in d-spacing and in intensity.

III. RESULTS AND DISCUSSION A. Structure of Ba8Ni4Ge42

The results of Rietveld refinements using neutron powder diffraction for Ba8Ni4Ge42 are presented in Figure 1. The final refinements yielded residuals of Rwp = 0.0497, Rp = 0.0419, and χ2 = 0.91 (with 37 variables and 2999 reflections). The refined atomic coordinates and atomic displacement parameters (ADPs) are reported in Tables I and II, respectively. The bond distances are listed in Table III. Ba8Ni4Ge42 crystallizes with the cubic structure [Pm3n, a = 10.6769(2) Å and V = 1217.13(6) Å3]. Our results, in general, agree with the single-crystal work by Nguyen et al. (2010). Figures 2(a) and 2(b) highlight two different types of polyhedra that form a unit cell of Ba8Ni4Ge42. The dodecahedron (20-atom cage with 12 pentagonal faces, Ge20) and the tetrakaidecahedron (24-atom cage with 12 pentagonal and 2 hexagonal faces, Ge24) are depicted in Figure 3. Each unit cell contains two Ge20 dodecahedra and six Ge24 tetrakaidecahedra. The Ge20 dodecahedra are linked via the interstitial 6c positions. The framework structure is formed by the tetrahedrally bounded network of Ge. Ba atoms reside in both the Ge20 and Ge24 cavities at the 2a and 6d sites, respectively. Ni atoms were found to exclusively occupy the 6c (¼ 0 ½) sites (Ge3) with the Ni:Ge ratio of 1:1 (Table I); these sites are located on the hexagonal faces of the larger tetrakaidecahedra (Figure 3). No Ni atoms were found in the smaller dodecahedra that consist of pentagonal faces. The stoichiometry of the compound was refined to Ba8Ni3.2(3)Ge42.8. Although the formula appears to be Ba8Ni4Ge42 within 3σ standard deviation of Ni concentration on the 6c site, there is possible Ni vacancy as suggested in the single-crystal work by Nguyen et al. (2010). The preferential 6c site occupancy for Ni in Ba8Ni4Ge42 agrees well with previous reports on M-substituted compounds such as Ba8Cd8Ge38 (Czybulka et al., 1991), Cs8Cd4Sn42 (Wilkinson et al., 2002), Ba8Mn2Ge44 (Kawaguchi et al., 2000), and Cs8Zn4Sn42 (Nolas et al., 2006). Thus, the 6c site selection does not seem to be size dependent on the substituents. According to Gimarc (1983), the substitution site preference can be Wong-Ng et al.

26

Figure 1. (Color online) Observed (crosses) and calculated (solid line) XRD pattern for Ba8Ni4Ge42 by the Rietveld analysis technique. The difference pattern is plotted at the same scale as the other patterns. The row of tick marks indicates the calculated peak positions.

TABLE I. Refined coordinates for type I Ba8Ni4Ge42 (X-ray data are shown on the second line). Atom

Wyckoff position

x

y

z

Site occupancy

Ba1 Ba2 Ni/Ge3 Ge4

2a 6d 6c 16i

Ge5

24k

0 1/4 1/4 0.183 61(6) 0

0 1/2 0 0.183 61(6) 0.3165(1)

0 0 1/2 0.183 61(6) 0.1217(1)

1.0 1.0 0.53(5) 0.99(1) 1.00(1)

TABLE II. Refined displacement parameters (Uij × 100, Å2) for type I Ba8Ni4Ge42. Atom Ba1 Ba2 Ni/Ge3 Ge4 Ge5

U11

U22

U33

U12

U13

U23

1.43(12) 2.3(2) 1.54(9) 1.12(3) 1.00(5)

4.7(2) 1.08(7) 1.12(3) 1.66(6)

4.7(2) 1.08(7) 1.12(3) 2.17(6)

−0.14(3) 0

−0.14(3) 0

−0.14(3) 0.58(5)

Figure 2. (Color online) Framework structure of type I Ba8Ni4Ge42 clathrate featuring face-sharing Ge20 dodecahedra and Ge24 tetrakaidecahedra.

TABLE III. Bond distances (Å) in Ba8Ni4Ge42. Bond

Distance

Ba1–Ge4 Ba1–Ge5 Ba2–Ni/Ge3 Ba2–Ge4 Ba2–Ge5 Ge3/Ni–Ge5 Ge4–Ge5 Ge4–Ge4 Ge5–Ge5 Ge5–Ge4 Ge5–Ge3/Ni

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3.3956(12) × 8 3.6208(10) × 12 3.774 86(4) × 2 3.774 86(6) × 2 3.9695(4) × 8 3.5576(6) × 8 4.0996(10) × 4 2.3899(11) × 4 2.5081(7) × 3 2.455(2) 2.602(2) 2.5081(7) × 2 2.3899(11)

Figure 3. (Color online) Three crystallographically distinct framework sites in the structure are shown. The 6c, 16i, and 24k positions are shown as green, red, and black, respectively. Crystal structure of type I clathrate Ba8Ni4Ge42

27

Figure 4. Representative selected area electron diffraction patterns recorded from the same single-crystalline grain of Ba8Ni4Ge42. In these patterns, “z.a.” stands for zone axis.

explained using the rule of topological charge stabilization and Mulliken population analysis (Miller, 1996). The analysis suggests that the electropositive (or less electronegative) species occupy the framework sites with the lowest Mulliken population, whereas more electronegative species prefer the sites with the highest Mulliken population. On the basis of the findings of Miller (1996) that, in type I clathrate K8Si44, the 6c site has the lowest Mulliken population, Wilkinson et al. (2002) suggested that, in Cs8Cd4Sn42, the framework 6c Sn sites are expected to be substituted by less electronegative Cd atoms. Following these arguments, in Ba8Ni4Ge42, Ni, which is less electronegative (χNi = 1.91) than Ge (χGe = 2.01) (Pauling, 1960), is expected to substitute Ge on the 6c sites, as confirmed by our experimental results. Different atomic sizes of Ge (covalent radius of 1.22 Å) and Ni (1.10 Å) (Pyykkö and Atsumi, 2009) affect bond lengths in Ba8Ni4Ge42. Table III lists all Ba1–Ge distances in the smaller Ge20 cage [ranging from 3.3956(12) to 3.6208 (10) Å] and Ba2–Ge distances [ranging from 3.5576(6) to 4.0996(10) Å] in the larger Ge24 cage. The Ge–Ge distances in Ba8Ni4Ge42 were found to be in the range 2.455(2)–2.602 (2) Å. These Ge–Ge distances are somewhat longer than those in pure Ge (2.445 Å) (Kaduk et al., 2003). The elongation can be attributed to the “extra” electrons available from Ba. The average bond length Ge–(Ge/Ni) [2.3899(11) Å] is significantly shorter because the atomic size of Ni is smaller than that of Ge. The tetrahedral angles around Ge sites are: Ge3/Ni [109.14(2)°–110.14(5)°], Ge4 [106.60(4)°–112.66 (3)°], and Ge5 [102.83(5)°–108.25(4)°]. Of these three tetrahedral sites, the Ge3/Ni site is the least distorted, relative to the ideal angle of 109.45°. Table II summarizes the ADPs for Ba8Ni4Ge42. The ADP anisotropy may have an effect on the transport properties. Similar to the Cs atoms in Cs8Zn4Sn42 (Nolas et al., 1999), Ba atoms in the larger Ge24 cavities of Ba8Ni4Ge42 also exhibit greater (or more anisotropic) thermal motion than those in the smaller Ge20 cavities. As seen in the second column of 28

Powder Diffr., Vol. 27, No. 1, March 2012

Figure 5. (Color online) (a) The k2-weighted EXAFS data for the Ni K-edge. (b) Magnitude of EXAFS Fourier transform (FT). The k-range used in the FT was 3.1–14.6 Å−1. Before an FT, the EXAFS signal was multiplied by the Hanning window with dk = 1. The r-space fitting range was 1–4 Å. Dotted and solid lines represent experimental and calculated data, respectively. Wong-Ng et al.

28

Table II, Ba1 atoms located in smaller cages exhibit nearly isotropic ADPs (U11 of 1.43 Å2), which acquire values similar to those of the framework atoms Ge and Ge/Ni. In contrast, the ADP U22 and U33 displacement factors of Ba2 (4.7 and 4.7, respectively) are three to four times larger than those for Ge, Ge/Ni, and Ba1. These large ADP values likely reflect rattling motions of Ba2 inside the large cage, which are expected to contribute to phonon scattering essential for reducing thermal conductivity. Neutron refinements provided no evidence of Ba2 disorder among off-centered sites in the tetrakaidecahedral cage.

B. TEM study

Representative selected area electron diffraction patterns recorded from the same crystallite of Ba8Ni4Ge42 are shown in Figure 4. The observed reflection conditions hhl: l = 2n and h00: h = 2n match the Pm3n symmetry. Some of the weak diffraction spots seen in the patterns are associated with adjacent crystallites encompassed by the selected area diffraction aperture, whereas others arise from a contribution of reflections from the first-order Laue zone. The diffraction patterns revealed no visible superlattice reflections or diffuse scattering, thus ruling out any significant Ge/Ni ordering.

C. Local structure study

The normalized k-weighted EXAFS signal and its Fourier transform are shown in Figure 5(a) (dotted line). A starting cluster for the local-structure refinements was generated on the basis of the average structure obtained from neutron diffraction. The first two coordination shells, Ni–Ge and Ni– Ba, were included in the fit. The refined parameters included the energy shift, Ni–Ge and Ni–Ba distances, and their associated Debye–Waller (σ) factors. The results of the fit are displayed in Figure 5(b) (solid line). The refinements yielded RNiGe = 2.314(5) Å, σNiGe = 0.006(1) Å2, RNiBa = 3.73(2) Å, and σNiBa = 0.012(2) Å2. In a typical Ba8Ni4Ge42 structure, the Ge4 site is four-fold coordinated exclusively by Ge atoms (1Ge4 + 3Ge5). The average Ge–Ge distance for this coordination cluster estimated from Rietveld refinements is ≈2.50 Å. Therefore, for a mixed Ge0.33Ni0.67 site, the average distance to the neighboring Ge atoms is expected to be equal to ≈(1/3RGeGe + 2/3RNiGe) = (1/3 × 2.50 Å + 2/3 × 2.31 Å) ≈ 2.373 Å; here, the RNiGe distance was adopted from the EXAFS measurements. This estimate agrees well with R = 2.390 Å obtained for the distance between the mixed Ge3/Ni and pure Ge4 positions from Rietveld refinements. Thus, our EXAFS measurements support a 1:2 mixture of Ge and Ni on the 6c sites within the Pm3n structure suggested by Rietveld refinements. The next

 TABLE IV. X-ray powder pattern for Ba8Ni4Ge42 [Pm3n,a = 10.6744(1) Å, V = 1216.28(1) Å3, and Dx = 5.986 g cm−3; λ (CuK α1) = 1.540 63 Å]. d 7.5480 3.3755 2.8529 2.5160 2.1789 1.9822 1.8307 1.7791 1.7316 1.6671 1.5739 1.4526 1.3557 1.2945 1.2580 1.2409 1.2165 1.1788 1.1510 1.1315 1.1190 1.0783 1.0569 1.0178 0.9911 0.9510 0.9398 0.9326 0.9153 0.8895 0.8492 0.8387 0.8335

i

h

k

l

9 5 999* 60 11 38 277 205 373 29 25 45 64 21 25 33 16 6 55 25 5 40 6 15 14 25 5 8 6 15 28 24 37

1 3 3 3 4 4 4 4 5 6 6 6 7 8 6 7 8 8 6 8 9 8 10 9 8 9 8 11 10 8 10 9 8

1 1 2 3 2 3 3 4 3 2 3 3 3 2 6 5 3 3 5 4 3 5 1 5 6 6 7 3 6 8 7 9 8

0 0 1 0 2 2M 3M 2M 2M 1M 1 3+ 2M 0 0M 0M 2M 3 5+ 3M 1 3 1 2M 4 3M 4 1 0 4M 3M 0M 6M

d

i

h

k

l

4.7737 3.0814 2.6686 2.3869 2.1349 1.9489 1.8307 1.7791 1.7316 1.6671 1.5407 1.4016 1.3139 1.2758 1.2494 1.2244 1.2086 1.1717 1.1379 1.1252 1.1010 1.0674 1.0467 1.0178 0.9827 0.9510 0.9362 0.9291 0.9022 0.8865 0.8492 0.8387 0.8285

5 221 90 33 37 13 277 205 373 29 26 8 41 12 16 25 11 13 5 41 19 11 13 15 9 25 22 9 12 5 28 24 31

2 2 4 4 4 5 5 6 6 5 4 7 8 6 8 6 7 7 6 9 7 10 8 10 9 10 9 8 10 12 11 11 9

1 2 0 2 3 2 3 0 1 4 4 3 1 5 3 6 5 5 6 3 6 0 6 3 6 5 7 8 6 1 6 5 7

0 2 0 0 0 1 0M 0M 1M 0M 4 0 1M 3 0 2 2 3 4 0M 3 0 2 1M 1 1M 0M 2 2 0 1M 4M 6M

d

i

h

k

l

4.3578 2.9606 2.5889 2.2758 1.9822 1.8870 1.8043 1.7549 1.6878 1.5913 1.4662 1.3557 1.3139 1.2580 1.2409 1.2165 1.1934 1.1647 1.1315 1.1252 1.0895 1.0621 1.0368 0.9954 0.9548 0.9435 0.9362 0.9221 0.8895 0.8716 0.8413 0.8335 0.8285

9 419 141 7 38 30 99 5 32 13 36 64 41 25 33 16 27 20 25 41 38 6 9 10 7 11 22 46 15 20 13 37 31

2 3 4 3 5 4 5 6 6 5 6 6 5 8 8 6 8 8 8 8 8 7 9 9 8 8 11 11 12 10 9 12 11

1 2 1 3 2 4 3 1 2 4 4 5 5 2 3 5 4 4 5 5 4 6 5 5 6 8 3 3 0 5 8 4 6

1 0 0 2 0M 0 1 0 0 2 1 1M 4M 2M 1M 4M 0 2 0M 1M 4 4 0 3 5 0 0M 2+ 0M 5+ 4 2M 3M

The pattern was measured in vacuum ( ≈ 0.013 Pa). The symbols “M” and “ + ” refer to peaks containing contributions from two and more than two reflections, respectively. The symbol * indicates that the particular peak has the strongest intensity of the entire pattern and is assigned a value of 999. 29

Powder Diffr., Vol. 27, No. 1, March 2012

Crystal structure of type I clathrate Ba8Ni4Ge42

29

nearest-neighbor coordination for the mixed Ge3/Ni site includes 4 Ba1 atoms. The EXAFS Debye–Waller factor for the Ni–Ba shell (0.012 Å2) is similar to the ADP value obtained for the Ba1 site (0.014 Å2) from neutron diffraction. D. Powder X-ray diffraction pattern

The powder X-ray diffraction pattern for Ba8Ni4Ge42 (Table IV) was submitted to the International Centre for Diffraction Data (ICDD) to be included in the PDF. The atomic coordinates obtained from Rietveld refinements agree well with the results from neutron diffraction. The cell parameter data obtained from X-ray diffraction [a = 10.6744(1) Å and V = 1216.28(1) Å3] were smaller than data obtained from neutron diffraction [a = 10.6769(2) Å and V = 1217.13 (6) Å3] as the X-ray pattern was collected under vacuum (≈0.013 Pa). The intensity values reported are integrated intensities rather than peak heights. IV. SUMMARY

Type I clathrate, Ba8Ni4Ge42, contains Ni exclusively on the least-distorted framework Ge 6c sites. EXAFS measurements supported a 1:2 mixture of Ge and Ni on the 6c (¼ 0 ½) sites within the Pm3n structure. Electron diffraction patterns revealed no visible signs of Ge/Ni ordering. Powder diffraction patterns for Ba8Ni4Ge42 have been submitted to be published in the PDF. ACKNOWLEDGMENTS

Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This work utilized facilities supported in part by the National Science Foundation under Agreement No. DMR-0454672. Drs. X. Shi and Y. Yang acknowledge the partial support from the U.S. Department of Energy. Dr. G. Liu is thanked for his graphical assistance. Beekman, M., Wong-Ng, W., Kaduk, J.A., Shapiro, A., and Nolas, G. S. (2007). “Synthesis and single-crystal X-ray diffraction studies of new framework substituted type II clathrates, Cs8Na16AgxGe136−x (x < 7),” J. Solid State Chem. 180, 1076–1082. Beekman, M., Kaduk, J. A., Gryko, J., Wong-Ng, W., Shapiro, A., and Nolas, G. S. (2009). “Synthesis and transport properties of framework-substituted Cs8Na16Cu5Ge131,” J. Alloys Compd. 470, 365–368. Bobev, S. and Sevov, S. C. (1999). “Synthesis and characterization of stable stoichiometric clathrates of silicon and germanium: Cs8Na16Si136 and Cs8Na16Ge136,” J. Am. Chem. Soc. 121, 3795–3796. Bobev, S. and Sevov, S. C. (2000). “Clathrates of group 14 with alkali metals: an exploration,” J. Solid State Chem. 153, 92–105. Chakoumakos, B. C., Sales, B. C., Mandrus, D. G., and Nolas, G. S. (2000). “Structural disorder and thermal conductivity of the semiconducting clathrate Sr8Ga16Ge30,” J. Alloys Compd. 296, 80–86. Christensen, M., Juuranyi, F., and Iversen, B. B. (2006). “The rattler effect in thermoelectric clathrates studied by inelastic neutron scattering,” Physica B 385, 505–507. Christensen, M., Johnson, S., and Iversen, B. B. (2010). “Thermoelectric clathrates of type I,” Dalton Trans 39, 978–992. Cordier, G. and Woll, P. (1991). “Neue ternae intermetallische Verbinddungen mit Clathratstruktur Ba8(T,Si)6Si40 and Ba6(T,Ge)6Ge40 mit T = Ni, Pd, Pt, Cu, Ag, Au,” J. Less Common Metals 169, 291–302.

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Czybulka, A., Kuhl, B., and Schuster, H.-U. (1991). “Neue ternäre, Käfigverbindungen in den Systemen Barium-2B(3B)-ElementGermanium,” Z. Anorg. Allg. Chem. 594, 23–28. Deng, S.-K., Tang, X. F., and Tang, R. S. (2009). “Synthesis and high temperature thermoelectric transport properties of S-based type-I clathrates,” Chin. Phys. Soc. 18(07), 3084–3089. Dresselhaus, M. S., Chen, G., Tang, M. Y., Yang, R. G., Lee, H., Wang, D. Z., Ren, Z. F., Fleurial, J. P., and Gogna, P. (2007). “New directions for low-dimensional thermoelectric materials,” Adv. Mater. 19, 1043–1053. Gatti, C., Bertini, L., Blake, N. P., and Iversen, B. B. (2003). “Guest-framework interaction in type I inorganic clathrates with promising thermoelectric properties: on the ionic versus neutral nature of the alkaline-earth metal guest A in A8Ga16Ge30 (A = Sr, Ba),” Chem. Eur. J. 9(18), 4556–4568. Ghamaty, S. and Eisner, N. B. (2005). “Quantum well thermoelectric devices,” Proceeding of Interpack 2005: ASME Technical Conference on Packaging of MEMS, NEWS and Electric Systems, July 17–22, San Francisco, CA. Gimarc, B. M. (1983). “Topological charge stabilization,” J. Am. Chem. Soc. 105, 1979–1984. Gryko, J., Marzke, R. F., Ramachandran, G. K., Patton, D., Deb, S. K., and Sankey, O. F. (2000). “Low-density framework form of crystalline silicon with a wide optical band gap,” Phys. Rev. B62, R7707–R7710. Hermann, R. F. W., Tanigaki, K., Kawaguchi, T., Kuroshima, S., and Zhou, O. (1999). “Electronic structure of Si and Ge gold-doped clathrates,” Phys. Rev. B60(19), 13245–13428. Hsu, K. F., Loo, S., Guo, F., Chen, W., Dyck, J. S., Uher, C., Hogan, T., Polychroniadis, E. K., and Kanatzidis, M. G. (2004). “Cubic AgPbmSbTe2+m: bulk thermoelectric materials with high figure of merit,” Science 303, 818–821. ICDD (2012). Powder Diffraction File (International Centre for Diffraction Data, Newtown Square, PA, USA (In press). Kaduk, J. A., Wong-Ng, W., and Nolas, G. S. (2003). “X-ray diffraction patterns of two semiconducting clathrates, Sr8Ga16Ge30 and Cs8Na16Ge136: promising candidates for thermoelectric applications,” Rigaku J. 20(2), 2–11. Kawaguchi, T., Tanigaki, K., and Yasukawa, M. (2000). “Ferromagnetisn in germanium clathrate: Ba6Mn2Ge44,” Appl. Phys. Lett. 77(21), 3438–3440. Kishimoto, K., Koyanagi, T., Akai, K., and Matsuura, M. (2007). “Synthesis and thermoelectric properties of type-I clathrate compounds Si46−xPxTe8,” Jpn. J. Appl. Phys. 46, L746–L748. Kuhl, B., Czybulka, A., and Schuster, H.-U. (1995). “New ternary clathrate compounds in the systems barium–indium/zinc/cadmium–germanium: zintl compounds with phase width?,” Z. Anorg. Allg. Chem. 621, 1–6. Larson, A. C. and von Dreele, R. B. (1992). GSAS—General Structure Analysis System, U.S. Government Contract (W-7405-ENG-36) by the Los Alamos National Laboratory, University of California, for the U.S. Department of Energy. Miller, G. J. (1996) in “Structure and bonding at the zintl border,” Chemistry, Structure, and Bonding of Zintl Phases and Ions, edited by S. M. Kauzlarich (VCH, New York), pp. 1–59. Nguyen, L. T. K., Aydemir, U., Baitinger, M., Bauer, E., Borrmann, H., Burkhardt, U., Custers, J., Haghighirad, A., Höfler, R., Luther, K. D., Ritter, F., Assmus, W., Grin, Yu., and Paschen, S. (2010). “Atomic ordering and thermoelectric properties of the n-type clathrate Ba8Ni3.5Ge42.10.4,” Dalton Trans. 39, 1071–1077. Nolas, G. S., Weakley, T. J. R., and Cohn, J. L. (1999). “Structural, chemical, and transport properties of a new clathrate compound: Cs8Zn4Sn42,” Chem. Mater. II, 2470–2473. Nolas, G. S., Poon, J., and Kanatzidis, M. (2006). “Recent developments in bulk and thermoelectric materials,” MRS Bull. 31, 199–205. Paschen, S., Pacheco, V., Bentien, A., Sanchez, A., Carrillo-Cabrera, W., Baenitz, M., Iversen, B.B., Grin, Yu., and Steglich, F. (2003). “Are type-I clathrates zintl phases and phonon glasses and electron single crystals,” Physica B 328, 39–43. Pauling, L. (1960). The Nature of the Chemical Bond (Cornell University Press, Ithaca, New York), 3rd ed. Pyykkö, P. and Atsumi, M. (2009). “Molecular single-bond covalent radii for elements 1–118,” Chem. Eur. J. 15, 186–197. Ravel, B. and Newville, M. (2005). “ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT,” J. Synchrotron Radiat. 12, 537. Shi, X., Yang, J., Bai, S., Yang, J., Wang, H., Salvador, J. R., Zhang, W., Chen, L., and Wong-Ng, W. (2010). “On the design of high efficiency thermoelectric type I clathrates through transition metal doping,” Adv. Funct. Mater. 20, 755–763. Tritt, T. M. (1996). “Thermoelectrics run hot and cold,” Science 272, 1276–1277.

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Venkatasubramanian, R., Siivola, E., Colpitts, T., and O’Quinn, B. (2001). “Thin-film thermoelectric devices with high room-temperature figures of merit,” Nature 413, 597–602. Wilkinson, A. P., Lind, C., Young, R. A., Shastri, S. D., Lee, P. L., and Nolas, G. S. (2002). “Preparation, transport properties and structure analysis by resonant X-ray scattering of the type-I clathrate Cs8Cd4Sn42,” Chem. Mater. 14, 1300–1305.

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Yan, Y., Tang, X., Li, P., and Zhang, Q. (2009). “Microstructure and thermoelectric transport properties of type I clathrates Ba8Sb2Ga14Ge30 prepared by ultra rapid solidification process,” J. Electronic Mater. 38 (7), 1278. Zabinsky, S. I., Rehr, J. J., Ankudinov, A., Albers, R. C., and Eller, M. J. (1995). “Multiple scattering calculations of X-ray absorption spectra,” Phys. Rev. B. 52, 2995–3009.

Crystal structure of type I clathrate Ba8Ni4Ge42

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Chemical preparation and XRD data for four cyclotriphosphates: Ba3(P3O9)2·4H2O, BaNH4P3O9·2H2O, BaTlP3O9·2H2O, and BaTlP3O9·Ba3(P3O9)2·4H2O A. Kheïreddine,a) M. Tridane, and S. Belaaouada) Laboratoire de Recherches de Chimie—Physique Générale des Matériaux, Faculté des Sciences Ben M’sik, B. P. 7955. Bd Cdt Driss El Harti, Université Hassan II- Mohammedia, Casablanca, Morocco

(Received 15 December 2011; accepted 03 January 2012) Methods of chemical preparation and XRD data are reported for four cyclotriphosphates associated with barium alone and with ammonium and thallium. These phosphates are Ba3(P3O9)2·4H2O, BaNH4P3O9·2H2O, BaTlP3O9·2H2O, and BaTlP3O9·Ba3(P3O9)2·4H2O was prepared by the direct method of chlorures, BaNH4P3O9·2H2O and BaTlP3O9·2H2O by the method of ion-exchange resin, and BaTlP3O9 by total dehydration of BaTlP3O9·2H2O. Ba3(P3O9)2·4H2O is monoclinic, space group P21/n, Z = 4, with a = 7.546(3), b = 12.105(4), c = 11.649(4) Å, β = 100.340(3)°, V = 1046.8(2) Å3, M(20) = 81, and F(20) = 117(0.003 419, 50). BaNH4P3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.547(1), b = 12.065(1), c = 11.697(1) Å, β = 101.111(1)°, V = 1045.1(3) Å3, M(20) = 9 (AV.EPS = 0.000 116 9), and F(20) = 14(0.0287 06, 53). BaTlP3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.546(3), b = 12.105(4), c = 11.649(4) Å, β = 100.340(3)°, V = 1046.8(2) Å3, M(20) = 81, and F(20) = 117(0.003 419, 50). BaNH4P3O9·2H2O and BaTlP3O9· 2H2O are isostructural. BaTlP3O9 is orthorhombic, space group P212121, Z = 4, with a = 11.086(2), b = 12.283(2), c = 5.786(1) Å, V = 787.9(4) Å3, M(20) = 10 (AV.EPS = 0.000 116 9), and F(20) = 14 (0.026 955, 56). © 2012 International Centre for Diffraction Data. [doi:10.1017/S0885715612000061] Key words: Ba3(P3O9)2·4H2O, BaNH4P3O9·2H2O, BaTlP3O9·2H2O, BaTlP3O9, X-ray powder diffraction

I. INTRODUCTION

Thermal behavior studies of cyclotriphosphates associated with barium alone and with ammonium and thallium, Ba3(P3O9)2·nH2O (n = 6 and 4) (Averbuch-Pouchot and Durif, 1986; Belaaouad et al., 2009) and BaMIP3O9·2H2O (MI = NH4 and Tl) (Belaaouad et al., 2000; Belaaouad, 2002) reported a new form of cyclotriphosphate BaTlP3O9. This study reports the chemical preparation and the XRD data for four cyclotriphosphates associated with barium alone and with ammonium and thallium, Ba3(P3O9)2·4H2O (AverbuchPouchot and Durif, 1986), BaNH4P3O9·2H2O (Belaaouad et al., 2000; Belaaouad et al., 2001; Belaaouad, 2002), BaTlP3O9·2H2O (Sbai and Belaaouad, 2003), and BaTlP3O9 (Sbai and Belaaouad, 2003). The thermal behavior of Ba3(P3O9)2·nH2O (n = 6 and 4) (Averbuch-Pouchot and Durif, 1986; Belaaouad et al., 2009) was studied in our laboratory. BaNH4P3O9·2H2O and BaTlP3O9·2H2O are isostructural. The crystal structure of BaTlP3O9 has not been previously reported in the literature. The four condensed phosphates are stable in normal conditions of temperature and hygrometry.

A. Synthesis 1. Ba3 (P3O9)2·4H2O

Chemical preparation of pure Ba3(P3O9)2·4H2O is difficult to optimize. Large crystals of cyclotriphosphate Authors to whom correspondence should be addressed. Electronic mails: [email protected] and [email protected] 32

Powder Diffraction 27 (1), March 2012

3BaCl2 · 2H2 O + 2Na3 P3 O9  Ba3 (P3 O9 )2 · 4H2 O + 6NaCl + 2H2 O. Ba3(P3O9)2·4H2O is stable until its melting point at 870 °C. 2. BaNH4P3O9·2H2O

Single crystals of BaNH4P3O9·2H2O were prepared by slowly adding dilute cyclotriphosphoric acid, H3P3O9, to an aqueous solution of barium carbonate, BaCO3, and ammonium carbonate, (NH4)2CO3, with a stoichiometric ratio Ba/NH4 = 1, according to the following chemical reaction: H3 P3 O9 + BaCO3 + 1/2(NH4 )2 CO3 + 1/2H2 O BaNH4 P3 O9 · 2H2 O + 3/2CO2 .

II. EXPERIMENTAL

a)

tetrahydrate of barium, Ba3(P3O9)2·4H2O, were prepared by mixing 30 g of BaCl2·2H2O and 6 g of Na3P3O9 (Ba/Na = 2) in 50 ml of water without stirring for 5 h, as shown in the following chemical reaction:

The solution was then slowly evaporated at room temperature until large rectangular prisms of BaNH4P3O9·2H2O were obtained. The cyclotriphosphoric acid, H3P3O9, used in this reaction was prepared from an aqueous solution of Na3P3O9 passed through an ion-exchange resin “Amberlite IR 120” (Jouini and Durif, 1983). Na3P3O9 was obtained by thermal treatment of sodium dihydrogenomonophosphate, at 530 °C for 5 h in air, according to the following chemical

0885-7156/2012/27(1)/32/4/$18.00

© 2012 JCPDS-ICDD

32

reaction: 3NaH2 PO4  Na3 P3 O9 + 3H2 O. The weight loss, as a result of slowly heating up to a temperature of 200 °C, confirmed the compound to be dihydrate. BaNH4P3O9·2H2O is stable in air for many months under normal conditions of temperature and humidity. 3. BaTlP3O9·2H2O

Single crystals of BaTlP3O9·2H2O were prepared by slowly adding dilute cyclotriphosphoric acid, H3P3O9, to an aqueous solution of barium carbonate, BaCO3, and thallium carbonate, Tl2CO3, with a stoichiometric ratio Ba/Tl = 1, according to the following chemical reaction: H3 P3 O9 + BaCO3 + 1/2Tl2 CO3 + 1/2H2 O BaTlP3 O9 · 2H2 O + 3/2CO2 . The solution was then slowly evaporated at room temperature until single crystals of BaTlP3O9·2H2O were obtained. The cyclotriphosphoric acid, H3P3O9, used in this reaction was prepared by the same process as described for the preparation of BaNH4P3O9·2H2O. The weight loss, as a result of slowly heating up to a temperature of 250 °C, confirmed the compound to be dihydrate. BaTlP3O9·2H2O is stable in air for many months under normal conditions of temperature and humidity. Figure 1. X-ray powder diffraction patterns for four cyclotriphosphates: (a) Ba3(P3O9)2·4H2O, (b) BaNH4P3O9·2H2O, (c) BaTlP3O9·2H2O, and (d) BaTlP3O9.

4. BaTlP3O9

Polycrystalline samples of BaTlP3O9 were prepared by total dehydration of BaTlP3O9·2H2O under atmospheric pressure between 300 and 500 °C according to the following chemical reaction: BaTlP3 O9 · 2H2 O  BaTlP3 O9 + 2H2 O. BaTlP3O9 was found to be stable with further increase in temperature and melted at 560 °C.

was 10–70° with a step size of 0.01° and a counting time of 30 s per step. The program of graphic tool for powder diffraction named WinPLOTR (Version 2010) was used to determine the observed diffraction peak positions for the four compounds. The unit-cell parameters and the figures of merit, M and F, were calculated using the computer program TREOR (Louër and Louër, 1972; Louër and Vargas, 1982).

B. Data collection and reduction

Powder diffraction patterns for the four compounds were collected with a SIEMENS D 5000 diffractometer using Cu Kα1 radiation (λ = 1.5406 Å). The experimental 2θ range

III. RESULTS

Ba3(P3O9)2·4H2O is monoclinic, space group C2/m, Z = 2, with a = 16.090(1), b = 8.368(5), c = 7.717(3) Å,

Table I. Powder diffraction data of Ba3(P3O9)2·4H2O. 2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

20.74 22.15 23.12 23.71 24.78 25.77 27.07 29.33 29.74 30.60

4.28 4.01 3.844 3.750 3.590 3.454 3.291 3.043 3.002 2.919

3 6 7 22 31 8 6 11 7 18

020 400 00–2 311 20–2 11–2 221 31–2 510 40–2

4.18 4.01 3.842 3.756 3.598 3.472 3.283 3.043 2.992 2.912

21.22 22.18 23.13 23.66 24.72 25.70 27.13 29.23 29.83 30.68

0.48 0.03 0.01 −0.05 −0.06 −0.07 0.06 −0.10 0.09 0.08

32.45 36.16 37.44 38.54 43.49 45.35 46.51 61.21 62.45 65.39

2.757 2.482 2.400 2.334 2.079 1.998 1.951 1.513 1.485 1.426

7 7 100 7 11 6 10 8 18 3

130 330 42–2 331 711 531 00–4 803 334 64–3

2.746 2.471 2.39 2.323 2.072 1.997 1.947 1.510 1.486 1.423

32.55 36.30 37.60 38.70 43.64 45.46 46.63 61.33 62.45 65.54

0.10 0.14 0.16 0.16 0.15 0.11 0.12 0.12 0.00 0.15

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Chemical preparation and XRD data for four cyclotriphosphates

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Table II. Powder diffraction data of BaNH4P3O9·2H2O. 2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

10.69 13.01 16.59 17.37 19.49 23.59 24.81 27.24 28.15 28.63 29.22 30.19 30.56 31.12 32.63 32.89 37.83

8.27 6.80 5.34 5.10 4.55 3.769 3.586 3.271 3.167 3.115 3.054 2.958 2.923 2.872 2.742 2.721 2.376

16 11 10 10 38 26 16 39 21 10 100 80 17 36 22 12 19

011 10–1 02–1 012 12–1 031 210 21–2 103 13–2 113 22–2 221 21–3 23–1 13–3 04–3

8.31 6.85 5.34 5.18 4.53 3.795 3.540 3.296 3.160 3.141 3.057 2.979 2.923 2.875 2.74 2.723 2.370

10.63 12.90 16.58 17.10 19.58 23.42 24.90 27.03 28.22 28.39 29.19 30.17 30.62 31.07 32.67 32.85 37.70

−0.06 −0.11 −0.01 −0.27 0.09 −0.17 0.09 -0.21 0.07 −0.24 −0.03 −0.02 0.06 −0.05 0.04 −0.04 −0.13

38.15 40.02 40.47 42.19 42.53 43.04 43.69 44.86 44.90 46.11 47.78 48.49 49.07 49.79 54.34 58.56

2.357 2.251 2.227 2.140 2.124 2.100 2.070 2.019 2.017 1.967 1.902 1.876 1.855 1.830 1.687 1.575

13 23 12 13 31 25 32 13 14 14 16 15 16 40 11 13

05–1 015 05–2 32–3 33–1 330 14–4 22–5 331 32–4 34–2 332 400 410 430 35–4

2.361 2.255 2.224 2.140 2.132 2.103 2.078 2.020 2.012 1.966 1.900 1.878 1.851 1.830 1.682 1.575

38.30 39.95 40.47 42.27 42.53 42.97 43.51 44.81 45.03 46.13 47.85 48.43 49.17 49.79 54.52 58.54

0.15 −0.07 0.00 0.08 0.00 −0.07 −0.18 −0.05 0.13 0.02 0.07 −0.06 0.10 0.00 0.18 −0.02

β = 95.380(5)°, V = 1034.6(3) Å3, M(20) = 10, and F(20) = 6(0.009 337, 280). The powder diffraction pattern of Ba3(P3O9)2·4H2O is plotted in Figure 1(a), and the powder diffraction data for the compound are reported in Table I. BaNH4P3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.547(1), b = 12.065(1), c = 11.697(1) Å, β = 101.111 (1)°, V = 1045.1(3) Å3, M(20) = 9 (AV.EPS = 0.000 116 9), and F(20) = 14(0.028 706, 53). The powder diffraction pattern of BaNH4P3O9·2H2O is plotted in Figure 1(b), and the powder diffraction data for the compound are reported in Table II.

BaTlP3O9·2H2O is monoclinic, space group P21/n, Z = 4, with a = 7.546(3), b = 12.105(4), c = 11.649(4) Å, β = 100.340 (3)°, V = 1046.8(2) Å3, M(20) = 81, and F(20) = 117(0.003 419, 50). BaNH4P3O9·2H2O and BaTlP3O9·2H2O are isostructural. The powder diffraction pattern of BaTlP3O9· 2H2O is plotted in Figure 1(c), and the powder diffraction data for the compound are reported in Table III. BaTlP3O9 is orthorhombic, space group P212121, Z = 4, with a = 11.086(2), b = 12.283(2), c = 5.786(1) Å, V = 787.9 (4) Å3, M(20) = 10(AV.EPS = 0.000 116 9), and F (20) = 14 (0.026 955, 56). The powder diffraction pattern of BaTlP3O9

Table III. Powder diffraction data of BaTlP3O9·2H2O. 2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

10.60 14.02 14.70 15.32 16.49 17.10 18.87 19.24 19.41 21.34 22.49 23.29 23.40 23.97 24.43 25.31 25.88 26.17 26.91 27.00 27.23 28.05 28.44 29.52 30.08 30.76

8.34 6.31 6.02 5.78 5.37 5.18 4.70 4.61 4.57 4.16 3.951 3.816 3.799 3.710 3.640 3.516 3.440 3.402 3.310 3.300 3.272 3.179 3.136 3.024 2.968 2.904

14 10 7 40 82 26 13 46 8 36 13 13 22 100 7 16 13 7 10 7 23 9 10 20 30 15

011 110 020 101 021 012 120 11–2 12–1 02–2 112 00–3 031 200 013 11–3 122 20–2 131 032 21–2 22–1 13–2 040 22–2 132

8.32 6.33 6.05 5.78 5.35 5.18 4.69 4.61 4.52 4.16 3.957 3.820 3.806 3.712 3.643 3.517 3.444 3.406 3.308 3.299 3.279 3.177 3.138 3.026 2.968 2.905

10.62 13.98 14.62 15.33 16.55 17.11 18.90 19.22 19.60 21.34 22.45 23.27 23.35 23.95 24.41 25.30 25.85 26.14 26.93 27.00 27.17 28.06 28.42 29.49 30.08 30.75

0.02 −0.04 −0.08 0.01 0.06 0.01 0.03 −0.02 0.19 0.00 −0.04 −0.02 −0.05 −0.02 −0.02 −0.01 −0.03 −0.03 0.02 0.00 −0.06 0.01 −0.02 −0.03 0.00 −0.01

30.99 32.30 32.66 33.00 33.86 34.48 34.80 36.48 37.75 38.24 38.73 40.04 40.47 41.97 42.93 43.21 43.80 44.65 46.01 47.78 48.49 49.13 49.64 54.09 58.28

2.883 2.769 2.740 2.712 2.645 2.599 2.576 2.461 2.381 2.352 2.323 2.250 2.227 2.151 2.105 2.092 2.065 2.028 1.971 1.902 1.876 1.853 1.835 1.694 1.582

17 12 33 19 5 19 11 40 9 12 12 10 10 11 14 35 17 14 10 10 7 7 13 7 9

202 14–1 23–1 13–3 22–3 23–2 12–4 31–1 23–3 24–1 32–1 015 052 025 312 21–5 214 250 125 313 16–2 135 323 43–2 440

2.887 2.766 2.740 2.717 2.643 2.603 2.579 2.461 2.388 2.351 2.321 2.252 2.230 2.158 2.104 2.096 2.063 2.028 1.973 1.901 1.870 1.854 1.835 1.694 1.582

30.94 32.34 32.65 32.93 33.88 34.43 34.76 36.48 37.84 38.25 38.76 40.00 40.41 42.12 42.95 43.18 43.80 44.57 44.96 47.80 48.63 49.10 49.60 54.09 58.27

−0.05 0.04 −0.01 −0.07 0.02 −0.05 −0.04 0.00 0.09 0.01 0.03 −0.04 −0.06 0.15 0.02 −0.03 0.00 −0.08 −1.05 0.02 0.14 −0.03 −0.04 0.00 −0.01

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Kheïreddine et al.

34

Table IV. Powder diffraction data of BaTlP3O9. 2θobs

dobs

Iobs

Hkl

dcal

2θcal

Δ2θ

2θobs

dobs

Iobs

hkl

dcal

2θcal

Δ2θ

10.73 16.56 17.41 18.79 22.22 22.57 23.38 26.67 27.13 27.93 28.64 29.12 29.57 30.25 30.90 31.82 32.29 32.73 33.05 34.06 34.80 36.30 36.93 37.51 38.08 39.01 39.62 40.23

8.24 5.35 5.09 4.72 3.998 3.937 3.801 3.340 3.284 3.192 3.114 3.064 3.019 2.952 2.892 2.810 2.770 2.734 2.708 2.630 2.576 2.473 2.432 2.396 2.361 2.307 2.273 2.240

20 23 9 55 67 67 71 38 42 42 25 36 75 26 6 60 100 18 26 29 4 22 10 10 53 40 42 15

110 120 210 111 201 121 211 031 230 131 301 040 311 140 002 012 400 112 041 141 202 331 241 150 340 132 302 312

8.23 5.37 5.05 4.73 4.00 3.937 3.806 3.342 3.293 3.199 3.114 3.071 3.019 2.959 2.893 2.816 2.772 2.729 2.712 2.635 2.565 2.479 2.436 2.399 2.362 2.311 2.278 2.240

10.74 16.49 17.54 18.73 22.19 22.57 23.36 26.65 27.05 27.85 28.64 29.06 29.57 30.18 30.88 31.75 32.27 32.78 33.11 34.23 34.95 36.21 36.86 37.47 38.07 38.94 39.53 40.23

0.01 −0.07 0.13 −0.06 −0.03 0.00 −0.02 −0.02 −0.08 −0.08 0.00 −0.06 0.00 −0.07 −0.02 −0.07 −0.02 0.05 0.06 0.17 0.15 −0.09 −0.07 −0.04 −0.01 −0.07 −0.09 0.00

40.78 41.36 42.42 43.52 43.78 44.37 45.62 46.06 46.92 47.84 48.62 49.35 50.05 50.67 51.50 52.29 52.49 53.11 53.51 54.20 54.58 55.51 55.70 57.01 58.36 58.89 59.64

2.211 2.181 2.129 2.078 2.066 2.040 1.987 1.969 1.935 1.900 1.871 1.845 1.821 1.800 1.773 1.748 1.742 1.723 1.711 1.691 1.680 1.654 1.649 1.614 1.580 1.567 1.549

6 20 30 45 17 29 12 28 8 8 13 17 27 16 6 14 6 18 6 6 9 9 6 22 22 6 16

151 510 431 501 142 511 332 242 441 103 052 152 203 213 252 223 512 133 361 522 071 162 323 143 333 243 452

2.216 2.182 2.133 2.070 2.069 2.042 1.991 1.968 1.939 1.900 1.873 1.846 1.822 1.802 1.774 1.746 1.742 1.724 1.711 1.691 1.679 1.652 1.647 1.616 1.583 1.567 1.545

40.69 41.35 42.33 43.68 43.72 44.33 45.53 46.07 46.04 47.80 48.58 49.31 50.00 50.73 51.47 52.40 52.47 53.09 53.52 54.17 54.61 55.57 55.76 56.94 58.45 58.90 59.53

−0.09 −0.01 −0.09 0.16 −0.06 −0.04 −0.09 0.01 −0.88 −0.04 −0.04 −0.04 −0.05 0.06 −0.03 0.11 −0.02 −0.02 0.01 −0.03 0.03 0.06 0.06 −0.07 0.09 0.01 −0.11

is plotted in Figure 1(d), and the powder diffraction data for the compound are reported in Table IV. Averbuch-Pouchot, M. T. and Durif, A. (1986). “Crystal structure of barium cyclotriphosphate tetrahydrate, Ba3(P3O9)2·4H2O,” Z. Kristallogr. 174, 219–224. Belaaouad, S. (2002). “Contribution à l’étude des propriétés physico-chimiques, thermiques et vibrationnelles des cyclotriphosphates mixtes de cation alcalino-terreux MII-cation monovalent MI, MIIMIP3O9·xH2O (MII = Sr2+, Ba2+, MI = K+, Tl+ et NH+4 ) et manganèse ou nickel-cation MI, MIIMI4 (P3O9)2·yH2O (MI = Na+, Ag+ et NH4+),” Thèse d’Etat, Université Hassan II-Mohammedia, Faculté des Sciences Ben M’Sik, Casablanca, Maroc. Belaaouad, S., Sbai, K., Kenz, A., and Pierrot, M. (2000). “Chemical preparation, thermal behavior and crystal structure of ammonium barium cyclotriphosphate dihydrate,” Mat. Res. Innovat. 3, 352–359.

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Belaaouad, S., Sbai, K., Kenz, A., and Pierrot, M. (2001). “Chemical preparation and crystal structure of ammonium barium cyclotriphosphate dehydrate,” Ann. Chim. Sci. Mater. 25(4), 46–53. Belaaouad, S., Lahrir, Y., Sarhane, S., and Tridane, M. (2009). “Chemical preparation, thermal behavior, kinetic and infrared studies and quantum chemical calculations of Ba3(P3O9)2·6H2O,” Phos. Res. Bull. 23, 67–75. Jouini, A. and Durif, A. (1983). “Utilisation des résines dans la préparation des phosphates condensés,” C. R. Acad. Sci. Paris 297 II, 573–580. Louër, D. and Louër, M. (1972). “Automatic indexation of X-ray diffractograms by the program treor,” J. Appl. Cryst. 5, 271–275. Louër, D., and Vargas, R. (1982). “Refinement program treor,” J. Appl. Cryst. 15, 542–545. Sbai, K. and Belaaouad, S. (2003). “Chemical preparation, crystal structure, thermal behavior and IR studies of barium thallium cyclotriphosphate dehydrate,” J. Phys. Chem. Solids 64, 981–991.

Chemical preparation and XRD data for four cyclotriphosphates

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The history of the International Centre for Diffraction Data Julian Messicka) International Centre for Diffraction Data, Newtown Square, Pennsylvania

(Received 16 December 2011; accepted 29 December 2011) The International Centre for Diffraction Data has a colorful history, starting as a small task group of involved and interested scientists and progressing through a number of evolutionary steps that were required to deliver scientific products and services globally. The results of these efforts can be found in numerous scientific publications that focus on basic physics, method development, and analyses of the material identification of solid-state materials. This article examines the evolution of the organization through its members and employees. © 2012 International Centre for Diffraction Data. [doi:10.1017/S0885715612000085] Key words: International Centre for Diffraction Data, Joint Committee on Powder Diffraction Standards, Joint Committee on Chemical Analysis by X-ray Diffraction Methods

I. INTRODUCTION

III. FOUNDING YEARS: 1930S TO 1940S

Julian Messick started as an employee of the International Centre for Diffraction Data (ICDD) in 1966 and eventually became General Manager in 1984. J. Messick’s work as an employee, general manager, and eventually member of the board of directors brought him in regular contact with most of the founding members of the organization. He was personally involved with the key members, employees, and directors who shaped the organization for several decades. Indeed, J. Messick is considered an important contributor in the evolution of the ICDD as he organized the construction and design of the current ICDD facility, was in management during the critical transitions from paper to electronic products, wisely managed ICDD finances for decades, and hired and developed many employees who work at the ICDD today. In 2007, Tom Blanton, the ICDD Chairman of the Board of Directors, asked J. Messick to write about the history of the ICDD, focusing on the people and organizations that shaped it. This article is the result.

In the early twentieth century, many scientists including G.L. Clark (1932), F. Halla and H. Mark (1937), A. W. Hull (1919), Ewald and Herman (1931), and Wheeler P. Davey (1934) studied the aspects and utility of X-ray analysis (Hanawalt, 1986; Hanawalt and Rinn, 1986). All of these scientists made great contributions to the field of X-ray analysis, but little was done in establishing standards for general use. In 1937, the American Society for Testing and Materials (ASTM) conducted a symposium on radiology and X-ray diffraction methods (Hanawalt et al., 1938) where the importance of generating and producing adequate standards was brought forth and a joint subcommittee was established to address this issue. The membership of this subcommittee was drawn from the Committee on X-ray and Electron Diffraction, Division of Chemistry and Chemical Technology of the National Research Council; ASTM Committee E-3 on Chemical Analysis of Metals; ASTM Committee E-4, Subcommittee VI, on Metallography, and ASTM Committee E-7 on Radiographic Testing (Davey, 1941). W.P. Davey of the General Electric Company was designated as Chairman of the Joint Committee, and other members included: H.A. Bartrom, American Institute of Physics. H.W. Pickett, ASTM E4 and General Electric Company. W.L. Fink, Aluminum Company of America (ALCOA). M.L. Fuller, New Jersey Zinc Company. J.D. Hanawalt, the Dow Chemical Company. V. Hicks, Navy Department. M.L. Huggins, Eastman Kodak Company. P.F. Kerr, Columbia University. J. Magos, Crane Co. H.R. Nelson, Battelle Memorial Institute. W.E. Richmond, U.S. Geological Survey. L.L. Wyman, General Electric Company. It is highly probable that this first meeting of the newly formed Joint Committee was the beginning of the Joint Committee on Chemical Analysis by X-ray Diffraction Methods. “The initial role of the Joint Committee was to approach industrial and scientific organizations for support and to initiate a structure for overseeing this activity” (Smith, 1986). About this time, it was becoming known that several individuals were working with or constructing limited,

II. THE ICDD

The International Centre for Diffraction Data (1978– current) The Joint Committee on Powder Diffraction Standards (1970–1978) The Joint Committee on Chemical Analysis by X-ray Diffraction Methods (1941–1970) The ICDD adopted several names over a span of many years. In each case, the name change clearly reflected the ICDD’s expanding mission as it constantly worked to satisfy the growing needs of the X-ray diffraction community. At present, the ICDD clearly states that its mission shall be “to continue to be the world center for quality diffraction and related data to meet the needs of the technical community. The ICDD promotes the application of materials characterization methods in science and technology by providing forums for the exchange of ideas and information.”

a)

Electronic mail: [email protected]

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Powder Diffraction 27 (1), March 2012

0885-7156/2012/27(1)/36/9/$18.00

© 2012 JCPDS-ICDD

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smaller files of diffraction data to satisfy their specific work requirements. Through the efforts of this Committee, “contributed data was solicited from workers in various laboratories in advance or in lieu of publication.” William L. Fink and K. Van Horn of ALCOA, M.L. Fuller of the New Jersey Zinc Company, and C.H. Hogg of the Pennsylvania State University were generous contributors (Davey, 1941). A substantial amount of the card data for the first ASTM data card set was from J. Donald Hanawalt, Harold W. Rinn, and Ludo K. Frevel of The Dow Chemical Company and reproduced from Dow’s original card set (Hanawalt et al., 1938). Until 1938, and well after, diffraction films were retained as the permanent record of X-ray pattern characteristics (Blanton, 2003). With the publication of the classic article, “Chemical analysis by X-ray diffraction” (Hanawalt et al., 1938), a new presentation of data, in table form, was introduced, along with a method of searching the file to retrieve data. “Reprints of the publication were quickly exhausted and the General Electric Company sponsored a second printing of 500 copies. Even this printing was insufficient. In 1941, the ASTM issued the data sets on 3 × 5 cards. This issue became Set 1 of the Powder Diffraction File” (Davey, 1941). This publication has long been considered the official beginning of the Powder Diffraction File (PDF, 1941) and the ICDD. The year 1942 marked the first appearance of an Alphabetical Index. The index was contributed to the ASTM by two organizations: the F.P. Hochgesang, Research and Development Division of Socony-Vacuum Oil Co., Inc., and M. Stevens and J.B. Reed of the Frankford Arsenal (Davey et al., 1942). In 1944, a Supplemental Card Set was published by the ASTM. Mineralogical data were furnished by F.A. Bannister of the Department of Natural History of the British Museum and by the Crystallographic Laboratory of the Cambridge University. The work of the British Institute of Physics, through Sir Lawrence Bragg and A.J.C. Wilson, was extremely valuable. Considerable use was made of the resumes of G.S. Harcourt, American Mineralogist, Vol. 27, and A.K. Boldyrev et al., Annales del Institute des Mines Leningrad, Vol. 11 (Davey, 1944). W.P. Davey conducted years of scientific research at the General Electric Company, and, in later years, he joined the staff of the School of Chemistry and Physics at the Pennsylvania State College. W.P. Davey carried on his efforts to establish a file of X-ray diffraction standards while serving as Chairman of the Joint Committee. It has been reported that significant financial support by the General Electric Company was provided to the Pennsylvania State University as a grant so that W.P. Davey could continue this work (Wyman, 1966). W.P. Davey retired from Pennsylvania State College (now renamed Pennsylvania State University) in 1949, but retained his office and continued his contributions to the X-ray community. His assistant, Art S. Beward, assumed increasing responsibility and moved the production of the PDF (using hand-cut paper strips) to a house on Heister Street in State College, Pennsylvania, where it remained until the organization introduced computers in about 1963. The collaborators in publishing Set 1 of the Card File, in addition to the Joint Committee of the ASTM, were the Committee on X-ray and Electron Diffraction of the Division of Chemistry and Chemical Technology of the (USA) National Research Council and the British Institute 37

Powder Diffr., Vol. 27, No. 1, March 2012

of Physics. The British Institute of Physics, which had previously proposed a similar activity, polled its work with that of the Joint Committee. In practice, the application of this Card File proved somewhat cumbersome. There were no “Search Manuals” as we became accustomed to in later years. Searching the file was accomplished using data cards. The three strongest lines of a diffraction pattern were also listed on two other cards on which the second and third strongest lines, respectively, were listed first. “This arrangement was devised to use the search scheme proposed by J.D. Hanawalt, H.W. Rinn, and L. Frevel (Hanawalt et al., 1938). By placing the cards in a drawer in ‘Hanawalt’ order, the user could thumb through the cards examining index lines to find a match. As the number of cards increased with Set 2 (1944) and Set 3 (1949), the stack of cards became quite large. The larger number of entries in the Card File made it more useful because of increased coverage, but it was cumbersome to use for the identification of unknown materials” (Jenkins and Smith, 1996). In the preface of the first Card File, a note appeared stating, “The Hanawalt Method is described rather fully in Industrial and Engineering Chemistry, Analytical Edition, 1938.” Subcommittee VI of ASTM Committee E-4 has issued a Tentative Recommended Practice for the Identification of Crystalline Materials by the Hanawalt X-ray Diffraction Method. It should be studied by all users of this Card File. The article by Hanawalt et al. (1938) did not take long to revolutionize the efforts in building a file of X-ray diffraction standards and a method of data retrieval. Industrial and Engineering Chemistry stated that it “considers itself fortunate in being able to present a complete, new workable system of analysis, for it is not often that this is possible in a single issue of any journal. Several qualified reviewers assure us that the authors present here a method that is not only workable but so clearly described that their scheme of chemical analysis will be readily understood by all those familiar with X-ray diffraction. The reader does not need to be skilled in crystal analysis; only to be familiar with the bare principle of diffraction. There is reason to believe that this publication, which is made possible in this form by the generous financial assistance of the Dow Chemical Company, will serve to bring this method of analysis into general use in industrial and consulting analytical laboratories” (Hanawalt et al., 1938). Hanawalt et al. (1938) wrote, “This paper supplies tabulated data on the diffraction patterns of 1000 chemical substances and gives a scheme of classification which makes possible a routine and valuable use in the chemical laboratory”. In 1919, Hull emphasized the experimental simplicity of obtaining the diffraction pattern of a substance and the fact that it requires only a minute amount of material. He stated that, “every crystalline substance gives a pattern; that the same substance always gives the same pattern; and that in a mixture of substances, each produces its pattern independently of the other.” The author states, “However, as yet, no extensive use has been made of X-ray diffraction. Probably one of the most important circumstances, which at present handicap the general use of the method, is that an adequate file of standard patterns is not available for reference. The method being empirical, standards are necessary.” The author also stated, “The use of the X-ray method of analysis would be greatly extended if crystal structure workers, after they have taken The history of the International Centre for Diffraction Data

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care to get a pure material, would publish the powder data of the material in the same or equivalent form” (Hull, 1919). Hanawalt et al. (1938) also discussed an index book currently in use at the Dow Chemical Company. Lines that lie between 20 Å and 0.5 Å for indexing are grouped into 77 suitable divisions. Each of the divisions of the index is followed by a section called the Supplementary Group Index in which all patterns whose strongest line falls in the major group have their three strongest lines listed in the order 1, 2, 3. All patterns whose second strongest line falls in the major group have their three strongest lines listed in the order 2, 1, 3; and all patterns whose third strongest line falls in the major group have their three strongest lines listed in the order 3, 1, 2. In 1942, W.P. Davey introduced an Alphabetical and Formula Index that listed, in a modified alphabetical order, the chemical names of substances represented in the first set of data cards. Each name was followed by its chemical formula and by a statement of the strongest line in the X-ray pattern. In 1945, in the second release of the Alphabetical Index, the second card set was included, and the index was modified with the three strongest lines in accordance with the Hanawalt Method (Davey, 1945). By the 1950s, an Alphabetical Index, a Grouped Numerical Index (Davey, 1952), and a Mineral Listing were published with the fourth set of cards. “There were three sections to the Alphabetical Index. The first and largest section listed the Inorganic compounds and elements; the second listed Organics and the third listed Minerals. In the Numerical section, for every data card in the File, the entry in the Index consisted of the three strongest lines of the pattern, their intensities, the chemical name and formula of the substance and the numerical sequence number of the data card. Each data card would have three entries in the index depending on the three strongest lines.” The indexes, because of their size, were now published as hardcover books. This was truly the beginning of the PDF as we know it today or, at least until the onset of the computer age. The preparation and production of the PDF, soon after the format for data cards and index books was agreed upon by the (ASTM) Joint Committee, proved to be laborious, expensive, and time consuming. Initially, the first few sets of data cards were handwritten and no index books were available. The Alphabetical Index was prepared by typing strips of one-line entries with the three strongest lines, the chemical formula, and the PDF number for each compound. The Hanawalt Numerical Index provided for the permutation of the three strongest lines. The typed strips were then ordered in a Termitrex holder and then photographed for printing. The Termitrex holder was a metal frame about 15 inches by 20 inches that permitted the insertion of typed strips of data in slots that were provided in the back of the frame assembly. Each time a page was complete, it was photographed for printing and the next page assembled in the same manner. IV. BECOMING A BUSINESS: 1950 TO 1970

Until this time, the editorial work on the PDF was accomplished under the direction of W.P. Davey at the Pennsylvania State University. By the late 1950s, G.W. Brindley of the Pennsylvania State University was assigned the role of Editor. Somewhere around 1960, L.G. Berry of the Department of Mineralogy, Queen’s University, Kingston, Ontario, Canada, was designated Editor of the PDF. H.W. 38

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Rinn was Chairman of the Joint Committee, having served in this capacity since 1956. The PDF was becoming selfsupporting through its sales and soon, under the direction of A.S. Beward, the offices of the Joint Committee, including the technical and data acquisition activities, moved from the Pennsylvania State University to Heister Street in downtown State College, Pennsylvania. By the early1960s, the entire activity was moved to the ASTM Headquarters at 1916 Race Street in Philadelphia, Pennsylvania, initially under the direction of A.S. Beward and later J. Caum and Sam Etris. As gathered from conversations with a few of the early members of the Joint Committee, the move was probably required since the Joint Committee appeared to be a viable business activity with increasing business and production demands. A.S. Beward played a vital role in the activities of the Joint Committee at the Pennsylvania State University, the office in downtown State College, and, for a few years, at the location at ASTM Headquarters. Joseph V. Smith of the Department of Mineralogy at the Pennsylvania State University soon assumed the duties of Editor of the PDF. A unique feature of the Joint Committee was that it was a quasi-independent organization. The Joint Committee managed and directed all activities concerned with the PDF and always retained the proceeds from its sale. The ASTM furnished accounting and logistical support, provided office space, hired employees, marketed the product, and arranged for printing of the Joint Committee’s products. In other words, the ASTM provided all the services necessary to operate a business. The Joint Committee, naturally, on a monthly basis, reimbursed the ASTM for all costs incurred. As the PDF began to gain recognition, the scientific community requested regular, more frequent issues of the sets of data and the publication of better quality data. To meet this challenge, data acquisition activities had to be increased. Mary Lotz became Bibliographer of the Joint Committee and took on the task of searching the scientific literature. This activity was conducted at the Pennsylvania State University because of their excellent library facility and extensive collection of scientific journals. To improve the overall quality of data, a “type” of grant-in-aid program was established through the effort of A.J.C. Wilson of the University of Birmingham, Birmingham, England. It was agreed upon by the Joint Committee that, in lieu of actual cash funding to support the production of high-quality X-ray patterns for inclusion in the PDF, printed sets of the PDF would be supplied for sale in the United Kingdom. The proceeds from the sale were then used to support the generation of highquality patterns at cooperating universities. (The author believes that after World War II, it was very difficult to get British pounds out of the country, and this was a solution to that problem.) A few of the participants included: University College, Cardiff, Wales; University of Leeds, Leeds, England; University of Durham, Durham, England; ARC Unit of Structural Chemistry, London, England; Rothamsted Experimental Station, Harpenden, Hertz, U.K.; and the University of Aberdeen, Old Aberdeen, Scotland. An Associateship was established in 1953, under the direction of Howard F. McMurdie, at the National Bureau of Standards (NBS), Gaithersburg, Maryland (Mighell et al., 2004). The mission of the Associateship was “to collect data under controlled and reproducible conditions, to provide d–I data on common important compounds, to replace multiple Messick

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entries in the earlier sets, and to improve the overall accuracy of the PDF” (Jenkins and Smith, 1996). Following H.F. McMurdie as Director, this activity was carried on for many years by Stanley Block and Camden Hubbard. Members of the Associateship included Eloise Evans, Marlene Morris, Johan De Groot, Winnie Wong-Ng, and Boris Paretskin. Through the years, the powder patterns produced by the Associateship were regarded as being of the “highest quality.” The NBS, in conjunction with the Associateship, also published the NBS Monograph Series that included most of this work from 1953 to 1985. In Release 2011 of the PDF-4 + , 493 reference patterns were published through the Circular 539 series (Swanson and Tatge, 1953) and another 1473 patterns were published through the NBS Monograph 25 series. Even under 2011 quality standards, and more than 25 years after they were produced, 57% of these patterns are still receiving ICDD’s highest-quality designation (Kabekkodu, 2011). In 1961, W.L. Fink assumed the duties of Chairman of the Joint Committee. Under the direction of W.L. Fink and J.V. Smith, the Joint Committee made outstanding progress over the intervening years. Through the effort of W.L. Fink and Professor Y. Takeuchi of the University of Tokyo, the Japanese Powder Data Commission was established. This program paralleled the activities of the Associateship at the NBS in producing high-quality data for inclusion in the PDF. Pieter M. DeWolff and Jan Visser, Technisch Physische Dienst, TNO-TH, Delft, Netherlands, are also recognized for being outstanding contributors of quality data to the PDF through the ICDD Grant-in-Aid Program. Over the last 10 years, the ICDD through its Grant-in-Aid Program has disbursed over $3 million to numerous universities and colleges worldwide. This program must be considered one of the best investments the Joint Committee has ever made. Grantees, once established, improve with experience and have an excellent record for producing the highest-quality data sets. Professor Shao-Fan Lin from the People’s Republic of China recently became the second grantee to publish over 1000 material data sets in the PDF, joining Larry Calvert of the National Research Council of Canada. In the 1960s, to process the increasing influx of data that was being acquired and to maintain high-quality data for publication, the Joint Committee realized the need for additional editorial assistance. Benjamin Post of the Polytechnic Institute of Brooklyn and Sigmund Weissmann of Rutgers University were engaged as Associate Editors of the PDF. B. Post reviewed inorganic and organic materials and S. Weissmann reviewed metals and alloys. J.V. Smith reviewed all mineral data. L.G. Berry, Deane K. Smith, Peter Bayliss, and Mary Mrose also served as Mineral Editors during this period. To supervise the day-to-day operations at the ASTM (with about 10 staff) and to serve as liaison with the ASTM management and the Joint Committee members, Rodger G. Simard was hired as Corporate Secretary and General Manager. Soon after the move to the ASTM Headquarters, work commenced on revising the original five sets of data. With an editorial staff now established, and the need to update data in the original publications, this project was considered absolutely necessary. The project was completed in the early 1960s and plans were formulated to eventually revise Sets 6–10. In addition to the data cards, the 1960s introduced the PDF in “keysort cards.” These cards consisted of holes representing 39

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“d” values in which long needles were inserted to obtain data of interest. This product was eventually discontinued because of exorbitant production costs. The Matthew Index was also discontinued at this time because it had reached the maximum number of patterns it could accommodate. In the 1960s, the data sets approached and exceeded 10,000 entries, making several manual methods impractical (taking too much time), especially those like the Matthew Index that required many pieces of information to perform a search. In today’s world, with the computing power of modern PCs, some of these limitations have become advantages and multivariable searches are often combined into data mining algorithms. There were very few total members, and actually fewer than 10 people did the work of the organization. When the various committees met, the same people simply changed chairs and rehashed the same topics! Many of the Joint Committee Annual Meetings were held concurrent with the Pittsburgh Diffraction Conference in 1960–1970 (when A.S. Beward was the principal worker at State College, Pennsylvania). In the 1965 annual meeting, held concurrent with the Gatlinburg ACA, Bill Parish, another Pennsylvania State University graduate, questioned the Treasurer about finances. The Treasurer did not like being questioned, and walked out! The organization had no budget that year! When the organization moved to the ASTM Headquarters in Philadelphia, some new members and workers helped to improve the organization (Fred Van Atta, Joe Smith, Andy Danko, L.G. Berry, Ben Post, Sig Weissmann, and Gerald G. Johnson). Professor Wilbur (Will) Bigelow, a graduate of the Pennsylvania State University, addressed the identification problem of not using intensities for the construction of a search index. Will was using electron diffraction where the diffraction intensities were not as meaningful as with X-ray diffraction. His work was the basis for the Fink Index. Over the years, Prof. Hanawalt would claim that the Hanawalt method of identification could do everything that the Fink Index used. Hanawalt simple said; “It just takes more work.” They were both at the University of Michigan and did not interact; G.G. Johnson was the channel between them. The Fink and Hanawalt indexes are still used in manual methods and have been adopted in computer-automated searches; both methods can excel with certain classes of materials. The Fink method works best with materials having larger unit cells and “long” d-spacings. Another solution to the Matthew Index was proposed by Dr. Jan Visser of Delft, Netherlands. For several years, Dr. Visser’s group in Delft attempted research funding using holographic techniques. Although nothing came of this research for the Joint Committee on Powder Diffraction Standards (JCPDS), many other funded projects formed the basis of other scientific diffraction activities. Starting in the mid-1960s, computer technology made great advancements in data processing and retrieval techniques. Vladimir Vand and Gerald G. Johnson, Jr., of the Pennsylvania State University soon began to investigate the application of data processing for the PDF. Not only were search/match programs being developed, but also the master copy of the book index was printed at the Pennsylvania State University. The final pages were then carefully shipped to professional print shops to produce the various search manuals! The JCPDS had special print trains cast by IBM so that Greek, superscript, subscript, and italic fonts could appear in The history of the International Centre for Diffraction Data

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the search manuals. This work was of vital interest to the Joint Committee because the Hanawalt Numerical Index and the Davey Alphabetical Index were distributed with each set of the PDF. As mentioned previously, both indexes were produced manually, resulting in lengthy production times and considerable expense. The research by V. Vand (who died in 1968) and G.G. Johnson was eventually supported by the Joint Committee Grant-in-Aid Program and continued for many years under the direction of G.G. Johnson. A great interest was developing in the scientific field for automated searching of chemical databases Johnson and Vand (1967) also directed their efforts in this area. At the 1965 Pittsburgh Diffraction Conference, Dr. Ludo Frevel of the Dow Chemical Company (Frevel, 1965), Mr. Monte Nichols of Lawrence Livermore Laboratories (Nichols, 1966), and G.G. Johnson of the Pennsylvania State University each presented a different computer search match program for the identification of multiphase powder diffraction patterns. The Joint Committee distributed the mainframe software, written by G.G. Johnson, without change until the PC appeared. G.G. Johnson rewrote the mainframe software for IBM, UNIVAC, CDC, and Honeywell-type computers over the next 15–20 years. The entire set of d–I pairs in the data sets were independently keyed by the personnel at the Pennsylvania State University, and, unknowingly, also at 3M (under the supervision of Dr. Byron T. Gorres). This allowed a computerized comparison of the two independent data set entries to reduce data entry errors. At the 1974 Berkeley American Crystallographic Association (ACA) meeting, the scientific community asked for the magnetic tape to be reorganized from two separate files (the first with chemical names and formulae and the second with d–I pairs) into a single file with the merged information available in a linear manner. It should be remembered that magnetic tapes were the principal storage media for computers; the massive high-speed disks of today were only available at national data centers. The tasks at hand were not simple considering that the starting point for this work was to create a computer-readable file from the existing PDF, to write the computer programs to produce the indexes, and to write programs to search the PDF for the identification of unknown materials. All of this work started with the tremendous task of keypunching the PDF on “IBM” cards. Over time, the difficulties were overcome and the first computer-generated indexes appeared in 1964. Soon thereafter, V.V and and G.G. Johnson developed the PDF on magnetic tape, with associated search programs. To satisfy copyright concerns, the product was only made available on lease. This work was eventually transferred from the Pennsylvania State University to the staff at the ASTM Headquarters. G.G. Johnson continued working for the Joint Committee at the Pennsylvania State University as a computer consultant. The creation of a computer-readable database not only led to the development of other products, such as the PDF on “IBM” cards, 2dTS, a computer time-sharing system, the Fink Graphical Index and the Fink Numerical Index, but also paved the way for the development of products that we know today and provided the impetus to remain “state-of-the-art” in this activity. The early computer programs were very different from those in use today. Several limitations were fundamentally 40

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based on the small storage capacity and limited processors of existing computers. Many automated indexes were developed that use small portions of the data files to automatically process data sets. In fact, one of the early programs designed for a laboratory computer, instead of a company mainframe (Frevel et al., 1976), was designed for single peak search on a small number of 298 common phases. This number was selected from the historical records of phases that were important to the Dow Chemical Company. J. Messick joined the staff at the ASTM Headquarters in 1966 as Assistant to the General Manager, and, in a few years, W. Frank McClune joined the staff as Manager of the Diffraction Data Department. A governing group was established, with W.L. Fink serving as Chairman of the Joint Committee. Other members included R.G. Simard, L.L. Wyman, J.D. Hanawalt, J.V. Smith, and A.W. Danko. L.L. Wyman served as Treasurer and, for the most part, J.V. Smith organized and managed the technical activities. Over the next several years, the overall administration of the Joint Committee improved dramatically. During this period, the editorial, bibliographic, and publication functions began progressing favorably and the annual updates to the PDF consisted of 2000 patterns per set. As more and more individuals and industrial concerns became familiar with the Joint Committee, the membership steadily increased. Around 1940, there were perhaps 15 members; by 1950, at least 25 members, and in the 1960s, the membership increased to approximately 70 members. With increasing membership, the organization required at least one meeting a year to discuss technical and editorial issues. Financial issues were discussed to a lesser degree. Three committees were eventually established—the Editorial Committee, the Technical Committee, and the Finance Committee. In 1969, Tom Marshall, Executive Director of the ASTM, passed away and William Cavanaugh was recruited to serve as the ASTM’s new Executive Director. From the onset, Cavanaugh objected to the quasi-independent status of the Joint Committee while operating at the ASTM Headquarters. At the same time, the Joint Committee was in the process of being incorporated as a nonprofit corporation in the Commonwealth of Pennsylvania. In December 1969, the incorporation was approved by the Pennsylvania Department of State and the Joint Committee became a “Nonprofit Corporation in the Commonwealth of Pennsylvania,” exempt from taxation under section 501(c)3 of the Internal Revenue Code. The incorporators were W.L. Fink, J.D. Hanawalt, R.G. Simard, Morris R. Brooke, and L.L. Wyman. The first directors, who were collectively designated as the Board of Directors and served at the first annual meeting, were A.W. Danko, W.L. Fink, J.D. Hanawalt, H.W. Rinn, R.G. Simard, D.A. Vaughan, and L.L. Wyman. Naturally, the incorporation of the Joint Committee required appropriate organizational changes. Of primary importance was the establishment of a set of bylaws to officially describe the organization’s mission and outline how the organization would conduct its affairs. Topics such as Membership, Meeting of Members, Election of Officers and Directors, Committees and Subcommittees, Proxies, Quorums and Voting Requirements, and many additional areas had to be addressed. M.R. Brooke, while serving as the Joint Committee’s legal consultant, prepared the first set of bylaws. Through the years, numerous revisions of the bylaws have Messick

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been required to accommodate the ever-changing activities of the Joint Committee. V. INTERNATIONAL GROWTH: 1970 TO 1990

By 1970, the objections of the Joint Committee’s status and other issues raised by W. Cavanaugh necessitated decisive action by the relatively new Joint Committee Board of Directors. The Board of Directors announced that the Joint Committee would vacate the ASTM Headquarters located at 1916 Race Street, Philadelphia, Pennsylvania, and conduct operations at the Mutual Benefit Life Building, 1845 Walnut Street, Philadelphia, Pennsylvania. The new office facilities were located on the 20th floor, overlooking Rittenhouse Square. In less than two years, the Joint Committee acquired a new building in Swarthmore, Pennsylvania. Soon after the move to the “permanent” Headquarters in Swarthmore, J.D. Hanawalt proposed that the organization’s name be changed to the “Joint Committee on Powder Diffraction Standards” (JCPDS) in order to more accurately reflect the mission and purpose of the organization. The proposal was unanimously approved by the Board of Directors. In 1978, J.D. Hanawalt, again, proposed that the name of the corporation be changed. The JCPDS–ICDD was approved and adopted to better reflect the international scope of operations. At J.D. Hanawalt’s insistence, new members were brought into the organization. One of these new members was Walter Eysel, a visiting professor at the Pennsylvania State University, who was eventually a key figure in the German diffraction community and worked at the historic Heidelberg University. G.G. Johnson introduced the following distinguished members of the organization: Herb Goebel, winner of the 1998 Hanawalt Award. Shao-Fan Lin, chief scientific liaison in China, Distinguished Grantee 2004. Sergei Kirik, Distinguished Grantee 2007, from Krasnoyarsk, Russia. In 1968, D.K. Smith left Lawrence Radiation Laboratory and joined the Pennsylvania State University faculty. He spent well over half of his time on efforts for the Joint Committee, until the time of his death in 2001. D.K. Smith and G.G. Johnson worked together for more than 40 years on computer software for powder diffraction. With the increasing membership participation in business and technical activities, the growing user base, and the need to continue to produce the best products possible, it soon became apparent that the internal operating procedures at the Headquarters had to be further developed. Through the efforts of G.G. Johnson, consultant for computer activities, Mark Holomany was recruited and joined the ICDD’s staff as Manager of the Computer Department with the primary mission to adapt editorial activities to the newly acquired “VAX” computer. Up to this point, the search indexes were computer-generated, but data cards continued to be typed onto 6 × 9-inch formatted sheets using IBM Selectric typewriters. Typing a single card required changing the symbol head numerous times, and proved to be time-consuming and inefficient. Through the guidance and expertise of Camden Hubbard, the Diffraction Data Department became equipped with Hewlett Packard terminals, which permitted input of data directly to the computer. Shortly thereafter, software was obtained to automate the sales, finance, and accounting 41

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activities. Within a few years of the introduction of the personal computer, the entire Headquarters’ operation was considered state-of-the-art, a level of operation that continues to be maintained today. In 1973, with the closing of the Westinghouse Astronuclear Laboratory in Pittsburgh, Pennsylvania, A.W. Danko, through the influence of L.L. Wyman, was added to the staff of Joint Committee as Special Consultant to the General Manger. With the decreasing employment at the U.S. Steel Corporation, Leo Zwell, also through the influence of L.L. Wyman, was added to the Headquarters’ staff as Assistant Bibliographer. W.L. Fink relinquished his position as Chairman of the Joint Committee in 1974 and L.L. Wyman was elected Chairman and served for a year. R.G. Simard, Corporate Secretary and General Manager since 1964, retired and A.W. Danko was selected to fill the position. With the passing of L.L. Wyman in 1975, Jesse W. Caum, formerly Technical Director at the ASTM, was appointed to fill the unexpired term of L.L. Wyman. At the next scheduled election in 1976, J.D. Hanawalt was elected Chairman and was followed by D.K. Smith in 1978. Shortly after A.W. Danko passed away, J.W. Caum was appointed Corporate Secretary and General Manager. W.F. McClune was appointed Editor of the PDF. To assist with the increasing editorial workload, Theresa Maguire was added to the staff in 1977 as Assistant Managing Editor, Donna Barry in 1979 as an accountant, and Terry Kahmer in data entry in 1981; all three are department managers today. In 1973, Gregory J. McCarthy of the Pennsylvania State University, and later of the North Dakota State University, was elected as Member-at-Large of the Board of Directors and while serving on the Board, was appointed Chairman of the Technical Committee. Over the next 14 years, G.J. McCarthy served on the Board in various positions under the W.L. Fink, L.L. Wyman, J.W. Caum, J.D. Hanawalt, and D.K. Smith administrations. He was elected as Chairman in 1982. In 1975, database sales first exceeded one million dollars and sales steadily grew during the decade. J. Messick was appointed as Corporate Secretary and General Manger in 1984, and, approximately a year later, Ron Jenkins joined the staff as Principal Scientist. G.J. McCarthy’s organizational and management skills were put to use to establish a new sense of direction for the ICDD in all areas of operation. As Chairman of the Technical Committee, he focused on new areas of interest and products by establishing subcommittees whose members were selected relative to their fields of interest. Early on, only a few subcommittees existed, but over time it was standard practice to take advantage of the membership’s expertise and willingness to volunteer. With the considerable growth in membership interest and participation, the number of subcommittees increased dramatically. The list of active subcommittees is constantly being updated to satisfy the ever-changing activities within the ICDD. Also, during G.J. McCarthy’s term as Chairman, a similar program of extending the activities of the Board of Directors was completed. The Awards, Employee Benefits, and the Long-Range Planning Committees were established. The Finance Committee also added the Budget Review Committee and the Marketing Subcommittee. It now appeared that the ICDD was a well-administered organization and, for The history of the International Centre for Diffraction Data

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the most part, many of the programs, policies, and procedures developed at this time are still practiced today. Several outstanding contributors to G.J. McCarthy’s administration were R. Anderson, J. Edmonds, W. Eysel, T. Fawcett, G. Fischer, C.M. Foris, G.P. Hamill, H.D. Hitchcock, C.R. Hubbard, R. Jenkins, G.G. Johnson, H.F. McMurdie, B. Post, M.C. Nichols, D.K. Smith, R.L. Snyder, L. Frevel, and J.W. Visser. The G.J. McCarthy era is best defined as a period of necessary growth. In addition to essentially restructuring the ICDD, he greatly expanded the scope of activity by instituting a program of tutorials and workshops that were an immediate success. One of the first programs presented was at the Denver X-ray Conference (DXC) at the University of Denver. “The organization and sponsorship of the Conference was administered by the University of Denver until 1997. Beginning in 1998, the ICDD assumed ownership of the Conference from the University of Denver. Each year, the technical program of the DXC is created and monitored by the Denver X-ray Conference Organizing Committee (DXCOC). The Committee consists of specialists from various fields of X-ray analysis, each of whom contribute[s] their expertise to the technical program. Today, this activity is conducted worldwide. While exhibits have become a large attraction at the Conference, DXCOC maintains a commercial-free, vendorneutral program. Working in partnership with the DXCOC, [the] ICDD manages the financial aspects of the Conference and its administration, including the exhibition of X-ray products and publication of the conference proceedings, Advances in X-ray Analysis” (Maguire, 2010). The ICDD was also a major participant in the annual meeting, technical presentations, and exhibits of the Australian X-ray Analytical Association. ICDD member Brian O’Connor of the Curtin University of Technology was among the early organizers of this conference. The ICDD also participates in the European Powder Diffraction Conference (EPDIC). ICDD members, Herbert Goebel, W. Eysel, J.W. Visser, and R.L. Snyder, were among the first EPDIC organizing committee. Similarly, ICDD members have been influential in the organization the South American X-ray Conference (SARX). Each conference promotes materials analysis and provides educational workshops to both novices and experts. The ICDD continues to provide both technical assistance in the form of workshops and financial assistance to these organizations. G.J. McCarthy stepped down as Chairman in 1986 and D. K. Smith was elected, once again, as Chairman. Note that with the exception of the first three chairmen, D.K. Smith is the only one to have served as Chairman on two different occasions for a total of eight years. One of the highlights of the D.K. Smith administration was the introduction of the NBS*AIDS83 review program. The potentially acceptable d–I data were keyed into computer-readable form and both the data and the NBS*AIDS83 output were supplied to Associate Editors. The NBS*AIDS83 program provided the editors with sufficient information to make a final decision on the appropriateness of the new data for the PDF and to assign the quality mark of the pattern. D.K. Smith also solicited the cooperation from other database organizations such as Fachinformationszentrum Karlsruhe (FIZ), to obtain additional information on existing patterns in the PDF and to explore other sources of data availability. The POWD 42

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program, developed by D.K. Smith, has been used to calculate hundreds of thousands of powder patterns for the PDF. For several years, computer-readable versions of the PDF, known as PDF-1, were available and contained d–Is, chemical formulae, and PDF numbers on magnetic tape. However, most laboratories used manual methods with indexes and card files. In 1985, PDF-2 was introduced, displaying all the data that appeared on a card image in computer-readable form. X-ray manufacturers were greatly interested in computer searching the PDF and most of the manufacturers of X-ray equipment were introducing automated systems. The early major suppliers of APD systems included Philips Electronics, the Diano Corporation, Siemens, and the Rigaku Corporation. The APD brought the electronic search process from a mainframe computer and into the laboratory. Material Data, Inc. (MDI) was a major supplier of software for automated systems incorporating the PDF. Over the next few years, the cooperation between the ICDD and equipment manufacturers and software developers proved to be very rewarding and the cooperation continues today as new products are produced. Sanyo Shuppan Book Company, and, in later years, Sanyo Information Systems, under the direction of Toshimichi Matsukura, proved to be an exceptional distributor of ICDD products in Japan and the Far East. During the second term of the D.K. Smith administration, he and R. Jenkins collaborated to produce and publish, Powder Diffraction, an international journal of materials characterization. The journal has proved to be a valuable source of information to all working in the field of X-ray diffraction. Ting Huang has been Editor-in-Chief of Powder Diffraction since 1999. In 1985, R. Jenkins, a world-renowned expert in XRD and XRF, long-time ICDD member, and development scientist at Philips Electronics in North America, joined the ICDD staff. This coincided with the closure of Philips research facilities in the United States. R. Jenkins was aware of an exciting new technology being developed by Philips at their main research facilities in the Netherlands, the CD-ROM. He was very influential in convincing the ICDD’s Board of Directors to investigate this new technology and then adapted it as a database media. He had a very able partner in Editor-In-Chief Frank McClune and they quickly adapted the PDF on a CD-ROM at the critical period when APD’s were transitioning to personal computers. Initially, both the ICDD and Philips (Netherlands) developed the concept of placing the total PDF on a single read-only media. For approximately three years in the mid-1980s, the ICDD not only sold the database but also distributed the CD-ROM drive and instructions on how to use both the CD-ROM drive and the database. Eventually, CD-ROM drives became common on PCs and the ICDD produced the database exclusively. The convenience of this new technology was quickly adapted and, within a few years, CD-ROM sales supplanted sales from all other media: books, cards, VAX tape, and microfiche. Because of the drop in sales and expense of manufacturing, in 1987 the production of cards was stopped, but a book in card format continues to be produced today. Over the next 10 years, global sales doubled from US $2 million to $4 million. VI. COLLABORATIONS: 1990 and beyond

L. Frevel was elected Chairman in 1990 and the ICDD continued to experience growing acceptance of its products. Messick

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In 1991, L. Frevel made a significant financial contribution to the ICDD for the establishment of a Crystallography Scholarship Fund to “encourage promising graduate students to pursue crystallographically-oriented research.” For many years, he continued his guidance over the program and today, to honor this pioneer in the science of X-ray diffraction, this fund is known as the Ludo Frevel Scholarship Fund. From 1991 until 2011, with the additional financial assistance from the private and industrial sectors, the ICDD has awarded 122 scholarships totaling over US $282,550. All scholarships are funded from the principal and today the fund is sufficient to award 13 scholarships annually. All donations to the fund go toward the scholarships. L. Frevel served only two years as Chairman and, by 1992, the Headquarters staff had increased considerably to meet the demands of the rapidly growing product line, the increasing membership, and increasing marketing and technical activities. This business growth led to the demand for an expansion in office space. Shortly before the completion of his term as Chairman, L. Frevel suggested that the ICDD investigate the possibility of obtaining a larger office facility. L. Frevel appointed a committee of J. Messick, G.G. Johnson, G. Hamill, and G. Fischer to conduct the search. G.G. Johnson was elected Chairman in 1992 and, in a short period of time, property was acquired in Newtown Square, Pennsylvania. Over the next year, the facility at 12 Campus Boulevard was designed and constructed and became the new Headquarters for the ICDD. J. Messick retired in 1994 and Dan Richardson was employed as Secretary and General Manager. In 1996, R.L. Snyder was elected Chairman of the ICDD and R. Jenkins was appointed Secretary and Executive Director. Over the intervening years, John Faber joined the Headquarters staff as Principal Scientist as the ICDD made remarkable progress in database management and product development. C.R. Hubbard served as Chairman of the ICDD from 2000 to 2004 and James A. Kaduk from 2004 to 2008. In 2009, Tom Blanton became Chairman of the ICDD. As chairmen, they all played a major role in the advances of the ICDD. As a group of chairmen and scientists, they were all personally involved in the generation and evaluation of computer-enhanced analyses of powder diffraction data. During this period, the concept of “Total Pattern Analysis” was put forward in many presentations by the chairmen, where all aspects of diffraction and scattering can be extracted from the patterns of materials (Hubbard, 2000, 2001). The scope of the ICDD was expanded beyond crystalline materials to all materials. The 1990s began a period of international collaborations as the PDF grew with the additions of powder patterns and physical property data calculated from single-crystal crystallographic experiments. Between 1998 and 2001, the ICDD negotiated data access agreements with Fachinformationszentrum Karlsruhe (FIZ), the Cambridge Crystallographic Data Centre (CCDC), and the National Institute of Standards and Technology (NIST). In 2003, the ICDD negotiated a collaboration agreement with the Material Phases Data System. The PDF was modified to include the use of powder patterns and physical property data calculated from single-crystal diffraction data (using the POWD program developed by D.K. Smith). A tremendous amount of editorial effort went into standardizing the formats from the different database 43

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organizations, categorizing the data and reviewing the quality of the data, independent of whether it came from a powder diffraction or single-crystal experiment. The fundamental structure of the database was changed to accommodate the large increase in data as the database was put into a relational database housing. Today, the PDF includes 750,000 material data sets published in several database products. The PDF is growing rapidly as over 50,000 new data sets are processed each year. The workshops and tutorials started in the 1980s have now expanded to a global network of workshops, clinics, and symposia that are sponsored by the ICDD and include many ICDD members and staff as instructors. ACKNOWLEDGMENTS

Special thanks to Terry Kahmer, Terry Maguire, and Donna Barry for their assistance in gathering information. Tim Fawcett and Gerald Johnson also contributed content and references. Blanton, T. N. (2003). “X-ray Film as a two dimensional detector for x-ray diffraction analysis,” Powder Diffr. 18(2), 91–98. Davey, W. P. (1941). “Foreword” to the card file of X-ray diffraction data, Set 1, cards 1–6. Davey, W. P. (1944). “Foreword” to the First Supplement card file, Supplement Set, cards 1–5 (ASTM, Philadelphia, PA, USA). In later years, this First Supplement later became Set 2 of the Powder Diffraction File. Davey, W. P. (1945). Alphabetical Index of X-ray Patterns, Covering the First Supplementary Set of Cards (ASTM, Philadelphia, PA, USA). Davey, W. P. (1952). Alphabetical and Grouped Numerical Index of X-Ray Diffraction Data (ASTM, Philadelphia, PA, USA). Davey, W. P., Hochgesang, F. P., Stevens, M., and Reed, J. B. (1942). Alphabetical Index of X-ray Diffraction Patterns (ASTM, Philadelphia, PA, USA). This index contained both alphabetical names and formula cross-referenced to cards and the strongest line in the diffraction pattern. Frevel, L. K. (1965). “Computational aids for identifying crystalline phases by powder diffraction,” Anal. Chem. 37(4), 471–482. Frevel, L. K., Adams, C. E. and Ruhberg, L. R. (1976). “A fast search-match program for powder diffraction analysis,” J. Appl. Crystallogr. 9, 199–204. Hanawalt, J. D. (1986). “Manual search/match methods for powder diffraction in 1986,” Powder Diffr. 1, 7–13. 17. Hanawalt, J. D. and Rinn, H. W. (1986). “Identification of crystalline materials,” Powder Diffr. 1, 2–6. This is a reprint of the original article written in Industrial and Engineering Chemistry, Analytical Edition (1938), 10, 820–830. Hanawalt, J. D., Rinn, H. W., and Frevel, L. K. (1938). “Chemical analysis by X-ray diffraction,” Ind. Eng. Chem. Anal. Edn 10(9), 457–512. Hubbard, C. R. (2000). “ICDD Reinvented,”; presented at the ICDD Workshop at EPDIC-7, Barcelona, Spain. Hubbard, C. R. (2001). “NIST/ICDD powder diffraction research: a continuing collaboration for nearly 50 years,” presented at the NIST Centennial Celebration Symposium, American Crystallographic Association, Los Angeles, CA, USA. Hull, A. W. (1919). “A New Method of Chemical Analysis,” J. Am. Chem. Soc. 41(8), 1168–1175. PDF (or X-ray Diffraction Card Files) (1941) (ASTM, Philadelphia, PA, USA). The first six cards in each card file contains a short history of the file, the associated organizations of the Joint Committee on Chemical Analysis by X-ray Diffraction Methods, members of the Joint Committee and their affiliations. The original records are kept in the historical archives of the ICDD. For several years after publication of the first card set in 1941, the cards were referred to as “The Cards for the Identification of Crystalline Materials by the Hanawalt X-ray Diffraction Method”. Jenkins, R. and Smith, D. K. (1996). “The powder diffraction file: past present and future,” J. Res. Natl. Inst. Stand. Technol. 101, 3–20. Available online at http://www.icdd.com/products/ICDD.PDF Johnson, G. G. and Vand, V. (1967), “A computerized powder diffraction identification system,” Ind. Eng. Chem. 59(8), 19–31. The history of the International Centre for Diffraction Data

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Kabekkodu, S. (2011). “The Powder Diffraction File, PDF-4 + ,” Release 2011 published by the ICDD. Maguire, T. (2010). Private communication, “The Denver X-Ray Conference,” T. Maguire is Manager of Conference Services as well as Corporate Secretary of the ICDD. Mighell, A., Gasper, P., and Wong-Ng, W. (2004). “An appreciation, Howard McMurdie remembrance” http://www.icdd.com/profile/whatsnew/ mcmurdie-2.htm Nichols, M. C. (1966). “A Fortran II program for the identification of X-ray powder patterns,” UCRL-70078, Lawrence Livermore Laboratory.

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Smith, D. K. (1986). “Editor’s note and introduction to chemical analysis in X-ray diffraction,” 2, 1. Swanson, H. E. and Tatge, E. (1953), “Standard X-ray diffraction powder patterns”, United States Department of Commerce, National Bureau of Standards, Circular 539 (1). This National Bureau of Standards Monograph series was published from 1953 until 1985. Later versions were printed under Monograph 25 with successive sections published in each monograph. Numerous editors and research scientists contributed to the monograph series. Wyman, L. L. (1966–1975). Thesis, JCPDS/ICDD 1966–1975.

Messick

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INTERNATIONAL REPORT ICDD PDF-4 Workshop T. N. Guru Row Indian Institute of Science, Bangalore, India [email protected]

The ICDD PDF-4 Workshop was held on June 26, 2011 as a pre-conference meeting of the 20th International Conference on the Chemistry of the Organic Solid State (ICCOSS XX), June 25–30, 2011. The conference was organized by the Solid State and Structural Chemistry Unit of the Indian Institute of Science (IISc), Bangalore, India. The details of the workshop are as follows: Title: Date: Time: Venue:

ICDD PDF-4 June 26, 2011 9:00 a.m. to 4:00 p.m. Faculty Hall, IISc, Bangalore

Lead Instructor: Soorya Kabekkodu, International Centre for Diffraction Data (ICDD), USA (Figure 1). Assisted by: T. N. Guru Row, IISc, India, Graciela Delgado, Universidad de los Andes, Venezuela (Figure 2). The Power Diffraction File (PDF) contains over 700 000 entries in two major databases. Release 2010 PDF-4+ contains predominately inorganic materials and has 301 282 material data sets and PDF-4/Organics contains organic and pharmaceutical materials and has 436 901 material data sets. This workshop demonstrated the extensive data mining potential of the PDF-4+ database using the powerful search capabilities of DDview and worked examples. The database itself can be data mined to provide insights into the materials state of matter, crystallinity, solid solution behavior, polymorph composition, and multiphase composition.

Figure 1. (Color online) Soorya Kabekkodu (lead instructor) and workshop attendees at the ICDD PDF-4 Workshop at the Indian Institute of Science, Bangalore.

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Figure 2. (Color online) Graciela Delgado lecturing at the ICDD PDF-4 Workshop at the Indian Institute of Science, Bangalore.

The following topics were covered at the workshop: • • • •

Selecting search criteria for up to 53 unique search fields. Viewing/analyzing search results. Using history and standard formats to optimize searches. Using digital patterns for data simulations and analysis.

The workshop started with brief introductory remarks by Prof. Guru Row and an example from his personal research, followed by Dr. Soorya Kebbakodu and Prof. Graciela Delgado who covered the above topics throughout the day with hands on training, winding up with a technical discussion involving the participants. The workshop also emphasized the use of the database for phase identification with SIEVE+ software and a range of examples to allow participants to work on materials of particular interest to them. Some registered participants brought their laptop computers to make the best use of the hands-on session and problem-solving discussions. The participants were from various educational institutions, and also included representatives from R&D associated with the pharmaceutical and cement industries from different parts of India. Several participants were also registrants of the main meeting. This is the first such training program on ICDD PDF-4 offered in India, and the participants benefitted greatly.

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INTERNATIONAL REPORT International Union of Crystallography (IUCr) XXII Congress, Madrid, August 22–30, 2011 James A. Kaduk Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, Illinois 60616 [email protected]

This report is necessarily highly idiosyncratic. With at least seven simultaneous sessions going on throughout the International Union of Crystallography (IUCr) XXII Congress, Madrid, August 22–30, 2011, any one person could not hope to cover them all—even for a subset such as materials crystallography. In microsymposium MS05, “Non-Ambient Powder Diffraction,” Robert Dinnebier (Max Planck Institute for Solid State Research, Stuttgart, Germany) described new tools for the analysis of in situ XRD data, including symmetry mode analysis, parametric Rietveld refinements, and maximum entropy methods. Many of these facilities are incorporated in the Powder3D suite of programs (http://www.fkf. mpg.de/xray/html/powder3D.html). MS10 concerned determination of ab initio crystal structures from powder diffraction and their applications in the pharmaceutical industry. Chris Gilmore (University of Glasgow, UK) incorporated the maximum entropy software MICE into the Superflip charge flipping program, combining two powerful structure solution algorithms into one package. In MS18, “Powder Diffraction at the Nanoscale,” a number of leading workers presented new results on total X-ray diffraction analysis, including pair distribution functions and Debye functions. This theme continued in MS26, “Total Scattering and the Nanostructure Problem.” Much powder diffraction is conducted in industry, and the results are proprietary. In MS32, “Crystallography in Industrial Process Control,” five speakers were willing to share industrially relevant results. Nikki Scarlett’s colleague X-ray Ted (CSIRO, Australia) made a special guest appearance (see Figure 1). Jürgen Niebauer (University of

Figure 1. (Color online) X-ray Ted making a special guest appearance at the 2011 Conference of the International Union of Crystallography (IUCr) XXII Congress. 46

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Erlangen-Nuremberg, Erlangen, Germany) discussed the tricky problem of quantifying the amorphous content of ordinary Portland cement. He obtained an absolute calibration by using an external standard, and determined the linear absorption coefficient of the mixture from the bulk X-ray fluorescence analysis. Dan Riley (University of Newcastle, New South Wales, Australia) applied time-resolved neutron diffraction to study titanium silicon carbides. Neutron diffraction was necessary to determine the bulk compositions, not just the surface compositions derived using X-rays. Riley found that a short-lived (∼3 s) face-centered cubic intermediate occurs at ∼2600 °C. Ping Liu (Sandvik AB, Sandviken, Sweden) characterized the residual stresses in spring steels. Grazing incidence techniques were used to profile the strong gradients, and electrochemical polishing enabled characterization of the depth profiles. Bob Cernik (University of Manchester, Manchester, U.K.) described the development of rapid tomographic energy-dispersive diffraction imaging using a small incident beam. To obtain results in reasonable times, detector arrays are necessary. Constanza Buioli (Atomic Energy Commission, Argentina) characterized Zr alloy reactor tubes by studying cut sections. Other sessions containing information useful to readers of Powder Diffraction included (MS04) “Industrial Applications of SAXS and SANS,” (MS14) “Biomineralization and Biomimetic Materials,” (MS19) “Synthesis, Structure, and Properties of Novel Materials at High Pressure,” (MS25) “Crystallography of Materials with Exchange, Sequestration, and Storage Properties,” (MS31) “Structural Implications in Catalytic Processes,” (MS39) “Energy-Related Materials,” (MS40) “Pressure-Induced Phase Transitions,” (MS46) “Powder Diffraction Methods in Archaeometry,” (MS54) “Minerals as Advanced Materials,” (MS60) “Solid State Reactivity,” (MS74) “Powder Diffraction and Complementary Techniques,” and (MS81) “The Crystallography of Functional Inorganic Materials and Their Applications.” MS95, “Automated Data Processing and Structural Solution for Powder Crystallography,” included a talk by Angela Altomare (University of Bari, Italy) on new features in EXPO2011. These include Rietveld refinement in addition to structure solution capabilities. In MS83, “Application of Crystal Structure Information in Chemical Education,” the web-based educational materials developed by Dean Johnson (Otterbein University, Westerville, Ohio) were particularly impressive. In MS97, “Web-Based Crystallography Teaching: the Use of Modern Communication Methods to Teach Crystallography,” Anders Markvardsen (ISIS Facility, Rutherford Appleton Laboratory, UK) described Jpowder, a Java program for the display of powder diffraction information.

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Among the three Ewald Prize lectures, Carmelo Giacovazzo’s (University of Bari, Italy) was particularly interesting, as he discussed the consequences of considering the variances of electron density maps. Gautam Desiraju (new IUCr President) gave a wonderful plenary lecture entitled “Crystal Engineering: From Molecules to Crystals,” and coined the term “molecular sociology” to describe crystal engineering. The Commission on Powder Diffraction (CPD) decided to make a number of important Acta Crystallographica papers open access. These include the guidelines for Rietveld refinement and the two papers on the CPD Round Robin on Quantitative Phase Analysis. An exceptionally large amount of behind-the-scenes activity goes on at an IUCr meeting. For the readers of

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Powder Diffraction, an important development was that Chris Gilmore, Jim Kaduk (Illinois Institute of Technology, Elgin, IL), and Henk Schenk (University of Amsterdam, Netherlands) agreed to serve as editors of a new Volume H of the International Tables for Crystallography devoted to powder diffraction. Selection of chapter authors and development of the outlines are underway. In addition to the usual fundamental material, Volume H will contain a number of special topic chapters on the applications of powder diffraction to specific fields. These chapters are intended to be useful for both the beginner and the expert practitioner. These chapters will include test data with suggestions for data processing. Volume H will be the first International Tables volume for which the electronic version should be considered the primary publication, though there will continue to be a print volume.

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INTERNATIONAL REPORT XX International Materials Research Conference José Miguel Delgado Universidad de Los Andes, Venezuela [email protected]

The XX International Materials Research Conference (IMRC-XX) was held at the CasaMagna and J.W. Marriott Hotels in Cancun, Mexico, from August 14 to 19, 2011. This meeting was successfully organized by the Sociedad Mexicana de Materiales (SMM) and the Materials Research Society (MRS), and has become a popular materials research conference. More than 1500 scientists attended this meeting (Figure 1). The plenary speakers were Prof. Eduard Arzt (Leibniz Institute for New Materials, Saarbrücken, and Saarland University, Germany), Prof. Ivan Schuller (University of California-San Diego, U.S.A.), Prof. Sumio Iijima (Meijo University, Tenpaken, Nagoya, Japan), and Prof. Dan Shechtman (Technion, Israel). It is noteworthy that Prof. Shechtman received the 2011 Nobel Prize in

Figure 1. 48

Chemistry a few months later. In his plenary talk “Quasi-periodic materials: crystal redefined,” Prof. Shechtman described the process of changing the paradigm of the structure of crystals, and the debate between believers and non-believers in his discovery of the icosahedral phase. Six tutorial courses on Photovoltaics and Solar Energy Materials, Biomaterials for Tissue Engineering, Nanomaterials applied in Energy Storage Devices, and other interesting topics were conducted on Sunday, August 14, 2011. Twenty-three symposia, evening poster sessions, a science luncheon, and commercial exhibitions filled the following days. Despite the full schedule, attendants managed to find opportunities to relax and enjoy the wonderful beaches and other facilities that the conference venue offered, and go

(Color online) Scenes from XX International Materials Research Conference. Powder Diffraction 27 (1), March 2012

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on excursions to interesting sites nearby. The Mayan archeological sites of Chichén-Itzá and Tulum and the theme parks Xcaret and Xel-Há were among the favorites. Following participation in IMRC-XIX with a Workshop on the “ICDD Databases and Programs,” the International Centre for Diffraction Data (ICDD) sponsored and participated this time in the Workshop on “Crystal Structure/ Properties and Phase Identification using X-ray Powder Diffraction Techniques,” co-organized by the SMM and the Sociedad Mexicana de Cristalografía (SMCr). José Álvaro Chávez-Carvayar, Lauro Bucio-Galindo, and María Elena Villafuerte-Castrejón (Faculty members of Universidad Nacional Autónoma de México—UNAM, Mexico) organized this workshop, with Prof. Kenneth R. Poeppelmeier (Chemistry Department, Northwestern University, U.S.A.) as an invited speaker. Miguel Ángel Alario y Franco (Universidad Complutense de Madrid, Spain) talked about “Structure, defects and properties of non-molecular solids.” Lauro Bucio (UNAM, Mexico) discussed “High-quality

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X-ray powder diffraction data collection.” Miguel Delgado (Universidad de los Andes—ULA, Mérida, Venezuela) presented the lecture “The International Centre for Diffraction Data and its Powder Diffraction File.” Dr. Cyrus Crowder (ICDD) gave a great overview of “Phase identification using X-ray powder diffraction techniques and the use of PDF-4+ for data mining.” Some of the most important manufacturers of equipment used in the characterization of materials participated in the commercial exhibition. Helen McDonnell and Cyrus Crowder (ICDD), with some help from Prof. Graciela Díaz de Delgado (ULA, Mérida, Venezuela), were at the ICDD booth answering questions about ICDD, its databases, academic programs, and other related activities. The use of PDF-4+ was demonstrated during the workshop and in the booth. IMRC-XXI will take place from August 13 to 17, 2012 at the same venue. Meeting information will be available at http://www.mrs.org/imrc2012/.

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INTERNATIONAL REPORT The Materials Science & Technology 2011 Conference & Exhibition Winnie Wong-Ng Ceramics Division, NIST, Gaithersburg, Maryland 20899 [email protected]

The Materials Science & Technology (MS&T) 2011 Conference & Exhibition took place at the Greater Columbus Convention Center in Columbus, Ohio from October 16 to 20, 2011. The city, named after explorer Christopher Columbus, was founded in 1812 at the confluence of the Scioto and Olentangv rivers, and assumed the functions of state capital in 1816. Modern Columbus has emerged as a technologically sophisticated city. It is home to the world’s largest private research and development foundation, the Battelle Memorial Institute and Chemical Abstracts Service, and to the nation’s largest campus, the Ohio State University. The Greater Columbus Convention Center is a state-of-the-art facility conveniently located in downtown Columbus. It features 410 000 square feet of exhibition space, 3 ballrooms, and 65 meeting rooms. The attendees enjoyed the spacious and state-of-the-art convention center as well as the amenities throughout the week. The meeting committee of the MS&T 2011 Conference included the chair David K. Matlock (Colorado School of Mines, Golden, Colorado), and members George G. Wicks (Savannah River National Laboratory, Savannah River Site, South Carolina), Christopher Berndt (Swinburne University of Technology, Australia), and Kevin Hemker (Johns Hopkins University, Baltimore, Maryland). The conference was successfully organized, with a total of more than 3200 attendees. The meeting committee did an admirable job of assembling the rich scientific program, the large-scale exhibition, and enjoyable social programs. The MS&T 2011 Conference was the leading forum addressing structure, properties, processing, and performance across the materials community. The conference featured the 113th Annual Meeting of the American Ceramic Society (ACerS), the Steel Properties & Applications Conference of the Association for Iron and Steel Technology (AIST), the 98th Annual Meeting of the American Society for Metals (ASM), the Fall Meeting of The Minerals Metals and Materials Society (TMS), and NACE International (previously the National Association of Corrosion Engineers). These organizing societies provided the MS&T 2011 Conference with 71 symposia organized into 11 themes: (1) Biomaterials (3 symposia), (2) Ceramics and Glass Materials (9 symposia), (3) Electronic and Magnetic Materials (5 symposia), (4) Environmental and Energy Issues (5 symposia), (5) Fundamental and Characterization (12 symposia), (6) Iron and Steel (4 symposia), (7) Materials Performance (9 symposia), (8) Materials–Environment Interactions (5 symposia), (9) Nanotechnology (4 symposia), (10) Processing and Product Manufacturing (10 symposia), and (11) Special Topics (5 topics). Over 2000 presentations covered both parallel oral sessions and poster presentations. The conference plenary session, entitled “Grasping excellence: opportunities for science and engineering research, 50

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education and workforce development in the United States,” took place on Monday, October 17, 2011. Four prominent speakers from the U.S. Government and Industries gave their expert views on the following topics: “Innovation ecosystems: where do we go from here?” (Subra Suresh, Director of U.S. National Science Foundation), “Taking a scientific approach to learning and teaching STEM” (Carl E. Wieman, Associate Director for Science, Office of Science and Technology Policy, the White House), “Responding to increasing energy, environmental, health and national security challenges—investment, policy and talent issues” (Jeffrey Wadsworth, President and CEO of Battelle Memorial Institute), and “Challenges in aerospace and defense” (Alton D. Romig, Jr., Vice President and General Manager of Advanced Development Program, The Skunk Works, Lockheed Martin Aeronautics). A number of memorable plenary talks took place at the meeting. The ACerS lectures included the Frontiers of Science and Society—Rustum Roy Lecture “Reinventing manufacturing to answer new global challenges and market opportunity” by Deborah Wince-Smith (President and CEO of the Council on Competitiveness), the ACerS/NICE Arthur L. Friedberg Memorial Lecture “Processing dielectric oxides-new opportunities and challenges” by Clive A. Randall (Pennsylvania State University, University Park, Pennsylvania), the Eward Orton Jr. Memorial Lecture “Lessons learned after 40 years of sintering technical ceramics” by Gary L. Messing (Pennsylvania State University), and Basic Science Division’s Robert B. Sosman Award and Lecture “Interface-structure dependent microstructural evolution in ceramics” by Suk-Joong L. Kang (Korea Advanced Institute of Science and Technology). Seven short courses were offered during the meeting. These courses included: “Modern Statistics, Data Analysis, and Specimen/Structural Reliability Modeling” (Jeffrey Fong and Stephen W. Freiman), “Achieving your goal through effective communication” (Larry Wagner), “Materials Enabled Design” (Michael Pfeifer), “Microstructures 101 and Beyond” (Frauke Hogue), “Fundamental of Glass Science and Technology, Fractography Lab” (Arun. K. Varshneya), “Sintering of Ceramics” (Mohamed N. Rahaman), and “Thermal Spray Technologies” (Christopher Berndt). A series of student activities were also scheduled to ensure that young people have opportunities to learn leadership skills, to learn about career development, to mingle with other wellestablished scientists and with each other, and to be recognized among their peers. These activities included student speaking contest, student service project, undergraduate student poster contest, student networking mixer, AIST student plant tour, AIST Foundation Student Recruiting Reception, ACerS PCSA student tour of Owens Corning Science and Technology Center, as well as Material Advantage putting

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Figure 1.

(Color online) Scott Misture at the International Centre for Diffraction Data (ICDD) booth at the MS&T 2011 Conference.

contests, Material Advantage mug drop contest, student career connection, and student awards ceremony. The large-scale exhibition is an important part of the MS&T Conference that compliments the scientific program. At the MS&T 2011 Conference, more than 120 international exhibitors displayed their latest products and services. Exhibitors included analytical equipment manufacturers, materials producers, book and journal publishers, database and software producers, scientific societies, scientific consultants, and sponsoring companies. The International Centre for Diffraction Data (ICDD) also had an exhibit booth featuring the latest PDF products and services (Figure 1). The exhibition hall was a popular place to meet old friends and colleagues and to meet new people. The poster session also took place at the exhibition hall. Other conference events included the welcome reception, the ACerS Annual Membership Meeting, the ACerS Honors and Awards Banquet and Afterglow, ASM Reception, ASM

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Leadership Luncheon, ASM Awards Dinner, ASM President’s Reception, Women in Materials Science and Engineering Reception, MS&T Plenary Speaker Reception, AIST Foundation University–Industry Relations Roundtable, and ACTA Materialia Luncheon. There were refreshment breaks during the morning and afternoon technical sessions throughout the week. The exhibitors also held a happy hour reception. Member lounges were also available for ACerS, AIST, ASM, and TMS societies in the Convention Center. Each morning coffee was available for authors and session chairs of the program of the day. Various universities, including Alfred University, Purdue University, Drexel University, Michigan Technological University, Pennsylvania State University, University of Illinois, and North Carolina State University, also held alumni receptions. The attendees are invited to attend the MS&T 2012 Conference and Exhibition to be held in Pittsburgh, Pennsylvania, from October 7 to 11 2012.

The Materials Science & Technology 2011 Conference & Exhibition

51

CALENDAR Calendar of Forthcoming Meetings Gang Wang Research and Development Center for Functional Crystals, Institute of Physics, Chinese Academy of Sciences, No. 8 Nansanjie, Zhongguancun, Haidian District, Beijing 100190, China [email protected]

26–29 April 2012 Second International Advances in Applied Physics and Materials Science Congress WOW Kremlin Palace, Antalya, Turkey [Info: http://www.apmas2012.org/447-main-page.aspx] 16–24 June 2012 Seventh International Topical Meeting on Neutron Radiography (ITMNR-7)-Applications and Imaging for Neutron Radiology and Tomography Confederation Place Hotel, Kingston, Ontario, Canada [Info: http://itmnr-7.com/] 17–20 June 2012 European Conference on Crystal Growth 2012 (ECCG4) University of Strathclyde, Glasgow, Scotland, United Kingdom [Info: http://eccg4.org/] 18–22 June 2012 European Conference on X-Ray Spectrometry (EXRS 2012) Vienna, Austria [Info: http://www.ati.ac.at/ EXRS2012/index.html] 24–28 June 2012 2012 American Conference on Neutron Scattering (ACNS 2012) Georgetown University Hotel and Conference Center, Washington, District of Columbia, U.S.A. [Info: http://www. mrs.org/acns-2012/] 1–6 July 2012 International Conference of Young Researchers on Advanced Materials (ICYRAM 2012) Singapore [Info: http://www.mrs.org.sg/icyram2012/home.htm]

Boston, Massachusetts, U.S.A. [Info: http://www.amercrystalassn.org/2012-meeting-homepage] 4–6 August 2012 Magnetic Symmetry and its Applications (MaThCryst Satellite Conference) University of Bergen, Bergen, Norway [Info: http://www.crystallography.fr/mathcryst/bergen2012.php] 5–10 August 2012 Eleventh International Conference on X-ray Microscopy (XRM2012) Shanghai, China [Info: http://www.sinap.ac.cn/ xrm2012/] 6–10 August 2012 2012 Denver X-ray Conference (DXC 2012) Denver Tech Center Hotel, Denver, Colorado, U.S.A. [Info: http://www. dxcicdd.com/12/index.htm] 7–11 August 2012 The 27th Meeting of the European Crystallographic Association (ECM27) Bergen, Norway [Info: http://ecm27. ecanews.org/] 13–17 August 2012 XXI International Materials Research Congress (IMRC 2012) Cancun, Mexico [Info: http://www.mrs.org/imrc2012/] 2–6 September 2012 The First European Mineralogical Conference (EMC2012) Johann Wolfgang Goethe University, Frankfurt, Germany [Info: http://emc2012.uni-frankfurt.de/]

15–19 July 2012 Fourth International Congress on Ceramics (ICC4) Sheraton Chicago Hotel and Towers, Chicago, Illinois, U.S. A. [Info: http://ceramics.org/4th-international-congress-on-ceramics-icc4/]

2–6 September, 2012 The XXII Conference on Applied Crystallography Targanice/Andrychów, Poland [Info: http://www.cac.us.edu.pl/]

22–28 July 2012 The 15th International Conference on X-ray Absorption Fine Structure (XAFS15) Beijing, China [Info: http://www. xafs15.org/index.asp]

2–6 September 2012 Ninth European Conference on Silicon Carbide and Related Materials (ECSCRM 2012) Saint-Petersburg, Russia [Info: http://www.ecscrm-2012.org/]

27–31 July 2012 The 11th Chinese National Conference on X-ray Diffraction and ICDD Workshop Changchun, Jilin, China [More information forthcoming soon]

15–20 September 2012 The 11th Biennial Conference on High Resolution X-Ray Diffraction and Imaging (XTOP 2012) St. Petersburg, Russia [Info: http://xtop12.org/]

28 July–1 August 2012 2012 Meeting of the American Crystallographic Association (ACA 2012) Westin Boston Waterfront Hotel,

18–23 November 2012 SAS2012 International Small-Angle Scattering Conference Sydney, Australia [Info: http://www.sas2012.com/]

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18–23 November 2102 XIII Latin American Seminar of Analysis by X-Ray Techniques (SARX 2012) Santa Marta, Colombia [Info: http://difraccionderayosx.uis.edu.co/] 11–16 August 2013 Seventeenth International Conference on Crystal Growth

and Epitaxy (ICCGE-17) Warsaw, Poland [Info: http:// science24.com/event/iccge17/]. 25–29 August 2013 The 28th Meeting of the European Crystallographic Association (ECM28) University of Warwick, Warwick, United Kingdom [Info: http://ecm28.org/]

****** (All information above as of 12 January, 2012) ******

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Calendar of Forthcoming Meetings

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Short Courses & Workshops 9–13 April 2012 School on Fundamental Crystallography Mahdia, Tunisia [Info: http://www.crystallography.fr/mathcryst/mahdia2012.php]

Pharmaceutical Solids (IWPCPS-14) Technical University of Barcelona, Barcelona, Spain [Info: http://www.iucr.org/ news/notices/meetings/meeting_2011_252]

30 April–4 May 2012 Practical X-ray Fluorescence Clinic ICDD Headquarters, Newtown Square, Pennsylvania, U.S.A. [Info: http://www. icdd.com/education/xrf.htm]

2–5 July 2012 Ninth International Workshop on Polarised Neutrons in Condensed Matter Investigations The Jean Monet center, Paris, France [Info: http://iramis.cea.fr/meetings/ 2012PNCMI/index.php]

31 May–10 June 2012 Present and Future Methods for Biomolecular Crystallography The 45th crystallographic course at Ettore Majorana Centre, Erice, Italy [Info: http://www.crystalerice. org/Erice2012/2012.htm]

4–6 July 2012 Fourth International Workshop on Metrology for X-ray Optics, Mirror Design, and Fabrication Barcelona, Spain [Info: http://iwxm.cells.es/]

4–8 June 2012 Fundamentals of X-ray Powder Diffraction ICDD Headquarters, Newtown Square, Pennsylvania, U.S.A. [Info: http://www.icdd.com/education/xrd.htm]

19–23 July 2012 Insubria International Summer School: Crystallography for Health and Biosciences Como, Italy [Info: http://scienzecomo.uninsubria.it/iiss2012/IISS2012.htm]

7–14 June 2012 11th European School on “Scattering Methods Applied to Soft Condensed Matter” Gironde, France [Info: http:// www.ill.eu/en/html/news-events/events/bombannes-2012/]

12–25 August 2012 National School on Neutron and X-ray Scattering Argonne National Laboratory, Argonne, Illinois and Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. [Info: http://www.dep.anl.gov/nx/]

11–15 June 2012 Advanced Methods in X-ray Powder Diffraction ICDD Headquarters, Newtown Square, Pennsylvania, U.S.A. [Info: http://www.icdd.com/education/xrd.htm]

25 November–3 December 2012 International School on Fundamental Crystallography Uberlândia, Brazil [Info: http://www.crystallography.fr/mathcryst/uberlandia2012.php]

25–28 June 2012 International Workshop on Physical Characterization of

****** (All information above as of 12 January, 2012) ******

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Powder Diffraction notes for authors I. SCOPE Powder Diffraction is a quarterly journal publishing articles, both experimental and theoretical, on the use of powder diffraction and related techniques for the characterization of crystalline materials. It is published by Cambridge University Press (CUP) for the International Centre for Diffraction Data (ICDD). II. CATEGORIES OF MANUSCRIPTS Publications in Powder Diffraction should fall under one of the following categories: (1) Review Articles may be voluntary or solicited and are intended to be an authoritative presentation of a significant subject in powder diffraction analysis. The material should be comprehensive, and the historical influence on the topic should be emphasized along with modern enhancements. A complete literature search is an important part of review articles. (2) Technical Articles on original research may be either experimental or theoretical studies revealing new information on the applications of powder diffraction and related techniques for the characterization of materials. Topics may include, but are not limited to, qualitative and quantitative phase analysis, characterization of new materials, characterization of thin films, diffraction measurements coupled with computer analyses, instrumental techniques, assessment of precision and accuracy in data processing, indexing of powder data, crystal-structure determination or refinement of powder data, residual stress analysis, and microstructural measurements such as those for preferred orientation, crystallite size, microstrain and microstructure defects. (3) New Diffraction Data are short articles which present powder diffraction patterns and associated experimental documentation on crystalline materials of interest to science and industry. The scientific and materials significance of the compounds should be described, and the documentation should follow the guidelines presented in section V (Manuscript Preparation) below. (4) Rapid Communications are short articles on original research, usually limited to two printed pages of about 1000 words. They may include the same topics as in section (2), but are designed for rapid processing and publication. These may also include descriptions of new computer programs. (5) Laboratory Notes are short articles on new techniques of diffraction analysis or modifications of equipment implemented in specific laboratories or for specific materials. They are usually limited to two printed pages of about 1000 words. (6) Crystallography Education provides tutorial and instructional articles related to powder diffraction crystallography. The creation of educational materials about crystallography not found in books or manuals is encouraged. This section will publish invited and contributed articles, and will be subjected to the normal editing process before publication. (7) Letters to the Editor is a forum for individuals to discuss material printed in Powder Diffraction. A letter will be reviewed by the editor-in-chief, who will suggest changes in presentation, if appropriate. A letter that refers to a specific publication will be sent to the author(s) of the article under discussion for a reply. Usually, the letter and the reply (if available) will appear in the same issue. (8) Erratum is a forum to be used by the author to submit corrections to published papers in Powder Diffraction. 55

(9) International Reports is a section of Powder Diffraction devoted to disseminating current information on activities of interest to the powder diffraction community. Submissions are solicited from anyone with appropriate information. Topics of interest include announcements, reviews of meetings, book reviews, educational activities, people working in the field of powder diffraction, especially their awards and honors, activities of any organization worldwide which pertain to powder diffraction, and very short descriptions of new products. (10) Calendar of Meetings and short Courses and Workshops is a section listing meetings and workshops of interest to the powder diffraction community. Please do not use ScholarOne to submit a calendar notice. Please send notices by e-mail to the Calendar of Meetings and Workshops Editor (gangwang@ aphy.iphy.ac.cn).

III. SUBMISSION OF MANUSCRIPTS All manuscripts must be submitted to ScholarOne online at http://mc.manuscriptcentral.com/pdj. This web-based manuscript submission and peer review system is hosted by Thomson Reuters on behalf of Cambridge University Press. ScholarOne is an editorial management service that provides electronic processing of manuscripts from author submission to manuscript review, revision, and final approval. Review the online submission guidelines and tutorials available at http://mchelp.manuscriptcentral. com/gethelpnow/training/author/before submitting your paper. Additional assistance is available from http://mc.manuscriptcentral.com/pdj under “Resources” in red at the top right corner of the screen. Submission of a manuscript is considered an implicit guarantee that the paper has not been published previously in any language or concurrently submitted for publication to another journal. You will be asked to confirm this during submission. If accepted for publication in Powder Diffraction, a signed publishing agreement transferring full-term copyright to ICDD will be required. The copyright form is located at http://www.icdd.com/resources/pdj/authors.htm. You may mail, fax, or e-mail the signed agreement to the attention of the managing editor at: Nicole M. Ernst Boris Managing Editor, Powder Diffraction 12 Campus Blvd. Newtown Square, PA 19073 Phone: 610-325-9814 Fax: 610-325-9823 E-mail: [email protected]

IV. REVIEW OF SUBMISSIONS Acceptance of manuscripts for publication is the responsibility of the editor-in-chief. Manuscripts are usually reviewed by two qualified individuals selected by an assigned editor. Referees will be asked to certify the appropriateness of the subject matter for Powder Diffraction and to comment on the technical merit and presentation of the article. Authors, not reviewers, are responsible for preparing the manuscript in readable English. Manuscripts too difficult to read will be returned to the authors without review. The review process will be conducted anonymously unless a reviewer specifically instructs the editor to reveal his or her identity. Authors may request anonymity by selecting the appropriate option during submission and by preparing the manuscript so that the file and the paper itself do not identify the author(s). Authors may also suggest a specific individual to act as reviewer or indicate an individual who they do not want to review the paper. The author submitting the manuscript will be considered the corresponding author. 56

The review process will result either in acceptance of the manuscript, suggested modifications of the text prior to acceptance, or rejection of the manuscript. In cases where reviewers differ significantly in their evaluation of a paper, the editor may request a third review. When changes are required, the manuscript will be returned to the corresponding author for revision. If manuscripts returned to the author are not resubmitted within a reasonable time, the manuscript will be considered withdrawn, and a subsequent submission will be treated as a new article. All changes should be accompanied by a separate document/file detailing the responses to the reviewer’s recommendations. Manuscripts which require major changes may be sent to the reviewers for their acceptance of the changes. When the assigned editor feels the paper is ready for publication, he or she will send the paper to the editor-in-chief for a final decision on publication. When the manuscript has been accepted for publication in Powder Diffraction, the author will be informed, and the manuscript will be passed on to the publisher. Rejected manuscripts will be returned to the author with comments and reasons for rejection. Processing dates published with the manuscript will include the date the manuscript was submitted (received date) and the date of acceptance by the editor-in-chief (accepted date). The date of acceptance may be delayed until all requested revisions, figures, or other parts of the paper are received. V. MANUSCRIPT PREPARATION For categories (1) to (6) manuscripts, follow these manuscript preparation instructions. Manuscripts must be written in English and will be published in English. Authors are expected to follow conventional writing, notation, and illustration style as prescribed in these notes. It is suggested that authors also examine the style of the appropriate article type as presented in a recent issue of Powder Diffraction and the CUP style guide located at: www.cambridge.org/us/notesforauthors/cambridge_style.doc. Abbreviations, symbols, and units should correspond with suggestions in these notes and examples of previous articles. It is strongly suggested that authors have a co-author or colleague not primarly responsible for the writing to review the manuscript before submission. A. Text of paper 1. Abstract

An abstract must accompany all articles. The abstract should be double-spaced on the first page, separate from the rest of the manuscript. An abstract is a self-contained, brief summary of a paper. It is used to communicate complex research and findings efficiently. Because online search databases contain abstracts only, it is vital to write a complete, but concise, description of your work to encourage others into obtaining a copy of the full paper. The decision to read the entire paper is often predicated on what the reader finds in the abstract. An abstract is the most widely read portion of the paper; a well written abstract is often an indication that the entire paper meets the criteria and standards of a good scientific report. Write the abstract after you have finished writing the entire paper, not before. One paragraph maximum or even two or three sentences are optimum lengths. However, the length depends upon the complexity of the subject matter. Fewer than 200 words are usually sufficient. Short papers like rapid communications, laboratory notes, and letters to the editor may have one-sentence abstracts, in which case the sole sentence would be the purpose of the paper. The reader is looking for the purpose of the experiment, the plan, the most important findings, and conclusion, but the abstract must avoid anything not confirmed in the paper. The first sentence must state what you did in your experiment or the purpose of the paper; it must not be an introduction to a subject or a problem (as it does not tell the reader what was done or accomplished in your experiment); example of an appropriate first sentence: “Time-resolved synchrotron powder diffraction was used to follow the 57

thermal transformation of cement-asbestos.” The next sentences should give the principal results. Background information relating to why the study was done may be included; otherwise such information belongs in the introduction section. Experimental details, including instrumentation and parameters, should be in the experimental section of the paper. Because an abstract must stand alone from the rest of the paper, do not refer to equations, figures, tables, or cited sources. It is, however, the correct place to use abbreviations used later in the body of the paper. 2. Key words

Include a set of no note than six key words/terms below the abstract (on same page); not required for letters to the editor, erratum, contributions to international reports or to the calendar. Select the terms carefully as these will help researchers and readers locate your article during bibliographic searching and indexing. All words in the list should be lowercase (except proper names and chemical formulas) and separated by commas. 3. General format

The rest of the paper should include the usual sections appropriate for such a paper, including, but not limited to, an introduction, experimental, results and discussion, and conclusion section. Sections must be numbered as shown in Figure 1.

Figure 1. Levels of Section headings.

Shorter papers like rapid communications, laboratory notes, and letters to the editor may not have sections. Other notes about section headings are as follows: . References and footnotes are not allowed in headings . Rename any headers named CONCLUSIONS to CONCLUSION . If acknowledging only one person or place the heading is left singular (ACKNOWLEDGMENT); if acknowledging more than one, it should be plural (ACKNOWLEDGMENTS) . Do not number the acknowledgment(s) heading Double space the text and number the sections as seen in this document. Use 12-point size Times or Times New Roman font; if special symbols or Greek letters are used, avoid using nonstandard fonts as this may lead to errors in transmission and conversion. 4. Style

Proper style according to the points below and the examples in Table I should be used. Be consistent throughout the paper. For more information please refer to the Cambridge University Press Style Guide: www.cambridge.org/us/notesforauthors/cambridge_style.doc. Acronyms do not need to be defined, especially common ones like XRD. It is not necessary to change appropriate text throughout to its acronym, unless such presentation is distracting (like the text is too long). 58

Italics are used to denote text in foreign languages, variables in equations, and to distinguish between elements and non elements. Greek letters and foreign words, including species names in Latin, should be in italics. Ab initio, in situ, in vitro, in vivo, ibid., and et al. should be in italics, but e.g., etc., i.e., viz., and vs. are not in italics. Single letter variables should be in italics (x = 50, not x = 50); hkl should be in italics. Letters in space groups should be in italics, but not numbers (P21/c). Use of letters to denote a series of elements or something other than an element should in general be in italics. This is important as some authors like to use the letter B to denote something other than boron. Letters A, M, and R are also frequently used to denote a series of elements (note that these letters are not assigned in the periodic table). For example, consider A2BV3O11 (A = Mg, Zn and B = Ga, Fe, Cr)—letter A is not an assigned letter in the periodic table and letter B does not refer to boron. CuKα is written as such because letter K does not refer to potassium and α is a Greek letter. Figure and table should be spelled out, but not Equation (Eq.). Space group should not be abbreviated SG. Pay special attention to the presentation of units of measure. These, if preceded by a number, should be abbreviated. There should be a space between the number and units (10 mm, not 10mm), except for the percent sign (22%) and degrees sign without Celsius of Fahrenheit (84°). Do not repeat the units if only a word separates two numbers of the same unit (10 and 14 mm, not 10 mm and 14 mm). Variables and their units in table column headings or figure axis labels should be written like x (%), not x/%.

TABLE I.

Examples of style errors corrected.

Not acceptable

Acceptable

β Homo sapiens Fm*** Iobs Biso Rp NdMMgMn2O6 (M = Li,Na,K,Cs) CuKα Fig. 1a Figures 1a, b Table 1 S.G. 60 hours 600°C 3GPa 22 % 84 ° 14.842(4)Å V/Å3 Melting point/°C between 2–6 mm from 8°C-10°C Equations 2–5 (see Eq. (2))

β Homo sapiens Fm*** Iobs Biso Rp NdMMgMn2O6 (M = Li,Na,K,Cs) Cu Kα Figure 1(a) Figures 1(a) and 1(b) Table I space group 60 h 600 °C 3 GPa 22% 84° 14.842(4) Å V (Å3) Melting point (°C) between 2 and 6 mm from 8 to 10 °C Eqs. (2)–(5) [see Eq. (2)]

59

A hyphen/minus (−) or en dash (–) should not be used to denote a range in running text; for example use between x and y, not between x–y; use from x to y, not from x–y; using an en dash is acceptable for dates, to denote a range of figures, tables, or equations, or when space is an issue like in table columns. Note that when a dash is to be used to denote a range, use en dash (–) not hyphen/minus (−). The exact symbol or special character must be used—correct any substitutions. For example, authors will commonly superscript small letter o to mimic the degrees symbol. This is unacceptable—the real degrees symbol must be used. See Table II for examples. Since it is difficult to see the difference in many cases, it’s suggested that anytime you come across a special character, insert the proper symbol as if the original were incorrect. TABLE II.

Misuse of simple characters as substitution for special characters corrected.

Not acceptable

Acceptable

°C [using superscript letter o for degrees] um [substituting letter u for Greek letter mu] x [using letter x for multiplication or dimensions] ≤ [underlining < for less-than or equal to] e [using small letter e without the acute]

°C μm × ≤ é

5. Mathematics

Mathematical expressions introduced in your paper must be on a separate line and numbered: [Equation] [Equation in appendix]

(1) (A1)

Do not use mathematical derivations when they are easily located elsewhere in the literature, but merely cite the appropriate reference(s). 6. Acknowledgement(s)

If you wish to acknowledge specific people, state their affiliation. Do not just state their name; an affiliation will help identify the acknowledged if unknown to the reader. Do not acknowledge reviewers or the staff of this journal. Place the acknowledgements section after the running text but before the references, and do not number the section with a Roman numeral. B. References

References must be cited in text using the author’s last name and year of publication (do not use the numerical format). For example, a reference with one author would be cited in text like this: (de Wolff, 1968); with two authors: (Smith and Snyder, 1979); with three or more authors: (McMurdie et al., 1986). Use a semicolon (;) to separate multiple references in the same sentence: (de Wolff, 1968; Smith and Snyder, 1979; McMurdie et al., 1986). If you mention the authors name as part of the sentence, then only the year is in parenthesis: McMurdie et al. (1986). In referring to two or more of the same author’s works published in the same year, distinguish between them in text and in the references list with a lowercase letter after the year (2000a, 2000b, 2000c. . .). This is important so the reader knows exactly which citation is being referenced. The citation noted as “a” is the one that comes before “b” in the references list in proper order—it is not necessarily the first one cited in text. 60

References must include the names of all authors, the title of any journal or book article and must be listed alphabetically by the last name of the first author in a separate section at the end of the text. The order of presentation generally should be author(s)’ last names, including the initials of given names, year of publication, article title, journal, volume, and inclusive pages. Examples of citations in proper format follow. More can be found at: http://www.icdd.com/resources/pdj/Commonly%20Cited%20Sources.doc 1. Journal article

Shannon, R. D. (1976). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 32, 751–767. Shannon, R. D. (1976). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 32, (In press). Shannon, R. D. (Submitted). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. Shannon, R. D. (In progress). “Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides,” Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 2. Book

Buhrke, V. E., Jenkins, R., and Smith, D. K. (Eds.) (1998). A Practical Guide for the Preparation of Specimens for X-ray Fluorescence and X-ray Diffraction Analysis (Wiley, New York). Klug, H. P. and Alexander, L. E. (1974). X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials (Wiley, New York), 2nd ed., p. 966. 3. Selection from an anthology

Snyder, R. and Bish, D. L. (1989). “Quantitative analysis by X-ray powder diffraction,” in Modern Powder Diffraction, edited by D. L. Bish and J. E. Post (Mineralogical Society of America, Washington), Vol. 20, pp. 101–144. 4. Report

Larson, A. C. and Von Dreele, R. B. (2000). General Structure Analysis System (GSAS) (Report LAUR 86-748). Los Alamos, New Mexico: Los Alamos National Laboratory. 5. Computer program

Coelho, A. A. (2007). TOPAS-Academic, version 4.1 (Computer Software), Coelho Software, Brisbane. A list of notable and commonly referred to citations is located at http://www.icdd. com/resources/pdj/authors.htm. A few references also appear at the end of this document. 6. Databases and Powder Diffraction File

The format for citing a database is as follows: First, A. A. (Year). Name of database (Database), Company Name City, State, Country. First, A. A. and Second, B. B. (Year). Name of database (Database), Company Name City, State, Country. Company as author (Year). Name of database (Database), edited by A. A. First, City, State, Country. When referring to Powder Diffraction File (PDF) numbers please refer to the source in text as “PDF XX-XXX-XXXX (ICDD, Year)”. 61

To cite the PDF Data Book, follow the format for citing a book. For example, cite the Data Book issued in 2010 as follows: ICDD (2010). Powder Diffraction File Inorganic and Organic Data Book, edited by Dr. Soorya Kabekkodu (International Centre for Diffraction Data, Newtown Square, PA USA), Set 60. To cite the PDF relational databases, follow the format for citing a database. For example, cite the PDF-4/Organics 2011 database released in 2010 as follows: ICDD (2010). PDF-4/Organics 2011 (Database), edited by Dr. Soorya Kabekkodu, International Centre for Diffraction Data, Newtown Square, PA, USA. Please cite the PDF-4+ 2010 database as follows: ICDD (2010). PDF-4+ 2010 (Database), edited by Dr. Soorya Kabekkodu, International Centre for Diffraction Data, Newtown Square, PA, USA For questions regarding citing PDF products in Powder Diffraction, please contact the managing editor, Nicole M. Ernst Boris ([email protected]) or 610-325-9814.

C. Tables

Extensive numerical material should be presented in tables rather than in the body of the text. Each table should be numbered with a Roman numeral (I, II, III. . .) and produced at the end of the running text (after references). Each table must have a caption that makes the data in the table intelligible without reference to the text. Avoid complicated column headings. If necessary, use symbols that are explained in the caption or in the table footnotes. Place the caption above the table, and single space the table and caption (do not double space). Each table should be listed under the heading “Tables” after the references list.

D. Figures

Figures published in the journal are received electronically from the author, and integrated with the text of the article, creating completely electronic pages. Please adhere to the following guidelines when preparing your illustrations so that the files are of production quality. Figure files must be in encapsulated postscript (EPS) or tagged image file (Tif/Tiff). No other format is acceptable, including JPEG, JPG, GIF, PDF or application files such as Corel Draw. Images embedded in word processor files cannot be accepted. Please see http://dx.sheridan.com/guidelines/digital_art.html for more information. Create illustrations using these settings: Line artwork Format: tif or eps Colour mode: black and white (also known as 1-bit) Resolution: 1200 dpi Combination artwork (line/tone) Format: tif or eps Colour mode: grayscale (also known as 8-bit) Resolution: 800 dpi 62

Black and white halftone artwork Format: tif Colour mode: grayscale (also known as 8-bit) Resolution: 300 dpi Colour halftone artwork Format: tif Colour mode: CMYK colour Resolution: 300 dpi Make sure there is one figure per file. Each figure file should include all parts of the figure but without figure caption. For example, if Figure 1 contains three parts [(a), (b), (c)], then all of the parts should be combined in a single file for Figure 1. The parts should be label as such. The captions of all figures should be listed together in a separate page after the tables. When submitting your paper, do not embed the figures with the text of the paper inside the word processor file. Upload the individual figure files as noted in the submission guide.

E. Supplemental Data

Supplemental data should be submitted via ScholarOne along with your manuscript and figure files. CUP will assign one digital object identifier (DOI) to the published article. Supplemental material now gets deposited and linked with the DOI for the article, allowing easier access to all material by one click of the mouse. These data are also deposited with ICDD and are subject to the same copyright laws as the manuscript. Please note that the supplemental data of the digital form of each experimental diffraction pattern used in a new-diffraction-data paper are now required to be submitted via ScholarOne along with its article and figure files. Submission of the supplemental data of each digital observed XRD pattern used in a crystal-structure article is also encouraged. To submit supplemental data, simply choose “Supplementary Material (online publication only) when uploading those files. It is recommended to use of common file types, such as .DOC and .PDF, to provide simplistic retrieval. Once the manuscript is approved, all files are forwarded by the managing editor to CUP. For assistance or questions regarding supplemental data, please contact the managing editor at boris@icdd. com. For technical assistance, please use the ‘Get Help Now’ link on your ScholarOne Manuscripts site to submit a support case or follow this link: http://mchelp.manuscriptcentral.com/gethelpnow/question.htm.

VI. PROOFS A. Process

Page proofs of articles will be sent by CUP directly to the corresponding author by e-mail. Notification may take several weeks after the paper is received by CUP. All corrections, revisions, and additions must be communicated by a single e-mail reply. The proof should be checked with the utmost care, especially tables, equations, formulas, and symbols. Check the last page of the proof for notes and requests from CUP. Ultimate responsibility for detecting errors resides with the author. Proofs should be done in a timely manner so that there will be no production delays. 63

B. Free color figures online

If authors supply usable color graphics files in time for the production process, color will appear in the online journal free of charge. Usable color graphics files must be created by the authors as described above. Figures will continue to appear in black and white in the print version with a notation “(Color online)” in the caption to alert readers that color is available online. Authors may not submit two versions of the same illustration (for example, one in color and another in black and white). When preparing illustrations that will appear in color in the online journal and in black and white in the printed journal, authors must ensure that colors chosen will reproduce well when printed in black and white, and descriptions of figures in text and captions will be sufficiently clear for both print and online versions. This is the author’s responsibility. If color figures submitted are of acceptable quality, authors will see color versions of those illustrations when viewing their author proofs. At the proof stage and if not already included, authors must insert the phrase “(Color online)” into the captions of color figures. Authors can simply state in the reply e-mail which figures are color online, but this must be done by the author (color online notation may also be included in the figure caption prior to submission). Example of an amended figure caption: Figure 10. (Color online) Experimental (dotted curve) and simulated (solid curve) X-ray diffraction spectra.

VII. NOMENCLATURE In general, the nomenclature should conform to recommendations established by the appropriate international body. Crystallographic nomenclature should follow the recommendations of the International Union of Crystallography (IUCr). The naming of compounds should conform to the recommendations of the International Union of Pure and Applied Chemistry (IUPAC), International Union of Biochemistry (IUB), or other appropriate bodies. Mineral names should conform to the recommendations of the International Mineralogical Association (IMA). Any accepted trivial name, trademark, recommended International Non-Proprietary Name, United States Adopted Name, or British Pharmacopoeia Approved Name may be retained, but the corresponding systematic IUPAC name should always be provided. For complex organic compounds, a figure containing the structural formula of the molecule(s) is recommended. Nomenclature for X-ray emission lines is in a state of transition. For new compounds, the author should obtain the CAS (Chemical Abstract Service) number assigned to that compound.

VIII. DATA PRESENTATION AND DOCUMENTATION For papers that include powder diffraction data, follow these guidelines. A. Introduction

The introduction section should discuss the reasons for scientific or industrial interest in the crystalline phase(s). It should note any existing powder diffraction patterns, especially those in the PDF. A figure showing a structural formula is requested for all but the simplest organic molecules in a phase. B. Experimental methods 1. Sample

If synthesized, describe procedure; include any specimen pre-treatment. If a mineral, give locality and any associated minerals and physical description (color, hardness, optical data, etc.). 64

2. Specimen preparation

Describe the procedure used for powdering the specimen (mortar and pestle grinding, filing for metals followed by annealing, etc.), and give an indication of grain size. Note the type of specimen [smear on glass slide; front-loaded pressed powder; side-drifted in Al well (McMurdie et al., 1986)]. 3. Standard

Indicate whether external or internal. Give name and origin of standard. Give unit-cell parameter(s) used in calibrations to full precision. For quantitative analyses using an internal standard, give details of the amount of internal standard added and the method used to ensure total mixing of the sample with the internal standard. 4. Data collection

Include the following information: 1. Radiation and values of wavelength(s) used in angle-to-d conversions; Powder Diffraction now uses 1.5406 Å (or 0.15406 nm) for Cu Kα1 radiation for all purposes, except when the author makes a case for the use of an alternate value. 2. Instrument power: kV, mA. 3. Mean temperature of measurement. 4. For diffractometer data, providing the name and model of the instrument is encouraged because of the information this conveys to knowledgeable readers about instrument resolution, sensitivity, etc. 5. Theta compensating slit? If so, equivalent fixed-slit Is must be reported. 6. Filter or monochromator—diffracted beam or incident beam. 7. 2θ scan range. 8. If an automated powder diffractometer was used, give step size and count time at each step, and note whether smoothing or α2 stripping was performed (it is important to report whether α2 stripping was done, because relative intensities will differ markedly from the intensities where stripping has not been done). 9. Camera data: diameter and other camera particulars; incident beam monochromator or filter; shrinkage and absorption corrections performed. 5. Data reduction

Include the following information: 1. Peak finding program, peak finding method, or both. 2. Least-squares refinement program used and other particulars on the refinement. 3. Source of initial cell (crystallographic database, single-crystal technique, etc.) or indexing program [give programs and FOMs of indexing, for example FN (Smith and Snyder, 1979) and M20 (de Wolff, 1960)]. C. Results and discussion

A figure with a complete diffraction pattern, or a selected range, is desirable in many papers, because of the information conveyed in the profiles that is lost during numerical data reduction. The ICDD is now archiving digital diffraction patterns for possible future publication as a supplement to the numerical PDF entry. With the knowledge of the instrument and data reduction given in the manuscript, the ICDD will be able to convert most file formats into archival format. In most articles, especially those for new diffraction data, a table for powder diffraction data should be included. The data columns listed in the table are: 2θobs, dobs, Iobs, (hkl), 2θcal, dcal, Ical and Δ2θ (i.e., 2θobs - 2θcal). Values of 2θobs, d obs and I obs are determined from the experimental diffraction pattern, while values of 2θcal, dcal and Ical are calculated from refined unit-cell parameters and Miller indices 65

(hkl). The Icalc column can be omitted if calculated intensities are unavailable. The submitted powder diffraction data will be checked by an editorial and database building code known as SQLAIDS. When this program indicates problems with the powder data, authors will be provided with a copy of the program output. The angle 2θ is the preferred entry to the computer database, and from it dobs will be calculated from the wavelength value given for the X-ray source. The 2θ reported are the values after correction for systematic errors, providing the dobs data used in the least-squares refinement permits an additional editorial check. Note: authors should be aware of a small systematic error in some computer peak-finding programs where the α doublet is not resolved. By converting to d with a single wavelength (either α or α1), a systematic error is introduced. Because SQLAIDS uses only one wavelength, all peak 2θ positions read as α values should be converted to the α1 values corresponding to dobs in the submitted data table. Note that this problem is eliminated when α2 stripping is performed and all angle-to-d conversions are done with a single wavelength. Crystal data for the refined unit-cell parameters [unit-cell parameters with estimated standard errors, space group, formula units/unit cell (Z), and calculated density (ρx)] may be included in the abstract without repetition in the text. FN (Smith and Snyder, 1979) and/or M20 (de Wolff, 1960) should be included too. The corundum reference intensity ratio (I/Ic) is a desirable component of a powder diffraction data article, because it is useful for semi-quantitative estimation of the amounts of phases in mixtures. The computer pattern modeling code POWD by Smith et al. (1983) provides a calculated I/Ic, which can be included for comparison to the observed value. In the case that the powder pattern for the phase has been previously published in the literature, in the PDF, or both, a discussion of the improvements provided by the new powder pattern should be given. Here are a few preferred terms for powder diffraction pattern papers: sample for the aliquot of the phase before grinding, specimen for the material placed in the diffractometer or camera, reflection when referring to a Bragg reflection with a specific (hkl), peak when referring to a peak in a diffraction pattern, which may consist of several overlapped, but not resolved, reflections, and unit-cell parameters instead of lattice constants or lattice parameters.

REFERENCES McMurdie, H. F., Morris, M. C., Evans, E. H., Paretzkin, B., and Wong-Ng, W. (1986). |at“Methods of producing standard X-ray diffraction powder patterns,” Powder Diffr. 1(1), 40–43. Smith, D. K., Nichols, M. C., and Zolensly, M. E.(1983). POWD10, a Fortran IV program for calculating X-ray powder diffraction patterns (Computer Software), Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania. Smith, G. S. and Snyder, R. L. (1979). |at“FN: A criterion for rating powder diffraction patterns and evaluating the reliability of powder-pattern indexing,” J. Appl. Crystallogr. 12, 60–65. de Wolff, P. M. (1968). “A simplified criterion for the reliability of a powder pattern indexing,” J. Appl. Crystallogr. 1, 108–113.Link does not work

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CUMULATIVE AUTHOR INDEX All authors published so far in the current volume are listed alphabetically with the issue and page numbers following the dash. A cumulative author and subject index covering each volume is published annually. An (E) after the page number indicates Erratum.

Beauparlant, Martin – (1) 12 Belaaouada, S. – (1) 32

Huang, Q. – (1) 25

Poleti, Dejan – (1) 2

Kaduk, J. A. – (1) 25 Kaduk, James A. – (1) 46 Karanović, Ljiljana – (1) 2 Kheïreddine, A. – (1) 32

Reid, J. W. – (1) 20

Ernst Boris, Nicole M. – (1) 1

Lesage, Jacques – (1) 12 Levin, I. – (1) 25

Van Tra, Huu – (1) 12

Faber, J. – (1) 20 Fawcett, T. G. – (1) 20 Fortes, A. Dominic –(1) 8

Martin, Joannie – (1) 12 Messick, Julian – (1) 36

Woicik, J. C. – (1) 25 Wong-Ng, W. – (1) 25 Wong-Ng, Winnie – (1) 50 Wood, Ian G. – (1) 8

Guru Row, T. N. – (1) 45

Needham, F. – (1) 20

Yang, Jihui – (1) 25

Crowder, C. E. – (1) 20 Dapčević, Aleksandra – (1) 2 Delgado, José Miguel – (1) 48

67

Shi, X. – (1) 25 Tridane, M. – (1) 32