Structural and optical properties of microwave assisted CdO-NiO nanocomposite K. Karthik and S. Dhanuskodi Citation: AIP Conference Proceedings 1731, 050021 (2016); doi: 10.1063/1.4947675 View online: http://dx.doi.org/10.1063/1.4947675 View Table of Contents: http://scitation.aip.org/content/aip/proceeding/aipcp/1731?ver=pdfcov Published by the AIP Publishing Articles you may be interested in To study the effect of dopant NiO concentration and duration of calcinations on structural and optical properties of MgO-NiO nanocomposites AIP Conf. Proc. 1728, 020193 (2016); 10.1063/1.4946244 Effect of transition metal ion (Ni) doping on the structural, optical and electrical properties of CdO thin films by spray pyrolytic technique AIP Conf. Proc. 1665, 080028 (2015); 10.1063/1.4917932 Electronic and optical properties of graphene and graphitic ZnO nanocomposite structures J. Chem. Phys. 138, 124706 (2013); 10.1063/1.4796602 Microwave absorption properties of NiCoFe2O4-graphite embedded poly(o-phenetidine) nanocomposites AIP Advances 1, 032157 (2011); 10.1063/1.3642603 Preparation and Optical Properties of CdTe/CdOnH2O Core/shell Nano-composites in Aqueous Solution Chin. J. Chem. Phys. 20, 779 (2007); 10.1088/1674-0068/20/06/779-783
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Structural and Optical Properties of Microwave Assisted CdO-NiO Nanocomposite K. Karthik and S. Dhanuskodi* School of Physics, Bharathidasan University, Tiruchirappalli-620 024, Tamilnadu, India * Email:
[email protected] Abstract. CdO-NiO nanocomposite was prepared by microwave assisted method and characterized by XRD, SEM and FTIR. It exhibits cubic structure with an average crystallite size of 45 nm (CdO), 25 nm (NiO) and 30 nm (CdO-NiO). The average dislocation density (δ) is 4.938 X1014 lines/m2 (CdO), 16.0 X1014 lines/m2 (NiO) and 11.11 X1014 lines/m2 (CdO-NiO). From the UV – Vis spectra, the optical energy band gap is estimated as 2.35 eV (CdO), 3.85 eV (NiO) and 3.75 eV (CdO-NiO). Keywords: Microwave assisted method, nanocomposite, X-ray diffraction, scanning electron microscopy. PACS: 81.16. BC, 78.67 Sc, 61.05 cp, 68.37 HK.
INTRODUCTION
and ethanol and placed again in the oven for 10 minutes. The product was annealed at 873 K for 2 h.
Recently many studies have demonstrated that oxide semiconductor composites show excellent gas sensing properties [1]. Cadmium oxide (CdO) is a well-known n-type II-IV semiconductor (cubic, 2.5 eV). This is a promising catalyst for opto-electronic applications, viz transparent electrodes, solar cells, phototransistors, photodiodes and gas sensors [2]. Nickel oxide (NiO) is a p-type semiconductor (cubic, 3.5 eV). It has a wide technological applications, such as magneto-resistance sensors, electrochemical devices, transparent conducting films and chemical sensors. CdO- NiO nanocomposite with nanofibers has been reported as glucose sensors [3].
Preparation of CdO-NiO nanocomposite CdO-NiO nanocomposite was prepared by facile microwave assisted method. The solutions A and B were mixed under vigorous stirring. This solution was placed in the domestic microwave oven for 15 minutes. The product was washed with double distilled water, ethanol and irradiate for 10 minutes. Eventually, the CdO-NiO nanocomposite was obtained after annealing at 873 K for 2 h.
EXPREMENTAL PROCEDURE
Structural and morphological characteristics
Preparation of CdO and NiO nanoparticles 0.5 M of Cd(CH3COO)2.4H2O was dissolved in 20 ml of double distilled water. 1 M of NaOH was dissolved in 20 ml of double distilled water and added to the above solution under stirring for 15 minutes (A). The stirred solution was placed in a domestic microwave oven (2.45GHz, 800W) for 10 minutes. The precipitate was washed with double distilled water and ethanol and placed again in the oven for 10 minutes. The product was annealed at 673 K for 4 h.
XRD pattern reveals the cubic CdO (JCPDS: 65 -2908), cubic NiO (JCPDS: 89-7130) and cubic CdO-NiO (JCPDS: 65-2908 & 89-7130). No other impurity diffraction peaks are observed, indicating that the formation of CdO-NiO nanocomposite. The crystallite size of the synthesized product is estimated using Debye Scherrer’s formula. (1)
0.5 M of Ni(CH3COO)2.4H2O was dissolved in 20 ml of double distilled water. 1 M of NaOH was dissolved in 20 ml of double distilled water and added to the above solution under stirring for 15 minutes (B). The stirred solution was placed in a domestic microwave oven (2.45GHz, 800W) for 10 minutes. The precipitate was washed with double distilled water
Results and discussion
where k is a constant (0.94), λ is the X-ray wavelength (1.5406 Å), θ is the glancing angle, β is the full width at half maximum (FWHM). The average crystallite size of CdO (45 nm), NiO (25 nm) and CdO-NiO (30 nm) is calculated. The Williamson-Hall method was followed to find the lattice strain using the modified Scherrer equation [4]. (2)
DAE Solid State Physics Symposium 2015 AIP Conf. Proc. 1731, 050021-1–050021-3; doi: 10.1063/1.4947675 Published by AIP Publishing. 978-0-7354-1378-8/$30.00
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The W-H plot of βcosθ against 4sinθ provides the information about the microstrain (Fig. 2). The W – H plot is expected to be a horizontal line, parallel to the sinθ axis, whereas in the presence of strain, it has a non-zero slope. The dislocation density (δ) is estimated using the relation and the values are tabulated in Table 1. (3) The morphology of the synthesized samples was observed using SEM. CdO NPs (agglomeration), NiO NPs (flowerlike) and CdO-NiO nanocomposite (nanosheets) are shown in Fig. 3. The elemental composition of the prepared samples were studied by EDS. CdO NPs (Cd and O), NiO NPs (Ni and O). CdO-NiO nanocomposite (Cd, Ni and O) are present (Fig. 3).
FIGURE 2. W-H plot of CdO, NiO and CdO-NiO nanocomposite
FT-IR Analysis The molecular structure was confirmed by FTIR spectra (Fig. 4). The O-H stretching vibration modes at 3424, 3417 cm-1 in all samples are due to the adsorbed water molecules. The peaks at 2497, 2467 cm-1 are associated with the C-H stretching mode on the surface of the products. The C=O asymmetric stretching appears at 1443, 1444, 1445 cm-1 for CdO NPs, NiO NPs and CdO-NiO nanocomposite respectively. The absorption bands at 1152 (NiO NPs), 1159 cm-1 (CdO-NiO) indicate the existence of carbonates. The stretching vibrations of Cd-O are observed at 460 and its overtone 879 (CdO NPs) 698 cm-1 (CdO-NiO). The Stretching vibrations of Ni-O is observed at 488 (NiO NPs), 476 cm-1 (CdO-NiO) [5, 6]. The composite has both the vibrational modes of the individual oxides.
FIGURE 3. SEM and EDS images of CdO, NiO and CdONiO nanocomposite
UV-Vis Analysis The optical properties of the prepared nanocomposite were studied using UV-Vis absorption spectra (Fig.5). CdO NPs show the absorption at 253 nm, whereas NiO NPs absorb strongly at 365 nm. A strong absorption at 339 nm is assigned to the CdONiO nanocomposite. The optical band gap is calculated by using the following relation αhʋ = A (hʋ-Eg)n (4) where A is the characteristic parameter (free of photon energy) for this transition. h is Planck’s constant, ʋ is the frequency of light, E g is the optical energy band gap and n is the parameter which
FIGURE 1. XRD pattern of CdO, NiO and CdO-NiO nanocomposite
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characterizes the transition process involved. The
CONCLUSION Nanoparticles of CdO & NiO, CdO-NiO nanocomposite were synthesized by the microwave assisted method. XRD pattern of nanocomposite demonstrates a mixed phase of face centered cubic CdO and cubic NiO. SEM image shows the nanosheets and the presence of Cd, Ni and O atoms is confirmed by EDS. The FT-IR spectrum represents the characteristic vibrational modes of Cd-O and Ni-O. From the UV-Vis absorption spectrum, the bandgap is 3.75 eV (CdO-NiO) indicating its potential applications in optoelectronics.
ACKNOWLEDGMENTS One of the authors (K K) acknowledges the financial support from the UGC, New Delhi under UGC-BSR fellowship.
FIGURE 4. FTIR spectrum of CdO, NiO and CdO-NiO nanocomposite
REFERENCES
n=2 for direct allowed transition and ½ for indirect allowed transition. The plot of (αhʋ)2 vs hʋ is shown in (Fig. 5)from which the optical energy band gap is estimated by extrapolating the linear part up to zero on the energy axis. The calculated band gap values are tabulated in Table.1 [7, 8].
1.
2. 3. 4. 5. 6.
FIGURE 5. Absorbance and optical energy bandgap of CdO, NiO and CdO-NiO nanocomposite
7.
TABLE 1: The lattice parameter, strain dislocation density and bandgap Lattice parameter a (Å)
Lattice strain (Ɛ)
Dislocation density (δ) X 1014 lines/m2
Band gap Eg (eV)
4.689
0.0018
4.94
2.35
4.193
0.0023
16.00
3.85
CdO
4.701
0.0020
6.25
3.75
NiO
4.193
Sample
Phase
CdO
---
NiO
---
CdONiO
0.0048
8.
Chen Wang, Xiaoyang Cheng, Xin Zhou, Peng Sun, Xiaolong Hu, Kengo Shimanoe, Geyu Lu, Noboru Yamazoe, ACS Appl. Mater. Interfaces 6, 12031 (2014). P. Senthilkumar, M. Selvakumar, Purabi Bhagabati, B. Bharathi, S. Karuthapandian, S. Balakumar, RSC Adv., 4, 32977 (2014). Yu Ding, Ying Wang, LiChum Zhang, Heng Zhang, Yu Lei, J. Mater. Chem., 22, 980 (2012). K. Karthik, S. Dhanuskodi, C. Gobinath, S. Sivaramakrishnan, Spectrochimic. Acta Part A: Mol. Biomol. Spectrosc. 139, 7 (2015). D. V. Satish, Ch. Rama Krishna, Ch. Venkata Reddy, U S. UdayachandranThampy, R. V. S. S. N. Ravikumar, Phys. Scripta. 86, 035708 (2012). Lotf Ali Saghatforoush, Mohammad Hasanzadeh, Soheila Sanati, Robabeh Mehdizadeh, Bull. Korean Chem. Soc. 33 (8), 2613 (2012). Zai-xing Yang, Wei Zhong, Yan-xue Yin, Xin Du, Yu Deng, Chaktong Au, You-wei Du, Nanoscale Res Lett 5 961 (2010). K. Karthik, S. Dhanuskodi, C. Gobinath, S. Sivaramakrishnan, IJIRSE, ISSN (Online) 2347-3207, 2(1) 558 (2014).
25.00
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