Synthesis and Characterization of -Fe2O3

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Synthesis and Characterization of γ-Fe2O3 Nanoparticles. L. JAYARATHNA1 ... bands at 627 and 451 cm-1 are typical for ferrihydrite or γ-Fe2O3 nanoparticles.
Synthesis and Characterization of -Fe2O3 Nanoparticles L. JAYARATHNA1,2, R. WEERASOORIYA1 AND A. BANDARA1 1

Department of Chemistry, Faculty of Science, University of Peradeniya, Sri Lanka 2

CML, Institute of Fundamental Studies, Kandy, Sri Lanka

Increasing efforts have been developed to the potential applications of magnetic nanoparticles in various fields, such as information storage, colour imaging, bio-processing, catalysts, magnetic refrigeration, magnetic resonance imaging and medicinal applications1. Most of the case, superparamagnetic nanoparticles of iron oxides, magnetite (Fe3O4) and maghemite (-Fe2O3) have been employed. Their interesting magnetic properties are due to finite-size effects and high surface/volume ratio. Ferromagnetic iron oxide was synthesized by using modified co-precipitation method and resulting particles were characterized using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Diffused Reflectance Fourier Transform-Infrared Spectroscopy (DRIFT-IR) and Thermal Gravimetric Analysis (TGA)2. The XRD pattern matches well that of -Fe2O3. Six characteristic peaks for -Fe2O3 (2θ = 31.7, 36.7, 41.1, 53.4, 57.0 and 62.6) marked by their Miller indices ((220), (311), (400), (422), (511) and (440)) were observed for sample. Figure 1 shows the TEM image of the synthesized Fe2O3 nanoparticles. This reveals that the particles are in 5 – 20 nm range, and well fitted with spaniel cubic structure, but when particles are dry it prefer to agglomerate with neighbouring particles to reduce their surface charges. Figure 2 shows the DRIFT spectrum of bare -Fe2O3 nanoparticles where three main regions can be observed. Those regions are 3000 to 3600 cm-1, 1250-2000 cm-1 and 400-1250 cm-1. The spectrum of -Fe2O3 nanoparticles shows a characteristic broad band at 3410 cm-1 is due to the stretching vibration of H2O molecules. The band corresponding to the bending vibrations of H2O molecules is positioned at 1633 cm-1. Two intense IR bands at 627 and 451 cm-1 are typical for ferrihydrite or -Fe2O3 nanoparticles. The spectrum of this sample showed the presence of carbonate groups on the basis of IR bands at 1508, 1340 and 1069 cm-1. The presence of carbonate groups is due to the adsorption of atmospheric carbon dioxide by -Fe2O3 nanoparticles. The bands of Fe–O stretching vibrations of -Fe2O3 appeared at 627 and 451 cm-1 and the bands at 892 and 796 cm-1 can be assigned to Fe-OH···H bending vibrations3. Magnetic Fe2O3 nanoparticles were synthesized by the co-precipitation method and this work confirmed that magnetic Fe2O3 nanoparticles are in nano-scale and well matches with spaniel cubic structure.

[1] Yu S. and G.M. Chow., 2004, Carboxyl group (-CO2H) functionalized ferrimagnetic iron oxide nanoparticles for potential bio-applications., J. Mater. Chem., 14. 2781-2786. [2] Jeong J.R. Lee S.J. Kim J.D. and Shin S.C., 2004, Magnetic properties of -Fe2O3 nanoparticles made by co precipitation method., Phys. Stat. Sol., B241, No. 7. 1593-1596. [3] Zic M. Ristic M. and Music S., 57Fe Mossbauer, 2007, FT-IR and FE SEM investigation of the formation of hematite and goethite at high pH values., J. Molecular Structure., 834–836. 141–149.

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