X-ray absorption fine structure study of amorphous metal oxide thin films prepared by photochemical metalorganic deposition |
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Authors: | Simon Trudel E Daryl Crozier Peter S Budnik |
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Institution: | a Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4 b Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6 c 4D LABS and Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6 |
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Abstract: | The oxidation state and local geometry of the metal centers in amorphous thin films of Fe2O3 (Fe3+ oxidation state), CoFe2O4 (Co2+/Fe3+ oxidation states), and Cr2O3 (Cr3+ oxidation state) are determined using K edge X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. The metal oxide thin films were prepared by the solid-state photochemical decomposition of the relevant metal 2-ethylhexanoates, spin cast as thin films. No peaks are observed in the X-ray diffraction patterns, indicating the metal oxides are X-ray amorphous. The oxidation state of the metals is determined from the edge position of the K absorption edges, and in the case of iron-containing samples, an analysis of the pre-edge peaks. In all cases, the EXAFS analysis indicates the first coordination shell consists of oxygen atoms in an octahedral geometry, with a second shell consisting of metals. No higher shells are observed beyond 3.5 Å for all samples, indicating the metal oxides are truly amorphous, consistent with X-ray diffraction results. |
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Keywords: | Amorphous metal oxides X-ray absorption Thin films XANES EXAFS XAFS Solid-state photochemistry |
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