Please use this identifier to cite or link to this item: http://cimav.repositorioinstitucional.mx/jspui/handle/1004/526
Application of x-ray absorption fine structure (XAFS) to local-order analysis in Fe-Cr maghemite-like materials
LUIS EDMUNDO FUENTES COBAS
MARIA ELENA MONTERO CABRERA
MARIA ELENA FUENTES MONTERO
Acceso Abierto
Atribución-NoComercial-SinDerivadas
http://dx.doi.org/10.1063/1.4927185
The maghemite-like oxide system γ-Fe2-xCrxO3 (x=0.75, 1 and 1.25) was studied by X-ray absorption fine structure (XAFS) and by synchrotron radiation X-ray diffraction (XRD). Measurements were performed at the Stanford Synchrotron Radiation Lightsource at room temperature, at beamlines 2-1, 2-3 and 4-3. High-resolution XRD patterns were processed by means of the Rietveld method. In cases of atoms being neighbors in the Periodic Table, the order/disorder degree of the considered solutions is indiscernible by “normal” (absence of “anomalous scattering”) diffraction experiments. Thus, maghemite-like materials were investigated by XAFS in both Fe and Cr K-edges to clarify, via short-range structure characterization, the local ordering of the investigated system. Athena and Artemis graphic user interfaces for IFEFFIT and FEFF8.4 codes were employed for XAFS spectra interpretation. Pre-edge decomposition and theoretical modeling of X-ray absorption near edge structure (XANES) transitions were performed. By analysis of the Cr K-edge XANES, it has been confirmed that Cr is located in an octahedral environment. Fitting of the extended X-ray absorption fine structure (EXAFS) spectra was performed under the consideration that the central atom of Fe is allowed to occupy octa- and tetrahedral positions, while Cr occupies only octahedral ones. Coordination number of neighboring atoms, interatomic distances and their quadratic deviation average were determined for x=1, by fitting simultaneously the EXAFS spectra of both Fe and Cr K-edges. The results of fitting the experimental spectra with theoretical standards showed that the cation vacancies tend to follow a regular pattern within the structure of the iron-chromium maghemite (FeCrO3).
2015
Documento de trabajo
Inglés
Montero-Cabrera, M. E., Fuentes-Cobas, L. E., Macías-Ríos, E., & Fuentes-Montero, M. E. (2015, July). Application of x-ray absorption fine structure (XAFS) to local-order analysis in Fe-Cr maghemite-like materials. In AIP Conference Proceedings (Vol. 1671, No. 1, p. 020008). AIP Publishing.
BIOLOGÍA Y QUÍMICA
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