Structural relaxations around Ti, Cr and Fe impurities in alpha-Al2O3 probed by x-ray absorption near edge structure combined with first-principles calculationsReportar como inadecuado




Structural relaxations around Ti, Cr and Fe impurities in alpha-Al2O3 probed by x-ray absorption near edge structure combined with first-principles calculations - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 LMCP - Laboratoire de minéralogie, cristallographie de Paris 2 ESRF - European Synchrotron Radiation Facility

Abstract : We determine the structural relaxations around paramagnetic impurities Ti, Cr, Fe in corundum alpha-Al2O3, by combining x-ray absorption near edge structure XANES experiments and ab initio calculations. The structural relaxations are found to be very local. We then show that XANES is sensitive to small variations in interatomic distances within the coordination shell of the absorbing atom. The experiments were carried out on single crystals of ruby and sapphires. Linear dichroic signals are essential to characterize the geometry of the impurity site. The calculations were performed within a self-consistent -non muffin-tin- framework, that uses pseudopotentials, plane-wave basis set, and the continued fraction for the absorption cross section.

Keywords : ruby pseudopotentials ab initio calculations K edge XANES angular dependence sapphires impurities structural relaxation





Autor: Emilie Gaudry - Delphine Cabaret - Philippe Sainctavit - Christian Brouder - Francesco Mauri - José Goulon - Andrei Rogalev -

Fuente: https://hal.archives-ouvertes.fr/



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