Structural relaxations around Ti, Cr and Fe impurities in alpha-Al2O3 probed by x-ray absorption near edge structure combined with first-principles calculations
Emilie Gaudry,Delphine Cabaret,Philippe Sainctavit,Christian Brouder,Francesco Mauri,José Goulon,Andrei Rogalev +6 more
TLDR
In this article, the structural relaxations around paramagnetic impurities (Ti, Cr, Fe) in corundum (alpha-Al2O3) were determined by combining x-ray absorption near edge structure (XANES) experiments and ab initio calculations.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.read more
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The CTM4XAS program for EELS and XAS spectral shape analysis of transition metal L edges
TL;DR: The CTM4XAS program for the analysis of transition metal L edge Electron Energy Loss Spectroscopy (EELS) or X-ray Absorption Spectra (XAS) is explained and a number of examples are presented.
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The 1s x-ray absorption pre-edge structures in transition metal oxides
TL;DR: A general procedure to analyse the pre-edges in 1s x-ray absorption near edge structure (XANES) of transition metal oxides and coordination complexes is developed and large cross section at the 3d-band region due to the strong metal-metal interactions, which are oxygen mediated.
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First-principles calculation of spectral features, chemical shift and absolute threshold of ELNES and XANES using a plane wave pseudopotential method
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Chromium speciation in oxide-type compounds: application to minerals, gems, aqueous solutions and silicate glasses
François Farges,François Farges +1 more
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Theoretical ELNES using one-particle and multi-particle calculations.
TL;DR: In this review, importance of momentum transfer vector in the ELNES calculations for comparison with the experiments is discussed and the basics, methodologies, and some applications of one-, two-, and many-particle calculations are presented.