Structural relaxations around Ti, Cr and Fe impurities in alpha-Al2O3 probed by x-ray absorption near edge structure combined with first-principles 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.
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Journal of Physics: Condensed Matter, IOP Publishing, 2005, 17, pp.5467-5480. <10.1088/0953-8984/17/36/003>
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Soumis le : mercredi 12 janvier 2005 - 17:44:12
Dernière modification le : mardi 11 octobre 2016 - 13:53:27
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Emilie Gaudry, Delphine Cabaret, Philippe Sainctavit, Christian Brouder, Francesco Mauri, et al.. Structural relaxations around Ti, Cr and Fe impurities in alpha-Al2O3 probed by x-ray absorption near edge structure combined with first-principles calculations. Journal of Physics: Condensed Matter, IOP Publishing, 2005, 17, pp.5467-5480. <10.1088/0953-8984/17/36/003>. <hal-00003882>

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