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The crystal and melt structure of spinel and alumina at high temperature: An in-situ XANES study at the Al and Mg K-edge |
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| Authors: | Daniel R Neuville Dominique de Ligny Grant S Henderson Anne-Marie Flank |
| Institution: | a Physique des Minéraux et Magmas, Géochimie et Cosmochimie, IPGP-CNRS, 4 place Jussieu, 75005 Paris, France b Université de Lyon, Université Lyon 1, CNRS, UMR 5620, Laboratoire de Physico-Chimie des Matériaux Luminescents, 12 rue Ampère, F-69622 Villeurbanne, France c IMPMC, Université Pierre et Marie Curie, Université Denis Diderot, CNRS, UMR 7590, 140 rue de Lourmel, 75015 Paris, France d Department of Geology, University of Toronto, 22 Russell St., Toronto, Canada e Synchrotron SOLEIL, BP 48, 91192 Gif sur Yvette, France |
| Abstract: | We present structural information obtained on spinel and alumina at high temperature (298-2400 K) using in-situ XANES at the Mg and Al K-edges. For spinel, 4](Alx,Mg1−x)6](Al2−x,Mgx)O4, with increasing temperature, a substitution of Mg by Al and Al by Mg in their respective sites is observed. This substitution corresponds to an inversion of the Mg and Al sites. There is a significant change in the Al K-edge spectra between crystal and liquid, which can be attributed to a change of the 6]Al normally observed in corundum at room temperature, to a mixture of 6]Al-4]Al in the liquid state. This conclusion is in good agreement with previous 27Al NMR experiments. Furthermore, both experiments at the Al and Mg K-edges are in good agreement with XANES calculation made using FDMNES code. |
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