Silica polymorphs,glass and melt: An in situ high temperature XAS study at the Si K-edge |
| |
| Authors: | D de Ligny DR Neuville L Cormier J Roux GS Henderson G Panczer S Shoval A-M Flank P Lagarde |
| |
| Institution: | 1. Université de Lyon, Université Lyon 1, CNRS UMR 5620 LPCML, 12 rue Ampère, F-69622 Villeurbanne, France;2. Physique des Minéraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75005 Paris, France;3. IMPMC, Université Pierre et Marie Curie, Université Denis Diderot, CNRS UMR 7590, 140 rue de Lourmel, 75015 Paris, France;4. Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario, Canada M5S 3B1;5. The Open University of Israel, Physics and Geology Groups, 16 Klausner St., 61392 Tel-Aviv, Israel;6. Synchrotron SOLEIL, L’Orme des Merisiers, BP48, 91192 Gif s/Yvette cedex, France |
| |
| Abstract: | High temperature X-ray absorption spectra at the Si K-edge were obtained for SiO2 quartz from room temperature up to 2030 K. Important modifications are observed for the XANES spectra. These change are related to rearrangements of the SiO4 tetrahedra beyond the short-range correlations. To interpret these spectral evolutions, SiO2 polymorph samples were observed at room temperature and XANES calculations using FDMNES were performed. Very strong differences are shown between the different polymorphs even between α and β phases for which only small displacive angle rotations of the SiO4 tetrahadra occurs. Therefore the quartz α to β transition could be identified at its expected temperature, 842 K. A badly defined transition toward β-cristobalite is observed between 1670 and 1940 K. The dynamics of this totally reconstructive transition was further investigated on heat treated cherts. Finally the liquid is reached around 2000 K. Many similarities were observed on SiO2 between its glass at room temperature, β-cristobalite and liquid at high temperature. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
