Pressure-induced Landau-type transition in stishovite

被引:193
作者
Andrault, D
Fiquet, G
Guyot, F
Hanfland, M
机构
[1] Inst Phys Globe, Dept Geomat, F-75252 Paris, France
[2] Ecole Normale Super Lyon, Geol Lab, F-69364 Lyon, France
[3] Univ Paris 07, Lab Mineral Cristallog, F-75252 Paris, France
[4] European Synchrotron Radiat Facil, F-38043 Grenoble, France
关键词
D O I
10.1126/science.282.5389.720
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
A Rietveld structural analysis of stishovite, with angle-dispersive x-ray diffraction synchrotron source at the European Synchrotron Radiation Facility, confirmed a CaCl2 form of stishovite distortion at 54 +/- 1 gigapascals but confirmed no further phase transformation up to 120 gigapascals. The deviatoric stress that is usually encountered at such pressures was relaxed after yttrium-aluminum-garnet-laser heating. A single Birch-Murnaghan equation of state fits volumes of stishovite and a CaCl2 form, showing that the tetragonal distortion occurs without a substantial change in volume. At the 54-gigapascal transition, the pressure-induced Lattice modifications were similar to those found in a Landau-type temperature-induced transition. It is proposed that, above the transition pressure, the critical temperature increases above 300 kelvin, so that the Lower entropy form becomes stable.
引用
收藏
页码:720 / 724
页数:5
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