Publication Date:
1998-10-23
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andrault -- Fiquet -- Guyot -- Hanfland -- New York, N.Y. -- Science. 1998 Oct 23;282(5389):720-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉D. Andrault, Laboratoire des Geomateriaux, Institut de Physique du Globe, Paris 75252, France. G. Fiquet, Laboratoire de Geologie, Ecole Nationale Superieure de Lyon, Lyon 69364, France. F. Guyot, Laboratoire de Mineralogie-Cristallographie〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9784125" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
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Computer Science
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Medicine
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Natural Sciences in General
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Physics
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