Low-pressure climb- to high-pressure clinoenstatite phase transition: A phomom-related mechanism

We have investigated by first principles the compressional behavior of low-pressure (LP) and high-pressure (HP) MgSiO... clinoenstatite. We have carefully examined unit-cell shapes, chain angles, and polyhedral volume responses, such as angle variances and quasi-elongations, under pressure at room t...

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Bibliographic Details
Published inThe American mineralogist Vol. 94; no. 4; p. 461
Main Authors Yu, Yonggang G, Wentzcovitch, Renata M
Format Journal Article
LanguageEnglish
Published Washington Walter de Gruyter GmbH 01.04.2009
Subjects
Atoms & subatomic particles
Mineralogy
Phase transitions
Temperature effects
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Summary:We have investigated by first principles the compressional behavior of low-pressure (LP) and high-pressure (HP) MgSiO... clinoenstatite. We have carefully examined unit-cell shapes, chain angles, and polyhedral volume responses, such as angle variances and quasi-elongations, under pressure at room temperature. We have observed opposite behavior of the tetrahedra in the S-rotated and O-rotated chains with pressure in the LP phase, with a slight increase (decrease) in angle variance and quasi-elongation in the former (latter). Inspection of zone center modes of both phases under pressure reveals a transition path that converts the S-rotated chain in the LP phase into the O-rotated chain in the HP phase. This conversion is related to a slight softening of an A... "metastable" Raman mode under pressure. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0003-004X
1945-3027