Low-pressure clino- to high-pressure clinoenstatite phase transition: A phonon-related mechanism

Yonggang G. Yu, Renata M Wentzcovitch

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

We have investigated by first principles the compressional behavior of low-pressure (LP) and highpressure (HP) MgSiO3 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 Ag "metastable" Raman mode under pressure.

Original languageEnglish (US)
Pages (from-to)461-466
Number of pages6
JournalAmerican Mineralogist
Volume94
Issue number4
DOIs
StatePublished - Apr 1 2009

Keywords

  • High-pressure clinoenstatite
  • Ir
  • Low-pressure clinoenstatite
  • Phase transition mechanism
  • Phonon frequency
  • Raman

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