Stability and equation of state of MgGeO3 post-perovskite phase

Kei Hirose, Katsuyuki Kawamura, Yasuo Ohishi, Shigehiko Tateno, Nagayoshi Sata

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Abstract

A phase transition of MgGeO3 perovskite was examined at high-pressure and -temperature using synchrotron X-ray diffraction measurements. The results demonstrate that it transforms to a CaIrO 3-type post-perovskite phase above 63 GPa at 1800 K. The density increase is 1.5% at the transition pressure. These observations confirm that MgGeO3 is a low-pressure analogue to MgSiO3, for which a similar phase transition was recently found above 125 GPa and 2500 K. The unit-cell parameters of MgGeO 3 post-perovskite phase obtained at 300 K during decompression from 79 to 6 GPa show that the b-axis is significantly more compressible than are the a- and c-axes, which could be due to the GeO6-octahedral sheet stacking structure along b. The bulk modulus was determined to be K0 = 192(±5) GPa with a fixed pressure derivative of the bulk modulus, K', of 4.

Original languageEnglish
Pages (from-to)262-265
Number of pages4
JournalAmerican Mineralogist
Volume90
Issue number1
DOIs
Publication statusPublished - Jan 1 2005

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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    Hirose, K., Kawamura, K., Ohishi, Y., Tateno, S., & Sata, N. (2005). Stability and equation of state of MgGeO3 post-perovskite phase. American Mineralogist, 90(1), 262-265. https://doi.org/10.2138/am.2005.1702