High-resolution synchrotron X-ray powder diffraction and Rietveld structure refinement of two (Mg0.95,Fe0.05)SiO3 perovskite samples synthesized under different oxygen fugacity conditions

A. P. Jephcoat, J. A. Hriljac, C. A. McCammon, H. St C. O'Neill, D. C. Rubie, L. W. Finger

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22 Citations (Scopus)

Abstract

This paper presents high-resolution synchrotron X-ray powder diffraction data at 290 K on two Fe-bearing, polycrystalline silicate perovskite samples with approximate compositions (Mg0.95Fe0.05)SiO3 synthesized at 25 GPa and 1920 K in a multi-anvil press at different oxygen fugacity conditions. Mossbauer studies have indicated that Fe3+/ΣFe for the samples are 0.09 ± 0.01 and near 0.16 ± 0.03. Rietveld structural refinements confirm that Fe2+ and Fe3+ dominantly substitute for Mg2+ in the 8-fold to 12-fold coordinated A site for both compositions. There appears to be no significant differences in the bond distances for these amounts of Fe3+ and no conclusive structural evidence to support indications from Mossbauer experiments that Fe3+ may occupy both A and B sites. To explore the effect of valence state further, this study also reports the first diffraction patterns of (Mg,Fe)SiO3 perovskite collected at a wavelength near the Fe absorption edge.

Original languageEnglish
Pages (from-to)214-220
Number of pages7
JournalAmerican Mineralogist
Volume84
Issue number3
DOIs
Publication statusPublished - Mar 1999

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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