Raman spectra of bixbyite, Mn2O3, up to 40 GPa

S. H. Shim, D. LaBounty, T. S. Duffy

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The Raman spectra of bixbyite, Mn2O3, were measured up to 40 GPa at room temperature. Mn2O3 undergoes a phase transition from the C-type rare earth structure to the CaIrO3-type (post-perovskite) structure at 16-25 GPa. The transition pressure measured in Raman spectroscopy is significantly lower than the pressure reported previously by an X-ray diffraction study. This could be due to the greater polarizability in the CaIrO3-type structure, consistent with high-pressure observation on the CaIrO3 type in MgGeO3, although it is still possible that experimental differences may cause the discrepancy. Unlike the change at the perovskite to CaIrO3-type transition, the spectroscopic Grüneisen parameter does not decrease at the C-type to CaIrO3-type transition. The spectroscopic Grüneisen parameter of the low-pressure phase (C type) is significantly lower than thermodynamic Grüneisen parameter, suggesting significant magnetic contributions to the thermodynamic property of this material. Our Raman measurements on CaIrO3-type Mn2O3 contribute to building systematic knowledge about this structure, which has emerged as one of the common structures found in geophysically important materials.

Original languageEnglish (US)
Pages (from-to)685-691
Number of pages7
JournalPhysics and Chemistry of Minerals
Issue number9
StatePublished - Oct 2011

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Geochemistry and Petrology


  • Grüneisen parameter
  • MnO
  • Phase transition
  • Raman spectroscopy


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