Pressure induced iron spin state changes in MgGeO$_3$ Perovskite and Post-perovskite

ORAL

Abstract

MgGeO$_3$-perovskite is a low pressure analog of MgSiO$_3$-perovskite, the main Earth forming phase, and is used to shed light on several phenomena that occur in MgSiO3, particularly the post-perovskite transition. As such, experimental investigations of spin state changes in Fe-bearing MgGeO$_3$ might help to clarify some aspects of this phenomenon in MgSiO$_3$. Using DFT+U calculations, we have investigated pressure induced spin state changes in Fe$^{2+}$ and Fe$^{3+}$ in MgGeO$_3$ perovskite and post-perovskite and their effect on the post-perovskite transition. We uncover a direct relationship between average Fe-O bond-lengths and spin transition pressures in all cases. The effect of iron on the post-perovskite transitions in these phases can also be related to the average Fe-O bond lengths.

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Authors

  • Kanchan Sarkar

    University of Minnesota Twin cities

  • Gaurav Shukla

    University of Minnesota Twin cities

  • Mehmet Topsakal

    University of Minnesota Twin cities

  • Renata Wentzcovitch

    University of Minnesota Twin cities, Department of Chemical Engineering and Materials Science, and Minnesota Supercomputing Institute,, U of MN -Twin cities, MN, USA, University of Minnesota, Department of Chemical Engineering and Materials Science, U of Minnesota, Twin Cities, Univ of Minn - Minneapolis