Post-perovskite transition in NaMgF$_3$

ORAL

Abstract

We have investigated through first principles computations the pressure-induced behavior of NaMgF$_3$. It has the same Pbnm perovskite structure as MgSiO$_3$, the major lower mantle phase. Likewise MgSiO$_3$ it displays the same post-perovskite transition. Static LDA calculations indicate this transition should occur shortly after 18 GPa and then decompose into NaF and MgF$_2$ above 40 GPa. Phonon dispersions and elastic moduli of the post-perovskite phase confirm its vibrational/mechanical stability. The existence of a post-perovskite transition at low pressures in this material makes possible experimental studies of this uncommon structure in a more easily accessible pressure range. Research supported by NSF/EAR 013533 (COMPRES), 0230319, and NSF/ITR 0428774 (VLab).

–

Authors

  • John Parise

    • Department of Earth and Space Science, SUNY-Stony Brook, NY 11794-2100, USA

  • Koichiro Umemoto

  • Renata Wentzcovitch

    • Department of Chemical Engineering and Materials Science and Minnesota Supercomputing Institute, Univesity of Minnesota
    • Department of Chemical Engineering and Materials Science and Minnesota Supercomputing Institute, University of Minnesota
    • University of Minnesota

  • Donald Weidner

    • Department of Earth and Space Science, SUNY-Stony Brook, NY 11794-2100, USA