Two-stage dissociation in MgSiO3 post-perovskite

Koichiro Umemoto, Renata M. Wentzcovitch

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

The fate of MgSiO3 post-perovskite under TPa pressures is key information for understanding and modeling interiors of super-Earths-type exoplanets and solar giants' cores. Here, we report a dissociation of MgSiO3 post-perovskite into CsCl-type MgO and P21/c-type MgSi2O5 at ~0.9TPa obtained by first principles calculations. P21/c-type MgSi2O5 should dissociate further into CsCl-type MgO and Fe2P-type SiO2 at ~2.1TPa. The first dissociation should occur in all solar giants and heavy super-Earths, while the second one should occur only in Jupiter and larger exoplanets. Both dissociations are endothermic and have large negative Clapeyron slopes. If the first dissociation should occur in the middle of a silicate mantle, it could promote mantle layering. We provide essential thermodynamic properties of P21/c-type MgSi2O5 for modeling interiors of super-Earths.

Original languageEnglish (US)
Pages (from-to)225-229
Number of pages5
JournalEarth and Planetary Science Letters
Volume311
Issue number3-4
DOIs
StatePublished - Nov 15 2011

Keywords

  • 10 solar giants
  • First principles
  • Postperovskite
  • Pressure-induced phase transition
  • Super-Earth

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