Two-stage dissociation in MgSiO3 post-perovskite
نویسندگان
چکیده
a r t i c l e i n f o Keywords: pressure-induced phase transition postperovskite super-Earth 10 solar giants first principles The fate of MgSiO 3 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 MgSiO 3 post-perovskite into CsCl-type MgO and P2 1 /c-type MgSi 2 O 5 at ~0.9 TPa obtained by first principles calculations. P2 1 /c-type MgSi 2 O 5 should dissociate further into CsCl-type MgO and Fe 2 P-type SiO 2 at ~ 2.1 TPa. 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 Cla-peyron 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 P2 1 /c-type MgSi 2 O 5 for modeling interiors of super-Earths.
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