Dissociation of MgSiO3 in the cores of gas giants and terrestrial exoplanets.
CaIrO3-type MgSiO3 is the planet-forming silicate stable at pressures and temperatures beyond those of Earth's core-mantle boundary. First-principles quasiharmonic free-energy computations show that this mineral should dissociate into CsCl-type MgO cotunnite-type SiO2 at pressures and temperatures expected to occur in the cores of the gas giants + and in terrestrial exoplanets. At approximately 10 megabars and approximately 10,000 kelvin, cotunnite-type SiO2 should have thermally activated electron carriers and thus electrical conductivity close to metallic values. Electrons will give a large contribution to thermal conductivity, and electronic damping will suppress radiative heat transport.
Umemoto
Koichiro
K
Department of Chemical Engineering and Materials Science and Minnesota Supercomputing Institute, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA.
Wentzcovitch
Renata M
RM
Allen
Philip B
PB