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Science 17 February 2006:
Vol. 311. no. 5763, pp. 983 - 986
DOI: 10.1126/science.1120865
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Reports

Dissociation of MgSiO3 in the Cores of Gas Giants and Terrestrial Exoplanets

Koichiro Umemoto,1 Renata M. Wentzcovitch,1* Philip B. Allen2

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 ~10 megabars and ~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.

1 Department of Chemical Engineering and Materials Science and Minnesota Supercomputing Institute, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455, USA.
2 Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794–3800, USA.

* To whom correspondence should be addressed. E-mail: wentzcov{at}cems.umn.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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