Melting curve of SiO2 at multimegabar pressures: implications for gas giants and super-Earths.

ABSTRACT: Ultrahigh-pressure phase boundary between solid and liquid SiO2 is still quite unclear. Here we present predictions of silica melting curve for the multimegabar pressure regime, as obtained from first principles molecular dynamics simulations. We calculate the melting temperatures from three high pressure phases of silica (pyrite-, cotunnite-, and Fe2P-type SiO2) at different pressures using the Z method. The computed melting curve is found to rise abruptly around 330 GPa, an increase not previously reported by any melting simulations. This is in close agreement with recent experiments reporting the α-PbO2-pyrite transition around this pressure. The predicted phase diagram indicates that silica could be one of the dominant components of the rocky cores of gas giants, as it remains solid at

SUBMITTER: Gonzalez-Cataldo F 

PROVIDER: S-EPMC4876395 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature