González-Cataldo F, Davis S, Gutiérrez G. Melting curve of SiO2 at multimegabar pressures: implications for gas giants and super-Earths.
Sci Rep 2016;
6:26537. [PMID:
27210813 PMCID:
PMC4876395 DOI:
10.1038/srep26537]
[Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 04/22/2016] [Indexed: 11/24/2022] Open
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 the core of our Solar System’s gas giants. These results are also relevant to model the interior structure and evolution of massive super-Earths.
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