期刊
PHYSICAL REVIEW LETTERS
卷 110, 期 13, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.110.135504
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资金
- Lawrence Livermore National Laboratory (LLNL)
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Killam Trusts
- U.S. Department of Energy [DE-AC52-07NA27344]
The phase diagrams of MgSiO3 and MgO are studied from first-principles theory for pressures and temperatures up to 600 GPa and 20 000 K. Through the evaluation of finite-temperature Gibbs free energies, using density-functional theory within the generalized gradient approximation as well as with hybrid exchange-correlation functionals, we find evidence for a vast pressure-temperature regime where molten MgSiO3 decomposes into liquid SiO2 and solid MgO, with a volume change of approximately 1.2%. The demixing transition is driven by the crystallization of MgO-the reaction only occurs below the high-pressure MgO melting curve. The predicted transition pressure at 10 000 K is in close proximity to an anomaly reported in recent laser-driven shock experiments of MgSiO3. We also present new results for the high-pressure melting curve of MgO and its B1-B2 solid phase transition, with a triple point at 364 GPa and 12 000 K. DOI: 10.1103/PhysRevLett.110.135504
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