期刊
PHYSICAL REVIEW B
卷 83, 期 18, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.83.184102
关键词
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资金
- US Department of Energy, Basic Energy Sciences, Division of Materials Science and Engineering [DE-AC02-07CH11358]
- NSF [EAR-0757903, EAR-0810272, EAR-1047629, ATM-0426757]
- Division Of Earth Sciences
- Directorate For Geosciences [1019853] Funding Source: National Science Foundation
- Division Of Earth Sciences
- Directorate For Geosciences [0810272] Funding Source: National Science Foundation
Using a first-principles genetic algorithm we predict an Fe2P phase is the first post-pyrite phase of SiO2 at low temperatures. This contrasts with a recently predicted cotunnite phase. Static enthalpy differences between these two phases are small near the transition pressure (0.69 TPa). While quasiharmonic free energy calculations predict an Fe2P--> cotunnite-type transition with increasing temperature, another phase, NbCoB type, is identified as being structurally and energetically intermediate between Fe2P and cotunnite phases. This structure suggests a possible temperature-induced gradual transformation between Fe2P and cotunnite phases. This finding would change our understanding of how planet-forming silicates, for example, MgSiO3 post-perovskite and its solid solutions, dissociate into elementary oxides at thermodynamic conditions expected in the interior of solar giants and exoplanets.
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