Prediction of crystal structures and motifs in the Fe-Mg-O system at Earth's core pressures

被引:1
作者
Wang, Renhai [1 ,2 ,3 ]
Sun, Yang [4 ]
Wentzcovitch, Renata [4 ,5 ,6 ]
Zheng, Feng [7 ]
Fang, Yimei [7 ]
Wu, Shunqing [7 ]
Lin, Zijing [3 ]
Wang, Cai-Zhuang [2 ]
Ho, Kai-Ming [2 ]
机构
[1] Guangdong Univ Technol, Sch Phys & Optoelect Engn, Guangzhou 510006, Peoples R China
[2] Iowa State Univ, Dept Phys, Ames, IA 50011 USA
[3] Univ Sci & Technol China, Dept Phys, Hefei 230026, Peoples R China
[4] Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA
[5] Columbia Univ, Dept Earth & Environm Sci, New York, NY 10027 USA
[6] Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA
[7] Xiamen Univ, Dept Phys, Xiamen 361005, Peoples R China
来源
NEW JOURNAL OF PHYSICS | 2021年 / 23卷 / 06期
基金
中国国家自然科学基金; 美国国家科学基金会;
关键词
FeMgO; crystal structure prediction; high pressure; first-principles calculation; TOTAL-ENERGY CALCULATIONS; EFFECTIVE POTENTIALS; PHASE-TRANSITION; X-RAY; IRON; OXYGEN; TEMPERATURE; MANTLE; MGFE2O4; METALS;
D O I
10.1088/1367-2630/ac0287
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
Fe, Mg, and O are among the most abundant elements in terrestrial planets. While the behavior of the Fe-O, Mg-O, and Fe-Mg binary systems under pressure have been investigated, there are still very few studies of the Fe-Mg-O ternary system at relevant Earth's core and super-Earth's mantle pressures. Here, we use the adaptive genetic algorithm (AGA) to study ternary Fe Mg-x(y) O-z phases in a wide range of stoichiometries at 200 GPa and 350 GPa. We discovered three dynamically stable phases with stoichiometries FeMg2O4, Fe2MgO4, and FeMg3O4 with lower enthalpy than any known combination of Fe-Mg-O high-pressure compounds at 350 GPa. With the discovery of these phases, we construct the Fe-Mg-O ternary convex hull. We further clarify the composition- and pressure-dependence of structural motifs with the analysis of the AGA-found stable and metastable structures. Analysis of binary and ternary stable phases suggest that O, Mg, or both could stabilize a BCC iron alloy at inner core pressures.
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页数:12
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