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

ORAL

Abstract

While the crystal structures of Fe-O and Fe-Mg binary systems under pressure have been extensively studied recently, there are still very few studies of the Fe-Mg-O ternary phases at relevant Earth’s core and super-Earth’s mantle pressures. Here, we use the adaptive genetic algorithms (AGA) to search for and study the crystal structure of FexMgyOz phases in a wide range of stoichiometries at 200 GPa and 350 GPa. Our results revealed new phases with lower enthalpy than the known compounds in the existing Fe-Mg-O high-pressure structure database. By constructing the convex hull at both pressures, we determine the ground-state phases. We also carry out structure motif analyses for AGA-found stable and metastable structures. We find a wide variety of composition- and pressure-dependent motifs.

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Presenters

  • Renhai Wang

    University of Science and Technology of China, Department of Physics, Department of Physics, University of Science and Technology of China, Iowa State University

Authors

  • Renhai Wang

    University of Science and Technology of China, Department of Physics, Department of Physics, University of Science and Technology of China, Iowa State University

  • Yang Sun

    Columbia University

  • Feng Zheng

    Department of Physics, Xiamen University

  • Yimei Fang

    Department of Physics, Xiamen Univ, Department of Physics, Xiamen University

  • Feng Zhang

    Ames Laboratory, Department of Physics, Iowa State University, Iowa State University

  • Shunqing Wu

    Department of Physics, Xiamen Univ, Department of Physics, Xiamen University

  • Zijing Lin

    Department of Physics, University of Science and Technology of China

  • Cai-Zhuang Wang

    Ames Laboratory, U.S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Iowa State University, Dept. of Physics and Astronomy, Iowa State University, Ames Laboratory and Iowa State University, Department of Physics, Iowa State University

  • Renata M Wentzcovitch

    Columbia Univ, Department of Applied Physics and Applied Mathematics, Columbia University, Applied Physics and Applied Mathematics, Columbia University, Columbia University

  • Kai-Ming Ho

    Ames Laboratory, U.S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Iowa State University/AmesLab, Ames Laboratory and Iowa State University, Department of Physics, Iowa State University, Iowa State University