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.

*This work was funded by National Science Foundation Award No. EAR-1918126 and EAR-1918134.

–

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