Single crystal x-ray diffraction, synchrotron infrared spectroscopy, and first-principles calculations of oP32-type Ge under pressure

ORAL

Abstract

Single-crystal diffraction of the oP32-structured allotrope of Ge was performed under hydrostatic and quasihydrostatic pressures up to 6 GPa. Analysis of unit cell parameters, systematic absences, and structure factors show no evidence for structural transitions, as a continuous compression of the structure was observed. In addition, occurrence of multiple domains as well as diffuse scattering rods between Bragg peaks along some directions are observed, which could be the result of stacking disorder. The phase transforms to the β-Sn type structure near 9 GPa, as indicated by powder diffraction which was conducted to at least 32 GPa. Synchrotron infrared and optical absorption measurements up to 8.5 GPa indicate widening of the band gap of the op32 phase prior to collapse to the highly reflecting metallic β-Sn type phase. The increased band gap energy with pressure of oP32 Ge and the phase transition to the b-Sn phase agree with first-principles density functional theory calculations. The effects of pressure on the structural and electronic properties of oP32 Ge will also be discussed.

*This work is supported by US Air Force Office of Scientific Research Grants FA9550-15-1-0236 and FA9550-20-1-0068, the T. I. I. Temple Foundation, the John J. and Rebrcca Moores Endowment, the State of Texas through the Texas Center for Superconductivity at the University of Houston, the U.S. National Science Foundation grant DMR-1933622, and the Chicago/DOE Alliance Center (CDAC) DOE-NNSA cooperative agreement DE-NA0003975. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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Publication: N/A

Presenters

  • Muhetaer Aihaiti

    • University of Illinois Chicago
    • Carnegie Inst of Washington
    • Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
    • University of Illinois at Chicago, USA

Authors

  • Muhetaer Aihaiti

    • University of Illinois Chicago
    • Carnegie Inst of Washington
    • Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
    • University of Illinois at Chicago, USA

  • Barbara Lavina

    • Argonne National Laboratory
    • Advanced Photon Source
    • X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439 USA

  • Zhenxian Liu

    • Department of Physics, University of Illinois at Chicago, Chicago IL 60607, USA

  • Yuki Sakai

    • University of Texas at Austin
    • Center for Computational Materials, Oden Institute of Computational Engineering and Sciences, University of Texas at Austin, Austin, TX 78712, USA

  • Liangzi Deng

    • University of Houston
    • Texas Center for Superconductivity and Department of Physics, University of Houston
    • Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204, USA

  • Zhongjia Tang

    • Texas Center for Superconductivity and Department of Chemistry, University of Houston. Houston, TX 77204, USA

  • Arnold M Guloy

    • Texas Center for Superconductivity and Department of Chemistry, University of Houston, Houston, TX 77204, USA

  • James R Chelikowsky

    • University of Texas at Austin
    • Texas Center for Superconductivity and Department of Chemistry, University of Houston, Houston, TX 77204, USA

  • Marvin L Cohen

    • University of California, Berkeley
    • Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA; Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

  • Ching-Wu W Chu

    • Texas Center for Superconductivity and Department of Physics, University of Houston
    • Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX 77204, USA; Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
    • University of Houston and Lawrence Berkeley National Laboratory

  • Russell J Hemley

    • University of Illinois Chicago
    • University of Illinois at Chicago
    • George Washington Univ
    • Departments of Physics and Chemistry, University of Illinois at Chicago
    • Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA; Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
    • Department of Physics, University of Illinois Chicago, Chicago, USA
    • University of Illinois at Chicago, USA