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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.

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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