Elastic Constants of Boron Arsenide and Boron Phosphide Crystals

ORAL

Abstract

We report the elastic constants of boron arsenide and boron phosphide single crystals derived from Brillouin frequencies measured by picosecond interferometry. The synthesis of BAs and BP with thermal conductivity as high as 1000 and 540 Wm-1K-1, respectively, has made them into promising materials for thermal management. Accurate measurements of elastic constants are needed to assess the accuracy of computational modeling of the lattice dynamics. The crystals are cut and polished in different orientations to access waves travelling along different directions. The orientations of the surface normals are determined using electron backscattering diffraction. We studied the Brillouin frequencies of quasi longitudinal waves in five orientations each of BAs and BP crystals. The propagation directions and acoustic velocities are used to construct Christoffel equations which are then solved for the elastic constants. We report C11, C12, and C44 values of 291 ± 5 GPa, 76 ± 13 GPa, and 173 ± 6 GPa for BAs and 354 ± 5 GPa, 83 ± 15 GPa, and 190 ± 8 GPa for BP. Furthermore, we also demonstrate the utility of PI in studying optical and acoustic attenuation in these crystals.

*This work is supported by Office of Naval Research (ONR) MURI through grant N00014-16-1-2436.

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Presenters

  • Sushant Mahat

    • Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign

Authors

  • Sushant Mahat

    • Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign

  • Sheng Li

    • Department of Physics, University of Texas at Dallas
    • Physics, The University of Texas at Dallas
    • Department of Physics, The University of Texas at Dallas

  • Hanlin Wu

    • Department of Physics, University of Texas at Dallas
    • Physics, The University of Texas at Dallas
    • Department of Physics, The University of Texas at Dallas

  • Pawan Koirala

    • Department of Physics, University of Texas at Dallas

  • Bing Lv

    • The University of Texas at Dallas
    • Department of Physics, University of Texas at Dallas
    • Physics, The University of Texas at Dallas
    • Department of Physics, The University of Texas at Dallas
    • University of Texas at Dallas

  • David G. Cahill

    • Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign
    • University of Illinois at Urbana-Champaign