High-pressure behaviors of a niobium nitride single crystal

ORAL

Abstract

We report the measurements of the high-pressure lattice structures, Raman-scattering spectra, and superconducting transition temperatures up to 50 GPa on a non-stoichiometric niobium nitride single crystal. The material remains the simple $B1$ NaCl structure over the whole pressure range with a bulk modulus of 348 GPa, comparable to that of cubic boron nitride. The pressure-induced phonon frequency shifts are obtained based on the Raman-scattering data. These results together with the calculated electronic density of states are used to explain our observed constant superconducting transtion at 12.6 K under pressures in this material.

*Work at Carnegie was supported by the US Department of Energy (DOE) (Grant Nos. DEFG02-02ER4595 and DEFC03-03NA00144) and Office of Naval Research (Grant No. N000140210506).

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Authors

  • Xiao-Jia Chen

  • Viktor V. Struzhkin

  • Zhigang Wu

  • Ronald Cohen

    • Carnegie Institution of Washington
    • Geophysical Laboratory, Carnegie Institution of Washington

  • Ho-kwang Mao

  • Russell Hemley

    • Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015
    • Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd., NW, Washington DC, 20015
    • Geophysical Laboratory, Carnegie Institution of Washington

  • Axel N{\O}rlund Christensen

    • H{\o}jkolvej 7, DK-8210 Aarhus V, Denmark