Phonon dispersion relation, high-pressure phase stability, and thermal expansion in YVO4

R. Mittal, M. K. Gupta, Baltej Singh, L. Pintschovius, Yu D. Zavartsev, and S. L. Chaplot
Phys. Rev. Materials 3, 043608 – Published 26 April 2019

Abstract

The orthovanadates are useful as host matrices for immobilization of radioactive wastes. The thermodynamic stability of these materials is crucial for their applications in high-pressure and high-temperature environment. It is necessary to investigate the phonons in the entire Brillouin zone, beyond the zone-center phonons accessible in previous Raman and infrared experiments. We have carried out extensive neutron inelastic scattering experiments to derive the phonon dispersion relation of YVO4 up to high-energy transfer of 65 meV using a single crystal, which are perhaps reported for the first time in any orthovanadate compound. The measured phonon dispersion relation is in good agreement with our first-principles density functional theory as well as shell-model calculations. The calculated pressure dependence of phonon modes in the zircon and scheelite phases shows unstable modes and violation of the Born stability criteria at high pressure, which may be lead to instability in YVO4 at high pressures. We also calculate large anisotropy in the thermal expansion behavior, which arises from difference in anisotropic elasticity and mode Grüneisen parameters.

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  • Received 21 February 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.043608

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

R. Mittal1,2, M. K. Gupta1, Baltej Singh1,2, L. Pintschovius3,4, Yu D. Zavartsev5, and S. L. Chaplot1,2

  • 1Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
  • 2Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
  • 3Institute for Solid State Physics, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
  • 4Laboratoire Leon Brillouin, CEA-Saclay, F-91191 Gif sur Yvette Cedex, France
  • 5Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991, Russia

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Issue

Vol. 3, Iss. 4 — April 2019

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