FP-LAPW calculations of equation of state and elastic properties of αα and ββ phases of tungsten carbide at high pressure

Tungsten carbide is used in high pressure devices therefore knowledge of its elastic properties and their pressure dependence is of utmost practical importance. In this paper we present first principles results of equation of state and elastic properties of αα and ββ phases of tungsten carbide and compare our results with the available reported experimental results. These calculations have been performed using the FPLAPW method within the framework of density functional theory. Enthalpies of αα and ββ phases of WC have been compared up to 350 GPa to investigate possibility of structural transformation. Density-dependent Grüneisen parameter has been deduced from P−VP−V isotherm using the well-known Slater's formula. High pressure elastic constants of αα and ββ phases of WC have been calculated by applying various distortions to the original crystal structure. The elastic properties such as bulk, shear and Young's moduli have been derived from the calculated elastic constants. Pressure-dependent longitudinal velocity, shear velocity, Debye temperature and melting temperature have been deduced from the elastic properties. These calculated properties are in good agreement with the available experimental results.

► Pressure-dependent lattice parameters and Grüneisen coefficient predicted for WC.
► DOS results reveal that the stability of a phase should increase on increasing the pressure.
► Elastic properties Cij, B, G, E  , νν predicted up to 120 GPa for αα and ββ phases of WC.
► The brittleness and anisotropy discussed using G/BG/B, νν and anisotropy constants, respectively.
► Pressure-dependent Debye and melting temperature deduced from elastic properties.