Elastic constants and volume changes associated with two high-pressure rhombohedral phase transformations in vanadium

Abstract

We present results from ab initio calculations of the mechanical properties of the rhombohedral phase (beta) of vanadium metal reported in recent experiments, and other predicted high-pressure phases (gamma and bcc), focusing on properties relevant to dynamic experiments. We find that the volume change associated with these transitions is small: no more than 0.15% (for beta - gamma). Calculations of the single crystal and polycrystal elastic moduli (stress-strain coefficients) reveal a remarkably small discontinuity in the shear modulus and other elastic properties across the phase transitions even at zero temperature where the transitions are first order.