High-temperature equation of state of vanadium

The unit cell dimensions of vanadium, NaCl and Au have been collected to 11. 5 GPa and 1000 K by powder X-ray diffraction and are used to constrain a practical higherature EoS for bcc vanadium. The resulting third-order Birch-Murnaghan EoS is described with parameters K_{T0,300} = 150.4 ± 6.2 GPa, K'_{T} = 5.5 ± 1.0, α0 = 4.8(6)·10^{-5} , α1 =-2.4(9)·10^{-8} and δK'TδT =-0.0446(7) GPa/K. The parameter α.K_{0,300} is 616·10^{-5} K^{-1} GPa and reduces to zero at an estimated 60 GPa at RT. This EoS description is entirely consistent with the majority of X-ray, ultrasonic, shock wave and calculated data-sets in this p, T range. These measurements facilitate the estimation of in situ temperatures under high pressures when vanadium is used inside sample assemblies and are useful, when used with h-BN, to estimate p, T over the full range of h-BN stability.