High-pressure high-temperature equations of state of shocked bcc vanadium

Abstract

The semiempirical free-energy relation for hydrostatically compressed isotropic solid was written for body-centered-cubic (bcc) vanadium as a function of the specific volume and temperature with the phonon component and the contribution of the electronic subsystem. According to the thermodynamic rules the thermal as well as caloric equations of state are defined through the partial derivatives of free energy. A thermal equation of state gives the pressure as a function of volume and temperature. Caloric equation of state specifies the energy as a function of volume and temperature also. The proposed equations of state of bcc vanadium have been verified by comparison of calculated high-pressure isotherms, heat capacity, volume thermal expansion coefficient and Hugoniot with experimental data. The developed equations of state allow to calculate thermal properties of compressed bcc vanadium under static pressure and shock pressures 0-70 GPa and temperatures 100-1000 K.