An equation of state for molybdenum and tungsten

An equation of state (EOS) recently formulated by Shanker and Kushwah has been used for calculating the volumes of molybdenum (Mo) and tungsten (W) at simultaneously elevated pressures and temperatures. The results are obtained up to a pressure of 300 GPa and up to a temperature of nearly 7000 K. The values of thermal pressure have been calculated using the formulation given by Anderson and Isaak which takes into account the effect of thermal excitation of electrons. The Shanker–Kushwah EOS has been found most suitable for the materials for which the pressure derivative of isothermal bulk modulus at P=0, i.e. K 0′ is less than four. The solids Mo and W satisfy this condition. The values of volumes and isothermal bulk modulus calculated at different temperatures and pressures are found to present close agreement with the experimental data based on shock wave measurements reinforcing the validity of the equation of state used. The results based on the Shanker–Kushwah EOS are found to compare well with the corresponding values derived from the Vinet EOS.