Equation of state and thermal expansivity of NaCl under high pressure and high temperature

In the present study we have used the Vinet–Rydberg EOS for estimating the values of pressure P, isothermal bulk modulus K and its pressure derivative K′ as a function of compression V/V0 for NaCl at room temperature and also at higher temperatures up to 1050 K which is close to the melting temperature of NaCl. Values of thermal expansivity α at different compressions and along different isotherms are also obtained using the Anderson–Isaak and the Chopelas–Boehler approximations. The variations of the product αK with volume along different isotherms are found to exhibit a minimum at a particular combination of pressure and temperature. This prediction is found to be a consequence of the thermodynamic identity for the volume derivative of the product αK.