Thermoelastic properties of alkali halides at high temperatures

The thermoelastic properties of materials at high temperatures, specifically the thermal expansivity and the isothermal bulk modulus have been studied using the Anderson formula for thermal expansivity and the interatomic potential functions within the framework of the Born model. We have considered sixteen alkali halides with NaCl structure, and calculated their properties for a wide range of temperatures starting from room temperature up to their melting temperatures. Potential energy curves have been plotted and used to determine interatomic distances at the melting points. The results for interatomic distances, thermal expansivity and isothermal bulk modulus at different temperatures have been found to compare well with the available experimental data. The Hildebrand equation of state has been used to predict the pressure-volume-temperature relationship in case of NaCl using the Born-Mayer exponential potential function. The results,thus, obtained are found to present good agreement with the measured data.