Thermal Expansion and Compression of Alkaline Earth Oxides and Cesium Halides at High Temperature and High Pressure

Abstract

Temperature and pressure dependence of thermal expansion and compression of alkaline earth oxides and cesium halides with NaCI-and CsC1-type structures is investigated. The theory of interionic potentials based on the quantum mechanical form of the overlap repulsive energy is used to investigate the interatomic separations as a function of temperature and pressure from room temperature up to the melting temperature and from zero pressure up to the structural transition pressure. The values of van der Waals dipole--dipole and dipole-quadrupole energies are also included in the model. The results are used to predict the temperature and pressure dependence of the coefficient of volume thermal expansion using a formula derived on the basis of the thermodynamic analysis. The results are compared with available experimental data and discussed in the light of recent research.

Pressure Dependence of Interatomic Separation and Thermal Expansivity for Alkali Halides and Periclase (MgO)

“…The experimental data for the α vs. P are available only for NaCl [12] in the range of small compressions 0.9 < η < 1. For convenience of comparison, the result given by Upadhyay and Kumar [17,18] with Eq. (7) is also listed together with our calculated results.…”