AbstractAn interrelationship between the pressure derivatives constants and higher‐order elastic constants is investigated. Some useful relations connecting the first‐ and second‐order pressure derivatives of dielectric constants, third‐ and fourth‐order elastic constants, and bulk modulus and its pressure derivatives are obtained. A numerical application of these relations in the case of alkali halide crystals yields results which are found to be in good agreement with available experimental data. The utility of the mathematical expressions reported in the present work is demonstrated by calculating the pressure derivatives of dielectric constants.
AbstractRecently developed interionic potentials are used to evaluate some important thermodynamic quantities and the high‐pressure equation of state of alkali hydride crystals. Values of short range overlap repulsive interactions estimated with the help of overlap integrals along with recent values of van der Waals interactions are used in calculations. Values of the Grüneisen parameter and its volume derivative, the Anderson parameters, volume thermal expansion coefficient, and the Debye temperature are calculated and reported. The high‐pressure equation of state for LiH and NaH are investigated using a detailed picture of the interionic potentials.
AbstractEquation of state and dielectric properties of alkali halides under the effect of high pressure are investigated using the generalized Huggins‐Mayer potential form. Values of potential parameters derived from ultrasonic data and recent van der Waals interactions by taking proper account of thermodynamic contribution are used in the present calculations of the equation of state and the volume derivatives of dielectric constants. It is found that the inclusion of thermodynamic contribution based on recent data improves significantly the agreement between theoretical and experimental results. The present investigation is superior to other previous studies in respect of using a thermodynamically consistent set of potential parameters.
