Analysis of high pressure equations of state for sodium halides

An analysis of high pressure equations of state has been performed to deter mine the pressure-volume relationships for NaF, NaCl, NaBr and Nal crystals under pressures up to their phase transition pressures. The results have b een obtained using five different phenomenological forms of isothermal equa tion of state. It has been found that the results obtained from the usual T ait equation, the Brennan-Stacey equation, the Vinet universal equation and the Shanker equation are in good agreement with the experimental data for the solids under study. The Murnaghan's equation has been found to yield si gnificantly large deviations from experimental data. Modifications suggeste d recently to remove the shortcomings of the Murnaghan's equation have been discussed. Values of isothermal bulk modules K-T, pressure derivative of K -T' and the Gruneisen parameter have also been calculated for NaCl under hi gh compressions.