Polymorphic Phase Transition in a Potassium Chloride Crystal

Abstract

AbstractThe phase transition data at 298 °K of potassium chloride crystals are analysed on the basis of two alternative models, (a) the Tosi‐Fumi prescription (TFP) in which overlap parameters are taken to be different in the two phases and (b) the three‐body potential model (TBPM) used by Sarkar and Sengupta [1]. The effect of finite temperature and that of zero point energy is included using the Einstein approximation. It is found that the transition data are well reproduced in both the models with TFP giving slightly better values. The temperature coefficient of transition pressure comes out with the right sign but has too high a magnitude in both the models. In elastic data, however, TFP gives poor agreement while for TBPM the agreement is much better.