Pm3m-Fm3m transformations of alkali halides. Solid solutions of CsCl with KCl, CsBr, SrCl<SUB>2</SUB>

Pm3m-Fm3m transformations of solid solutions of CsCl with KCl and CsBr exhibit different behaviours. With increasing percentages of KCl, the NaCl structure gets stabilized in the CsCl+KCl system. In the CsCl+CsBr system, the transformation temperature increases with % CsBr and ΔH essentially remains constant. Both these behaviours can be satisfactorily explained in terms of the Born treatment of ionic solids. The Pm3m-Fm3m transformation retains its first-order characteristics in the CsCl+KCl system, but higher-order components seem to be present in the CsCl+CsBr system. Incorporation of vacancies do not affect the transformation of CsCl markedly