Atomic-scale structure of alkali halide solid solutions

A simple model is proposed to explain the crystallographic properties of solid solutions of the alkali halides. The random system is simulated with a periodic superlattice whose energy is evaluated with the Born-Mayer model generalized to include ionic polarization. The resulting average lattice parameter and anioncation distances agree with recent EXAFS data on K1 12xRbxBr, RbBr1 12xIx, and KCl1 12xBrx. The results show that ionic polarization plays a significant role in the determination of both interatomic distances and heats of formation