RANDOM PSEUDOBINARY IONIC ALLOYS - LATTICE ENERGY AND STRUCTURAL-PROPERTIES

Experimental data suggest that in ionic solid solutions the bond-lengt h mismatch is partially accommodated by microscopic lattice distortion s. In this paper we study the structural properties of ionic alloys us ing a generalized Born-Mayer energy model accounting for the possibili ty of atomic-scale relaxations. Cubic supercells are used to simulate the real random alloys, providing statistical information about the at omic distribution and interatomic distances. The good agreement with t he available experimental data and with the results of ab initio pseud opotential calculations performed for comparison for some selected sys tems indicate the validity of the model here employed. We also discuss the applicability to ionic alloys of the special quasi-random structu res originally proposed for semiconducting alloys.