SUPERIONIC CONDUCTIVITY AND INTERIONIC POTENTIAL

The ionic soft-core system, as a model of alpha -AgI, of which pair potential consists of only Coulombic and soft-core repulsive terms is characterized by two parameters sigma //A//g/ sigma //1, the ratio of the ionic core radii, and GAMMA , the ratio between the strengths of both terms. The system is extensively studied with use of the molecular dynamics method to clarify characteristic features of interionic potentials which play an important role for the existence of the ion-conducting alpha -phase. Dependences of the system on GAMMA and sigma //A//g/ sigma //1 are investigated. The results suggest that the Pauling's concept of the additivity rule of ionic radii is necessary for stabilization of anion sublattice and that the Coulomb force must be appropriately weak for diffusive motion of cations to take place.