Superionic Conductivity and Interionic Potential

The ionic soft-core system, as a model of α-AgI, of which pair potential consists of only Coulombic and soft-core repulsive terms is characterized by two parameters σ Ag /σ I , the ratio of the ionic core radii, and Γ, the ratio between the strengths of the 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 α-phase. Dependences of the system on Γ and σ Ag /σ I are investigated. Our 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.