Fast ion transport in solids induced by an electric field

A theoretical model is suggested to describe the abrupt transition, induced by an electric field, of a cation sublattice in the ionic crystal bulk, as a result of which the crystal passes into the superionic conductivity state. The concepts which underlie the model are that the Frenkel defect interactions play an essential part in crystal, and the electric field greatly influences the defect formation energy. Expressions for the free energy of disordering, for the interstitial population in the crystal as a function of the strength of the electric field applied and for the critical value of the electric field which induces phase transitions have been obtained in terms of the mean field approximation. The first experimental data on the discovery and analysis of the jump in the ionic conductivity induced by an electric field, described previously, are discussed.