CALCULATION OF THE FRENKEL DEFECT FORMATION ENERGY IN SILVER-CHLORIDE

A theoretical study has been made of the defect structure of silver chloride. An interionic potential based on the quasiharmonic model is developed and temperature-dependent Frenkel defect formation energies are calculated using the HADES program. These defect formation energies, when used in conjunction with experimentally determined defect migration and interaction energies, are shown to reproduce the relevant conductivity data from room temperature to the melting point. The activation energy for the migration of Na+ ion impurity in silver chloride has also been calculated and used, together with the theoretical defect concentrations, to calculate diffusion coefficients for the sodium ion. These theoretical diffusion rates are in excellent agreement with the experimental data over the complete temperature range in which the measurements have been made.