Ionic Conductivity of Potassium Chloride Crystals

Abstract

The ionic conductivity of four relatively pure crystals of potassium chloride has been measured over a wide temperature range. Precautions were taken to minimize the effects of sublimation at temperatures close to the melting point. The data have been analyzed in terms of the conventional Schottky defect model allowing for transport on both sublattices and for both nearest-neighbor and long-range (Debye-H\"uckel) defect interactions. The defect parameters obtained are used to predict cation and anion diffusion coefficients. The cation diffusion coefficients are in excellent agreement with experiment, but both the enthalpy and entropy of activation for anion diffusion are higher than the values obtained from diffusion experiments by Fuller. Possible reasons for these discrepancies are discussed.