The curvature in conductivity plots of silver halides as a consequence of anharmonicity

Abstract By assuming that the creation of a vacancy is accompanied by a local dilatation, the free energy of formation has been determined. Taking the thermal expansivity into account, the corresponding formation enthalpy and entropy were found to be temperature dependent. The same holds for migration enthalpy and entropy. It is shown that this temperature dependence of the above quantities must be partially responsible for the curvature in the conductivity plot of alkali, and silver, halides which has been experimentally observed. For KCl a conductivity deviation of 12% could be attributed to the above effect.

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