Ionic conductivity of potassium chloride

An analysis of new measurements of the ionic conductivity of nominally pure KCl, KCl:Sr²⁺, and KCl:SO₄^2?, has shown that a consistent set of defect parameters can be obtained only if KCl contains Frenkel defects on both sub-lattices in addition to Schottky defects. This set of parameters is not unique in the sense that several of the parameters are defined by ranges rather than by specific values. This means that the fit of the experimental conductivity to the theoretical equations for the above model is not significantly worse if these parameters are given any value in the specified range. This set of parameters was then used to calculate the diffusion coefficients of K⁺in KCl, KCl:Sr²⁺ and KCl:SO₄^2?;of Cl^? in KCl and KCl:Sr²⁺; and of SO₄^2? in KCl:SO₄^2?. These calculations enabled the defect parameters to be refined to a unique set, with the exception of the entropy of formation of a Schottky defect, which is shown to lie between 7.5 and 7.9 K.