Thermodynamics of the Soret effect in ionic crystals

Abstract

The phenomenological equations of irreversible thermodynamics have been used to derive an expression for the Soret effect for a substitutional cation impurity in an ionic conducting crystal containing Schottky disorder. The modification of the result is stated when additional cationic Frenkel disorder occurs, and also the result when the impurity is interstitially incorporated. Suitable systems for measurements are noted. The relationship to the theory of Howard, which assumed zero anion diffusion and used no cross phenomenological coefficients between matter fluxes, is indicated.