Thermal Diffusion in Crystalline Binary Compounds with Narrow Range of Homogeneity – I. A New Experiment for the Determination of the Heat of Transport

Abstract

AbstractThe formal analysis of the coupling between diffusional matter and heat transport shows that diffusional matter fluxes are driven by both temperature and composition gradients, and that matter fluxes are always connected with heat fluxes. An important concept in the description of this coupling is the introduction of so‐called heats of transport. The heats of transport, being combinations of phenomenological transport coefficients, denote the relation between individual matter fluxes and related heat fluxes for isothermal systems. For the case of mixed ionic/electronic conducting binary compounds with narrow ranges of homogeneity, A1+δXV, a new experiment for the determination of the reduced heat of transport of metal A is proposed and discussed with respect to a possible realization. The experiment is based on the direct measurement of the flux of the metal component in a temperature gradient, under special boundary conditions for the composition of the sample, and gives direct access to the (reduced) heat of transport, Q*A. Alternative ways for the determination of the heat of transport are summarized and compared with the proposed experiment.