Theoretical Treatment of the Diffusion Coupled with Reaction, Applied to the Example of a Binary Solid Compound MX

Abstract

AbstractIt is shown, that the coupling of diffusion processes with reactions can be treated as a formal ambipolar diffusion of ensembles of particles, which are conserved in the reaction scheme. In this way an extension of the flow equations to a complex defect chemistry becomes possible, as exemplified by the ionization processes of the ionic point defects in a binary solid MX. In a first approximation Fick's laws with generalized diffusion coefficients are obtained. The boundary conditions are formulated for several important cases by considering the equations of balance of the conservative ensembles. It is further shown, how the new evaluation of the usual electrochemical measurements of transport quantities (e.m.f., polarization and permeation) has to be performed. Additional terms, caused by the ionization processes, appear in all evaluation formula.