MASS-TRANSPORT IN THE PRESENCE OF INTERNAL DEFECT REACTIONS - CONCEPT OF CONSERVATIVE ENSEMBLES .1. CHEMICAL DIFFUSION IN PURE COMPOUNDS

Chemical diffusion is considered for the case in which the diffusing species take part in internal defect chemical reactions giving rise to nonvanishing source terms. As long as local equilibrium is maintained, the concept of conservative ensembles allows one to derive generalized expressions for such cases, e.g., when ionic defect states can change their redox state (variable ionization degrees). In the same way the formulation of boundary conditions is analyzed.