MASS-TRANSPORT IN THE PRESENCE OF INTERNAL DEFECT REACTIONS - CONCEPT OF CONSERVATIVE ENSEMBLES .4. TRACER DIFFUSION AND INTERCORRELATION WITH CHEMICAL DIFFUSION AND ION CONDUCTIVITY

The tracer diffusion coefficient is analyzed for the case in which internal ionization equilibria have to be considered, using the concept of conservative ensembles. The relationships of the tracer diffusion coefficient with other phenomenological parameters, viz., the chemical diffusion coefficient and the diffusion coefficient derived from the ionic conductivity, as well as with the defect diffusivities are given. The importance of mobile partially ionized or neutral defects is highlighted. In this respect the formulation of the tracer diffusion as an ambipolar diffusion of the different isotopes is helpful.