COUPLING BETWEEN ELECTRON AND ION-TRANSPORT IN MIXED CONDUCTORS

A quantitative model is presented for the coupling between electron and ion transport in mixed conductors. Phenomenological transport coefficients, as measured in a symmetrical cell with both, ionic and electronic probes, on a mixed conducting solid, are expressed in terms of partial conductivities of electronic and ionic defects. Within this model, non-zero coupling coefficients arise from trapping of electrons on mobile ionic defects and corresponding ionization equilibria, as well as from differences in charge numbers of mobile ions between sample and ionic probes. The formulation of ionic and electronic current densities as well as the matrix of phenomenological coefficients depends on the selected ionic probes as well as on the types of mobile ionic and electronic defects in the sample. © 1990.