Cation Diffusion and Demixing in Yttria Stabilized Zirconia: Comparison of Assumptions of Constant Electric Field and Constant Current

In this paper, the phenomenon of steady-state cation demixing in yttria-stabilized zirconia in an electric field is examined for the case of an open system wherein the defects are everywhere close to internal surfaces which allow the Schottky-defect reaction to occur (very fine grain material). The effect of the constant electric field assumption as a substitute for the constant current condition is analyzed for diffusion by vacancy-pairs and by vacancy-triplets over a wide range of applied electric fields. It is shown that the assumption of a constant electric field provides only a moderate correction to the shape of the demixing concentration profile.