A theoretical point defect model was proposed for the transition between 2 equilibrium states. Material constants were chosen for La-doped SrTiO3; which served as a model for donor-doped perovskites. A finite-difference method was used to compute the time-dependent evolution of defect concentrations following an excitation of the system. In order to calculate the particle fluxes of all of the charged defects, the time-variant surface concentrations of all mobile species were considered via local defect equilibria. As the surface concentrations differed appreciably from the new equilibrium values, a marked change was expected in the electrical properties of the near-surface region. This new approach was strongly supported by the resistivity changes which occurred during oxidation. A comparison of simulated and experimental data confirmed the applicability of the model.

Advances in Point Defect Chemistry - Space Charge Controlled Surface Reactions. R.Meyer, R.Waser: Journal of the European Ceramic Society, 2001, 21[10-11], 1743-7