Stresses due to oxygen potential gradients in non-stoichiometric oxides

We present a new continuum model for the evolution of stresses developed due to the non-stoichiometry of ceramic oxides. The model self-consistently accounts for the diffusion of all components, interfacial oxidation/reaction kinetics and the effect of stress on transport through the oxide layer. This model is employed to predict stress evolution in gadolinia doped ceria electrolyte-based fuel cells. Numerical solution of the model shows that the relative rates of interfacial reaction and oxygen diffusion in the oxide critically determine both the variation of stress across the thickness of the oxide film and its evolution. Calculated results, in agreement with experimental observations, show that doped ceria electrolyte-based fuel cells are safe to operate at temperatures less than 700 °C. The dopant content in the electrolyte and the specific configuration of the fuel cell are also found to significantly influence stress evolution in the electrolyte layer.