Stress-induced diffusion and defect chemistry of La0.2Sr0.8Fe0.8Cr0.2O3−δ: Part 3. Defect-chemistry-based modeling

A model based on defect chemistry has been developed to describe the creep behavior of La0.2Sr0.8Fe0.8Cr0.2O3−δ. The model is based on partial clustering of divalent B site cations and oxygen vacancies. According to the model, the increased strain rates at low pO2 are due to increased mobility of B site cations in linked clusters. The cluster concentration is proportional to the oxygen partial pressure, pO2m with m=−1/2 in accordance with the creep data. The model describes the creep behavior in the entire pO2 range used in the measurements. Models based on random non-interacting defects or including ambipolar diffusion, strontium segregation or partial decomposition cannot give the observed pO2 dependence of the creep behavior.