Defect formation and mechanical stability of perovskites based on LaCrO3 for solid oxide fuel cells (SOFC)

Different perovskite compositions made of (La,Ca/Sr)CrO3-delta, La(Cr,Mg)O3-delta, La(Cr,Mg/Cu/Co,Al)O3-delta, and (La,Ca)(Cr,Al)O3-delta were investigated. Defect models were evaluated to describe the oxygen vacancy formation and the respective thermodynamic data were determined. The results are used to explain existing literature data on the isothermal expansion of LaCrO3 based perovskites under reducing conditions. Complementary mechanical measurements with selected perovskite compositions revealed that lower oxygen partial pressure causes higher stiffness, strength and fracture toughness. The change in properties is discussed in terms of the observed ferroelastic domains and the interaction of the domain wall motion with the oxygen vacancies. 30 refs.