Ferroelasticity and hysteresis in LaCoO3 based perovskites

Perovskite-type ABO₃ (where A=La, Ca; B=Co) ceramics are very promising materials for oxygen separation membrane and solid oxide fuel cells applications. However, their mechanical behavior has not yet been adequately studied. We studied the mechanical performance of perovskite ceramics using a combination of microindentation, compression, and bending. Our work demonstrated ferroelastic hysteretic behavior during indentation and compression loading in LaCoO₃ based perovskites. This behavior can be caused by domain reorientation and/or phase transformation. Domain switching under the compression loading in LaCoO₃ based perovskites has been demonstrated by XRD. Nonlinearity during fracture toughness measurements was observed in the dense La_0.8Ca_0.2CoO₃ perovskite. Such nonlinearity can be assigned to the domain switching or the phase transformation during crack propagation. This might be a reason of a higher fracture toughness of this material compared to non-ferroelastic composition.