A case study of mechanical properties of perovskite-structured Ba0.5Sr0.5Co0.8Fe0.2O3−δ oxygen transport membrane

This study has investigated mechanical properties of perovskite-structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) oxygen transport membrane. The Young's modulus and fracture toughness are determined by both macroscopic-scale and microscopic-scale methods. Both three-point and ring-on-ring bending tests as macroscopic-scale methods produce broadly similar results with a Young's modulus, which is lower than that measured from micro-indentation method under a 10 N load. Young's modulus and fracture toughness of BSCF show strongly dependent of the porosity. However, the fracture toughness of BSCF is independent of grain size. The fracture toughness determined by macroscopic-scale method is similar with that measured by microscopic-scale method. The crack shape of BSCF under a 10 N load is determined to be a median-radial mode. The intrinsic Young's modulus and fracture toughness are determined to be 105.6 GPa and 1.49 MPa m0.5, respectively, according the Minimum Solid Area (MSA) model. Annealing decreases the fracture toughness of BSCF between RT and 800 °C.