Creep behavior of porous La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen transport membrane supports

Advanced oxygen transport membrane designs rely upon a thin functional layer supported by a porous substrate material that carries the mechanical loads. The creep deformation behavior needs to be assessed in order to warrant a long-term reliable operation at elevated temperatures. The current study reports the creep behavior of porous La0.6Sr0.4Co0.2Fe0.8O3−δ in air for a temperature range of 750-950 °C. Stress exponents and activation energies are derived from the deformation data. A comparison with the creep rates of dense material revealed a progressively increasing creep rate with increasing temperature that might be related to surface diffusional effects. Additional tests at room temperature revealed non-linear stress-strain curves and an apparent ferroelastic creep due to domain switching in the rhombohedral phase that is stable at lower temperature.