The compressive creep behavior of La0.2Sr0.8Fe0.8Cr0.2O3-δ in an O-controlled atmosphere was investigated. The creep behavior was investigated for stress, temperature and grain sizes of 10 to 80MPa, 1100 to 1175C and 3.2 to 28.5μm. The O atmosphere was controlled to have an O partial pressure range of PO2 = 0.21 to 10-14atm. The material exhibited 2 markedly different behaviors at high and low PO2. At high PO2, the behavior was characterized by the O partial pressure exponent, m, of 0.04, followed by a sharp increase in strain rates at low PO2, characterized by m = -0.5. In the m = -0.5 regime, the effect of O partial pressure upon the grain size exponent, as well as the transition to power-law creep was investigated. It was concluded that the mechanism responsible for the rapid increase in strain rates increases the contribution of bulk diffusion from predominant (p = 2.3) to nearly pure bulk diffusion (m = 2.07). The same mechanism also increases the stress range for predominant diffusion creep relative to power-law creep.

Stress-Induced Diffusion and Defect Chemistry of La0.2Sr0.8Fe0.8Cr0.2O3-δ - Creep in Controlled-Oxygen Atmosphere. G.Majkic, L.T.Wheeler, K.Salama: Solid State Ionics, 2003, 164[3-4], 137-48