Oxygen permeation properties of mixed conductive Sm0.5Ca0.5FeO3

Abstract To investigate influence of Ca doping on oxygen permeation properties in orthorhombic perovskite (Sm, Ca)FeO 3 series, we investigated the oxygen permeation flux ( J O2 ), electrical conductivity and crystal structure of Sm 1 −  x Ca x FeO 3 ( x  = 0.5). Then we compared the investigated results with those of the other compositions: x  = 0.2, 0.25 and 0.3. The J O2 increased and the activation energy E J of J O2 decreased with increases of the Ca content from x  = 0.2 to 0.5. The Sm 1 −  x Ca x FeO 3 ( x  = 0.2–0.5) showed no remarkable difference in total electrical conductivity at temperatures higher than 800 °C, meaning that no significant influence of the electrical conductivity on the J O2 . The lattice distortion relating to the FeO 6 tilt relaxed with the Ca doping. The bottleneck size for ion migration decreased with the Ca doping. The results suggest the relaxation of lattice distortion is a main factor to make ion migration easier and then improve the J O2 .