Oxygen permeation and microstructure of intergrowth perovskite Sr-La-Fe-Co based mixed-conductive ceramics

The partial oxidation reforming method is advantageous to develop highly effective and low-cost products of H2 gas used for fuel cells. For the partial oxidation, however, large amount of pure O2 gas are desirable for acceleration of the H2 production. Electronic and oxygen ionic conductive (mixed-conductive) oxide ceramics can be used to obtain pure O2 gas, because the mixed conductivity contributes to permeate pure O2 gas from air at the elevated temperatures. However, high permeation temperature of above 900°C is a problem. Higher temperature for the permeation incurs deterioration of both the ceramics and the steel to support the ceramics. We intend to find out a new mixed-conductive oxide with high oxygen permeation at lower temperatures than 900°C. In this study, we focus the Sr-La-Fe-Co oxides characterized by the intergrowth structures. We have investigated an appropriate condition to prepare Sr3-xLaxFeCoO7-δ ceramics with intergrowth perovskite structure. Then we have investigated microstructures as well as oxygen permeation properties of a dense Sr2.45La0.55FeCoO7-δ ceramics. The oxygen permeation flux of the Sr2.45La0.55FeCoO7-δ ceramics was as high as that of cubic perovskite Sr0.8La0.2 Fe0.8Ga0.2O3-δceramics