Oxide Ion Conductivity in La(Sr)Ga(Fe,Mg)O3 and Its Application for Solid Oxide Fuel Cells.

Oxide ion conductivity in La(Sr)Ga(Fe,Mg)O 3 was investigated in this study and it was found that the oxide ion conductivity increased significantly by doping Fe into Ga site. Although the electrical conductivity monotonically increased with increasing amount of Fe, partial electronic conduction became significant. On the other hand, doping Mg for Ga site simultaneously with Fe is useful for keeping high transport number. By doping Fe for Ga site, perovskite oxide with cubic structure seems to be stabilized and the solid solution limit for Sr for La site is expanded. Considering the transport number of oxide ion and the electronic conductivity, the optimum composition for oxide ion conductivity in this system is La 0.7 Sr 0.3 Ga 0.7 Fe 0.2 Mg 0.1 O 3-δ (LSGFM73721). By using this oxide for electrolyte, large power density of 200mW/cm 2 can be achieved at 873 K.