Electrical properties and reducibilities of ceria-rare earth oxide systems and their application to solid oxide fuel cell

Ionic conductivities of ceria-rare earth oxide system were investigated in relation to their structures, electrical conductivities, and reducibilities. Rare earth oxides were soluble in fluorite lattice of ceria at low additive concentrations. The electrical conductivities of ceria-rare earth oxide systems depended on ionic radii of the added cation. Samarium and gadolinium-added ceria samples showed the highest electrical conductivity because of the close ionic radii of Sm3+ and Gd3+ to the radius of Ce4+. These systems exhibited the wide electrolytic region in conductivity versus Po2 plots as compared with ceria-calcia and -yttria systems. The ceria-samarium oxide samples exhibited a high power for solid oxide fuel cell at relatively low temperatures (873–1073 K).