Yttrium-Substituted (La, Y, Sr)MnO3 as a SOFC Cathode Material.

Abstract

A material consisting of (La1-xYx)0.7Sr0.3MnO3 was synthesized and evaluated to enhance the thermal expansion compatibility with an electrolyte material of Solid Oxide Fuel Cells (SOFC) compared with the standard system La0.7Sr0.3MnO3. In addition, its crystal structure, chemical stability, electrical conductivity and electrode performance were examined. For the substitution range x=0.0-0.2 in the (La1-xYx)0.7Sr0.3MnO3 system, a single perovskite phase was observed. The mixture of (La1-xYx)0.7Sr0.3MnO3 (x=0.0-0.6) and YSZ, which was fired at 1400°C after mixing, did not contain the reaction products, such as La2Zr2O7, Y4Zr3O12, and SrZrO3. The average thermal expansion coefficients between 50°C and 1000°C at x=0.0 and x=0.2 were 12.2×10-6K-1 and 11.5×10-6K-1, respectively. The electrical conductivity of the phases with x=0.0 and 0.2, at 1000°C in air, were 172 and 217S·cm-1, respectively. The electrode performance of (La0.8Y0.2)0.7Sr0.3MnO3 was almost equal to that of La0.7Sr0.3MnO3 at 1000°C. Substitution of Y at the content of x=0.2 proved to be effective in obtaining higher expansion compatibility and electrical conductivity than the standard system without any degradation of the other properties.