Ln 0.4Sr 0.6Co 0.8Fe 0.2O 3− δ (Ln=La, Pr, Nd, Sm, Gd) for the electrode in solid oxide fuel cells

Abstract

Perovskite-type oxides of Ln 0.4Sr 0.6Co 0.8Fe 0.2O 3− δ (Ln=La, Pr, Nd, Sm, Gd) have been prepared by the solid state reaction of corresponding oxides. The electrical conductivity of the sintered samples showed semiconductor-like behavior at a lower temperature and metallic behavior at a higher temperature. Nd 0.4Sr 0.6Co 0.8Fe 0.2O 3− δ exhibited the highest conductivity in Ln 0.4Sr 0.6Co 0.8Fe 0.2O 3− δ in the temperature range of 25–1000°C. The reactivity test of these oxides with 8 mol% Y 2O 3 doped zirconia (8YSZ) was carried out between 800 and 1000°C for 96 h in air. The perovskite oxides reacted with 8YSZ to produce SrZrO 3 at 900°C and no reaction product was observed at 800°C. The cathodic polarization of these oxide electrodes sputtered on the 8YSZ tablet was studied at 600–800°C in air. Nd 0.4Sr 0.6Co 0.8Fe 0.2O 3− δ showed the best catalytic activity for oxygen reduction. These perovskite oxides showed no degradation of the electrode performance by annealing between 600 and 800°C.