Ln0.4Sr0.6Co0.8Fe0.2O3-δ (Ln = La, Pr, Nd, Sm, Gd) for the electrode in solid oxide fuel cells

Perovskite-type oxides of Ln(0.4)Sr(0.6)Co(0.8)Fe(0.2)O(3-delta) (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. Nd0.4Sr0.6Co0.8Fe0.2O3-delta exhibited the highest conductivity in Ln(0.4)Sr(0.6)Co(0.8)Fe(0.2)O(3-delta) in the temperature range of 25-1000 degrees C. The reactivity test of these oxides with 8 mol% Y2O3 doped zirconia (8YSZ) was carried out between 800 and 1000 degrees C for 96 h in air. The perovskite oxides reacted with 8YSZ to produce SrZrO3 at 900 degrees C and no reaction product was observed at 800 degrees C. The cathodic polarization of these oxide electrodes sputtered on the 8YSZ tablet was studied at 600-800 degrees C in air. Nd0.4Sr0.6Co0.8Fe0.2O3-delta showed the best catalytic activity for oxygen reduction. These perovskite oxides showed no degradation of the electrode performance by annealing between 600 and 800 degrees C. (C) 1999 Elsevier Science B.V. All rights reserved.