Ln1−xSrxCoO3(Ln = Sm, Dy) for the electrode of solid oxide fuel cells
Abstract The perovskite-type oxides were synthesized in the series of Ln 1− x Sr x CoO 3 (Ln = Sm, Dy). The formation of solid solutions in Dy 1 − x Sr x CoO 3 was limited, compared with that in Sm 1 − x Sr x CoO 3 . The electrical conductivities of the sintered samples were measured as a function of x in the temperature range 30 to 1000 °C. The highest conductivity of around 500 S/cm at 1000 °C was found in Sm 0.7 Sr 0.3 CoO 3 . The reactivity of all the samples with YSZ was examined at 800–1000 °C for 96 h. The Sr-doped perovskite oxides were more reactive with YSZ and produced SrZrO 3 at 900 °C after 96 h. However, no reaction product between SmCoO 3 and YSZ was observed at 1000 °C for 96 h. The cathodic polarization of the oxide electrodes, sputtered on yttria stabilized zirconia (YSZ), was studied at 800–1000 °C in air. SmCoO 3 shows no degradation of the electrode performance at higher temperatures. The thermal expansion measurements on the sintered samples were carried out from room temperature to 1000 °C. Large thermal expansion coefficients were found in these samples.