Synthesis and electrical properties of La0.6M0.4FeO3-δ (M=Ca, Sr, Ba) as cathodes for SOFCs

A series samples of La0.6M0.4FeO3-delta(M = Ca, Sr, Ba) perovskite-type oxides were prepared by glycine nitrate process (GNP). FTIR, TG-DSC, XRD and TEM techniques were used to characterize the chemical constitution, thermal stability and phase structure. The electrical conductivity of the samples was investigated by four-probe technique. With the increase of substituted-ionic radius, the temperature of phase formation increases, and the solid solubility decreases gradually, respectively. The La0.6Ca0.4FeO3-delta (LCF) powder is pure cubic perovskite-type crystalline after fired at 850 degrees C for 2 h. The XRD patterns of La0.6Sr0.4FeO3-delta(LSF) powder shows a small quantity of SrO peaks sintered at 1050 degrees C for 2 h. The electrical conductivity of LCF and LSF at 500 similar to 800 degrees C is over 100 S(.)cm(-1), and the value of LCF is 1170 S(.)cm(-1) at 800 degrees C, which indicate that LCF and LSF may be used as a profitable cathode for IT-SOFCs. The characteristic of La-0.6 Ba0.4FeO3-delta(LBF) is poor, and the electrical conductivity at intermediate temperatures is 1/20 less than that of LSF.