Abstract: The precursor of La_0.8Sr_0.2Co_xFe_1-xO₃ (x=1.0, 0, 0.3) oxygen diffusion barriers were prepared by a combined co-precipitation-gel method. The structure and properties of three different powders and ceramics were analyzed by X-ray diffraction, transmission electron microscope, scanning electron microscope and impedance spectroscope. The results show that La_0.8Sr_0.2Co_xFe_1-xO₃ (x=1.0, 0, 0.3) powders calcined at 870℃ have perovskite-type structure with no hard agglomerates, and their particle sizes are in the range of 20-60 nm. After are La_0.8Sr_0.2CoO₃ and the La_0.8Sr_0.2FeO₃ mix conductor pressed isostatically at 250MPa and then sintered at 1120℃ for 6h, their conductivities are in the order of 10^-1S/cm in air. While the sintered La0.8Sr_0.2Co_0.3Fe_0.7O₃ conductivity is up to 100 S/cm magnitude. The electronic conductivity of La_0.8Sr_0.2Co_xFe_1-xO₃ (x=1.0, 0, 0.3) ceramic is much bigger than ionic conductivity. The conductivities of the ceramics reach the maximum in the temperature range of 200-300℃, which tend to the lower temperature than those reported in the literature.

Key words: La_0.8Sr_0.2Co_xFe_1-xO₃(x=1.0、0、0.3), oxygen diffusion barrier, mixed conductor, perovskite-type