Synthesis and Properties of La0.8Sr0.2CoxFe1-xO3 Mixed Ionic and Electronic Conducting Ceramics for Dense Diffusion Barriers

The precursor of La0.8Sr0.2CoxFe1-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 La0.8Sr0.2CoxFe1-xO3 (x= 1.0, 0, 0.3) powders calcined at 870 degrees C have perovskite-type structure with no hard agglomerates, and their particle sizes are in the range of 20-60 nm. After are La0.8Sr0.2CoO3 and the La0.8Sr0.2FeO3 mix conductor pressed isostatically at 250MPa and then sintered at 112 degrees C. for 6h, their conductivities are in the order of 10(-1)S/cm in air. While the sintered La0.8Sr0.2Co0.3Fe0.7O3 conductivity is up to 10(0)S/cm magnitude. The electronic conductivity of La0.8Sr0.2CoxFe1-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 degrees C, which tend to the lower temperature than those reported in the literature.