Synthesis and Properties of La_(0.8)Sr_(0.2)Co_xFe_(1-x)O_3 Mixed Ionic and Electronic

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℃ 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 1120℃ for 6h,their conductivities are in the order of 10-1S/cm in air.While the sintered La0.8Sr0.2Co0.3Fe0.7O3 conductivity is up to 100 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℃,which tend to the lower temperature than those reported in the literature.