Microstructure and Impedance Analysis of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) for Solid Oxide Fuel Cell Cathode

Composite perovskite oxides La_(1-x)Sr_xCo_(1-y)Fe_yO_(3-δ) (LSCF) is an optional cathode ma- terial for the intermediate temperature solid oxide fuel cells.La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) powders were synthesized by a citrate method.The effects of the precursor solution pH value and the calcining tem- perature on the phase structure of the LSCF powders were investigated by X-ray diffraction.Besides, the impacts of the precursor solution pH value and sintering temperature on the morphology and im- pedance characteristics of the LSCF sintered bodies were studied by SEM,AC impedance analysis, respectively.The alternate-current impedances of the LSCF sintered bodies were analysized based on the Voigt-type equivalent circuit model.The results show that the LSCF sintered body has the lowest impedance in the condition that the precursor solution pH is 4,the calcination temperature is 900℃, and the sintering temperature is 1400℃for 2h,respectively.