Perovskite-type cathode materials La0.6Sr0.2Ca0.2Co1-yFeyO3-δ(0.2≤y≤0.5, marked as LSCCF62282, LSCCF62273, LSCCF62264 and LSCCF62255) for intermediate-temperature solid oxide fuel cells (IT-SOFCs) were prepared by solid state reaction. The establishment process and phase transformation were measured by TG-DTA, FT/IR and XRD techniques. Single hexagonal perovskite phase can be achieved after sintered at 1100 °C for 3 h. Mixed conductivity, thermal expansion behavior and chemical stability of sintered samples at 1100 °C for 3 h have been investigated. At intermediate temperature (600-800 °C), the mixed conductivity characterized by DC four-probe technique is higher than 100 S/cm. LSCCF62282 has the highest conductivity of 297.3 S/cm at 700 °C among the four samples. At lower temperatures, the conductivity follows small polaron hopping mechanism. Thermal expansion coefficients (TECs) of the samples from 50 °C to 850 °C exhibit a reducing tendency with increasing amount of doped Fe3+. Thermal expansion behavior can be improved by doping with Ca2+and Fe3+commonly. XRD pattern for LSCCF62282 and YSZ mixture sintered at 800 °C for 6h indicates that cathode material LSCCF62282 is chemically stable against YSZ electrolyte at operating temperature.
Crystal Structure and Thermal Expansion Behavior of La0.7Sr0.3Ga0.7Fe0.2Mg0.1O3-.DELTA. at High Temperature-Effect of Chemical State of Fe and Oxygen Nonstoichiometry-
