Characterization and stability of La0.7Sr0.3Co0.3Fe0.7O3 perovskite-type oxide

Abstract

Compositely doped oxide La07Sr03Co03Fe07O3 (LSCF) was synthesized using solid state reaction and citric acid-nitrate low temperature self-propagating combustion methods. The crystal structure and the particle size micrograph of LSCF powders synthesized by different methods were investigated with XRD and SEM. The experimental results show that the single perovskites phase of LSCF can be synthesized by both methods. The particle size of LSCF by citric acid-nitrate low temperature self-propagating combustion method was the smaller. Two types of cathodes wafers were fabricated with the two kinds of LSCF powders and Ce0.9Gd0.1O1.95 (GDC) at the mass rate of 6:4, respectively. The electrical conductivity of sintered samples was measured by four probe DC method from 100°C-800°C. The cathode with LSCF particle by citric acid-nitrate low temperature self-propagating combustion method has the higher electrical conductivity. The conduction mechanism for the samples is attributable to the adiabatic-hopping of p-type small polaron. In order to investigate the stability, the samples were put into the muffle furnace to heat up in air at 800°C for 800h. To analyze the reason for reduced electrical conductivity, the crystal structure and the particle micrograph of the cathodes before and after exposure were investigated with XRD and SEM. The result shows that both cathodes have good stability, good compatibility with GDC. The sample micrographs do not change too much. The electrical conductivity of the two cathodes reduces a little after exposure.