Preparation and Properties of Multi-Elements Doped Perovskite-Type Mixed Conductors for IT-SOFC Cathodes

Abstract

Multi-elements doped LaCoO3-based mixed conductors La0.7Sr0.1Ca0.1Co0.8Fe0.2O2.9 (LSCCF-112) and La0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (LSCCF-213) were synthesized by conventional solid state reaction (CSSR). The forming process, microstructure and crystal structure of the prepared samples were analyzed by TG/DTA, SEM and XRD. The mixed conductivities of the samples were measured using DC four-terminal method in 150-950 °C. Thermal expansion coefficients (TEC) of the samples were tested in 20-950°C. LSCCF-112 and LSCCF-213 exhibit pure perovskite phase and porous structure after sintered at 1200 °C. The average TECs of LSCCF-112 and LSCCF-213 are 18.17×10-6 K-1 and 17.52×10-6 K-1 respectively. The mixed conductivity of the samples shows semiconducting behavior up to 700-750°C and then decreases as the temperature is further raised. At intermediate temperature (IT), the conductivity values of the samples are both much higher than 100 S/cm.