Preparation, thermal expansion and electrical conductivity of La0.6Sr0.4Co1−xGaxO3−δ (x=0.0–0.4) as a new cathode material of SOFC

Preparation, thermal expansion, electrical conductivity and polarization of La0.6Sr0.4Co1−xGaxO3−δ (LSCG) (x=0.0–0.4) were studied in order to estimate the potential as a new material for cathode of intermediate temperature solid oxide fuel cells (ITSOFC). Within x≦0.4, hexagonally distorted perovskite single phase of La0.6Sr0.4Co1−xGaxO3−δ was obtained. Thermal expansion coefficients (TEC) of the specimens with x<0.3 showed higher values than those of electrolyte materials, such as Ce0.8Gd0.2O1.9 or La0.8Sr0.2Ga0.85Mg0.15O2.825, whereas those of specimens with x=0.3 showed close value. The electrical conductivity decreased with increasing Ga content; however, the conductivity for x=0.4 is still in the order of 102 S/cm at 800 °C. Polarization measurements showed that cathode performance decreased with increasing Ga content; however, the sample with x=0.4 still has sufficient activity as a new cathode material of ITSOFC.