Property of (La, Ca) CrO₃ for interconnection in solid oxide fuel cell (Part 2) - Durability

The chemical stability of calcium doped lanthanum chromites as SOFC interconnect was investigated by annealing in air and durability test under the simulated SOFC operating conditions. The effects of calcium content, A-site excess, water vapor pressure and silicon as impurity were checked. Stable electrical conductivity was obtained in SOFC operating test up to 300 h for the samples with lower calcium content and no A-site excess under the silicon-free conditions. The powders calcined at higher temperatures resulted in better durability. After the tests, Ca₅(CrO₄)₃O_0.5 was detected in XRD on the surface exposed in oxidizing atmosphere. Silicon component reacts with Ca-rich secondary phase in the samples and form Ca₄SiO₄, which degrades the electrical conductivity.