Stoichiometric lanthanum chromite based ceramic interconnects with low sintering temperature

Ceramic interconnects for use in solid oxide fuel cells are expected to operate between 800∼1000 °C, sinter between 1400∼1500 °C to allow co-firing and meet a number thermal mechanical requirements. The perovskite type (ABO₃) lanthanum chromite based materials have emerged as a leading candidate that will meet these criteria by varying the composition on the A and B sites. A need therefore exists to determine this material's temperature dependent electrical and mechanical properties with respect to these site substitutions. In this investigation, oxide powders were prepared by the glycine-nitrate process. Ionic substitutions were carried out on A sites with calcium or strontium, and B sites with cobalt and aluminum, respectively. Only stoichiometric compositions were considered for the sake of stability. The powders and their sinterability were investigated by XRD, SEM, dilatometry and density measurements. The sintered materials were further examined by SEM, thermal expansion and electric conductivity measurements in order to elucidate the resulting microstructure, electrical and mechanical properties.