An Investigation of Doped Perovskites Based on La, Pr, and Sm Ferrites as Cathode Materials for Solid Oxide Fuel Cells

Perovskites with the composition ABO₃ have been studied as cathode candidate materials for solid oxide fuel cells. Both the A and B sites can be doped. This paper investigates ABO₃ perovskites in which the A site ion is lanthanum (La), praseodymium (Pr), or samarium (Sm), doped with strontium (Sr). The B site ion is iron (Fe) doped with cobalt (Co) or nickel (Ni). Powders were prepared by the glycine-nitrate process, and were calcined at temperatures between 700°C and 900°C. XRD analysis was performed to determine the effect of calcination temperature on structure. Cathode pellets were made and sintered at 1200°C for 4 hours. The electrical conductivity of these pellets was measured, in ambient air, at temperatures ranging from 200°C to 800°C. The measured conductivity was generally higher for the ferrite-nickelates than the ferrite-cobaltites. Additionally, the samples with lanthanum as the A site cation demonstrated higher electrical conductivity than those with samarium or praseodymium.