SOFC Cathodes Composed of LaNi0.6Fe0.4O3 and Pr-Doped CeO2

Solid oxide fuel cell (SOFC) cathodes consisting of LaNi 0.6 Fe 0.4 O 3 and Ce(Ln)O 2-δ (Ln = Pr, Sm, Gd) were investigated with the ac impedance method. The interface resistance of cathodes with Pr-doped ceria was approximately one-third of those with Sm- and Gd-doped ceria. Cathodes with Pr-doped ceria had frequency peaks in the imaginary part impedance spectra that were 100 times lower than those for cathodes without Pr-doped ceria. This low-frequency peak for the Pr-doped ceria was caused by its large interface capacitance. This suggests that triple-phase boundary is present over the entire surface of the Pr-doped ceria particles.