A-Site Deficient (Pr[sub 0.6]Sr[sub 0.4])[sub 1−s]Fe[sub 0.8]Co[sub 0.2]O[sub 3−δ] Perovskites as Solid Oxide Fuel Cell Cathodes

Five A-site deficient ( Pr 0.6 Sr 0.4 ) 1 − s Fe 0.8 Co 0.2 O 3 − δ perovskites ( s = 0.01 , 0.05, 0.10, 0.15, and 0.20) were synthesized using the glycine-nitrate process. The perovskites were characterized with powder X-ray diffraction (XRD), dilatometry, four-point dc conductivity measurements, and electrochemical impedance spectroscopy using cone-shaped electrodes on a Ce 0.9 Gd 0.1 O 1.95 electrolyte. XRD revealed that only the compounds with s = 0.01 and 0.05 were of single phase. The other compounds contained an additional phase in the form of a Co–Fe spinel. The thermal expansion coefficient decreased systematically with an increase in s . The total conductivity followed the small polaron hopping process below a certain characteristic temperature. The total conductivity decreased with increasing s . It was likewise shown that the polarization resistance found a minimum for the compound with s = 0.05, with a total area specific resistance more than 3 times lower than the weakly A-site deficient ( Pr 0.6 Sr 0.4 ) 0.99 Fe 0.8 Co 0.2 O 3 − δ perovskite.