A-Site Deficient (Pr0.6Sr0.4)1-sFe0.8Co0.2O3-δ Perovskites as Solid Oxide Fuel Cell Cathodes

Five A-site deficient (Pr0.6Sr0.4)(1-s)Fe0.8Co0.2O3-delta 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 Ce0.9Gd0.1O1.95 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 (Pr0.6Sr0.4)(1-s)Fe0.8Co0.2O3-delta perovskite. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3194786] All rights reserved.