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

Abstract

Five A-site deficient (Pr0.6 Sr0.4) 1-s Fe0.8 Co0.2 O3-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 Ce0.9 Gd0.1 O1.95 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 (Pr0.6 Sr0.4) 0.99 Fe0.8 Co0.2 O3-δ perovskite. © 2009 The Electrochemical Society.