A study of (Ba0.5Sr0.5)1-xSmxCo0.8Fe0.2O3-δ as a cathode material for IT-SOFCs

(Ba0.5Sr0.5)(1-x)SmxCo0.8Fe0.2O3-delta (BSSCF; x = 0.05-0.15) compounds were synthesized with EDTA-Pechini method and characterized by powder X-ray diffraction (XRD), electrical conductivity and thermal expansion coefficient (TEC) measurements, as well as the electrochemical impedance spectra measurement. According to the XRD results, the main phase of the material belongs to the cubic perovskite-type, and the lattice contracting with the increasing contents of Sm3+. The TEC of the compounds is 19.1-20.3 x 10(-6) K-1 from 30 to 800 degrees C, which close to the values of Co-based materials, such as Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF). And the conductivity of BSSCF is higher than that of BSCF; e.g., about 212% higher at 500 degrees C for the x = 0.15 compound. Electrochemical impedance spectra at intermediate temperature revealed the better electrochemical performance of BSSCF than BSCF; e.g., the total resistance values of BSSCF electrode is 2.98 Omega cm(2) at 500 degrees C, nearly 50% lower than that of BSCF. (c) 2006 Elsevier B.V. All rights reserved.