THERMAL AND ELECTRICAL PROPERTIES OF Ba0.5Sr0.5CoxFe1-x-yNiyO3-delta (x = 0.4, 0 <= y <= 0.25) AS CATHODE MATERIAL FOR IT- SOFCs

Ba0.5Sr0.5CoxFe1-x-yNiyO3-delta (BSCFNi; x = 0.4, 0 <= y <= 0.25) were studied in relation to their potential use as intermediate temperature solid oxide fuel cell (IT-SOFC) cathode. An emphasis is made on the e r ect of Ni-doping on crystal structure, thermal expansion coefficient (TEC) and dc electrical conductivity. A cubic perovskite structure was observed in the X-ray di r raction (XRD) measurement. The TEC of BSCFNi obtained for 0 <= y <= 0.25, varies in the range of (12.38-18.81) x 10(-6) K-1, measured in the temperature range of 30 degrees C to 800 degrees C. The electrical conductivity which is a major defect of Ba0.5Sr0.5CoxFe1-x-yNiyO3-delta (BSCF) was improved by Ni-doping. The compound with y = 0.20 and 0.25 demonstrated a conductivity of sigma = 62.59 S-cm(-1) and 72.64 S-cm(-1) at 400 degrees C and 77.01 S-cm(-1) and 89.68 S-cm(-1) at 500 degrees C.