Ba0.5Sr0.5[CoxZn0.2-x]Fe0.8O3–δ, (x = 0, 0.04, 0.08, 0.12) cathode formulations were successfully synthesized by solid state reactions and the effect of cobalt doping at Zn site of Ba0.5Sr0.5Zn0.2Fe0.8O3–δ (BSZF0.2) on the electrical conductivity, the polarization resistance and electrochemical behavior was evaluated. X-ray diffraction patterns indicate that a single cubic perovskite phase of Ba0.5Sr0.4Co0.8Fe0.2O3–δ oxide is successfully obtained. Ba0.5Sr0.5Co0.04Zn0.16Fe0.8O3–δ (BSCZF0.16) exhibited a high electrical conductivity of 10 S/cm at 400 °C in comparison to the BSZF0.2 showing 5.5 S/cm. Further, BSCZF0.16 also possess a low polarization resistance as low as 0.22, 0.38, 0.87, and 1.55 Ω cm2 at 750, 700, 650, and 600 °C in air, respectively. Accordingly, a low activation energy value of 149.8 kJ/mol for BSCZF0.16 in comparison to 159.4 kJ/mol for BSZF0.2 indicates high catalytic efficiency. Enhancement of desirable properties such as electrical conductivity in combination with low-polarization resistance and low-activation energy values can be attributed to the coexistence of Co and Zn in the B-site of BSCZF0.16 leading to the multivalent states which contributes to the enhanced electron transport properties demonstrating BSCZF0.16 as a better cathode for intermediate temperature solid oxide fuel cells applications.
Cathode Perovskite AC impedance Polarization resistance Electrical conductivity
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