Low thermal expansion Tb_1−xCa_xBaCo_3.2Ga_0.8O_7+δ (x = 0, 0.25, 0.50 and 0.75) Swedenborgite-type oxide cathodes for solid oxide fuel cells

The Tb_1−xCa_xBaCo_3.2Ga_0.8O_7+δ (x = 0, 0.25, 0.50 and 0.75, abbreviated as TCBCG00, TCBCG25, TCBCG50 and TCBCG75) Swedenborgite-type oxides are successfully prepared by solid-state reaction methods. The effect of Ca doping on the properties associated with cathode materials has been investigated. Ca doping resulted in a decrease in the cell volume of the material from 357.289 ų for TCBCG00 to 355.376 ų for TCBCG75. The appropriate amount of Ca doping does not degrade the high temperature stability of the material, and TCBCG25 and TCBCG50 showed better stability than TCBCG00 and TCBCG75. Ca doping does not significantly affect the coefficient of thermal expansion and the Tb_1−xCa_xBaCo_3.2Ga_0.8O_7+δ material has a lower coefficient of thermal expansion. With the increase of Ca content, the carrier concentration is increased, and the conductivity is significantly improved. TCBCG25 has the best catalytic activity with an area specific resistance of 0.021 Ω cm² and a peak power density of 746 mW cm⁻² at 800 ^oC. The current results show that TCBCG25 is a promising new cathode material.