Property evaluation of Sm1‐xSrxFe0.7Cr0.3O3‐δ perovskites as cathodes for intermediate temperature solid oxide fuel cells

Perovskite‐type (ABO₃) complex oxides of Sm_1‐xSr_xFe_0.7Cr_0.3O_3‐δ (x = 0.5‐0.7) series were prepared by a glycine‐nitrate combustion process. The crystal structure, oxygen nonstoichiometry, electrical conducting, thermal expansion, and electrocatalytic properties of Sm_1‐xSr_xFe_0.7Cr_0.3O_3‐δ perovskites were inspected in view of their use as cathode materials for intermediate temperature solid oxide fuel cells (IT‐SOFCs). Changing the content of Sm³⁺ at the A‐site was demonstrated to be effective in tuning the structure and properties. The variation of the various properties with Sm³⁺ content was explained in relation to the corresponding evolution of the crystal structure and oxygen nonstoichiometry. Sm_0.3Sr_0.7Fe_0.7Cr_0.3O_3‐δ (x = 0.7) was determined to be the optimal composition in the Sm_1‐xSr_xFe_0.7Cr_0.3O_3‐δ series based on a trade‐off between the thermal expansion and electrocatalytic properties. Sm_0.3Sr_0.7Fe_0.7Cr_0.3O_3‐δ ceramic specimen exhibited an electrical conductivity of approximately 40 S·cm^?1 at 800°C and a thermal expansion coefficient of 14.1 × 10^?6 K^?1 averaged in the temperature range from 40°C to 1000°C. At 800°C in air, Sm_0.3Sr_0.7Fe_0.7Cr_0.3O_3‐δ electrode showed a cathodic polarization resistance of 0.19 Ω·cm², a cathodic overpotential of 30 mV at current density of 200 mA·cm^?2, and an exchange current density of 257 mA·cm^?2. It is suggested that Sm_0.3Sr_0.7Fe_0.7Cr_0.3O_3‐δ is a potential candidate material for cathode of IT‐SOFCs in light of its overall properties.