Summary
Perovskite‐type (ABO3) complex oxides of Sm1‐xSrxFe0.7Cr0.3O3‐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 Sm1‐xSrxFe0.7Cr0.3O3‐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. Sm0.3Sr0.7Fe0.7Cr0.3O3‐δ (x = 0.7) was determined to be the optimal composition in the Sm1‐xSrxFe0.7Cr0.3O3‐δ series based on a trade‐off between the thermal expansion and electrocatalytic properties. Sm0.3Sr0.7Fe0.7Cr0.3O3‐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, Sm0.3Sr0.7Fe0.7Cr0.3O3‐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 Sm0.3Sr0.7Fe0.7Cr0.3O3‐δ is a potential candidate material for cathode of IT‐SOFCs in light of its overall properties.