Dense La_0.3Sr_0.7TiO₃ interconnect sintered in air atmosphere at a reduced temperature with improved conductivity for solid oxide electrochemical cells

La-doped SrTiO₃ (La_xSr_1−xTiO₃, LST), as the promising ceramic-based interconnect material, usually needs to be sintered in reductive atmosphere at a temperature ≥ 1450 °C, such sintering condition is not friendly to cell fabrication and application. To reduce the sintering temperature of air-sintered LST, seven sintering additives, Bi₂O₃, Fe₂O₃, Li₂O, MnO₂, NiO, V₂O₅, and Co₃O₄, are added to the LST in this work. The results show that only Co₃O₄ is conductive to remarkable sintering at the temperatures of 1250 °C. The relative density of LST-3%Co₃O₄ reaches 92%, while that of the pure LST is only 48%. Moreover, the conductivity of LST-3%Co₃O₄ achieves 8.2 S/cm at 800 °C in humidified hydrogen, which exceed 5.5 times that of the pure LST. Interestingly, LST-3%Co₃O₄ exhibits an average TEC of 11.5 × 10⁻⁶ K⁻¹ between 400 and 900 °C, which is very close to that of other components of SOCs.