Dense La0.3Sr0.7TiO3 interconnect sintered in air atmosphere at a reduced temperature with improved conductivity for solid oxide electrochemical cells

Abstract

La-doped SrTiO3 (LaxSr1-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 8.2S/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 11.5×10-6K-1 between 400 and 900 °C, which is very close to that of other components of SOCs.