Electrical conduction behavior of La, Co co-doped SrTiO3 perovskite as anode material for solid oxide fuel cells

The effects of La- and Co-doping into SrTiO3 perovskite oxides on their phase structure, electrical conductivity, ionic conductivity and oxygen vacancy concentration have been investigated. The solid solution limits of La in LaxSr1 − xTiO3 − δ and Co in La0.3Sr0.7CoyTi1 − yO3 − δ are about 40 mol% and 7 mol%, respectively, at 1500 °C. The incorporation of La decreases the band gap and thus increases the electrical conductivity of SrTiO3 remarkably. La0.3Sr0.7TiO3 − δ shows an electrical conductivity of 247 S/cm at 700 °C. Co-doping into La0.3Sr0.7TiO3 − δ increases the oxygen vacancy concentration and decreases the migration energy for oxygen ions, leading to a significant increase in ionic conductivity but at the expense of some electrical conductivity. The electrical and ionic conductivities of La0.3Sr0.7Co0.07Ti0.93O3 − δ are 63 S/cm and 6 × 10−3 S/cm, respectively, at 700 °C. Both La0.3Sr0.7TiO3 − δ and La0.3Sr0.7Co0.07Ti0.93O3 − δ show relatively stable electrical conductivities under oxygen partial pressure of 10−14–10−19 atm at 800 °C. These properties make La0.3Sr0.7Co0.07Ti0.93O3 − δ a promising anode candidate for solid oxide fuel cells.