Electrical conductivity and stability of A-site deficient (La, Sc) co-doped SrTiO3 mixed ionic-electronic conductor

Mixed ionic–electronic conductors with high ionic conductivity play an important role in modern solid-state ionic devices. The ionic conductivity of SrTiO3-based materials can be significantly improved by creating deficiency on the A-site and acceptor-doping on the B-site. We report in this paper a remarkable enhancement of ionic conductivity, sinterability and thermal stability of (La, Sc) co-doped SrTiO3 by creating deficiency on the A-site. The ionic conductivity of (La0.3Sr0.7)0.95Sc0.10Ti0.90O3–δ varies from 0.005 S/cm at 500 °C to 0.01 S/cm at 700 °C and to 0.018 S/cm at 950 °C in 5%H2/Ar. These values are nearly eight times higher than that of La0.3Sr0.7TiO3–δ at T ≥ 700 °C. The A-site deficiency in (La, Sc) co-doped SrTiO3 also improves the thermal and electrical stabilities in various atmospheres. A possible charge compensation mechanism among defects in the (La0.3Sr0.7)0.95Sc0.10Ti0.90O3–δ is also discussed.