SCHEDULED MAINTENANCE
Oxygen-loss in A-site deficient Sr0.85La0.10TiO3 perovskite†
Abstract
The electrical properties of Sr1−3xLa2xTiO3 ceramics (x = 0.05, LST) change dramatically with sintering temperature and atmosphere. Ceramics sintered at 1200 °C in both O2 and N2 exhibit near intrinsic band-type conduction with bulk conductivity ∼10−7 S cm−1 at 500 °C and activation energy for conduction, Ea of ∼1.6–1.8 eV. LST ceramics sintered at 1450 °C in O2 exhibit much higher bulk conductivity (>10−4 S cm−1 at −50 °C) with an Ea ∼ 0.16 eV. For LST ceramics sintered at 1450 °C in N2, the bulk conductivity was too high to be measured by impedance spectroscopy even at 10 K. In addition, electrical heterogeneity is observed in LST pellets sintered at 1450 °C under both O2 and N2 where pellet outer surfaces are more resistive than the inner regions of the ceramic. The defect chemistry of Sr0.85La0.10TiO3 perovskite is discussed based on chemical doping and oxygen-loss mechanisms and we highlight the importance of A-site vacancies on the oxygen-loss mechanism in La-doped ST-based ceramics.
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