Oxygen-loss in A-site deficient Sr0.85La0.10TiO3 perovskite

The electrical properties of Sr1-3xLa2xTiO3 ceramics (x = 0.05, LST) change dramatically with sintering temperature and atmosphere. Ceramics sintered at 1200 degrees C in both O-2 and N-2 exhibit near intrinsic band-type conduction with bulk conductivity similar to 10(-7) S cm(-1) at 500 degrees C and activation energy for conduction, E-a of similar to 1.6-1.8 eV. LST ceramics sintered at 1450 degrees C in O-2 exhibit much higher bulk conductivity (>10(-4) S cm(-1) at -50 degrees C) with an E-a similar to 0.16 eV. For LST ceramics sintered at 1450 degrees C in N-2, 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 degrees C under both O-2 and N-2 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.