Sintering Characteristics and Electrical Conductivity of (Sr1-xLax)TiO3 Synthesized by the Citric Acid Method

The air-sintering characteristics and electrical conductivity of (Sr1-xLax)TiO3 perovskites (0 <= x <= 0.3) synthesized by the citric acid method were evaluated in terms of their use as interconnect materials in solid oxide fuel cells. A single perovskite phase of (Sr0.8La0.2)TiO3 powder was formed at 800 degrees C. In this powder, a Ruddlesden-Popper Sr2TiO4 layer appeared in the temperature range of 1100-1500 degrees C, and disappeared at 1600 degrees C. (Sr0.8La0.2)TiO3 powders which were calcined at 1000-1100 degrees C showed the best sintering characteristics. The relative density of the samples reached 94% at 1400 degrees C, although the Ruddlesden-Popper layer remained in this dense sample. Electrical conductivities of (Sr1-xLax)TiO3 bars at 1000 degrees C were approximately 0.10-1.1 S cm(-1) in air and 7.1-12 S cm(-1) in a reducing atmosphere. For a (Sr0.9La0.1)TiO3 pellet placed between both air and reducing atmospheres, the conductivity at 850 degrees C was 0.033 S cm(-1), which is close to that in air. No compositional dependency on electrical conductivity was observed for the (Sr1-xLax)TiO3 pellets. [DOI: 10.1115/1.4003993]