Synthesis and performance of A-site deficient lanthanum-doped strontium titanate by nanoparticle based spray pyrolysis

In this study A-site deficient lanthanum doped strontium titanate, which is considered as a promising, redox-stable candidate for full ceramic anodes in Solid Oxide Fuel Cells (SOFCs), was produced by nanoparticle-based spray pyrolysis. In this process cost-effective nitrate salts and titania nanoparticles are used as precursors. LST with a nominal composition of La0.2Sr0.7TiO3 showed limited stability at temperatures higher than 1290 °C. It was observed that minor contents of secondary phases, which form at elevated temperatures, invoke a drastic loss of the electrical performance. Thermal stability is significantly increased by a slight enrichment of strontium. The phase pure A-site deficient LST shows remarkably higher electrical performance than similar stoichiometric counterparts. Reductive sintering results in a conductivity as high as 600 S cm−1 at 600 °C. Furthermore the A-site deficient LST shows a high redox-stability and fast redox-kinetics. With these properties LST is a suitable material for the fabrication of a new generation of Ni-free ceramic SOFC anodes. Secondary phases have a significant influence on the electrical conductivity and redox behaviour.

► We studied large scale powder synthesis of La0.2Sr0.7TiO3+δ by nanoparticle based spray pyrolysis. ► Spray pyrolysed La0.2Sr0.7TiO3+δ showed limited phase stability at temperatures higher than 1290 °C due to limited solubility of excessive titania. ► A-site deficient titanate showed remarkably better electrical performance than fully stoichiometric material. ► Minor contents of secondary phases significantly limited the material's performance. ► Single phase La0.2Sr0.704TiO3+δ sintered in reducing atmosphere gave a rise to 600 S cm−1 at 600 °C.