Atmospheric plasma-sprayed La_0.3Sr_0.7TiO_3-δ interconnect for high-temperature solid oxide fuel cells

Lanthanum-doped strontium titanate (LST) perovskite is regarded as a promising candidate for high-temperature solid oxide fuel cells (HT-SOFCs) interconnect material. In this paper, dense LST membranes were deposited on YSZ and steel substrates at the deposition temperature of ∼500°C by atmospheric plasma spraying (APS). The effects of particle size of LST powders on the chemical composition, phase composition, and electrical conductivity of LST deposits were studied due to the preferential evaporation of Sr during plasma spraying. When the LST particle size is <30 μm, the evaporation of Sr increased remarkably with the decrease of particle size. When the particle size is >30 μm, the evaporation loss of Sr was greatly reduced. The electrical conductivity of APS-sprayed LST deposits after treatment in the reducing atmosphere reached 29.4-25.9 S/cm and 12.6-9.4 S/cm at 600-850°C in hydrogen and nitrogen atmosphere, respectively. The LST coatings exhibited excellent phase and dimension stability in both reducing and oxidizing atmospheres during the test period at 900°C.