Characterization of the Microstructure and Electrical Conductivity of Plasma-Sprayed La_0.5Sr_0.5CoO₃ Coating

Abstract

Lanthanum strontium cobalt oxide (LSCO) has been employed as cathode and intercollector materials for solid oxide fuel cells (SOFCs). In the present study, the La_0.5Sr_0.5CoO₃ layer was deposited by atmospheric plasma spray (APS). The effect of heat treatment on microstructure and electrical conductivity of the LSCO deposits was examined. The electrical conductivity of the deposits along the lamellar direction was measured by a four-probe dc approach. The microstructure of the deposit was characterized by scanning electron microscopy and X-ray diffraction analysis. The results showed that the electrical conductivity of plasma-sprayed LSCO coating was lower than that of sintered bulk material with the same composition. The minor metastable phase in the as-sprayed coating reduced the electrical conductivity. The annealing treatment at 1000°C led to the elimination of the metastable phase and improved the electrical conductivity. The lamellar structure features with the limited interface bonding limits the electrical conductivity.