Microstructure and electrical conductivity of atmospheric plasma-sprayed LSM/YSZ composite cathode materials

Yttria stabilized zirconia and lanthanum strontium manganate (YSZ/LSM) have been employed to fabricate the composite cathode layer for solid oxide fuel cells (SOFCs). In the present study, the YSZ/LSM composite coating was deposited by atmospheric plasma spray (APS) using the mechanical blending LSM and YSZ with ratios of 50:50, 40:60, and 20:80 wt.%. The electrical conductivity of the composite coating was measured by the means of direct current (DC) measurement in the temperature range of 500-900°C. The electrical conductivity of the YSZ-50%LSM coating ranged from 2.17 to 3.60 S/cm along the direction parallel to the coating surface at the temperature range. For the same specimen, the electrical conductivity perpendicular to the plane is less than one-tenth of that in the plane. The anisotropy of the electrical conductivity is attributed to the phases of different properties in the composite coating and the APS coating structure characteristics. The results also showed that the electrical conduction of the composite was strongly influenced by the YSZ content.