Characterization of atmospheric plasma-sprayed La 0.8Sr 0.2Ga 0.8Mg 0.2O 3 electrolyte

Abstract

La 0.8Sr 0.2Ga 0.8Mg 0.2O 3 (LSGM) deposit in free standing planar shape was prepared by atmospheric plasma spraying (APS) to examine the coating microstructure and electrical conductivity to aim at applying APS LSGM to solid oxide fuel cells (SOFCs). The electrical conductivity of the plasma-sprayed LSGM coating was investigated. The coating microstructure was characterized by X-ray diffraction and scanning electron microscopy. The result showed that a fraction amorphous phase was present in the as-sprayed LSGM deposit, which starts to recrystallize at the temperature of 785 °C. The electrical conductivities of the LSGM with recrystallization treatment are 0.04 and 0.09 S cm −1 at 1000 °C at the directions perpendicular and parallel to the coating surfaces, respectively. The electrical conductivity at perpendicular direction is about one-tenth that of sintered bulk at 1000 °C. This result is due to the lamellar structure feature with the limited interface bonding which dominates the electrical conductivity of APS coatings. The activation energy for ion conduction within APS-deposited LSGM deposit depends on temperature range. The change of activation energy indicates that the ion transportation dominant changes with temperature.