La0.9Sr0.1Ga0.8Mg0.2O3-δ sintered by spark plasma sintering (SPS) for intermediate temperature SOFC electrolyte

The La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) powders for intermediate temperature SOFC electrolyte have been synthesized by glycine-nitrate combustion process. The as-synthesized powders show almost pure perovskite phase. And then, the as-synthesized powders were sintered by SPS at 1300 degrees C to prepare electrolyte. The SEM, XRD and AC impedance were employed to characterize the microstructure, phase and electrical conductivities. Results show that the grain size is very fine, less than 1 mu m, and the relative density of the pellet after sintering by SPS is about 94.7%. There is very little amount of secondary phases after SPS and the grain boundary and secondary phase resistance is very small. The electrolyte sintered by SPS shows higher conductivities than that sintered by conventional method at the same temperature. The activation energy at lower temperatures (400-700 degrees C) and higher temperatures (700-800 degrees C) is about 0.94 and 0.49 eV, respectively. Spark plasma sintering is a promising and effective method to sinter the LSGM electrolyte. (c) 2007 Elsevier B.V. All rights reserved.