Preparation and electrical properties of gadolinium-doped strontium tungstate electrolyte for SOFC

Gadolinium-doped strontium tungstate (Sr1-xGdxWO4+delta) powders were synthesized by the sol-gel auto-combustion method, and their electrical properties were investigated. The phase formation of Sr1-xGdxWO4+delta powders was studied by the X-ray diffraction (XRD) analysis. The characterization of microstructure was carried out on the sintered ceramic discs. Electrochemical impedance spectroscopy (EIS) was used to estimate the electrical properties. The results displayed that these crystalline powders were scheelite-type tetragonal structures and demonstrated higher sinterability. The Sr1-xGdxWO4+delta electrolyte ceramics with a relative density over 95% of the theoretical density were obtained after the sintering process. The electrical conductivities of Sr1-xGdxWO4+delta increased significantly with increasing of doped-Gd3+ content and reached 6.89 x 10(-3) S.cm(-1) at 800 degrees C, when the doping amount was x = 0.3. At last, this study demonstrated that Sr1-xGdxWO4+delta is an effective strategy to optimize middle or low-temperature SOFC.