Synthesis & characterization of Ti and Fe co-doped Ta2O5 based solid electrolytes for SOFC

Ta1-x-yTixFeyO5 (-) (delta) was synthesized by co-precipitation. Their crystal structure, microstructure, electric conductivity, thermostability and coefficient of thermal expansion (CTE) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectra (EIS), Thermogravimetric (TGA) and thermal dilatometer, respectively, and the effects of Fe2O3 content on the above properties were investigated. The results of XRD showed the crystal pattern changed from orthorhombic to triclinic structure. SEM analysis showed the sintering and densification of electrolyte had been promoted with the introduction of Fe2O3. Ta1-x-yTixFeyP5 (-) (delta) had the highest electric conductivity of 4.02 x 10(-2) S/cm when x = 0.077, y = 0.023 and good thermal performance at high temperature.