Investigation on the Sr-doped ceria Ce1−xSrxO2−δ (x = 0.05–0.2) as an electrolyte for intermediate temperature SOFC

•Ce1−xSrxO2−δ (x = 0.05–0.2) were synthesized by citrate-complexation method.•Pure solid solution was found for x = 0.05 unlike other compositions.•Raman spectra confirms the existence SrCeO3 secondary phase for x > 0.05.•Conductivity decreases with increase in x for Ce1−xSrxO2−δ (x = 0.05–0.2).•Sr-doped ceria here showed higher conductivity when compared to rare-earth doped ceria.

The effect of Sr doping in CeO2 for its use as solid electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce1−xSrxO2−δ (x = 0.05–0.2) are successfully synthesized by citrate-complexation method. XRD, Raman, FT-IR, FE-SEM/EDX and electrochemical impedance spectra are used for structural and electrical characterizations. The formation of well crystalline cubic fluorite structured solid solution is observed for x = 0.05 based on XRD and Raman spectra. For compositions i.e., x > 0.05, however, a secondary phase of SrCeO3 is confirmed by the peak at 342 cm−1 in Raman spectra. Although the oxygen ion conductivity was found to decrease with increase in x, based on ac-impedance studies, conductivity of Ce0.95Sr0.05O2−δ was found to be higher than of Ce0.9Gd0.1O2−δ and Ce0.8Gd0.2O2−δ. The decrease in conductivity of Ce1−xSrxO2−δ with increasing dopant concentration is ascribed to formation of impurity phase SrCeO3 as well as the formation of neutral associated pairs, SrCe″-Vo. The activation energies are found to be 0.77, 0.83, 0.85 and 0.90 eV for x = 0.05, 0.1, 0.15 and 0.20, respectively.

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