Ceria-based solid electrolytes for IT-SOFC applications

Abstract

In this study, doped ceria solid electrolyte materials Ce0.8M0.2O2−δ (M = Gd, Sm, and Nd) for intermediate temperature-solid oxide fuel cells were synthesized through citrate-nitrate auto combustion method. They were then characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared (FT-IR) techniques. XRD results show that all the synthesized powders indicate a single-phase with cubic fluorite structure. Electrolytes with high density were obtained by sintering the samples at 1400◦C for 6 h. The mean crystallite sizes were calculated using the Scherrer formula. Surface morphologies of all the sintered electrolytes were obtained by using SEM. The total ionic conductivity of all electrolytes was measured from the impedance analysis in 300–700◦C temperature range. The ionic conductivities at 700◦C are in the order of Ce0.8Sm0.2O2−δ >Ce0.8Gd0.2O2−δ >Ce0.8Nd0.2O2−δ, and their corresponding activation energies are found to be 0.61, 0.62, and 0.67 eV, respectively.