Conductivity and microstructure analysis of ceria materials doped with multiple elements

Abstract In this study, CeO 2 -based electrolytes were synthesized by a solid-state reaction method. Specimens of Ce 0.8 A 0.2 O 2–δ ( A = Sm, Nd), (La 0.77 Sr 0.2 B 0.03 ) x Ce 1– x O 2–δ ( B = Ca, Ba and x = 0.15, 0.2), and Ce 0.8 Nd 0.2–y C y O 2–δ ( C = Y, Ca and y = 0.02, 0.03) were prepared using a sintering temperature of 1500 °C for periods of 2 and 4 h. The microstructures and electrical properties were then analyzed. All sintered samples were fluorite-type ceria-based solid solutions. The structural analysis reveals that grain size has a direct relation to the sintering time for doped samples. Furthermore, it was found that the appropriate Ca or Ba content can contribute to grain growth for La-doped and Nd-doped samples. The measured conductivity increased with the temperature in a linear manner. The Ce 0.8 Nd 0.18 Ca 0.02 O 1.89 and Ce 0.8 Nd 0.17 Ca 0.03 O 1.885 samples sintered for 4 h have higher AC conductivities among all samples, and the AC conductivities and activation energies of the Ce 0.8 Nd 0.18 Ca 0.02 O 1.89 and Ce 0.8 Nd 0.17 Ca 0.03 O 1.885 samples sintered for 4 h are 0.12 S/cm and 1.32 eV and 0.11 S/cm and 0.96 eV, respectively, at 800 °C.