Effect of oxygen vacancies on electrical properties of Ce0.8Sm0.1Nd0.1O2−δ electrolyte: An in situ Raman spectroscopic study

Ce0.8Sm0.2O2−δ, Ce0.8Nd0.2O2−δ and Ce0.8Sm0.1Nd0.1O2−δ samples were prepared by a citrate sol–gel method. Effects of microstructures and oxygen vacancies of the samples on their electrical properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), in situ Raman spectroscopy and AC impedance spectroscopy. SEM results indicated that larger grains were formed on the Ce0.8Nd0.2O2−δ and Ce0.8Sm0.1Nd0.1O2−δ electrolytes compared to that on the Ce0.8Sm0.2O2−δ. In situ Raman spectra suggested that the concentration of oxygen vacancies of the Ce0.8Sm0.1Nd0.1O2−δ sample was the highest while that of Ce0.8Sm0.2O2−δ was the lowest. It was found that the difference in the electrical conductivity for these electrolytes was closely related to the microstructure and oxygen vacancies of the samples. The highest electrical conductivity obtained on the Ce0.8Sm0.1Nd0.1O2−δ sample was ascribed to its larger grain size and higher concentration of oxygen vacancies.