High-purity sintered samples of SrCe1-xYbxO3, where x was equal to 0, 0.025, or 0.05, were prepared. The materials had small pores, and a relatively homogeneous grain size of about 20. The variation in conduction was also detected by emf measurements of H concentration cells. Density measurements indicated that the dopant Y ions introduced O vacancies into the crystal structure and enhanced sintering. Impedance measurements were carried out, at temperatures ranging from 500 to 1250K, in various atmospheres. The results showed that impurity alumina acted as an insulator to proton conduction. Impedance measurements of the x = 0 samples failed at 673 and 2073K because of their extremely low conductivity, but the conductivity increased with doping content. The activation energy was equal to 0.55eV for x = 0.05 and to 0.59eV for x = 0.025. These energies were lower than most reported values. At higher temperatures, the effect of the atmosphere upon the conductivity became noticeable. Chemical analysis indicated that samples which had been prepared by alumina ball milling and then calcined in an alumina crucible contained 1.98wt% of alumina which was mainly segregated in the grain boundaries. The impedance spectra of such samples exhibited a lower conductivity (0.000455S/cm at 876K) and a higher activation energy (0.85eV).

M.Zheng, B.Zhu: Solid State Ionics, 1995, 80[1-2], 59-65