Ionic Conductivities and Microstructures of Ytterbium-Doped Ceria

The ionic conductivities and microstructures of Ce 1 − x Yb x O 2 − x ∕ 2 ( x = 0.10 , 0.15, 0.20, and 0.25) with average grain sizes in a range of 0.2 – 3.7 μ m were studied systematically. Nanosized domains were confirmed through detailed studies of transmission electron microscopy. The relationships of the domains, doping concentration, and grain size were determined, and their effects on the ionic conductivities were examined. It was concluded that the domains were formed via the segregation of Yb cations so that they could trap the oxygen vacancies and lower the conductivity. Furthermore, the development of the domains, which depends on the doping concentration and grain size, can affect the doping concentration and grain-size dependencies of the conductivity.