Dielectric Relaxations in the Ce1-xYbxO2-δ System

The dielectric properties of Yb-doped CeO2 (Ce1-xYbxO2-δ) which is an oxide-ion conductor were investigated. Numerical analysis of the frequency dependences of dielectric constants ($\varepsilon'$) and dielectric loss factors ($\varepsilon''$) revealed that the dielectric characteristics can be successfully explained by the superimposition of both Debye-type polarization due to dopant-vacancy associates and electrolyte–electrode interfacial polarization. The temperature response of the dielectric properties was less active than that of the Sm- or Nd-doped CeO2 systems, which have higher oxide-ion conductivity than the present system. Three types of Debye-type polarizations were observed. The first polarization at the highest-frequency region was ascribed to a long-range migration of oxygen vacancies. The second and third polarizations at the lower-frequency region were ascribed to the dopant-vacancy associates. The observed values of $\sigma_{\text{ac}}$ and $\tan\delta$ were also successfully explained using the dielectric parameters that were obtained from the numerical analysis of dielectric constant.