Relationship between Oxide-Ion Conduction and Dielectric Properties of Gd2Zr2O7 Having a Fluorite-Type Structure

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The relationship between electrical conduction and dielectric properties was investigated for the oxide-ion conductor Gd2Zr2O7 having a fluorite-type structure. Computer simulation clarified that the anomalously large dielectric constant ($\varepsilon_{\text{r}}{}'$) was successfully explained by the superposition of the Debye-type polarization and the electrolyte–electrode interfacial polarization. Two Debye-type relaxations were observed at 673 K and above. The lower-frequency relaxation was ascribed to the dopant–vacancy associate, (GdCe$'$–VO••–GdCe$'$), and the higher one to the long range migration of oxide ions on the basis of the discussions of both the activation energies and the relaxation frequencies. The frequency dependences of both the ac conductivity ($\sigma_{\text{ac}}$) and the loss tangent ($\tan\delta$) were also successfully explained using the dielectric parameters of the Debye-type dopant–vacancy associates.
2008-07-25