Relationship between Dielectric Properties and Oxygen Defect Structure of Nondoped CeO2

概要

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The dielectric properties of CeO2, which was annealed at 1273 K in O2, air, and Ar atmospheres for the as-sintered specimens, were investigated in the temperature range from 673 to 1073 K. The frequency dependences of dielectric constant ($\varepsilon_{\text{r}}{}'$) and dielectric loss factor ($\varepsilon_{\text{r}}{}''$) were successfully explained by Debye-type polarization model. The observed values of dielectric loss tangent ($\tan\delta$) and ac electrical conductivity ($\sigma_{\text{ac}}$) agreed with the values calculated using the dielectric parameters estimated from the analyses of $\varepsilon_{\text{r}}{}'$ and $\varepsilon_{\text{r}}{}''$. It was found that the dielectric parameters such as Debye-type polarization ($\varepsilon_{\text{r}o1}$), relaxation frequency ($\omega_{o1}$), and ac conductivity ($\sigma_{\text{ac}}$) increased with increasing oxygen vacancy concentration, which depends on the oxygen partial pressure in the annealing atmospheres.
2009-12-25