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Relationship between Dielectric Properties and Oxygen Defect Structure of Nondoped CeO2

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 (εr') and dielectric loss factor (εr'') were successfully explained by Debye-type polarization model. The observed values of dielectric loss tangent (tan δ) and ac electrical conductivity (σac) agreed with the values calculated using the dielectric parameters estimated from the analyses of εr' and εr''. It was found that the dielectric parameters such as Debye-type polarization (εro1), relaxation frequency (ωo1), and ac conductivity (σac) increased with increasing oxygen vacancy concentration, which depends on the oxygen partial pressure in the annealing atmospheres.