Relationship between oxide-ion conductivity and dielectric relaxation in Sm-doped CeO 2

Abstract

The relationship between electrical conduction and dielectric relaxation was investigated for 20 at.% Sm doped CeO 2 (Ce 0.8Sm 0.2O 2− δ ), which is a typical oxide-ion conductor. Numerical calculation clarified that the anomalously large dielectric constant ( ε r′) originated from the superimposition of both Debye-type polarization and interfacial polarization between electrolyte and electrode. Two kinds of the Debye-type relaxation appeared at and above 673 K, which were assigned to defect associates, (Sm Ce′–V O ) and (Sm Ce′–V O –Sm Ce′) x . The Debye-type polarization was also confirmed by analyzing the dielectric loss factor ( ε rʺ). Ac conductivity ( σ ac) in high temperature and high frequency regions agreed with dc conductivity ( σ dc), while the dispersion of σ ac was ascribed to the Debye-type polarizations.