Dielectric relaxations in the Ca-doped CeO2 system

Abstract

Dielectric relaxations were investigated for 10 mol% Ca-doped CeO 2 (Ce0.9Ca0.1O2-δ) having a cubic fluorite-type structure, which is a typical oxide-ion conductor. The dielectric constants (ε′r) showed anomalously large values at low frequencies and high temperatures. Numerical analysis of the frequency dependence of ε′r clarified that the large ε′r originated from superimposition of both the electrolyte-electrode interfacial and Debye-type polarizations. The ac conduction dispersion was also successfully explained by the interfacial and Debye-type polarizations. Two kinds of Debye-type relaxations observed were ascribed to defect associates, (Ca″ce-V..o) which have different distances between the dopant and the oxygen vacancy.