Dielectric Relaxations in the Ce1-xSmxO2-δ System

Dielectric relaxations were investigated for the solid-solution system Ce1-xSmxO2-δ(0.0≦x≦0.5), which is a typical oxide-ion conductor. The dielectric constants showed anomalously large values at low frequencies and high temperatures. Computer simulation clarified that the anomalously large dielectric constant (εr′) originated from the superimposition of both Debye-type polarization and interfacial polarization between electrolyte and electrode. Two kinds of Debye-type relaxation observed were ascribed to defect associates, (SmCe′-VO••)• and (SmCe′-VO••-SmCe′)×. The Debye-type polarization was also confirmed by analyzing the dielectric loss factor (εr″). When the oxide-ion conductivity decreased in the heavy Sm-doped samples, the Debye-type polarization also disappeared, suggesting that ordering of oxygen vacancy suppressed the electric field response of Debye-type polarization.