Anomaly diffuse and dielectric relaxation in strontium doped lanthanum molybdate

Highlights: ► The anomaly diffuse and dielectric relaxation behaviors are fitted by the Cole–Cole approach. ► The peak in the LSMO is corresponding to different oxygen ion diffusion process. ► We first give better explanation about the strange conductivity change caused by doping. ► The oxygen ion diffusion is due to a combination of the dipolar relaxation and the motion of ions. -- Abstract: The dielectric properties of the La2−xSrxMo2O9−δ (x = 0–0.2) ceramics were investigated in the temperature range of 300–800 K. Dielectric measurement reveals that two dielectric anomalies, associated with the oxygen ion diffusion, exist in frequency spectrum with x = 0.5. The broad dielectric peaks in tan δ(ω) can be well fitted by a modified Cole–Cole approach. When x = 0.1, only one dielectric relaxation peak is observed, corresponding to different oxygen ion diffusion processes, as distinct from the only relaxation peak in the pure La2Mo2O9. The relaxation parameters τ0, the dielectric relaxation strength Δ, and the activation energy Ea were obtained. The result of this work shows that, the conductivity change caused by doping between the two phases is due to the combination of the dipolar effects and motion of ions.