Anomaly diffuse and dielectric relaxation in strontium doped lanthanum molybdate

The dielectric properties of the La_2-xSr_xMo ₂O_9-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 E_a 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.