Conduction and dielectric relaxations in PVA/PVP hydrogel synthesized cerium oxide

Dielectric relaxation at higher frequencies with dc conductivity contribution is observed in PVA/PVP hydrogel synthesized Nano-crystalline Cerium oxide (CeO₂), which is a typical oxygen ion conductor. The material is characterized using XRD, FTIR, Raman spectroscopy, SEM, TEM, UV-Vis and Impedance spectroscopy. Impedance spectroscopic data of the material are studied with combined Cole-Cole type conduction and dielectric relaxations and the results revealed that the material possesses two types of dipoles, pinned dipole and free dipole. The electrical parameters extracted from the analysis are found to be independent of ac data representations. The dc conductivity σ_c, conduction relaxation time τ_c and dielectric relaxation time τ_d show Arrhenius behavior. Conduction process follows Barton–Nakajima–Namikawa (BNN) relation and dielectric process follows fractional Debye–Stokes–Einstein (DSE) equation. Time-temperature scaling of complex impedance data suggests that the conduction mechanism is slightly temperature dependent. Intrinsic defects created in the material and hopping of charge carriers generate a combined relaxation in the material. (paper)