Study of structural, dielectric properties of ZnFe₂O₄: effect of thermal annealing

Abstract We report structural, dielectric properties of sol-gel auto-combustion-synthesized ZnFe 2 O 4 nano-ferrites (grain-size: 53.43 - 64.81 nm), and study the effect of thermal annealing on structural dielectric properties by X-ray diffraction (XRD), dielectric measurements. Results show that thermal-annealing shows: i) an increase of lattice parameter (a exp. ), and on B-site: there is an increase of Zn 2+ population with concurrent decrease of Fe 3+ ions, ii) alterations of inversion-degree from 0.18 to 0.32, strengthening of A-O-B, A-O-A interactions, accompanied by a weakening of B-O-B super-exchange-interaction, iii) decrease of theoretical magnetization at 0 K (M s(th) ), iv) with increasing frequency, real-imaginary components (ε', ε'') of dielectric constant, and loss-tangent decreases, v) that at higher frequencies, ac conductivity (σ ac ) shows a significant increase and exhibited a power law dependence, suggesting a typical of charge transport assisted by a hopping or tunneling processes. Results also reveal that polarizability strength decrease with annealing temperature, and correlated-barrier-hopping remains the dominant mechanism for conduction. Cole-Cole plots (ε', ε''), corresponding complex impedance (Z', Z'') data are indicative of the growing influence of grain boundaries on the dielectric properties for the studied samples. Observed improved-response of σ ac , recommends the potential-applications of the studied samples in high-frequency device applications.