Dielectric behavior of ZnFe ₂ O ₄ synthesized by hybrid route

ZnFe 2 O 4 nanoparticles were successfully synthesized using a sol–gel auto-combustion technique followed by sintering, forming a single-phase spinel cubic structure confirmed by XRD. The average crystallite size was estimated to be 30[Formula: see text]nm, while SEM analysis revealed a nonuniform grain morphology, with grain sizes ranging from approximately [Formula: see text]m to [Formula: see text]m. Grain size distribution, measured using ImageJ software, showed a Gaussian profile with a mean grain diameter of [Formula: see text]m and a standard deviation of [Formula: see text]m, indicating a moderately broad distribution. EDS spectra confirmed the presence of only Zn, Fe and O elements, verifying the high purity of the synthesized ZnFe 2 O 4 nanoparticles. FTIR spectroscopy further confirmed the formation of the spinel ferrite phase, exhibiting two characteristic absorption bands at 531.9[Formula: see text]cm[Formula: see text] and 420.7[Formula: see text]cm[Formula: see text], corresponding to Fe–O stretching vibrations at tetrahedral sites and Zn–O vibrations at octahedral sites, respectively. UV–Vis analysis revealed a direct optical band gap of 1.89[Formula: see text]eV, consistent with the semiconducting nature of ZnFe 2 O 4 . Dielectric measurements showed that both the dielectric constant and dielectric loss decrease with increasing frequency and increase with temperature, indicating typical dipolar relaxation behavior. Impedance spectroscopy revealed negative temperature coefficient of resistance (NTCR) behavior and allowed differentiation between grain and grain boundary contributions via Nyquist plots. Overall, this study presents a comprehensive structural, morphological, optical and dielectric characterization of ZnFe 2 O 4 synthesized by a hybrid sol–gel/solid-state route, filling a critical gap in the literature by providing detailed insights into its temperature-dependent dielectric behavior. These findings support its potential application in electronic, capacitive and sensor devices.