Structural, dielectric and AC conductivity studies of Zn substituted nickel ferrites prepared by combustion technique

A series of zinc doped nickel ferrites having the chemical formula Ni_1−xZn_xFe₂O₄ [x = 0.0, 0.25, 0.50, 0.75, 1.0] were synthesized by combustion method. The powder X-ray diffraction results confirm the formation of single phase cubic spinel structure. The lattice parameter was found to increase from 8.348 to 8.443 Å with increase in the Zn content. Average crystallite size calculated using Debye–Scherrer equation and Williamson–Hall plots confirms the nano crystalline nature of the samples. The EDAX analysis indicates the correct elemental composition of the synthesized powders. Fourier transform infrared spectra show the characteristic peaks of Ni–Zn spinel ferrites. The morphological features of the powder were examined by SEM and reveal the fine crystalline nature of the powder. A systematic study on the dielectric properties such as dielectric constant (ɛ′), dielectric loss tangent (tan δ) and AC conductivity (σ_ac) were investigated as a function of Zn content and frequency in the range from 100 Hz to 1 MHz at room temperature. Complex impedance behavior was explained by means of the cole–cole plot.