AC-electrical conductivity, magnetic susceptibility, dielectric modulus and impedance studies of sol-gel processed nano-NiMgZn ferrites

The Ni0·2Mg0.8-xZnxFe2O4 (x = 0.0–0.8) (NMZF) nanomaterials were prepared via sol-gel technique followed by three calcination temperatures (T) of 400, 450 and 500 °C/5 h. The X-ray diffraction patterns of NMZF showed the single phase cubic spinel structure. The nanosized grains were detected using the field emission scanning electron microscope (FESEM) images. The results showed that the larger concentration of zinc established the maximum grain size (86.9–119.6 nm), wherein the predominant grain boundary creeping mechanism was observed. The electric (Te) and magnetic (Tm) transition temperatures obtained using the Arrhenius and magnetic susceptibility-temperature (χ-T) plots revealed that the transition temperatures were decreased with increase of Zn-content. The Tm (195–250 °C) values obtained for x = 0.8 sample (high Zn-content) at 400 and 500 °C temperatures indicated the decrease of magnetic exchange interactions as well as the weakening nature of ferrimagnetic behavior. Furthermore, in order to identify the diffusion of carriers from one state to other state, the activation energies were calculated using the Arrhenius plots for x = 0.0–0.8 contents. In addition, the frequency and temperature dependence of dielectric modulus and impedance parameters was studied for addressing the relaxation mechanism, grain and grain boundary effect in the electrical conduction mechanism of NMZF. The Nyquist plots showed the presence of non-Debye relaxations for all samples. Besides, the same plots attributed the semiconducting nature at high temperatures due to having the complete semicircular arcs. •NiMgZn ferrite nanomaterials were prepared via sol-gel technique.•XRD patterns confirmed single phase cubic spinel structure.•The Te and Tm values were decreased with increase of Zn-content.•X = 0.8 showed conduction mechanism via grain and grain boundary.•Nyquist plots showed non-Debye relaxations for all samples.