Structural, morphological and dielectric characteristics of (Ni_0.5Zn_0.5Fe₂O₄)_1-x/(MWCNTs)_x nanocomposites for energy storage devices

Ni_0.5Zn_0.5Fe₂O₄ (NiZnF) nanoparticles were synthesized using an environmentally friendly and economically cost-effective method, sol-gel auto-combustion and subsequently functionalization with multi-wall carbon nanotube using ultrasonication assist method. A series of samples was prepared with compositional formula of (NiZnF)_1-x/(MWCNTs)_x nanocomposites at x = 0 to 20 wt% with step size of 5 wt%. The aim of this study is to investigate the influence of MWCNT on structural, morphological and dielectric properties of NiZnF ferrites and explore their potential for dielectric energy storage application. X-ray diffraction (XRD) analysis was used to study the structural parameters that confirmed the single-phase cubic spinel structure of the synthesized samples without detectable secondary phases. Transmission electron microscopy (TEM), a more advanced techniques were utilized to confirm the structural parameters from observed by XRD analysis. TEM's results revealed the successful dispersion of ferrite nanoparticles in MWCNT. Fourier transform infrared (FTIR) spectroscopy verified the characteristic metal-oxygen vibrations associated with tetrahedral and octahedral sites of the synthesized spinel ferrites lattice and revealed the interaction between carbon nanotube and ferrite phase. Such type of linkage/interaction may affect the dielectric and impedance parameters that were studied over a frequency range from 25 Hz to 2 MHz. Impedance spectroscopic analysis provided a decrease in value of impedance and increasing AC conductivity due to increasing conducting nature of MWCNTs. This significant behavior demonstrated a development of continuous conductive network due to strong linkage between the spinel ferrites nanoparticles and MWCNTs. Moreover, due to strong dielectric nature at low frequency with significant effect MWCNTs contents is responsible for the materials that could be used for the energy storage applications.