Spinel ferrite nanocomposites of Ni1–xZnxFe2O4 (x = 0.25 and 0.75) were synthesized by sol-gel auto-combustion and annealed between 250°C and 1000°C. A single-phase spinel structure was found through X-ray diffraction (XRD). The crystallite size is in the range of 17.55–66.98 nm, and lattice parameters are in the range of 8.351–8.434 Å. X-ray analysis revealed a slight shift of the peaks towards shorter angles when the zinc concentration increased from 0.25 to 0.75. XRD measurements revealed the metal ion distribution in the spinel ferrite system. For each sample, XRD data were used to compute structural characteristics such as lattice spacing, lattice constant, crystallite size, oxygen position parameter, tetrahedral and octahedral ionic radii, and bond lengths. Energy dispersive spectroscopy (EDS) spectra and field emission-electron scanning microscope (FESEM) were used to evaluate the elemental content and morphology. EDS analysis confirmed the presence of expected elements in the samples and confirmed the high doping rate of more than 180% of Zn ions in Ni ferrite. The evaluated particle sizes were determined to be 79.2 and 118.4 nm for zinc content of 0.25 and 0.75, respectively. The nearly spherical shape of the nanoparticles was shown in the transmission electron microscope (TEM). The magnetic moment, remanent, coercivity, and saturation magnetization were calculated by using vibrating sample magnetometer (VSM) results. The saturation magnetization magnitudes showed the influence of cation distribution.

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The sol-gel auto-combustion approach was used to create Ni0.4M0.2Zn0.4Fe2O4 (M=Ni2+, Mg2+, and Co2+) nanoparticles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), and an inductance-capacitance-resistance (LCR) meter were used to analyse the samples’ structural, elastic, and electrical properties. In all samples, the XRD patterns obtained indicated the formation of a monophasic cubic spinel structure with no identifiable impurity phase, which was supported by EDS investigations. The introduction of substituting ions, specifically Mg2+ and Co2+, into Ni-Zn ferrite nanoparticles results in an increase in the lattice parameter. The lattice parameter for Ni-Zn is 8.377Ao, while for the substituted nanoparticles it is 8.389 and 8.388 Ao for Mg2+ and Co2+ respectively. Additionally, the crystallite size of the substituted nanoparticles increases to 46.57 nm from 40.75 nm for Ni-Zn. However, the X-ray density of the substituted nanoparticles decreases to 5.180 and 5.337 g/cm3 for Mg2+ and Co2+ respectively, from 5.358 g/cm3 for Ni-Zn. The elastic parameters, such as the Young's modulus, Debye temperature, bulk modulus, and rigidity modulus, were calculated. The good elastic characteristics of Ni-Zn ferrite were confirmed and may be explained by the lower lattice parameter values and smaller crystallite sizes. Temperature and frequency effects on dielectric behaviour and AC electrical conductivity (σAC) were investigated. At ambient temperature, the dielectric characteristics, specifically the dielectric constant (ε') and loss tangent (tanδ), were computed over a frequency range of 100 Hz to 2 MHz. The compositions display normal dielectric properties, which are attributed to the interfacial polarisation following the Maxwell-Wagner model. The AC conductivity of nanoparticles was shown to decrease when Mg2+ and Co2+ were substituted into Ni-Zn ferrite. Furthermore, the AC conductivity diminishes with decreasing frequency, which is a sign of ionic conductivity. There was a direct relationship between the temperature and the values of ε', tanδ, and σAC for different ions.