Zinc-doped cobalt ferrite nanoparticles: modified sol-gel synthesis, multifunctional properties, and cytotoxicity evaluation

The present work explores physical characteristics of zinc doped cobalt ferrite nanostructures. Co_1-xZn_xFe₂O₄(x = 0.0, 0.3, 0.5, 0.7, 1) nanoparticles were synthesized by a modified sol-gel method. The Rietveld refinement of the X-ray diffraction data confirms the cubic spinel structure of the ferrite phase in the Fd-3m space group. The crystallite size of the sample varies between 52–16 nm, and an increase in lattice parameter is noticed with zinc doping. The X-ray densities are also calculated. It is discovered that when zinc concentration rises, size falls, dislocation density rises, and packing factor decreases. At varying Zn ion concentrations, the tolerance factor (T) for Co_1-xZn_xFe₂O₄ ferrites is around 1, indicating the cubic spinel structure of ferrites. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX) were used for morphological and elemental composition studies of the synthesized samples. Frequency-dependent dielectric constant, dielectric loss, and ac conductivity have been investigated. The dielectric constant values were found to be in the range of high dielectric constant, so these materials were the promising candidates for technological applications such as gate dielectrics, capacitor dielectrics, and epitaxial dielectrics, etc. The bandgap energy calculated from UV-Visible analysis increases with zinc ion concentration (2.95–4.33 eV). The zinc substituted cobalt ferrite nanoparticles with tunable bandgap as well as dielectric properties can be easily prepared by the modified sol-gel method. In the present study, significant cytotoxicity was exhibited by the cobalt ferrite nanoparticles. The magnetic hysteresis (M-H) loops study shows the ferromagnetic nature of all the samples. The maximum saturation value M_S was obtained for Co_0.5Zn_0.5Fe₂O₄ sample which is 73.72 emu/g. The value of the remanent magnetization and coercive field of Co_0.3Zn_0.7Fe₂O₄ and ZnFe₂O₄ nanoparticles indicate its superparamagnetic nature.

Graphical Abstract