Synthesis and magnetic properties of PVP capped Ni0.6Zn0.2Sb0.2Fe2O4 nanoferrites

The co-precipitation method was used to synthesize Ni_0.6Zn_0.2Sb_0.2Fe₂O₄ nanoparticles capped with different concentrations of Polyvinylpyrrolidone (PVP) (0-2.414 mM). X-ray powder diffraction (XRD) determined that the addition of the PVP capping agent caused an increase in the weight% of the main phase (Ni_0.6Zn_0.2Sb_0.2Fe₂O₄) and a decrease in the weight% of the secondary phase (hematite phase (α-Fe₂O₃)) in all samples compared to P0 (0 mM). The P7 sample (0.3451 mM) registered the highest percentage of the main phase (98.48%) and the lowest percentage of the secondary phase (1.52%). The increase in PVP concentrations caused a decrease in the porosity. Transmission electron microscopy (TEM) revealed the formation of spherical-shaped nanoferrites. Also, it confirmed that PVP improved the shape of the particles and tended to slightly increase their size with the P7 sample having the greatest particle size (18.320 nm). The selected area electron diffraction (SAED) patterns proved the formation of nanoferrites of polycrystalline nature. Energy dispersive X-ray (EDX) proved the purity of the synthesized nanoferrites. The oxidation state (Ni²⁺, Ni³⁺, Zn²⁺, Sb³⁺, Fe^3+, and O²⁻) and the elemental composition of the synthesized nanoferrites were examined using X-ray photoelectron spectroscopy (XPS). Moreover, the functional groups were analyzed via Fourier transform infrared spectroscopy (FTIR). Raman spectroscopy technique identified the presence of four phonon modes: two A_1g and two F_2g. The vibrating sample magnetometer (VSM) proved that all samples attained a weak ferromagnetic behavior, which was modeled by the Law of approach to saturation. Sample P7 exhibited the highest saturation magnetization value of 43.968 emu/g, making it the best sample for magnetic applications and recording devices.