Microstructural, magnetic, and optical properties of nickel-doped spinel zinc ferrite nanoparticles

This study focuses on the synthesis of nickel-substituted zinc ferrite nanoparticles, Zn1_ xNixFe2O4, via the sol-gel method and examines how nickel substitution influences their structural, magnetic, and optical properties. The lattice constant of the nanoparticles, which varied from 8.4296 & Aring; to 8.4212 & Aring;, decreased as the nickel concentration increased. Scanning electron microscopy (SEM) was employed to examine the morphology, revealing grain sizes between 46 and 53 nm, while energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing nearly spherical nanoparticles containing all the constituent elements. The magnetic properties were analyzed using a vibrating sample magnetometer (VSM), which highlighted significant differences between the theoretical and experimental magnetic moments, indicating the presence of Yafet-Kittel magnetic ordering in the system. The saturation magnetization was enhanced by Ni+2 ions, reaching a maximum value of 23.864 emu/g. This enhancement makes the nickel-substituted zinc ferrite nanoparticles suitable for applications in data recording media and magnetic resonance imaging. Additionally, the values of the magnetic crystalline anisotropy constant, initial permeability, effective anisotropy constant, and anisotropic field of the synthesized samples were estimated. The optical properties of the synthesized samples were evaluated using UV-visible spectroscopy, and the band gap was determined through diffuse reflectance spectroscopy (DRS). The optical bandgap of pure zinc ferrite was measured to be 2.26 eV, and it decreased with increasing nickel concentration in the nanoparticles.