Structural, Spectral, and Magnetic Investigations of Zn and Co Incorporated NiFe₂O₄ Spinel Ferrites

Abstract

This study investigates the structural, spectral, and magnetic properties of zinc and cobalt doped nickel ferrite (NiFe₂O₄) nanoparticles synthesized via sol-gel auto-combustion method. Samples with compositions Ni₁₋ₓZnₓFe₂O₄ and Ni₁₋ₓCoₓFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8) were systematically analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Mössbauer spectroscopy. XRD analysis confirmed the formation of single-phase cubic spinel structure for all compositions with crystallite sizes ranging from 24-42 nm. FTIR spectra revealed characteristic tetrahedral and octahedral metal-oxygen vibrations. Magnetic measurements demonstrated that zinc substitution decreased saturation magnetization and Curie temperature due to its diamagnetic nature, while cobalt doping enhanced magnetic anisotropy and coercivity. The cation distribution analysis indicated preferential site occupancy of Zn²⁺ at tetrahedral sites and Co²⁺ at octahedral sites, significantly influencing the magnetic exchange interactions. This comparative study provides crucial insights into tailoring the magnetic and structural properties of nickel ferrite nanoparticles through strategic doping for diverse technological applications.