Investigation of Structural and Magnetic Properties in Aluminium-Substituted Cobalt-Zinc Ferrite Metal Oxides

In recent years, spinel ferrites have attracted considerable research interest due to their distinctive structural, magnetic and electrical properties, positioning them as promising candidates for a wide range of advanced technological applications. Aluminium substituted cobalt-zinc spinel ferrite with chemical composition Co0.2Zn0.8Fe2-xAlxO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by the sol-gel auto-combustion technique. The structural properties of the synthesized ferrites were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and magnetic properties were analyzed by vibrating sample magnetometry (VSM). XRD results confirmed the formation of a single-phase cubic spinel structure with a space group Fd-3m and particle sizes were in the range of 12 nm to 72 nm. The FTIR spectra showed distinct absorption bands around 570 cm⁻¹ and 450 cm⁻¹, which were attributed to the stretching vibrations of metal-oxygen bonds at tetrahedral and octahedral sites, respectively. The magnetic studies demonstrated a progressive reduction in magnetic properties with increasing aluminium substitution concentration, culminating in the observation of superparamagnetic behavior at higher substitution levels. This behaviour is indicative of the significant influence of aluminium substitution on the magnetic characteristics of the material.