In this study, Zn0.5Co0.5Fe2O4 spinel nanoferrites were synthesized via a conventional sol–gel combustion method at varying calcination temperatures (as-burnt, 500, 600, and 700 °C). Nanocomposites of the formula 100-x(Zn0.5Co0.5Fe2O4) + x(SiO2) were then prepared by substituting these ferrite nanopowders with amorphous SiO2 nanoparticles at different concentrations (x = 0, 2, 4, 6, and 8 wt.%). This blend was homogenized in a ceramic mortar for one hour for uniform component distribution. X-ray diffraction confirmed the formation of Zn0.5Co0.5Fe2O4 nanoferrite with the \(Fd\overline{3 }m\) space group, showing crystallite size increases from 5.21 nm at as-burnt to 46.31 nm at 700 °C. SiO2 substitution increased crystallite sizes from 36.25 nm to 49.05 nm as SiO2 content rose from 0% to 8 wt.% in nanoferrite samples calcined at 600 °C. Fourier Transform Infrared Spectroscopy analysis identified absorption bands characteristic of the cubic spinel structure in both calcined and SiO2-substituted samples, showcasing structural adjustments due to calcination and SiO2 substitution. Field Emission Scanning Electron Microscopy revealed that particle sizes increased from 13.23 nm to 51.00 nm with calcination and further changed with SiO2 incorporation, affecting the ferrite matrix microstructure and resulting in particle size increases from 42.77 nm to 52.92 nm with 2% to 8% SiO2. Magnetic properties generally improved, displaying increased saturation and remanent magnetization, albeit with decreasing coercivity with temperature except at 700 °C. However, SiO2 substitution led to reduced saturation and remanent magnetization and varied coercivity, peaking at a 4% SiO2 level. These structural and ferromagnetic changes suggest significant potential for biomedical applications in the nanocomposites.
