Magnetic and optical properties of Cu1−xZnxFe2O4 nanoparticles dispersed in a silica matrix by a sol–gel auto-combustion method

Cu1−xZnxFe2O4/SiO2 (CZF/SiO2) (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) nanocomposites were synthesized by a citric acid assisted sol–gel process and a modified Stöber method. Particle formation and evolution of the structural, morphological, optical and magnetic properties were investigated by Thermal analysis (TGA), X-ray powder diffractometry (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM)), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectra (DRS), and magnetic susceptibility measurements (VSM). Optical properties of Cu–Zn ferrite nanoparticles (NPs) were improved by using silica (SiO2) shell. CZF/SiO2 nanocomposites were evaluated for their magnetic and optical characteristics. The direct optical band gap (Eg) value was calculated as 1.70 eV. The Eg of CZF/SiO2 nanocomposites is found to increase as the Zn content rises. Moreover, silica coating enhances the band gap of the nanocomposites. These properties of CZF/SiO2 nanocomposites make them promising candidates for magneto-optical nano-device applications.