Effect of Mn2+ doping and SiO2 coating on magneto-optical properties of CoFe2O4 nano-particles

Co1−xMnxFe2O4 (x = 0.2, 0.4, 0.6, 0.8, 1.0) magnetic nanoparticles were prepared using a modified citrate gel method and fired at 500 °C for 2 h. The modified Stober method was used for coating the magnetic nanoparticles with a silica shell. The effects of Mn2+ substitution and the method of preparation on the formation of crystalline phases, particle size, morphology and the optical and magnetic properties of the synthesized materials were investigated by XRD, SAED, HR-TEM, EDX, UV/VIS double-beam spectrophotometry and vibrating sample magnetometry. The average crystallite size of the synthesized nanoparticles was 18.6–43.9 nm. The maximum value of saturation magnetization (Ms) achieved was 65.668 emu/g for Mn0.2Co0.8Fe2O4 nanoparticles. Diffuse reflectance increased with an increase of Mn2+content and SiO2 shell. These coated magnetic nanoparticles are promising materials for application to magnetic sensors and biomedical nanodevices.