Synthesis and characterization of magnetic nanoparticles of cobalt ferrite coated with silica

There are several methods available for magnetic nanoparticles (MNP) synthesis, and in this study the coprecipitation method is employed. The cobalt ferrites (CF) were prepared using aqueous solutions of Co2+ and Fe3+ chloride with a stoichiometry proportion of Co:Fe = 1:2. Thus, the aging temperatures were 27, 27/98, 60, 80 and 98 ºC, during which the precipitation occurred at 27 °C and the aging one at 98 °C for the FC27/98 sample. As a result, the study showed that a single crystal phase material was obtained at the aging temperature of 98 °C during 1 h and with a mean particle size of 42 nm ± 7.4 nm and degree of polydispersity of 18%. The FC98/SiOH coated nanoparticle had a surface area of 11 m2 g-1, saturation magnetization of 10.05 emu g-1 a mean particle size of 773.4 nm ± 131.1 nm and a degree of polydispersity of 17 %. It was possible to confirm that it had a silica coating of cobalt ferrite nanoparticles by DRIFT and EDX indicated the presence of silica.