A novel non-thermal process of TiO2-shell coating on Fe3O4-core nanoparticles

In this work magnetite (Fe3O4) nanoparticles coated with titanium dioxide (TiO2) were prepared by a novel non-thermal method. In this method, magnetite and pure TiO2 (anatase) nanoparticles were individually prepared by the sol–gel method. After modifying the surface of magnetite nanoparticles by sodium citrate, titanium dioxide was coated on them without using conjunction or heat treatment to obtain Fe3O4:TiO2 core–shell nanoparticles. XRD, EDX, SEM, TEM and VSM were used to investigate the structure, morphology and magnetic properties of the samples. The average crystallite size of the powders was measured by Scherrer's formula. The results obtained from different measurements confirm the formation of Fe3O4:TiO2 core–shell nanoparticles with a decrease in saturation magnetization. Hysteresis loops of the core–shell nanoparticles show no exchange bias effects, which confirms that there is no interaction or interdiffusion at the interface.

► Magnetite (Fe3O4) nanoparticles coated with TiO2 as core–shell nanostructure.
► TiO2 (anatase) structure and magnetite nanoparticles have been successfully prepared individually by a sol–gel method.
► Magnetic measurements showed the superparamagnetic behavior for pure Fe3O4 nanoparticles.
► Spherical morphology of the core–shell nanoparticles was found from the SEM micrograph.