Fabrication of monodisperse magnetic Fe3O4-SiO2 nanocomposites with core-shell structures

Monodisperse Fe3O4-SiO2 nanocomposites with core-shell structures have been designed and synthesized successfully in an organic phase using a two-step synthetic strategy. The obtained materials were characterized in detail by X-ray diffraction, transmission electron microscopy, and a vibrating sample magnetometer. The analytical results showed that the obtained Fe3O4-SiO2 nanoparticles possess core-shell nanostructures, high monodispersity, and uniform size and shape. The core, shell, and their combination are all in nanoscale. The average particle size of the resultant Fe3O4-SiO2 nanocomposites is about 19 nm, and the average thickness of the nanocomposite shells is about 6 nm. Furthermore, the final Fe3O4-SiO2 core-shell nanoparticles present good magnetic properties. A proposed formation mechanism of monodisperse Fe3O4-SiO2 nanocomposites with core-shell structure is also presented in this paper, which is very important for the rational construction, design, and synthesis of other monodisperse core-shell nanocomposites with uniform size and shape.