Effect of ultrasonic treatment on dispersibility of Fe3O4 nanoparticles and synthesis of multi-core Fe3O4/SiO2 core/shell nanoparticles

Ultrasonic treatment was employed to improve the dispersibility of the Fe3O4 nanoparticles dispersed in aqueous solutions. Electrophoresis and XPS spectra indicate that the ultrasonic treatment can induce the generation of chemisorbed hydroxyl groups and the oxidation of Fe2+ ions on the surface of the magnetic nanoparticles, thus resulting in improved dispersibility of the magnetic nanoparticles. After growth of silica protection layers on the Fe3O4 nanoparticles with different times of ultrasonic treatment, Fe3O4/SiO2 core/shell nanoparticles with different amounts of the magnetic cores were successfully prepared.