Solvothermal synthesis of magnetic Fe 3O 4 microparticles via self-assembly of Fe 3O 4 nanoparticles

Abstract

Ferromagnetic Fe 3O 4 nanoparticles were synthesized and then self-assembled into microparticles via a solvothermal method, using FeCl 3·6H 2O as the iron source, sodium oleate as the surfactant, and ethylene glycol as the reducing agent and solvent. The obtained Fe 3O 4 microparticles were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and vibrating sample magnetometer (VSM). The size and morphology of the particles were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The Fe 3O 4 microparticles of nearly monodisperse diameters, controllable in the range of 120–400 nm, consist of assemblies of Fe 3O 4 nanoparticles with a diameter of 22 nm. The effects of reaction time, amount of surfactant and NaAc on the products were discussed. Interestingly, by using the pre-synthesized Fe 3O 4 microparticles as the growth substrates, spherical and smooth-looking Fe 3O 4 microparticles with average diameter of 1 μm were obtained. A plausible formation process was discussed.