Synthesis and characterization of Fe_3O4_-TiO_2 core-shell nanoparticles

摘要

Composite core-shell nanoparticles may have morpho-structural, magnetic, and optical (photolumi-nescence (PL)) properties different from each of the components considered separately. The properties of Fe_3O_4-TiO_2 nanoparticles can be controlled by adjusting the titania amount (shell thinness). Core-shell nanoparticles were prepared by seed mediated growth of semiconductor (TiO_2) through a modified sol-gel process onto preformed magnetite (Fe_3O_4) cores resulted from the co-precipitation method. The structure and morphology of samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), and high resolution-TEM respectively. X-ray photoelectron spectroscopy was correlated with ICP-AES. Magnetic measurements, optical absorption spectra, as well as PL spectroscopy indicate the presence of a charge/spin transfer from the conduction band of magnetite into the band gap of titania nanocrystals. The process modifies both Fe_3O_4 and TiO_2 magnetic and optical properties, respectively.