Synthesis of chain-like and core-shell spherical Fe3O4@SiO2 complex

Linear chain-like and core shell spherical Fe3O4@SiO2 complex particles were synthesized through StOber process under magnetic stirring, using well-dispersed Fe3O4 particles, PEG-6000 as surfactant and template-driven agents. The length of Fe3O4@SiO2 complex is 1.1 mu m and the average diameter of Fe3O4@SiO2 complex is about 200 nm. The synthesis conditions of the product were studied, and the morphology and properties of the products were characterized by TEM, SEM, X-ray powder diffraction, FT-IR, EDS. The results show, the formation of Fe3O4@SiO2 complex involves the initial hydrolysis of TEOS, formation of Fe-O-Si bond and finally condensation of Si-O-Si. PEG-6000, TEOS and ammonia in the right amounts are both beneficial to formation of Fe3O4@SiO2 with good core shell, and distinct chain-like structure, which leads to the synthesized product having a good magnetic response capability, whereas long chain PEG-6000 can play a role as guide agent. The XRD pattern of Fe3O4@SiO2 complex both has characteristic peaks of Fe3O4, and also has a characteristic peak of amorphous silica, in a good agreement with IR and EDS results.