Preparation and,characterization of shuttle-like α-Fe2O3 nanoparticles by supermolecular template

Shuttle-like alpha-Fe2O3 nanoparticles have been successfully synthesized via a new soft-template route using polyethylene glycol (PEG) as polymer, cetyltrimethylammonmm bromide (CTAB) as surfactant and FeCl(3)(.)6H(2)O as iron source materials. Meanwhile, spherical alpha-Fe2O3 nanoparticles are also fabricated under the similar conditions without surfactant and polymer. The resultant products are characterized by means of thermalgravimetric analysis (TGA), powder X-ray diffraction (XRD), infrared (IR) spectroscopy, transmission electron micrograph (TEM), X-ray photoelectron spectra (XPS) and magnetization measurements. The homogeneous alpha-Fe2O3 nanoparticles with shuttle-like shape have an average length of 120 nm and a mean diameter of about 50 urn in the middle part (an average aspect ratio of about 2.5) whereas spherical alpha-Fe2O3 nanoparticles have a mean particle diameter of about 35nm. Magnetic hysteresis measurements reveal that shuttle-like alpha-Fe2O3 nanoparticles display normal ferromagnetic behaviors while spherical alpha-Fe2O3 nanoparticles exhibit weak ferromagnetic behaviors at room temperature. The two types of alpha-Fe2O3 exhibit hysteretic features with the remanence and coercivity of 0.156 emu/g and 6640e, 0.048 emu/g and 110Oe, respectively. The higher remanent magnetization and coercivity of shuttle-like alpha-Fe2O3 nanoparticles may be associated with the aspect ratio of alpha-Fe2O3 since shape anisotropy would exert a tremendous influence on their magnetic properties. (c) 2005 Elsevier Inc. All rights reserved.