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

Shuttle-like α-Fe2O3 nanoparticles have been successfully synthesized via a new soft-template route using polyethylene glycol (PEG) as polymer, cetyltrimethylammonium bromide (CTAB) as surfactant and FeCl3·6H2O as iron source materials. Meanwhile, spherical α-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 α-Fe2O3 nanoparticles with shuttle-like shape have an average length of 120 nm and a mean diameter of about 50 nm in the middle part (an average aspect ratio of about 2.5) whereas spherical α-Fe2O3 nanoparticles have a mean particle diameter of about 35 nm. Magnetic hysteresis measurements reveal that shuttle-like α-Fe2O3 nanoparticles display normal ferromagnetic behaviors while spherical α-Fe2O3 nanoparticles exhibit weak ferromagnetic behaviors at room temperature. The two types of α-Fe2O3 exhibit hysteretic features with the remanence and coercivity of 0.156 emu/g and 664 Oe, 0.048 emu/g and 110 Oe, respectively. The higher remanent magnetization and coercivity of shuttle-like α-Fe2O3 nanoparticles may be associated with the aspect ratio of α-Fe2O3 since shape anisotropy would exert a tremendous influence on their magnetic properties.

Graphical abstractShuttle-like α-Fe2O3 nanoparticles have been successfully synthesized via a new soft-template route using polyethylene glycol (PEG) as polymer, cetyltrimethylammonium bromide (CTAB) as surfactant and FeCl3·6H2O as iron source materials. The morphology of β-FeOOH appears shuttle-like, while as-calcined α-Fe2O3 at 500 °C for 4 h also contains largely shuttle-like nanostructures with an average length of 120 nm and diameter of about 50 nm in the middle part. The results indicate that the existence of the polymer–surfactant can effectively affect the size and shape of α-Fe2O3 nanocrystallites with certain aspect ratio.Figure optionsDownload full-size imageDownload as PowerPoint slide