Single-crystal star-like arrayed particles of hematite: Synthesis, formation mechanism and magnetic properties

Using urea as a precipitation agent, star-like arrayed hematite (α-Fe 2O 3) particles were prepared by a facile precipitation–oxidation reaction in an aqueous solution containing ceyltrimethylammonium bromide at 80 °C. The particles were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). Reaction temperature and urea amount are found to affect significantly the morphology and phase composition of the products. The formation mechanism of star-like arrayed α-Fe 2O 3 particles is proposed to be oriented attachment combining epitaxial overgrowth. The star-like arrayed α-Fe 2O 3 particles show a weak ferromagnetic behavior with a remanent magnetization of 5.69 × 10 −1 emu g −1 and a coercivity of 156.08 Oe at room temperature.