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

Using urea as a precipitation agent, star-like arrayed hematite (alpha-Fe2O3) particles were prepared by a facile precipitation-oxidation reaction in an aqueous solution containing ceyltrimethylammonium bromide at 80 degrees 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 alpha-Fe2O3 particles is proposed to be oriented attachment combining epitaxial overgrowth. The star-like arrayed alpha-Fe2O3 particles show a weak ferromagnetic behavior with a remanent magnetization of 5.69 x 10(-1) emu g(-1) and a coercivity of 156.08 Oe at room temperature. (C) 2009 Elsevier B.V. All rights reserved.