Synthesis of maghemite sub-microspheres by simple solvothermal reduction method

Maghemite sub-micrometer-sized spheres were successfully a prepared by a simple solvothermal reduction route at relatively low temperature. The as-obtained sample was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), X-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID) measurements. XRD and XPS analyses indicate the formation of gamma-Fe2O3 phase. TEM results reveal that the gamma-Fe2O3 particles are spherical with the diameter of 200-400 nm. Magnetic measurements show that the Curie temperature of gamma-Fe2O3 sub-microspheres is over 400 K and the sample exhibits ferromagnetic behavior at room temperature. It is found that the sub-microspheres possess high saturation magnetization of 81 emu/g at 300 K. (C) 2006 Elsevier Inc. All rights reserved.