Synthesis of maghemite sub-microspheres by simple solvothermal reduction method

Maghemite sub-micrometer-sized spheres were successfully 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 γ-Fe₂O₃ phase. TEM results reveal that the γ-Fe₂O₃ particles are spherical with the diameter of 200-400 nm. Magnetic measurements show that the Curie temperature of γ-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.