One-step hydrothermal process to prepare highly crystalline Fe3O4 nanoparticles with improved magnetic properties

Hydrothermal process was successfully used to synthesize Fe₃O₄ powder using ferrous chloride (FeCl₂) and diamine hydrate (H₄N₂·H₂O) as starting materials by carefully controlling the reaction conditions. The as-prepared Fe₃O₄ sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were evaluated on a vibrating sample magnetometer (VSM). The nanoscale (40 nm) Fe₃O₄ powder obtained at 140 °C for 6 h possessed a saturation magnetization of 85.8 emu/g, a little lower than that of the correspondent bulk Fe₃O₄ (92 emu/g). It is suggested that the well-crystallized Fe₃O₄ grains formed under appropriate hydrothermal conditions should be responsible for the increased saturation magnetization in nanosized Fe₃O₄.