Rapid synthesis and characterization of spinel manganese ferrite nanopowder by microwave-assisted hydrothermal method

Spinel manganese ferrite (MnFe2O4) nanopowder is widely used in many fields, such as the targeted drugs, magnetic fluid sealing technology, magnetic resonance imaging, sewage treatment and so on. The MnFe2O4 nanopowder was synthesized by a rapid microwave hydrothermal method. The phase composition, microstructure and particle size distribution of the as-synthesized nanopowder were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and laser particle size analysis, respectively. And their static magnetic properties were measured by vibrating sample magnetometry (VSM). It is found that the microwave hydrothermal reaction time, temperature and the pH of reaction system possess the great effects on the crystallinity, crystallite size and phase composition of the prepared MnFe2O4 nanopowder, and consequently its saturation magnetization (M-s). As the reaction temperature and reaction system pH increase, the average crystallite size of the samples increases gradually, their crystallinities are improved, and the Ms of the prepared nano-MnFe2O4 firstly increase, and then decrease. The MnFe2O4 powder with an average crystallite size of 17 nm and a specific saturation magnetization of 53.6 emu.g(-1) was obtained by a microwave-assisted hydrothermal method at a reaction temperature of 130 degrees C, a reaction system pH of 12 and a reaction time of 10 min. This work provides a rapid and simple approach to prepare MnFe2O4 nanopowder with a high saturation magnetization.