Controlled synthesis of ferromagnetic MnSe_x particles

The MnSe_x (x=1,2) nanoparticles were synthesized under hydrothermal condition, by reaction of the reduced selenium and Mn²⁺ ion in the presence of hydrazine and acetic acid. By precisely controlling the pH value of the solution, a series of MnSe_x particles were synthesized. The structure and morphology of as-prepared particles were examined with x-ray diffractometer (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The average sizes of as-prepared particles varied from nanoscale to microscale with pH value increase. Furthermore, the nucleation and growth mechanism associated with pH values were discussed, which can be applied to the hydrothermal synthesis of metal chalcogenide in general. Finally, the optical and magnetic properties of as-prepared particles were measured. All as-made particles exhibit a ferromagnetic behavior with low coercivity and remanence at room temperature.