Ammonia-mediated Method for One-step and Surfactant-free Synthesis of Magnetite Nanoparticles

Magnetite (Fe3O4) nanoparticles have been successfully prepared by a novel one-step and surfactant-free approach utilizing ferrous ion, as a single iron source. In this manner, the reaction occurs between two aqueous solutions via the spontaneous transfer of ammonia gas from one to another in room temperature. No ferric source or oxidizing specie, oxidation controlling and capping agents are needed and the method is suited for large-scale preparation. The effects of reaction conditions on the formation of Fe3O4 were investigated using powder X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) techniques. The results have demonstrated that the pure and single phase magnetite nanoparticles were synthesized at the final pH values higher than 8. Accordingly, the formation mechanism of these nanostructures is proposed. Moreover, the vibrating sample magnetometry (VSM) measurements of the as-synthesized nanoparticles show their room temperature superparamagnetic characteristic with a typical saturation magnetization of 51 emug−1.