Monodisperse Magnetite Nanoparticles Synthesis and Their Thermal-Stability

Monodisperse magnetite (Fe₃O₄) nanoparticles (MNPs) of 25 plusmn 5 nm were prepared by modified chemical co-precipitation, and they were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with the energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), thermogravimetry analysis (TGA), X-ray photoelectron spectroscopy (XPS) and magnetic property measurement system (MPMS). The MNPs properties and structure were investigated thoroughly, particularly for their thermal-stability after different drying treatments. The results revealed that the nanoparticles after vacuum drying tended to agglomerate more easily than others when the grain average diameter was decreased because of the evaporation of the surface and inter-particles adsorptive water, but the structure and morphology were maintained better than others after ambient air drying. Among all samples, the magnetic property was maintained best at T = 70degC. The results provide some physicochemical perspective between nanoparticles´ structure and property under thermal treatments.