Thermal transformation of water-dispersible magnetite nanoparticles

Thermal transformation of water-dispersible magnetite (Fe3O4) nanoparticles formed by the thermal decomposition of [Fe(NH2CONH2)(6)](NO3)(3) in triethylene glycol (TEG) was studied to explore the possibilities of the synthesis of water-dispersible maghemite (gamma-Fe2O3) using X-ray diffraction, differential thermal analysis, thermogravimetric analysis, and Fourier transformed infrared spectroscopy. The structural and magnetic properties of resulting gamma-Fe2O3 nanoparticles were characterized using N-2 adsorption-desorption, transmission electron microscopy, UV-Vis absorption spectroscopy, and vibrating sample magnetic measurements. The results show that the oxidation of Fe3O4 nanoparticles at 150 A degrees C for 6 h can produce superparamagnetic gamma-Fe2O3 nanoparticles less than 10 nm in size coated with a TEG layer. The obtained gamma-Fe2O3 nanoparticles are highly dispersible in water owing to the hydrophilic properties of the TEG coating.