Low-Temperature Synthesis of Maghemite Nanoparticles

Recently, the preparation of magnetic iron oxide nanoparticles has been thoroughly studied due to their unique electric and magnetic properties. Magnetic nanoparticles find uses in a wide range of applications, from data storage and sensors to medical imaging and cancer treatment. Herein, we report a fast and economic chemical procedure for the growth of monodispersed maghemite nanoparticles (NPs) from iron pentacarbonyl Fe (CO)5. The reaction takes place in a closed vessel where the oxidation strength of dimethylsulfoxide (DMSO) is limited by the reductive strength of liberated carbon monoxide from the initial complex. DMSO strips metallic Fe from the intermediate organometallic precursors (e.g. Fe2(CO)9, Fe3(CO)12), which form at temperatures above 100 °C, while at the same time oxidizes it in a controlled manner to the desired magnetic phase at temperatures as low as 130 OC, without the need for the classical refluxing step. Oleic acid is also used as a surfactant, thus maintaining a narrow size distribution of NPs. Another advantage of the synthetic route is the short reaction time (30 min).