Micro- and nano-structures of iron oxide with tunable morphologies fabricated via solvothermal process
Micro- and nano-structures of iron oxide with tunable morphologies were fabricated through a solvothermal process by adjusting experimental parameters. In this route, the ethylene glycol (EG) solution of ferric chloride hexahydrate (FeCl3·6H2O), sodium bicarbonate (NaHCO3), and ethylenediamine (EDA) was heat-treated to create the micro- and nano-structures of Fe3O4, where EG acted as both solvent and reducing agent. NaHCO3 and EDA were crucial for the morphology and size of these micro- and nano-structures. Fe3O4 micro- and nano-structures revealed solid, porous and hollow morphologies by changing the reaction time, the type of solvent, and the amount of EDA and NaHCO3. Fe3O4 nanoparticles were created by controlling experimental parameters. As the reaction progressed, nanoparticles aggregated together to form solid Fe3O4 spheres, and then inner nanoparticles dissolved and recrystallized onto the outer shell of Fe3O4 spheres having been obtained through agglomerating together and then gradually developing into hollow micro- and nano-spheres due to an Ostwald ripening mechanism. Hematite (α-Fe2O3) was synthesized using ethyl alcohol instead of EG. These magnetic micro- and nano-structures revealed excellent magnetic properties.