Synthesis, Characterization and Applications of Iron Oxide Nanoparticles - a Short Review

Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (alpha-Fe2O3), magnetite (Fe3O4) and maghemite (gamma-Fe2O3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.