Synthesis and magnetic properties of nanostructured maghemite

Nanocrystalline maghemite, gamma-Fe2O3, can be synthesized in a microwave plasma using FeCl3 or Fe-3(CO)(12) as the precursor. Electron microscopy revealed partide sizes in the range of 5 to 10 nm. In general, this material is superparamagnetic. The magnetic properties are strongly dependent on the precursor. In both cases the production process leads to a highly disordered material with the consequence of a low magnetization. The assumption of a disordered structure is also supported by electron energy loss (EEL) and Mossbauer spectroscopy. The structure of this material shows a nearly identical number of cations on tetrahedral and octahedral lattice sites.