Synthesis and Magnetic Properties of Nanostructured Maghemite

Nanocrystalline maghemite, γ–Fe₂O₃, can be synthesized in a microwave plasma using FeCl₃ or Fe₃(CO)₁₂ as the precursor. Electron microscopy revealed particle 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 Mössbauer spectroscopy. The structure of this material shows a nearly identical number of cations on tetrahedral and octahedral lattice sites.