Determination of the percentage of magnetite in iron oxide nanoparticles: A comparison between mössbauer spectroscopy and Raman spectroscopy

Nanomaterials and especially iron oxide nanoparticles become more common for several fields such as data storage or biomedical applications. For these biomedical applications, iron oxide nanoparticles with a superparamagnetic state are the most used as cancer treatment, contrast agent for MRI … To obtain a superparamagnetic state, the iron oxide must be less than 20 nm in size. It exists several types of iron oxide with a superparamagnetic behaviour: magnetite (Fe3O4) and maghemite (γ-Fe2O3). For the biomedical fields, the magnetic behaviour must be maximal, therefore the iron oxide synthesised in a preferential way is magnetite. A microwave process is carried out because this synthesis allows to obtain monodisperse nanoparticles with a narrow size distribution and a good crystallinity. However, the quantity of magnetite in our samples is not known exactly. The goal of this study is to determine the amount of magnetite in our samples. The most accurate technique to determine the proportion of magnetite is Mössbauer spectroscopy. A study of our samples with this technique is carried out and is compared to another technique which is Raman spectroscopy. In this work, iron oxide nanoparticles synthesised with a microwave process are characterized by Transmission Electronic Microscopy, X-Ray Diffraction, magnetic measurements, Mössbauer spectroscopy and Raman spectroscopy.