Characterization of the Oxidation of Magnetite Nanoparticles during Their Synthesis by Different Structural Analysis Techniques

Abstract

Water colloidal solutions of iron oxide nanoparticles coated with tetramethylammonium hydroxide were synthesized by co-precipitation methods. Dimensional analyses were accomplished by transmission electron microscopy (TEM) and the crystalline features of nanoparticles were studied by means of X-ray diffraction (XRD). The iron oxide nanoparticle structure was characterized by the use of the attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopic techniques. For the nanoparticle samples prepared at higher temperatures during synthesis, the Raman spectra demonstrated that magnetic core of iron oxide nanoparticles is composed of a mixture of magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃) phases. We believe that the oxidation of magnetite to maghemite has been occurred during the preparation protocol of nanoparticles performed at higher temperature.

Keywords:

• Magnetic nanoparticles
• oxidation process
• Raman spectroscopy
• temperature

Acknowledgments

This research was partially supported by JINR-RO project 04-4-1121-2015/2020. We greatly thank Dr. Ana Maria Racu (Institute of Condensed Matter Physics, Technical University Braunschweig from Germany) for the collection of the Raman spectra.