ε-Phase of iron oxide out of thermally treated magnetite nanoparticles

• Published in: Journal of magnetism and magnetic materials Vol. 497; p. 165999
• Main Authors: Klekotka, Urszula, Satuła, Dariusz, Kalska-Szostko, Beata
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-03-2020; Elsevier BV
• Subjects: Argon; Heat treatment; Iron oxides; Magnetic nanoparticles; Magnetic properties; Magnetism; Magnetite; Morphology; Mössbauer spectroscopy; Nanoparticles; Phase transformation; Silicon dioxide; ε-Fe2O3; Phase transformation; ε-Fe2O3; Magnetic nanoparticles; Mössbauer spectroscopy
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.165999

•Successful fabrication of ε-Fe2O3 form magnetite is discussed.•Influence of an external condition on phase transformation is discussed.•Fe magnetic moments spatial orientation is discussed.
In this paper, ε-Fe2O3 phase was achieved by the thermal treatment of magnetite nanoparticles. Magnetite was synthesized, with or without silica shell, and treated with different annealing procedures in oxygen or argon atmospheres. Therefore, the necessary conditions for Fe3O4 transformation to ε-Fe2O3 were studied. Before and after thermal treatment, the physicochemical and magnetic properties of starting materials were investigated. The size and morphology of obtained nanostructures were characterized using Transmission Electron Microscopy. Crystalline structure and presence of γ-, α-, ε-Fe2O3 phases were examined by X-ray diffraction. Magnetic properties were studied by the Mössbauer effect with and without the presence of an external magnetic field. Obtained results show that ε-Fe2O3 phase can be achieved from magnetite nanoparticles coated with silica shell in oxygen rich environment only.