Preparation of Monodisperse ε‐Fe 2 O 3 Nanoparticles by Crystal Structural Transformation

Monodisperse iron oxide nanoparticles in the ε‐Fe 2 O 3 phase, which is the rare orthorhombic phase among the four crystal systems of Fe 2 O 3 , are prepared via crystal structural transformation induced by heat treatment of SiO 2 ‐coated monodisperse FeO nanoparticles. The mean diameter of the resu...

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Bibliographic Details
Published in:Crystal research and technology (1979) 2017-11, Vol.52 (11)
Main Authors: Nakaya, Masafumi, Nishida, Ryo, Hosoda, Natsumi, Muramatsu, Atsushi
Format: Article
Language:English
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Summary:Monodisperse iron oxide nanoparticles in the ε‐Fe 2 O 3 phase, which is the rare orthorhombic phase among the four crystal systems of Fe 2 O 3 , are prepared via crystal structural transformation induced by heat treatment of SiO 2 ‐coated monodisperse FeO nanoparticles. The mean diameter of the resulting ε‐Fe 2 O 3 nanoparticles is 41.0 ± 4.2 nm. Compared with the as‐synthesized 40.9 ± 3.8 nm‐FeO nanoparticles, which are used as the precursor, the size and size distribution of the nanoparticles remain almost unchanged after heat treatment. By optimizing the thickness of the SiO 2 shell, coalescence of the nanoparticles during heat treatment can be prevented. XRD measurements do not detect the α‐Fe 2 O 3 phase and γ‐Fe 2 O 3 phase in the obtained sample. The resulting ε‐Fe 2 O 3 nanoparticles exhibit a high coercivity of 23.4 kOe at room temperature.
ISSN:0232-1300
1521-4079
DOI:10.1002/crat.201700110