Synthesis and Magnetic Properties of Hematite Particles in a ‘‘Nanomedusa’’ Morphology

Lee, Jin Bae and Kim, Hae Jin and Lužnik, Janez and Jelen, Andreja and Pajić, Damir and Wencka, Magdalena and Jagličić, Zvonko and Meden, Anton and Dolinšek, Janez (2014) Synthesis and Magnetic Properties of Hematite Particles in a ‘‘Nanomedusa’’ Morphology. Journal of Nanomaterials, 2014. pp. 1-9. ISSN 1687-4110

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Abstract

We present the synthesis, characterization, and magnetic properties of hematite particles in a peculiar “nanomedusa” morphology. The particles were prepared from an iron-silica complex by a hydrothermal process in a solution consisting of ethyl acetate and ethanol. The particles’ morphology, structure, and chemical composition were investigated by transmission electron microscopy, powder X-ray diffraction, and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The “hairy” particles consist of a spherical-like core of about 100 nm diameter and fibrous exterior composed of thin “legs” of 5 nm diameter grown along one preferential direction. The particles’ cores are crystalline and undergo a magnetic phase transition to a weakly ferromagnetic state at a temperature of 930K thatmatches reasonably the N´eel temperature of bulk hematite. However, unlike bulk hematite that undergoesMorin transition to an antiferromagnetic state around room temperature and small hematite nanoparticles that are superparamagnetic, the “nanomedusa” particles remain weakly ferromagnetic down to the lowest investigated temperature of 2K. Each particle thus represents a nanodimensional “hairy” ferromagnet in a very broad temperature interval, extending much above the room temperature. Such high-temperature ferromagnetic nanoparticles are not frequently found among the nanomaterials.

Item Type: Article
Date: 2014
Subjects: NATURAL SCIENCES > Physics
Additional Information: Article ID 902968
Divisions: Faculty of Science > Department of Physics
Publisher: Hindawi Publishing Corporation
Depositing User: Damir Pajić
Date Deposited: 04 Dec 2014 15:10
Last Modified: 04 Dec 2014 15:15
URI: http://digre.pmf.unizg.hr/id/eprint/3461

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