Naslov
Synthesis and Magnetic Properties of Hematite Particles in a “Nanomedusa” Morphology

Autori
Lee, Jin Bae ; Kim, Hae Jin ; Lužnik, Janez ; Jelen, Andreja ; Pajić, Damir ; Wencka, Magdalena ; Jagličić, Zvonko ; Meden, Anton ; Dolinšek, Janez

Izvornik
Journal of nanomaterials (1687-4110) 2014 (2014); 902968-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
hematite; nanoparticles; morphology; magnetism

Sažetak
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 930 K that matches reasonably the Néel temperature of bulk hematite. However, unlike bulk hematite that undergoes Morin 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 2 K. 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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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