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Size and shape effect on the magnetic properties of α-Fe2O3 nanoparticles

TitoloSize and shape effect on the magnetic properties of α-Fe2O3 nanoparticles
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione1998
AutoriSuber, L., Zysler R., A. Santiago García, Fiorani D., Angiolini M., Montone Amelia, and Dormann J.L.
RivistaMaterials Science Forum
Volume269-272
Paginazione937-942
ISSN02555476
Parole chiaveAntiferromagnetism, Ferromagnetism, Grain size and shape, Iron oxides, Magnetic field effects, Magnetic properties, Magnetization, Morin transition, Nanostructured materials, Paramagnetism, Particle size analysis, Sputter deposition, Strain, Thermal effects, Zero field cooling (ZFC)
Abstract

The magnetic properties of α-Fe2O3 nanoparticles, prepared as powders by chemical route and as granular films by sputtering, have been investigated for different size (3 - 700 nm) and shape (rhombohedral, acicular and spherical). The particle size and shape effect on the Morin transition (TM = 263 K in the bulk system) has been investigated by analyzing the temperature dependence of the zero-field-cooled (ZFC) and field-cooled (FC) magnetization. For rhombohedral (30 - 350 nm) and spherical (10 - 50 nm) particles, the Morin temperature was found to decrease with decreasing particle size and increasing magnetic field. On the other hand, acicular particles (350 - 700 nm) do not show the Morin transition, unless annealed. In samples characterized by a large distribution of particle size, the ZFC and FC measurements show the superimposed effects of the superparamagnetic behaviour of very small particles and the Morin transition for the larger ones. Only the superparamagnetic component is observed in granular films consisting of very small spherical particles (3 nm), whose average blocking temperature is about 140 K.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-0030635524&partnerID=40&md5=46ae516fcecc4f45008d7741569e06d3
Citation KeySuber1998937