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Title: Preparation and magnetic study of the CoFe2O4-CoFe2 nanocomposite powders
Authors: Araújo, José Humberto de
Machado, Fernando Luis de Araujo
Cabral, Francisco de Assis Olímpio
Soares, João Maria
Rodrigues, Alexandre Ricalde
Araujo, Armando
Keywords: Cobalt ferrites;Exchange coupling;Nanocomposite;Material
Issue Date: 16-Dec-2008
Publisher: Institute of Electrical and Electronics Engineers
Citation: CABRAL, F. A. O.; MACHADO, F. L. A.; ARAÚJO, José Humberto de; SOARES, J. M.; Ricalde, A.; ARAÚJO, A.. Preparation and magnetic study of the CoFe2O4-CoFe2 nanocomposite powders. IEEE Transactions on Magnetics, v. 44, p. 4235-4238, 2008. Disponível em: Acesso em: 09 jun 2020. http://10.1109/TMAG.2008.2001545.
Portuguese Abstract: Ferri-ferromagnetic nanocomposites CoFe 2 O 4 -CoFe 2 were prepared via reduction of the cobalt ferrite CoFe 2 O 4 into a hydrogen atmosphere and by heat treatments. This preparation method yielded powders with relative volume fraction of CoFe 2 O 4 and CoFe 2 in the range 0-0.91. The structure and the room temperature magnetization of the samples were analyzed by X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM), and by vibrating sample magnetometry, respectively. It was found that the saturation magnetization of the nanocomposite powders increases with the volume fraction of the ferromagnetic phase while their coercivity decreases. The highest value (5 kJ/m 3 ) for the maximum energy product (BH) max was obtained for the sample containing 91% in volume of CoFe 2 . This (BH) max is 19% higher than the value measured in pure CoFe 2 O 4 . The magnetic field dependence of the magnetization did also behave as the nanocomposite powders were single-phase materials. This result indicates that the hard ferrimagnet CoFe 2 O 4 and the soft ferromagnet CoFe 2 are effectively exchange coupled and that their magnetization reverses cooperatively in the range of compositions investigated
ISSN: 0018-9464
Appears in Collections:CCET - DFTE - Artigos publicados em periódicos

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