Preparation and magnetic study of the CoFe2O4-CoFe2 nanocomposite powders

Araújo, José Humberto de; Machado, Fernando Luis de Araujo; Cabral, Francisco de Assis Olímpio; Soares, João Maria; Rodrigues, Alexandre Ricalde; Araujo, Armando

Preparation and magnetic study of the CoFe2O4-CoFe2 nanocomposite powders

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dc.contributor.author	Araújo, José Humberto de
dc.contributor.author	Machado, Fernando Luis de Araujo
dc.contributor.author	Cabral, Francisco de Assis Olímpio
dc.contributor.author	Soares, João Maria
dc.contributor.author	Rodrigues, Alexandre Ricalde
dc.contributor.author	Araujo, Armando
dc.date.accessioned	2020-06-09T18:55:18Z
dc.date.available	2020-06-09T18:55:18Z
dc.date.issued	2008-12-16
dc.description.resumo	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	pt_BR
dc.identifier.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: https://ieeexplore.ieee.org/document/4717406 Acesso em: 09 jun 2020. http://10.1109/TMAG.2008.2001545.	pt_BR
dc.identifier.doi	10.1109/TMAG.2008.2001545
dc.identifier.issn	0018-9464
dc.identifier.uri	https://repositorio.ufrn.br/jspui/handle/123456789/29204
dc.language	en	pt_BR
dc.publisher	Institute of Electrical and Electronics Engineers	pt_BR
dc.rights	Attribution 3.0 Brazil	*
dc.rights.uri	http://creativecommons.org/licenses/by/3.0/br/	*
dc.subject	Cobalt ferrites	pt_BR
dc.subject	Exchange coupling	pt_BR
dc.subject	Nanocomposite	pt_BR
dc.subject	Material	pt_BR
dc.title	Preparation and magnetic study of the CoFe2O4-CoFe2 nanocomposite powders	pt_BR
dc.type	article	pt_BR