Microwave-assisted hydrothermal synthesis and magnetic properties of nanostructured cobalt ferrite

Martinelli, Antonio Eduardo; Gurgel, Ana Lúcia; Conceição, Ozivam Lopes de Aquino; Xavier Jr, Milton Moraes; Torres, Marco Antonio Morales; Melo, Dulce Maria de Araújo

Microwave-assisted hydrothermal synthesis and magnetic properties of nanostructured cobalt ferrite

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dc.contributor.author	Martinelli, Antonio Eduardo
dc.contributor.author	Gurgel, Ana Lúcia
dc.contributor.author	Conceição, Ozivam Lopes de Aquino
dc.contributor.author	Xavier Jr, Milton Moraes
dc.contributor.author	Torres, Marco Antonio Morales
dc.contributor.author	Melo, Dulce Maria de Araújo
dc.date.accessioned	2021-02-22T13:36:08Z
dc.date.available	2021-02-22T13:36:08Z
dc.date.issued	2019-08
dc.description.resumo	Cobalt ferrite is an important magnetic material due to its high saturation magnetization and high energy product BH. CoFe2O4 nanoparticles can be synthesized by a variety of methods that often demand long synthesis times. Using the microwave-assisted hydrothermal method, single-phase CoFe2O4 with controlled crystallite size was rapidly obtained. The effect of a preheating step and mineralizing agent, i.e., NH4OH and KOH, was investigated. Exposure to microwave radiation ranged from 0.5 to 2 h. The formation of CoFe2O4 was confirmed by X-ray diffraction. The average crystallite size of CoFe2O4 nanoparticles was estimated between 5.2 nm and 21.3 nm by Rietveld refinement. The crystallite size depended on the preheating step and mineralizing agent used. Transmission electron microscopy images revealed that CoFe2O4 nanoparticles were nearly spherical when prepared with NH4OH but cubic and spherical when prepared with KOH. Both, hysteresis curves and Mossbauer spectra at room temperature, € showed superparamagnetic behavior for samples with the smaller crystallite size. Samples with larger crystallites consisted of blocked particles and depicted an increase in the MR/MHmax ratio and coercive field, Hc. Distinct magnetic properties resulting from variations in the synthesis parameters yield different applications for nanostructured CoFe2O4	pt_BR
dc.identifier.citation	GURGEL, Ana Lúcia; MARTINELLI, Antonio Eduardo; CONCEIÇÃO, Ozivam Lopes de Aquino; XAVIER, Milton Moraes; TORRES, Marco Antonio Morales; MELO, Dulce Maria de Araújo. Microwave-assisted hydrothermal synthesis and magnetic properties of nanostructured cobalt ferrite. Journal Of Alloys And Compounds, [S.L.], v. 799, p. 36-42, ago. 2019. Elsevier BV. http://dx.doi.org/10.1016/j.jallcom.2019.05.309. Disponível em: https://www.sciencedirect.com/science/article/abs/pii/S0925838819319978?via%3Dihub. Acesso em: 05 jan. 2021.	pt_BR
dc.identifier.doi	10.1016/j.jallcom.2019.05.309
dc.identifier.issn	0925-8388
dc.identifier.uri	https://repositorio.ufrn.br/handle/123456789/31583
dc.language	en	pt_BR
dc.publisher	Elsevier BV	pt_BR
dc.rights	Attribution 3.0 Brazil	*
dc.rights.uri	http://creativecommons.org/licenses/by/3.0/br/	*
dc.subject	Transition metal alloys and compounds	pt_BR
dc.subject	Nanostructured materials	pt_BR
dc.subject	Chemical synthesis	pt_BR
dc.subject	Magnetic measurements	pt_BR
dc.subject	Mossbauer spectroscopy	pt_BR
dc.title	Microwave-assisted hydrothermal synthesis and magnetic properties of nanostructured cobalt ferrite	pt_BR
dc.type	article	pt_BR