http://www.cnr.it/ontology/cnr/individuo/prodotto/ID179367

Synthesis and magnetic characterization of Ni nanoparticles and Ni nanoparticles in multiwalled carbon nanotubes (Articolo in rivista)

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Synthesis and magnetic characterization of Ni nanoparticles and Ni nanoparticles in multiwalled carbon nanotubes (Articolo in rivista) (literal)

Anno

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Alternative label

Gozzi D. a; Latini A. a; Capannelli G. b; Canepa F. c; Napoletano M. c; Cimberle MR. d; Tropeano M. e; (2006)
Synthesis and magnetic characterization of Ni nanoparticles and Ni nanoparticles in multiwalled carbon nanotubes
in Journal of alloys and compounds; ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE (Svizzera)
(literal)

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Gozzi D. a; Latini A. a; Capannelli G. b; Canepa F. c; Napoletano M. c; Cimberle MR. d; Tropeano M. e; (literal)

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Note

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a Univ Roma La Sapienza, Dipartimento Chim, I-00185 Rome, Italy; b INSTM, Dipartimento Chim & Chim Ind, I-16146 Genoa, Italy; c INFM, LAMIA, I-16146 Genoa, Italy; d CNR, IMEM, Dipartimento Fis, I-16146 Genoa, Italy; e INFM-LAMIA, C. so Perrone, Genova, Italy (literal)

Titolo

Synthesis and magnetic characterization of Ni nanoparticles and Ni nanoparticles in multiwalled carbon nanotubes (literal)

Abstract

Nickel nanoparticles were synthesized by reduction of nickel acetylacetonate in a monosurfactant system. These nanoparticles, mostly amorphous, were used as catalyst for the growth of multiwalled carbon nanotubes by the catalytic decomposition of methane at 500 degrees C. TEM analysis reveals a wide size distribution of the diameter of the particles centred around two main values. A detailed characterization of the magnetic properties of the Ni nanoparticles and Ni nanoparticles carbon nanotubes embedded is hereby presented. Both the systems show superparamagnetic behaviour above the blocking temperature T-B. Magnetization data are well fitted by an equation formed by two weighted Langevin functions and display the correct scaling of M/M-S versus H/T for superparamagnetic nanoparticles. The hysteresis loops obtained below T-B agree with the ferromagnetism of single-domain particles, confirmed also by the expected temperature dependence of the coercive field H-C. Differences in the coercive fields at increasing and decreasing applied magnetic fields are to be ascribed to a NiO layer originating an exchange bias with inner Ni. The smallness of the coercive fields difference (around 5 Oe) confirms that the used preparation method produces a very thin NiO layer around Ni nanoparticles. (literal)

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