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dc.contributor.authorBoi, Filippo
dc.date.accessioned2015-09-16T11:56:05Z
dc.date.available2015-09-16T11:56:05Z
dc.date.issued2013
dc.identifier.citationBoi, F. 2013. Ferromagnetically filled carbon nanotubes: Radial structures and tuning of magnetic properties through new synthesis methods. Queen Mary University of Londonen_US
dc.identifier.urihttp://qmro.qmul.ac.uk/xmlui/handle/123456789/8734
dc.descriptionPhDen_US
dc.description.abstractMultiwall carbon nanotubes filled with continuous single-crystals of the ferromagnetic phase -Fe were produced with two new synthesis methods: the boundary layer chemical vapour synthesis and the perturbed vapour chemical vapour deposition. In the first method, the nanotubes nucleate and grow radially from a central agglomeration of homogeneously nucleated spherical particles in a randomly fluctuating vapour created in the viscous boundary layer between a rough surface and a laminar pyrolyzed-ferrocene/Ar vapour flow. In the second method, the nanotubes nucleate and form in a flower-like arrangement departing from homogeneously nucleated particles. These particles are produced by the creation of a local perturbation in a vapour with a high density of Fe and C species obtained from the pyrolysis of ferrocene in a laminar Ar flow. Electron microscopy investigations revealed that the continuous single crystals obtained with both methods exhibit diameters much lower than the critical diameter for a single magnetic domain of -Fe (~ 66 nm). In the radial structures, the single-crystal diameter is in the range of ~ 17-37 nm, while in the flower-like structures the single crystals show mainly a diameter of ~ 30 nm and ~ 55 nm. The average single crystals length is 7-8 m in the case of the radial structures and 19-21 m in the case of the flower-like structures. DC magnetization measurements at 5 K show different magnetic behaviours. The flower-like structures present a very high saturation magnetization of 189.5 emu/g and a high coercivity of 580 Oe. The radial structures exhibit an exchange-coupled ferromagnetic/antiferromagnetic system despite only 2% of -Fe is present inside the nanotubes. The radial structures obtained at flow-rates of 3.5 ccm and 20 ccm, show saturation-magnetizations of 31emu/g and 13 emu/g, and coercivities of 790 Oe and 843 Oe respectively.en_US
dc.description.sponsorshipSouth-East Physics Networken_US
dc.publisherQueen Mary University of Londonen_US
dc.subjectPhysicsen_US
dc.subjectCarbon nanotubesen_US
dc.titleFerromagnetically filled carbon nanotubes: Radial structures and tuning of magnetic properties through new synthesis methods.en_US
dc.rights.holderThe copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author


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