Enhanced field emission of open-ended, thin-walled carbon nanotubes filled with ferromagnetic nanowires

Lv, Ruitao; Kang, Feiyu; Zhu, Di; Zhu, Yanqiu; Gui, Xuchun; Wei, Jinquan; Gu, Jing; Li, Dejie; Wang, Kunlin; Wu, Dehai

doi:10.1016/j.carbon.2009.05.027

Cited by 37 publications

(26 citation statements)

References 39 publications

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“…[168] These factors disrupt the normal dissolution of carbon into the iron phase and the precipitation at the carbon/metal interface for small-inner-diameter CNTs. [167,169] It should be noted that the inner space of CNTs can provide a confined space for advanced catalysis, nanoreactors, and energy conversion/storage. [170] However, the precise control of the outer diameter, inner diameter, and number of walls of MWCNTs is still a big challenge.…”

Section: Diameter-mediated Cnt Productionmentioning

confidence: 99%

Carbon Nanotube Mass Production: Principles and Processes

et al. 2011

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Our society requires new materials for a sustainable future, and carbon nanotubes (CNTs) are among the most important advanced materials. This Review describes the state-of-the-art of CNT synthesis, with a focus on their mass-production in industry. At the nanoscale, the production of CNTs involves the self-assembly of carbon atoms into a one-dimensional tubular structure. We describe how this synthesis can be achieved on the macroscopic scale in processes akin to the continuous tonne-scale mass production of chemical products in the modern chemical industry. Our overview includes discussions on processing methods for high-purity CNTs, and the handling of heat and mass transfer problems. Manufacturing strategies for agglomerated and aligned single-/multiwalled CNTs are used as examples of the engineering science of CNT production, which includes an understanding of their growth mechanism, agglomeration mechanism, reactor design, and process intensification. We aim to provide guidelines for the production and commercialization of CNTs. Although CNTs can now be produced on the tonne scale, knowledge of the growth mechanism at the atomic scale, the relationship between CNT structure and application, and scale-up of the production of CNTs with specific chirality are still inadequate. A multidisciplinary approach is a prerequisite for the sustainable development of the CNT industry.

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Section: Diameter-mediated Cnt Productionmentioning

confidence: 99%

Carbon Nanotube Mass Production: Principles and Processes

et al. 2011

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“…These methods suffer from some drawbacks, such as low yield of filled CNTs, deposition of metallic material on the outer surface of CNTs, and limitations imposed by capillary forces [12]. The formation and filling of CNTs can also occur simultaneously through the pyrolysis of aerosols of organometallic compounds; metallocenes can serve as a source of both the carbon shell and the magnetic core [13]. However, pyrolysis of aerosols leads to a partial and discontinuous filling of the CNTs [14].…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

Zeeshan¹,

Shou²,

Pellicer³

et al. 2011

Nanotechnology

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We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (NiMWNTs) with an average diameter of 115 nm and variable length of 400 nm -1 µm. The NiMWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H 2 /C 2 H 2 at a temperature of 700 o C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.2

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“…Both theoretical calculations [15] and experimental measurements [16] have demonstrated that the field-emission performance of CNTs depends sensitively on their tip structure, and particularly an open-ended CNT is superior to a cap-ended one. Therefore, in order to promote their practical applications in associated areas, it is crucial to develop a highly efficient and well-controlled method for the preparation of open-ended, thin-walled CNTs filled with long and continuous ferromagnetic nanowires.In this paper, we summarized our recent progress [17][18][19][20][21] in the synthesis of open-ended, thin-walled CNTs filled …”

mentioning

confidence: 99%

“…In this paper, we summarized our recent progress [17][18][19][20][21] in the synthesis of open-ended, thin-walled CNTs filled…”

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confidence: 99%

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Synthesis, field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires

Kang

et al. 2010

Sci. China Technol. Sci.

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Carbon nanotubes filled with ferromagnetic metal nanowires (M-CNTs) were synthesized by using chlorine-contained benzene (e.g. trichlorobenzene) as precursor. The wall thicknesses of M-CNTs synthesized by trichlorobenzene are much thinner than those by precursor without Cl (e.g. benzene). As-synthesized thin-walled M-CNTs exhibit remarkably enhanced field electron emission performance with a low turn-on field of 0.3 V/m and better field-emission stability. Microwave-absorption coatings were made by dispersing as-synthesized M-CNTs into epoxy resin matrix. It is found that the reflection losses in S-band (24 GHz), C-band (48 GHz) and X-band (812 GHz) are enhanced in the order of FeCoNi-CNTs < FeNi-CNTs< FeCo-CNTs. The areal density of as-prepared coatings is only 2.35 kg/m 2 when the coating thickness is 2.0 mm. This demonstrates that M-CNTs are promising to be used as lightweight and wide-band microwave absorbers. carbon nanotubes, ferromagnetic nanowires, field emission, microwave absorption Citation: Lv R T, Kang F Y, Gu J L, et al. Synthesis, field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires. Sci As a group of nanocomposites, carbon nanotubes (CNTs) filled with ferromagnetic metals (M-CNTs) can combine the electrical property of CNTs with the magnetic property of metals, and show potential applications in diverse areas, for example in high-density magnetic data storage [1], microwave absorption [2-4], human tumor therapy [5] and probes for magnetic force microscopy (MFM) [6, 7], etc. Furthermore, in this metal-filled nanostructure, CNTs can provide effective protection against the oxidation of the encapsulated metal. Up to now, several methods have been proposed to synthesize M-CNTs, such as powder pyrolysis method [6,8], template-assisted method [2,8,9], spray pyrolysis method [10,11], and so on. Despite of the great progress, these methods still have shortcomings as poor growth control [6] and complicated procedure [4,9]. Particularly, the encapsulation efficiency of metal into CNTs in previous reports seems very low, which can be seen from the following two facts: (1) the sidewalls of CNTs are very thick (8-40 nm) [6, 12, 13] and, (2) most of the metal encapsulants exist in the form of particles or short rods (length <500 nm) [10,11]. Such low filling efficiency significantly hinders their practical applications in the above-mentioned areas. Furthermore, the present CNTs are usually close-cap ended [14]. Both theoretical calculations [15] and experimental measurements [16] have demonstrated that the field-emission performance of CNTs depends sensitively on their tip structure, and particularly an open-ended CNT is superior to a cap-ended one. Therefore, in order to promote their practical applications in associated areas, it is crucial to develop a highly efficient and well-controlled method for the preparation of open-ended, thin-walled CNTs filled with long and continuous ferromagnetic nanowires.In this paper, we summarized our recent progress [17][18][19]...

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Enhanced field emission of open-ended, thin-walled carbon nanotubes filled with ferromagnetic nanowires

Cited by 37 publications

References 39 publications

Carbon Nanotube Mass Production: Principles and Processes

Carbon Nanotube Mass Production: Principles and Processes

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

Synthesis, field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires

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