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Sample records for carbon nanotube growth

  1. Carbon nanotube growth density control

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  2. Templated Growth of Carbon Nanotubes

    Science.gov (United States)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  3. Nanocrystalline cobalt oxides for carbon nanotube growth

    Science.gov (United States)

    Guo, Kun; Jayatissa, Ahalapitiya H.; Jayasuriya, Ambalangodage C.

    2007-09-01

    Thin Films of nanocrystalline cobalt oxide were formed by sol-gel method. Structure, optical properties and surface properties of these films were investigated by numerous characterization techniques. These films were successfully fabricated on glass substrates below 500°C. . Micropatterns of cobalt oxide thin films were also fabricated on glass and silicon substrates by employing a lift-off method. Crystal size of these nanocrystalline cobalt films could be successfully controllable by varying the amount of cobalt precursors and number of layers. These films were used as the seeding layers for carbon nanotube growth in a CVD process By changing the concentration of monomer precursors in the solgel coating solutions, different size nanoclusters hence different size carbon nanotubes could be synthesized in CVD process. This method can be used for controlled growth of carbon nanotubes for many different applications. In this paper, detail of these experimental results will be presented.

  4. Carbon nanotube growth by PECVD: a review

    Energy Technology Data Exchange (ETDEWEB)

    Meyyappan, M; Delzeit, Lance; Cassell, Alan; Hash, David [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

    2003-05-01

    Carbon nanotubes (CNTs), due to their unique electronic and extraordinary mechanical properties, have been receiving much attention for a wide variety of applications. Recently, plasma enhanced chemical vapour deposition (PECVD) has emerged as a key growth technique to produce vertically-aligned nanotubes. This paper reviews various plasma sources currently used in CNT growth, catalyst preparation and growth results. Since the technology is in its early stages, there is a general lack of understanding of growth mechanisms, the role of the plasma itself, and the identity of key species responsible for growth. This review is aimed at the low temperature plasma research community that has successfully addressed such issues, through plasma and surface diagnostics and modelling, in semiconductor processing and diamond thin film growth.

  5. Carbon nanotubes: controlled growth and application

    Directory of Open Access Journals (Sweden)

    Chang Liu

    2013-01-01

    Full Text Available Notable progress has been made on the synthesis, properties and uses of carbon nanotubes (CNTs in the past two decades. However, the controlled growth of single-wall CNTs (SWCNTs with predefined and uniform structures remains a big challenge, and making full use of CNTs in applications still requires great effort. In this article, our strategies and recent progress on the controlled synthesis of SWCNTs by chemical vapor deposition are reviewed, and the applications of CNTs in lithium-ion batteries, transparent conductive films, and as connectors of metal atomic chains are discussed. Finally, future prospects for CNTs are considered.

  6. Increased Alignment in Carbon Nanotube Growth

    Science.gov (United States)

    Delzeit, Lance D. (Inventor)

    2007-01-01

    Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

  7. Controlling growth of aligned carbon nanotubes from porous silicon templates

    Institute of Scientific and Technical Information of China (English)

    徐东升; 郭国霖; 桂琳琳; 唐有祺; 施祖进; 金朝霞; 顾振南

    2000-01-01

    Fabricating well-aligned carbon nanotubes, especially, on a silicon substrate is very important for their applications. In this paper, an aligned carbon nanotube array has been prepared by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles embedded in porous silicon (PS) templates. High-magnification transmission electron microscopy images confirm that the nanotubes are well graphitized. The PS substrates with pore sizes between 10 and 100 nm play a control role on the growth of carbon nanotubes and the diameters of the tubes increase with the enlargement of the pores of the substrates. However, such a control role cannot be found in the macro-PS substrates.

  8. Catalytic growth of carbon nanotubes with large inner diameters

    Directory of Open Access Journals (Sweden)

    WEI REN ZHONG

    2005-02-01

    Full Text Available Carbon nanotubes (2.4 g/g catalyst, with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni–Cu–Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20–60 nm, while their outer diameter is about 40–80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni–Cu–Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

  9. Collective mechanochemical growth of carbon nanotubes

    Science.gov (United States)

    Bedewy, Mostafa M. K. M. A.

    Hierarchically ordered carbon nanotubes (CNTs) are promising for integration in high-performance structural composites, electrical interconnects, thermal interfaces, and filtration membranes. These and other applications require CNTs that are monodisperse, well aligned, and densely packed. Moreover, because more than 1 billion CNTs per square centimeter grow simultaneously in a typical chemical vapor deposition (CVD) process, understanding the collective chemical and mechanical effects of growth is key to engineering the properties of CNT-based materials. This dissertation presents tailored synthesis processes, characterization techniques, and mathematical models that enable improved control of the morphology of as-grown CNT "forests.". First, a comprehensive characterization methodology, combining synchrotron X-ray scattering and attenuation with real-time height kinetics, enabled mapping the spatiotemporal evolution of CNT diameter distribution, alignment and density. By this method, the forest mass kinetics were measured and found to follow the S-shaped Gompertz curve of population growth. Dividing a forest into subpopulations revealed size-dependent activation-deactivation competition. Additionally, in situ transmission electron microscopy (TEM) showed that the kinetics of CNT nucleation are S-shaped. Based on these findings, a collective growth model is proposed, wherein randomly oriented CNTs first nucleate then self-organize and lift-off during a crowding stage, followed by a density decay stage until self-termination when the density drops below the self-supporting threshold. Next, further X-ray data analysis enabled modeling the mechanics of entangled CNTs and proved that mechanical coupling is not only responsible for the self-organization into the aligned morphology, but is also an important limiting mechanism as significant forces ensue from diameter-dependent CNT growth rates. A custom-built CVD system was used for mechanical manipulation of growing

  10. Growth of carbon nanotubes on carbon fibers without strength degradation

    Energy Technology Data Exchange (ETDEWEB)

    De Greef, Niels [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium); Magrez, Arnaud; Forro, Laszlo [Institute of Condensed Matter Physics, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Couteau, Edina; Locquet, Jean-Pierre [Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Seo, Jin Won [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium); Institute of Condensed Matter Physics, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2012-12-15

    Carbon nanotubes (CNTs) are grown on PAN-based carbon fibers by means of catalytic chemical vapor deposition technique. By using catalytic thermal decomposition of hydrocarbon, CNTs can be grown in the temperature range of 650-750 C. However, carbon fibers suffer significant damages resulting in decrease of initial tensile strength. By applying the oxidative dehydrogenation reaction of C{sub 2}H{sub 2} with CO{sub 2}, we found an alternative way to grow CNTs on carbon fibers at low temperatures, such as 500 C. Scanning electron microscope results combined with single fiber tests indicate that this low temperature growth enables homogeneous grafting of CNTs onto carbon fibers without degradation of tensile strength. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Selective growth of carbon nanotube on silicon substrates

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOT; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    The carbon nanotube (CNT) growth of iron oxide-deposited trench-patterns and the locally-ordered CNT arrays on silicon substrate were achieved by simple thermal chemical vapor deposition(STCVD) of ethanol vapor. The CNTs were uniformly synthesized with good selectivity on trench-patterned silicon substrates. This fabrication process is compatible with currently used semiconductor-processing technologies,and the carbon-nanotube fabrication process can be widely applied for the development of electronic devices using carbon-nanotube field emitters as cold cathodes and can revolutionize the area of field-emitting electronic devices. The site-selective growth of CNT from an iron oxide nanoparticle catalyst patterned were also achieved by drying-mediated self-assembly technique. The present method offers a simple and cost-effective method to grow carbon nanotubes with self-assembled patterns.

  12. Kinetics of Laser-Assisted Carbon Nanotube Growth

    CERN Document Server

    van de Burgt, Yoeri; Mandamparambil, Rajesh

    2014-01-01

    Laser-assisted chemical vapour deposition (CVD) growth is an attractive mask-less process for growing locally aligned carbon nanotubes (CNTs) in selected places on temperature sensitive substrates. The nature of the localized process results in fast carbon nanotube growth with high experimental throughput. Here, we report on detailed investigation of growth kinetics related to physical and chemical process characteristics. Specifically, the growth kinetics is investigated by monitoring the dynamical changes of reflected laser beam intensity during growth. Benefiting from the fast growth and high experimental throughput, we investigate a wide range of experimental conditions and propose several growth regimes. Rate-limiting steps are determined using rate equations linked to the proposed growth regimes, which are further characterized by Raman spectroscopy and Scanning Electron Microscopy (SEM), therefore directly linking growth regimes to the structural quality of the CNTs. Activation energies for the differe...

  13. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    Institute of Scientific and Technical Information of China (English)

    WANG ZhenXia; LI XinNian; REN CuiLan; YONG ZhenZhong; ZHU JianKang; LUO WenYun; FANG XiaoMing

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported.The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition.High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc).The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT.The ex-perimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction.There was local cross-section deformation on MWCNTs at the interface of hetero-junction.These results involve the Important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  14. Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

  15. Watching Nanotubes Grow: In situ Photography of Vertically-Aligned Carbon Nanotube Growth During CVD

    Science.gov (United States)

    Geohegan, David B.; Puretzky, Alex A.; Ivanov, Ilia N.; Jesse, Stephen; Eres, Gyula

    2004-03-01

    In situ photography of growing vertically-aligned carbon nanotube arrays has been performed using remote microscopy within a conventional CVD tube furnace reactor. Time-lapse photography permits growth kinetics measurements over long times and growth to long lengths, a technique which is complementary to recently developed in situ time resolved reflectometry (which provides similar information for the first ten microns of growth). Here we report kinetics measurements and newly-discovered phenomena during the growth longer nanotube arrays (up to 4 millimeters). Vertically-aligned arrays of multiwall carbon nanotubes were grown on silicon wafers coated with metal catalyst films using gas acetylene mixtures. For example, the measurements reveal that these nanotube arrays display a cooperative growth mode and that growth sometimes terminates and spontaneously restarts. Most importantly, the technique enables in situ adjustment of the standard processing parameters and the results of exploratory treatments intended to prolong or reinitiate growth of nanotubes to long lengths - an essential milestone for energy management and and multifunctional composite applications. This research was sponsored by DARPA and the U.S. Department of Energy under contract DE-AC05-00OR22725 with the Oak Ridge National Laboratory, managed by UT-Battelle, LLC.

  16. Towards carbon nanotube growth into superconducting microwave resonator geometries

    OpenAIRE

    Blien, S.; Götz, K. J. G.; Stiller, P. L.; Mayer, T.; Huber, T.; Vavra, O.; Hüttel, A. K.

    2016-01-01

    The in-place growth of suspended carbon nanotubes facilitates the observation of both unperturbed electronic transport spectra and high-Q vibrational modes. For complex structures integrating, e.g., superconducting rf elements on-chip, selection of a chemically and physically resistant material that survives the chemical vapor deposition (CVD) process provides a challenge. We demonstrate the implementation of molybdenum-rhenium coplanar waveguide resonators that exhibit clear resonant behavio...

  17. Stable colloidal Co-Pd nanocatalysts for carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer, A.; Golovko, V.B.; Johnson, B.F.G.; Robertson, John [Department of Chemistry, University of Cambridge (United Kingdom); Cantoro, M.; Hofmann, S.; Wirth, C.T. [Department of Engineering, University of Cambridge (United Kingdom)

    2009-12-15

    The standard preparation method for catalysts for surface-bound growth of carbon nanotubes (CNT) is to sputter or evaporate the metal catalyst (Fe, Co, and Ni) onto the surface. A lower cost method for large areas is to use liquid delivery. Colloids have the advantage of containing the catalyst in nanocluster form. Our previously developed colloidal catalysts were successful for growth but had limited shelf-life due to oxidation and coagulation. Here, we develop an air-stable colloidal catalyst with long shelf-life of many months to years. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Zinc oxide catalyzed growth of single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    We demonstrate that zinc oxide can catalyze the growth of single-walled carbon nanotubes (SWNTs) with high efficiency by a chemical vapor deposition process. The zinc oxide nanocatalysts, prepared using a diblock copolymer templating method and characterized by atomic force microscopy (AFM), were uniformly spaced over a large deposition area with an average diameter of 1.7 nm and narrow size distribution. Dense and uniform SWNTs films with high quality were obtained by using a zinc oxide catalyst, as characterized by scanning electron microscopy (SEM), Raman spectroscopy, AFM, and high-resolution transmission electron microscopy (HRTEM).

  19. Surface chemistry of metal catalyst under carbon nanotube growth conditions

    Science.gov (United States)

    Back, Tyson Cody

    The catalyst nanoparticle is critical to the yield, type, and diameter in the growth and nucleation of carbon nanotubes. The objective of this study is focused on determining what changes take place with the catalyst chemistry under growth conditions typically seen in chemical vapor deposition, CVD, experiments. It is well known that catalyst poisoning can occur and in turn effects the catalytic activity of the nanoparticle. A complete description of this mechanism is as of yet undetermined. In order to elucidate this process iron films were deposited onto Si substrates that contained a support layer of Al2O3 or SiO2. These samples were investigated with various surface chemistry techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and electron energy loss spectroscopy (EELS). In addition, structural characteristics were investigated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface techniques were used in-situ in order to observe chemistries that might not be observable outside a CVD reactor. Two sets of experiments were performed on the silica and alumina supports. The first consisted of carbon nanotube growth at near atmospheric pressure, while the second was performed under vacuum. The oxide support was shown to have an affect on the type of nanotubes grown under identical conditions. The silica support films produced more MWNT, while the alumina support films produced more SWNT. This difference was due to the amount of ripening that takes place on the oxide supports. Also in-situ XPS revealed differences in the chemistry of iron catalyst during growth and these differences were attributed to substrate interactions between alumina and iron. Finally, in-situ XPS analysis showed no evidence of carbides or oxides acting as a catalyst during the nucleation process.

  20. Electric field effect in the growth of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, E., E-mail: ericvpp@gmail.com; Briceño-Fuenmayor, H. [Instituto Venezolano de Investigaciones Científicas (IVIC), Laboratorio de Física de Fluidos y Plasma (Venezuela, Bolivarian Republic of); Arévalo, J. [Instituto Zuliano de Investigaciones Tecnológicas (INZIT), Unidad de Caracterización y Estructura de Materiales (Venezuela, Bolivarian Republic of); Atencio, R. [Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Investigación y Tecnología de Materiales (Venezuela, Bolivarian Republic of); Corredor, L. [Instituto Zuliano de Investigaciones Tecnológicas (INZIT), Unidad de Caracterización y Estructura de Materiales (Venezuela, Bolivarian Republic of)

    2015-06-15

    The growth of carbon nanotubes (CNTs) under a controlled electric field in a chemical vapor deposition system is investigated. We evaluate the influence of this external field on the morphological and structural characteristics of CNTs. Scanning electron microscopy results display a large presence of carbonaceous material in the positive plate, which appear to be a consequence of the attraction of electric forces over the electronically unbalanced cracked carbon molecules in the heating zone. We also observe a growth behavior for CNTs, in which catalyst particles are localized either at the bottom or the upper part of the nanotube, depending on the intensity and direction of the electric field. A Raman analysis from all obtained carbon materials shows the presence of two peaks, corresponding to the D ∼ 1340 cm{sup −1} and G ∼ 1590 cm{sup −1} bands attributed to multiwall CNTs. The average diameter of the CNTs is in the range between 90 and 40 nm. These results provide experimental evidence for the dependence of the catalyst and subtract interaction on the growing mechanism, in which weak chemical or electronic interactions could stimulate a top-growing as the strongest base-growing process.

  1. Effects of oxygen on multiwall carbon nanotubes growth by PECVD

    Institute of Scientific and Technical Information of China (English)

    Chun-mei ZHANG; Ya-bo FU; Qiang CHEN; Yue-fei ZHANG

    2008-01-01

    Multiwall carbon nanotubes (MWCNTs) were grown by dielectric barrier discharge (DBD)-type plasma enhanced chemical vapor deposition (PECVD) method in downstream. The temperature was 973 K and the com-positions of gases were methane, hydrogen and oxygen in the total pressure of 0.05 MPa. The effect of O2 concen-tration in the mixture on the configuration of carbon nanotubes (CNTs) was investigated in detail. Results from scanning electron microscope (SEM) and transmis-sion electron microscope (TEM) showed that CNTs grown in CH4/H2 (38.6%/61.4%, volume) mixture have many defects and contained disordered graphitic materials. With the addition of appropriate amount of O2 (~0.67%), high-purity CNTs could be obtained. However, no CNT, even no carbon matrix existed under the condition of an excessive oxygen concentration (> 1.0%, volume) in the mixture. In order to understand the role of O2 during CNTs growth, optical emission spectroscopy (OES) was in-situ employed and the results predicted that the improve-ment of CNTs quality in O2 addition was attributed to the effect of OH oxidation from the reaction of atomic oxygen with hydrogen in the plasma.

  2. Catalytic CVD Synthesis of Carbon Nanotubes: Towards High Yield and Low Temperature Growth

    Directory of Open Access Journals (Sweden)

    Marijana Mionić

    2010-11-01

    Full Text Available The catalytic chemical vapor deposition (CCVD is currently the most flexible and economically attractive method for the growth of carbon nanotubes. Although its principle is simple, the precisely controlled growth of carbon nanotubes remains very complex because many different parameters influence the growth process. In this article, we review our recent results obtained on the synthesis of carbon nanotubes via CCVD. We discuss the role of the catalyst and the catalyst support. Our recent results obtained from the water assisted growth and the equimolar C2H2-CO2 reaction are also discussed. Both procedures lead to significantly enhanced carbon nanotube growth. In particular, the latter allows growing carbon nanotubes on diverse substrate materials at low temperatures.

  3. The Infinite Possible Growth Ambients that Support Single-Wall Carbon Nanotube Forest Growth

    Science.gov (United States)

    Kimura, Hiroe; Goto, Jundai; Yasuda, Satoshi; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N.; Hata, Kenji

    2013-11-01

    We report the virtually infinite possible carbon feedstocks which support the highly efficient growth of single-wall carbon nanotubes (SWCNTs) using on the water-assisted chemical vapor deposition method. Our results demonstrate that diverse varieties of carbon feedstocks, in the form of hydrocarbons, spanning saturated rings (e.g. trans-deca-hydronaphthalene), saturated chains (e.g. propane), unsaturated rings (e.g. dicyclopentadiene), and unsaturated chains (e.g. ethylene) could be used as a carbon feedstocks with SWCNT forests with heights exceeding 100 ums. Further, we found that all the resultant SWCNTs possessed similar average diameter indicating that the diameter was mainly determined by the catalyst rather than the carbon feedstock within this synthetic system. A demonstration of the generality was the synthesis of a carbon nanotube forest from a highly unorthodox combination of gases where trans-decahydronaphthalene acted as the carbon feedstock and benzaldehyde acted as the growth enhancer.

  4. Computational studies of small carbon and iron-carbon systems relevant to carbon nanotube growth.

    Science.gov (United States)

    Duan, Haiming; Rosén, Arne; Harutyunyan, Avetik; Curtarolo, Stefano; Bolton, Kim

    2008-11-01

    Density functional theory (DFT) calculations show that dimers and longer carbon strings are more stable than individual atoms on Fe(111) surfaces. It is therefore necessary to consider the formation of these species on the metal surfaces and their effect on the mechanism of single-walled nanotube (SWNT) growth. The good agreement between the trends (energies and structures) obtained using DFT and those based on the Brenner and AIREBO models indicate that these analytic models provide adequate descriptions of the supported carbon systems needed for valid molecular dynamics simulations of SWNT growth. In contrast, the AIREBO model provides a better description of the relative energies for isolated carbon species, and this model is preferred over the Brenner potential when simulating SWNT growth in the absence of metal particles. However, the PM3 semiempirical model appears to provide an even better description for these systems and, given sufficient computer resources, direct dynamics methods based on this model may be preferred.

  5. Single-Wall Carbon Nanotube Growth from Graphite Layers-a Tight Binding Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    Yuntuan FANG; Min ZHU; Yongshun WANG

    2003-01-01

    The growth of single-wall carbon nanotube from graphite layers is studied by tight binding molecular dynamics simulation. Given temperature of 2500 K or 3500 K and an interval of 0.25 nm for the two layers of graphite, a single-wall carbon nanotube with a zigzag shell will be produced. On the other conditions the carbon nanotube cannot grow or grows with too many defects. All carbon nanotube ends have pentagons which play an important role during the tube ends closing.

  6. Direct growth of carbon nanotubes on hydroxyapatite using MPECVD

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M., E-mail: duraia_physics@yahoo.com [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farbi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, Almaty (Kazakhstan); Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States); Hannora, A. [Suez Canal University, Faculty of Petroleum and Mining Engineering (Egypt); Mansurov, Z. [Al-Farbi Kazakh National University, Almaty (Kazakhstan); Beall, Gary W. [Texas State University-San Marcos, Department of Chemistry and Biochemistry, 601 University Dr., San Marcos, TX 78666 (United States)

    2012-01-16

    Graphical abstract: Carbon nanotubes have been grown directly on hydroxyapatite by using microwave plasma-enhanced chemical vapor deposition (MPECVD). Highlights: Black-Right-Pointing-Pointer CNTs have been successfully grown directly on hydroxyapatite using MPECVD. Black-Right-Pointing-Pointer Diameter distribution of the CNTs lies in the range from 30 to 70 nm. Black-Right-Pointing-Pointer The HA surface is partially transformed to {beta}-TCP during the deposition. Black-Right-Pointing-Pointer Grown CNTs have good quality and I{sub G}/I{sub D} ratio lies between 1.243 and 1.774. - Abstract: For the first time carbon nanotubes (CNTs) have been successfully grown directly on hydroxyapatite (HA) by using microwave plasma enhanced chemical vapor deposition (MPECVD). Such integration has potential to capitalize on the merits of both HA and CNTs. This type of coating could be useful to improve the interface between bone and the implant. Scanning electron microscope SEM investigations show that; the surface of the CNTs is relatively clean and free of amorphous carbon. The CNTs diameters lie in the range 30-70 nm. In addition HA encapsulation by carbon was observed at a growth temperature 750 Degree-Sign C. Raman spectroscopy indicates that the CNTs are of high quality and the I{sub G}/I{sub D} ratio lies between 1.243 and 1.774. The changes in the X-ray diffraction (XRD) patterns give an indication that during the plasma deposition the HA-substrate surface is subjected to a temperature sufficient for partial conversion to the {beta}-tricalcium phosphate via dehydroxylation.

  7. Carbon nanotubes instruct physiological growth and functionally mature syncytia: nongenetic engineering of cardiac myocytes.

    Science.gov (United States)

    Martinelli, Valentina; Cellot, Giada; Toma, Francesca Maria; Long, Carlin S; Caldwell, John H; Zentilin, Lorena; Giacca, Mauro; Turco, Antonio; Prato, Maurizio; Ballerini, Laura; Mestroni, Luisa

    2013-07-23

    Myocardial tissue engineering currently represents one of the most realistic strategies for cardiac repair. We have recently discovered the ability of carbon nanotube scaffolds to promote cell division and maturation in cardiomyocytes. Here, we test the hypothesis that carbon nanotube scaffolds promote cardiomyocyte growth and maturation by altering the gene expression program, implementing the cell electrophysiological properties and improving networking and maturation of functional syncytia. In our study, we combine microscopy, biological and electrophysiological methodologies, and calcium imaging, to verify whether neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes acquire a physiologically more mature phenotype compared to control (gelatin). We show that the carbon nanotube substrate stimulates the induction of a gene expression profile characteristic of terminal differentiation and physiological growth, with a 2-fold increase of α-myosin heavy chain (P carbon nanotubes appear to exert a protective effect against the pathologic stimulus of phenylephrine. Finally, cardiomyocytes on carbon nanotubes demonstrate a more mature electrophysiological phenotype of syncytia and intracellular calcium signaling. Thus, carbon nanotubes interacting with cardiomyocytes have the ability to promote physiological growth and functional maturation. These properties are unique in the current vexing field of tissue engineering, and offer unprecedented perspectives in the development of innovative therapies for cardiac repair.

  8. Laser-assisted growth of carbon nanotubes - A review

    NARCIS (Netherlands)

    Burgt, Y. van de

    2014-01-01

    Laser-assisted chemical vapor deposition (LACVD) is an attractive maskless process for growing locally carbon nanotubes at selected places on substrates that may contain temperature-sensitive components. This review gives a comprehensive overview of the reported research with respect to laser assist

  9. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Science.gov (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  10. Synthesis, alignment, growth mechanism and functional properties of carbon nanotubes and their hybrid materials with inorganic and biomaterials

    OpenAIRE

    Joshi, Ravi

    2010-01-01

    The present work comprises a novel method for selective growth of carbon nanotubes, study of their growth mechanism as well as synthesis and application of their various hybrid materials. An experimental setup is established to grow carbon nanotubes using water assisted chemical vapor deposition method. Various growth parameters were scrutinized carefully and a growth mechanism is put forth for the same method. A new methodology to prepare different hybrid materials of aligned carbon nanotube...

  11. Local growth of vertical aligned carbon nanotubes by laserinduced surface modification of coated silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zimmer, K; Boehme, R; Ruthe, D; Rudolph, Th; Rauschenbach, B [Leibniz-Institut fuer Oberflaechenmodifizierung e. V. Permoserstrasse 15, D-04318 Leipzig (Germany)

    2007-04-15

    The stimulation of carbon nanotubes (CNT) growth in a thermal CVD process using an acetylene/nitrogen gas mixture by KrF-excimer laser exposure of iron nitrate coated silicon is described. At moderate laser fluences of {approx}1 J/cm{sup 2} the growth of nanotube bundles up to 100 {mu}m consisting of vertical aligned multi-walled carbon nanotubes (VA-MWCNT) is observed. AFM measurements show the formation of nanoparticles in the laser-exposed areas. At this catalytic sites the nanotubes grow and sustain one another and forming the well-defined bundles. Via the laser exposure the control of the catalytic sites formation and consequently the nanotube growth and properties can be achieved.

  12. Growth of straight carbon nanotubes by simple thermal chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOTO; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    Straight carbon nanotubes (CNTs) were achieved by simple thermal chemical vapor deposition(STCVD) catalyzed by Mo-Fe alloy catalyst on silica supporting substrate at 700 ℃. High-resolution transmission electron microscopy images show that the straight CNTs are well graphitized with no attached amorphous carbon. Mo-Fe alloy catalyst particles play a very crucial role in the growth of straight CNTs. The straight carbon nanotubes contain much less defects than the curved nanotubes and might have potential applications for nanoelectrical devices in the future. The simple synthesis of straight CNTs may have benefit for large-scale productions.

  13. Growth of single-walled gold nanotubes confined in carbon nanotubes, studied by molecular dynamics simulations

    Science.gov (United States)

    Han, Yang; Hu, Ting; Dong, Jinming

    2013-01-01

    Growth of the single-walled gold nanotube (SWGNT), confined in the single-walled carbon nanotube (SWCNT) has been studied by using the classical molecular dynamics (MD) simulations, in which two different empirical potentials (the glue and EAM potentials) are used for the interaction between gold atoms. It is found that under the glue potential, three new SWGNTs, (3, 2), (4, 2) and (6, 3) gold tubes can be formed, in addition to the previously found (3, 3), (4, 3) and (5, 3) ones, among which two achiral ones, (4, 2) and (6, 3) gold tubes are particularly interesting because they were thought to be not the tube-like structures, or to have large enough diameter, permitting an extra gold atom chain in it. However, when the EAM potential is used, only four SWGNTs, i.e., (3, 2), (4, 2), (4, 3) and (5, 3) gold tubes could be formed in our MD simulations. After comparing all the MD simulation results with those of the first principles calculations, it is found that the EAM potential is better to describe the interaction between gold atoms than the glue potential for the MD simulation on the growth of gold tubular structure in confined CNT.

  14. Decorating multiwalled carbon nanotubes with zinc oxide nano-crystallines through hydrothermal growth process

    Institute of Scientific and Technical Information of China (English)

    LI ChenSha; QIAO YingJie; LI YuMing

    2012-01-01

    Multiwalled-carbon nanotubes coated with nano-crystalline zinc oxide (ZnO) was prepared by in situ growth of nano zinc oxide on the surfaces of carbon nanotubes through hydrothermal method.X-ray diffraction,transmission electron microscopy and scanning electron microscopy analysis techniques were used to characterize the samples.It was observed that a layer of nano-crystalline ZnO with the wurtzite hexagonal crystal structure was uniformly coated on the nanotube surfaces with good adhesion,which resulted in the formation of a novel ZnO-nanotube nano composite.In this work,the carbon nanotubes decorated by metal oxide nanoparticles were synthesized by a simple chemical-solution route which is suitable for the large-scale production with low cost.

  15. Plasma stabilisation of metallic nanoparticles on silicon for the growth of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Esconjauregui, S.; Fouquet, M.; Bayer, B. C.; Gamalski, A. D.; Chen Bingan; Xie Rongsi; Hofmann, S.; Robertson, J. [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Cepek, C.; Bhardwaj, S. [Istituto Officina dei Materiali-CNR, Laboratorio TASC, s.s. 14 km 163.5, I-34149 Trieste (Italy); Ducati, C. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2012-08-01

    Ammonia (NH{sub 3}) plasma pretreatment is used to form and temporarily reduce the mobility of Ni, Co, or Fe nanoparticles on boron-doped mono- and poly-crystalline silicon. X-ray photoemission spectroscopy proves that NH{sub 3} plasma nitrides the Si supports during nanoparticle formation which prevents excessive nanoparticle sintering/diffusion into the bulk of Si during carbon nanotube growth by chemical vapour deposition. The nitridation of Si thus leads to nanotube vertical alignment and the growth of nanotube forests by root growth mechanism.

  16. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity

    OpenAIRE

    Martínez-Ballesta, Mª Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-01-01

    Background Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. Results In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWC...

  17. A vapor-liquid-solid model for chemical vapor deposition growth of carbon nanotubes.

    Science.gov (United States)

    Jiang, Kaili; Feng, Chen; Liu, Kai; Fan, Shoushan

    2007-01-01

    Although carbon nanotubes (CNTs) with a variety of morphologies have been successfully synthesized, there is no clear physical picture of the growth process. Correspondingly, the growth mechanism is still not clear up to now. Here we suggest a VLS model for the growth process of CNTs, which involves a liquid or liquid-like state catalyst. The basic idea is that, due to the high thermal conductivity and nanometer size of the catalyst and the fast diffusion of carbon atoms in it, both the temperature and the carbon atom distribution across it are uniform. The supersaturation level can be expressed as a function of the carbon concentration and temperature, which determines the nucleation dynamics and growth kinetics. Based on this model, the growth rate equation was obtained to describe the growth kinetics of carbon nanotubes, which shows good accordance with the experimental results.

  18. Controlled growth of vertically aligned carbon nanotubes on metal substrates

    Science.gov (United States)

    Gao, Zhaoli

    Carbon nanotube (CNT) is a fascinating material with extraordinary electrical thermal and mechanical properties. Growing vertically aligned CNT (VACNT) arrays on metal substrates is an important step in bringing CNT into practical applications such as thermal interface materials (TIMs) and microelectrodes. However, the growth process is challenging due to the difficulties in preventing catalyst diffusion and controlling catalyst dewetting on metal substrates with physical surface heterogeneity. In this work, the catalyst diffusion mechanism and catalyst dewetting theory were studied for the controlled growth of VACNTs on metal substrates. The diffusion time of the catalyst, the diffusion coefficients for the catalyst in the substrate materials and the number density of catalyst nanoparticles after dewetting are identified as the key parameters, based on which three strategies are developed. Firstly, a fast-heating catalyst pretreatment strategy was used, aiming at preserving the amount of catalyst prior to CNT growth by reducing the catalyst diffusion time. The catalyst lifetime is extended from half an hour to one hour on a patterned Al thin film and a VACNT height of 106 mum, about twenty fold of that reported in the literature, was attained. Secondly, a diffusion barrier layer strategy is employed for a reduction of catalyst diffusion into the substrate materials. Enhancement of VACNT growth on Cu substrates was achieved by adopting a conformal Al2O 3 diffusion barrier layer fabricated by a specially designed atomic layer deposition (ALD) system. Lastly, a novel catalyst glancing angle deposition (GLAD) strategy is performed to manipulate the morphology of a relatively thick catalyst on metal substrates with physical surface heterogeneity, aiming to obtain uniform and dense catalyst nanoparticles after dewetting in the pretreatment process for enhanced VACNT growth. We are able to control the VACNT growth conditions on metal substrates in terms of their

  19. Support effect on carbon nanotube growth by methane chemical vapor deposition on cobalt catalysts

    International Nuclear Information System (INIS)

    The influence of the support on carbon nanotube production by methane chemical vapor deposition (CVD) on cobalt catalysts was investigated. N2 physisorption, X-ray diffractometry (XRD), temperature programmed reduction (TPR) and H2 and CO chemisorption techniques were used to characterize the structure of cobalt catalysts supported on different metal oxides (Al2O3, SiO2, Nb2O5 and TiO2). Raman spectroscopy, temperature programmed oxidation (TPO) and scanning electron microscopy (SEM) were used for the characterization and quantification of produced carbon species. On carbon nanotube growth, the catalyst produced three main carbon species: amorphous carbon, single walled carbon nanotubes (SWNT) and multi walled carbon nanotubes (MWNT). The characterization techniques showed that the catalyst selectivity to each kind of nanotube depended on the cobalt particle size distribution, which was influenced by the textural properties of the support. Co/TiO2 showed the highest selectivity towards single wall nanotube formation. This high selectivity results from the narrow size distribution of cobalt particles on TiO2. (author)

  20. Phase stability of iron-carbon nanocarbides and implications for the growth of carbon nanotubes

    Science.gov (United States)

    Awasthi, Neha

    Catalyst nanoparticles play a crucial role in the synthesis of single-walled carbon nanotubes by chemical vapor deposition technique. Understanding the thermal behavior of the nano-catalysts, their interaction with Carbon and stability of nanocarbides can give better insight into the growth mechanism and control over selective, yield of nanotubes. In this work, we present results using first-principle calculations and classical molecular dynamics simulations to understand the thermodynamics of free and Al2O3 supported Fe-C nanoparticles. We observe that the substrate plays an important role during the growth reaction by increasing the melting temperatures of small and medium size Fe nanoparticles. We investigate Fe-C phase diagrams for small Fe nanoparticles (d˜2nm) and discover that as the size of the Fe nanoparticle is reduced, the eutectic point shifted significantly toward lower temperatures, as expected from the Gibbs-Thomson law, and also toward lower concentrations of C. We devise a simple model based on the Young-Laplace pressure-radius relation, to predict the behavior of the phases competing for stability in Fe-C nanoclusters at low temperature. We identify ranges of nanoparticle sizes which are compatible for steady state-, limited- and no-growth of SWCNTs corresponding to unaffected, reduced and no solubility of C in the Fe nanoparticles. We also calculate Fe-Mo-C ternary phase diagrams to investigate the behavior of bimetallic Fe:Mo catalyst nanoparticles. Our results show that addition of Mo (upto small concentrations) lowers the minimum radius when stable carbides nucleate and poison the catalyst, which enables a larger range of catalyst nanoparticles sizes to nucleate nanotubes. We also find that pure Fe has the highest surface concentration in Fe:Mo nanoparticles and is likely to be the active nucleation site for nanotubes.

  1. Nanoscale zirconia as a nonmetallic catalyst for graphitization of carbon and growth of single- and multiwall carbon nanotubes.

    Science.gov (United States)

    Steiner, Stephen A; Baumann, Theodore F; Bayer, Bernhard C; Blume, Raoul; Worsley, Marcus A; MoberlyChan, Warren J; Shaw, Elisabeth L; Schlögl, Robert; Hart, A John; Hofmann, Stephan; Wardle, Brian L

    2009-09-01

    We report that nanoparticulate zirconia (ZrO(2)) catalyzes both growth of single-wall and multiwall carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) and graphitization of solid amorphous carbon. We observe that silica-, silicon nitride-, and alumina-supported zirconia on silicon nucleates single- and multiwall carbon nanotubes upon exposure to hydrocarbons at moderate temperatures (750 degrees C). High-pressure, time-resolved X-ray photoelectron spectroscopy (XPS) of these substrates during carbon nanotube nucleation and growth shows that the zirconia catalyst neither reduces to a metal nor forms a carbide. Point-localized energy-dispersive X-ray spectroscopy (EDAX) using scanning transmission electron microscopy (STEM) confirms catalyst nanoparticles attached to CNTs are zirconia. We also observe that carbon aerogels prepared through pyrolysis of a Zr(IV)-containing resorcinol-formaldehyde polymer aerogel precursor at 800 degrees C contain fullerenic cage structures absent in undoped carbon aerogels. Zirconia nanoparticles embedded in these carbon aerogels are further observed to act as nucleation sites for multiwall carbon nanotube growth upon exposure to hydrocarbons at CVD growth temperatures. Our study unambiguously demonstrates that a nonmetallic catalyst can catalyze CNT growth by thermal CVD while remaining in an oxidized state and provides new insight into the interactions between nanoparticulate metal oxides and carbon at elevated temperatures. PMID:19663436

  2. Crystallographic growth and alignment of carbon nanotubes on few-layer graphene

    Science.gov (United States)

    Arash, Aram; Hunley, Patrick D.; Nasseri, Mohsen; Boland, Mathias J.; Sundararajan, Abhishek; Hudak, Bethany M.; Guiton, Beth S.; Strachan, Douglas R.

    2015-03-01

    Hybrid carbon nanotube and graphene structures are emerging as an exciting material system built from a common sp2 carbon backbone. Such hybrid systems have promise for use in improving the performance of energy storage and high-speed electronic applications. Towards the attainment of such hybrid materials, the catalytic growth and crystallographic alignment of these integrated structures are investigated along with the atomic-scale features of their interfaces. The catalytic activity of nanoparticles to form carbon nanotubes on the surface of few-layer graphene is tuned through precise feedstock application. Through careful materials synthesis, the interfaces of these hybrid carbon nanotube - graphene systems are investigated through ultra-high resolution electron microscopy.

  3. Hydrogen-free spray pyrolysis chemical vapor deposition method for the carbon nanotube growth: Parametric studies

    Energy Technology Data Exchange (ETDEWEB)

    Ionescu, Mihnea Ioan; Zhang Yong; Li Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Abou-Rachid, Hakima; Lussier, Louis-Simon [Defense Research and Development Canada - Valcartier, 2459 Boulevard Pie-XI Nord, Quebec, QC. G3J 1X5 (Canada)

    2011-05-15

    Spray pyrolysis chemical vapor deposition (CVD) in the absence of hydrogen at low carrier gas flow rates has been used for the growth of carbon nanotubes (CNTs). A parametric study of the carbon nanotube growth has been conducted by optimizing various parameters such as temperature, injection speed, precursor volume, and catalyst concentration. Experimental observations and characterizations reveal that the growth rate, size and quality of the carbon nanotubes are significantly dependent on the reaction parameters. Scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques were employed to characterize the morphology, structure and crystallinity of the carbon nanotubes. The synthesis process can be applied to both semiconducting silicon wafer and conducting substrates such as carbon microfibers and stainless steel plates. This approach promises great potential in building various nanodevices with different electron conducting requirements. In addition, the absence of hydrogen as a carrier gas and the relatively low synthesis temperature (typically 750 deg. C) qualify the spray pyrolysis CVD method as a safe and easy way to scale up the CNT growth, which is applicable in industrial production.

  4. Hydrogen-free spray pyrolysis chemical vapor deposition method for the carbon nanotube growth: Parametric studies

    International Nuclear Information System (INIS)

    Spray pyrolysis chemical vapor deposition (CVD) in the absence of hydrogen at low carrier gas flow rates has been used for the growth of carbon nanotubes (CNTs). A parametric study of the carbon nanotube growth has been conducted by optimizing various parameters such as temperature, injection speed, precursor volume, and catalyst concentration. Experimental observations and characterizations reveal that the growth rate, size and quality of the carbon nanotubes are significantly dependent on the reaction parameters. Scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques were employed to characterize the morphology, structure and crystallinity of the carbon nanotubes. The synthesis process can be applied to both semiconducting silicon wafer and conducting substrates such as carbon microfibers and stainless steel plates. This approach promises great potential in building various nanodevices with different electron conducting requirements. In addition, the absence of hydrogen as a carrier gas and the relatively low synthesis temperature (typically 750 deg. C) qualify the spray pyrolysis CVD method as a safe and easy way to scale up the CNT growth, which is applicable in industrial production.

  5. Acetylene-Accelerated Alcohol Catalytic CVD Growth of Vertically Aligned Single-Walled Carbon Nanotubes

    OpenAIRE

    R. Xiang; Einarsson, E.; Okawa, J.; Miyauchi, Y.; Maruyama, S.

    2008-01-01

    Addition of only 1% of acetylene into ethanol was found to enhance the growth rate of singlewalled carbon nanotubes (SWNTs) by up to ten times. Since acetylene is a byproduct of the thermal decomposition of ethanol, this suggests an alternative fast reaction pathway to the formation of SWNTs from ethanol via byproducts of decomposition. This accelerated growth, however, only occurred in the presence of ethanol, whereas pure acetylene at the same partial pressure resulted in negligible growth ...

  6. Growth of Carbon Nanotubes on Clay: Unique Nanostructured Filler for High-Performance Polymer Nanocomposites

    NARCIS (Netherlands)

    Zhang, Wei-De; Phang, In Yee; Liu, Tianxi

    2006-01-01

    High-performance composites are produced using nanostructured clay-carbon nanotube (CNT) hybrids as a reinforcing filler. The intercalation of iron particles between the clay platelets serves as the catalyst for the growth of CNTs, while the platelets are exfoliated by the CNTs, forming the unique 3

  7. Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination

    Science.gov (United States)

    Jeong, Seojeong; Lee, Jaegeun; Kim, Hwan-Chul; Hwang, Jun Yeon; Ku, Bon-Cheol; Zakharov, Dmitri N.; Maruyama, Benji; Stach, Eric A.; Kim, Seung Min

    2016-01-01

    In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests.In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05547d

  8. Carbon nanotube-based sensor and method for detection of crack growth in a structure

    Science.gov (United States)

    Smits, Jan M. (Inventor); Kite, Marlen T. (Inventor); Moore, Thomas C. (Inventor); Wincheski, Russell A. (Inventor); Ingram, JoAnne L. (Inventor); Watkins, Anthony N. (Inventor); Williams, Phillip A. (Inventor)

    2007-01-01

    A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.

  9. Growth, modification and integration of carbon nanotubes into molecular electronics

    Science.gov (United States)

    Moscatello, Jason P.

    Molecules are the smallest possible elements for electronic devices, with active elements for such devices typically a few Angstroms in footprint area. Owing to the possibility of producing ultra-high density devices, tremendous effort has been invested in producing electronic junctions by using various types of molecules. The major issues for molecular electronics include (1) developing an effective scheme to connect molecules with the present micro- and nano-technology, (2) increasing the lifetime and stabilities of the devices, and (3) increasing their performance in comparison to the state-of-the-art devices. In this work, we attempt to use carbon nanotubes (CNTs) as the interconnecting nanoelectrodes between molecules and microelectrodes. The ultimate goal is to use two individual CNTs to sandwich molecules in a cross-bar configuration while having these CNTs connected with microelectrodes such that the junction displays the electronic character of the molecule chosen. We have successfully developed an effective scheme to connect molecules with CNTs, which is scalable to arrays of molecular electronic devices. To realize this far reaching goal, the following technical topics have been investigated. (1) Synthesis of multi-walled carbon nanotubes (MWCNTs) by thermal chemical vapor deposition (T-CVD) and plasma-enhanced chemical vapor deposition (PECVD) techniques (Chapter 3). We have evaluated the potential use of tubular and bamboo-like MWCNTs grown by T-CVD and PE-CVD in terms of their structural properties. (2) Horizontal dispersion of MWCNTs with and without surfactants, and the integration of MWCNTs to microelectrodes using deposition by dielectrophoresis (DEP) (Chapter 4). We have systematically studied the use of surfactant molecules to disperse and horizontally align MWCNTs on substrates. In addition, DEP is shown to produce impurityfree placement of MWCNTs, forming connections between microelectrodes. We demonstrate the deposition density is tunable by

  10. Growth of nanotubes for electronics

    Directory of Open Access Journals (Sweden)

    John Robertson

    2007-01-01

    Full Text Available The roadmap for semiconductor devices envisages that carbon nanotubes or semiconducting nanowires could become important in about ten years. This article reviews where carbon nanotubes could contribute to microelectronics, in terms of vias, interconnects, and field-effect transistors. It focuses particularly on the requirements microelectronics places on the growth of nanotubes. That is, control over the formation of semiconducting or metallic tubes, controlling the growth location and direction, and achieving high enough nucleation densities.

  11. Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    Mérel Philippe

    2010-01-01

    Full Text Available Abstract Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO2 layer.

  12. Enhanced Growth and Redox Characteristics of Some Conducting Polymers on Carbon Nanotube Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    R.Saraswathi

    2007-01-01

    1 Results Recent studies on the electrochemistry of a number of active compounds at carbon nanotube electrodes have proved beyond doubt their excellent electrocatalytic properties.Particularly,the advancements accomplished towards the functionalization of carbon nanotubes resulting in their enhanced solubilization in aqueous solutions have helped in the preparation of stable carbon nanotube electrodes.Glassy carbon has been invariably the preferred substrate for casting carbon nanotube electrodes.Such c...

  13. Carbon nanotube composite materials

    Energy Technology Data Exchange (ETDEWEB)

    O' Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  14. From Carbon Nanotube Crystals to Carbon Nanotube Flowers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhengjun; ZHAO Ye; ZHOU Ya

    2005-01-01

    We have investigated the very initial deposition stages of chemical vapor deposition (CVD) with ferrocene (Fe(C5H5)2) and xylene (C8H10) for growing carbon nanotubes, and made clear that the mechanism for the self-organization behaviors of nanotubes at different growth stages by this approach. For instance, the organization of nanotubes into flower-like structures at prolonged deposition is developed from the crystal-like structures formed at early growth stages, both of which are closely related to and determined by the very initial deposition stages of this CVD approach. Based on this approach, ways have been established to build up different architectures of carbon nanotubes, by controlling the initial deposition stages of the CVD process, with which we have realized the selective growth of self-organized carbon nanotube structures. This study provides a new idea for growing carbon nanotube architectures by CVD.

  15. Drawing Circuits with Carbon Nanotubes: Scratch-Induced Graphoepitaxial Growth of Carbon Nanotubes on Amorphous Silicon Oxide Substrates

    Science.gov (United States)

    Choi, Won Jin; Chung, Yoon Jang; Kim, Yun Ho; Han, Jeongho; Lee, Young-Kook; Kong, Ki-jeong; Chang, Hyunju; Lee, Young Kuk; Kim, Byoung Gak; Lee, Jeong-O

    2014-01-01

    Controlling the orientations of nanomaterials on arbitrary substrates is crucial for the development of practical applications based on such materials. The aligned epitaxial growth of single-walled carbon nanotubes (SWNTs) on specific crystallographic planes in single crystalline sapphire or quartz has been demonstrated; however, these substrates are unsuitable for large scale electronic device applications and tend to be quite expensive. Here, we report a scalable method based on graphoepitaxy for the aligned growth of SWNTs on conventional SiO2/Si substrates. The “scratches” generated by polishing were found to feature altered atomic organizations that are similar to the atomic alignments found in vicinal crystalline substrates. The linear and circular scratch lines could promote the oriented growth of SWNTs through the chemical interactions between the C atoms in SWNT and the Si adatoms in the scratches. The method presented has the potential to be used to prepare complex geometrical patterns of SWNTs by ‘drawing' circuits using SWNTs without the need for state-of-the-art equipment or complicated lithographic processes. PMID:24924480

  16. Visualizing the growth dynamics of individual single-wall carbon nanotubes

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Zhang, Lili; He, Maoshuai;

    In order to meet the increasing demand of faster and more flexible electronics and optical devices and at the same time decrease the use of the critical metals, carbon based devices are in fast development. Single walled carbon nanotube (SWCNT) based electronics is a way of addressing...... around the studied sample at elevated temperature gives a unique way of monitoring gas-solid interactions such as CNT growth. Here we show the direct experimental evidence on the growth dynamics of SW-CNTs from Co/MgO catalysts using CO as carbon source inside the environmental TEM. The evolution...

  17. Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene

    Science.gov (United States)

    Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

    2005-01-01

    Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

  18. The growth of multi-walled carbon nanotubes on natural clay minerals (kaolinite, nontronite and sepiolite)

    International Nuclear Information System (INIS)

    The suitability of clay minerals - kaolinite, nontronite and sepiolite - is studied for synthesis of nanocomposites based on carbon nanotubes. Particles of iron were used as catalysts. Prior to synthesis, kaolinite and sepiolite were doped by the catalytically active metal, whereas in the case of nontronite the presence was used of this metal in the matrix of this mineral. Synthesis of CNTs was performed by hot filament chemical vapor deposition method. The produced nanocomposites were examined by transmission and scanning electron microscopies and energy dispersive X-ray spectroscopy. The experiment verified the potential of the three microcrystalline phyllosilicates for the growth of carbon nanotubes. Under the same technology conditions, the type of catalyst carrier affects the morphology and structure of the nanotube product markedly.

  19. Growth of forest of single-walled carbon nanotubes at inhomogeneous fluxes from plasma

    International Nuclear Information System (INIS)

    The growth of forest of single-walled carbon nanotubes (SWCNTs) in plasma-enhanced chemical vapor deposition (PECVD) is studied using a deposition model. The inhomogeneity in deposition of neutrals from plasma on the SWCNTs, which is typical for growth of the nano structures in PECVD, is accounted for. It is investigated how the growth rate and the residence time of carbon atoms on SWCNT surfaces depend on the SWCNT length and the decay length characterizing deposition of neutral fluxes on the SWCNTs. The obtained results can be used for optimizing the synthesis of related nano assembles in low-temperature plasma-assisted nano fabrication

  20. Carbon Nanotubes Filled with Different Ferromagnetic Alloys Affect the Growth and Development of Rice Seedlings by Changing the C:N Ratio and Plant Hormones Concentrations

    OpenAIRE

    Hao, Yi; Yu, Feifan; Lv, Ruitao; Ma, Chuanxin; Zhang, Zetian; Rui, Yukui; Liu, Liming; Cao, Weidong; Xing, Baoshan

    2016-01-01

    The aim of this study was to investigate the phytotoxicity of thin-walled carbon nanotubes (CNTs) to rice (Oryza sativa L.) seedlings. Three different CNTs, including hollow multi-walled carbon nanotubes (MWCNTs), Fe-filled carbon nanotubes (Fe-CNTs), and Fe-Co-filled carbon nanotubes (FeCo-CNTs), were evaluated. The CNTs significantly inhibited rice growth by decreasing the concentrations of endogenous plant hormones. The carbon to nitrogen ratio (C:N ratio) significantly increased in rice r...

  1. Growth dynamics of inner tubes inside cobaltocene-filled single-walled carbon nanotubes

    Science.gov (United States)

    Kharlamova, M. V.; Kramberger, Christian; Saito, Takeshi; Shiozawa, Hidetsugu; Pichler, Thomas

    2016-08-01

    We have synthesized cobaltocene-filled 1.7-nm-mean diameter single-walled carbon nanotubes (SWCNTs) and transformed them into double-walled carbon nanotubes by annealing at temperatures between 500 and 1000 °C for 2 h in vacuum. We analyze the temperature-dependent inner tube growth inside the filled SWCNTs by Raman spectroscopy. The changes in intensity of the Raman peaks of inner tubes with the diameters ranging from 0.832 to 1.321 nm with increasing annealing temperature are traced. It is revealed that the growth temperatures of larger diameter inner tubes are higher than the ones of smaller diameter tubes. A decrease in the diameter of the inner tubes by ~0.4 nm leads to a decrease in the growth temperature by ~200 °C.

  2. Role of the catalyst in the growth of single-wall carbon nanotubes.

    Science.gov (United States)

    Balbuena, Perla B; Zhao, Jin; Huang, Shiping; Wang, Yixuan; Sakulchaicharoen, Nataphan; Resasco, Daniel E

    2006-05-01

    Classical molecular dynamics simulations are carried out to analyze the physical state of the catalyst, and the growth of single-wall carbon nanotubes under typical temperature and pressure conditions of their experimental synthesis, emphasizing the role of the catalyst/substrate interactions. It is found that a strong cluster/substrate interaction increases the cluster melting point, modifying the initial stages of carbon dissolution and precipitation on the cluster surface. Experiments performed on model Co-Mo catalysts clearly illustrate the existence of an initial period where the catalyst is formed and no nanotube growth is observed. To quantify the nature of the Co-Mo2C interaction, quantum density functional theory is applied to characterize structural and energetic features of small Co clusters deposited on a (001) Mo2C surface, revealing a strong attachment of Co-clusters to the Mo2C surface, which may increase the melting point of the cluster and prevent cluster sintering.

  3. Nanocomposite Scaffold for Chondrocyte Growth and Cartilage Tissue Engineering: Effects of Carbon Nanotube Surface Functionalization

    OpenAIRE

    Chahine, Nadeen O.; Collette, Nicole M.; Thomas, Cynthia B.; Genetos, Damian C.; Loots, Gabriela G

    2014-01-01

    The goal of this study was to assess the long-term biocompatibility of single-wall carbon nanotubes (SWNTs) for tissue engineering of articular cartilage. We hypothesized that SWNT nanocomposite scaffolds in cartilage tissue engineering can provide an improved molecular-sized substrate for stimulation of chondrocyte growth, as well as structural reinforcement of the scaffold's mechanical properties. The effect of SWNT surface functionalization (-COOH or -PEG) on chondrocyte viability and bioc...

  4. Effects of Temperature and Catalyst Concentration on the Growth of Aligned Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaodong; LI Dan; WANG Ye; LIANG Ji

    2005-01-01

    The effects of preheating and pyrolysis temperatures and catalyst concentration on the synthesis of aligned carbon nanotubes (CNTs) using ferrocene as the catalyst and xylene as the carbon source in chemical vapor deposition were experimentally studied. The as-grown aligned CNTs were characterized by field emission scanning electron microscopy, transmission electronic microscopy, high-resolution transmission electronic microscopy, and Raman spectroscopy. The growth rate, the diameters, and the degree of crystal structure of the aligned CNTs were all found to depend on the preheating and pyrolysis temperatures and the catalyst concentration. The optimized conditions for the growth of aligned CNTs resulted in a rapid growth rate of 20.4 μm/min, with the CNTs having a good, uniform crystal structure, and clean surfaces with little amorphous carbon. The results also show that higher preheating temperatures and lower ferrocene concentrations favor the growth of single-walled CNTs.

  5. In-Situ Growth of Carbon Nanotubes in a Microreactor Environment

    Science.gov (United States)

    Kona, Silpa; Harnett, Cindy

    2010-03-01

    This work presents an approach to the in-situ growth of Carbon Nanotubes (CNTs) inside a micro scale environment using thermal chemical vapor deposition technique (Thermal CVD). Microreactors provide an ideal environment for exploration of extreme nanomaterial growth conditions, because they provide homogenous reactant temperature and concentrations, and the ability to work safely and economically at high temperatures and pressures over a broad range of flows. The study of Carbon Nanotube synthesis inside sub-mm channels and microfabricated reactors is of interest both fundamentally and for applications such as chromatographic channels. Carbon nanotubes (CNTs) are also excellent materials to be used as gas sensing elements as they exhibit changes in their electronic properties on being exposed to gases and are of interest in developing gas sensors operating at room temperature. Such micro scale CNT based sensing devices offer several practical advantages over the current sensors designs available, along with opening up avenues for a more efficient and better way of sensing gases.

  6. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  7. Growth of small diameter multi-walled carbon nanotubes by arc discharge process

    Science.gov (United States)

    T. Chaudhary, K.; J., Ali; P. Yupapin, P.

    2014-03-01

    Multi-walled carbon nanotubes (MWCNTs) are grown by arc discharge method in a controlled methane environment. The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr. Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.

  8. CVD-grown horizontally aligned single-walled carbon nanotubes: synthesis routes and growth mechanisms.

    Science.gov (United States)

    Ibrahim, Imad; Bachmatiuk, Alicja; Warner, Jamie H; Büchner, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H

    2012-07-01

    Single-walled carbon nanotubes (SWCNTs) have attractive electrical and physical properties, which make them very promising for use in various applications. For some applications however, in particular those involving electronics, SWCNTs need to be synthesized with a high degree of control with respect to yield, length, alignment, diameter, and chirality. With this in mind, a great deal of effort is being directed to the precision control of vertically and horizontally aligned nanotubes. In this review the focus is on the latter, horizontally aligned tubes grown by chemical vapor deposition (CVD). The reader is provided with an in-depth review of the established vapor deposition orientation techniques. Detailed discussions on the characterization routes, growth parameters, and growth mechanisms are also provided. PMID:22619167

  9. High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate.

    Science.gov (United States)

    Guzmán de Villoria, R; Figueredo, S L; Hart, A J; Steiner, S A; Slocum, A H; Wardle, B L

    2009-10-01

    Vertically aligned carbon nanotube (CNT) arrays are grown on a moving substrate, demonstrating continuous growth of nanoscale materials with long-range order. A cold-wall chamber with an oscillating moving platform is used to locally heat a silicon growth substrate coated with an Fe/Al2O3 catalyst film for CNT growth via chemical vapor deposition. The reactant gases are introduced over the substrate through a directed nozzle to attain high-yield CNT growth. Aligned multi-wall carbon nanotube arrays (or 'forests') with heights of approximately 1 mm are achieved at substrate speeds up to 2.4 mm s(-1). Arrays grown on moving substrates at different velocities are studied in order to identify potential physical limitations of repeatable and fast growth on a continuous basis. No significant differences are noted between static and moving growth as characterized by scanning electron microscopy and Raman spectroscopy, although overall growth height is marginally reduced at the highest substrate velocity. CNT arrays produced on moving substrates are also found to be comparable to those produced through well-characterized batch processes consistent with a base-growth mechanism. Growth parameters required for the moving furnace are found to differ only slightly from those used in a comparable batch process; thermal uniformity appears to be the critical parameter for achieving large-area uniform array growth. If the continuous-growth technology is combined with a reaction zone isolation scheme common in other types of processing (e.g., in the manufacture of carbon fibers), large-scale dense and aligned CNT arrays may be efficiently grown and harvested for numerous applications including providing interlayers for advanced composite reinforcement and improved electrical and thermal transport. PMID:19752503

  10. The effect of nanocomposite packaging carbon nanotube base on organoleptic and fungal growth of Mazafati brand dates

    Science.gov (United States)

    Asgari, Parinaz; Moradi, Omid; Tajeddin, Behjat

    2014-03-01

    In this work, nanocomposite low-density polyethylene films with carbon nanotube base were prepared by solution casting from boiling xylene. Fresh Mazafati dates were placed on the packages obtained from films and stored at ambient temperature. In addition, the fungal growth and sensory attributes were monitored on the 0th, 30th, 60th, and 90th days of storage. Although films containing carbon nanotube increased shelf life of Mazafati dates compared to controls, some of the characteristics of sensory were lost.

  11. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.;

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type...... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution....

  12. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small si

  13. Plumbing carbon nanotubes

    Science.gov (United States)

    Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

    2008-01-01

    Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

  14. Initial stage of growth of single-walled carbon nanotubes: modeling and simulations.

    Science.gov (United States)

    Chaudhuri, I; Yu, Ming; Jayanthi, C S; Wu, S Y

    2014-03-19

    Because there are different pathways to grow carbon nanotubes (CNTs), a common mechanism for the synthesis of CNTs does not likely exist. However, after carbon atoms are liberated from carbon-containing precursors by catalysts or from pure carbon systems, a common feature, the nucleation of CNTs by electron mediation, does appear. We studied this feature using the initial stage of growth of single wall CNTs (SWCNTs) by transition metal nano-particle catalysts as the working example. To circumvent the bottleneck due to the size and simulation time, we used a model in which the metal droplet is represented by a jellium, and the effect of collisions between the carbon atoms and atoms of the catalyst is captured by charge transfers between the jellium and the carbon. The simulations were performed using a transferable semi-empirical Hamiltonian to model the interactions between carbon atoms in jellium. We annealed different initial configurations of carbon clusters in jellium as well as in a vacuum. We found that in jellium, elongated open tubular structures, precursors to the growth of SWCNTs, are formed. Our model was also shown to be capable of mimicking the continued growth when more atoms were placed near the open end of the tubular structure.

  15. Carbon nanotubes as plant growth regulators: effects on tomato growth, reproductive system, and soil microbial community.

    Science.gov (United States)

    Khodakovskaya, Mariya V; Kim, Bong-Soo; Kim, Jong Nam; Alimohammadi, Mohammad; Dervishi, Enkeleda; Mustafa, Thikra; Cernigla, Carl E

    2013-01-14

    Multi-walled carbon nanotubes (CNTs) can affect plant phenotype and the composition of soil microbiota. Tomato plants grown in soil supplemented with CNTs produce two times more flowers and fruit compared to plants grown in control soil. The effect of carbon nanotubes on microbial community of CNT-treated soil is determined by denaturing gradient gel electrophoresis and pyrosequencing analysis. Phylogenetic analysis indicates that Proteobacteria and Bacteroidetes are the most dominant groups in the microbial community of soil. The relative abundances of Bacteroidetes and Firmicutes are found to increase, whereas Proteobacteria and Verrucomicorbia decrease with increasing concentration of CNTs. The results of comparing diversity indices and species level phylotypes (OTUs) between samples showed that there is not a significant affect on bacterial diversity.

  16. Controlling the growth of vertically aligned single walled carbon nanotubes from ethanol for electrochemical supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Azam, M.A.; Mohamed, M.A.; Shikoh, E.; Fujiwara, A.; Shimoda, T. [Japan Advanced Inst. of Science and Technology, Ishikawa (Japan)

    2010-07-01

    Single-walled carbon nanotubes (SWCNTs) have been proven suitable for use as electrodes in electrochemical capacitors (EC). In this study, alcohol catalytic chemical vapor deposition (ACCVD) was used to grow vertically-aligned SWCNTs (VASWCNTs). An aluminium oxide (Al{sub 2}O{sub 3})-supported cobalt (Co) catalyst and high purity ethanol carbon feedstock was used for the growth process. The Al layer and Co thin films were deposited using an electron beam evaporator. CNT growth was optimized using Si/SiO{sub 2} substrates. An atomic force microscope, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were used to characterize the synthesis of the catalyst nanoparticles and their subsequent growth. Raman spectrum of the samples demonstrated peaks of radial breathing mode (RBM) from 100 to 250 per cm. Results demonstrated that the CNTs were successfully grown on the conducting metal substrate using the ACCVD process. 4 refs.

  17. The synergistic effect in the Fe-Co bimetallic catalyst system for the growth of carbon nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Hardeman, D.; Esconjauregui, S., E-mail: cse28@cam.ac.uk; Cartwright, R.; D' Arsié, L.; Robertson, J. [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Bhardwaj, S.; Cepek, C. [Istituto Officina dei Materiali-CNR, Laboratorio TASC, Trieste I-34149 (Italy); Oakes, D.; Clark, J. [Johnson Matthey Technology Centre, Sonning Common RG4 9NH (United Kingdom); Ducati, C. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2015-01-28

    We report the growth of multi-walled carbon nanotube forests employing an active-active bimetallic Fe-Co catalyst. Using this catalyst system, we observe a synergistic effect by which—in comparison to pure Fe or Co—the height of the forests increases significantly. The homogeneity in the as-grown nanotubes is also improved. By both energy dispersive spectroscopy and in-situ x-ray photoelectron spectroscopy, we show that the catalyst particles consist of Fe and Co, and this dramatically increases the growth rate of the tubes. Bimetallic catalysts are thus potentially useful for synthesising nanotube forests more efficiently.

  18. In-situ localized carbon nanotube growth inside partially sealed enclosures

    NARCIS (Netherlands)

    Burgt, Y. van de; Champion, A.; Bellouard, Y.

    2013-01-01

    Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition te

  19. Growth of Aligned Carbon Nanotubes on Large Scale by Methane Decomposition with Deactivation Inhibitor

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Zhili Li; Cheng Zhang; Feng Peng; Hongjuan Wang

    2007-01-01

    The effects of additives containing iron or nickel during chemical vapor deposition (CVD) on the growth of carbon nanotubes (CNTs) by methane decomposition on Mo/MgO catalyst were investigated. Ferrocene and nickel nitrate were introduced as deactivation inhibitors by in-situ evaporation during CVD. The precisely controlled in-situ introduction of these inhibitors increased the surface renewal of catalyst, and therefore prevented the catalyst from deactivation. Using this method, aligned multi-walled CNTs with parallel mesopores can be produced on a large scale.

  20. Understanding the growth mechanism of carbon nanotubes via the ``cluster volume to surface area" model

    Science.gov (United States)

    Mandati, Sreekanth; Kunstmann, Jens; Boerrnert, Felix; Schoenfelder, Ronny; Ruemmeli, Mark; Kar, Kamal K.; Cuniberti, Gianaurelio

    2010-03-01

    The influence of mixed catalysts for the high yield production of carbon nanotubes (CNTs) has been studied systematically. Based on extensive experimental data a ``Catalyst Volume to Surface Area'' (CVSA) model was developed to understand the influence of the process parameters on the yield and CNT diameter distribution [1]. In our study, we present a refined version of the CVSA model developed by combining experiments and simulations. We discuss our current understanding of the growth mechanism and how the model might be used to increase CNT yields by using mixed catalysts.[4pt] [1] S. Tetali et al., ACS Nano (2009), DOI: 10.1021/nn9012548.

  1. Effect of Particle Density on the Aligned Growth of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Sheng-gao; WANG Jian-hua; HAN Jian-jun

    2004-01-01

    Aligned carbon nanotubes (CNTs) were prepared on Ni-coated Ni substrate by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at temperature of 550℃.The experimental results show a direct correlation between the alignment of CNTs and the density of the catalyst particles at low temperature.When the particle density is high enough,among CNTs there are strong interactions that can inhibit CNTs from growing randomly.The crowding effect among dense CNTs results in the aligned growth of CNTs at low temperature.

  2. Molecular dynamics study of the catalyst particle size dependence on carbon nanotube growth

    Science.gov (United States)

    Ding, Feng; Rosén, Arne; Bolton, Kim

    2004-08-01

    The molecular dynamics method, based on an empirical potential energy surface, was used to study the effect of catalyst particle size on the growth mechanism and structure of single-walled carbon nanotubes (SWNTs). The temperature for nanotube nucleation (800-1100 K), which occurs on the surface of the cluster, is similar to that used in catalyst chemical vapor deposition experiments, and the growth mechanism, which is described within the vapor-liquid-solid model, is the same for all cluster sizes studied here (iron clusters containing between 10 and 200 atoms were simulated). Large catalyst particles, which contain at least 20 iron atoms, nucleate SWNTs that have a far better tubular structure than SWNTs nucleated from smaller clusters. In addition, the SWNTs that grow from the larger clusters have diameters that are similar to the cluster diameter, whereas the smaller clusters, which have diameters less than 0.5 nm, nucleate nanotubes that are ≈0.6-0.7 nm in diameter. This is in agreement with the experimental observations that SWNT diameters are similar to the catalyst particle diameter, and that the narrowest free-standing SWNT is 0.6-0.7 nm.

  3. Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

    Science.gov (United States)

    Singh, Nandita; Chen, Jinhu; Koziol, Krzysztof K.; Hallam, Keith R.; Janas, Dawid; Patil, Avinash J.; Strachan, Ally; G. Hanley, Jonathan; Rahatekar, Sameer S.

    2016-04-01

    The design of biocompatible implants for neuron repair/regeneration ideally requires high cell adhesion as well as good electrical conductivity. Here, we have shown that plasma-treated chitin carbon nanotube composite scaffolds show very good neuron adhesion as well as support of synaptic function of neurons. The addition of carbon nanotubes to a chitin biopolymer improved the electrical conductivity and the assisted oxygen plasma treatment introduced more oxygen species onto the chitin nanotube scaffold surface. Neuron viability experiments showed excellent neuron attachment onto plasma-treated chitin nanotube composite scaffolds. The support of synaptic function was evident on chitin/nanotube composites, as confirmed by PSD-95 staining. The biocompatible and electrically-conducting chitin nanotube composite scaffold prepared in this study can be used for in vitro tissue engineering of neurons and, potentially, as an implantable electrode for stimulation and repair of neurons.

  4. Reliable Growth of Vertically Aligned Carbon Nanotube Arrays by Chemical Vapor Deposition and In-situ Measurement of Fundamental Growth Kinetics in Oxygen-free Conditions

    OpenAIRE

    IN, JUNG BIN

    2011-01-01

    Vertically-aligned carbon nanotube (VACNT) arrays are both an important technological system, and a fascinating system for studying basic principles of nanomaterial synthesis. However, despite continuing efforts for the past decade, important questions about this process remain largely unexplained. Recently, nanotube research investigations have been conducted, aiming at revealing the underlying growth mechanisms, rather than merely studying the feasibility on new growth methods. Nonetheless,...

  5. Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube Growth on Silicon Using Thin SiO2 Diffusion Barriers

    OpenAIRE

    Simmons, J. M.; Nichols, B. M.; Marcus, Matthew S.; Castellini, O. M.; Hamers, R. J.; Eriksson, M. A.

    2007-01-01

    The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand the range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultra-thin oxides is greatly inhibited due to the formation of a non-catalytic silicide. Using x-ray photoelectron spectroscopy, we show that silicide formation occurs on ultra-thin ox...

  6. Mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth.

    Science.gov (United States)

    Susi, Toma; Lanzani, Giorgio; Nasibulin, Albert G; Ayala, Paola; Jiang, Tao; Bligaard, Thomas; Laasonen, Kari; Kauppinen, Esko I

    2011-06-21

    We have studied the mechanism of the initial stages of nitrogen-doped single-walled carbon nanotube growth illustrated for the case of a floating catalyst chemical vapor deposition system, which uses carbon monoxide (CO) and ammonia (NH(3)) as precursors and iron as a catalyst. We performed first-principles electronic-structure calculations, fully incorporating the effects of spin polarization and magnetic moments, to investigate the bonding and chemistry of CO, NH(3), and their fragments on a model Fe(55) icosahedral cluster. A possible dissociation path for NH(3) to atomic nitrogen and hydrogen was identified, with a reaction barrier consistent with an experimentally determined value we measured by tandem infrared and mass spectrometry. Both C-C and C-N bond formation reactions were found to be barrierless and exothermic, while a parasitic reaction of HCN formation had a barrier of over 1 eV.

  7. Nearly exclusive growth of small diameter semiconducting single-wall carbon nanotubes from organic chemistry synthetic end-cap molecules.

    Science.gov (United States)

    Liu, Bilu; Liu, Jia; Li, Hai-Bei; Bhola, Radha; Jackson, Edward A; Scott, Lawrence T; Page, Alister; Irle, Stephan; Morokuma, Keiji; Zhou, Chongwu

    2015-01-14

    The inability to synthesize single-wall carbon nanotubes (SWCNTs) possessing uniform electronic properties and chirality represents the major impediment to their widespread applications. Recently, there is growing interest to explore and synthesize well-defined carbon nanostructures, including fullerenes, short nanotubes, and sidewalls of nanotubes, aiming for controlled synthesis of SWCNTs. One noticeable advantage of such processes is that no metal catalysts are used, and the produced nanotubes will be free of metal contamination. Many of these methods, however, suffer shortcomings of either low yield or poor controllability of nanotube uniformity. Here, we report a brand new approach to achieve high-efficiency metal-free growth of nearly pure SWCNT semiconductors, as supported by extensive spectroscopic characterization, electrical transport measurements, and density functional theory calculations. Our strategy combines bottom-up organic chemistry synthesis with vapor phase epitaxy elongation. We identify a strong correlation between the electronic properties of SWCNTs and their diameters in nanotube growth. This study not only provides material platforms for electronic applications of semiconducting SWCNTs but also contributes to fundamental understanding of the growth mechanism and controlled synthesis of SWCNTs. PMID:25521257

  8. Growth of Pd-Filled Carbon Nanotubes on the Tip of Scanning Probe Microscopy

    Directory of Open Access Journals (Sweden)

    Tomokazu Sakamoto

    2009-01-01

    Full Text Available We have synthesized Pd-filled carbon nanotubes (CNTs oriented perpendicular to Si substrates using a microwave plasma-enhanced chemical vapor deposition (MPECVD for the application of scanning probe microscopy (SPM tip. Prior to the CVD growth, Al thin film (10 nm was coated on the substrate as a buffer layer followed by depositing a 5∼40 nm-thick Pd film as a catalyst. The diameter and areal density of CNTs grown depend largely on the initial Pd thickness. Scanning electron microscopy (SEM and transmission electron microscopy (TEM images clearly show that Pd is successfully encapsulated into the CNTs, probably leading to higher conductivity. Using optimum growth conditions, Pd-filled CNTs are successfully grown on the apex of the conventional SPM cantilever.

  9. Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

    Directory of Open Access Journals (Sweden)

    Qian Yong

    2009-01-01

    Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

  10. Growth of Aligned Multiwall Carbon Nanotubes and the Effect of Adsorbates on the Field Emission Properties

    Science.gov (United States)

    Milne, W. I.; Teo, K. B. K.; Lansley, S. B.; Chhowalla, M.; Amaratunga, G. A. J.; Semet, V.; Binh, Vu Thien; Pirio, G.; Legagneux, P.

    2003-10-01

    In attempt to decipher the field emission characteristics of multiwall carbon nanotubes (MWCNTs), we have developed a fabrication method based on plasma enhanced chemical vapour deposition (PECVD) to provide utmost control of the nanotube structure such as their alignment, individual position, diameter, length and morphology. We investigated the field emission properties of these nanotubes to elucidate the effect of adsorbates on the nanotubes. Our results show that although the adsorbates cause an apparent lowering of the required turn on voltage/field of the nanotubes, the adsorbates undesirably cause a saturation of the current, large temporal fluctuations in the current, and also a deviation of the emission characteristics from Fowler-Nordheim like emission. The adsorbates are easily removed by extracting an emission current of 1 uA per nanotube or using a high applied electric field (˜25V/um).

  11. Growth dynamics of carbon-metal particles and nanotubes synthesized by CO2 laser vaporization

    Science.gov (United States)

    Kokai, F.; Takahashi, K.; Yudasaka, M.; Iijima, S.

    To study the growth of carbon-Co/Ni particles and single-wall carbon nanotubes (SWNTs) by 20 ms CO2 laser-pulse irradiation of a graphite-Co/Ni (1.2 at.%) target in an Ar gas atmosphere (600 Torr), we used emission imaging spectroscopy and shadowgraphy with a temporal resolution of 1.67 ms. Wavelength-selected emission images showed that C2 emission was strong in the region close to the target (within 2 cm), while for the same region the blackbody radiation from the large clusters or particles increased with increasing distance from the target. Shadowgraph images showed that the viscous flow of carbon and metal species formed a mushroom or a turbulent cloud spreading slowly into the Ar atmosphere, indicating that particles and SWNTs continued to grow as the ejected material cooled. In addition, emission imaging spectroscopy at 1200 °C showed that C2 and hot clusters and particles with higher emission intensities were distributed over much wider areas. We discuss the growth dynamics of the particles and SWNTs through the interaction of the ambient Ar with the carbon and metal species released from the target by the laser pulse.

  12. On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Handuja Sangeeta

    2010-01-01

    Full Text Available Abstract Carbon nanotubes (CNTs were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.

  13. Modeling plasma-assisted growth of graphene-carbon nanotube hybrid

    Science.gov (United States)

    Tewari, Aarti

    2016-08-01

    A theoretical model describing the growth of graphene-CNT hybrid in a plasma medium is presented. Using the model, the growth of carbon nanotube (CNT) on a catalyst particle and thereafter the growth of the graphene on the CNT is studied under the purview of plasma sheath and number density kinetics of different plasma species. It is found that the plasma parameter such as ion density; gas ratios and process parameter such as source power affect the CNT and graphene dimensions. The variation in growth rates of graphene and CNT under different plasma power, gas ratios, and ion densities is analyzed. Based on the results obtained, it can be concluded that higher hydrocarbon ion densities and gas ratios of hydrocarbon to hydrogen favor the growth of taller CNTs and graphene, respectively. In addition, the CNT tip radius reduces with hydrogen ion density and higher plasma power favors graphene with lesser thickness. The present study can help in better understanding of the graphene-CNT hybrid growth in a plasma medium.

  14. Carbon nanotube growth on a pointed bulk electrode using femtosecond laser nonlinear lithography

    Science.gov (United States)

    Nishiyama, Hiroaki; Iba, Tomohiro; Hirata, Yoshinori

    2013-11-01

    Carbon nanotube (CNT) bundles were synthesized on pointed bulk electrodes using femtosecond laser nonlinear lithography. A resist mask of 1.5 μm diameter was formed on a pointed bulk cathode by translating a laser focus three-dimensionally inside the spherical photoresist. Metal masks obtained by pattern transfers of the resists effectively suppressed CNT growth during plasma-enhanced chemical vapor deposition, resulting in synthesis of CNT bundles only at the electrode tip. Irradiation of field emission currents from the pointed cathode enables local melting and subsequent removal of anode materials. The damaged region size and the threshold voltage for this removal process were reduced by spatial limitations of emission sites using the metal mask.

  15. Enhanced cold wall CVD reactor growth of horizontally aligned single-walled carbon nanotubes

    Science.gov (United States)

    Mu, Wei; Kwak, Eun-Hye; Chen, Bingan; Huang, Shirong; Edwards, Michael; Fu, Yifeng; Jeppson, Kjell; Teo, Kenneth; Jeong, Goo-Hwan; Liu, Johan

    2016-05-01

    HASynthesis of horizontally-aligned single-walled carbon nanotubes (HA-SWCNTs) by chemical vapor deposition (CVD) directly on quartz seems very promising for the fabrication of future nanoelectronic devices. In comparison to hot-wall CVD, synthesis of HA-SWCNTs in a cold-wall CVD chamber not only means shorter heating, cooling and growth periods, but also prevents contamination of the chamber. However, since most synthesis of HA-SWCNTs is performed in hot-wall reactors, adapting this well-established process to a cold-wall chamber becomes extremely crucial. Here, in order to transfer the CVD growth technology from a hot-wall to a cold-wall chamber, a systematic investigation has been conducted to determine the influence of process parameters on the HA-SWCNT's growth. For two reasons, the cold-wall CVD chamber was upgraded with a top heater to complement the bottom substrate heater; the first reason to maintain a more uniform temperature profile during HA-SWCNTs growth, and the second reason to preheat the precursor gas flow before projecting it onto the catalyst. Our results show that the addition of a top heater had a significant effect on the synthesis. Characterization of the CNTs shows that the average density of HA-SWCNTs is around 1 - 2 tubes/ μm with high growth quality as shown by Raman analysis. [Figure not available: see fulltext.

  16. Local growth of aligned carbon nanotubes at surface sites irradiated by pulsed laser

    Science.gov (United States)

    Zimmer, K.; Böhme, R.; Rauschenbach, B.

    2008-05-01

    The utilization of the unique properties of nanostructures often requires their arrangement in mesoscopic patterns, e.g., to facilitate the connection to microelectrodes. Such arrangements can be achieved by local growth of nanostructures. The stimulation of the localized growth of carbon nanotubes (CNT) has been achieved by excimer laser irradiation of iron(III)nitride-coated silicon substrates at a wavelength of 248 nm. After the growth using a thermal CVD process, vertical aligned CNT bundles were found within the laser-irradiated areas. Pulsed UV-laser irradiation causes the transformation of the nitride film into nanoparticles at the substrate surface as AFM measurements show. Surface modification by direct writing techniques allows the growth of arbitrary shaped CNT-forest patterns. Despite the optimization of the processing parameters, an unequal growth of CNT has been observed at the regions of pulse overlap at direct writing. The dissimilar particle properties at the overlap regions are the reason for the different CNT heights. These differences in the catalytic particles properties are caused by the lower laser fluence at the mask edges and the interaction of the laser plasma plume with the pristine nitride film.

  17. Effects of carbon nanotubes incorporation on the grain growth and properties of WC/Co nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Faming; Sun Jianfei; Shen Jun [School of Materials Science and Engineering, Harbin Inst. of Tech. (China)

    2005-07-01

    Carbon nanotubes (CNTs) combining unique mechanical and physical properties could offer a kind of nanosized reinforcements for composite materials. Incorporating of CNTs to develop advance engineering composites has become an interesting concept, but the cermets based CNTs composites have been less focused. WC-Co-CNTs nanocomposites were consolidated by spark plasma sintering (SPS) to investigate the effects of CNTs incorporation on the grain growth and mechanical properties of WC-Co nanocomposites. Experimental results show that CNTs could preserve their tubular structures in high temperature SPS process, some CNTs are surviving in the WC-Co fracture surfaces featured bridging and pulling out manner. The interaction between the CNTs and the matrix has a retardation effect of grain growth of WC, but CNTs additions could be resulted in an increase of carbon content in the binder phase that causes enhanced tendency of grain growth, either of which plays the dominated role depending on the CNTs content. The WC-10Co-0.5wt% CNTs nanocomposites possess superior hardness to toughness combinations, which hardness is about 15% and fracture toughness is about 40% higher than that of the pure nano-WC-10Co cermets consolidated under the same process. (orig.)

  18. Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

    Directory of Open Access Journals (Sweden)

    Kumar Vikram

    2008-01-01

    Full Text Available AbstractCarbon nanotube (CNT films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i mirror polished, (ii catalyst patterned, (iii mechanically polished having pits of varying size and shape, and (iv electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples.

  19. Applications of Carbon Nanotubes

    Science.gov (United States)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

  20. Organic modification of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The organic modification of carbon nanotubes is a novel research field being developed recently. In this article, the history and newest progress of organic modification of carbon nanotubes are reviewed from two aspects:organic covalent modification and organic noncovalent modification of carbon nanotubes. The preparation and properties of organic modified carbon nanotubes are discussed in detail. In addition, the prospective development of organic modification of carbon nanotubes is suggested.

  1. Fe-Ti-O based catalyst for large-chiral-angle single-walled carbon nanotube growth

    DEFF Research Database (Denmark)

    He, Maoshuai; Zhang, Lili; Jiang, Hua;

    2016-01-01

    Catalyst selection is very crucial for controlled growth of single-walled carbon nanotubes (SWNTs). Here we introduce a well-designed Fe-Ti-O solid solution for SWNT growth with a high preference to large chiral angles. The Fe-Ti-O catalyst was prepared by combining Ti layer deposition onto premade...... Fe nanoparticles with subsequent high-temperature air calcination, which favours the formation of a homogeneous Fe-Ti-O solid solution. Using CO as the carbon feedstock, chemical vapour deposition growth of SWNTs at 800 °C was demonstrated on the Fe-Ti-O catalyst. Nanobeam electron diffraction...

  2. Carboxyl-modified single-walled carbon nanotubes negatively affect bacterial growth and denitrification activity

    Science.gov (United States)

    Zheng, Xiong; Su, Yinglong; Chen, Yinguang; Wan, Rui; Li, Mu; Wei, Yuanyuan; Huang, Haining

    2014-07-01

    Single-walled carbon nanotubes (SWNTs) have been used in a wide range of fields, and the surface modification via carboxyl functionalization can further improve their physicochemical properties. However, whether carboxyl-modified SWNT poses potential risks to microbial denitrification after its release into the environment remains unknown. Here we present the possible effects of carboxyl-modified SWNT on the growth and denitrification activity of Paracoccus denitrificans (a model denitrifying bacterium). It was found that carboxyl-modified SWNT were present both outside and inside the bacteria, and thus induced bacterial growth inhibition at the concentrations of 10 and 50 mg/L. After 24 h of exposure, the final nitrate concentration in the presence of 50 mg/L carboxyl-modified SWNT was 21-fold higher than that in its absence, indicating that nitrate reduction was substantially suppressed by carboxyl-modified SWNT. The transcriptional profiling revealed that carboxyl-modified SWNT led to the transcriptional activation of the genes encoding ribonucleotide reductase in response to DNA damage and also decreased the gene expressions involved in glucose metabolism and energy production, which was an important reason for bacterial growth inhibition. Moreover, carboxyl-modified SWNT caused the significant down-regulation and lower activity of nitrate reductase, which was consistent with the decreased efficiency of nitrate reduction.

  3. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  4. Carbon nanotube macroelectronics

    Science.gov (United States)

    Zhang, Jialu

    In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to

  5. Contribution of radicals and ions in catalyzed growth of single-walled carbon nanotubes from low-temperature plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Marvi, Z. [Physics Department, Faculty of Science, Sahand University of Technology, 51335-1996 Tabriz (Iran, Islamic Republic of); Plasma Sources and Applications Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 637616 Singapore (Singapore); Xu, S. [Plasma Sources and Applications Center, NIE, and Institute of Advanced Studies, Nanyang Technological University, 637616 Singapore (Singapore); Foroutan, G. [Physics Department, Faculty of Science, Sahand University of Technology, 51335-1996 Tabriz (Iran, Islamic Republic of); Ostrikov, K. [Institute for Future Environments and School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane, QLD 4000 (Australia); Plasma Nanoscience Center Australia (PNCA), Manufacturing Flagship, CSIRO, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, NSW 2522 (Australia); School of Physics and Advanced Materials, University of Technology Sydney, Sydney, NSW 2006 (Australia)

    2015-01-15

    The growth kinetics of single-walled carbon nanotubes (SWCNTs) in a low-temperature, low-pressure reactive plasma is investigated using a multiscale numerical simulation, including the plasma sheath and surface diffusion modules. The plasma-related effects on the characteristics of SWCNT growth are studied. It is found that in the presence of reactive radicals in addition to energetic ions inside the plasma sheath area, the effective carbon flux, and the growth rate of SWCNT increase. It is shown that the concentration of atomic hydrogen and hydrocarbon radicals in the plasma plays an important role in the SWCNT growth. The effect of the effective carbon flux on the SWCNT growth rate is quantified. The dependence of the growth parameters on the substrate temperature is also investigated. The effects of the plasma sheath parameters on the growth parameters are different in low- and high-substrate temperature regimes. The optimum substrate temperature and applied DC bias are estimated to maximize the growth rate of the single-walled carbon nanotubes.

  6. Thermal conductivity of vertically aligned carbon nanotube arrays: Growth conditions and tube inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Matthew L.; Pham, Quang N.; Saltonstall, Christopher B.; Norris, Pamela M. [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904-4746 (United States)

    2014-10-13

    The thermal conductivity of vertically aligned carbon nanotube arrays (VACNTAs) grown on silicon dioxide substrates via chemical vapor deposition is measured using a 3ω technique. For each sample, the VACNTA layer and substrate are pressed to a heating line at varying pressures to extract the sample's thermophysical properties. The nanotubes' structure is observed via transmission electron microscopy and Raman spectroscopy. The presence of hydrogen and water vapor in the fabrication process is tuned to observe the effect on measured thermal properties. The presence of iron catalyst particles within the individual nanotubes prevents the array from achieving the overall thermal conductivity anticipated based on reported measurements of individual nanotubes and the packing density.

  7. Conducting carbonized polyaniline nanotubes

    Science.gov (United States)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  8. Conducting carbonized polyaniline nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  9. FLUIDIZATION OF CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    Fei Wei; Cang Huang; Yao Wang

    2005-01-01

    Carbon nanotubes (CNTs) can be fluidized in the form of fluidlike agglomerates made of many three-dimensional sub-agglomerates, having a multi-stage agglomerate (MSA) structure and containing large amounts of twisting CNTs of micrometer magnitude.

  10. Carbon nanotubes: Fibrillar pharmacology

    Science.gov (United States)

    Kostarelos, Kostas

    2010-10-01

    The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

  11. Chiral-Selective Growth of Single-Walled Carbon Nanotubes on Lattice-Mismatched Epitaxial Cobalt Nanoparticles

    DEFF Research Database (Denmark)

    He, Maoshuai; Jiang, Hua; Liu, Bilu;

    2013-01-01

    on crystalline substrates via epitaxial growth techniques. Here, we have accomplished epitaxial formation of monometallic Co nanoparticles with well-defined crystal structure, and its use as a catalyst in the selective growth of SWNTs. Dynamics of Co nanoparticles formation and SWNT growth inside an atomic......Controlling chirality in growth of single-walled carbon nanotubes (SWNTs) is important for exploiting their practical applications. For long it has been conceptually conceived that the structural control of SWNTs is potentially achievable by fabricating nanoparticle catalysts with proper structures...

  12. Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl1-xFexO3 Catalysts

    Institute of Scientific and Technical Information of China (English)

    PENG Feng; WANG Hong-juan

    2005-01-01

    A series of LaAl1-xFexO3 catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity. The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts. From the TEM pictures of carbon nanotubes, it can be found that the LaAl1-xFexO3 catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.

  13. CONTROLLED GROWTH OF CARBON NANOTUBES ON CONDUCTIVE METAL SUBSTRATES FOR ENERGY STORAGE APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.; Engtrakul, C.

    2009-01-01

    The impressive mechanical and electronic properties of carbon nanotubes (CNTs) make them ideally suited for use in a variety of nanostructured devices, especially in the realm of energy production and storage. In particular, vertically-aligned CNT “forests” have been the focus of increasing investigation for use in supercapacitor electrodes and as hydrogen adsorption substrates. Vertically-aligned CNT growth was attempted on metal substrates by waterassisted chemical vapor deposition (CVD). CNT growth was catalyzed by iron-molybdenum (FeMo) nanoparticle catalysts synthesized by a colloidal method, which were then spin-coated onto Inconel® foils. The substrates were loaded into a custom-built CVD apparatus, where CNT growth was initiated by heating the substrates to 750 °C under the fl ow of He, H2, C2H4 and a controlled amount of water vapor. The resultant CNTs were characterized by a variety of methods including Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the growth parameters were varied in an attempt to optimize the purity and growth yield of the CNTs. The surface area and hydrogen adsorption characteristics of the CNTs were quantifi ed by the Brunauer- Emmett-Teller (BET) and Sieverts methods, and their capacitance was measured via cyclic voltammetry. While vertically-aligned CNT growth could not be verifi ed, TEM and SEM analysis indicated that CNT growth was still obtained, resulting in multiwalled CNTs of a wide range in diameter along with some amorphous carbon impurities. These microscopy fi ndings were reinforced by Raman spectroscopy, which resulted in a G/D ratio ranging from 1.5 to 3 across different samples, suggestive of multiwalled CNTs. Changes in gas fl ow rates and water concentration during CNT growth were not found to have a discernable effect on the purity of the CNTs. The specifi c capacitance of a CNT/FeMo/Inconel® electrode was found to be 3.2 F/g, and the BET surface area of

  14. Nanotube composite carbon fibers

    Science.gov (United States)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  15. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  16. Growth, dispersion, and electronic devices of nitrogen-doped single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Oikonomou, Antonios [School of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Susi, Toma; Kauppinen, Esko I. [Nanomaterials Group, Department of Applied Physics, Aalto University School of Science, PO Box 15100, 00076 Aalto (Finland); Vijayaraghavan, Aravind [School of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Centre for Mesoscience and Nanotechnology, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2012-12-15

    This paper describes the complete processes from growth to electronic devices of nitrogen-doped single-wall carbon nanotubes (N-SWCNTs). The N-SWCNTs were synthesized using a floating catalyst chemical vapor deposition method. The dry-deposited N-SWCNT films were dispersed in N-methylpyrolidone followed by sonication and centrifugation steps to yield a stable dispersion of N-SWCNTs in solution. The length and diameter distribution as well as concentration of N-SWCNTs in solution were measured by atomic force microscopy and optical absorption spectroscopy, respectively. The N-SWCNTs were then assembled into electronic devices using bottom-up dielectrophoresis and characterized as field-effect transistors. Finally, the potential for application of N-SWCNTs in sensors is discussed. The three stages of N-doped SWCNT processing: (a) growth and collection on filter, (b) dispersion in NMP, and (c) dielectrophoretic assembly into transistor device. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Direct-growth carbon nanotubes on 3D structural microelectrodes for electrophysiological recording.

    Science.gov (United States)

    Pan, Alice Ian; Lin, Min-Hsuan; Chung, Hui-Wen; Chen, Hsin; Yeh, Shih-Rung; Chuang, Yung-Jen; Chang, Yen-Chung; Yew, Tri-Rung

    2016-01-01

    A novel 3D carbon nanotube (CNT) microelectrode was developed through direct growth of CNTs on a gold pin-shaped 3D microelectrode at a low temperature (400 °C) for applications in neural and cardiac recording. With an electroplated Ni catalyst layer covering the entire surface of the pin-shaped structure, CNTs were synthesized on a 3D microelectrode by catalytic thermal chemical vapor deposition (CVD). According to the analyses by electrochemical impedance spectroscopy, the impedance of 3D microelectrodes after CNT growth and UV/O3 treatment decreased from 9.3 Ω mm(-2) to 1.2 Ω mm(-2) and the capacitance increased largely from 2.2 mF cm(-2) to 73.3 mF cm(-2). The existence of UVO3-treated CNT led to a large improvement of interfacial capacitance, contributing to the decrease of impedance. The electrophysiological detection capability of this 3D CNT microelectrode was demonstrated by the distinguished P waves, QRS complex and T waves in the electrocardiogram of the zebrafish heart and the action potential recorded from individual rat hippocampal neurons. The compatibility of integration with ICs, high resolution in space, electrophysiological signals, and non-invasive long-term recording suggest that the 3D CNT microelectrode exhibits promising potential for applications in electrophysiological research and clinical trials.

  18. Role of the Initial Formation of the Iron Nano-Particles in the Multi-Walled Carbon Nanotubes Growth Process

    Institute of Scientific and Technical Information of China (English)

    Leszek Stobinski; Hong-Ming Lin

    2004-01-01

    Careful preparation of the iron nano-particle catalyst for carbon nanotubes (CNTs) fabrication has crucial importance for initial growth of multi-wall carbon-nanotubes (MWCNTs). Thin iron layer was thermally deposited in a high vacuum onto the surface of the SiO2/Si wafer at about 300 K. The sample was heated up to 700℃ in a hydrogen atmosphere, and then the sample was heated once again at750℃ in ethylene atmosphere. After hydrogen treatment continuous Fe layer was changed into many well separated Fe nano-peaks. AFM, SEM and HR-TEM studies of deposited MWCNTs allow us to propose a growth mechanism for long, straight MWCNTs.

  19. Growth of Tall Vertical Carbon Nanotube Forests using Al-Fe Catalysts and Transfer to Flexible Substrates

    OpenAIRE

    Smith, Robinson; Brown, Frank; Chester, Ashley R.

    2016-01-01

    Carbon nanotubes (CNTs) have found plenty of applications in electronics, sensing, actuation, mechanical structures, etc. There is a growing demand to produce large scale arrays of CNTs that can satisfy the requirements of cost effective, quick and relatively simpler methods of growth. The other conflicting requirement is to produce very high quality of CNTs in very high densities and volumes. There has been considerable research that has gone into resolving the above mentioned issues. Here w...

  20. Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Akito Takashima

    2014-07-01

    Full Text Available The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification.

  1. Vacuum Electron-Beam Evaporation of Fe Nanocrystals on Si3N4 Buffer Layer for carbon Nanotube Growth

    Institute of Scientific and Technical Information of China (English)

    万青; 王太宏; 林成鲁

    2003-01-01

    Vacuum electron-beam evaporated iron nanocrystal is used for the growth of carbon nanotubes. Atomic force microscopy and Raman scattering studies reveal the formation of beta-iron silicide islands on bare silicon substrate after annealing at 700°C in N2 ambient. In order to eliminate the influence of iron-silicon interaction, Si3N4 buffer layer with the thickness of 80 nm is used. This technical route prevents effectively the formation of iron silicide and improves the quality of the iron nanocrystals. Using these iron nanocrystals with high density (about 7 × 1010/cm2) as catalyst, high-density multiwall carbon nanotubes are synthesized on Si3N4/Si substrate.

  2. Growth process and mechanism of a multi-walled carbon nanotube nest deposited on a silicon nanoporous pillar array

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Weifen, E-mail: gingerwfj@yahoo.com.cn [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Jian Lv; Yang Xiaohui [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Li Xinjian [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2010-03-01

    A large scale nest array of multi-walled carbon nanotubes (NACNTs) was grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition. Through observing its macro/micromorphology and structure, ascertaining the catalyst component and its locations at different growth time by hiring field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction, the growth process was deduced. Its thermal properties were also investigated by using a thermogravimetric analyzer. Our experiments demonstrated that the CNTs growth by means of root-growth mechanism at the initial growth stage, then a continuous growth process with its tip open is suggested, finally, a schematic growth model of NACNT/Si-NPA was presented.

  3. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting.

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-19

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media. PMID:27389659

  4. Novel growth method of carbon nanotubes using catalyst-support layer developed by alumina grit blasting

    Science.gov (United States)

    Watanabe, Hiromichi; Ishii, Juntaro; Ota, Keishin

    2016-08-01

    We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals, alloys, and carbon materials using chemical vapor deposition (CVD) assisted by a simple surface treatment of the materials. The main feature of this method is the application of grit blasting with fine alumina particles to the development of a catalyst-support layer required for the growth of CNTs on various conductive materials, including ultra-hard metals such as tungsten. Auger electron spectroscopy shows that grit blasting can form a non-continuous layer where alumina nanoparticles are embedded as residues in the blasting media left on the treated surfaces. This work reveals that such a non-continuous alumina layer can behave as the catalyst-support layer, which is generally prepared by sputter or a vacuum evaporation coating process that considerably restricts the practical applications of CNTs. We have attempted to grow CNTs on grit-blasted substrates of eighteen conventionally used conductive materials using CVD together with a floating iron catalyst. The proposed method was successful in growing multi-walled CNT arrays on the grit-blasted surfaces of all the examined materials, demonstrating its versatility. Furthermore, we found that the group IV metal oxide films thermally grown on the as-received substrates can support the catalytic activity of iron nanoparticles in the CVD process just as well as the alumina film developed by grit blasting. Spectral emissivity of the CNT arrays in the visible and infrared wavelength ranges has been determined to assess the applicability of the CNT arrays as a black coating media.

  5. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconduct

  6. Effects of a carbon nanotube-collagen coating on a titanium surface on osteoblast growth

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Eun, E-mail: pje312@naver.com; Park, Il-Song, E-mail: ilsong@jbnu.ac.kr; Neupane, Madhav Prasad; Bae, Tae-Sung; Lee, Min-Ho, E-mail: lmh@jbnu.ac.kr

    2014-02-15

    This study was performed to evaluate the effect of collagen-multi-walled carbon nanotubes (MWCNTs) composite coating deposited on titanium on osteoblast growth. Titanium samples coated with only collagen and MWCNTs were used as controls. Pure titanium was coated with collagen-MWCNTs composite coating with 5, 10 and 20 μg cm{sup −2} MWCNTs by dip coating method. Scanning probe microscopy, field emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy were used to ascertain the root mean squared roughness, structural and morphological features and, the interaction between the collagen and the MWCNTs, respectively. The biocompatibility of the collagen-MWCNTs composite coated Ti was assessed by MTT and ALP activity assays after culturing the cells for 2 and 5 days. The study reveals that root mean squared surface roughness of collagen-MWCNTs composite coated titanium is relatively higher than those of collagen and MWCNTs coated Ti. There is a strong interaction between the MWCNTs and the collagen, which is supported by the inferences made in FE-SEM and TEM studies and further confirmed by FT-IR spectra. Among all the specimens tested, cell proliferation is relatively higher on collagen-MWCNTs composite coated Ti specimen incorporated with 20 μg cm{sup −2} of MWCNTs (p < 0.05) after 5 days of cell culture. Cell proliferation studies confirm the existence of a strong dependence of the extent of cell proliferation on the amount of MWCNTs incorporated in the composite; the higher the amount of MWCNTs, the greater the extent of cell proliferation. The higher surface roughness of collagen-MWCNTs composite coated Ti specimens is considered responsible for the relatively higher extent of cell proliferation. The MWCNTs incorporated in the composite could have also contributed to the cell viability and growth.

  7. Localized CVD growth of oriented and individual carbon nanotubes from nanoscaled dots prepared by lithographic sequences

    OpenAIRE

    Vigolo, Bridgite; Cojocaru, Costel Sorin; Faerber, Jaques; Arabski, J.; Gangloff, Laurent; Legagneux, Pierre; Lezec, Henry; Le Normand, Francois

    2008-01-01

    International audience Using a combination of top-down lithographic techniques, isolated, individual and oriented multi-wall carbon nanotubes (MWNTs) were grown on nickel or iron nanoscaled dots. In the first step of the process, micron-sized catalytic metallic dots (either iron or nickel) were prepared using UV lithography. MWNTs were then synthesized from these catalysts using a direct current plasma-assistance and hot-filament-enhanced chemical vapor deposition (CVD) reactor. Samples we...

  8. Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 马志斌; 王传新; 满卫东

    2005-01-01

    Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 ℃. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

  9. INTERACTION-MEDIATED GROWTH OF CARBON NANOTUBES ON ACICULAR SILICA-COATED α-Fe CATALYST BY CHEMICAL VAPOR DEPOSITION

    Institute of Scientific and Technical Information of China (English)

    Qixiang Wang; Guoqing Ning; Fei Wei; Guohua Luo

    2003-01-01

    Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular α-Fe catalyst particles. The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer. This interaction-mediated growth mechanism is illustrated by studying the electronic, atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA) and Raman spectra.

  10. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.;

    2008-01-01

    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  11. Horizontal carbon nanotube alignment.

    Science.gov (United States)

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  12. Carbon Nanotube Solar Cells

    OpenAIRE

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabr...

  13. Growth of carbon nanotubes and microfibers over stainless steel mesh by cracking of methane

    OpenAIRE

    Gao, L.Z.; Kiwi-Minsker, L.; Renken, A.

    2008-01-01

    The ${La}_{2}{NiO}_{4}$ film was synthesized on the 304 stainless steel (SS) mesh. The hydrogen reduction of La2NiO4 generated homogeneous nanocatalyst particles (probably ${Ni}/{La}_2{O}_{3}$) over which methane was cracked, producing carbon notubes/microfibers and hydrogen. The carbon nanotubes/microfibers were strongly bonded to the SS mesh. It was observed that the methane conversion always reached its maximum at the cracking temperature of 750 °C regardless of its concentration varying f...

  14. Carbon : nickel nanocomposite templates - predefined stable catalysts for diameter-controlled growth of single-walled carbon nanotubes

    Science.gov (United States)

    Melkhanova, Svetlana; Haluska, Miro; Hübner, René; Kunze, Tim; Keller, Adrian; Abrasonis, Gintautas; Gemming, Sibylle; Krause, Matthias

    2016-08-01

    Carbon : nickel (C : Ni) nanocomposite templates (NCTs) were used as catalyst precursors for diameter-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD). Two NCT types of 2 nm thickness were prepared by ion beam co-sputtering without (type I) or with assisting Ar+ ion irradiation (type II). NCT type I comprised Ni-rich nanoparticles (NPs) with defined diameter in an amorphous carbon matrix, while NCT type II was a homogenous C : Ni film. Based on the Raman spectra of more than 600 individual SWCNTs, the diameter distribution obtained from both types of NCT was determined. SWCNTs with a selective, monomodal diameter distribution are obtained from NCT type I. About 50% of the SWCNTs have a diameter of (1.36 +/- 0.10) nm. In contrast to NCT type I, SWCNTs with a non-selective, relatively homogeneous diameter distribution from 0.80 to 1.40 nm covering 88% of all SWCNTs are obtained from NCT type II. From both catalyst templates predominantly separated as-grown SWCNTs are obtained. They are free of solvents or surfactants, exhibit a low degree of bundling and contain negligible amounts of MWCNTs. The study demonstrates the advantage of predefined catalysts for diameter-controlled SWCNT synthesis in comparison to in situ formed catalysts.Carbon : nickel (C : Ni) nanocomposite templates (NCTs) were used as catalyst precursors for diameter-controlled growth of single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition (CVD). Two NCT types of 2 nm thickness were prepared by ion beam co-sputtering without (type I) or with assisting Ar+ ion irradiation (type II). NCT type I comprised Ni-rich nanoparticles (NPs) with defined diameter in an amorphous carbon matrix, while NCT type II was a homogenous C : Ni film. Based on the Raman spectra of more than 600 individual SWCNTs, the diameter distribution obtained from both types of NCT was determined. SWCNTs with a selective, monomodal diameter distribution are obtained from NCT

  15. Carbon Nanotube Purification

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

    2005-01-01

    A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

  16. Growth Mechanism of a Hybrid Structure Consisting of a Graphite Layer on Top of Vertical Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Nicolo' Chiodarelli

    2012-01-01

    Full Text Available Graphene and carbon nanotubes (CNTs are both carbon-based materials with remarkable optical and electronic properties which, among others, may find applications as transparent electrodes or as interconnects in microchips, respectively. This work reports on the formation of a hybrid structure composed of a graphitic carbon layer on top of vertical CNT in a single deposition process. The mechanism of deposition is explained according to the thickness of catalyst used and the atypical growth conditions. Key factors dictating the hybrid growth are the film thickness and the time dynamic through which the catalyst film dewets and transforms into nanoparticles. The results support the similarities between chemical vapor deposition processes for graphene, graphite, and CNT.

  17. Influence of Mo on the Fe:Mo:C nanocatalyst thermodynamics for single-walled carbon nanotube growth

    Science.gov (United States)

    Curtarolo, Stefano; Awasthi, Neha; Setyawan, Wahyu; Jiang, Aiqin; Bolton, Kim; Tokune, Toshio; Harutyunyan, Avetik R.

    2008-08-01

    We explore the role of Mo in Fe:Mo nanocatalyst thermodynamics for low-temperature chemical-vapor deposition growth of single-walled carbon nanotubes (SWCNTs). By using the size-pressure approximation and ab initio modeling, we prove that for both Fe-rich ( ˜80% Fe or more) and Mo-rich ( ˜50% Mo or more) Fe:Mo clusters, the presence of carbon in the cluster causes nucleation of Mo2C . This enhances the activity of the particle since it releases Fe, which is initially bound in a stable Fe:Mo phase, so that it can catalyze SWCNT growth. Furthermore, the presence of small concentrations of Mo reduces the lower size limit of low-temperature steady-state growth from ˜0.58nm for pure Fe particles to ˜0.52nm . Our ab initio-thermodynamic modeling explains experimental results and establishes a direction to search for better catalysts.

  18. Controlled growth, characterization and thermodynamic behavior of bismuth–tin nanostructures sheathed in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Namjo, E-mail: njjeong@kier.re.kr [Energy Materials Convergence Research Department, Korea Institute of Energy Research, 71-2, Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Jeju Global Research Center, Korea Institute of Energy Research, 200, Haemajihaean-ro, Gujwa-eup, Jeju Special Self-Governing Province 695-971 (Korea, Republic of); Hwang, Kyo Sik; Yang, SeungCheol [Jeju Global Research Center, Korea Institute of Energy Research, 200, Haemajihaean-ro, Gujwa-eup, Jeju Special Self-Governing Province 695-971 (Korea, Republic of); Lee, Soon-pung [Energy Materials Convergence Research Department, Korea Institute of Energy Research, 71-2, Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2014-03-01

    We report the controlled synthesis of bismuth–tin (Bi–Sn) nanostructures sheathed in graphitic shells that resemble carbon nanotubes (CNTs). Our approach is based on a simple catalytic chemical vapor deposition over a mixture of Bi{sub 2}O{sub 3} and SnO{sub 2} supplied as starting materials. Shape control of the nanostructures strongly relies on the weight ratio of Bi{sub 2}O{sub 3} and SnO{sub 2}. Sheathed nanoparticles and nanorods are formed at SnO{sub 2} to Bi{sub 2}O{sub 3} weight ratios of less than 4:1. They are composed of two separate crystals: rhombohedral Bi and tetragonal Sn{sub 19}Bi crystals. On the other hand, the sheathed nanowires are formed at SnO{sub 2} to Bi{sub 2}O{sub 3} weight ratios above 4:1. The nanowires have only tetragonal Sn{sub 19}Bi structure with a diameter of approximately 100 nm. Elementary analyses support the core/shell heterostructure of the resulting products. A favorable temperature for the Sn-rich Sn{sub 19}Bi nanowires is in the range of 700–800 °C, more specifically around 750 °C. Thermodynamic analysis reveals that the CNTs play a significant role in the protection of the Bi–Sn nanostructures during phase transition by temperature change. This simple and reproducible method may be extended to the fabrication of similar binary or ternary nanostructures. - Highlights: • Controlled growth of Bi–Sn nanostructures sheathed in CNTs relies on MSnO{sub 2}/MBi{sub 2}O{sub 3}. • Growth mechanism is based on catalytic reaction of C{sub 2}H{sub 2} over an oxide mixture. • Nanoparticles and nanorods consist of rhombohedral Bi and tetragonal Sn{sub 19}Bi. • A favorable temperature for the Sn{sub 19}Bi nanowires is in the range of 700–800 °C. • CNT acts as a protective barrier during phase change of the Bi–Sn nanostructures.

  19. Nanocomposite scaffold for chondrocyte growth and cartilage tissue engineering: effects of carbon nanotube surface functionalization.

    Science.gov (United States)

    Chahine, Nadeen O; Collette, Nicole M; Thomas, Cynthia B; Genetos, Damian C; Loots, Gabriela G

    2014-09-01

    The goal of this study was to assess the long-term biocompatibility of single-wall carbon nanotubes (SWNTs) for tissue engineering of articular cartilage. We hypothesized that SWNT nanocomposite scaffolds in cartilage tissue engineering can provide an improved molecular-sized substrate for stimulation of chondrocyte growth, as well as structural reinforcement of the scaffold's mechanical properties. The effect of SWNT surface functionalization (-COOH or -PEG) on chondrocyte viability and biochemical matrix deposition was examined in two-dimensional cultures, in three-dimensional (3D) pellet cultures, and in a 3D nanocomposite scaffold consisting of hydrogels+SWNTs. Outcome measures included cell viability, histological and SEM evaluation, GAG biochemical content, compressive and tensile biomechanical properties, and gene expression quantification, including extracellular matrix (ECM) markers aggrecan (Agc), collagen-1 (Col1a1), collagen-2 (Col2a1), collagen-10 (Col10a1), surface adhesion proteins fibronectin (Fn), CD44 antigen (CD44), and tumor marker (Tp53). Our findings indicate that chondrocytes tolerate functionalized SWNTs well, with minimal toxicity of cells in 3D culture systems (pellet and nanocomposite constructs). Both SWNT-PEG and SWNT-COOH groups increased the GAG content in nanocomposites relative to control. The compressive biomechanical properties of cell-laden SWNT-COOH nanocomposites were significantly elevated relative to control. Increases in the tensile modulus and ultimate stress were observed, indicative of a tensile reinforcement of the nanocomposite scaffolds. Surface coating of SWNTs with -COOH also resulted in increased Col2a1 and Fn gene expression throughout the culture in nanocomposite constructs, indicative of increased chondrocyte metabolic activity. In contrast, surface coating of SWNTs with a neutral -PEG moiety had no significant effect on Col2a1 or Fn gene expression, suggesting that the charged nature of the -COOH surface

  20. Post-CMOS wafer level growth of carbon nanotubes for low-cost microsensors-a proof of concept

    Energy Technology Data Exchange (ETDEWEB)

    Santra, Sumita; Guha, Prasanta K; Zhong, Guofang; Robertson, John; Milne, William I; Udrea, Florin [Engineering Department, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Ali, Syed Z [Cambridge CMOS Sensors Ltd, Wellington House, East Road, Cambridge CB1 1BH (United Kingdom); Covington, James A; Gardner, Julian W, E-mail: ss778@cam.ac.uk [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2010-12-03

    Here we demonstrate a novel technique to grow carbon nanotubes (CNTs) on addressable localized areas, at wafer level, on a fully processed CMOS substrate. The CNTs were grown using tungsten micro-heaters (local growth technique) at elevated temperature on wafer scale by connecting adjacent micro-heaters through metal tracks in the scribe lane. The electrical and optical characterization show that the CNTs are identical and reproducible. We believe this wafer level integration of CNTs with CMOS circuitry enables the low-cost mass production of CNT sensors, such as chemical sensors.

  1. Growth and structural discrimination of cortical neurons on randomly oriented and vertically aligned dense carbon nanotube networks

    Directory of Open Access Journals (Sweden)

    Christoph Nick

    2014-09-01

    Full Text Available The growth of cortical neurons on three dimensional structures of spatially defined (structured randomly oriented, as well as on vertically aligned, carbon nanotubes (CNT is studied. Cortical neurons are attracted towards both types of CNT nano-architectures. For both, neurons form clusters in close vicinity to the CNT structures whereupon the randomly oriented CNTs are more closely colonised than the CNT pillars. Neurons develop communication paths via neurites on both nanoarchitectures. These neuron cells attach preferentially on the CNT sidewalls of the vertically aligned CNT architecture instead than onto the tips of the individual CNT pillars.

  2. Iron-carbide cluster thermal dynamics for catalyzed carbon nanotube growth

    Science.gov (United States)

    Ding, Feng; Bolton, Kim; Rosén, Arne

    2004-07-01

    Molecular dynamics simulations have been used to study the thermal behavior of FeN-mCm clusters where N, the total number of atoms, extends up to 2400. Comparison of the computed results with experimental data shows that the simulations yield the correct trends for the liquid-solid region of the iron-carbide phase diagram as well as the correct dependence of cluster melting point as a function of cluster size. The calculation indicates that, when carbon nanotubes (CNTs) are grown on large (>3-4 nm) catalyst particles at low temperatures (melting of the cluster. .

  3. Low temperature growth of carbon nanotubes on printing electrodes by MPCVD

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.-C. [Department of Materials Science and Engineering, National Chiao Tung University, Taiwan (China) and Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China)]. E-mail: northnose@itri.org.tw; Chen, C.-F. [Department of Materials Science and Engineering, National Chiao Tung University, Taiwan (China); Chiang, J.-S. [Union Chemica Laboratories (UCL), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan, 310 (China); Hwang, C.-L. [Union Chemica Laboratories (UCL), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan, 310 (China); Chang, Y.-Y. [Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China); Lee, C.-C. [Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China)

    2006-03-01

    In this work, combination of screen-printing process and microwave plasma enhanced chemical vapor deposition system (MPCVD) was applied to fabricate patterned carbon nanotubes (CNTs) on the cathode electrodes on glass substrates. Solution based Ni catalyst was well-mixed with Ag powders and organic binder materials to form screen printed paste. CNTs were then grown under the atmosphere of CH{sub 4}/H{sub 2} gas mixture below 550 deg. C. In the field emission measurement, the turn-on field was 3.2 V/{mu}m and uniform electron emission image was also observed.

  4. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jun; Yao Zhiwen [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Tang Changyu [Department of Polymer Science and Materials, Sichuan University (China); Darvell, B.W. [Dental Materials Science, Faculty of Dentistry, University of Hong Kong (Hong Kong); Zhang Hualin; Pan Lingzhan; Liu Jingsong [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China); Chen Zhiqing, E-mail: yangj0710@gmail.com [State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, No 14, 3rd Section South People' s Road, Chengdu 610041 (China)

    2009-07-30

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  5. Growth, spectroscopy and utilisation of novel low dimensional nanostructures: carbon nanotubes and quantum dots

    OpenAIRE

    Bourdakos, Konstantinos Nikolaos

    2008-01-01

    The work presented in this thesis deals with two important low dimensional nanostructures: carbon nanotubes (CNTs) and quantum dots (QDs). In the part of the work related to CNTs a novel method for growing CNTs without the need of metal catalyst is presented. The as produced CNTs were grown by means of chemical vapour deposition on Si-Ge islands and on Ge dots grown with the Stransky — Krastanow method on top of silicon substrates. Through rigorous characterisation products of the method w...

  6. Carbon Nanotube Purification and Functionalization

    Science.gov (United States)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  7. Catalytic growth of single-, double-, and multi-walled carbon nanotubes and studies of their potential applications

    Science.gov (United States)

    Kayastha, Vijaya Kumar

    Catalytic growth of carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) was investigated, and role of various growth parameters on the CNT growth rate, density and structures was identified. A unified growth model was proposed which involves dissociative adsorption of acetylene on catalyst particles, and vapor-liquid-solid mechanism. According to it, balance between decomposition of C2H2 molecules on the catalyst surface, and diffusion of released carbon atoms into the catalyst particles is the key step towards the continuous growth of CNTs. Guided by our growth model, we demonstrated the growth of ultra-high dense vertically aligned multi-walled as well as rarely reported vertically aligned single-walled and double-walled CNTs. Post-growth manipulation and purification of CNTs by using AC electric field (dielectrophoresis) were investigated. Deeper understanding on the roles of the applied field strength and AC frequency was achieved. Increasing the electric field enhances the density of aligned nanotubes while increasing frequency enhances the dispersion, and hence the degree of alignment of CNTs, but reduces the nanotube density. CNTs were placed across a pair of electrodes with control of density and degree of alignment. Individual CNTs were successfully placed on an AFM tip. We investigated electron field emission from various types of CNT films and found that graphitic order of the CNTs is a major intrinsic factor which affects the emission current stability. Due to superior structural order, MWCNTs grown by thermal CVD have better emission stability than those grown by plasma enhanced CVD. These findings were explained by introducing a concept of emission current-induced dislocation and electron trapping effects, in which the dislocations induced in CNTs, and thus the electron transport along the CNTs prior to electron tunneling through them depend on the graphitic order of the CNTs. MWCNTs were successfully integrated into 2D and 3D carbon

  8. The role of catalytic nanoparticle pretreatment on the growth of vertically aligned carbon nanotubes by hot-filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Gohier, Aurélien; Bourée, Jean Eric; Châtelet, Marc; Cojocaru, Costel-Sorin, E-mail: costel-sorin.cojocaru@polytechnique.edu

    2015-01-30

    The effect of atomic hydrogen assisted pre-treatment on the growth of vertically aligned carbon nanotubes using hot-filament chemical vapor deposition was investigated. Iron nanoparticle catalysts were formed on an aluminum oxide support layer by spraying of iron chloride salt solutions as catalyst precursor. It is found that pre-treatment time and process temperature tune the density as well as the shape and the structure of the grown carbon nanotubes. An optimum pre-treatment time can be found for the growth of long and well aligned carbon nanotubes, densely packed to each other. To provide insight on this behavior, the iron catalytic nanoparticles formed after the atomic hydrogen assisted pre-treatment were analyzed by atomic force microscopy. The relations between the size and the density of the as-formed catalyst and the as-grown carbon nanotube's structure and density are discussed. - Highlights: • Effect of the atomic hydrogen assisted pre-treatment on the growth of VACNT using hot-filament CVD. • Pre-treatment time and process temperature tune the density, the shape and the structure of the CNTs. • Correlations between size and density of the as-formed catalyst and the CNT’s structure and density. • Carbon nanotubes synthesized at low temperature down to 500 °C using spayed iron chloride salts. • Density of the CNT carpet adjusted by catalytic nanoparticle engineering.

  9. Carbon nanotube network varactor

    Science.gov (United States)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  10. Carbon nanotube IR detectors (SV)

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  11. Carbon nanotube core graphitic shell hybrid fibers.

    Science.gov (United States)

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  12. Gas dynamic and time resolved imaging studies of single-wall carbon nanotubes growth in the laser ablation process

    Science.gov (United States)

    Sen, Rahul; Suzuki, S.; Kataura, H.; Achiba, Y.

    2001-10-01

    Single-wall carbon nanotubes (SWNTs) were synthesized by laser ablation of Ni-Co-graphite composite targets at 1200 °C under flowing argon. The effects of the temperature gradient near the target and the gas flow rate on the diameter distribution of SWNTs were studied in order to understand their growth dynamics. The diameter distribution of the SWNTs, analyzed by Raman spectroscopy, was dependent on the gas flow rate when there was a temperature gradient around the target. Time resolved scattering images from the ablated species at different flow rates indicated that velocities of backward moving species increased with increasing flow rate. These findings are used to estimate the time required for nucleation and the growth of SWNTs.

  13. Influence of growth time on field emission properties from carbon nanotubes deposited on arrayed nanoporous silicon pillars

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Weifen, E-mail: gingerwfj@yahoo.com.cn [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Hao Haoshan [Department of Mathematical and Physical Sciences, Henan Institute of Engineering, Zhengzhou 451191 (China); Wang Yusheng; Xu Lei; Zhang Tianjie [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China)

    2011-05-15

    We investigated the influence of growth time on field emission properties of multi-walled carbon nanotubes deposited on silicon nanoporous pillar array (MWCNTs/Si-NPA), which were fabricated by thermal chemical vapour deposition at 800 deg. C for 5, 15 and 25 min respectively, to better understand the origins of good field emission properties. The results showed that the MWCNTs/Si-NPA grown for 15 min had the highest field emission efficiency of the three types of samples. Morphologies of the products were examined by field-emission scanning electron microscope, and the excellent field emission performance was attributed not only to the formation of a nest array of multi-walled carbon nanotubes, which would largely reduce the electrostatic shielding among the emitters and resulted in a great enhancement factor, but also to the medium MWCNTs density films, there was an ideal compromise between the emitter density and the intertube distance, which also could effectively avoid electrostatic shielding effects, along with a high emitter density.

  14. Dynamic study of carbon nanotube growth and catalyst morphology evolution during acetylene decomposition on Co/SBA-15 in an environmental TEM

    DEFF Research Database (Denmark)

    s Aires, F. J. Cadete Santo; Epicier, T.; Wagner, Jakob Birkedal;

    2012-01-01

    In situ studies of micro- and nano-objects in their characteristic environment have been performed ever since the early days of electron microscopy [1]. Over several decades the in situ observation of the synthesis of filamentous carbon (nanotubes/nanofilaments) during hydrocarbon decomposition has...... been one of the most popular topics [2] for investigation in the environmental transmission electron microscope (ETEM). In this work we study the growth of carbon nanotubes (CNTs) by the decomposition of acetylene on Co nanoparticles inserted into mesoporous silicas (SBA-15) using both conventional...... post mortem TEM measurements and real-time in situ ETEM observations. In situ observation of the formation of the carbon nanotubes was performed in an FEI Titan 80-300 ETEM equipped with an objective lens spherical aberration corrector [3]. Prior to acetylene decomposition, the catalyst nanoparticles...

  15. Teslaphoresis of Carbon Nanotubes.

    Science.gov (United States)

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  16. Studies of Carbon Nanotubes

    Science.gov (United States)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  17. Luminescence of carbon nanotube bulbs

    Institute of Scientific and Technical Information of China (English)

    LI ChuanGang; WU DeHai; WANG KunLin; WEI JinQuan; WEI BingQing; ZHU HongWei; WANG ZhiCheng; LUO JianBin; LIU WenJin; ZHENG MingXin

    2007-01-01

    Carbon nanotube (CNT) bulbs made of decimeter-scale double-walled carbon nanotube (DWCNT) strands and films were fabricated and their luminescence properties, including the lighting efficiency, voltage-current relation and thermal stability were investigated. The results show that the DWCNT bulb has a comparable spectrum of visible light with tungsten bulb and its average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400-2300 K). The nanotube filaments show both resistance and thermal stability over a large temperature region. No obvious damage was found for a nanotube bulb illuminating at 2300 K for more than 24 hours in vacuum.

  18. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  19. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes.

    Science.gov (United States)

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury

    2010-08-01

    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  20. Synthesis of Aligned Carbon Nanotubes by Thermal Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Gang; ZHOU Ming; MA Weiwei; CAI Lan

    2009-01-01

    Single crystal silicon was found to be very beneficial to the growth of aligned carbon nanotubes by chemical vapor deposition with C2H2 as carbon source. A thin film of Ni served as catalyst was deposited on the Si substrate by the K575X Peltier Cooled High Resolution Sputter Coater before growth. The growth properties of carbon nanotubes were studied as a function of the Ni catalyst layer thickness. The diameter, growth rate and areal density of the carbon nanotubes were controlled by the initial thickness of the catalyst layer. Steric hindrance between nanotubes forces them to grow in well-aligned manner at an initial stage of growth. Transmission electron microscope analysis revealed that nanotubes grew by a tip growth mechanism.

  1. Polymerization initated at sidewalls of carbon nanotubes

    Science.gov (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

    2011-01-01

    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  2. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2013-01-01

    Full Text Available This paper compares between the methods of growing carbon nanotubes (CNTs on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD techniques for growing CNTs on diamond: thermal CVD (T-CVD, microwave plasma-enhanced CVD (MPE-CVD, and floating catalyst thermal CVD (FCT-CVD. Scanning electron microscopy (SEM and high-resolution transmission electron microscopy (TEM were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining the ID/IG peak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

  3. Hydroxyapatite growth on multiwall carbon nanotubes grown on titanium fibers from a titanium sheet

    KAUST Repository

    Chetibi, Loubna

    2013-09-27

    Nano-hydroxyapatite (HA) was grown on functionalized multiwalled carbon nanotubes (MWCNTs) deposited on TiO2 nanofibers (NFs) that were hydrothermally grown on Ti metal sheets. The HA was electrochemically grown on the MWCNTs/TiO2 porous layer. It was found that the HA grows on the MWCNTs/TiO2 NFs in the form of dense coating with nanorice grain-shaped. The incorporation of MWCNTs between HA and TiO2 NFs has led to higher adhesion strength as measured by micro-scratching test indicating the benefit of MWCNTs on the improving the bonding strength of HA layer. The obtained coatings exhibit excellent corrosion resistance in simulated body fluid. It is expected that this simple route for preparing the new HA/MWCNTs/TiO2/Ti-layered structure might be used not only in the biomedical field, but also in catalysis and biological sensing among others. © 2013 Springer Science+Business Media New York.

  4. Gas-Phase Growth of Heterostructures of Carbon Nanotubes and Bimetallic Nanowires

    Directory of Open Access Journals (Sweden)

    Whi Dong Kim

    2011-01-01

    Full Text Available A simple, inexpensive, and viable method for growing multiple heterostructured carbon nanotubes (CNTs over the entire surface of Ni-Al bimetallic nanowires (NWs in the gas phase was developed. Polymer-templated bimetallic nitrate NWs were produced by electrospinning in the first step, and subsequent calcination resulted in the formation of bimetallic oxide NWs by thermal decomposition. In the second step, free-floating bimetallic NWs were produced by spray pyrolysis in an environment containing hydrogen gas as a reducing gas. These NWs were continuously introduced into a thermal CVD reactor in order to grow CNTs in the gas phase. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and Raman spectrometry analyses revealed that the catalytic Ni sites exposed in the non-catalytic Al matrix over the entire surface of the bimetallic NWs were seeded to radially grow highly graphitized CNTs, which resembled “foxtail” structures. The grown CNTs were found to have a relatively uniform diameter of approximately 10±2 nm and 10 to 15 walls with a hollow core. The average length of the gas-phase-grown CNTs can be controlled between 100 and 1000 nm by adjusting the residence time of the free-floating bimetallic NWs in the thermal CVD reactor.

  5. Directional neurite growth using carbon nanotube patterned substrates as a biomimetic cue

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min Jee; Nam, Yoonkey [Department of Bio and Brain Engineering, KAIST, Daejeon (Korea, Republic of); Namgung, Seon; Hong, Seunghun, E-mail: seunghun@snu.ac.kr, E-mail: ynam@kaist.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

    2010-06-11

    Researchers have made extensive efforts to mimic or reverse-engineer in vivo neural circuits using micropatterning technology. Various surface chemical cues or topographical structures have been proposed to design neuronal networks in vitro. In this paper, we propose a carbon nanotube (CNT)-based network engineering method which naturally mimics the structure of extracellular matrix (ECM). On CNT patterned substrates, poly-L-lysine (PLL) was coated, and E18 rat hippocampal neurons were cultured. In the early developmental stage, soma adhesion and neurite extension occurred in disregard of the surface CNT patterns. However, later the majority of neurites selectively grew along CNT patterns and extended further than other neurites that originally did not follow the patterns. Long-term cultured neuronal networks had a strong resemblance to the in vivo neural circuit structures. The selective guidance is possibly attributed to higher PLL adsorption on CNT patterns and the nanomesh structure of the CNT patterns. The results showed that CNT patterned substrates can be used as novel neuronal patterning substrates for in vitro neural engineering.

  6. Carbon Nanotube Biosensors

    Directory of Open Access Journals (Sweden)

    Carmen-Mihaela eTilmaciu

    2015-10-01

    Full Text Available Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  7. A phenomenological model for selective growth of semiconducting single-walled carbon nanotubes based on catalyst deactivation.

    Science.gov (United States)

    Sakurai, Shunsuke; Yamada, Maho; Sakurai, Hiroko; Sekiguchi, Atsuko; Futaba, Don N; Hata, Kenji

    2016-01-14

    A method for the selective semiconducting single-walled carbon nanotube (SWCNT) growth over a continuous range from 67% to 98%, within the diameter range of 0.8-1.2 nm, by the use of a "catalyst conditioning process" prior to growth is reported. Continuous control revealed an inverse relationship between the selectivity and the yield as evidenced by a 1000-times difference in yield between the highest selectivity and non-selectivity. Further, these results show that the selectivity is highly sensitive to the presence of a precise concentration of oxidative and reductive gases (i.e. water and hydrogen), and the highest selectivity occurred along the border between the conditions suitable for high yield and no-growth. Through these results, a phenomenological model has been constructed to explain the inverse relationship between yield and selectivity based on catalyst deactivation. We believe our model to be general, as the fundamental mechanisms limiting selective semiconducting SWCNT growth are common to the previous reports of limited yield. PMID:26660858

  8. Method for synthesizing carbon nanotubes

    Science.gov (United States)

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  9. Nitrogen in highly crystalline carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ducati, C; Koziol, K; Stavrinadis, A; Friedrichs, S; Windle, A H; Midgley, P A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2006-02-22

    Multiwall carbon nanotubes (MWCNTs) with an unprecedented degree of internal order were synthesised by chemical vapour deposition (CVD) adding a nitrogen-containing compound to the hydrocarbon feedstock. Ferrocene was used as the metal catalyst precursor. The remarkable crystallinity of these nanotubes lies both in the isochirality and in the crystallographic register of their walls, as demonstrated by electron diffraction and high resolution electron microscopy experiments. High resolution transmission electron microscopy analysis shows that the walls of the nanotubes consist of truncated stacked cones, instead of perfect cylinders, with a range of apex angles that appears to be related to the nitrogen concentration in the synthesis process. The structure of armchair, zigzag and chiral nanotubes is modelled and discussed in terms of density of topological defects, providing an interesting comparison with our microscopy experiments. A growth mechanism based on the interplay of base- and tip-growth is proposed to account for our experimental observations.

  10. Morphology, structure and Raman scattering of carbon nanotubes produced by using mesoporous materials

    Institute of Scientific and Technical Information of China (English)

    解思深; 李文治; 王超英; 徐丽雯; 张昊; 张云; 钱露茜

    1997-01-01

    Carbon nanotubes were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates.The effect of substrates on the growth,morphology and structure of carbon nanotubes were investigated.Aligned carbon nanotubes with high density and purity were achieved by CVD on mesoporous silica substrate.The Raman scattering of aligned carbon nanotubes was carried out,and the dependence of the phonon properties on the mi-crostructure of the nanotubes has been discussed.

  11. Automated circuit fabrication and direct characterization of carbon nanotube vibrations.

    Science.gov (United States)

    Zeevi, G; Shlafman, M; Tabachnik, T; Rogachevsky, Z; Rechnitz, S; Goldshtein, I; Shlafman, S; Gordon, N; Alchanati, G; Itzhak, M; Moshe, Y; Hajaj, E M; Nir, H; Milyutin, Y; Izraeli, T Y; Razin, A; Shtempluck, O; Kotchtakov, V; Yaish, Y E

    2016-01-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion. PMID:27396506

  12. Modeling of HiPco Process for Carbon Nanotube Production

    Science.gov (United States)

    Gokcen, T.; Dateo, C. E.; Meyyappan, M.; Colbert, D. T.; Smith, D. T.; Smith, K.; Smalley, R. E.; Arnold, James O. (Technical Monitor)

    2000-01-01

    High-pressure carbon monoxide (HiPco) reactor, developed at Rice University, is used to produce single-walled carbon nanotubes (SWNT) from gas-phase reactions of iron carbonyl and nickel carbonyl in carbon monoxide at high pressures (10 - 100 atm). Computational modeling is used to better understand the HiPco process. In the present model, decomposition of the precursor, metal cluster formation and growth, and carbon nanotube growth are addressed. Decomposition of precursor molecules is necessary to initiate metal cluster formation. The metal clusters serve as catalysts for carbon nanotube growth. Diameter of metal clusters and number of atoms in these clusters are some of the essential information for predicting carbon nanotube formation and growth, which is then modeled by Boudouard reaction (2CO ---> C(s) + CO2) with metal catalysts. The growth kinetic model is integrated with a two-dimensional axisymmetric reactor flow model to predict reactor performance.

  13. Synthesis of Carbon Nanotubes Using Sol Gel Route

    Science.gov (United States)

    Abdel-Fattah, Tarek

    2002-12-01

    Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

  14. In situ growth of carbon nanotube wrapped Si composites as anodes for high performance lithium ion batteries.

    Science.gov (United States)

    Zhou, Jianbin; Lan, Yang; Zhang, Kailong; Xia, Guoliang; Du, Jin; Zhu, Yongchun; Qian, Yitai

    2016-03-01

    The composites of carbon nanotube wrapped Si particles (CNTWS) were synthesized in situ by using the catalytic chemical vapor deposition (CCVD) method. In this process, carbon nanotubes were produced in situ to wrap Si by the catalysis action of nascent Cu* under an acetylene atmosphere at a relatively low temperature of 400 °C, in which nascent Cu* was created by the reaction between Si particles and CuCl synchronously. The weight ratio of Si/C in CNTWS is 0.76/0.24. As anode materials for lithium ion batteries, the CNTWS composites exhibit a reversible discharge capacity of 1031.1 mA h g(-1) at 1.8 A g(-1) after 500 cycles, and 868.2 mA h g(-1) at 10.0 A g(-1). The high electrochemical performance of CNTWS composites is associated with the in situ formed carbon nanotubes. PMID:26875542

  15. DFT study of Fe-Ni core-shell nanoparticles: Stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhimin; Wang, Qiang, E-mail: wangqiang@njtech.edu.cn; Shan, Xiaoye; Zhu, Hongjun, E-mail: zhuhj@njtech.edu.cn [Department of Applied Chemistry, College of Science, Nanjing Tech University, Nanjing 211816 (China); Li, Wei-qi [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Chen, Guang-hui [Department of Chemistry, Shantou University, Shantou, Guangdong 515063 (China)

    2015-02-21

    Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.

  16. CoPt/CeO2 catalysts for the growth of narrow diameter semiconducting single-walled carbon nanotubes.

    Science.gov (United States)

    Tang, Lei; Li, Taotao; Li, Chaowei; Ling, Lin; Zhang, Kai; Yao, Yagang

    2015-12-14

    For the application of single-walled carbon nanotubes (SWNTs) in nanoelectronic devices, effective techniques for the growth of semiconducting SWNTs (s-SWNTs) with a specific diameter are still a great challenge. Herein, we report a facile strategy for the selective growth of narrow diameter distributed s-SWNTs using CoPt/CeO2 catalysts. The addition of Pt into a Co catalyst dramatically reduces the diameter distributions and even the chirality distributions of the as-grown SWNTs. Oxygen vacancies that are provided by mesoporous CeO2 are responsible for creating an oxidative environment to in situ etch metallic SWNTs (m-SWNTs). Atomic force microscope (AFM) and Raman spectroscopy characterizations indicate a narrow diameter distribution of 1.32 ± 0.03 nm and the selective growth of s-SWNTs to 93%, respectively. In addition, electronic transport measurements also confirm that the Ion/Ioff ratio is mainly in the order of ∼10(3). This work provides an effective strategy for the facile fabrication of narrow diameter distributed s-SWNTs, which will be beneficial to fundamental research and the broad application of SWNTs for future nanoelectronics. PMID:26553394

  17. Improved Method of Purifying Carbon Nanotubes

    Science.gov (United States)

    Delzeit, Lance D.

    2004-01-01

    An improved method of removing the residues of fabrication from carbon nanotubes has been invented. These residues comprise amorphous carbon and metal particles that are produced during the growth process. Prior methods of removing the residues include a variety of processes that involved the use of halogens, oxygen, or air in both thermal and plasma processes. Each of the prior methods entails one or more disadvantages, including non-selectivity (removal or damage of nanotubes in addition to removal of the residues), the need to dispose of toxic wastes, and/or processing times as long as 24 hours or more. In contrast, the process described here does not include the use of toxic chemicals, the generation of toxic wastes, causes little or no damage to the carbon nanotubes, and involves processing times of less than 1 hour. In the improved method, purification is accomplished by flowing water vapor through the reaction chamber at elevated temperatures and ambient pressures. The impurities are converted to gaseous waste products by the selective hydrogenation and hydroxylation by the water in a reaction chamber. This process could be performed either immediately after growth or in a post-growth purification process. The water used needs to be substantially free of oxygen and can be obtained by a repeated freeze-pump-thaw process. The presence of oxygen will non-selectively attach the carbon nanotubes in addition to the amorphous carbon.

  18. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  19. Carbon nanotube biconvex microcavities

    Science.gov (United States)

    Butt, Haider; Yetisen, Ali K.; Ahmed, Rajib; Yun, Seok Hyun; Dai, Qing

    2015-03-01

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2-3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  20. Carbon nanotube optical mirrors

    Science.gov (United States)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  1. Functionalization of Carbon Nanotubes

    Science.gov (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  2. Carbon nanotube biconvex microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Haider, E-mail: h.butt@bham.ac.uk; Ahmed, Rajib [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom Street, Boston, Massachusetts 02114 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  3. Enhanced Carbon Nanotube Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  4. A new mechanism for carbon nanotube evolution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Key discoveries on the growth mechanism of carbon nanotubes(CNTs) have recently been achieved by CAS researcher ZHU Zhenping and his research group at the State Key Laboratory of Coal Conversion,the Institute of Coal Chemistry of CAS, funded by the National Natural Science Foundation of China and the CAS Bairen Program.

  5. A carbon nanotube-based sensing element

    Institute of Scientific and Technical Information of China (English)

    YANG Xing; ZHOU Zhao-ying; WU Ying; ZHANG Jin; ZHANG Ying-ying

    2007-01-01

    A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes,carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which are located on the two electrodes. The CNT-based sensing element is fabricated by CVD (chemical vapor deposition)-direct-growth on microelectrodes. The sensing model and measurement method of electromechanical property are also presented. Finally, the voltage-current characteristics are measured, which show that the CNT-based sensing element has good electrical properties.

  6. Effects of metal elements in catalytic growth of carbon nanotubes/graphene: A first principles DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingde; Croiset, Eric; Ricardez-Sandoval, Luis, E-mail: laricard@uwaterloo.ca

    2014-10-30

    Graphical abstract: - Highlights: • Role of metals in the catalytic growth of CNTs or graphene was studied using DFT. • The results explain why Ni-based catalyst is suitable for growing CNTs. • Cu based alloys, e.g. Cu{sub 8}Ni, are found appropriate catalyst for graphene synthesis. - Abstract: Role of metals in the catalytic Chemical Vapor Deposition (CVD) growth of carbon nanotubes (CNTs) or graphene was investigated using DFT. Crucial processes involved in the growth of CNTs/graphene: methane dissociation to produce C, C diffusion and nucleation kinetics were studied on the (1 1 1) surface of different transition metals, i.e., Fe, Co, Ni, and Cu. Based on the DFT calculation results, the present study explains why Ni-based catalyst is a suitable CVD substrate for growing CNTs: it has a moderate reactivity towards methane dissociation; low energy barrier for C atom surface diffusion, which makes C to diffuse easily to the metal/CNTs edges and contribute to CNTs growth; relatively high nucleation barriers, making it more resistant for deactivation caused by the cover of carbon clusters. Meanwhile, this study also shows that Cu may be an appropriate catalyst for graphene synthesis due to the particularly low diffusion and nucleation barriers of C atoms on Cu, which suggest that C atoms tend to be more uniformly distributed and nucleate easily on the Cu surface. Key limitation of Cu is the low reactivity of this metal towards methane dissociation. Since Fe and Ni are very reactive towards C-H bond breaking, Cu based alloys, e.g. Cu{sub 8}Ni, were proposed as a suitable catalyst for graphene production.

  7. Molybdenum Disulfide Sheathed Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xu Chun SONG; Zhu De XU; Yi Fan ZHENG; Gui HAN; Bo LIU; Wei Xiang CHEN

    2004-01-01

    Single and double layered MoS2-coated multiwalled carbon nanotubes (MWCNs) were successfully prepared by pyrolyzing (NH4)2MoS4-coated multiwalled carbon nanotubes in an H2 atmosphere at 900℃. MoS2-coated MWCNs would be expected to have different tribological and mechanical properties compared to MoS2, so it may have potential applications in many fields.

  8. Carbon nanotubes for coherent spintronics

    Directory of Open Access Journals (Sweden)

    F. Kuemmeth

    2010-03-01

    Full Text Available Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications.

  9. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  10. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K;

    2010-01-01

    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual......, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications....

  11. The Effect of Alumina and Magnesia Supported Germanium Nanoparticles on the Growth of Carbon Nanotubes in the Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    Ghazaleh Allaedini

    2015-01-01

    Full Text Available The effect of alumina and magnesia supported germanium (Ge nanoparticles on the synthesis of carbon nanotubes (CNTs using the chemical vapor deposition (CVD method in atmospheric pressure was investigated. The TEM micrographs confirmed the formation of carbon nanotubes, and the field emission scanning electron microscopy (FESEM analysis suggested a tip-growth mechanism for the grown carbon nanotubes. The X-ray diffraction (XRD pattern indicated a graphitic nature of the carbon nanotubes. The obtained CNTs using Ge nanoparticles supported by MgO resulted in a higher degree of graphitization than the CNTs obtained using Ge nanoparticles supported by Al2O3. Raman spectroscopy analysis of the CNTs confirmed the presence of radial breathing modes (RBM, which verified the formation of CNTs. High frequency Raman analysis demonstrated that the degree of graphitization of the synthesized CNTs using magnesia supported Ge nanoparticles is higher than that of the alumina supported Ge nanoparticles with the values of (ID/IG ratios equal to 0.45 and 0.73, respectively.

  12. Effect of substrate material on the growth and field emission characteristics of large-area carbon nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Ummethala, Raghunandan; Täschner, Christine; Leonhardt, Albrecht; Büchner, Bernd [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Wenger, Daniela; Tedde, Sandro F. [Siemens Healthcare GmbH, Technology Centre, Guenther-Scharowsky-Strasse 1, 91058 Erlangen (Germany); Eckert, Jürgen [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstrasse 12, A-8700 Leoben (Austria); Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben (Austria)

    2016-01-28

    Carbon nanotubes (CNTs) are a promising replacement for tungsten filaments as electron emitters in conventional x-ray sources, owing to their higher aspect ratio, superior mechanical stability, chemical inertness, and high electrical and thermal conductivities. Conditions for realizing the best emission behavior from CNTs have been formulated over the last few years. In this paper, we report the relatively less-investigated factor, namely, the influence of the nature of substrate material on the growth as well as field emission characteristics of large-area multiwalled CNTs for their practical application in medical x-ray sources. We compare the morphology of CNTs on a variety of substrates such as stainless steel, copper, molybdenum, graphite, few-layer graphene, and carbon nanowalls grown by thermal chemical vapor deposition following a simple drop-coating of catalyst. We find that CNTs grown on stainless steel and graphite show the best combination of emission characteristics under pulsed operation mode. These studies are helpful in selecting the optimum substrate material for field emission applications. Ex situ studies on field emission degradation of CNTs are presented towards the end.

  13. Role of negatively charged ions in plasma on the growth and field emission properties of spherical carbon nanotube tip

    Energy Technology Data Exchange (ETDEWEB)

    Tewari, Aarti; Walia, Ritu; Sharma, Suresh C. [Department of Physics, Maharaja Agrasen Institute of Technology, Sector-22, Rohini, Delhi-110086 (India)

    2012-01-15

    The role of negatively charged ions in plasma on growth (without catalyst) and field emission properties of spherical carbon nanotube (CNT) tip has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, negatively and positively charged ions, neutral atoms, and the energy balance of various species has been developed. Numerical calculations of the spherical CNT tip radius for different relative density of negatively charged ions {epsilon}{sub r}(=n{sub SF{sub 6{sup -}}}/n{sub C{sup +}}, where n{sub SF{sub 6{sup -}}} and n{sub C}{sup +} are the equilibrium densities of sulphur hexafluoride and carbon ions, respectively) have been carried out for the typical glow discharge plasma parameters. It is found that the spherical CNT tip radius decreases with {epsilon}{sub r} and hence the field emission of electrons from the spherical CNT tip increases. Some of our theoretical results are in accordance with the existing experimental observations.

  14. Effect of substrate material on the growth and field emission characteristics of large-area carbon nanotube forests

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) are a promising replacement for tungsten filaments as electron emitters in conventional x-ray sources, owing to their higher aspect ratio, superior mechanical stability, chemical inertness, and high electrical and thermal conductivities. Conditions for realizing the best emission behavior from CNTs have been formulated over the last few years. In this paper, we report the relatively less-investigated factor, namely, the influence of the nature of substrate material on the growth as well as field emission characteristics of large-area multiwalled CNTs for their practical application in medical x-ray sources. We compare the morphology of CNTs on a variety of substrates such as stainless steel, copper, molybdenum, graphite, few-layer graphene, and carbon nanowalls grown by thermal chemical vapor deposition following a simple drop-coating of catalyst. We find that CNTs grown on stainless steel and graphite show the best combination of emission characteristics under pulsed operation mode. These studies are helpful in selecting the optimum substrate material for field emission applications. Ex situ studies on field emission degradation of CNTs are presented towards the end

  15. Effect of hydrogen plasma irradiation of catalyst films on growth of carbon nanotubes filled with iron nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hideki, E-mail: sato@elec.mie-u.ac.jp; Kubonaka, Nobuo; Nagata, Atsushi; Fujiwara, Yuji [Graduate School of Engineering, Mie University, 1577 Kurima-machiya-cho, Tsu 514-8507 (Japan)

    2014-03-15

    Carbon nanotubes filled with iron (Fe-filled CNTs) show shape anisotropy on account of the high aspect ratio of magnetic nanowires, and are promising candidates for various applications, such as magnetic recording media, probes for scanning force microscopy, and medical treatment for cancer. The ability to appropriately control the magnetic properties of CNTs for those applications is desirable. In this study, the authors investigated magnetic properties of Fe-filled CNTs synthesized by thermal chemical vapor deposition for the purpose of tuning their coercivity. Here, the authors implemented hydrogen plasma irradiation of catalyst film that was previously deposited on a substrate as a catalyst layer. This treatment activates the catalyst film and thus enhances the growth of the Fe-filled CNTs. It was confirmed that the H{sub 2} plasma irradiation enhances the growth of the CNTs in terms of increasing their length and diameter compared to CNTs without irradiation. On the other hand, the coercivity of Fe-filled CNTs dropped to approximately half of those without H{sub 2} plasma irradiation. This is probably due to a decrease in the aspect ratio of the Fe nanowires, which results from the increase in their diameter. Furthermore, the crystal structure of the Fe nanowires may affect the coercivity.

  16. Conducting Polymer Nanostructures and Nanocomposites with Carbon Nanotubes: Hierarchical Assembly by Molecular Electrochemistry, Growth Aspects and Property Characterization.

    Science.gov (United States)

    Gupta, Sanju; Price, Carson; Heintzman, Eli

    2016-01-01

    Conducting (or π-conjugated) polymers are promising materials for preparing supramolecular nano-structures and nanocomposites. We report controlled nanostructure syntheses of polypyrrole (PPy) and poylaniline (PANi) via electropolymerization (i.e., in-situ electrochemical anodic oxidation). The density, shape, caliber and thickness of self-assembled PPy micro-containers are regulated by electrochemical potential window for H2 bubbles and number of cyclic voltammetric (potentiodynamic) scans. Likewise, we employed amperometry, chronopotentiometry and potentiodynamic modes using hydrochloric acid as oxidizing agent to prepare PANi nanoparticles and nanotubules. We present our findings from the viewpoint of molecular electrochemistry with growth kinetic aspects yielding mechanistic details (initially forming dimers and oligomers as nucleating agents followed by polymer growth). Also targeted is forming nanocomposites with functionalized single- and multi-walled carbon nanotubes (FSWCNTs and FMWCNTs) as reinforced agent to optimize structural and functional properties. All of these novel nanomaterials are characterized using a range of complementary techniques to establish microscopic structure-property-function relationship. PMID:27398466

  17. Controlled growth of carbon nanotube-graphene hybrid materials for flexible and transparent conductors and electron field emitters

    Science.gov (United States)

    Nguyen, Duc Dung; Tai, Nyan-Hwa; Chen, Szu-Ying; Chueh, Yu-Lun

    2012-01-01

    We report a versatile synthetic process based on rapid heating and cooling chemical vapor deposition for the growth of carbon nanotube (CNT)-graphene hybrid materials where the thickness of graphene and density of CNTs are properly controlled. Graphene films are demonstrated as an efficient barrier layer for preventing poisoning of iron nanoparticles, which catalyze the growth of CNTs on copper substrates. Based on this method, the opto-electronic and field emission properties of graphene integrated with CNTs can be remarkably tailored. A graphene film exhibits a sheet resistance of 2.15 kΩ sq-1 with a transmittance of 85.6% (at 550 nm), while a CNT-graphene hybrid film shows an improved sheet resistance of 420 Ω sq-1 with an optical transmittance of 72.9%. Moreover, CNT-graphene films are demonstrated as effective electron field emitters with low turn-on and threshold electric fields of 2.9 and 3.3 V μm-1, respectively. The development of CNT-graphene films with a wide range of tunable properties presented in this study shows promising applications in flexible opto-electronic, energy, and sensor devices.

  18. Carbon nanotube computer.

    Science.gov (United States)

    Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

    2013-09-26

    The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems.

  19. Developing Single-Wall Carbon Nanotubes into an Industrial Material through the Super-Growth CVD Method

    Science.gov (United States)

    Futaba, Don

    2013-03-01

    Since the discovery of the carbon nanotube (CNT) 20 years ago, extensive effort has been made to utilize their exceptional intrinsic properties toward industrial applications. However, availability has significantly thwarted these endeavors. In one section of my presentation, I will describe our efforts toward the economical mass-production of single-walled carbon nanotubes (SWCNT) based on the water-assisted chemical vapor deposition technique, from which highly efficient synthesis of vertically aligned SWCNTs grow from substrates (SWCNT forests). Further, I will discuss our work to promote the industrial use of SWCNTs as a member of the Technology Research Association for Single-Walled Carbon Nanotubes (TASC) (A consortium of five companies and AIST founded for the specific purpose of developing SWCNT industrial technology.) Specifically, I will present our progress on developing the technology for the synthetic control of SWCNTs and the development of standardized evaluation techniques for the purpose of understanding the relationship between the SWCNT forest structure, e.g. length, density, crystallinity, etc and the targeted property, e.g. conductivity, mechanical reinforcement, etc. Finally, I will present several examples of applications from composites to CNT-based devices. Technology Research Association for Single Wall Carbon Nanotubes (TASC), Japan

  20. Industrial compatible re-growth of vertically aligned multiwall carbon nanotubes by ultrafast pure oxygen purification process

    DEFF Research Database (Denmark)

    Bu, Ian Y.Y.; Hou, Kai; Engstrøm, Daniel Southcott

    2011-01-01

    Reproducible high-yield purification process of multiwalled carbon nanotubes (CNTs) was developed by thermal annealing in ultrapure oxygen. The optimized condition involves thermal annealing via a PID controlled heater in high purity oxygen at temperature of 450°C for 180s, which burns out amorph...

  1. Gaseous product mixture from Fischer-Tropsch synthesis as an efficient carbon feedstock for low temperature CVD growth of carbon nanotube carpets.

    Science.gov (United States)

    Almkhelfe, Haider; Carpena-Núñez, Jennifer; Back, Tyson C; Amama, Placidus B

    2016-07-21

    Low-temperature chemical vapor deposition (CVD) growth of carbon nanotube (CNT) carpets from Fe and Fe-Cu catalysts using a gaseous product mixture from Fischer-Tropsch synthesis (FTS-GP) as a superior carbon feedstock is demonstrated. This growth approach addresses a persistent issue of obtaining thick CNT carpets on temperature-sensitive substrates at low temperatures using a non-plasma CVD approach without catalyst pretreatment and/or preheating of the carbon feedstock. The efficiency of the process is evidenced by the highly dense, vertically aligned CNT structures from both Fe and Fe-Cu catalysts even at temperatures as low as 400 °C - a record low growth temperature for CNT carpets obtained via conventional thermal CVD. The grown CNTs exhibit a straight morphology with hollow interior and parallel graphitic planes along the tube walls. The apparent activation energies for CNT carpet growth on Fe and Fe-Cu catalysts are 0.71 and 0.54 eV, respectively. The synergistic effect of Fe and Cu show a strong dependence on the growth temperature, with Cu being more influential at temperatures higher than 450 °C. The low activation energies and long catalyst lifetimes observed are rationalized based on the unique composition of FTS-GP and Gibbs free energies for the decomposition reactions of the hydrocarbon components. The use of FTS-GP facilitates low-temperature growth of CNT carpets on traditional (alumina film) and nontraditional substrates (aluminum foil) and has the potential of enhancing CNT quality, catalyst lifetime, and scalability. PMID:27353432

  2. Probing Photosensitization by Functionalized Carbon Nanotubes

    Science.gov (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  3. Synthesis of Carbon Nanotube (CNT Composite Membranes

    Directory of Open Access Journals (Sweden)

    Dusan Losic

    2010-12-01

    Full Text Available Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT using chemical vapour deposition (CVD on the template of nanoporous alumina (PA membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm, and thickness (5–100 µm, was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDXS, high resolution transmission electron microscopy (HRTEM and x-ray diffraction (XRD. Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal used as model of hydrophilic transport molecule.

  4. Kondo physics in carbon nanotubes

    OpenAIRE

    Nygard, Jesper; Cobden, David Henry; Lindelof, Poul Erik

    2000-01-01

    The connection of electrical leads to wire-like molecules is a logical step in the development of molecular electronics, but also allows studies of fundamental physics. For example, metallic carbon nanotubes are quantum wires that have been found to act as one-dimensional quantum dots, Luttinger-liquids, proximity-induced superconductors and ballistic and diffusive one-dimensional metals. Here we report that electrically-contacted single-wall nanotubes can serve as powerful probes of Kondo ph...

  5. Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shumin; Zheng, Yudong, E-mail: zhengyudong@mater.ustb.edu.cn; Qiao, Kun [University of Science and Technology Beijing, School of Material Science and Engineering (China); Su, Lei [University of Science and Technology Beijing, School of Chemistry and Biological Engineering (China); Sanghera, Amendeep; Song, Wenhui [University College London, UCL Centre for Nanotechnology & Regenerative Medicine, Division of Surgery and Interventional Science (United Kingdom); Yue, Lina; Sun, Yi [University of Science and Technology Beijing, School of Material Science and Engineering (China)

    2015-12-15

    This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

  6. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained, lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However, experimental information obtained thus far on CNTs’ cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTs in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs’ cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  7. Cytotoxicity of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHU Ying; LI WenXin

    2008-01-01

    With large-scale production and application at large scale, carbon nanotubes (CNTs) may cause ad-verse response to the environment and human health. Thus, study on bio-effects and safety of CNTs has attracted great attention from scientists and governments worldwide. This report briefly summa-rizes the main results from the in vitro toxicity study of CNTs. The emphasis is placed on the descrip-tion of a variety of factors affecting CNTs cytotoxicity, including species of CNTs, impurities contained,lengths of CNTs, aspect ratios, chemical modification, and assaying methods of cytotoxicity. However,experimental information obtained thus far on CNTs' cytotoxicity is lacking in comparability, and some-times there is controversy about it. In order to assess more accurately the potential risks of CNTs to human health, we suggest that care should be taken for issues such as chemical modification and quantitative characterization of CNTa in cytotoxicity assessment. More importantly, studies on physical and chemical mechanisms of CNTs' cytotoxicity should be strengthened; assaying methods and evaluating criteria characterized by nanotoxicology should be gradually established.

  8. Growth of graphite film over the tops of vertical carbon nanotubes using Ni/Ti/Si substrate

    Institute of Scientific and Technical Information of China (English)

    Chia-chih Chuang; Wei-long Liu; Wen-jauh Chen; Jin-hua Huang

    2009-01-01

    A substrate with Ni/Ti/Si structure was used to grow vertical carbon nanotubes (CNTs) with a graphite film over CNT tops by thermal chemical vapor deposition with CH4 gas as carbon source.The carbon nanotubes and the substrate were character-ized by a field emission scanning electron microscope for the morphologies,a transmission electron microscope for the microstruc-tures,a Raman spectrograph for the crystallinity,and an Auger electron spectrometer for the depth distribution of elements.The re-sult shows that when the thickness ratio of Ni layer to Ti layer in substrate is about i,a graphite film with relatively good quality canbe formed on the CNT tops.

  9. Super-hydrophobic transparent surface by femtosecond laser micro-patterned catalyst thin film for carbon nanotube cluster growth

    Science.gov (United States)

    Tang, M.; Hong, M. H.; Choo, Y. S.; Tang, Z.; Chua, Daniel H. C.

    2010-11-01

    In this work, super-hydrophobic surfaces were fabricated by femtosecond laser micro-machining and chemical vapor deposition to constitute hybrid scale micro/nano-structures formed by carbon nanotube (CNT) clusters. Nickel thin-film microstructures, functioning as CNT growth catalyst, precisely control the distribution of the CNT clusters. To obtain minimal heat-affected zones, femtosecond laser was used to trim the nickel thin-film coating. Plasma treatment was subsequently carried out to enhance the lotus-leaf effect. The wetting property of the CNT surface is improved from hydrophilicity to super-hydrophobicity at an advancing contact angle of 161 degrees. The dynamic water drop impacting test further confirms its enhanced water-repellent property. Meanwhile, this super-hydrophobic surface exhibits excellent transparency with quartz as the substrate. This hybrid fabrication technique can achieve super-hydrophobic surfaces over a large area, which has potential applications as self-cleaning windows for vehicles, solar cells and high-rise buildings.

  10. Hybrid Composite of Polyaniline Containing Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Carbon nanotube-polyaniline hybrid material was synthesized by emulsion polymerization in-situ. The morphology of hybrid material was studied by TEM and X-ray diffraction. The conductivity of nanocomposite increases with the increasing of carbon nanotube content because of the new conductivity passageways formed by carbon nanotubes.

  11. Synthesis and Application of Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Qun Zeng; Zhenhua Li; Yuhong Zhou

    2006-01-01

    Owing to the unique structure, the superior physical and chemical properties, the super strong mechanical performances, and so on, carbon nanotubes have attracted the attention of researchers all over the world. In this article, the basic properties and the main production processes of carbon nanotubes are introduced in brief, and the progress of applied research for carbon nanotubes is reviewed.

  12. Dispersions of Carbon nanotubes in Polymer Matrices

    Science.gov (United States)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

    2010-01-01

    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  13. Aligned carbon nanotubes physics, concepts, fabrication and devices

    CERN Document Server

    Ren, Zhifeng; Wang, Yang

    2012-01-01

    This book surveys the physics and fabrication of carbon nanotubes and their applications in optics, electronics, chemistry and biotechnology. The text illustrates major fabrication methods in detail, particularly the most widely used PECVD growth techniques.

  14. Adsorption on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    DING Yi; YANG Xiao-bao; NI Jun

    2006-01-01

    Adsorption on single walled carbon nanotubes (SWCNTs) is a subject of growing experimental and theoretical interest.The possible adsorbed patterns of atoms and molecules on the single-walled carbon nanotubes vary with the diameters and chirality of the tubes due to the confinement.The curvature of the carbon nanotube surface enlarges the distance of the adsorbate atoms and thus enhances the stability of high coverage structures of adsorbate.There exist two novel high-coverage stable structures of potassium adsorbed on SWCNTs,which are not stable on graphite.The electronic properties of SWCNTs can be modified by adsorbate atoms and metal-semiconductor and semiconductor-semi-conductor transitions can be achieved by the doping of alkali atoms.

  15. Carbon nanotube-polymer composite actuators

    Science.gov (United States)

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  16. Preparation of carbon nanotubes by MPECVD

    International Nuclear Information System (INIS)

    Microwave plasma-enhanced chemical vapor deposition (MPECVD) method has been regarded as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the large area growth, the lower growth temperature, uniform heat distribution and the good control of the different growth parameters. In this work we present our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapor deposition MPECVD. Well aligned, curly and coiled carbon nanotubes have been prepared. We have investigated the effect of the different growth condition parameters such as type of the catalyst, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results were showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. There is a linear relation between the growth rate and the methane to hydrogen ratio. We found that the growth rate has a great dependence on the amount of methane. For example the growth rate varied from the value 1,34 μm/min when the methane flow rate was 10 sccm to more than 14 μm/min when the methane flow rate was raised to 50 sccm. This growth rate is greater than that reported in the literature. The effect of the gas pressure on the CNTs was also studied. The Raman spectra (excitation wavelength 473 nm) of all samples show D-band peak at around 1300 cm-1 and G-band peak at around 1580 cm-1, which indicate that our CNTs are multi wall CNTs (MWCNTs). The D-band and the G-band correspond to sp2 and sp3 carbon stretching modes relatively, and their intensity ratio is a measure of the amount of disorder in the CNTs. The D-band is known to be attributed to the carbonaceous particles, defects in the curved graphitic sheet and tube ends. It has been suggested that lower Ig/Id ratios and narrower first and second order D and G bands are suggestive of well-aligned NNTs. The photoluminescence PL

  17. Gears Based on Carbon Nanotubes

    Science.gov (United States)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  18. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.;

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries, enabled by sophisticated fabrication, have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two....... In single quantum dots defined in short lengths of nanotube, the energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are revealed by Coulomb blockade spectroscopy. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli...

  19. CMOS Integrated Carbon Nanotube Sensor

    International Nuclear Information System (INIS)

    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  20. Preparation of very long and open aligned carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    潘正伟; 常保和; 孙连峰; 钱露茜; 刘祖琴; 唐东升; 王刚; 解思深

    2000-01-01

    Very long and open aligned carbon nanotubes that reach about 2 mm long, an order of magnitude longer than previously reached, have been prepared by chemical vapor deposition over silica dioxide substrates on the surface, where iron/silica nano-composite particles are evenly positioned. The nanotubes are naturally opened at the bottom ends. The growth mechanism of the very long and open-ended nanotubes is also discussed.

  1. Synthesis of Carbon Nanotubes by MWPCVD at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 王传新; 马志彬; 满卫东

    2002-01-01

    Growth of carbon nanotubes (CNTs) at low temperature is very important to the applications of nanotubes. In this paper, under the catalytic effect of cobalt nanoparticles supported by SiO2, CNTs were synthesized by microwave plasma chemical vapor deposition (MWPCVD)below 500℃. It demonstrates that MWPCVD can be a very efficient process for the synthesis of CNTs at low temperature.

  2. Modified carbon nanotubes and methods of forming carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  3. Growth of Carbon Nanotubes over Ni Nano-particles Prepared in Situ by Reduction of La2NiO4 Oxides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel catalyst precursor, La2NiO4, was investigated to synthesize carbon nanotubes, obtained from catalytic disproportionation of CO. The morphology of carbon nanotubes has been examined by TEM (transmission electron micrograph) and SEM (scaning electron micrograph). It was observed that the Ni nano-particle size formed at different reducing temperatures was a key factor to the yield and diameter of carbon nanotubes.

  4. Synthesis of carbon nanotubes with and without catalyst particles

    Directory of Open Access Journals (Sweden)

    Cuniberti Gianaurelio

    2011-01-01

    Full Text Available Abstract The initial development of carbon nanotube synthesis revolved heavily around the use of 3d valence transition metals such as Fe, Ni, and Co. More recently, noble metals (e.g. Au and poor metals (e.g. In, Pb have been shown to also yield carbon nanotubes. In addition, various ceramics and semiconductors can serve as catalytic particles suitable for tube formation and in some cases hybrid metal/metal oxide systems are possible. All-carbon systems for carbon nanotube growth without any catalytic particles have also been demonstrated. These different growth systems are briefly examined in this article and serve to highlight the breadth of avenues available for carbon nanotube synthesis.

  5. Fermentation based carbon nanotube multifunctional bionic composites

    OpenAIRE

    Luca Valentini; Silvia Bittolo Bon; Stefano Signetti; Manoj Tripathi; Erica Iacob; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extr...

  6. Fermentation based carbon nanotube bionic functional composites

    OpenAIRE

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique mechanical and physical properties that are not produced by abiotic processes. Based on grape must and bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at r...

  7. CARBON NANOTUBES AND PHARMACEUTICAL APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Ram Pavani

    2011-07-01

    Full Text Available Carbon nanotubes (CNTs are often described as a graphene sheet rolled up into the shape of a cylinder. These have fascinated scientists with their extraordinary properties. These compounds have become increasingly popular in various fields simply because of their small size and amazing optical, electric and magnetic properties when used alone or with additions of metals. Carbon nanotubes have potential therapeutic applications in the field of drug delivery, diagnostics, and biosensing. Functionalized carbon nanotubes can also act as vaccine delivery systems.Carbon nanotubes (CNTs are considered to be one of the innovative resources in nanotechnology with possible use in wide range of biomedical applications viz. cancer treatment, bioengineering, cardiac autonomic regulation, platelet activation and tissue regeneration. The effect of CNTs on cells and tissues are extremely important for their use in various complex biological systems. With the increasing interest shown by the nanotechnology research community in this field, it is expected that plenty of applications of CNTs will be explored in future.

  8. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Laird, E.A.; Kuemmeth, F.; Steele, G.A.; Grove-Rasmussen, K.; Nygard, J.; Flensberg, K.; Kouwenhoven, L.P.

    2015-01-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This revie

  9. Atomic scale simulation of carbon nanotube nucleation from hydrocarbon precursors.

    Science.gov (United States)

    Khalilov, Umedjon; Bogaerts, Annemie; Neyts, Erik C

    2015-12-22

    Atomic scale simulations of the nucleation and growth of carbon nanotubes is essential for understanding their growth mechanism. In spite of over twenty years of simulation efforts in this area, limited progress has so far been made on addressing the role of the hydrocarbon growth precursor. Here we report on atomic scale simulations of cap nucleation of single-walled carbon nanotubes from hydrocarbon precursors. The presented mechanism emphasizes the important role of hydrogen in the nucleation process, and is discussed in relation to previously presented mechanisms. In particular, the role of hydrogen in the appearance of unstable carbon structures during in situ experimental observations as well as the initial stage of multi-walled carbon nanotube growth is discussed. The results are in good agreement with available experimental and quantum-mechanical results, and provide a basic understanding of the incubation and nucleation stages of hydrocarbon-based CNT growth at the atomic level.

  10. Attachment of Gold Nanoparticles to Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng MA; Ning LUN; Shu Lin WEN

    2005-01-01

    Carbon nanotubes were initially chemically modified with an H2SO4-HNO3 treatment,and subsequently activated with Pd-Sn catalytic nuclei via a one-step activation approach. These activated nanotubes were used as precursors for obtaining gold nanoparticles-attached nanotubes via simple electroless plating. This approach provides an efficient method for attachment of metal nanostructures to carbon nanotubes. Such novel hybrid nanostructures are attractive for many applications.

  11. From carbon nanotubes to carbon atomic chains

    Science.gov (United States)

    Casillas García, Gilberto; Zhang, Weijia; José-Yacamán, Miguel

    2010-10-01

    Carbyne is a linear allotrope of carbon. It is formed by a linear arrangement of carbon atoms with sp-hybridization. We present a reliable and reproducible experiment to obtain these carbon atomic chains using few-layer-graphene (FLG) sheets and a HRTEM. First the FLG sheets were synthesized from worm-like exfoliated graphite and then drop-casted on a lacey-carbon copper grid. Once in the TEM, two holes are opened near each other in a FLG sheet by focusing the electron beam into a small spot. Due to the radiation, the carbon atoms rearrange themselves between the two holes and form carbon fibers. The beam is concentrated on the carbon fibers in order excite the atoms and induce a tension until multi wall carbon nanotube (MWCNT) is formed. As the radiation continues the MWCNT breaks down until there is only a single wall carbon nanotube (SWCNT). Then, when the SWCNT breaks, an atomic carbon chain is formed, lasts for several seconds under the radiation and finally breaks. This demonstrates the stability of this carbon structure.

  12. Bloch oscillations in carbon nanotubes.

    Science.gov (United States)

    Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.

  13. Dispersion fraction enhances cellular growth of carbon nanotube and aluminum oxide reinforced ultrahigh molecular weight polyethylene biocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anup Kumar; Balani, Kantesh, E-mail: kbalani@iitk.ac.in

    2015-01-01

    Ultrahigh molecular weight polyethylene (UHMWPE) is widely used as bone-replacement material for articulating surfaces due to its excellent wear resistance and low coefficient of friction. But, the wear debris, generated during abrasion between mating surfaces, leads to aseptic loosening of implants. Thus, various reinforcing agents are generally utilized, which may alter the surface and biological properties of UHMWPE. In the current work, the cellular response of compression molded UHMWPE upon reinforcement of bioactive multiwalled carbon nanotubes (MWCNTs) and bioinert aluminum oxide (Al{sub 2}O{sub 3}) is investigated. The phase retention and stability were observed using X-ray diffraction, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The reinforcement of MWCNTs and Al{sub 2}O{sub 3} has shown to alter the wettability (from contact angle of ∼ 88° ± 2° to ∼ 118° ± 4°) and surface energy (from ∼ 23.20 to ∼ 17.75 mN/m) of composites with respect to UHMWPE, without eliciting any adverse effect on cytocompatibility for the L929 mouse fibroblast cell line. Interestingly, the cellular growth of the L929 mouse fibroblast cell line is observed to be dominated by the dispersion fraction of surface free energy (SFE). After 48 h of incubation period, a decrease in metabolic activity of MWCNT–Al{sub 2}O{sub 3} reinforced composites is attributed to apatite formation that reduces the dispersion fraction of surface energy. The mineralized apatite during incubation was confirmed and quantified by energy dispersive spectroscopy and X-ray diffraction respectively. Thus, the dispersion fraction of surface free energy can be engineered to play an important role in achieving enhanced metabolic activity of the MWCNT–Al{sub 2}O{sub 3} reinforced UHMWPE biopolymer composites. - Highlights: • The cellular response of UHMWPE upon MWCNT and Al{sub 2}O{sub 3} reinforcement is highlighted. • Wettability decreases with Al{sub 2}O{sub 3} and

  14. Carbon nanotube materials from hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F. [National Renewable Energy Laboratory, Golden, CO (United States)

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  15. Diffusion through Carbon Nanotube Semipermeable membranes

    Energy Technology Data Exchange (ETDEWEB)

    Bakajin, O

    2006-02-13

    The goal of this project is to measure transport through CNTs and study effects of confinement at molecular scale. This work is motivated by several simulation papers in high profile journals that predict significantly higher transport rates of gases and liquids through carbon nanotubes as compared with similarly-sized nanomaterials (e.g. zeolites). The predictions are based on the effects of confinement, atomically smooth pore walls and high pore density. Our work will provide the first measurements that would compare to and hopefully validate the simulations. Gas flux is predicted to be >1000X greater for SWNTs versus zeolitesi. A high flux of 6-30 H2O/NT/ns {approx} 8-40 L/min for a 1cm{sup 2} membrane is also predicted. Neutron diffraction measurements indicate existence of a 1D water chain within a cylindrical ice sheet inside carbon nanotubes, which is consistent with the predictions of the simulation. The enabling experimental platform that we are developing is a semipermeable membrane made out of vertically aligned carbon nanotubes with gaps between nanotubes filled so that the transport occurs through the nanotubes. The major challenges of this project included: (1) Growth of CNTs in the suitable vertically aligned configuration, especially the single wall carbon nanotubes; (2) Development of a process for void-free filling gaps between CNTs; and (3) Design of the experiments that will probe the small amounts of analyte that go through. Knowledge of the behavior of water upon nanometer-scale confinement is key to understanding many biological processes. For example, the protein folding process is believed to involve water confined in a hydrophobic environment. In transmembrane proteins such as aquaporins, water transport occurs under similar conditions. And in fields as far removed as oil recovery and catalysis, an understanding of the nanoscale molecular transport occurring within the nanomaterials used (e.g. zeolites) is the key to process optimization

  16. Production of single-walled carbon nanotube grids

    Science.gov (United States)

    Hauge, Robert H; Xu, Ya-Qiong; Pheasant, Sean

    2013-12-03

    A method of forming a nanotube grid includes placing a plurality of catalyst nanoparticles on a grid framework, contacting the catalyst nanoparticles with a gas mixture that includes hydrogen and a carbon source in a reaction chamber, forming an activated gas from the gas mixture, heating the grid framework and activated gas, and controlling a growth time to generate a single-wall carbon nanotube array radially about the grid framework. A filter membrane may be produced by this method.

  17. Febrication of Carbon-Nanotube-Forest Based Bolometer

    OpenAIRE

    Wood, Brian; Dyer, J. S.; Thurgood, V. A.; Shen, T. -C.

    2014-01-01

    Due to the nearly-vertical alignment and the band structure of graphite, carbon nanotube forests could have near-unity emissivity which make them ideal candidates as the absorbers for radiometric devices. However, forest height, carbon nanotube density, and the presence of surface defects will affect the total reflectance and transmittance. With optimized growth conditions, a total reflectance of 0.003 and a transmittance of 0.001 has been achieved in the 2 µm - 16 µm spectral region. Fabrica...

  18. Roping and wrapping carbon nanotubes

    Science.gov (United States)

    Ausman, Kevin D.; O'Connell, Michael J.; Boul, Peter; Ericson, Lars M.; Casavant, Michael J.; Walters, Deron A.; Huffman, Chad; Saini, Rajesh; Wang, Yuhuang; Haroz, Erik; Billups, Edward W.; Smalley, Richard E.

    2001-11-01

    Single-walled carbon nanotubes can be dispersed into solvents by ultrasonication to the point that primarily individual tubes, cut to a few hundred nanometers in length, are present. However, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this "roping" phenomenon, akin to aggregation or crystallization, will be discussed. We have developed methods for generating "super-ropes" more than twenty times the diameter of those formed by filtration, involving the extraction of nanotube material from an oleum dispersion. Nanotubes have been solubilized in water, largely individually, by non-covalently wrapping them with linear polymers. The general thermodynamic drive for this wrapping involves the polymer disrupting both the hydrophobic interface with water and the smooth tube-tube interaction in aggregates. The nanotubes can be recovered from their polymeric wrapping by changing their solvent system. This solubilization process opens the door to solution chemistry on pristine nanotubes, as well as their introduction into biologically relevant systems.

  19. Nanotubes in Nanoelectronics: Transport, Growth and Modeling

    Science.gov (United States)

    Anantram, M.; Delzeit, Lance; Cassell, Alan; Han, Jie; Meyyappan, M.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) baud nanotechnology appears to be promising for future Theoretical analysis and results for the ballistic current carrying capacity of nanotube wires am presented. Aspects of metal-nanotube coupling are examined. Results am also presented for chemical vapor deposition of CNT from hydrocarbon feedstock.

  20. Carbon nanotube diameter selection by pretreatment of metal catalysts on surfaces

    Science.gov (United States)

    Hauge, Robert H.; Xu, Ya-Qiong; Shan, Hongwei; Nicholas, Nolan Walker; Kim, Myung Jong; Schmidt, Howard K.; Kittrell, W. Carter

    2012-02-28

    A new and useful nanotube growth substrate conditioning processes is herein disclosed that allows the growth of vertical arrays of carbon nanotubes where the average diameter of the nanotubes can be selected and/or controlled as compared to the prior art.

  1. Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes

    Science.gov (United States)

    Ramasubramaniam, Rajagopal; Chen, Jian; Gupta, Rishi

    2003-03-01

    Individual carbon nanotubes show superior electrical, mechanical and thermal properties [1]. Composite materials using carbon nanotubes as fillers are predicted to show similar superior properties. However, realization of such composites has been plagued by poor dispersion of carbon nanotubes in solvents and in polymer matrices. We have developed a method to homogenously disperse carbon nanotubes in polymer matrices using functionalized nanotubes [2]. Thin films of functionalized single walled nanotubes (SWNT) - polystyrene composites and functionalized SWNT - polycarbonate composites were prepared using solution evaporation and spin coating. Both of the composites show several orders of magnitude increase in conductivity for less than 1 wt thresholds of the composites are less than 0.2 wt nanotubes. We attribute the enhanced conduction to the superior dispersion of the functionalized nanotubes in the polymer matrix and to the reduced nanotube waviness resulting from the rigid backbone of the conjugated polymer. References: [1]. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science v297, p787 (2002); [2]. J. Chen, H. Liu, W. A. Weimer, M. D. Halls, D. H. Waldeck and G. C. Walker, J. Am. Chem. Soc. v124, p9034 (2002).

  2. Carbon Nanotubes Filled with Ferromagnetic Materials

    Directory of Open Access Journals (Sweden)

    Albrecht Leonhardt

    2010-08-01

    Full Text Available Carbon nanotubes (CNT filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology.

  3. Different Technical Applications of Carbon Nanotubes

    OpenAIRE

    Abdalla, S; Al-Marzouki, F.; Ahmed A. Al-Ghamdi; Abdel-Daiem, A.

    2015-01-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc....

  4. Carbon Nanotubes and Related Structures

    Directory of Open Access Journals (Sweden)

    Kingsuk Mukhopadhyay

    2008-07-01

    Full Text Available Carbon nanotubes have attracted the fancy of many scientists world wide. The small dimensions,strength, and the remarkable physical properties of these structures make them a unique material with a whole range of promising applications. In this review, the structural aspects, the advantages and disadvantages of different for their procedures synthesis, the qualitative and quantitative estimation of carbon nanotubes by different analytical techniques, the present status on their applications as well as the current challenges faced in the application field, national, in particular DRDO, DMSRDE status, and interest in this field, have been discussed.Defence Science Journal, 2008, 58(4, pp.437-450, DOI:http://dx.doi.org/10.14429/dsj.58.1666

  5. Ballistic Fracturing of Carbon Nanotubes.

    Science.gov (United States)

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome.

  6. Photoluminescence Study of Carbon Nanotubes

    OpenAIRE

    Han, H. X.; Li, G. H.; Ge, W. K.; Wang, Z. P.; Xu, Z. Y.; Xie, S. S.; Chang, B H; Sun, L. F.; Wang, B S; G. Xu; Su, Z.B.

    2000-01-01

    ultiwalled carbon nanotubes, prepared by both electric arc discharge and chemical vapor deposition methods, show a strong visible light emission in photoluminescence experiments. All the samples employed in the experiments exhibit nearly same super-linear intensity dependence of the emission bands on the excitation intensity, and negligible temperature dependence of the central position and the line shapes of the emission bands. Based upon theoretical analysis of the electronic band structure...

  7. Photonics based on carbon nanotubes

    OpenAIRE

    Gu, Qingyuan; Gicquel-Guézo, Maud; Loualiche, Slimane; Pouliquen, Julie Le; Batte, Thomas; Folliot, Hervé; Dehaese, Olivier; Grillot, Frederic; Battie, Yann; Loiseau, Annick; Liang, Baolai; Huffaker, Diana

    2013-01-01

    Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the effi...

  8. OPPORTUNITIES OF BIOMEDICAL USE OF CARBON NANOTUBES

    Directory of Open Access Journals (Sweden)

    I. V. Mitrofanova

    2015-12-01

    Full Text Available Nanomaterials  –  materials,  whouse  structure  elements  has  proportions  doesn’t  exceed  100  nm.  In superdispersed state matter acquire new properties. In the last decade, carbon nanotubes become the most popular nanomaterials, that cause attention of representatives of various scientific field. The сarbon nanotubes offer new opportunities for biological and medical applications: imaging at the molecular, cellular and tissue levels, biosensors and electrodes based on carbon nanotubes, target delivery of various substances, radiation and photothermal therapy. The most promising of carbon nanotubes in the context of biomedical applications is their ability to penetrate the various tissues of the body and carry large doses of agents, providing diagnostic and therapeutic effects. Functionalized nanotubes are biodegradable. Other current direction of using carbon nanotubes in medicine and biology is to visualize objects on the molecular, cellular and tissue level. Associated with carbon nanotubes contrasting substances improve the visualization of cells and tissues, which can detected new patterns of development of the pathological process. Due to the vagueness of the question of biocompatibility and cytotoxicity of carbon nanotubes possibility of their practical application is hampered. Before the introduction of carbon nanotubes into practical health care is necessary to provide all the possible consequences of using nanotubes. High rates of properties and development of new nanostructures based on carbon nanotubes in the near future will lead to new advances related to the application and development of new parameters that will determine their properties and effects. In these review attention is paid to the structure, physico-chemical properties of nanotubes, their functionalization, pharmacokinetics and pharmacodynamics and all aspects of using of carbon nanotubes.

  9. LDRD final report on carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, P.A.; Rand, P.B.

    1997-04-01

    Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

  10. Engineering carbon nanotubes and nanotube circuits using electrical breakdown.

    Science.gov (United States)

    Collins, P G; Arnold, M S; Avouris, P

    2001-04-27

    Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or "ropes" of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs.

  11. Real-Time Observation of Cell and Carbon Nanotube Interactions

    Science.gov (United States)

    Chen, Michelle; Broman, Melanie; Mathews, Claire; McPherson, Eric

    2014-03-01

    Carbon nanotubes have been widely researched for disease diagnosis and drug delivery applications. However, its impact on biological systems is yet to be sufficiently understood. We studied optical imaging of Chinese hamster ovarian (CHO) cells exposed to various carbon nanotubes concentrations at various time points. The cell stress due to carbon nanotubes exposure is accessed via morphological changes of the CHO cells. Data showed that cell death increases with increasing carbon nanotube concentration and time exposure. To continuously view such changes of any one individual cell, we constructed an optically transparent miniaturized incubator that fits on a microscope stage. This specific incubator is able to maintain desirable temperature, humidity, and CO2 concentration to allow proper cell growth. Such incubator can be used to track real-time interactions of any cells and nanomaterials for future data collection.

  12. Structure of single-wall carbon nanotubes: a graphene helix.

    Science.gov (United States)

    Lee, Jae-Kap; Lee, Sohyung; Kim, Jin-Gyu; Min, Bong-Ki; Kim, Yong-Il; Lee, Kyung-Il; An, Kay Hyeok; John, Phillip

    2014-08-27

    Evidence is presented in this paper that certain single-wall carbon nanotubes are not seamless tubes, but rather adopt a graphene helix resulting from the spiral growth of a nano-graphene ribbon. The residual traces of the helices are confirmed by high-resolution transmission electron microscopy and atomic force microscopy. The analysis also shows that the tubular graphene material may exhibit a unique armchair structure and the chirality is not a necessary condition for the growth of carbon nanotubes. The description of the structure of the helical carbon nanomaterials is generalized using the plane indices of hexagonal space groups instead of using chiral vectors. It is also proposed that the growth model, via a graphene helix, results in a ubiquitous structure of single-wall carbon nanotubes. PMID:24838196

  13. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane....... The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an electric field, thus enabling nanotube integration in microsystems. Dielectrophoresis offers also...... the potential of distinguishing between nanotubes of different electrical properties, which is very important for the optimisation of the properties of the carbon nanotube sensors. Various cantilever and planar structures were designed, fabricated and tested both with multi-walled and single-walled carbon...

  14. Laser patterning of vertically grown carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Won Seok [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2012-12-15

    The selective patterning of a carbon nanotube (CNT) forest on a Si substrate has been performed using a femtosecond laser. The high shock wave generated by the femtosecond laser effectively removed the CNTs without damage to the Si substrate. This process has many advantages because it is performed without chemicals and can be easily applied to large area patterning. The CNTs grown by plasma enhanced chemical vapor deposition (PECVD) have a catalyst cap at the end of the nanotube owing to the tip growth mode mechanism. For the application of an electron emission and biosensor probe, the catalyst cap is usually removed chemically, which damages the surface of the CNT wall. Precise control of the femtosecond laser power and focal position could solve this problem. Furthermore, selective CNT cutting using a femtosecond laser is also possible without any phase change in the CNTs, which is usually observed in the focused ion beam irradiation of CNTs.

  15. Mapping the transition from catalyst-pool to bamboo-like growth-mechanism in vertically-aligned free-standing films of carbon nanotubes filled with Fe3C: The key role of water

    Science.gov (United States)

    Boi, Filippo S.; Wang, Shanling; He, Yi

    2016-08-01

    The control of carbon nanotube growth has challenged researchers for more than a decade due to the complex parameters-control necessary in the commonly used CVD approaches. Here we show that a direct transition from the catalyst-pool growth mechanism characterized by graphene-caps in the direction of growth to a bamboo-shaped mechanism characterized by the repetition of periodic elongated graphitic compartments is present when controlled quantities of water are added to ferrocene/dichlorobenzene. Our results suggest that water-addition allows enhancing the level of stress accumulated under the graphitic nanotubes-cap.

  16. Study of Carbon Nanotube-Substrate Interaction

    Directory of Open Access Journals (Sweden)

    Jaqueline S. Soares

    2012-01-01

    Full Text Available Environmental effects are very important in nanoscience and nanotechnology. This work reviews the importance of the substrate in single-wall carbon nanotube properties. Contact with a substrate can modify the nanotube properties, and such interactions have been broadly studied as either a negative aspect or a solution for developing carbon nanotube-based nanotechnologies. This paper discusses both theoretical and experimental studies where the interaction between the carbon nanotubes and the substrate affects the structural, electronic, and vibrational properties of the tubes.

  17. A Tunable Carbon Nanotube Oscillator

    Science.gov (United States)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  18. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  19. Synthesis of carbon nanotubes by catalytic pyrolysis method with Feitknecht compound as precursor of NiZnAl catalyst

    Institute of Scientific and Technical Information of China (English)

    Yan Xiaoqi; Liu Quanrun; Zhang Songlin; Zhang Kun; Chen Jiuling; Li Yongdan

    2004-01-01

    Carbon nanotubes are synthesized by catalytic pyrolysis method with a kind of new type catalyst--nickel-zinc-alumina catalyst prepared from Feitknecht compound. Tubular carbon nanotubes, bamboo-shaped carbon naotubes, herringbone carbon nanotubues and branched carbon nanotubes are all found formed at moderate temperature. It is important for the formation of quasi-liquid state of the metal nanoparticles at the tip of carbon naotubes during the growth of carbon nanotubes to lead to different kinds of carbon nanotubes. It is likely that the addition of zinc make the activity of nickel catalyst after calcinations and reduction changed strangely.

  20. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  1. Functional Materials based on Carbon Nanotubes

    OpenAIRE

    Jung, Adrian Thomas

    2007-01-01

    Carbon nanotubes, no matter if they are single-walled or multi-walled, are an integral component in the vastly growing field of nanotechnology. Since their discovery by TEM and the invention of numerous large-scale production techniques, nanotubes are close to making their way into industrial products. Although many properties and modification processes are still under intensive research, the first real-market applications for carbon nanotubes have already been presented. However, if function...

  2. Growth of aligned single-walled carbon nanotubes under ac electric fields through floating catalyst chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Dou Xin-Yuan; Luo Shu-Dong; Zhang Zeng-Xing; Liu Dong-Fang; Wang Jian-Xiong; Gao Yan; Zhou Wei-Ya; Wang Gang; Zhou Zhen-Ping; Tan Ping-Heng; Zhou Jian-Jun; Song Li; Sun Lian-Feng; Jiang Peng; Liu Li-Feng; Zhao Xiao-Wei

    2005-01-01

    Through floating catalyst chemical vapour deposition(CVD) method, well-aligned isolated single-walled carbon nanotubes (SWCNTs) and their bundles were deposited on the metal electrodes patterned on the SiO2/Si surface under ac electric fields at relatively low temperature(280℃). It was indicated that SWCNTs were effectively aligned under ac electric fields after they had just grown in the furnace. The time for a SWCNT to be aligned in the electric field and the effect of gas flow were estimated. Polarized Raman scattering was performed to characterize the aligned structure of SWCNTs. This method would be very useful for the controlled fabrication and preparation of SWCNTs in practical applications.

  3. Optimization of growth temperature of multi-walled carbon nanotubes synthesized by spray pyrolysis method and application for arsenic removal

    Directory of Open Access Journals (Sweden)

    S. Mageswari

    2014-12-01

    Full Text Available Multi-walled carbon nanotubes have been synthesized at different temperatures ranging from 550 °C to 750 °C on silica supported Fe-Co catalyst by spray pyrolysis method using Citrus limonum oil under nitrogen atmosphere. The as-grown MWNTs were characterized by scanning electron microscope (SEM, high resolution transmission electron microscope (HRTEM, X-ray diffraction analysis (XRD and Raman spectral studies. The HRTEM and Raman spectroscopic studies confirmed the evolution of MWNTs with the outer diameter between 25 and 38 nm. The possibility of use of as-grown MWNTs as an adsorbent for removal of As (V ions from drinking water was studied. Adsorption isotherm data were interpreted by the Langmuir and Freundlich equations. Kinetic data were studied using Elovich, pseudo-first order and pseudo-second order equations in order to elucidate the reaction mechanism.

  4. Growth of single-crystal α-MnO2 nanorods on multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Single-crystal α-MnO2 nanorods were grown on multi-walled carbon nanotubes (MWNTs) in H2SO4 aqueous solution. The morphology and microstructure of the composites were examined by transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), X-ray diffractometry and energy dispersive spectroscopy (EDS). The results show that α-MnO2 single-crystal nanorods with a mean diameter of 15 nm were densely grown on the surface of MWNTs. Those MWNTs/MnO2 composites were used as an electrode material for supercapacitors, and it was found that the supercapacitor performance using MWNTs/MnO2 composites was improved largely compared to that using pure MWNTs and α-MnO2 nanorod mechanically mixed with MWNTs

  5. Glucose oxidase immobilization onto carbon nanotube networking

    CERN Document Server

    Karachevtsev, V A; Zarudnev, E S; Karachevtsev, M V; Leontiev, V S; Linnik, A S; Lytvyn, O S; Plokhotnichenko, A M; Stepanian, S G

    2012-01-01

    When elaborating the biosensor based on single-walled carbon nanotubes (SWNTs), it is necessary to solve such an important problem as the immobilization of a target biomolecule on the nanotube surface. In this work, the enzyme (glucose oxidase (GOX)) was immobilized on the surface of a nanotube network, which was created by the deposition of nanotubes from their solution in 1,2-dichlorobenzene by the spray method. 1-Pyrenebutanoic acid succinimide ester (PSE) was used to form the molecular interface, the bifunctional molecule of which provides the covalent binding with the enzyme shell, and its other part (pyrene) is adsorbed onto the nanotube surface. First, the usage of such a molecular interface leaves out the direct adsorption of the enzyme (in this case, its activity decreases) onto the nanotube surface, and, second, it ensures the enzyme localization near the nanotube. The comparison of the resonance Raman (RR) spectrum of pristine nanotubes with their spectrum in the PSE environment evidences the creat...

  6. Polymer Self-assembly on Carbon Nanotubes

    Science.gov (United States)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  7. Photoluminescence from single walled carbon nanotubes: a comparison between suspended and micelle-encapsulated nanotubes

    OpenAIRE

    Lefebvre, J.; Fraser, J. M.; Homma, Y; Finnie, P.

    2003-01-01

    Single walled carbon nanotubes (SWNTs) are luminescent. Up to now, two preparation methods, both of which isolate individual SWNTs, have enabled the detection of nanotube bandgap photoluminescence (PL): encapsulation of individual SWNTs into surfactant micelles, and direct growth of individual SWNTs suspended in air between pillars. This paper compares the PL obtained from suspended SWNTs to published PL data obtained from encapsulated SWNTs. We find that emission peaks are blue-shifted by 28...

  8. Suspended carbon nanotubes coupled to superconducting circuits

    NARCIS (Netherlands)

    Schneider, B.H.

    2014-01-01

    Carbon nanotubes are unique candidates to study quantum mechanical properties of a nanomechanical resonator. However to access this quantum regime, present detectors are not yet sensitive enough. In this thesis we couple a carbon nanotube CNT mechanical resonator to a superconducting circuit which i

  9. Catalytic activity of Fe, Co and Fe-Co-MCM-41 for the growth of carbon nanotubes by chemical vapour deposition method

    International Nuclear Information System (INIS)

    Iron, cobalt and a mixture of iron and cobalt incorporated mesoporous MCM-41 molecular sieves were synthesised by hydrothermal method and used to investigate the rules governing their nanotube producing activity. The catalysts were characterised by XRD and N2 sorption studies. The effect of the catalysts has been investigated for the production of carbon nanotubes at an optimised temperature 750 deg. C with flow rate of N2 and C2H2 is 140 and 60 ml/min, respectively for a reaction time 10 min. Fe-Co-MCM-41 catalyst was selective for carbon nanotubes with low amount of amorphous carbon with increase in single-walled carbon nanotubes (SWNTs) yield at 750 deg. C. Formation of nanotubes was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Transmission electron microscope and Raman spectrum was used to follow the quality and nature of carbon nanotubes formed and the graphitic layers and disordered band, which shows the clear evidence for the formation of SWNTs, respectively. The result propose that the diameter of the nanotubes in the range of 0.78-1.35 nm. Using our optimised conditions for this system, Fe-Co-MCM-41 showed the best results for selective SWNTs with high yield when compared with Fe-MCM-41 and Co-MCM-41

  10. Frontiers of graphene and carbon nanotubes devices and applications

    CERN Document Server

    2015-01-01

    This book focuses on carbon nanotubes and graphene as representatives of nano-carbon materials, and describes the growth of new technology and applications of new devices. As new devices and as new materials, nano-carbon materials are expected to be world pioneers that could not have been realized with conventional semiconductor materials, and as those that extend the limits of conventional semiconductor performance. This book introduces the latest achievements of nano-carbon devices, processes, and technology growth. It is anticipated that these studies will also be pioneers in the development of future research of nano-carbon devices and materials. This book consists of 18 chapters. Chapters 1 to 8 describe new device applications and new growth methods of graphene, and Chapters 9 to 18, those of carbon nanotubes. It is expected that by increasing the advantages and overcoming the weak points of nanocarbon materials, a new world that cannot be achieved with conventional materials will be greatly expanded. W...

  11. Light Emission in Silicon from Carbon Nanotubes

    CERN Document Server

    Gaufrès, Etienne; Noury, Adrien; Roux, Xavier Le; Rasigade, Gilles; Beck, Alexandre; Vivien, Laurent

    2015-01-01

    The use of optics in microelectronic circuits to overcome the limitation of metallic interconnects is more and more considered as a viable solution. Among future silicon compatible materials, carbon nanotubes are promising candidates thanks to their ability to emit, modulate and detect light in the wavelength range of silicon transparency. We report the first integration of carbon nanotubes with silicon waveguides, successfully coupling their emission and absorption properties. A complete study of this coupling between carbon nanotubes and silicon waveguides was carried out, which led to the demonstration of the temperature-independent emission from carbon nanotubes in silicon at a wavelength of 1.3 {\\mu}m. This represents the first milestone in the development of photonics based on carbon nanotubes on silicon.

  12. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2.xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2.xH2O in the composite electrodes reaches 75%. In addition, supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  13. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    马仁志; 魏秉庆; 徐才录; 梁吉; 吴德海

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2 ·xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2· xH2O in the composite electrodes reaches 75% . In addition , supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  14. Computational Aspects of Carbon and Boron Nanotubes

    Directory of Open Access Journals (Sweden)

    Paul Manuel

    2010-11-01

    Full Text Available Carbon hexagonal nanotubes, boron triangular nanotubes and boron a-nanotubes are a few popular nano structures. Computational researchers look at these structures as graphs where each atom is a node and an atomic bond is an edge. While researchers are discussing the differences among the three nanotubes, we identify the topological and structural similarities among them. We show that the three nanotubes have the same maximum independent set and their matching ratios are independent of the number of columns. In addition, we illustrate that they also have similar underlying broadcasting spanning tree and identical communication behavior.

  15. Exciton resonances quench the photoluminescence of zigzag carbon nanotubes

    OpenAIRE

    Reich, Stephanie; Thomsen, Christian; Robertson, John

    2005-01-01

    We show that the photoluminescence intensity of single-walled carbon nanotubes is much stronger in tubes with large chiral angles - armchair tubes - because exciton resonances make the luminescence of zigzag tubes intrinsically weak. This exciton-exciton resonance depends on the electronic structure of the tubes and is found more often in nanotubes of the +1 family. Armchair tubes do not necessarily grow preferentially with present growth techniques; they just have stronger luminescence. Our ...

  16. Growing carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Yoshinori Ando

    2004-10-01

    Full Text Available The discovery of ‘fullerenes’ added a new dimension to the knowledge of carbon science1; and the subsequent discovery of ‘carbon nanotubes’ (CNTs, the elongated fullerene added a new dimension to the knowledge of technology2;. Today, ‘nanotechnology’ is a hot topic attracting scientists, industrialists, journalists, governments, and even the general public. Nanotechnology is the creation of functional materials, devices, and systems through control of matter on the nanometer scale and the exploitation of novel phenomena and properties of matter (physical, chemical, biological, electrical, etc. at that length scale. CNTs are supposed to be a key component of nanotechnology. Almost every week a new potential application of CNTs is identified, stimulating scientists to peep into this tiny tube with ever increasing curiosity.

  17. Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes

    Indian Academy of Sciences (India)

    F L Deepak; A Govindaraj; C N R Rao

    2006-01-01

    Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Yjunction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallicthiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon nanotubes with Y-junctions. Pyrolysis of organometallic-hydrocarbon mixtures, in the absence of water vapour, only gives nanotubes with T- and Y-junctions.

  18. Carbon Nanotube Microarrays Grown on Nanoflake Substrates

    Science.gov (United States)

    Schmidt, Howard K.; Hauge, Robert H.; Pint, Cary; Pheasant, Sean

    2013-01-01

    This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats. The alignment of the nanotubes is similar to that achieved in vertically aligned nanotubes, which are called "carpets. " Because these flakes are grown in a state where they are airborne in a reactor, these flakes, after growing SWNTs, are termed "flying carpets. " These flakes are created in a roll-to-roll evaporator system, where three subsequent evaporations are performed on a 100-ft (approx. =30-m) roll of Mylar. The first layer is composed of a water-soluble "release layer, " which can be a material such as NaCl. After depositing NaCl, the second layer involves 40 nm of supporting layer material . either Al2O3 or MgO. The thickness of the layer can be tuned to synthesize flakes that are larger or smaller than those obtained with a 40-nm deposition. Finally, the third layer consists of a thin Fe catalyst layer with a thickness of 0.5 nm. The thickness of this layer ultimately determines the diameter of SWNT growth, and a layer that is too thick will result in the growth of multiwalled carbon nanotubes instead of single-wall nanotubes. However, between a thickness of 0.5 nm to 1 nm, single-walled carbon nanotubes are known to be the primary constituent. After this three-layer deposition process, the Mylar is rolled through a bath of water, which allows catalyst-coated flakes to detach from the Mylar. The flakes are then collected and dried. The method described here for making such flakes is analogous to that which is used to make birefringent ink that is

  19. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  20. Purification of carbon nanotube by wet oxidation; Shisshiki sanka ni yoru carbon nanotube no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, K.; Takarada, T. [Gunma University, Gunma (Japan)

    1997-07-10

    In order to efficiently recover carbon nanotubes, the purification method by wet oxidation with orthoperiodic acid and perchloric acid is investigated. The reactivity of the carbonaceous material toward the acids depends on the type of carbon. Carbon nanotubes are selectively recovered under the mild oxidation conditions. The degree of purification depends on the concentration of orthoperiodic acid. It is suggested that wet oxidation is an effective method for purification of carbon nanotubes. 17 refs., 6 figs.

  1. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    Science.gov (United States)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  2. A one-step single source route to carbon nanotubes

    Indian Academy of Sciences (India)

    Tao Cheng; Zhiyong Fang; Guifu Zou; Qixiu Hu; Biao Hu; Xiaozhi Yang; Youjin Zhang

    2006-12-01

    Carbon nanotubes (CNTs) have been synthesized via directly pyrolyzing ferrocene in the autoclave. The nanotubes with several micrometers in length have outer and inner diameters in the range of 40–100 nm and 20–40 nm, respectively. An yield of ∼70% of CNTs can be obtained without any accessorial solvents and catalysts. Experimental results showed that a temperature higher than 600°C in conjunction with proper pressure was favourable for achievement of the nanotubes. The growth mechanism of CNTs was also discussed.

  3. Mechanisms of Carbon Nanotube Production by Laser Ablation Process

    Science.gov (United States)

    Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

    2000-01-01

    We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

  4. Catalysts for Efficient Production of Carbon Nanotubes

    Science.gov (United States)

    Sun, Ted X.; Dong, Yi

    2009-01-01

    Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

  5. Functionalized carbon nanotubes: biomedical applications

    Directory of Open Access Journals (Sweden)

    Vardharajula S

    2012-10-01

    Full Text Available Sandhya Vardharajula,1 Sk Z Ali,2 Pooja M Tiwari,1 Erdal Eroğlu,1 Komal Vig,1 Vida A Dennis,1 Shree R Singh11Center for NanoBiotechnology and Life Sciences Research, Alabama State University, Montgomery, AL, USA; 2Department of Microbiology, Osmania University, Hyderabad, IndiaAbstract: Carbon nanotubes (CNTs are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity.Keywords: carbon nanotubes, cytotoxicity, functionalization, biomedical applications

  6. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  7. Carbon nanotubes as heat dissipaters in microelectronics

    DEFF Research Database (Denmark)

    Pérez Paz, Alejandro; García-Lastra, Juan María; Markussen, Troels;

    2013-01-01

    We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties...... of nanotubes in presence of an interface with various substances, including air and water. Comparison with previous works is established whenever is possible....

  8. Carbon Nanotube Paper-Based Electroanalytical Devices

    OpenAIRE

    Youngmi Koo; Vesselin N. Shanov; Yeoheung Yun

    2016-01-01

    Here, we report on carbon nanotube paper-based electroanalytical devices. A highly aligned-carbon nanotube (HA-CNT) array, grown using chemical vapor deposition (CVD), was processed to form bi-layered paper with an integrated cellulose-based Origami-chip as the electroanalytical device. We used an inverse-ordered fabrication method from a thick carbon nanotube (CNT) sheet to a thin CNT sheet. A 200-layered HA-CNT sheet and a 100-layered HA-CNT sheet are explored as a working electrode. The de...

  9. Ordered phases of cesium in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jeong Won; Hwang, Ho Jung; Song, Ki Oh; Choi, Won Young; Byun, Ki Ryang [Chung-Ang University, Seoul (Korea, Republic of); Kwon, Oh Keun [Semyung University, Jecheon (Korea, Republic of); Lee, Jun Ha [Sangmyung University, Chonan (Korea, Republic of); Kim, Won Woo [Juseong College, Cheongwon (Korea, Republic of)

    2003-10-15

    We investigate the structural phases of Cs in carbon nanotubes by using a structural optimization process applied to an atomistic simulation method. As the radius of the carbon nanotubes is increased, the structures are found in various phases from an atomic strand to multishell packs composed of coaxial cylindrical shells. Both helical structures and layered structures are found. The numbers of helical atom rows composed of coaxial tubes and the orthogonal vectors of the circular rolling of a triangular network can explain the structural phases of Cs in carbon nanotubes.

  10. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  11. Methods for producing reinforced carbon nanotubes

    Science.gov (United States)

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  12. Microcapsule carbon nanotube devices for therapeutic applications

    Science.gov (United States)

    Kulamarva, Arun; Raja, Pavan M. V.; Bhathena, Jasmine; Chen, Hongmei; Talapatra, Saikat; Ajayan, Pulickel M.; Nalamasu, Omkaram; Prakash, Satya

    2009-01-01

    Carbon nanotubes are a new class of nanomaterials that have immense potential in the field of biomedicine. Their ability to carry large quantities of therapeutic molecules makes them prime candidates for providing targeted delivery of therapeutics for use in various diseases. However, their utility is limited due to the problems faced during their delivery to target sites. This article for the first time describes the design of a novel microcapsule carbon nanotube targeted delivery device. This device has potential in the targeted delivery of carbon nanotubes in suitable membranes along with their cargo, safely and effectively to the target loci.

  13. Defect-Free Carbon Nanotube Coils.

    Science.gov (United States)

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos. PMID:26708150

  14. Methods for preparation of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rakov, Eduard G [D.I. Mendeleev Russian University of Chemical Technology, Moscow (Russian Federation)

    2000-01-31

    The most important methods of synthesis and purification of carbon nanotubes, a new form of material, are described. The prospects for increasing the scale of preparation processes and for more extensive application of nanotubes are evaluated. The bibliography includes 282 references.

  15. Charge Screening Effect in Metallic Carbon Nanotubes

    OpenAIRE

    Sasaki, K

    2001-01-01

    Charge screening effect in metallic carbon nanotubes is investigated in a model including the one-dimensional long-range Coulomb interaction. It is pointed out that an external charge which is being fixed spatially is screened by internal electrons so that the resulting object becomes electrically neutral. We found that the screening length is given by about the diameter of a nanotube.

  16. Carbon Nanotubes for Human Space Flight

    Science.gov (United States)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  17. The electrical conduction variation in stained carbon nanotubes

    Science.gov (United States)

    Sun, Shih-Jye; Wei Fan, Jun; Lin, Chung-Yi

    2012-01-01

    Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

  18. Covalent enzyme immobilization onto carbon nanotubes using a membrane reactor

    Science.gov (United States)

    Voicu, Stefan Ioan; Nechifor, Aurelia Cristina; Gales, Ovidiu; Nechifor, Gheorghe

    2011-05-01

    Composite porous polysulfone-carbon nanotubes membranes were prepared by dispersing carbon nanotubes into a polysulfone solution followed by the membrane formation by phase inversion-immersion precipitation technique. The carbon nanotubes with amino groups on surface were functionalized with different enzymes (carbonic anhydrase, invertase, diastase) using cyanuric chloride as linker between enzyme and carbon nanotube. The composite membrane was used as a membrane reactor for a better dispersion of carbon nanotubes and access to reaction centers. The membrane also facilitates the transport of enzymes to active carbon nanotubes centers for functionalization (amino groups). The functionalized carbon nanotubes are isolated by dissolving the membranes after the end of reaction. Carbon nanotubes with covalent immobilized enzymes are used for biosensors fabrications. The obtained membranes were characterized by Scanning Electron Microscopy, Thermal analysis, FT-IR Spectroscopy, Nuclear Magnetic Resonance, and functionalized carbon nanotubes were characterized by FT-IR spectroscopy.

  19. Coulomb drag in multiwall armchair carbon nanotubes

    DEFF Research Database (Denmark)

    Lunde, A.M.; Jauho, Antti-Pekka

    2004-01-01

    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  20. Microfabricated electroactive carbon nanotube actuators

    Science.gov (United States)

    Ahluwalia, Arti; Baughman, Ray H.; De Rossi, Danilo; Mazzoldi, Alberto; Tesconi, Mario; Tognetti, Alessandro; Vozzi, Giovanni

    2001-07-01

    A variety of microfabrication techniques have been developed at the University of Pisa. They are based either on pressure or piston actuated microsyringes or modified ink-jet printers. This work present the results of a study aimed at fabricating carbon nanotube (NT) actuators using micro-syringes. In order to prevent the nanotubes from aggregating into clumps, they were enclosed in a partially cross-linked polyvinylalcohol - polyallylamine matrix. After sonication the solution remained homogenously dispersed for about 40 minutes, which was sufficient time for deposition. Small strips of NT, about 5 mm across and 15 mm long were deposited. Following deposition, the films were baked at 80 degree(s)C and their thickness, impedance and mechanical resistance measured. The results indicate that 50 minutes of baking time is sufficient to give a constant resistivity of 1.12 x 10-2 (Omega) m per layer similar to a typical semiconductor, and each layer has a thickness of about 6 micrometers .

  1. Effects of charge distribution on water filling process in carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    MENG LingYi; LI QiKai; SHUAI ZhiGang

    2009-01-01

    Using umbrella sampling technique with molecular dynamics simulation, we investigated the nanoflu-idic transport of water in carbon nanotube (CNT). The simulations showed that a positive charge modi-fication to the carbon nanotube can slow down the water column growth process, while the negative charge modification to the carbon nanotube will, on the other hand, quicken the water column growth process. The free energy curves were obtained through the statistical process of water column growth under different charge distributions, and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels.

  2. Effects of charge distribution on water filling process in carbon nanotube

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using umbrella sampling technique with molecular dynamics simulation,we investigated the nanoflu-idic transport of water in carbon nanotube(CNT).The simulations showed that a positive charge modi-fication to the carbon nanotube can slow down the water column growth process,while the negative charge modification to the carbon nanotube will,on the other hand,quicken the water column growth process.The free energy curves were obtained through the statistical process of water column growth under different charge distributions,and the results indicated that these free energy curves can be employed to explain the dynamical process of water column growth in the nanosized channels.

  3. Purification of Carbon Nanotubes: Alternative Methods

    Science.gov (United States)

    Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

    2000-01-01

    Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

  4. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    Science.gov (United States)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  5. Deconvoluting hepatic processing of carbon nanotubes

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  6. Carbon nanotubes – becoming clean

    Directory of Open Access Journals (Sweden)

    Nicole Grobert

    2007-01-01

    Full Text Available Carbon nanotubes (CNTs are now well into their teenage years. Early on, theoretical predictions and experimental data showed that CNTs possess chemical and mechanical properties that exceed those of many other materials. This has triggered intense research into CNTs. A variety of production methods for CNTs have been developed; chemical modification, functionalization, filling, and doping have been achieved; and manipulation, separation, and characterization of individual CNTs is now possible. Today, products containing CNTs range from tennis rackets and golf clubs to vehicle fenders, X-ray tubes, and Li ion batteries. Breakthroughs for CNT-based technologies are anticipated in the areas of nanoelectronics, biotechnology, and materials science. In this article, I review the current situation in CNT production and highlight the importance of clean CNT material for the success of future applications.

  7. Piezoresistive Sensors Based on Carbon Nanotube Films

    Institute of Scientific and Technical Information of China (English)

    L(U) Jian-wei; WANG Wan-lu; LIAO Ke-jun; WANG Yong-tian; LIU CHang-lin; Zeng Qing-gao

    2005-01-01

    Piezoresistive effect of carbon nanotube films was investigated by a three-point bending test.Carbon nanotubes were synthesized by hot filament chemical vapor deposition.The experimental results showed that the carbon nanotubes have a striking piezoresistive effect.The relative resistance was changed from 0 to 10.5×10-2 and 3.25×10-2 for doped and undoped films respectively at room temperature when the microstrain under stress from 0 to 500. The gauge factors for doped and undoped carbon nanotube films under 500 microstrain were about 220 and 67 at room temperature, respectively, exceeding that of polycrystalline silicon (30) at 35℃.The origin of the resistance changes in the films may be attributed to a strain-induced change in the band gap for the doped tubes and the defects for the undoped tubes.

  8. Self Assembled Carbon Nanotube Enhanced Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to develop single wall carbon nanotube (SWCNT) based ultracapacitors for energy storage devices (ESD) application, using...

  9. A Thermal Model for Carbon Nanotube Interconnects

    Directory of Open Access Journals (Sweden)

    Clay Mayberry

    2013-04-01

    Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  10. Carbon nanotube polymer composition and devices

    Science.gov (United States)

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    2011-06-14

    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  11. Carbon nanotube heat-exchange systems

    Science.gov (United States)

    Hendricks, Terry Joseph; Heben, Michael J.

    2008-11-11

    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  12. Fermentation based carbon nanotube multifunctional bionic composites

    Science.gov (United States)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-06-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

  13. Fermentation based carbon nanotube multifunctional bionic composites

    Science.gov (United States)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  14. Catalyst deposition for the preparation of carbon nanotubes

    DEFF Research Database (Denmark)

    2013-01-01

    Disclosed is a method of depositing islands of catalyst with a predetermined density, wherein in said method comprises the steps of: obtaining a diffusion barrier covered nano patterned surface comprising a plurality of plateaus, having a density of plateaus dependent on the predetermined density...... patterned surface is configured to ensure that no more than a single island of catalyst is formed on each plateau, so that a sub sequent growth of carbon nanotubes from the deposited islands result in that no more than a single carbon nanotube is grown from each plateau....

  15. Carbon nanotube temperature and pressure sensors

    Science.gov (United States)

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  16. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.

    2016-10-25

    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  17. Controlled Deposition and Alignment of Carbon Nanotubes

    Science.gov (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  18. ALUMINUM FOIL REINFORCED BY CARBON NANOTUBES

    OpenAIRE

    A. V. Alekseev; PREDTECHENSKIY M.R.

    2016-01-01

    In our research, the method of manufacturing an Al-carbon nanotube (CNT) composite by hot pressing and cold rolling was attempted. The addition of one percent of multi-walled carbon nanotubes synthesized by OCSiAl provides a significant increase in the ultimate tensile strength of aluminum. The tensile strength of the obtained composite material is at the tensile strength level of medium-strength aluminum alloys.

  19. Analysis of Carbon Nanotube Field-Effect-Transistors (FETs)

    Science.gov (United States)

    Yamada, Toshishige

    1999-01-01

    This five page presentation is grouped into 11 numbered viewgraphs, most of which contain one or more diagrams. Some of the diagrams are accompanied by captions, including: 2) Nanotube FET by Delft, IBM; 3) Nanotube FET/Standard MOSFET; 5) Saturation with carrier-carrier; 7) Electronic properties of carbon nanotube; 8) Theoretical nanotube FET characteristics; 11) Summary: Delft and IBM nanotube FET analysis.

  20. Carbon Nanotubes for Thin Film Transistor: Fabrication, Properties, and Applications

    Directory of Open Access Journals (Sweden)

    Yucui Wu

    2013-01-01

    Full Text Available We review the present status of single-walled carbon nanotubes (SWCNTs for their production and purification technologies, as well as the fabrication and properties of single-walled carbon nanotube thin film transistors (SWCNT-TFTs. The most popular SWCNT growth method is chemical vapor deposition (CVD, including plasma-enhanced chemical vapor deposition (PECVD, floating catalyst chemical vapor deposition (FCCVD, and thermal CVD. Carbon nanotubes (CNTs used to fabricate thin film transistors are sorted by electrical breakdown, density gradient ultracentrifugation, or gel-based separation. The technologies of applying CNT random networks to work as the channels of SWCNT-TFTs are also reviewed. Excellent work from global researchers has been benchmarked and analyzed. The unique properties of SWCNT-TFTs have been reviewed. Besides, the promising applications of SWCNT-TFTs have been explored. Finally, the key issues to be solved in future have been summarized.

  1. ON THE CONTINUUM MODELING OF CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    张鹏; 黄永刚; Philippe H.Geubelle; 黄克智

    2002-01-01

    We have recently proposed a nanoscale continuum theory for carbonnanotubes. The theory links continuum analysis with atomistic modeling by incor-porating interatomic potentials and atomic structures of carbon nanotubes directlyinto the constitutive law. Here we address two main issues involved in setting upthe nanoscale continuum theory for carbon nanotubes, namely the multi-body in-teratomic potentials and the lack of centrosymmetry in the nanotube structure. Weexplain the key ideas behind these issues in establishing a nanoscale continuum theoryin terms of interatomic potentials and atomic structures.

  2. Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes

    OpenAIRE

    Deepak, FL; Govindaraj, A.; Rao, CNR

    2006-01-01

    Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Y-junction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallic-thiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon nanotubes with Y-junctions. Pyrolysis-of organometallic-hydrocarbon mixtures, in the absence of water vapour, only gives ...

  3. Method for nano-pumping using carbon nanotubes

    Science.gov (United States)

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  4. Fast readout of carbon nanotube mechanical resonators

    Science.gov (United States)

    Meerwaldt, Harold; Singh, Vibhor; Schneider, Ben; Schouten, Raymond; van der Zant, Herre; Steele, Gary

    2013-03-01

    We perform fast readout measurements of carbon nanotube mechanical resonators. Using an electronic mixing scheme, we can detect the amplitude of the mechanical motion with an intermediate frequency (IF) of 46 MHz and a timeconstant of 1 us, up to 5 orders of magnitude faster than before. Previous measurements suffered from a low bandwidth due to the combination of the high resistance of the carbon nanotube and a large stray capacitance. We have increased the bandwidth significantly by using a high-impedance, close-proximity HEMT amplifier. The increased bandwidth should allow us to observe the nanotube's thermal motion and its transient response, approaching the regime of real-time detection of the carbon nanotube's mechanical motion.

  5. Manipulation and cutting of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nanomanipulation plays an important role in nanofabrication, it is also a technology necessary in exploring the secrets of nanoworld, and it thus beco mesa start point to research future nanomachine. In this study, manipulation and cutting of carbon nanotubes have been conducted in order to examine whether we can move a nanocomponent from one site to another by using the tip of atomic fo rce microscope (AFM). The technique may also be valuable for providing the const ructive materials of nanofabrication. While exploring the method for manipulatin g and cutting of nanotubes, some new phenomena have been observed during the process. Results show that carbon nanotubes present a feature of deformation combin ing bending and distortion when subjected to large mechanical forces exerted by the tip of AFM. In special cases, long carbon nanotubes can be cut into two part s, by which we can remove the part where crystal lattice is flawed, and therefor e a perfect nanocomponent can be obtained.

  6. Fabrication of nylon-6/carbon nanotube composites

    Science.gov (United States)

    Xu, C.; Jia, Z.; Wu, D.; Han, Q.; Meek, T.

    2006-05-01

    A new technique to fabricate nylon-6/carbon nanotube (PA6/CNT) composites is presented. The method involves a pretreatment of carbon nanotubes synthesized by catalytic pyrolysis of hydrocarbon and an improved in-situ process for mixing nanotubes with the nylon 6 matrix. A good bond between carbon nanotubes and the nylon-6 matrix is obtained. Mechanical property measurements indicate that the tensile strength of PA6/CNT composites is improved significantly while the toughness and elongation are somewhat compromised. Scanning electron microscopy (SEM) analysis of the fractured tensile specimens reveals cracking initiated at the wrapping of the CNTs PA6 layer/PA6 matrix interface rather than at the PA6/CNT interface.

  7. Center for Applications of Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Resasco, Daniel E

    2008-02-21

    This report describes the activities conducted under a Congressional Direction project whose goal was to develop applications for Single-walled carbon nanotubes, under the Carbon Nanotube Technology Center (CANTEC), a multi-investigator program that capitalizes on OU’s advantageous position of having available high quality carbon nanotubes. During the first phase of CANTEC, 11 faculty members and their students from the College of Engineering developed applications for carbon nanotubes by applying their expertise in a number of areas: Catalysis, Reaction Engineering, Nanotube synthesis, Surfactants, Colloid Chemistry, Polymer Chemistry, Spectroscopy, Tissue Engineering, Biosensors, Biochemical Engineering, Cell Biology, Thermal Transport, Composite Materials, Protein synthesis and purification, Molecular Modeling, Computational Simulations. In particular, during this phase, the different research groups involved in CANTEC made advances in the tailoring of Single-Walled Carbon Nanotubes (SWNT) of controlled diameter and chirality by Modifying Reaction Conditions and the Nature of the catalyst; developed kinetic models that quantitatively describe the SWNT growth, created vertically oriented forests of SWNT by varying the density of metal nanoparticles catalyst particles, and developed novel nanostructured SWNT towers that exhibit superhydrophobic behavior. They also developed molecular simulations of the growth of Metal Nanoparticles on the surface of SWNT, which may have applications in the field of fuell cells. In the area of biomedical applications, CANTEC researchers fabricated SWNT Biosensors by a novel electrostatic layer-by-layer (LBL) deposition method, which may have an impact in the control of diabetes. They also functionalized SWNT with proteins that retained the protein’s biological activity and also retained the near-infrared light absorbance, which finds applications in the treatment of cancer.

  8. Modeling of carbon nanotubes and carbon nanotube-polymer composites

    Science.gov (United States)

    Pal, G.; Kumar, S.

    2016-01-01

    In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

  9. Carbon Nanotube and Graphene Nanoelectromechanical Systems

    Science.gov (United States)

    Aleman, Benjamin Jose

    One-dimensional and two-dimensional forms of carbon are composed of sp 2-hybridized carbon atoms arranged in a regular hexagonal, honeycomb lattice. The two-dimensional form, called graphene, is a single atomic layer of hexagonally-bonded carbon atoms. The one-dimensional form, known as a carbon nanotube, can be conceptualized as a rectangular piece of graphene wrapped into a seamless, high-aspect-ratio cylinder or tube. This dissertation addresses the physics and applied physics of these one and two-dimensional carbon allotropes in nanoelectromechanical systems (NEMS). First, we give a theoretical background on the electrodynamics and mechanics of carbon nanotube NEMS. We then describe basic experimental techniques, such as electron and scanning probe microscopy, that we then use to probe static and dynamic mechanical and electronic behavior of the carbon nanotube NEMS. For example, we observe and control non-linear beam bending and single-electron quantum tunneling effects in carbon nanotube resonators. We then describe parametric amplification, self-oscillation behavior, and dynamic, non-linear effects in carbon nanotube mechanical resonators. We also report a novel approach to fabricate carbon nanotube atomic force microscopy (AFM) probes, and show that they can lead to exceptional lateral resolution enhancement in AFM when imaging both hard and soft (biological) materials. Finally, we describe novel fabrication techniques for large-area, suspended graphene membranes, and utilize these membranes as TEM-transparent, AFM-compatible, NEMS resonators. Laser-driven mechanical vibrations of the graphene resonators are detected by optical interferometry and several vibration harmonics are observed. A degeneracy splitting is observed in the vibrational modes of square-geometry resonators. We then attribute the observed degeneracy splitting to local mass inhomogeneities and membrane defects, and find good overall agreement with the developed theoretical model.

  10. Carbon nanotubes and graphene towards soft electronics

    Science.gov (United States)

    Chae, Sang Hoon; Lee, Young Hee

    2014-04-01

    Although silicon technology has been the main driving force for miniaturizing device dimensions to improve cost and performance, the current application of Si to soft electronics (flexible and stretchable electronics) is limited due to material rigidity. As a result, various prospective materials have been proposed to overcome the rigidity of conventional Si technology. In particular, nano-carbon materials such as carbon nanotubes (CNTs) and graphene are promising due to outstanding elastic properties as well as an excellent combination of electronic, optoelectronic, and thermal properties compared to conventional rigid silicon. The uniqueness of these nano-carbon materials has opened new possibilities for soft electronics, which is another technological trend in the market. This review covers the recent progress of soft electronics research based on CNTs and graphene. We discuss the strategies for soft electronics with nano-carbon materials and their preparation methods (growth and transfer techniques) to devices as well as the electrical characteristics of transparent conducting films (transparency and sheet resistance) and device performances in field effect transistor (FET) (structure, carrier type, on/off ratio, and mobility). In addition to discussing state of the art performance metrics, we also attempt to clarify trade-off issues and methods to control the trade-off on/off versus mobility). We further demonstrate accomplishments of the CNT network in flexible integrated circuits on plastic substrates that have attractive characteristics. A future research direction is also proposed to overcome current technological obstacles necessary to realize commercially feasible soft electronics.

  11. Carbon Nanotube-Based Synthetic Gecko Tapes

    Science.gov (United States)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  12. Preparation and characterization of carbon nanotube-hybridized carbon fiber to reinforce epoxy composite

    International Nuclear Information System (INIS)

    Highlights: → CNTs were uniformly grown onto the carbon fibers. → No obvious mechanical properties of carbon fiber were observed after CNT growth. → The IFSS of multiscale epoxy composite was measured by single fiber pull-out tests. → Observing fractography of composite, the fracture modes of CNTs were discussed. -- Abstract: The multiscale carbon nanotube-hybridized carbon fiber was prepared by a newly developed aerosol-assisted chemical vapour deposition. Scanning electron microscopy and transmission electron microscope were carried out to characterize this multiscale material. Compared with the original carbon fibers, the fabrication of this hybrid fiber resulted in an almost threefold increase of BET surface area to reach 2.22 m2/g. Meanwhile, there was a slight degradation of fiber tensile strength within 10%, while the fiber modulus was not significantly affected. The interfacial shearing strength of a carbon fiber-reinforced polymer composite with carbon nanotube-hybridized carbon fiber and an epoxy matrix was determined from the single fiber pull-out tests of microdroplet composite. Due to an efficient increase of load transfer at the fiber/matrix interfaces, the interracial shear strength of composite reinforced by carbon nanotube-hybridized carbon fiber is almost 94% higher than that of one reinforced by the original carbon fiber. Based on the fractured morphologies of the composites, the interfacial reinforcing mechanisms were discussed through proposing different types of carbon nanotube fracture modes along with fiber pulling out from epoxy composites.

  13. Carbon nanotube based NEMS actuators and sensors

    Science.gov (United States)

    Forney, Michael; Poler, Jordan

    2011-03-01

    Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

  14. Release characteristics of selected carbon nanotube polymer composites

    Science.gov (United States)

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  15. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  16. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  17. Carbon Nanotube-Based Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  18. Carbon Nanotube Tower-Based Supercapacitor

    Science.gov (United States)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  19. Synergistic strengthening effect of nanocrystalline copper reinforced with carbon nanotubes

    Science.gov (United States)

    Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Wang, Fu-Chi; Li, Sheng-Lin; Korznikov, Elena; Zhao, Xiu-Chen; Liu, Ying; Liu, Zhen-Feng; Kang, Zhe

    2016-05-01

    In this study, a novel multi-walled carbon nanotubes reinforced nanocrystalline copper matrix composite with super high strength and moderate plasticity was synthesized. We successfully overcome the agglomeration problem of the carbon nanotubes and the grain growth problem of the nanocrystalline copper matrix by combined use of the electroless deposition and spark plasma sintering methods. The yield strength of the composite reach up to 692 MPa, which is increased by 2 and 5 times comparing with those of the nanocrystalline and coarse copper, respectively. Simultaneously, the plasticity of the composite was also significantly increased in contrast with that of the nanocrystalline copper. The increase of the density of the carbon nanotubes after coating, the isolation effect caused by the copper coating, and the improvement of the compatibility between the reinforcements and matrix as well as the effective control of the grain growth of the copper matrix all contribute to improving the mechanical properties of the composite. In addition, a new strengthening mechanism, i.e., the series-connection effect of the nanocrystalline copper grains introduced by carbon nanotubes, is proposed to further explain the mechanical behavior of the nanocomposite.

  20. Carbon Nanotubes and Chronic Granulomatous Disease

    Directory of Open Access Journals (Sweden)

    Barbara P. Barna

    2014-06-01

    Full Text Available Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

  1. Optical trapping of carbon nanotubes and graphene

    OpenAIRE

    Vasi, S.; M. A. Monaca; Donato, M. G.; Bonaccorso, F.; Privitera, G; Trushkevych, O.; G. Calogero; Fazio, B.; Irrera, A.; M.A. Iati'; Saija, R.; Denti, P.; F. Borghese; Jones, P H; Ferrari, A. C.

    2011-01-01

    We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fuctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double ...

  2. Efficiently Dispersing Carbon Nanotubes in Polyphenylene Sulfide

    OpenAIRE

    Sommer, Kevin M; Pipes, R. Byron

    2013-01-01

    Thermal plastics are replacing conventional metals in the aerospace, sporting, electronics, and other industries. Thermal plastics are able to withstand relatively high temperatures, have good fatigue properties, and are lighter than metals. Unfortunately, they are not very electrically conductive. However, adding carbon nanotubes to thermal plastics such as polyphenylene sulfide (PPS) can drastically increase the plastic's conductivity at a low weight percent of nanotubes called the percolat...

  3. Thermal Transport in Carbon Nanotubes

    Science.gov (United States)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  4. Does water dope carbon nanotubes?

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Robert A.; Payne, Michael C. [Theory of Condensed Matter Group, Cavendish Laboratory, Cambridge (United Kingdom); Mostofi, Arash A. [Department of Materials and Department of Physics, and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    2014-10-28

    We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10{sup −4} e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

  5. Elastomer Reinforced with Carbon Nanotubes

    Science.gov (United States)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  6. Integrating nanotubes into microsystems with electron beam lithography and in situ catalytically activated growth

    DEFF Research Database (Denmark)

    Gjerde, Kjetil; Fornés-Mora, Marc; Kjelstrup-Hansen, Jakob;

    2006-01-01

    Integration of freestanding wire-like structures such as multi walled carbon nanotubes (MWCNT) into microsystems has many potential applications. Devices such as AFM tips or improved electrodes for conductivity measurements are obvious candidates. Catalytically activated growth opens up...

  7. Different Technical Applications of Carbon Nanotubes.

    Science.gov (United States)

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  8. Edge effects in finite elongated carbon nanotubes

    CERN Document Server

    Hod, O; Scuseria, G E; Hod, Oded; Peralta, Juan E.; Scuseria, Gustavo E.

    2006-01-01

    The importance of finite-size effects for the electronic structure of long zigzag and armchair carbon nanotubes is studied. We analyze the electronic structure of capped (6,6), (8,0), and (9,0) single walled carbon nanotubes as a function of their length up to 60 nm, using a divide and conquer density functional theory approach. For the metallic nanotubes studied, most of the physical features appearing in the density of states of an infinite carbon nanotube are recovered at a length of 40 nm. The (8,0) semi-conducting nanotube studied exhibits pronounced edge effects within the energy gap that scale as the inverse of the length of the nanotube. As a result, the energy gap reduces from the value of ~1 eV calculated for the periodic system to a value of ~0.25 eV calculated for a capped 62 nm long CNT. These edge effects are expected to become negligible only at tube lengths exceeding 6 micrometers. Our results indicate that careful tailoring of the nature of the system and its capping units should be applied w...

  9. Chitosan-mediated synthesis of carbon nanotube-gold nanohybrids

    Institute of Scientific and Technical Information of China (English)

    GRAVEL; Edmond; FOILLARD; Stéphanie; DORIS; Eric

    2010-01-01

    Metal-nanotube nanohybrids were produced by in situ synthesis and stabilization of gold nanoparticles on chitosan-functionalized carbon nanotubes.The formation of gold nanoparticles from tetrachloroauric acid was observed after only a few minutes of contact with the functionalized nanotubes,at room temperature.These results suggest that adsorption of chitosan at the surface of carbon nanotubes permits smooth reduction of the metallic salt and efficient anchoring of gold nanoparticles to the nanotubes.

  10. Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. G. Larrude

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

  11. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  12. Deposition of the platinum crystals on the carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new technique and the affecting factors for depositing platinum on the carbon nanotubes were investigated. The results show that the deposited platinum crystals in the atmosphere of hydrogen or nitrogen have a small size and a homogeneous distribution on the surface of the carbon nanotubes. The pretreatment would decrease the platinum particles on the carbon nanotubes significantly.

  13. Decoration of activated carbon nanotubes by assembling nano-silver

    Institute of Scientific and Technical Information of China (English)

    Chen-sha Li; Bin-song Wang; Ying-jie Qiao; Wei-zhe Lu; Ji Liang

    2009-01-01

    A facile solution processed strategy of synthesizing nano silver assembled on carbon nanotubes (CNTs) at room tempera-ture was put forward. Activated carbon nanotubes were used as precursors for preparing silver-decorated nanotubes. The nature of the decorated nanotubes was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and en-ergy-dispersive X-ray spectroscopy (EDX). The inert surfaces of carbon nanotubes were activated by introducing catalytic nuclei via an oxidation-sensitization-activation approach. Activated carbon nanotubes catalyzed the metal deposition specifically onto their surfaces upon immersion in electroless plating baths. The method produced nanotubes decorated with silver. The extent of silver decoration was found to be dependent on fabrication conditions. Dense nano silver assembled on nanotube surfaces could be ob-tained by keeping a low reaction rate in the solution phase. The results here show that this method is an efficient and simple means of achieving carbon nanotubes being assembled by nano metal.

  14. Low-temperature growth of single-walled carbon nanotube using Al2O3/Pd/Al2O3 multilayer catalyst by alcohol gas source method at high vacuum

    Science.gov (United States)

    Kiribayashi, Hoshimitsu; Ogawa, Seigo; Kozawa, Akinari; Saida, Takahiro; Naritsuka, Shigeya; Maruyama, Takahiro

    2016-06-01

    We carried out single-walled carbon nanotube (SWCNT) growth at 500 and 600 °C using Al2O3/Pd/Al2O3 multilayer catalysts on SiO2/Si substrates by the alcohol gas source method. When the ethanol pressures were 1 × 10‑4 and 1 × 10‑3 Pa, radial-breathing-mode (RBM) peaks and sharp G band peaks appeared in Raman spectra, indicating the growth of SWCNTs even at 500 °C. When the growth temperature and ethanol pressure were 500 °C and 1 × 10‑4 Pa, respectively, the growth rate decreased gradually with the growth time, but the SWCNT growth continued for more than 4 h and the diameter distribution changed as the growth proceeded. X-ray photoelectron spectroscopy measurements showed that oxidized Pd catalyst particles were reduced to metallic states after the SWCNT growth started.

  15. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Carbon nanotube suspensions, dispersions, & composites

    Science.gov (United States)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  17. Graphene-carbon nanotube hybrid materials and use as electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

    2016-09-27

    Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.

  18. Evolution of gold thin films to nanoparticles using plasma ion bombardment and their use as a catalyst for carbon nanotube growth

    International Nuclear Information System (INIS)

    We investigate the evolution of Au thin films to nanoparticles caused by plasma ion bombardment and report their validity as a catalyst on the growth of carbon nanotubes (CNTs). The Au thin films having 1–50 Å thickness ranges were precisely prepared by electron beam deposition. The plasma ion bombardments with the plasma power from 5 to 15 W were performed at 500 °C for 10 min under 1.33 × 102 Pa of Ar to investigate the effects of plasma power on the surface structures. It is interesting that the mean size of Au nanoparticles increased as plasma power gets high in the thinner film cases, which might be the results of sputtering and surface diffusion-related aggregation. On the contrary, the mean particle size of the thicker films decreased at lower plasma power regime due to the sputtering, then, increased again at the highest plasma power, which might be caused by the diffusion-induced aggregation of the films. Finally, to investigate the catalytic ability of the thin film-induced Au nanoparticles, we grew CNTs by a thermal chemical vapor deposition with a methane source. It was found that the Au nanoparticles obtained from the plasma-treated 5 Å thick films act as an efficient catalyst for the growth of single-walled CNTs. - Highlights: • We report the evolution of Au thin films to nanoparticles by plasma treatment. • The mean size of Au nanoparticles increased with increasing plasma power. • The nanoparticle size increases by sputtering and diffusion-induced aggregation. • The plasma-treated 5 Å thick films act as an efficient catalyst for SWNTs growth

  19. Carbon nanotube growth from catalytic nano-clusters formed by hot-ion-implantation into the SiO{sub 2}/Si interface

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Yasushi, E-mail: yhoshino@kanagawa-u.ac.jp [Department of Information Sciences, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Arima, Hiroki; Yokoyama, Ai; Saito, Yasunao; Nakata, Jyoji [Department of Information Sciences, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan)

    2012-07-01

    We have studied growth of chirality-controlled carbon nanotubes (CNTs) from hot-implantation-formed catalytic nano-clusters in a thermally grown SiO{sub 2}/Si substrate. This procedure has the advantage of high controllability of the diameter and the number of clusters by optimizing the conditions of the ion implantation. In the present study, Co{sup +} ions with ion dose of 8 Multiplication-Sign 10{sup 16} cm{sup -2} are implanted in the vicinity of the SiO{sub 2}/Si interface at 300 Degree-Sign C temperature. The implanted Co atoms located in the SiO{sub 2} layer has an amorphous-like structure with a cluster diameter of several nm. In contrast, implanted Co atoms in the Si substrate are found to take a cobalt silicide structure, confirmed by the high-resolution image of transmission electron microscope. CNTs are grown by microwave-plasma-enhanced chemical vapor deposition. We have confirmed a large amount of vertically-aligned multi-walled CNTs from the Co nano-clusters formed by the hot-ion-implantation near the SiO{sub 2}/Si interface.

  20. Modeling of the HiPco process for carbon nanotube production. II. Reactor-scale analysis

    Science.gov (United States)

    Gokcen, Tahir; Dateo, Christopher E.; Meyyappan, M.

    2002-01-01

    The high-pressure carbon monoxide (HiPco) process, developed at Rice University, has been reported to produce single-walled carbon nanotubes from gas-phase reactions of iron carbonyl in carbon monoxide at high pressures (10-100 atm). Computational modeling is used here to develop an understanding of the HiPco process. A detailed kinetic model of the HiPco process that includes of the precursor, decomposition metal cluster formation and growth, and carbon nanotube growth was developed in the previous article (Part I). Decomposition of precursor molecules is necessary to initiate metal cluster formation. The metal clusters serve as catalysts for carbon nanotube growth. The diameter of metal clusters and number of atoms in these clusters are some of the essential information for predicting carbon nanotube formation and growth, which is then modeled by the Boudouard reaction with metal catalysts. Based on the detailed model simulations, a reduced kinetic model was also developed in Part I for use in reactor-scale flowfield calculations. Here this reduced kinetic model is integrated with a two-dimensional axisymmetric reactor flow model to predict reactor performance. Carbon nanotube growth is examined with respect to several process variables (peripheral jet temperature, reactor pressure, and Fe(CO)5 concentration) with the use of the axisymmetric model, and the computed results are compared with existing experimental data. The model yields most of the qualitative trends observed in the experiments and helps to understanding the fundamental processes in HiPco carbon nanotube production.

  1. Geometric and electronic structure of carbon nanotube networks: 'super'-carbon nanotubes

    Science.gov (United States)

    Coluci, V. R.; Galvão, D. S.; Jorio, A.

    2006-02-01

    Structures of the so-called super-carbon nanotubes are proposed. These structures are built from single walled carbon nanotubes connected by Y-like junctions forming a 'super'-sheet that is then rolled into a seamless cylinder. Such a procedure can be repeated several times, generating a fractal structure. This procedure is not limited to carbon nanotubes, and can be easily modified for application to other systems. Tight binding total energy and density of states calculations showed that the 'super'-sheets and tubes are stable and predicted to present metallic and semiconducting behaviour.

  2. Boron-Filled Hybrid Carbon Nanotubes.

    Science.gov (United States)

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  3. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  4. Modelling Carbon Nanotubes-Based Mediatorless Biosensor

    Directory of Open Access Journals (Sweden)

    Julija Razumiene

    2012-07-01

    Full Text Available This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments: a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate.

  5. Modelling carbon nanotubes-based mediatorless biosensor.

    Science.gov (United States)

    Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

    2012-01-01

    This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

  6. Detection of gas atoms with carbon nanotubes

    Science.gov (United States)

    Arash, B.; Wang, Q.

    2013-05-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  7. High frequency conductivity in carbon nanotubes

    Directory of Open Access Journals (Sweden)

    S. S. Abukari

    2012-12-01

    Full Text Available We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ωB for metallic zigzag CNs and ω < ωB for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  8. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  9. Carbon Nanotubes Synthesis Through Gamma Radiation

    Science.gov (United States)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  10. Investigating the effect of carbon nanotube diameter and wall number in carbon nanotube/silicon heterojunction solar cells

    OpenAIRE

    Tom Grace; LePing Yu; Christopher Gibson; Daniel Tune; Huda Alturaif; Zeid Al Othman; Joseph Shapter

    2016-01-01

    Suspensions of single-walled, double-walled and multi-walled carbon nanotubes (CNTs) were generated in the same solvent at similar concentrations. Films were fabricated from these suspensions and used in carbon nanotube/silicon heterojunction solar cells and their properties were compared with reference to the number of walls in the nanotube samples. It was found that single-walled nanotubes generally produced more favorable results; however, the double and multi-walled nanotube films used in...

  11. Molecular Dynamics Modeling of Carbon Nanotubes and Their Composites

    Science.gov (United States)

    Jensen, Lars R.; Pyrz, Ryszard

    2004-06-01

    The tensile modulus of individual nanotubes and nanotube-polypropylene composites has been determined using molecular dynamics simulations. Simulations of individual single-walled carbon nanotubes showed that their tensile modulus was dependent on the tube structure and the diameter if the diameter was below 1,6 nm. The tensile modulus was determined for an infinite single-walled carbon nanotube embedded in an amorphous polypropylene matrix and for a finite and capped single-walled carbon nanotube embedded in a polypropylene matrix. For the infinite nanotube-polypropylene system the modulus was found to correspond to the one given by the Voigt approximation. For the finite nanotube-polypropylene system the reinforcing effect of the nanotube was not very pronounced. A pull out simulation showed that the length of the nanotube in the simulation was much smaller than the critical length and hence no load transfer between the nanotube and the matrix existed.

  12. Effect of oxygen adsorption on the electrochemical oxidative corrosion of single-walled carbon nanotubes

    OpenAIRE

    Tominaga, Masato; Yatsugi, Yuto; Togami, Makoto; トミナガ, マサト; ヤツギ, ユウト; トガミ, マコト; 冨永, 昌人; 矢次, 祐人; 戸上, 純

    2014-01-01

    The effect of adsorbed molecular oxygen on the oxidative corrosion of single-walled carbon nanotubes in aqueous solution was investigated by Raman spectroscopy. Adsorbed molecular oxygen affected nucleation and growth in the electrochemical oxidative corrosion of single-walled carbon nanotubes in aqueous electrolyte. Nucleation and growth began at defect sites in the presence of adsorbed oxygen, but occurred randomly in the absence of adsorbed oxygen. This insight furthers our understanding o...

  13. A carbon nanotube optical rectenna

    Science.gov (United States)

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L.; Cola, Baratunde A.

    2015-12-01

    An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ˜2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (˜10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation.

  14. Micromechanics of carbon nanotube turfs

    Science.gov (United States)

    Torabi, Hamid

    Complex structures consisting of intertwined, nominally vertical carbon nanotubes (CNTs) are called turfs. Unique electrical, thermal, optical, and permeability properties of these turfs have attracted growing attention during the past decade, and have rendered them as appropriate candidates for applications such as contact thermal switches. These properties are controlled by the details of the turf microstructures. Due to the application of the turfs in different fields, they are subjected to different loading conditions. Deformation changes the microstructure of a CNT turf, which results in change of effective properties. Many researchers have recently studied the collective mechanical behavior of CNT turfs to compression loading, as this behavior determines their performance. However, their complex and intertwined structure must be investigated in more details to find the relation between their deformation and their underlying morphology. Under uniform compression experiments, CNT turfs exhibit irreversible collective buckling of a layer preceded by reorientation of CNT segments. Experimentally observed independence of the buckling stress and the buckling wavelength on the turf width suggests the existence of an intrinsic material length. To investigate the relationship the macroscopic material properties and the statistical parameters describing the nano-scale geometry of the turf (tortuosity, density and connectivity) we develop a nano-scale computational model, based on the representation of CNT segments as elastica finite elements with van der Waals interactions. The virtual turfs are generated by means of a constrained random walk algorithm and subsequent relaxation. The resulting computational model is robust and is capable of modeling the collective behavior of CNTs. We first establish the dependence of statistical parameters on the computational parameters used for turf generation, then establish relationships between post-buckling stress, initial

  15. Self-Assembly of Graphene on Carbon Nanotube Surfaces

    Science.gov (United States)

    Li, Kaiyuan; Eres, Gyula; Howe, Jane; Chuang, Yen-Jun; Li, Xufan; Gu, Zhanjun; Zhang, Litong; Xie, Sishen; Pan, Zhengwei

    2013-08-01

    The rolling up of a graphene sheet into a tube is a standard visualization tool for illustrating carbon nanotube (CNT) formation. However, the actual processes of rolling up graphene sheets into CNTs in laboratory syntheses have never been demonstrated. Here we report conformal growth of graphene by carbon self-assembly on single-wall and multi-wall CNTs using chemical vapor deposition (CVD) of methane without the presence of metal catalysts. The new graphene layers roll up into seamless coaxial cylinders encapsulating the existing CNTs, but their adhesion to the primary CNTs is weak due to the existence of lattice misorientation. Our study shows that graphene nucleation and growth by self-assembly of carbon on the inactive carbon basal plane of CNTs occurs by a new mechanism that is markedly different from epitaxial growth on metal surfaces, opening up the possibility of graphene growth on many other non-metal substrates by simple methane CVD.

  16. Structural and biological properties of carbon nanotube composite films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail: roger.narayan@mse.gatech.edu; Berry, C.J. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States); Brigmon, R.L. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2005-11-20

    Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 deg. C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp{sup 2}-bonded concentric ribbons that are wrapped approximately 15 deg. normal to the silicon substrate. The interlayer order in this material extends to approximately 15-30 A. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.

  17. A tunable carbon nanotube electromechanical oscillator

    Science.gov (United States)

    Sazonova, Vera; Yaish, Yuval; Üstünel, Hande; Roundy, David; Arias, Tomás A.; McEuen, Paul L.

    2004-09-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. In particular, NEMS oscillators have been proposed for use in ultrasensitive mass detection, radio-frequency signal processing, and as a model system for exploring quantum phenomena in macroscopic systems. Perhaps the ultimate material for these applications is a carbon nanotube. They are the stiffest material known, have low density, ultrasmall cross-sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus may be able to sense its own motion. In spite of this great promise, a room-temperature, self-detecting nanotube oscillator has not been realized, although some progress has been made. Here we report the electrical actuation and detection of the guitar-string-like oscillation modes of doubly clamped nanotube oscillators. We show that the resonance frequency can be widely tuned and that the devices can be used to transduce very small forces.

  18. Magnetoresistance of Multiwalled Carbon Nanotube Yarns

    Institute of Scientific and Technical Information of China (English)

    SHENG Lei-Mei; GAO Wei; CAO Shi-Xun; ZHANG Jin-Cang

    2008-01-01

    We measure zero-field resistivity and magnetoresistance of multiwalled carbon nanotube yarns (CNTYs). The CNTYs are drawn from superaligned multiwalled carbon nanotube arrays synthesized by the low-pressure chemical vapour deposition method. The zero-field resistivity shows a logarithmic decrease from 2 K to 300 K. In the presence of a magnetic field applied perpendicular to the yarn axis, a pronounced negative magnetoresistance is observed. A magnetoresistance ratio of 22% is obtained. These behaviours can be explained by the weak localization effect.

  19. Carbon nanotubes for in vivo cancer nanotechnology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The latest progress of using carbon nanotubes(CNTs) for in vivo cancer nanotechnology is reviewed.CNTs can be functionalized by either covalent or non-covalent chemistry to produce functional bioconjugates for many in vivo applications.In vivo behaviors and toxicology studies of CNTs are summarized,suggesting no significant toxicity of well functionalized CNTs to the treated mice.Owing to their unique chemical and physical properties,CNTs,especially single-walled carbon nanotubes(SWNTs),have been widely used for various modalities of in vivo cancer treatment and imaging.Future development of CNT-based nanomedicine may bring novel opportunities to cancer diagnosis and therapy.

  20. Laser ablative synthesis of carbon nanotubes

    Science.gov (United States)

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  1. Piezoresistive effect in carbon nanotube films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The piezoresistive effect of the pristine carbon nanotube (CNT) films has been studied. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The piezoresistive effect in the pristine CNT films was studied by a three-point bending test. The gauge factor for the pristine CNT films under 500 microstrains was found to be at least 65 at room temperature, and increased with temperature, exceeding that of polycrystalline silicon (30) at 35℃. The origin of the piezoresistivity in CNT films may be ascribed to a pressure-induced change in the band gap and the defects.

  2. Graphene/single-walled carbon nanotube hybrids: one-step catalytic growth and applications for high-rate Li-S batteries.

    Science.gov (United States)

    Zhao, Meng-Qiang; Liu, Xiao-Fei; Zhang, Qiang; Tian, Gui-Li; Huang, Jia-Qi; Zhu, Wancheng; Wei, Fei

    2012-12-21

    The theoretically proposed graphene/single-walled carbon nanotube (G/SWCNT) hybrids by placing SWCNTs among graphene planes through covalent C-C bonding are expected to have extraordinary physical properties and promising engineering applications. However, the G/CNT hybrids that have been fabricated differ greatly from the proposed G/SWCNT hybrids because either the covalent C-C bonding is not well constructed or only multiwalled CNTs/carbon nanofibers rather than SWCNTs are available in the hybrids. Herein, a novel G/SWCNT hybrid was successfully fabricated by a facile catalytic growth on layered double hydroxide (LDH) at a high temperature over 950 °C. The thermally stable Fe nanoparticles and the uniform structure of the calcined LDH flakes are essential for the simultaneously catalytic deposition of SWCNTs and graphene. The SWCNTs and the CVD-grown graphene, as well as the robust connection between the SWCNTs and graphene, facilitated the construction of a high electrical conductive pathway. The internal spaces between the two stacked graphene layers and among SWCNTs offer room for sulfur storage. Therefore, the as obtained G/SWCNT-S cathode exhibited excellent performance in Li-S batteries with a capacity as high as 650 mAh g(-1) after 100 cycles even at a high current rate of 5 C. Such a novel G/SWCNT hybrid can serve not only as a prototype to shed light on the chemical principle of G/CNT synthesis but also as a platform for their further applications in the area of nanocomposites, heterogeneous catalysis, drug delivery, electrochemical energy storage, and so on.

  3. Computational Nanomechanics of Carbon Nanotubes and Composites

    Science.gov (United States)

    Srivastava, Deepak; Wei, Chenyu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Nanomechanics of individual carbon and boron-nitride nanotubes and their application as reinforcing fibers in polymer composites has been reviewed with interplay of theoretical modeling, computer simulations and experimental observations. The emphasis in this work is on elucidating the multi-length scales of the problems involved, and of different simulation techniques that are needed to address specific characteristics of individual nanotubes and nanotube polymer-matrix interfaces. Classical molecular dynamics simulations are shown to be sufficient to describe the generic behavior such as strength and stiffness modulus but are inadequate to describe elastic limit and nature of plastic buckling at large strength. Quantum molecular dynamics simulations are shown to bring out explicit atomic nature dependent behavior of these nanoscale materials objects that are not accessible either via continuum mechanics based descriptions or through classical molecular dynamics based simulations. As examples, we discus local plastic collapse of carbon nanotubes under axial compression and anisotropic plastic buckling of boron-nitride nanotubes. Dependence of the yield strain on the strain rate is addressed through temperature dependent simulations, a transition-state-theory based model of the strain as a function of strain rate and simulation temperature is presented, and in all cases extensive comparisons are made with experimental observations. Mechanical properties of nanotube-polymer composite materials are simulated with diverse nanotube-polymer interface structures (with van der Waals interaction). The atomistic mechanisms of the interface toughening for optimal load transfer through recycling, high-thermal expansion and diffusion coefficient composite formation above glass transition temperature, and enhancement of Young's modulus on addition of nanotubes to polymer are discussed and compared with experimental observations.

  4. Catalyst design for the growth of highly packed nanotube forests

    Energy Technology Data Exchange (ETDEWEB)

    Esconjauregui, Santiago; Fouquet, Martin; Bayer, Bernhard C.; Robertson, John [Engineering Department, University of Cambridge, CB2 1PZ Cambridge (United Kingdom); Ducati, Caterina [Materials Science Department, University of Cambridge, CB2 3QZ Cambridge (United Kingdom)

    2011-11-15

    We report a technique for the design of high-density catalyst nanoparticles (NPs) which allow the growth of highly packed forests of carbon nanotubes (CNTs). The technique consists of cycles of deposition and annealing of thin metal films, followed by NP immobilisation. This allows a CNT areal density of at least 10{sup 13} cm{sup -2}. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Carbon nanotubes as tips for atomic force microscopy

    Institute of Scientific and Technical Information of China (English)

    国立秋; 徐宗伟; 赵铁强; 赵清亮; 张飞虎; 董申

    2004-01-01

    Ordinary AFM probes' characters prevent the AFM' s application in various scopes. Carbon nanotubes represent ideal AFM probe materials for their higher aspect ratio, larger Young' s modulus, unique chemical structure, and well-defined electronic property. Carbon nanotube AFM probes are obtained by using a new method of attaching carbon nanotubes to the end of ordinary AFM probes, and are then used for doing AFM experiments. These experiments indicated that carbon nanotube probes have higher elastic deformation, higher resolution and higher durability. And it was also found that carbon nanotube probes can accurately reflect the morphology of deep narrow gaps, while ordinary probes can not reflect.

  6. Interfacing carbon nanotubes (CNT) with plants: enhancement of growth, water and ionic nutrient uptake in maize ( Zea mays) and implications for nanoagriculture

    Science.gov (United States)

    Tiwari, D. K.; Dasgupta-Schubert, N.; Villaseñor Cendejas, L. M.; Villegas, J.; Carreto Montoya, L.; Borjas García, S. E.

    2014-06-01

    The application of nano-biotechnology to crop-science/agriculture (`nanoagriculture') is a recent development. While carbon nanotubes (CNTs) have been shown to dramatically improve germination of some comestible plants, deficiencies in consistency of behavior and reproducibility arise, partially from the variability of the CNTs used. In this work, factory-synthesized multi-walled-CNTs (MWCNTs) of quality-controlled specifications were seen to enhance the germinative growth of maize seedlings at low concentrations but depress it at higher concentrations. Growth enhancement principally arose through improved water delivery by the MWCNT. Polarized EDXRF spectrometry showed that MWCNTs affect mineral nutrient supply to the seedling through the action of the mutually opposing forces of inflow with water and retention in the medium by the ion-CNT transient-dipole interaction. The effect varied with ion type and MWCNT concentration. The differences of the Fe tissue concentrations when relatively high equimolar Fe2+ or Fe3+ was introduced, implied that the ion-CNT interaction might induce redox changes to the ion. The tissue Ca2+ concentration manifested as the antipode of the Fe2+ concentration indicating a possible cationic exchange in the cell wall matrix. SEM images showed that MWCNTs perforated the black-layer seed-coat that could explain the enhanced water delivery. The absence of perforations with the introduction of FeCl2/FeCl3 reinforces the idea of the modification of MWCNT functionality by the ion-CNT interaction. Overall, in normal media, low dose MWCNTs were seen to be beneficial, improving water absorption, plant biomass and the concentrations of the essential Ca, Fe nutrients, opening a potential for possible future commercial agricultural applications.

  7. Preparation of Carbon Nanotubes from Methane on Ni/Cu/A1 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Renzhong Wei; Fengyi Li; Yan Ju

    2005-01-01

    A series of Ni/Cu/Al catalyst samples were prepared by the co-precipitation method. Carbon nanotubes with large inner diameters are successfully synthesized from methane on Ni/Cu/Al catalyst by adding sodium carbonate. The effects of the copper content and amounts of sodium carbonate on the morphology and microstructures of carbon nanotubes were investigated by CO adsorption and TEM technique. The experimental results showed that copper can influence both the catalytic activity and catalyst life. Best result was obtained when the copper content was 15%. Addition of sodium carbonate favors the formation of carbon nanotubes with large inner diameters. The growth mechanism of carbon nanotubes with large inner diameter is discussed.

  8. The fabrication of carbon-nanotube-coated electrodes and a field-emission-based luminescent device.

    Science.gov (United States)

    Agarwal, Sanjay; Yamini Sarada, B; Kar, Kamal K

    2010-02-10

    Tungsten substrates were coated with an Ni or Ni-Co catalyst by the electroless dip coating technique. Various carbon nanotubes were synthesized by the catalytic chemical vapor deposition (CVD) method under different growth conditions. It was observed that Ni-and Ni-Co-coated tungsten substrates give very good growth of carbon nanotubes (CNT) in terms of yield, uniformity and alignment at a growth temperature of 600 degrees C. We fabricated a field-emission-based luminescent light bulb where a tungsten wire coated with carbon nanotubes served as a cathode. Results show lower threshold voltage, better emission stability and higher luminescence for CNT cathodes in comparison with uncoated tungsten cathodes. We found that aligned-coiled carbon nanotubes are superior to straight CNTs in terms of field emission characteristics and luminescence properties. PMID:20057034

  9. Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-03-01

    Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

  10. Carbon nanotube stationary phases for microchip electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Bøggild, Peter; Kutter, Jörg Peter

    nanotubes are very interesting for integration in especially microfluidic devices, because they can readily be grown on planar substrates by means of chemical vapour deposition. In this way the cumbersome process of packing of the stationary phase in the finished microfluidic channels is avoided and the CNT...... surface can furthermore be used directly as a stationary phase in reverse-phase separations, thereby avoiding subsequent functionalization of the nanostructures. This significantly reduces the fabrication time and possibly also increases the reproducibility of the column performance. In this presentation......, microfluidic devices with microfabricated carbon nanotube columns for electrochromatographic separations will be presented. The electrically conductive carbon nanotube layer has been patterned into hexoganol micropillars in order to support electroosmotic flow without forming gas bubbles from electrolysis...

  11. Water Boiling inside Carbon Nanotubes: Towards Efficient Drug Release

    OpenAIRE

    Chaban, Vitaly V.; Prezhdo, Oleg V.

    2012-01-01

    We show using molecular dynamics simulation that spatial confinement of water inside carbon nanotubes (CNT) substantially increases its boiling temperature and that a small temperature growth above the boiling point dramatically raises the inside pressure. Capillary theory successfully predicts the boiling point elevation down to 2 nm, below which large deviations between the theory and atomistic simulation take place. Water behaves qualitatively different inside narrow CNTs, exhibiting trans...

  12. Origin of structural defects in multiwall carbon nanotube

    OpenAIRE

    Hembram, K.P.S.S.; Rao, G. Mohan

    2012-01-01

    We investigate the walls of the defective multiwall carbon nanotube (MWCNT), and give possible mechanism for the formation of defective structure. A generalized model has been proposed for the MWCNT. which consists of (a) catalyst part, (b) embryo part and (c) full grown part. We claim that the weak embryo portion of the MWCNT, is structurally undeveloped. The stress due to pressure imbalance between inside and outside of the MWCNT during growth along with axial load at the embryo portion cau...

  13. The Control of Electron Transport Related Defects in In Situ Fabricated Single Wall Carbon Nanotube Devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhixian [ORNL; Jin, Rongying [ORNL; Eres, Gyula [ORNL; Subedi, Alaska P [ORNL; Mandrus, David [ORNL

    2006-01-01

    Metallic single wall carbon nanotube devices were characterized using low temperature transport measurements to study how the growth conditions affect defect formation in carbon nanotubes. Suspended carbon nanotube devices were grown in situ by a molecular beam growth method on a pair of catalyst islands located on opposing Au electrodes fabricated by electron beam lithography. The authors present experimental evidence that defect formation in carbon nanotubes, in addition to the well known growth temperature dependence, is also affected by the nature and the composition of the carbon growth gases.

  14. Structure Stability of Ⅰ-Type Carbon Nanotube Junctions

    Institute of Scientific and Technical Information of China (English)

    夏丹; 袁喆; 李家明

    2002-01-01

    Carbon nanotubes with junctions may play an important role in future ‘nanoelectronics' and future ‘nano devices'.In particular, junctions constructed with metal and semiconducting nanotubes have potential applications. Basedon the orthogonal tight-binding molecular dynamics method, we present our study of the structure stability ofI-type carbon nanotube junctions.

  15. Deconvoluting hepatic processing of carbon nanotubes.

    Science.gov (United States)

    Alidori, Simone; Bowman, Robert L; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L J; Ulmert, Hans David S; Brea, Elliott J; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A; McDevitt, Michael R

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  16. Making junctions between carbon nanotubes using an ion beam

    CERN Document Server

    Krasheninnikov, A V; Keinonen, J; Banhart, F

    2003-01-01

    Making use of empirical potential molecular dynamics, we study ion bombardment of crossed single-walled carbon nanotubes as a tool to join the nanotubes. We demonstrate that ion irradiation should result in welding of crossed nanotubes, both suspended and deposited on substrates. We further predict optimum ion doses and energies for ion-mediated nanotube welding which may potentially be used for developing complicated networks of joined nanotubes.

  17. Field emission properties of the graphenated carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zanin, H., E-mail: hudson.zanin@bristol.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Ceragioli, H.J.; Peterlevitz, A.C.; Baranauskas, Vitor [Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Marciano, F.R.; Lobo, A.O. [Laboratory of Biomedical Nanotechnology/Institute of Research and Development at UNIVAP, Av. Shishima Hifumi, 2911, CEP 12244-000 Sao Jose dos Campos, SP (Brazil)

    2015-01-01

    Graphical abstract: - Highlights: • Facile method to prepare graphenated carbon nanotubes (g-CNTs). • The electric field emission behaviour of g-CNTs was studied. • g-CNTs show better emission current stability than non-graphenated CNTs. - Abstract: Reduced graphene oxide-coated carbon nanotubes (RGO-CNT) electrodes have been prepared by hot filament chemical vapour deposition system in one-step growth process. We studied RGO-CNT electrodes behaviour as cold cathode in field emission test. Our results show that RGO-CNT retain the low threshold voltage typical of CNTs, but with greatly improved emission current stability. The field emission enhancement value is significantly higher than that expected being caused by geometric effect (height divided by the radius of nanotube). This suggested that the field emission of this hybrid structure is not only from a single tip, but eventually it is from several tips with contribution of graphene nanosheets at CNT's walls. This phenomenon explains why the graphenated carbon nanotubes do not burn out as quickly as CNT does until emission ceases completely. These preliminaries results make nanocarbon materials good candidates for applications as electron sources for several devices.

  18. Advanced materials based on carbon nanotube arrays, yarns and papers

    Science.gov (United States)

    Bradford, Phlip David

    Carbon nanotubes have hundreds of potential applications but require innovative processing techniques to manipulate the microscopic carbon dust into useful devices and products. This thesis describes efforts to process carbon nanotubes (CNTs) using novel methods with the goals of: (1) improving the properties of energy absorbing and composite carbon nanotube materials and (2) increasing understanding of fundamental structure-property relationships within these materials. Millimeter long CNTs, in the form of arrays, yarns and papers, were used to produce energy absorbing foams and high volume fraction CNT composites. Vertically aligned CNT arrays were grown on silicon substrates using chemical vapor deposition (CVD) of ethylene gas over iron nano-particles. The low density, millimeter thick arrays were tested under compression as energy absorbing foams. With additional CVD processing steps, it was possible to tune the compressive properties of the arrays. After the longest treatment, the compressive strength of the arrays was increased by a factor of 35 with a density increase of only six fold, while also imparting recovery from compression to the array. Microscopy revealed that the post-synthesis CVD treatment increased the number of CNT walls through an epitaxial type radial growth on the surface of the as-grown tubes. The increase in tube radius and mutual support between nanotubes explained the increases in compressive strength while an increase in nanotube roughness was proposed as the morphological change responsible for recovery in the array. Carbon nanotube yarns were used as the raw material for macroscopic textile preforms with a multi-level hierarchical carbon nanotube (CNT) structure: nanotubes, bundles, spun single yarns, plied yarns and 3-D braids. In prior tensile tests, composites produced from the 3-D braids exhibited unusual mechanical behavior effects. The proposed physical hypotheses explained those effects by molecular level interactions and

  19. Chiral Anomaly in Toroidal Carbon Nanotubes

    OpenAIRE

    Sasaki, K.

    2001-01-01

    It is pointed out that the chiral anomaly in 1+1 dimensions should be observed in toroidal carbon nanotubes on a planar geometry with varying magnetic field. We show that the chiral anomaly is closely connected with the persistent current in a one-dimensional metallic ring.

  20. Single electron-ics with carbon nanotubes

    NARCIS (Netherlands)

    Götz, G.T.J.

    2010-01-01

    We experimentally investigate Quantum Dots, formed in Carbon Nanotubes. The first part of this thesis deals with charge sensing on such quantum dots. The charge sensor is a metallic Single-electron-transistor, sensitive to the charge of a single electron on the quantum dot. We use this technique for

  1. Spatially resolved spectroscopy on carbon nanotubes

    NARCIS (Netherlands)

    Janssen, J.W.

    2001-01-01

    Carbon nanotubes are small cylindrical molecules with a typical diameter of 1 nm and lengths of up to micrometers. These intriguing molecules exhibit, depending on the exact atomic structure, either semiconducting or metallic behavior. This makes them ideal candidates for possible future molecular e

  2. Effective models for excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia; Duclos, Pierre; Ricaud, Benjamin

    We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with a Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum is well described by a one-dimensional effective Hamiltonian...

  3. Effective models for excitons in carbon nanotubes

    DEFF Research Database (Denmark)

    Cornean, Horia; Duclos, Pierre; Ricaud, Benjamin

    2007-01-01

    We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with opposite charges and a Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum of their relative motion is well described...

  4. A New Resistance Formulation for Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ji-Huan He

    2008-01-01

    Full Text Available A new resistance formulation for carbon nanotubes is suggested using fractal approach. The new formulation is also valid for other nonmetal conductors including nerve fibers, conductive polymers, and molecular wires. Our theoretical prediction agrees well with experimental observation.

  5. Bioaccumulation and ecotoxicity of carbon nanotubes

    DEFF Research Database (Denmark)

    Jackson, Petra; Jacobsen, Nicklas Raun; Baun, Anders;

    2013-01-01

    Carbon nanotubes (CNT) have numerous industrial applications and may be released to the environment. In the aquatic environment, pristine or functionalized CNT have different dispersion behavior, potentially leading to different risks of exposure along the water column. Data included in this review...

  6. In-line manufacture of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, Nicol Michele; Signorelli, Riccardo; Martini, Fabrizio; Corripio Luna, Oscar Enrique

    2015-04-28

    Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.

  7. Heat Transport in Liquid Polyester Resin with Carbon Nanotubes

    Science.gov (United States)

    Vales-Pinzón, C.; Quiñones-Weiss, G.; Alvarado-Gil, J. J.; Medina-Esquivel, R. A.

    2015-11-01

    Carbon nanotubes represent one of the most important materials in nanoscience and nanotechnology, due to their outstanding structural, mechanical, electrical, and thermal properties. It has been shown that when incorporated in a polymeric matrix, carbon nanotubes can improve its physical properties. In this work, thermal-diffusivity measurements of composite materials, prepared by mixing carbon nanotubes in liquid polyester resin, were performed by means of the thermal-wave resonant cavity. The results show an increase of the thermal diffusivity when the volume fraction of carbon nanotubes grows. It is also shown that this increase depends strongly on the diameter of the nanotubes.

  8. Degradation of multiwall carbon nanotubes by bacteria

    International Nuclear Information System (INIS)

    Understanding the environmental transformation of multiwall carbon nanotubes (MWCNTs) is important to their life cycle assessment and potential environmental impacts. We report that a bacterial community is capable of degrading 14C-labeled MWCNTs into 14CO2 in the presence of an external carbon source via co-metabolism. Multiple intermediate products were detected, and genotypic characterization revealed three possible microbial degraders: Burkholderia kururiensis, Delftia acidovorans, and Stenotrophomonas maltophilia. This result suggests that microbe/MWCNTs interaction may impact the long-term fate of MWCNTs. Highlights: •Mineralization of MWCNTs by a bacterial community was observed. •The mineralization required an external carbon source. •Multiple intermediate products were identified in the MWCNT degrading culture. •Three bacterial species were found likely responsible for MWCNT degradation. -- The 14C-labeled multiwall carbon nanotubes can be degraded to 14CO2 and other byproducts by a bacteria community under natural conditions

  9. Carbon nanotubes for stem cell control

    Directory of Open Access Journals (Sweden)

    David A. Stout

    2012-07-01

    Full Text Available In the past decade, two major advancements have transformed the world of tissue engineering and regenerative medicine—stem cells and carbon nano-dimensional materials. In the past, stem cell therapy seemed like it may present a cure for all medical ailments, but problems arose (i.e., immune system clearance, control of differentiation in the body, etc. that have hindered progress. But, with the synergy of carbon nano-dimensional materials, researchers have been able to overcome these tissue engineering and regenerative medicine obstacles and have begun developing treatments for strokes, bone failure, cardiovascular disease, and many other conditions. Here, we briefly review research involving carbon nanotubes which are relevant to the tissue engineering and regenerative medicine field with a special emphasis on carbon nanotube applications for stem cell delivery, drug delivery applications, and their use as improved medical devices.

  10. Electrochemical production of Sn-filled carbon nanotubes in molten salts

    Institute of Scientific and Technical Information of China (English)

    黄辉; 张文魁; 李美超; 甘永平; 马淳安; 张孝彬

    2004-01-01

    Sn-filled carbon nanotubes(CNTs) were prepared in situ by electrolysis of graphite in molten LiCl/SnCl2mixtures. Transmission electron microscopy(TEM) investigation shows that the as-made products contain abundance of carbon nanotubes and most of them are filled with metal nanoparticles or nanorods. Some nanotubes are even inserted with long continuous nanowires more than several micrometers in length. Selected area electron diffraction(SAED) patterns and energy dispersive X-ray spectroscopy(EDS) of the filled nanotubes confirm the presence ofSn inside the nanotubes. The encapsulated Sn was further identified asβ-Sn with tetragonal structure. Based on theexperimental results, a possible growth mechanism of the Sn-filled nanotubes was also discussed.

  11. Preparation of double-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    JIANG Bin; WEI Jinquan; CI Lijie; WU Dehai

    2004-01-01

    Double-walled carbon nanotubes were prepared using the floating chemical vapor deposition with methane as carbon source and adding small amount of sulfur into the ferrocene catalyst. The optimized technological parameters are: the reaction temperature is 1200℃; the catalyst vapor temperature is 80℃; the flow rate of argon is 2000 SCCM; the flow rate of methane is 5 SCCM. The purified DWNTs under these optimized technological parameters have high purity above 90 wt%.

  12. Exploring the Immunotoxicity of Carbon Nanotubes

    Science.gov (United States)

    Yu, Yanmei; Zhang, Qiu; Mu, Qingxin; Zhang, Bin; Yan, Bing

    2008-08-01

    Mass production of carbon nanotubes (CNTs) and their applications in nanomedicine lead to the increased exposure risk of nanomaterials to human beings. Although reports on toxicity of nanomaterials are rapidly growing, there is still a lack of knowledge on the potential toxicity of such materials to immune systems. This article reviews some existing studies assessing carbon nanotubes’ toxicity to immune system and provides the potential mechanistic explanation.

  13. Controlled carbon nanotube synthesis for quantification of polymer-nanotube composite micromechanics

    Science.gov (United States)

    Bult, Justin Bernard

    Conventional experimental approaches to the understanding of nanotube-polymer micro-mechanics have struggled to produce reproducible data due to the inherent difficulty in physically manipulating the nanotube in-situ. To avoid the problems scale represents in nanotube-polymer composites a novel approach of using Polarized Raman spectroscopy was developed. The Raman spectroscopic technique has the advantage of using non-invasive analysis to compute the composite micro mechanical properties of interfacial shear stress and critical length. Composites with nanotubes of defined length were needed in order to use the Raman technique. To satisfy this requirement a new thermal Chemical Vapor Deposition (CVD) tool capable of reproducibly growing aligned length uniformity with large mass yield was designed and built. The course of developing these furnace capabilities led to the investigation of nanotube growth mechanics. It is shown herein that a stable passivation barrier is required for nanotube growth. Using X-Ray Photoelectron Spectroscopy (XPS) depth profiling of metal substrate growth conclusively shows the presence of a stable catalyst layer on the outer surface of stable oxides of greater than 100 nm. By analyzing the diffusion profile represented in the XPS data it is shown that a critical thickness for the passivation oxide can be calculated as a function of time and temperature. For the growth parameters used in this study the critical thickness was found to be between 10 nm and 30 nm depending on the diffusivity value used for iron in chromia. This value agrees well with experimental observation. Uniformly grown carbon nanotubes with lengths of 4, 14, 17, 22, 43, 74, and 116 mum were incorporated into a polycarbonate matrix polymer via solvent-antisolvent processing. The nanotube composites of varied length were tested in tensile strain while Raman spectra were taken concurrently to deduce the load transfer to the nanotube due to composite strain. It is found

  14. Excitation transfer and luminescence in porphyrin-carbon nanotube complexes

    CERN Document Server

    Magadur, G; Alain-Rizzo, V; Voisin, C; Roussignol, Ph; Deleporte, E; Delaire, J A

    2007-01-01

    Functionalization of carbon nanotubes with hydrosoluble porphyrins (TPPS) is achieved by "$\\pi$-stacking". The porphyrin/nanotube interaction is studied by means of optical absorption, photoluminescence and photoluminescence excitation spectroscopies. The main absorption line of the porphyrins adsorbed on nanotubes exhibits a 120 meV red shift, which we ascribe to a flattening of the molecule in order to optimize $\\pi-\\pi$ interactions. The porphyrin-nanotube complex shows a strong quenching of the TPPS emission while the photoluminescence intensity of the nanotubes is enhanced when the excitation laser is in resonance with the porphyrin absorption band. This reveals an efficient excitation transfer from the TPPS to the carbon nanotube.

  15. Comparison of Radioimmuno and Carbon Nanotube Field-Effect Transistor Assays for Measuring Insulin-Like Growth Factor-1 in a Preclinical Model of Human Breast Cancer

    Directory of Open Access Journals (Sweden)

    Kim Man S

    2011-09-01

    Full Text Available Abstract Background To realize the promise of personalized medicine, diagnostic instruments used for detecting and measuring biomarkers must become smaller, faster and less expensive. Although most techniques used currently to detect biomarkers are sensitive and specific, many suffer from several disadvantages including their complexity, high cost and long turnaround time. One strategy to overcome these problems is to exploit carbon nanotube (CNT based biosensors, which are sensitive, use inexpensive disposable components and can be easily adapted to current assay protocols. In this study we investigated the applicability of using a CNT field-effect transistor (CNT-FET as a diagnostic instrument for measuring cancer biomarkers in serum using a mouse model of Breast Cancer Susceptibility 1-related breast cancer. Insulin like growth factor-1 (IGF-1 was chosen because it is highly relevant in breast cancer and because measuring serum IGF-1 levels by conventional methods is complicated due to specific IGF-1 serum binding proteins. Findings Our results show that there is good correlation between the two platforms with respect to detecting serum IGF-1. In fact, the CNT-FETs required only one antibody, gave real-time results and required approximately 100-fold less mouse serum than the radioimmunoassay. Conclusions Both IGF-1 radioimmuno and CNT-FET assays gave comparable results. Indeed, the CNT-FET assay was simpler and faster than the radioimmunoassay. Additionally, the low serum sample required by CNT-FETs can be especially advantageous for studies constricted by limited amount of human clinical samples and for mouse studies, since animals often need to be sacrificed to obtain enough serum for biomarker evaluation.

  16. Lithium storage properties of multiwall carbon nanotubes prepared by CVD

    International Nuclear Information System (INIS)

    Full text: Multiwall carbon nanotubes (MWCNTs) were synthesised by chemical vapour deposition (CVD) method using acetylene gas. The XRD pattern of as prepared carbon nanotubes showed that the d002 value is 3.44 Angstroms. The morphology and microstructure of carbon nanotubes were characterized by HRTEM. Most of carbon nanotubes are entangled together to form bundles or ropes. The diameter of the carbon nanotubes is in the range of 10 ∼ 20 nm. There is a small amount of amorphous carbon particles presented in the sample. However, the yield of carbon nanotubes is more than 95%. Electrochemical properties of carbon nanotubes were characterised via a variety of electrochemical testing techniques. The result of CV test showed that the Li insertion potential is quite low, which is very close to O V versus Li+/Li reference electrode, whereas the potential for Li de-intercalation is in the range of 0.2-0.4 V. There exists a slight voltage hysteresis between Li intercalation and Li de-intercalation, which is similar to the other carbonaceous materials. The intensity of redox peaks of carbon nanotubes decrease with scanning cycle, indicating that the reversible Li insertion capacity gradually decreases. The carbon nanotubes electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. Further improvement of Li storage capacity is possible by opening the end of carbon nanotubes to allow lithium insertion into inner graphene sheet of carbon nanotubes. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised by a.c. impedance measurements. It was found that the lithium diffusion coefficient dLi decreases with an increase of Li ion concentration in carbon nanotube host

  17. Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities

    OpenAIRE

    Watahiki, R.; Shimada, T; Zhao, P; Chiashi, S.; Iwamoto, S.; Arakawa, Y; Maruyama, S.; Kato, Y. K.

    2012-01-01

    Photonic crystal nanocavities are used to enhance photoluminescence from single-walled carbon nanotubes. Micelle-encapsulated nanotubes are deposited on nanocavities within Si photonic crystal slabs and confocal microscopy is used to characterize the devices. Photoluminescence spectra and images reveal nanotube emission coupled to nanocavity modes. The cavity modes can be tuned throughout the emission wavelengths of carbon nanotubes, demonstrating the ability to enhance photoluminescence from...

  18. Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities

    OpenAIRE

    Watahiki, R.; Shimada, T; Zhao, P; Chiashi, S.; Iwamoto, S.; Arakawa, Y; Maruyama, S.; Kato, Y. K.

    2012-01-01

    Photonic crystal nanocavities are used to enhance photoluminescence from single-walled carbon nanotubes. Micelle-encapsulated nanotubes are deposited on nanocavities within Si photonic crystal slabs and confocal microscopy is used to characterize the devices.Photoluminescencespectra and images reveal nanotube emission coupled to nanocavity modes. The cavity modes can be tuned throughout the emission wavelengths of carbon nanotubes, demonstrating the ability to enhance photoluminescence from a...

  19. Nonlinear Optical Properties of Carbon Nanotube Hybrids in Polymer Dispersions

    OpenAIRE

    Wang, Jun; Liao, Kang-Shyang; Früchtl, Daniel; Tian, Ying; Gilchrist, Aisling, , T; Alley, Nigel; Andreoli, Enrico; Aitchison, Brad; Nasibulin, Albert; Byrne, Hugh; Kauppinen, Esko I.; Zhang, Long; Blau, Werner; Curran, Seamus

    2012-01-01

    A series of double-walled carbon nanotubes (DWNTs) and multi-walled nanotubes (MWNTs) functionalized with selected organic chromophores, fluorescein 5(6)-isothiocyanate (FITC), rhodamine B isothiocyanate (RITC) and fullerene (C60) were synthesized by covalently linking these electron-donor groups to the metallic nanotubes. These versatile carbon nanotube composites show remarkable nonlinear optical (NLO) performance, due to a merged effect of the complementary NLO characteristics of the moiet...

  20. Mechanical properties of carbon nanotube/polymer composites

    OpenAIRE

    B. Arash; Wang, Q.(The University of Kansas, Lawrence, USA); Varadan, V. K.

    2014-01-01

    The remarkable mechanical properties of carbon nanotubes, such as high elastic modulus and tensile strength, make them the most ideal and promising reinforcements in substantially enhancing the mechanical properties of resulting polymer/carbon nanotube composites. It is acknowledged that the mechanical properties of the composites are significantly influenced by interfacial interactions between nanotubes and polymer matrices. The current challenge of the application of nanotubes in the compos...

  1. Carbon nanotubes on a spider silk scaffold

    Science.gov (United States)

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-09-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  2. Production of Carbon Nanotubes over Pre-reduced LaCoO3 by Using Fluidized-bed Catalytic Reactor

    Institute of Scientific and Technical Information of China (English)

    刘宝春; 唐水花; 梁奇; 高利珍; 张伯兰; 瞿美臻; 于作龙

    2001-01-01

    A technique has been developed to grow carbon nanotubes by flowing acetylene over pre-reduced LaCoO3 catalyst in a fluidized- bed catalytic reactor. Carbon nanotubes were characterized by means of SEM and TEM. The pre-reduced LaCoO3catalyst was found to be effective in producing carbon nanotubes with even diameter. The effects of reduction temperature of LaCoO3 on the growth of carbon nanotubes were investigated. This process can easily be scaled up.

  3. Analytical modeling of glucose biosensors based on carbon nanotubes

    OpenAIRE

    Pourasl, Ali H; Ahmadi, Mohammad Taghi; Rahmani, Meisam; Chin, Huei Chaeng; Lim, Cheng Siong; Ismail, Razali; Tan, Michael Loong Peng

    2014-01-01

    In recent years, carbon nanotubes have received widespread attention as promising carbon-based nanoelectronic devices. Due to their exceptional physical, chemical, and electrical properties, namely a high surface-to-volume ratio, their enhanced electron transfer properties, and their high thermal conductivity, carbon nanotubes can be used effectively as electrochemical sensors. The integration of carbon nanotubes with a functional group provides a good and solid support for the immobilization...

  4. A new method of preparing single-walled carbon nanotubes

    OpenAIRE

    Vivekchang, SRC; Govindaraj, A.

    2003-01-01

    A novel method of purification for single-walled carbon nanotubes, prepared by an arc-discharge method, is described. The method involves a combination of acid washing followed by high temperature hydrogen treatment to remove the metal nanoparticles and amorphous carbon present in the as-synthesized single-walled carbon nanotubes. The purified single-walled carbon nanotubes have been characterised by low-angle X-ray diffraction, electron microscopy, thermo-gravimetric analysis and Raman spect...

  5. A new method of preparing single-walled carbon nanotubes

    Indian Academy of Sciences (India)

    S R C Vivekchand; A Govindaraj

    2003-10-01

    A novel method of purification for single-walled carbon nanotubes, prepared by an arc-discharge method, is described. The method involves a combination of acid washing followed by high temperature hydrogen treatment to remove the metal nanoparticles and amorphous carbon present in the as-synthesized singlewalled carbon nanotubes. The purified single-walled carbon nanotubes have been characterised by low-angle X-ray diffraction, electron microscopy, thermo-gravimetric analysis and Raman spectroscopy.

  6. Functionalization of vertically aligned carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Eloise Van Hooijdonk

    2013-02-01

    Full Text Available This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs. The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs.

  7. Optical trapping of carbon nanotubes and graphene

    Directory of Open Access Journals (Sweden)

    S. Vasi

    2011-09-01

    Full Text Available We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

  8. On the Nanoindentation of the Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Petre P. Teodorescu

    2010-01-01

    Full Text Available A new inverse approach is proposed in this paper, which combines elements of nonlocal theory and molecular mechanics, based on the experimental results available in the nanoindentation literature. The effect of the inlayer van der Waals atomistic interactions for carbon nanotubes with multiple walls (MWCNT is included by means of the Brenner-Tersoff potential and experimental results. The neighboring walls of MWCNT are coupled through van der Waals interactions, and the shell buckling would initiate in the outermost shell, when nanotubes are short. The nanoindentation technique is simulated for the axially compressed of individual nanotubes, in order to evaluate the load-unloaded-displacement, the curve critical buckling and the appropriate values for local Lamé constants.

  9. Nanosystems of Polymerized Fullerenes and Carbon Nanotubes

    Science.gov (United States)

    Scharff, Peter; Cui, Shen

    Nanosystems based on polymerized fullerenes and carbon-nanotubes begin to play an important role in the field of nanotechnology. Nanotubes can be used as molecular wires, and can even figure as building elements for molecular electronics. Furthermore nanotubes can be used as amplifiers in composite materials, as a result of their unique mechanical properties. Many other applications, as for example as electron emitters for flat screens, are currently under development. Fullerens are known to be strong electron acceptors, which enables them to support the electron-hole pair separation in polymer based photovoltaic cells. The use of fulleren chains instead of fullerenes could improve the anisotropic electronic conductivity in the contained polymer layer, and therefore enhance their performance.

  10. Mechanical properties of functionalized carbon nanotubes

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) used to reinforce polymer matrix composites are functionalized to form covalent bonds with the polymer in order to enhance the CNT/polymer interfaces. These bonds destroy the perfect atomic structures of a CNT and degrade its mechanical properties. We use atomistic simulations to study the effect of hydrogenization on the mechanical properties of single-wall carbon nanotubes. The elastic modulus of CNTs gradually decreases with the increasing functionalization (percentage of C-H bonds). However, both the strength and ductility drop sharply at a small percentage of functionalization, reflecting their sensitivity to C-H bonds. The cluster C-H bonds forming two rings leads to a significant reduction in the strength and ductility. The effect of carbonization has essentially the same effect as hydrogenization

  11. Purification of Carbon Nanotubes by Proton Irradiation

    Science.gov (United States)

    Kim, Euikwoun; Lee, Jeonggil; Lee, Younman; Jeon, Jaekyun; Kim, Jae-Yong; Kim, Jeongha; Shin, Kwanwoo; Youn, Sang-Pil; Kim, Kyeryung

    2007-10-01

    Carbon nanotubes (CNTs) exhibit variety of superior physical properties including well-defined nanodimensional structure, high electrical and thermal conductivity, and good mechanical stability against external irradiations. Further, a large specific surface area per unit weight suggests that carbon nanotubes could be excellent candidates for gas storage, purification, and separation. However, the practical application of CNTs is limited mainly due to the metallic impurities that were used as a catalyst during the fabrication process. Here, we irradiated CNTs by using high energy proton beams (35.7 MeV at the Bragg Peak). Interestingly, metallic impurities such as Fe, Ni, Co and chunk of amorphous carbon that were attached on the surface of CNTs were completely removed after the irradiation. The mechanism of such the purification process is not understood. The possible speculation will be demonstrated combined with the changes of physical properties including the appearance of the magnetism after the irradiation.

  12. Carbon Nanotubes for Space Photovoltaic Applications

    Science.gov (United States)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

    2007-01-01

    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  13. A Spray Pyrolysis Method to Grow Carbon Nanotubes on Carbon Fibres, Steel and Ceramic Bricks.

    Science.gov (United States)

    Vilatela, Juan J; Rabanal, M E; Cervantes-Sodi, Felipe; García-Ruiz, Máximo; Jiménez-Rodríguez, José A; Reiband, Gerd; Terrones, Mauricio

    2015-04-01

    We demonstrate a spray pyrolysis method to grow carbon nanotubes (CNTs) with high degree of crystallinity, aspect ratio and degree of alignment on a variety of different substrates, such as conventional steel, carbon fibres (CF) and ceramics. The process consists in the chemical vapour deposition of both a thin SiO2 layer and CNTs that subsequently grow on this thin layer. After CNT growth, increases in specific surface by factors of 1000 and 30 for the steel and CF samples, respectively, are observed. CNTs growth on ceramic surfaces results in a surface resistance of 37.5 Ohm/sq. When using conventional steel as a rector tube, we observed CNTs growth rates of 0.6 g/min. Details of nanotube morphology and the growth mechanism are discussed. Since the method discussed here is highly versatile, it opens up a wide variety of applications in which specific substrates could be used in combination with CNTs.

  14. A Spray Pyrolysis Method to Grow Carbon Nanotubes on Carbon Fibres, Steel and Ceramic Bricks.

    Science.gov (United States)

    Vilatela, Juan J; Rabanal, M E; Cervantes-Sodi, Felipe; García-Ruiz, Máximo; Jiménez-Rodríguez, José A; Reiband, Gerd; Terrones, Mauricio

    2015-04-01

    We demonstrate a spray pyrolysis method to grow carbon nanotubes (CNTs) with high degree of crystallinity, aspect ratio and degree of alignment on a variety of different substrates, such as conventional steel, carbon fibres (CF) and ceramics. The process consists in the chemical vapour deposition of both a thin SiO2 layer and CNTs that subsequently grow on this thin layer. After CNT growth, increases in specific surface by factors of 1000 and 30 for the steel and CF samples, respectively, are observed. CNTs growth on ceramic surfaces results in a surface resistance of 37.5 Ohm/sq. When using conventional steel as a rector tube, we observed CNTs growth rates of 0.6 g/min. Details of nanotube morphology and the growth mechanism are discussed. Since the method discussed here is highly versatile, it opens up a wide variety of applications in which specific substrates could be used in combination with CNTs. PMID:26353505

  15. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    Science.gov (United States)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  16. Remote Joule heating by a carbon nanotube

    Science.gov (United States)

    Baloch, Kamal H.; Voskanian, Norvik; Bronsgeest, Merijntje; Cumings, John

    2012-05-01

    Minimizing Joule heating remains an important goal in the design of electronic devices. The prevailing model of Joule heating relies on a simple semiclassical picture in which electrons collide with the atoms of a conductor, generating heat locally and only in regions of non-zero current density, and this model has been supported by most experiments. Recently, however, it has been predicted that electric currents in graphene and carbon nanotubes can couple to the vibrational modes of a neighbouring material, heating it remotely. Here, we use in situ electron thermal microscopy to detect the remote Joule heating of a silicon nitride substrate by a single multiwalled carbon nanotube. At least 84% of the electrical power supplied to the nanotube is dissipated directly into the substrate, rather than in the nanotube itself. Although it has different physical origins, this phenomenon is reminiscent of induction heating or microwave dielectric heating. Such an ability to dissipate waste energy remotely could lead to improved thermal management in electronic devices.

  17. Developing Carbon Nanotube Standards at NASA

    Science.gov (United States)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

  18. Graphene nanoribbons production from flat carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Melo, W. S.; Guerini, S.; Diniz, E. M., E-mail: eduardo.diniz@ufma.br [Departamento de Física, Universidade Federal do Maranhão, São Luís - MA 65080-805 (Brazil)

    2015-11-14

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons.

  19. Graphene nanoribbons production from flat carbon nanotubes

    International Nuclear Information System (INIS)

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons

  20. Adhesion to carbon nanotube conductive scaffolds forces action-potential appearance in immature rat spinal neurons.

    Science.gov (United States)

    Fabbro, Alessandra; Sucapane, Antonietta; Toma, Francesca Maria; Calura, Enrica; Rizzetto, Lisa; Carrieri, Claudia; Roncaglia, Paola; Martinelli, Valentina; Scaini, Denis; Masten, Lara; Turco, Antonio; Gustincich, Stefano; Prato, Maurizio; Ballerini, Laura

    2013-01-01

    In the last decade, carbon nanotube growth substrates have been used to investigate neurons and neuronal networks formation in vitro when guided by artificial nano-scaled cues. Besides, nanotube-based interfaces are being developed, such as prosthesis for monitoring brain activity. We recently described how carbon nanotube substrates alter the electrophysiological and synaptic responses of hippocampal neurons in culture. This observation highlighted the exceptional ability of this material in interfering with nerve tissue growth. Here we test the hypothesis that carbon nanotube scaffolds promote the development of immature neurons isolated from the neonatal rat spinal cord, and maintained in vitro. To address this issue we performed electrophysiological studies associated to gene expression analysis. Our results indicate that spinal neurons plated on electro-conductive carbon nanotubes show a facilitated development. Spinal neurons anticipate the expression of functional markers of maturation, such as the generation of voltage dependent currents or action potentials. These changes are accompanied by a selective modulation of gene expression, involving neuronal and non-neuronal components. Our microarray experiments suggest that carbon nanotube platforms trigger reparative activities involving microglia, in the absence of reactive gliosis. Hence, future tissue scaffolds blended with conductive nanotubes may be exploited to promote cell differentiation and reparative pathways in neural regeneration strategies.

  1. CARBON NANOTUBES: AN APPROACH TO NOVEL DRUG DELIVERY SYSTEM

    Directory of Open Access Journals (Sweden)

    M. H. Alai et al.

    2012-01-01

    Full Text Available Carbon nanotubes are cylindrical carbon molecules have novel properties, making them potentially useful in many applications in nanotechnology, electronics, optics, and other fields of material science as well as potential uses in architectural fields. They have unique electronic, mechanical, optical and chemical properties that make them good candidates for a wide variety of applications, including drug transporters, new therapeutics, delivery systems and diagnostics. Their unique surface area, stiffness, strength and resilience have led to much excitement in the field of pharmacy. Nanotubes are categorized as single-walled nanotubes, multiple walled nanotubes. Various techniques have been developed to produce nanotubes in sizeable quantities, including arc discharge, laser ablation, chemical vapor deposition. They can pass through membranes, carrying therapeutic drugs, vaccines and nucleic acids deep into the cell to targets previously unreachable. Purification of the tubes can be divided into a couple of main techniques: oxidation, acid treatment, annealing, sonication, filtering and functionalization techniques. The main problem of insolubility in aqueous media has been solved by developing a synthetic protocol that allows highly water-soluble carbon NTs to be obtained. The modifications are done to improve efficiency of carbon nanotubes by formulating luminescent carbon nanotubes, ultrathin carbon nanoneedles, magnetically guided nanotubes. The application of carbon nanotube in tissue engineering, drug carrier release system, wound healing, in cancer treatment and as biosensor. Researchers have recently developed a new approach to Boron Neutron Capture Therapy in the treatment of cancer using substituted Carborane-Appended Water-Soluble single-wall carbon nanotubes.

  2. Thermal Spreading in Carbon Nanotube Coating.

    Science.gov (United States)

    Kim, Duckjong; Shin, Dong-Sig; Yu, Jeonghwan; Kim, Haesik; Kim, Jae-Hyun; Woo, Chang-Su

    2015-11-01

    Carbon nanomaterials, such as carbon nanotubes (CNTs) and graphene, have attracted significant attention as good candidates for next-generation heat-spreading materials because of their high thermal conductivity, mechanical flexibility, etc. Regarding the thermal spreading performance of carbon-based nanofilms, remarkable test results have been reported mainly from the industrial side, but their validity and the physical mechanism underlying the heat transfer enhancement are still under debate. In this study, we assess the thermal spreading performance of a multi-walled CNT film on a copper foil using a non-contact characterization method in a simple and methodical manner, and discuss the possibility of carbon nanofilms as heat spreaders based on the experimental and numerical results. This study provides useful information on heat transfer enhancement by carbon nanofilms and could contribute to the development of high-performance carbon-based heat-spreading coatings. PMID:26726629

  3. Hexagonal silicon nanotube confined inside a carbon nanotube: A first-principles study

    Science.gov (United States)

    Zhu, Weijuan; Yan, Xiaohong; Xiao, Yang

    2008-02-01

    We studied the stability, geometrical structures and electronic energy band of hexagonal silicon nanotube (SiNT) confined inside carbon nanotubes based on first-principle calculations. The results show that the encapsulating process of SiNT is exothermic in ( 9,9) carbon nanotube while endothermic in ( 8,8) and ( 7,7) carbon nanotubes. When the SiNT is inserted into ( 9,9) carbon nanotube, the insertion energy is about 0.09 eV. Energy band of SiNT@( 9,9) nanotube is not distorted greatly compared with the superposition of bands of isolated SiNT and ( 9,9) carbon nanotube. Especially, a parabolic band occurs near the Fermi level of energy band in SiNT@( 7,7) nanotube. Such a band could be a nearly free electronic state originating from carbon nanotube. Moreover, we discuss the variation of total energy as the SiNT rotates around its axis inside carbon nanotubes.

  4. Buckling-driven delamination of carbon nanotube forests

    Science.gov (United States)

    Pour Shahid Saeed Abadi, Parisa; Hutchens, Shelby B.; Greer, Julia R.; Cola, Baratunde A.; Graham, Samuel

    2013-06-01

    We report buckling-driven delamination of carbon nanotube (CNT) forests from their growth substrates when subjected to compression. Macroscale compression experiments reveal local delamination at the CNT forest-substrate interface. Results of microscale flat punch indentations indicate that enhanced CNT interlocking at the top surface of the forest accomplished by application of a metal coating causes delamination of the forest from the growth substrate, a phenomenon not observed in indentation of as-grown CNT forests. We postulate that the post-buckling tensile stresses that develop at the base of the CNT forests serve as the driving force for delamination.

  5. Carbon Nanotube Composites for Electronic Packaging Applications: A Review

    OpenAIRE

    Lavanya Aryasomayajula; Klaus-Juergen Wolter

    2013-01-01

    Composite engineering comprises of metal matrix composites. They have high strength-weight ratio, better stiffness, economical production, and ease of availability of raw materials. The discovery of carbon nanotubes has opened new possibilities to face challenges better. Carbon Nanotubes are known for their high mechanical strength, excellent thermal and electrical properties. Recent research has made progress in fabricating carbon nanotube metal matrix and polymer-based composites. The metho...

  6. Thermogravimetric Analysis of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

    2010-01-01

    An improved protocol for thermogravimetric analysis (TGA) of samples of single-wall carbon nanotube (SWCNT) material has been developed to increase the degree of consistency among results so that meaningful comparisons can be made among different samples. This improved TGA protocol is suitable for incorporation into the protocol for characterization of carbon nanotube material. In most cases, TGA of carbon nanotube materials is performed in gas mixtures that contain oxygen at various concentrations. The improved protocol is summarized.

  7. A statistical mechanics model of carbon nanotube macro-films

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Carbon nanotube macro-films are two-dimensional films with micrometer thickness and centimeter by centimeter in-plane dimension.These carbon nanotube macroscopic assemblies have attracted significant attention from the material and mechanics communities recently because they can be easily handled and tailored to meet specific engineering needs.This paper reports the experimental methods on the preparation and characterization of single-walled carbon nanotube macro-films,and a statistical mechanics model on ...

  8. Varied morphology carbon nanotubes and method for their manufacture

    Science.gov (United States)

    Li, Wenzhi; Wen, Jian Guo; Ren, Zhi Feng

    2007-01-02

    The present invention describes the preparation of carbon nanotubes of varied morphology, catalyst materials for their synthesis. The present invention also describes reactor apparatus and methods of optimizing and controlling process parameters for the manufacture carbon nanotubes with pre-determined morphologies in relatively high purity and in high yields. In particular, the present invention provides methods for the preparation of non-aligned carbon nanotubes with controllable morphologies, catalyst materials and methods for their manufacture.

  9. Nanoscale fluid transportation through individual carbon nanotubes

    Science.gov (United States)

    He, Jin; Cao, Di; Pang, Pei; Luo, Tao; Lindsay, Stuart; Kristic, Predrag; Nuckolls, Colin

    2011-03-01

    There are great interest in both simulation and experiment of fluid flow on the nanoscale. Carbon nanotubes, with their extremely small inner diameter (usually below 2 nm) and atomic smooth inner surface, are ideal materials for studying nanoconfinement and ion and molecule nanoscale translocation. The excellent electrical properties of CNTs can also be integrated to achieve nanoelectrofluidic device. This presentation describes our recent progress in studying fluid transport through individual carbon nanotubes, including simultaneously ionic and electronic measurements during water, ion and molecule translocation. This work was supported by the DNA Sequencing Technology Program of the National Human Genome Research Institute (1RC2HG005625-01, 1R21HG004770-01).

  10. Carbon Nanotube Flexible and Stretchable Electronics.

    Science.gov (United States)

    Cai, Le; Wang, Chuan

    2015-12-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  11. Advanced technology for functionalization of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Lingjie Meng; Chuanlong Fu; Qinghua Lu

    2009-01-01

    Functionalization of carbon nanotubes (CNTs) has attracted considerable interest in the fields of physics, chemistry, material science and biology. The functionalized CNTs exhibit improved properties enabling facile fabrication of novel nanomaterials and nanodevices. Most of the functionalization approaches developed at present could be categorized into the covalent attachment of functional groups and the non-covalent adsorption of various functional molecules onto the surface of CNTs. This review highlights recent development and our work in functionalization of carbon nanotubes, leading to bio-compatible CNTs, fluorescent CNTs and transition metal func-tionalizcd CNTs. These novel methods possess advantages such as simplified technical procedures and reduced cost of novel nanoma-terials and nanodcvices fabrication.

  12. Carbon Nanotube Flexible and Stretchable Electronics

    Science.gov (United States)

    Cai, Le; Wang, Chuan

    2015-08-01

    The low-cost and large-area manufacturing of flexible and stretchable electronics using printing processes could radically change people's perspectives on electronics and substantially expand the spectrum of potential applications. Examples range from personalized wearable electronics to large-area smart wallpapers and from interactive bio-inspired robots to implantable health/medical apparatus. Owing to its one-dimensional structure and superior electrical property, carbon nanotube is one of the most promising material platforms for flexible and stretchable electronics. Here in this paper, we review the recent progress in this field. Applications of single-wall carbon nanotube networks as channel semiconductor in flexible thin-film transistors and integrated circuits, as stretchable conductors in various sensors, and as channel material in stretchable transistors will be discussed. Lastly, state-of-the-art advancement on printing process, which is ideal for large-scale fabrication of flexible and stretchable electronics, will also be reviewed in detail.

  13. Density controlled carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng F.; Tu, Yi

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  14. Printed Carbon Nanotube Electronics and Sensor Systems.

    Science.gov (United States)

    Chen, Kevin; Gao, Wei; Emaminejad, Sam; Kiriya, Daisuke; Ota, Hiroki; Nyein, Hnin Yin Yin; Takei, Kuniharu; Javey, Ali

    2016-06-01

    Printing technologies offer large-area, high-throughput production capabilities for electronics and sensors on mechanically flexible substrates that can conformally cover different surfaces. These capabilities enable a wide range of new applications such as low-cost disposable electronics for health monitoring and wearables, extremely large format electronic displays, interactive wallpapers, and sensing arrays. Solution-processed carbon nanotubes have been shown to be a promising candidate for such printing processes, offering stable devices with high performance. Here, recent progress made in printed carbon nanotube electronics is discussed in terms of materials, processing, devices, and applications. Research challenges and opportunities moving forward from processing and system-level integration points of view are also discussed for enabling practical applications.

  15. Carbon nanotube based stationary phases for microchip chromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kutter, Jörg Peter

    2012-01-01

    The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have...

  16. A Carbon Nanotube Cable for a Space Elevator

    Science.gov (United States)

    Bochnícek, Zdenek

    2013-01-01

    In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are…

  17. Electrostatic sensing and electrochemistry with single carbon nanotubes

    NARCIS (Netherlands)

    Heller, I.

    2009-01-01

    This thesis describes the experimental study of devices based on single carbon nanotubes in the context of (bio)sensing in aqueous solutions. Carbon nanotubes are cylindrical molecules of sp2- carbon, about one nanometer in diameter and typically several micrometers long, which have semiconducting o

  18. Spontaneous exciton dissociation in carbon nanotubes

    OpenAIRE

    Kumamoto, Y.; Yoshida, M.; Ishii, A; Yokoyama, A.; Shimada, T; Kato, Y. K.

    2013-01-01

    Simultaneous photoluminescence and photocurrent measurements on individual single-walled carbon nanotubes reveal spontaneous dissociation of excitons into free electron-hole pairs. Correlation of luminescence intensity and photocurrent shows that a significant fraction of excitons are dissociating during their relaxation into the lowest exciton state. Furthermore, the combination of optical and electrical signals also allows for extraction of the absorption cross section and the oscillator st...

  19. On the Nanoindentation of the Carbon Nanotubes

    OpenAIRE

    Petre P.Teodorescu; Veturia Chiroiu; Ligia Munteanu; Valeria Moşneguţu

    2010-01-01

    A new inverse approach is proposed in this paper, which combines elements of nonlocal theory and molecular mechanics, based on the experimental results available in the nanoindentation literature. The effect of the inlayer van der Waals atomistic interactions for carbon nanotubes with multiple walls (MWCNT) is included by means of the Brenner-Tersoff potential and experimental results. The neighboring walls of MWCNT are coupled through van der Waals interactions, and the shell buckling would ...

  20. Magnetic Carbon Nanotubes for Protein Separation

    OpenAIRE

    Xiaobin Fan; Fengbao Zhang; Guoliang Zhang; Xiuhui Diao; Hongyu Chen

    2012-01-01

    Magnetic separation is a promising strategy in protein separation. Owing to their unique one-dimensional structures and desired magnetic properties, stacked-cup carbon nanotubes (CSCNTs) with magnetic nanoparticles trapped in their tips can serve as train-like systems for protein separation. In this study, we functionalized the magnetic CSCNTs with high density of carboxyl groups by radical addition and then anchored 3-aminophenylboronic acid (APBA) through amidation reaction to achieve orien...

  1. Bio-inspired Hybrid Carbon Nanotube Muscles

    OpenAIRE

    Tae Hyeob Kim; Cheong Hoon Kwon; Changsun Lee; Jieun An; Tam Thi Thanh Phuong; Sun Hwa Park; Lima, Márcio D.; Baughman, Ray H.; Tong Mook Kang; Seon Jeong Kim

    2016-01-01

    There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with p...

  2. Composites with polymer-grafted carbon nanotubes

    OpenAIRE

    Paiva, M. C.; Novais, R. M.; Covas, J. A.

    2014-01-01

    Carbon nanotube (CNT)/polymer composites exhibit the processability advantages of plastics, while conveying electrical conductivity characteristics suitable for electric transport, or for sensing functionalities. The success of their application depends on the ability to homogeneously disperse the CNT in the polymer matrices to form a stable conductive network. The structural strength of the nanocomposite is also desirable, and may be a requirement. The chemical functionalization of the CNT i...

  3. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    OpenAIRE

    Wei Wang(College of William and Mary); Yuhe Zhu; Susan Liao; Jiajia Li

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matr...

  4. Aqueous solution dispersement of carbon nanotubes

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  5. Carbon nanotube-polymer nanocomposite infrared sensor.

    Science.gov (United States)

    Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

    2008-04-01

    The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites. PMID:18333623

  6. Carbon nanotubes: artificial nanomaterials to engineer single neurons and neuronal networks.

    Science.gov (United States)

    Fabbro, Alessandra; Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

    2012-08-15

    In the past decade, nanotechnology applications to the nervous system have often involved the study and the use of novel nanomaterials to improve the diagnosis and therapy of neurological diseases. In the field of nanomedicine, carbon nanotubes are evaluated as promising materials for diverse therapeutic and diagnostic applications. Besides, carbon nanotubes are increasingly employed in basic neuroscience approaches, and they have been used in the design of neuronal interfaces or in that of scaffolds promoting neuronal growth in vitro. Ultimately, carbon nanotubes are thought to hold the potential for the development of innovative neurological implants. In this framework, it is particularly relevant to document the impact of interfacing such materials with nerve cells. Carbon nanotubes were shown, when modified with biologically active compounds or functionalized in order to alter their charge, to affect neurite outgrowth and branching. Notably, purified carbon nanotubes used as scaffolds can promote the formation of nanotube-neuron hybrid networks, able per se to affect neuron integrative abilities, network connectivity, and synaptic plasticity. We focus this review on our work over several years directed to investigate the ability of carbon nanotube platforms in providing a new tool for nongenetic manipulations of neuronal performance and network signaling. PMID:22896805

  7. Carbon nanotubes: artificial nanomaterials to engineer single neurons and neuronal networks.

    Science.gov (United States)

    Fabbro, Alessandra; Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

    2012-08-15

    In the past decade, nanotechnology applications to the nervous system have often involved the study and the use of novel nanomaterials to improve the diagnosis and therapy of neurological diseases. In the field of nanomedicine, carbon nanotubes are evaluated as promising materials for diverse therapeutic and diagnostic applications. Besides, carbon nanotubes are increasingly employed in basic neuroscience approaches, and they have been used in the design of neuronal interfaces or in that of scaffolds promoting neuronal growth in vitro. Ultimately, carbon nanotubes are thought to hold the potential for the development of innovative neurological implants. In this framework, it is particularly relevant to document the impact of interfacing such materials with nerve cells. Carbon nanotubes were shown, when modified with biologically active compounds or functionalized in order to alter their charge, to affect neurite outgrowth and branching. Notably, purified carbon nanotubes used as scaffolds can promote the formation of nanotube-neuron hybrid networks, able per se to affect neuron integrative abilities, network connectivity, and synaptic plasticity. We focus this review on our work over several years directed to investigate the ability of carbon nanotube platforms in providing a new tool for nongenetic manipulations of neuronal performance and network signaling.

  8. Carbon nanotubes from synthesis to in vivo biomedical applications.

    Science.gov (United States)

    Sajid, Muhammad Imran; Jamshaid, Usama; Jamshaid, Talha; Zafar, Nadiah; Fessi, H; Elaissari, Abdelhamid

    2016-03-30

    Owing to their unique and interesting properties, extensive research round the globe has been carried out on carbon nanotubes and carbon nanotubes based systems to investigate their practical usefulness in biomedical applications. The results from these studies demonstrate a great promise in their use in targeted drug delivery systems, diagnostic techniques and in bio-analytical applications. Although, carbon nanotubes possess quite interesting properties, which make them potential candidates in the biomedical science, but they also have some inherent properties which arise great concern regarding their biosafety. In this comprehensive review, we have discussed different aspects of carbon nanotubes and carbon nanotube based systems related to biomedical applications. In the beginning, a short historical account of these tiny yet powerful particles is given followed by discussion regarding their types, properties, methods of synthesis, large scale production method, purification techniques and characterization aspects of carbon nanotubes. In the second part of the review, the functionalization of carbon nanotubes is reviewed in detail, which is not only important to make them biocompatible and stable in biological systems but also render them a great property of loading various biomolecules, diagnostic and therapeutic moieties resulting in diversified applications. In the final part of the review, emphasis is given on the pharmacokinetic aspects of carbon nanotubes including administration routes, absorption mechanisms, distribution and elimination of carbon nanotubes based systems. Lastly, a comprehensive account about the potential biomedical applications has been given followed by insights into the future.

  9. Carbon nanotube materials for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J. [National Renewable Energy Lab., Golden, CO (United States)

    1998-08-01

    Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

  10. Fast Electromechanical Switches Based on Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama; Wong, Eric; Epp, Larry

    2008-01-01

    Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma

  11. Ferroelectric–carbon nanotube memory devices

    International Nuclear Information System (INIS)

    One-dimensional ferroelectric nanostructures, carbon nanotubes (CNT) and CNT–inorganic oxides have recently been studied due to their potential applications for microelectronics. Here, we report coating of a registered array of aligned multi-wall carbon nanotubes (MWCNT) grown on silicon substrates by functional ferroelectric Pb(Zr,Ti)O3 (PZT) which produces structures suitable for commercial prototype memories. Microstructural analysis reveals the crystalline nature of PZT with small nanocrystals aligned in different directions. First-order Raman modes of MWCNT and PZT/MWCNT/n-Si show the high structural quality of CNT before and after PZT deposition at elevated temperature. PZT exists mostly in the monoclinic Cc/Cm phase, which is the origin of the high piezoelectric response in the system. Low–loss square piezoelectric hysteresis obtained for the 3D bottom-up structure confirms the switchability of the device. Current–voltage mapping of the device by conducting atomic force microscopy (c-AFM) indicates very low transient current. Fabrication and functional properties of these hybrid ferroelectric–carbon nanotubes is the first step towards miniaturization for future nanotechnology sensors, actuators, transducers and memory devices. (paper)

  12. Carbon Nanotube Paper-Based Electroanalytical Devices

    Directory of Open Access Journals (Sweden)

    Youngmi Koo

    2016-04-01

    Full Text Available Here, we report on carbon nanotube paper-based electroanalytical devices. A highly aligned-carbon nanotube (HA-CNT array, grown using chemical vapor deposition (CVD, was processed to form bi-layered paper with an integrated cellulose-based Origami-chip as the electroanalytical device. We used an inverse-ordered fabrication method from a thick carbon nanotube (CNT sheet to a thin CNT sheet. A 200-layered HA-CNT sheet and a 100-layered HA-CNT sheet are explored as a working electrode. The device was fabricated using the following methods: (1 cellulose-based paper was patterned using a wax printer, (2 electrical connection was made using a silver ink-based circuit printer, and (3 three electrodes were stacked on a 2D Origami cell. Electrochemical behavior was evaluated using electrochemical impedance spectroscopy (EIS and cyclic voltammetry (CV. We believe that this platform could attract a great deal of interest for use in various chemical and biomedical applications.

  13. Fluoride and lead adsorption on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    WANG Shuguang; LI Yanhui

    2004-01-01

    The properties and applications of CNT have been studied extensively since Iijima discovered them in 1991[1,2]. They have exceptional mechanical properties and unique electrical property, highly chemical stability and large specific surface area. Thus far, they have widely potential applications in many fields. They can be used as reinforcing materials in composites[3], field emissions[4], hydrogen storage[5], nanoelectronic components[6], catalyst supports[7], adsorption material and so on. However, the study on the potential application of CNT, environmental protection field in particular, was hardly begun.Long[8] et al. reported that CNT had a significantly higher dioxin removal efficiency than that of activated carbon. The Langmuir adsorption constant is 2.7 × 1052, 1.3 × 1018 respectively. The results indicated that CNT is potential candidate for the removal of micro-organic pollutants. However, the reports on the CNT used as fluoride and heavy metal adsorbent are seldom.In this paper, A novel material, alumina supported on carbon nanotubes (Al2O3/CNT), was prepared from carbon nanotubes and Al(NO3)3. X-ray diffraction (XRD) spectra demonstrate that alumina is amorphous, and scanning electron microscope (SEM) images show that CNT and alumina are homogeneously mixed. Furthermore, the fluoride adsorption behavior on the surface of Al2O3/CNT has been investigated and compared with other adsorbents. The results indicate that Al2O3/CNT has a high adsorption capacity, with a saturation adsorption capacity of 39.4 mg/g. It is also found that the adsorption capacity of Al2O3/CNT is 3.0~4.5 times that of γ-Al2O3while almost equal to that of IRA-410 polymeric resin at 25 ℃. The adsorption isotherms of fluoride on Al2O3/CNT is fit the Freundlich equation well, optimal pH ranging from 5.0 to 9.0.Also in this paper, a novel material, modified carbon nanotubes (CNT), was prepared from carbon nanotubes and HNO3 under boiling condition. Infrared spectroscopy (IR

  14. Occupational nanosafety considerations for carbon nanotubes and carbon nanofibers.

    Science.gov (United States)

    Castranova, Vincent; Schulte, Paul A; Zumwalde, Ralph D

    2013-03-19

    Carbon nanotubes (CNTs) are carbon atoms arranged in a crystalline graphene lattice with a tubular morphology. CNTs exhibit high tensile strength, possess unique electrical properties, are durable, and can be functionalized. These properties allow applications as structural materials, in electronics, as heating elements, in batteries, in the production of stain-resistant fabric, for bone grafting and dental implants, and for targeted drug delivery. Carbon nanofibers (CNFs) are strong, flexible fibers that are currently used to produce composite materials. Agitation can lead to aerosolized CNTs and CNFs, and peak airborne particulate concentrations are associated with workplace activities such as weighing, transferring, mixing, blending, or sonication. Most airborne CNTs or CNFs found in workplaces are loose agglomerates of micrometer diameter. However, due to their low density, they linger in workplace air for a considerable time, and a large fraction of these structures are respirable. In rat and mouse models, pulmonary exposure to single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), or CNFs causes the following pulmonary reactions: acute pulmonary inflammation and injury, rapid and persistent formation of granulomatous lesions at deposition sites of large CNT agglomerates, and rapid and progressive alveolar interstitial fibrosis at deposition sites of more dispersed CNT or CNF structures. Pulmonary exposure to SWCNTs can induce oxidant stress in aortic tissue and increases plaque formation in an atherosclerotic mouse model. Pulmonary exposure to MWCNTs depresses the ability of coronary arterioles to respond to dilators. These cardiovascular effects may result from neurogenic signals from sensory irritant receptors in the lung. Pulmonary exposure to MWCNTs also upregulates mRNA for inflammatory mediators in selected brain regions, and pulmonary exposure to SWCNTs upregulates the baroreceptor reflex. In addition, pulmonary exposure to

  15. Excitation transfer and luminescence in porphyrin-carbon nanotube complexes

    OpenAIRE

    Magadur, Gurvan; Lauret, Jean-Sébastien; Alain-Rizzo, Valérie; C. Voisin; Roussignol, Ph.; Deleporte, Emmanuelle; Delaire, Jacques,

    2007-01-01

    Functionalization of carbon nanotubes with hydrosoluble porphyrins (TPPS) is achieved by "$\\pi$-stacking". The porphyrin/nanotube interaction is studied by means of optical absorption, photoluminescence and photoluminescence excitation spectroscopies. The main absorption line of the porphyrins adsorbed on nanotubes exhibits a 120 meV red shift, which we ascribe to a flattening of the molecule in order to optimize $\\pi-\\pi$ interactions. The porphyrin-nanotube complex shows a strong quenching ...

  16. Exciton decay dynamics in individual carbon nanotubes at room temperature

    OpenAIRE

    Gokus, Tobias; Hartschuh, Achim; Harutyunyan, Hayk; Allegrini, Maria; Hennrich, Frank; Kappes, Manfred; Green, Alexander A.; Hersam, Mark C.; Araujo, Paulo T.; Jorio, Ado

    2008-01-01

    We studied the exciton decay dynamics of individual semiconducting single-walled carbon nanotubes at room temperature using time-resolved photoluminescence spectroscopy. The photoluminescence decay from nanotubes of the same (n,m) type follows a single exponential decay function, however, with lifetimes varying between about 1 and 40 ps from nanotube to nanotube. A correlation between broad photoluminescence spectra and short lifetimes was found and explained by defects promoting both nonradi...

  17. Modelling the elastic behaviour of carbon nanotube-reinforced composites

    OpenAIRE

    Otero-Gruer, Fermín; Oller Martínez, Sergio Horacio; Martínez García, Javier; Salomón, Ramón Omar

    2011-01-01

    Carbon nanotubes (CNTs), since their discovery by Lij ima in 1991 [1], are considered a new generation of reinforcement [2]. Their "nano" size structure makes them potentially free of defects, which provides them with excellent physical properties [3,4]. There are two main nanotube types: single wall nanotubes (SWNT), which are made of a single wall tube; and multiwall nanotubes (MWNT), which consist in several concentric walls, one inside the other. In a composite, one the most importa...

  18. Numerical modelling of behaviour of carbon nanotube-reinforced composites

    OpenAIRE

    Otero-Gruer, Fermín; Oller Martínez, Sergio Horacio; Martínez García, Javier; Salomón, Ramón Omar

    2011-01-01

    Since their discovery by Lijima in 1991[1], carbon nanotubes (CNTs), are considered a new generation of reinforcement [2]. Their "nano" size structure makes them potentially free of defects, which provides them with excellent physical properties [3,4]. There are two main nanotube types: single wall nanotubes (SWNT) and multi wall nanotubes (MWNT). These last ones consist in several concentric walls, one inside the other. In a composite, one the most important factors that condition thei...

  19. Synthesis and characterization of carbon nanotube reinforced copper thin films

    OpenAIRE

    Otto, Cornelia

    2006-01-01

    Two model composites of copper and carbon nanotubes were fabricated by very different deposition methods. Copper electrodeposition in a plating bath containing nanotubes created a 3D matrix of randomly oriented CNTs within a thick, 20 micron Cu film. In contrast, sandwiching a layer of well-separated nanotubes between two sub-micron sputtered Cu layers produced a 2D-composite with nanotubes lying parallel to the substrate surface. These composites, which were mechanically tested using var...

  20. Carbon Nanotubes:from Nanoscale Building Blocks to Macrostructures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Carbon nanotubes (CNTs) have fascinating properties.In order to use these novel one-dimensional structures for applications such as in nano-electronic,nano-mechanical and electrochemical energy storage device and as structural elements in various composites,the structure of nanotubes needs to be tailored and various architectures and macroscale assembles have to be configured using nanotube building blocks.Nanotube macrostructures are macroscopically organized groups of CNTs,which are expecte...

  1. Electronic transport properties of metallic single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    曹觉先; 颜晓红; 肖杨; 丁建文

    2003-01-01

    We have calculated the differential conductance of metallic carbon nanotubes by the scatter matrix method. It is found that the differential conductance of metallic nanotube-based devices oscillates as a function of the bias voltage between the two leads and the gate voltage. Oscillation period T is directly proportional to the reciprocal of nanotube length. In addition, we found that electronic transport properties are sensitive to variation of the length of the nanotube.

  2. Inherent-opening-controlled pattern formation in carbon nanotube arrays

    OpenAIRE

    Huang, Xiao; Zhou, Jijie J.; Sansom, Elijah; Gharib, Morteza; Haur, Sow Chorng

    2007-01-01

    We have introduced inherent openings into densely packed carbon nanotube arrays to study self-organized pattern formation when the arrays undergo a wetting–dewetting treatment from nanotube tips. These inherent openings, made of circular or elongated hollows in nanotube mats, serve as dewetting centres, from where liquid recedes from. As the dewetting centres initiate dry zones and the dry zones expand, surrounding nanotubes are pulled away from the dewetting centres by liquid surface tension...

  3. In-situ observations of catalyst dynamics during surface-bound carbon nanotube nucleation

    DEFF Research Database (Denmark)

    Hofmann, S; Sharma, R; Du, G;

    2007-01-01

    We present atomic-scale, video-rate environmental transmission electron microscopy and in situ time-resolved X-ray photoelectron spectroscopy of surface-bound catalytic chemical vapor deposition of single-walled carbon nanotubes and nanofibers. We observe that transition metal catalyst...... nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself....... For a carbon nanofiber, the graphene layer stacking is determined by the successive elongation and contraction of the catalyst nanoparticle at its tip....

  4. Studies of DNA-carbon nanotube interactions

    Science.gov (United States)

    Hughes, Mary Elizabeth

    2008-10-01

    Recently a new biomaterial consisting of a DNA-wrapped single-walled carbon nanotube, and known as a DNA/SWNT, has been discovered. The possible applications of this hybrid are varied and range from genomic sequencing to nanoscale electronics to molecular delivery. The realization of these potential applications requires more knowledge about the microscopic properties of this material. In this thesis, I present studies of: the orientation of nucleobases on the nanotube sidewall; the sequence and length dependence of the DNA-nanotube interaction; and solution conditions to manipulate the DNA/SWNT hybrid. The measurement of the UV optical absorbance of DNA/SWNT and the nucleotide absorbance from DNA/SWNT provide the first experimental confirmation that DNA binds to nanotubes through pi-stacking. Because the hypochromic absorbance typical of pi-stacked structures are expected to occur primarily for DNA dipole transitions that lie along the axis of the optically anisotropic SWNTs, the absorbance changes following binding of DNA to the nanotubes reveals the preferred orientation assumed by each of the four bound nucleotides with respect to the nanotube's long axis. The first observations of pronounced sequence- and length-dependent variations in the binding between ssDNA and SWNTs in aqueous solution are presented. These observations rely on the discovery that there exists a range of DNA lengths able to hybridize with SWNTs that can nevertheless be dissociated at temperatures below the boiling point of water. Quantitative results comparing the isochronal dissociation temperatures and binding energies of DNA/SWNT composed of differing DNA sequences and lengths are given. These results indicate variability and complexity in the binding mechanism responsible for the stability of the hybrid system that transcends simple models based on the sum of independent base-nanotube interactions. Binding energies between a DNA base and nanotube (0.05 to 0.09 eV per base) are similar

  5. Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

    Science.gov (United States)

    Makarova, T. L.; Zakharchuk, I.; Geydt, P.; Lahderanta, E.; Komlev, A. A.; Zyrianova, A. A.; Kanygin, M. A.; Sedelnikova, O. V.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

    2016-10-01

    Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

  6. Terahertz response of carbon nanotubes and graphene

    International Nuclear Information System (INIS)

    The terahertz (THz) research field is expected to serve as a new platform for studying low-energy excitation in solids and higher-order structures in large molecules, and for realizing applications in medicine, agriculture, security, and high-capacity communications. The THz frequency region, however, is located between the electronic and photonic bands, hampering the development of basic components like detectors and sources. This article presents an overview of basic background information about THz waves and THz detector applications and describes the THz response of carbon-based low-dimensional systems, such as single carbon nanotubes (CNT), CNT-array films, and graphene. (author)

  7. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Jarillo-Herrero, P.D.

    2005-01-01

    Electronic transport through nanostructures can be very different from trans- port in macroscopic conductors, especially at low temperatures. Carbon na- notubes are tiny cylinders made of carbon atoms. Their remarkable electronic and mechanical properties, together with their small size (a few nm in

  8. Carbon nanotube materials for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, A.C.; Jones, K.M.; Heben, M.J. [National Renewable Energy Lab., Golden, CO (United States)

    1996-10-01

    Hydrogen burns pollution-free and may be produced from renewable energy resources. It is therefore an ideal candidate to replace fossil fuels as an energy carrier. However, the lack of a convenient and cost-effective hydrogen storage system greatly impedes the wide-scale use of hydrogen in both domestic and international markets. Although several hydrogen storage options exist, no approach satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. A material consisting exclusively of micropores with molecular dimensions could simultaneously meet all of the requirements for transportation use if the interaction energy for hydrogen was sufficiently strong to cause hydrogen adsorption at ambient temperatures. Small diameter ({approx}1 mm) carbon single-wall nanotubes (SWNTs) are elongated micropores of molecular dimensions, and materials composed predominantly of SWNTs may prove to be the ideal adsorbent for ambient temperature storage of hydrogen. Last year the authors reported that hydrogen could be adsorbed on arc-generated soots containing 12{Angstrom} diameter nanotubes at temperatures in excess of 285K. In this past year they have learned that such adsorption does not occur on activated carbon materials, and that the cobalt nanoparticles present in their arc-generated soots are not responsible for the hydrogen which is stable at 285 K. These results indicate that enhanced adsorption forces within the internal cavities of the SWNTs are active in stabilizing hydrogen at elevated temperatures. This enhanced stability could lead to effective hydrogen storage under ambient temperature conditions. In the past year the authors have also demonstrated that single-wall carbon nanotubes in arc-generated soots may be selectively opened by oxidation in H{sub 2}O resulting in improved hydrogen adsorption, and they have estimated experimentally that the amount of hydrogen stored is {approximately}10% of the nanotube weight.

  9. Carbon nanotube-based functional materials for optical limiting.

    Science.gov (United States)

    Chen, Yu; Lin, Ying; Liu, Ying; Doyle, James; He, Nan; Zhuang, Xiaodong; Bai, Jinrui; Blau, Werner J

    2007-01-01

    Optical limiting is an important application of nonlinear optics, useful for the protection of human eyes, optical elements, and optical sensors from intense laser pulses. An optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The optical limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent optical limiting responses. In the former case the optical limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real optical limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The optical limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the optical limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the optical limiting. Further improvements in the optical limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by

  10. Preparation of Isolated Single-walled Carbon Nanotubes with High Hydrogen Storage Capacity

    Institute of Scientific and Technical Information of China (English)

    张艾飞; 刘吉平; 吕广庶; 刘华

    2006-01-01

    Isolated single-walled carbon nanotubes with high proportion of opening tips were synthesized by using alcohol as carbon source. The mechanism of cutting action of oxygen was proposed to explain its growth. Compared with carbon nanotubes synthesized with benzene as carbon source, their specific surface area was heightened by approximately 2.2 times (from 200.5 to 648 m2/g) and the hydrogen storage capacity was increased by approximately 6.5 times (from 0.95 to 7.17%, ω)which had exceeded DOE energy standard of vehicular hydrogen storage.

  11. Controlled synthesis of high quality carbon nanotubes and their applications in transparent conductive films

    Science.gov (United States)

    Dervishi, Enkeleda

    Carbon nanotubes (CNTs) have exceptional electrical, mechanical and electronic properties which make them attractive for numerous applications. Catalytic chemical vapor deposition (cCVD) is one of the most promising methods for large-scale production of high-quality CNTs at a relatively low cost. Synthesis conditions such as catalyst composition, reaction temperature, hydrocarbon type and flow rate, have an enormous influence on the morphological properties of nanotubes. This research presents a thorough study of the parametric conditions affecting the growth properties of single-wall and multi-wall carbon nanotubes. High quality single-wall carbon nanotubes (SWCNTs) were synthesized on different catalytic systems, using the inductive radio frequency cCVD method. The catalyst compositions, as well as, the reaction temperatures were varied and methane or acetylene was separately utilized as the hydrocarbon source. Noticeable differences when it comes to the size controllability of the catalyst active nano-particles and the nanotube morphology were observed at these different reaction conditions. High efficiency multi-wall carbon nanotubes (MWCNTs) were synthesized from the pyrolytic decomposition of acetylene over Fe-Co/CaCO3. The catalyst stoichiometry was found to strongly influence the carbon deposition rate and the nanotube crystallinity characteristics. A comprehensive comparison was made between two different type of heating methods (resistive heating with external oven and inductive heating) with regards to gas utilization, the formation of amorphous carbon, nanotube morphology and growth efficiency. The structural and morphological properties of CNTs and of catalytic systems were analyzed by microscopy, X-ray diffraction, surface area analyzer, thermogravimetric analysis, Raman, and UV-Vis-NIR spectroscopy. MWCNTs synthesized by radio frequency cCVD have smaller outside diameters, larger inner diameters, fewer numbers of graphitic walls, less amorphous

  12. Black silicon maskless templates for carbon nanotube forests

    DEFF Research Database (Denmark)

    Wierzbicki, Rafal; Schmidt, Michael Stenbæk; Boisen, Anja;

    2013-01-01

    We present here a proof of concept for a novel fabrication method of vertically aligned carbon nanotube forests, utilizing black silicon nanograss (a forest of silicon nanometer-sized spikes created with reactive ion etching) coated with titanium tungsten diffusion barrier as a template. The method...... allows maskless definition of carbon nanotube forests with control of their density, nanotube diameter and height. Four nanograss reactive ion etching recipes are investigated and their wafer-to-wafer repeatability, wafer uniformity, and density control is discussed. Evaluation of carbon nanotube forests...

  13. Preparation of array of long carbon nanotubes and fibers therefrom

    Science.gov (United States)

    Arendt, Paul N.; DePaula, Ramond F.; Zhu, Yuntian T.; Usov, Igor O.

    2015-11-19

    An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

  14. Fabrication, structure, and electron emission of single carbon nanotubes

    Science.gov (United States)

    Zhao, Gongpu

    Carbon nanotubes possess many excellent field emission properties. An obstacle to these applications is that there is no simple and reproducible method to prepare a single carbon nanotube field emitter. In this dissertation, individual carbon nanotube field emitters have been fabricated in a two-step process involving (a) producing micron-size carbon fibers which contain single carbon nanotubes at their cores and (b) exposing the nanotubes by fracturing the fiber with mechanical forces and mounting the fiber to a copper ribbon with a groove. This fabrication method has the potential to be the production method for single carbon nanotube field emission point electron sources. The cold field emission properties of single carbon nanotubes have been studied. These carbon nanotubes exhibit large field enhancement factors of 1.1x107 m-1 and low turn-on fields of 1.1 V/mum. An empirical model has been developed to calculate the field enhancement factor of an open end nanotube attached on a carbon fiber. The lifetime measurements show that a single carbon nanotube can continuously emit electrons over 100 hours without significant current drops. The emission stability measurements show that the maximum current drift is 3.6%. It is also shown experimentally that a carbon nanotube has a high reduced brightness 2.9x 108 ASr-1m-2 V-1, which is two orders of magnitude higher than those of the thermionic electron sources. The thermal field emission properties of a single carbon nanotube have been systemically studied. It is found that there is a gap between the intermediate region and the field emission region which is not covered by either the Fowler-Nordheim theory or the Murphy-Good theory. We have developed an analytical equation that describes the thermal field emission behavior of a single carbon nanotube within the gap. The experimental results agree well with the theoretical predictions. We also studied the effect of Cs doping on the field emission properties and

  15. Fullerene and nanotube growth: new insights using first principles and molecular dynamics.

    Science.gov (United States)

    Cruz-Silva, Rodolfo; Araki, Takumi; Hayashi, Takuya; Terrones, Humberto; Terrones, Mauricio; Endo, Morinobu

    2016-09-13

    Shortly after the discovery of fullerenes, many researchers pointed out that carbon nanotubes could be considered as elongated fullerenes. However, the detailed formation mechanism for both structures has been a topic of debate for several years, and consequently it has been difficult to draw a clear connection between the two systems. While the synthesis conditions appear to be different for both fullerenes and nanotubes, here, we demonstrate that it is highly likely that, at an initial growth stage, single-walled carbon nanotubes begin to grow from a hemisphere-like fullerene cap. More importantly, by analysing the minimum-energy path, it is shown that the insertion of C2 fragments drives the transformation of this fullerene cap into an elongated structure that leads to the formation of very short carbon nanotubes.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'. PMID:27501974

  16. A carbon nanotube immunosensor for Salmonella

    Directory of Open Access Journals (Sweden)

    Mitchell B. Lerner

    2011-12-01

    Full Text Available Antibody-functionalized carbon nanotube devices have been suggested for use as bacterial detectors for monitoring of food purity in transit from the farm to the kitchen. Here we report progress towards that goal by demonstrating specific detection of Salmonella in complex nutrient broth solutions using nanotube transistors functionalized with covalently-bound anti-Salmonella antibodies. The small size of the active device region makes them compatible with integration in large-scale arrays. We find that the on-state current of the transistor is sensitive specifically to the Salmonella concentration and saturates at low concentration (<1000 cfu/ml. In contrast, the carrier mobility is affected comparably by Salmonella and other bacteria types, with no sign of saturation even at much larger concentrations (108 cfu/ml.

  17. Batch fabrication of carbon nanotube bearings

    International Nuclear Information System (INIS)

    Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes (MWNTs) can be used as a robust nanoscale motion enabling mechanism. Here, we report on a novel method suited for structuring large arrays of MWNTs into such nanobearings in a parallel fashion. By creating MWNT nanostructures with nearly identical electrical circuit resistance and heat transport conditions, uniform Joule heating across the array is used to simultaneously engineer the shell geometry via electric breakdown. The biasing approach used optimizes process metrics such as yield and cycle-time. We also present the parallel and piecewise shell engineering at different segments of a single nanotube to construct multiple, but independent, high density bearings. We anticipate this method for constructing electromechanical building blocks to be a fundamental unit process for manufacturing future nanoelectromechanical systems (NEMS) with sophisticated architectures and to drive several nanoscale transduction applications such as GHz-oscillators, shuttles, memories, syringes and actuators

  18. Carbon nanotube as a gramicidin analogue

    Science.gov (United States)

    Hilder, Tamsyn A.; Chung, Shin-Ho

    2011-01-01

    We have designed a carbon nanotube that is selectively permeable to monovalent cations, binds divalent cations and rejects anions. The nanotubes, with an effective radius of 4.53 Å and length of 36 Å, are terminated with hydrogen atoms and are exohydrogenated in two regions near the entrance and exit. Using molecular and stochastic dynamics simulations we examine the free energy, current-voltage-concentration profiles and ion binding sites. The characteristics of this channel are comparable to the antibiotic gramicidin-A, but the potassium current is six times larger. At 40 mM calcium concentration the current is reduced from 26 pA to 4 pA due to a calcium ion binding at the channel entrance.

  19. Raman Spectroscopic Studies of Carbon Nanotube Composite Fibres

    OpenAIRE

    Deng, Libo

    2011-01-01

    The project has been concerned with structure/property relationships in a series of different carbon nanotube (CNT) composite fibres. Raman spectroscopy has been proved to be a powerful technique to characterise the CNT-containing fibres. Electrospinning has been used to prepare poly(vinyl alcohol) (PVA) nanofibres containing single-wall carbon nanotubes (SWNTs). The effect of the processing conditions including the polymer concentration, electric voltage, tip-to-collector distance, nanotube ...

  20. Carbon Nanotubes Synthesis via Arc Discharge with a Yttria Catalyst

    OpenAIRE

    M. I. Mohammad; Ahmed A. Moosa; J.H. Potgieter; Mustafa K. Ismael

    2013-01-01

    A facile method is proposed to use a computer controlled Arc discharge gap between graphite electrodes together with an yttria-nickel catalyst to synthesize carbon nanotubes under an Ar-H2 gases mixture atmosphere by applying different DC currents and pressure. This produces carbon nanotubes with decreased diameters and increased length. XRD evidence indicated a shift toward higher crystallinity nanotubes. Yields of the CNTs after purification were also enhanced.