Aligned carbon nanotube films for cold cathode applications

Obraztsov, A. N.; Pavlovsky, Igor; Волков, А. П.; Obraztsova, E. D.; Chuvilin, Andrey; Кузнецов, В. Л.

doi:10.1116/1.591328

Cited by 58 publications

(28 citation statements)

References 17 publications

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“…For example, surfactants have been used to template the synthesis of MCM-41, [5] or other porous silicates [6,7] and oxides. [8] The use of microporous zeolites such as Y, ZSM-5, mordenite, L and more recently beta (BEA) as templates, [9,10] has been investigated to produce carbon materials with a controlled microporosity. Moreover, zeolites, such as Y, ZSM-5, BEA, used as supports of transition metal catalyst, [11±14] permit to produce carbon nanotubes by catalytic decomposition of different hydrocarbons.…”

Section: Characterization Of Nanocarbons Produced By Cvd Of Ethylene mentioning

confidence: 99%

“…[3] Nanomanipulation techniques have been used for fabricating single-nanotube devices, such as sensors and field effect transistors, [4±6] but the probability of selecting the proper nanotubes needed for device function is low and these techniques are generally much too inefficient and unreliable to be used for making commercial practice. Nevertheless, strategies have been developed and practiced in the laboratory for fabricating carbon nanotube forests and other oriented nanotube assemblies (which can be used for field emitting devices), [7,8] self-standing carbon nanotube films (the so-called ªbucky-papersº), [9,10] and polymer and ceramic composites. [2,11±15] The addition of carbon nanotubes to polymeric or epoxy matrices results in composites with enhanced mechanical properties and electronic transport.…”

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confidence: 99%

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Multifunctional Carbon Nanotube Composite Fibers

Muñoz¹,

Dalton

Collins

et al. 2004

Adv Eng Mater

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Carbon nanotubes have been the focus of considerable research over the last decade. Because of their remarkable structural, mechanical, electrical, and thermal properties, [1] diverse applications have been envisioned. [2] Realization of these property advantages has been frustrated by material heterogeneity and impurities: catalyst and/or impurity carbons are present and as-produced nanotubes are mixtures of moderate bandgap semiconductors, very small bandgap semiconductors, and metallic conductors. Also, single-wall nanotubes (SWNTs) aggregate into bundles and larger, morerandom assemblies, and are difficult to uniformly disperse in melt or solution as either bundles or individual nanotubes. [3] Nanomanipulation techniques have been used for fabricating single-nanotube devices, such as sensors and field effect transistors, [4±6] but the probability of selecting the proper nanotubes needed for device function is low and these techniques are generally much too inefficient and unreliable to be used for making commercial practice. Nevertheless, strategies have been developed and practiced in the laboratory for fabricating carbon nanotube forests and other oriented nanotube assemblies (which can be used for field emitting devices), [7,8] self-standing carbon nanotube films (the so-called ªbucky-papersº), [9,10] and polymer and ceramic composites. [2,11±15] The addition of carbon nanotubes to polymeric or epoxy matrices results in composites with enhanced mechanical properties and electronic transport. [2,11,13] Composites of multiwall nanotubes (MWNTs) have been employed for initial practical applications, such as enabling electrostatic painting of automotive parts, and are of great interest for radio-frequency and electromagnetic shielding. [2,16] We have recently shown that intercalation of polymers in the porous structure of nanotube sheets increases Young's modulus, strength and toughness by factors of up to 3, 9, and 28, respectively. [17] The fabrication of carbon nanotube containing fibers is of special interest for mechanical and electronic textile applications. [18,19] Vigolo et al. developed an innovative coagulationbased fiber spinning technique: first, an aqueous dispersion of arc-discharge-produced single-wall carbon nanotubes (SWNTs) and surfactant (sodium dodecyl sulfate) is injected into a rotating bath of aqueous polyvinyl alcohol (PVA) solution, which serves as coagulant. [20±22] The nanotubes collapse during coagulation to form ribbon-like elastomeric gel-fibers. [23] Such gel-fibers are washed by immersion in successive water containers to remove excess PVA, and then dried by pulling from the water bath. The gel-fibers spun by this technique are difficult to disentangle and too weak to be easily handled. As a result, the produced dried fibers were typically short (some tens of centimeters long). Tensile strength and Young's modulus values of up to 230 MPa and 40 GPa, respectively, were reported for those dried SWNT/ PVA composite fibers. [20±22] This coagulation-based fiber spinning techniq...

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Section: Characterization Of Nanocarbons Produced By Cvd Of Ethylene mentioning

confidence: 99%

mentioning

confidence: 99%

Multifunctional Carbon Nanotube Composite Fibers

Muñoz¹,

Dalton

Collins

et al. 2004

Adv Eng Mater

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“…Wherever the catalyst nanoparticles are found in growth experiments, i.e., on the NT tips or on the substrate, the majority of experimental reports refer to a model of carbon filament growth by continuous C diffusion or extrusion through the metal nanoparticle 29-31 ͑''tip'' or ''base'' growth model͒. However, NT forests have also successfully been grown by plasma enhanced CVD even without a catalyst, 28 suggesting that another kinetical mechanism may be involved in this process. Additionally, in our recent communication 32 we have provided an order to magnitude analysis of CVD process of carbon NT forest growth outlining several contradictions which arise in the application of the model [29][30][31] for a particular experimental study where the Fe catalyst remained at the bottom.…”

Section: Introductionmentioning

confidence: 98%

Diffusion-controlled kinetics of carbon nanotube forest growth by chemical vapor deposition

Louchev

Laude

Sato

et al. 2003

The Journal of Chemical Physics

116

102

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A detailed theoretical study of carbon nanotube (NT) forest growth by chemical vapor deposition is given, including (i) ballistic mode of carbon species impingement into the NT surface, (ii) the carbon diffusion over NT surface and through the metal nanoparticle, and (iii) the temperature drop at the NT tip occurring with increase in NT length. For typical NT forest growth parameters the ballistic flux of carbon species impinging into the NT surface decays quasiexponentially within several microns from the top. A variety of feasible growth modes, ranging from linear to exponential versus time, is predicted agreeing well with reported experiments. The presence of a metal nanoparticle is shown to shift NT growth from being surface diffusion controlled to being controlled by bulk diffusion through the nanoparticle. For typical growth conditions the growth rate is shown to be controlled simultaneously by surface diffusion over NT surface and bulk diffusion of carbon through metal nanoparticle. However, even in specific cases where NT growth rate is controlled by bulk diffusion through the nanoparticle the initial stage may be controlled by surface diffusion, as revealed by the exponential change in NT length with time. A parametric study of the growth rate of NT forest with metal nanoparticles held at the NT tips as a function of temperature reveals the existence of a maximum near 1050–1100 K, agreeing with reported experimental data. A thermal analysis based upon the heat conductance equation shows that with NT forest growth the temperature of the NT tips decreases, leading to growth deceleration and termination. Our study shows that the larger the pressure the smaller the NT forest height that may be grown. In particular, for pressures ≈105 Pa the NT tips should be “frozen” even at a length of a few microns, disabling further NT growth. In contrast, under low pressures of ≈103 Pa NT forest of several dozens of microns may be successfully grown without significant growth deceleration.

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“…The high-resolution transmission electron microscopy micrograph of NCNTs showed that nanonodes usually have high curvature surfaces. Obraztsov et al 7,8 have proposed a CNT field emission model in which carbon atoms tend to have bonds similar to sp 3 other than the normal sp 2 of graphite. In the graphite lattice, carbon atoms are bonded in planar layers with sp 2 bonds.…”

Section: Field Emission Of Nodular Carbon Nanotubesmentioning

confidence: 99%

Field emission characteristics of nodular carbon nanotubes

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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A configuration of carbon nanotubes (CNTs) whose surfaces were fully covered with nanoscale nodes was developed in our laboratory. We named this material nodular CNTs or NCNTs. A hydrogen plasma process was used to turn common CNTs into NCNTs. Combined with this process, a technique has been developed to make planar NCNTs field emitters. Field emission experiments showed that planar NCNTs emitters had superior field emission characteristics. Specifically, the emission site density was increased by the order of 106/cm2. A suggestion was given to interpret the formation of NCNTs and a simple model was also proposed to explain the improvement of field emission properties. This technique was found to be an easy way to change the geometric character of CNTs in large quantities and will be useful for creating planar field emitters used in field emitter light sources or display devices.

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Aligned carbon nanotube films for cold cathode applications

Cited by 58 publications

References 17 publications

Multifunctional Carbon Nanotube Composite Fibers

Multifunctional Carbon Nanotube Composite Fibers

Diffusion-controlled kinetics of carbon nanotube forest growth by chemical vapor deposition

Field emission characteristics of nodular carbon nanotubes

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