Some properties of solid fractal structures in carbon nanofibers

Золотухин, И. В.; Golev, I. M.; Marková, Aneta; Panin, Yu. V.; Sokolov, Yu. V.; Ткачев, А. Г.; Negrov, Vladimir L.

doi:10.1134/s1063785006030060

Cited by 7 publications

(7 citation statements)

References 2 publications

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“…Despite the huge interest in polymer/CNT composites as novel TE materials above commented, very limited research has been focused on studying the TE properties of a different type of carbon nanostructure known as carbon nanofibers (CNF), which are similar to carbon nanotubes but show different physical and chemical properties because of their larger diameters and less perfect outer layers with a range of angles related to their graphitic tubular core [13]. Among the very few works focused on the analysis of TE properties of CNF, the authors have found a single study where self-organized macroscopic solid structures consisting of CNF grown by means of methane pyrolysis in the presence of NiO as a catalyst, showed a negative Seebeck coefficient of -11 μVK −1 [14]. More recently, solution mixed polymer composites of ethylene-octene copolymer (ECO) and CNF were reported with positives TEP of 14 μVK −1 [15].…”

Section: Introductionmentioning

confidence: 99%

Negative thermoelectric power of melt mixed vapor grown carbon nanofiber polypropylene composites

Paleo¹,

Vieira²,

Wan³

et al. 2019

Carbon

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In this work, commercial vapor grown carbon nanofibers (CNF), produced by chemical vapor deposition (CVD), were melt extruded with polypropylene (PP) with the aim of analyzing their thermoelectric properties (i.e., electrical conductivity, thermoelectric power, power factor and figure of merit). Unexpectedly, all PP/CNF composites, instead of showing the typical positive thermoelectric powers (TEP) observed for this type of carbon-based polymer composites, they showed negative TEP values.These results can be attributed to the double layer structure surrounding the tubular core of the carbon nanofiber grown by the CVD method at 1100 ºC, which may lead to that the intrinsically negative TEP from the inner shells counteract the positive TEP contribution from the outer surface shells of CNF due to oxygen doping. Overall, all composites showed negative TEP values around -8.5 μVK−1, and a maximum power factor of 1.75 × 10-3 μW m-1 K-2, corresponding to a figure of merit of 4 × 10-9. This study demonstrates that melt mixed polymer composites with largediameter tubular carbon nanostructures and negative Seebeck coefficients can be directly produced with large-scale processing methods without requiring specific additives and/or deoxygenation treatments.

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Section: Introductionmentioning

confidence: 99%

Negative thermoelectric power of melt mixed vapor grown carbon nanofiber polypropylene composites

Paleo¹,

Vieira²,

Wan³

et al. 2019

Carbon

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“…It can be seen in Fig. 2 that, as this temperature increases, there occurs a gradual transition from the strong semiconductor temperature dependence to a weak quasi metallic temperature dependence and the resistivity of the carbon nanow ires decreases down to 0.03 Ω cm (which approxi mately corresponds to the resistivity of high quality carbon threads [14]). On the whole, the results of transport measurements are in good agreement with the assumption that the ordering of carbon atoms in the nanowires becomes better at a higher thermal treatment temperature.…”

Section: Fabrication Of Carbon Nanowires By Pyrolysis Of Aqueous Solumentioning

confidence: 97%

Fabrication of carbon nanowires by pyrolysis of aqueous solution of sugar within asbestos nanofibers

et al. 2015

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Carbon nanowires have been fabricated by pyrolysis of an aqueous solution of sugar in nanochan nels of asbestos fibers. Electron microscopy demonstrates that the diameter of these nanochannels corre sponds to the diameter of the thinnest of the carbon nanowires obtained. Some of these nanowires have a graphite crystal lattice and internal pores. After asbestos is etched out, the carbon nanowires can retain the original shape of the asbestos fibers. Heating in an inert atmosphere reduces the electrical resistivity of the carbon nanowires to ~0.035 Ω cm.

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“…However, the electrical properties of CHNF mats without polymer resin are not well established, so the feasibility of this material is difficult to estimate. A similar nanofiber, a NiO grown fractal nanofiber, was observed to have a resistivity ρ = 250 µΩ m and Seebeck coefficient S = 24 µV/K [12]. The electrical properties of CHNF are not yet well established, so this makes for a lower limit because of the high degree of .…”

Section: Thermal Transport Simulationmentioning

confidence: 99%

“…Because of the complex diversity of carbon nanofibers [4][5][6][7][8][9][10][11][12], we limit our study to those of conical internal geometry. The geometry of an annular cone formed from a graphene disc with bond-length b can be described by three independent parameters (n, m, k).…”

Section: Conical Nanofiber Geometrymentioning

confidence: 99%

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Non-equilibrium thermal transport simulation of conical carbon nanofibers

Thomas

Yamamoto

Tada

et al. 2013

Trans. Mat. Res. Soc. Japan

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Using non-equilibrium molecular dynamics, we study the thermal transport properties of conical carbon nanofibers, comparing with single-walled carbon nanotubes and graphene nanoribbons. Our results predict that the conical nanofibers have at least a two-order of magnitude smaller thermal conductivity. We then predict the potential applicability of conical-helix carbon nanofibers to nanoscale thermoelectric devices.

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Some properties of solid fractal structures in carbon nanofibers

Cited by 7 publications

References 2 publications

Negative thermoelectric power of melt mixed vapor grown carbon nanofiber polypropylene composites

Negative thermoelectric power of melt mixed vapor grown carbon nanofiber polypropylene composites

Fabrication of carbon nanowires by pyrolysis of aqueous solution of sugar within asbestos nanofibers

Non-equilibrium thermal transport simulation of conical carbon nanofibers

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