Preparation of single-walled nanotubes with the help of a Ni/Cr-based catalyst

Bezmelnitsyn, V.N.; Domantovskii, A. G.; Елецкий, А. В.; Obraztsova, E. D.; Pernbaum, A. G.; Prikhod’ko, K. E.; Терехов, С. В.

doi:10.1134/1.1470551

Cited by 8 publications

(6 citation statements)

References 11 publications

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“…Thus, the use of nichrome as a catalyst results in its embedding into carbon nanotissue. The result obtained is consistent with the data reported in [4][5][6][7].…”

Section: Nicr-pt 10supporting

confidence: 96%

“…Similar results were also obtained for Specimen 3, but the scattering intensities are by an order of magnitude lower. The carbon blacks manufactured using nichrome as a catalyst were investigated in [7] by the methods of scanning electron microscopy (SEM), Raman scattering (RS), and thermogravimetry. The data obtained by SEM revealed the presence of single-layer nanotubes combined into bundles a few microns long and nearly 100 Å wide, consisting of a few scores of nanotubes.…”

Section: Nicr-pt 10mentioning

confidence: 99%

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Radiographic examination of carbon nanotissues manufactured over different catalysts

et al. 2011

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UDC 539.26 Using the method of full-profile analysis of X-ray patterns obtained from polycrystals, the structure of carbon nanomaterials manufactured in the presence of a variety of catalysts is investigated. The unit cell period and phase concentration are specified. The formation of nanotubes with an interlayer spacing of 3.44 Å is established in the specimens under study.Keywords: carbon, nanomaterials, X-ray structure analysis.The purpose of this work is to investigate the structural features of carbon nanowebs based on the analysis of the distribution curves of X-ray scattering intensity.The X-ray radiographic investigations were performed with computer-aided DRON-3M and DRON-6 diffractometers using Fe-and CuK α -radiation. The X-ray patterns obtained were analyzed using a PdWin software package [1] and a PDR code for full-profile analysis of X-ray patterns from the crystals [2].The specimens were prepared by the electrospark-ignited combustion of a graphite electrode in the presence of a number of catalysts.During preparation of all specimens except for the first one, the anode consisted of four approximately identical graphite rods 8-9 cm in height. Their cross-section was square, with the side being 2.5 mm. The rods were assembled crosswise into a quadruple electrode that served as a master cathode. Before assembly into the master electrode, the carbon rods were processed in a water solution of iodine. The rods were separated by four thin plates of a respective catalyst placed in between the rods. The system geometry was selected in a way to use four different metals as catalysts. When preparing Specimen 1, the electrode had a sandwich structure, and no processing of the rods with iodine was performed. The helium pressure in the chamber for all of the tests was 600 Torr. Table 1 presented below lists the specimen number, the catalyst type, and special conditions of the specimen preparation.The X-ray patterns from Specimens 1-3 ( Fig. 1) contain five Bragg reflections in the vicinity of the scattering angles 2θ Cu > 40°. For the values 2θ Cu < 30°, there is a diffusion background, whose angular dependences are different. The most intensive low-angle scattering (2θ Cu = 2 to10°) is found in the X-ray pattern from Specimen 2, and the most pronounced diffusion peak (2θ Cu ∼ 17°) -in the X-ray pattern from Specimen 3. Against the background of this diffusion peak there is a narrow asymmetric peak towards the values of 2θ Cu ∼ 26.5°. The position of this peak is somewhat displaced from that corresponding to (002) graphite reflection (2θ Cu = 26.63°).The Bragg reflections observed in the X-ray patterns of all the three specimens ( Fig. 1) for the values of 2θ Cu > 40° correspond, both in their position and intensity, to the X-ray pattern from the material with an fcc-lattice. It is well known that solid solutions of chromium in nickel (nichrome) maintain their fcc-lattice till a chromium concentration of 15-20 wt.% [3]. According to the JCPDS data files, the lattice period of Ni is equal to a Ni = 3.5238 Å,

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“…Thus, the use of nichrome as a catalyst results in its embedding into carbon nanotissue. The result obtained is consistent with the data reported in [4][5][6][7].…”

Section: Nicr-pt 10supporting

confidence: 96%

Section: Nicr-pt 10mentioning

confidence: 99%

Radiographic examination of carbon nanotissues manufactured over different catalysts

et al. 2011

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“…At very high fields practically all the nanotubes are involved into the emission. These considerations have been confirmed directly in the experiment [ 86 ] where single walled nanotubes synthesized in an electrical arc discharge using Ni/Cr catalyst [ 87 ] were used as a source of the emission.…”

Section: Emission Properties Of a Cnt Arraymentioning

confidence: 78%

Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

Бочаров

Елецкий

2013

Nanomaterials

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Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.

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“…Indeed an experiment shows that Ni+Cr is more efficient than Ni alone for arc discharge growth of carbon nanotubes. 18 No experiments have been reported for the combinations Ni+Mo, Fe+Mo, and Co+Mo, which we expect to be the best catalysts. Some CVD experiments did find that Mo impurities enhance the yield of nanotubes combined with Fe or Co. 19,20 But this may not be relevant since the mechanism for CVD production of SWCN (likely involving nucleation and growth on the solid surface) is quite different than the gas phase growth for laser vaporization we are considering.…”

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confidence: 91%

A Two-Stage Mechanism of Bimetallic Catalyzed Growth of Single-Walled Carbon Nanotubes

2004

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Using quantum mechanics we examined critical steps in the growth of single-walled carbon nanotubes (SWCN) for Ni, Co, Pt, Cu, Cr, Fe, Mo, Rh, Pd, and their combinations. This suggests a two-stage mechanism consisting of nucleation of nanotube growth (determining the number of SWCN) and growth with defect repair (determining the length of SWCN) and suggests simple computational tests for efficacy. This leads to efficacies in the order Ni+Co > Ni+Pt > Ni > Ni+Cu, consistent with experiment. These results suggest that Mo+Ni would be a better bimetallic catalyst than the best current catalyst, Ni+Co.

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Preparation of single-walled nanotubes with the help of a Ni/Cr-based catalyst

Cited by 8 publications

References 11 publications

Radiographic examination of carbon nanotissues manufactured over different catalysts

Radiographic examination of carbon nanotissues manufactured over different catalysts

Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

A Two-Stage Mechanism of Bimetallic Catalyzed Growth of Single-Walled Carbon Nanotubes

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