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Various forms of nanotubes were produced by the AC arc discharge method at low He pressure. Some forms of nanotubes different from those which had been reported previously were found in the soot (but not the cathode deposit). These were the carbon nanocapsule, carbon cone-shaped nanotube and the carbon toroidal nanotube, respectively. The difference between the formation mechanisms by AC arc discharge...
In the present investigation, we have investigated the effect of external voltage (field) on the alignment of graphitic nanotubes as a result of applied electric field. The details of alignment effect embodying variation of applied electric field corresponding to applied voltage between 2 to 10 volts, the variation of length and diameter of the tubes have been studied. It has been found that both...
High quality multiwalled carbon nanotubes (MWNTs) prepared by hydrogen DC arc discharge were purified by infrared irradiation in air at about 500 o C. The morphology and nanostructure of the purified MWNTs were investigated by using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy. Each MWNT was highly graphitized and...
A conception about the mechanism of fullerene formation in carbon plasma is developed based on the influence of electron concentration on the stability of carbon clusters. Thermodynamic estimates for the efficiency of formation of spheroidal, flat clusters and linear carbon chains depending on the charge of the reacting particles are described. Strong influence of cluster charge upon the geometry...
The effect of varying current density and pressure during arc generation on the yield and purity of multi-walled nanotube-containing carbon soot has been studied in this work. Various soots were produced and characterised qualitatively using transmission electron microscopy and quantitatively using electron paramagnetic resonance and thermogravimetric analysis. It was found that both yield and purity...
Whatever the synthesis technique used, the growth of ropes of single-wall carbon nanotubes requires the assistance of a metallic catalyst. In this paper, the role played by the catalyst is studied both experimentally and theoretically. Experimentally, the similarities between the samples synthesized from different techniques suggest a common growth mechanism proceeding via the precipitation of excess...
A brittle porous deposit consisting of high-purity fibrous carbon products with a diameter of 25-100 nm was obtained on a heated anode surface in hydrogen DC arc-discharge. Hydrogen arc plasma was generated between a graphite cathode and a carbon/metal composite anode consisting of 1.0 at.% Fe, 0.6 at.% Co, 2.4 at.% Ni, and 0.4 at.% FeS. X-ray diffraction analysis revealed that the fibrous products...
We investigated plasma rotating electrode process (PREP) as a method for diameter control of single-walled carbon nanotubes (SWNTs) with a Ni-Y catalyst in He ambient. Compared with the diameters of SWNTs produced by the conventional arc discharge (0 rpm), those of SWNTs, which were synthesized by PREP (5000 and 10 000 rpm), were decreased. This result indicated that the centrifugal force by the...
The influence of electron concentration in ionized carbon vapor on C 60 fullerene formation was theoretically investigated. By considering C 60 molecule assembly at one or two intermediate stages of cluster collision we determined the plasma parameters (temperature and electron concentration) optimal for the fullerene synthesis. The estimations made showed that waves of electron...
Fe(C) and Ni(C) nanocapsules with low carbon content have been produced via an arc discharge process in ethanol vapor. It is clarified by X-ray diffraction that the core of the Fe(C) nanocapsules consists of γ-Fe, α-Fe and Fe 3 C phase, while that of the Ni(C) nanocapsules contains only nickel. High-resolution transmission electron microscopy imaging confirms that these particles have a broad...
A novel form of ball-like carbon material with its size in micrometer range was prepared from coal with nickel as catalyst by arc plasma method. The carbon material has been systematically studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and ultraviolet laser Raman spectroscopy. The SEM observation shows that the novel carbon material exists...
The unique properties of fullerenes have stimulated intensive research on fullerene-based materials for a wide range of applications, the hydrogen power industry being among them. However the high cost of fullerenes prevents their use for hydrogen storage. The only industrial method of fullerene production is arc discharge with graphite electrodes, but its optimum efficiency is far too low. Transformation...
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