Electric arc-discharge

The laser-ablation method can produce SWCNT under co-evaporation of metals like in the electric arc-discharge method. As metallic catalyst Fe, Co or Ni plays the important role and their combination or addition of the third element such as Y produces SWCNT in an efficient manner. But it is still difficult in the laser-ablation method to produce gram quantity of SWCNT. Nonetheless, remarkable progress in the research of physical properties has been achieved in thus synthesized SWCNT. 

Until recently, synthesis of nanostructured carbon materials was usually based on very harsh conditions such as electric arc discharge techniques [1], chemical vapor deposition [2], or catalytic pyrolysis of organic compounds [3]. In addition (excluding activated carbons), only little research has been done to synthesize and recognize the structure of carbon materials based on natural resources. This is somewhat hard to understand, as carbon structure synthesis has been practiced from the beginning of civilization on the base of biomass, with the petrochemical age only being a late deviation. A refined approach towards advanced carbon synthesis based on renewable resources would be significant, as the final products provide an important perspective for modern material systems and devices. 

SWCNTs exhibit unique physical and chemical properties that make them very attractive candidates for the production of new materials. Carbon nanotubes are made by wrapping up single sheets of graphite, known as graphene, upon themselves to form hollow, straw-like structures. Traditionally, SWCNTs have been prepared by electric arc-discharge, laser ablation and chemical vapor deposition (CVD) methods these techniques produce significant quantities of impurities, such as amorphous and graphitic forms of carbon and encapsulated catalytic metal nanoparticles. 

In 1997 Journet et al. (23) described a method to obtain high yields of SWCNTs by means of electric arc-discharge, using a transition metal mixture (Nickel and Yttrium) as catalyst. In a typical arc reactor,... 

Nanostracturing processes for carbon Electric arc discharge [142,143] Laser ablation [144,145] Chemical vapor deposition [146] Combustion [147]... 

Figure 22 Typical size distribution of carbon MWNT synthesized using the electric arc discharge method (a) external diameter (b) inner diameter.

By condensation of carbon vapor obtained by electrical arc discharge Tanuma [15] obtained a quasi one-dimensional carbon crystal, but the carbon chain only consisting of four atoms. The specific weight was 1.46g/cm. This value is smaller than the values of 2.68 g/cm of a-carbyne and 3.13 g/cm of p-carbyne. The crystals were metastable at temperature above 350 K. Tsuji et al. [16,17] have shown that polyynes in solution can be generated by laser... 

Tanuma, S. Condensation of carbon vapor obtained by electrical arc discharge. In Carbyne and Carbynoid Structures. Kluwer Academic Publishers Dordrecht/Boston/London, 1999 149-158. 

We have recently studied laser ablation of graphite and Ceo particles suspended in solutions [6,7]. It was found that hydrogen-capped polyynes (C2 H2 = 4-8) were produced from graphite particles suspended in benzene, toluene, or hexane solution [6], while C2 H2 (n = 4-6) polyynes were formed from Cgo in hexane or methanol solution [7]. Cataldo [8,9] has recently synthesized C2 H2 (n = 2-9) polyynes by a submerged electric arc discharge in organic solvents. 

Frolova, I.B., Minkin, VM., Frolov, VA. (1976), Treatment of Dispersed Oxides of Iron, Chromium and Nickel by Reducing Gases Heated Up in Electric Arc Discharge, in Plasma Processes in Metallurgy and Technology of Inorganic Materials, A. A. Baikov Institute of Metallurgy of USSR Academy of Sciences, Nauka (Science), Moscow. 

Nanoparticles can be produced by several methods including mechanical, electric arc discharge, laser ablation, chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD) and wet chemical reactions. 

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