CNTs laser ablation

Laser-ablation method shown in Fig. 3 was used when Cgo was first discovered in 1985 [15]. This method has also been applied for the synthesis of CNT, but length of MWCNT is much shorter than that by arc-discharge method [17]. Therefore, this method does not seem adequate to the synthesis of MWCNT. However, in the synthesis of SWCNT described later (Sec. 3.1.2), marvelously high yield has been obtained by this method. Hence, laser-ablation method has become another important technology in this respect. 

Despite the frequent use of arc-discharge and laser ablation techniques, both of these two methods suffer from some drawbacks. The first is that both methods involve evaporating the carbon source, which makes it difficult to scale up production to the industrial level using these approaches. Second, vaporization methods grow CNTs in highly tangled forms, mixed with unwanted forms of carbon and/or metal species. The CNTs thus produced are difficult to purify, manipulate, and assemble for building nanotube-device architectures in practical applications. 

CNTs are prepared by either laser ablation from graphite target, arc discharge, or chemical vapor deposition. In either case, to grow they need the presence of Co or Ni catalyst. Typically, outer diameter of CNTs prepared by a carbon arc process ranges between 20 and 200 A, and inner diameter ranges between 10 and 30 A. An aspect ratio (length-to-diameter ratio) is typically of 10 -10. ... 

In the case of carbon nanotubes (CNTs), numerous syntheses methods have been developed during the last years, for example, the discharge between two graphite electrodes, laser ablation, hydrocarbon decomposition, and catalytic chemical vapor decomposition (CCVD) however, the most applied methods are arc discharge, laser ablation, and CVD [177-179]. 

Putz et al. 2004 08) SWCNT Laser Ablation NASA Johnson Space Center Purified In situ polymerization CNT Loading levels 0.0001 to 0.014 wt% Bulk Composites Addition of 0.014 wt% SWCNT increased low temperature modulus by 10% beyond that of pure PMMA. ... 

The synthesis of CNTs is reeeiving considerable interest and the main goal is to obtain large scale produetion of highly pure CNTs. There are three basic methods for synthesis of SWCNTs and MWCNTs eleetrical arch discharge, laser ablation (laser vaporization) and ehemical vapor deposition (CVD) (or catalytic decomposition of hydrocarbons) [1,7, 9,10, 25,26],... 

CNTs are generally produced using three main techniques arc discharge, laser ablation, and chemical vapor deposition. Each technique can be modified to suit the specific research purpose. 

Synthesis of CNTs Arc Discharge, Laser Ablation, Chemicai Vapor Deposition... 

CNTs can be first synthesized by arc discharge, laser ablation, and chemical vapor decomposition. CNTs are dispersed in a polymer matrix by melt blending under a high temperature and high shear force, which is also compatible with current industrial practices (Moniruzzaman and Winey, 2006). Melt blending is simple and useful for thermoplastic polymers, such as, polyethylene, polypropylene, polycarbonate, poly(methyl methacrylate)... 

CNTs find applications in the areas such as micro electronics, field emission displays. X-ray sources and gas sensors. Single waUed and multi-waUed CNTs can be grown using high pressure arcs, laser ablation and chemical vapour deposition. 

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