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Essay / What are carbon nanotubes (CNTs) possess extraordinary electronic and mechanical properties. There are two basic types of CNTs: single-walled carbon nanotubes (SWCNTs) which make up the fundamental cylindrical structure and multi-walled carbon nanotubes (MWCNTs) which are made of coaxial cylinders, having an interlayer spacing close to that of the interlayer distance in graphite. (0.34nm). These cylindrical structures are only a few nanometers in diameter, but the cylinder can be tens of microns long, with most of its ends capped with half a fullerene molecule. CNTs can be prepared using three methods, including continuous arc discharge, laser ablation, and chemical vapor deposition (CVD). Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Types of Carbon Nanotubes SWCNTs are made of a single layer of carbon. It may have a greater tendency to line up in orderly bundles. MWCNTs are made of two or more layers of carbon. It tends to form messy clumps. Properties of Carbon Nanotubes Carbon nanotubes have exceptionally high material properties, very close to their theoretical limits, such as electrical and thermal conductivity, strength, rigidity, toughness and low density. Mechanical properties The strength of the CC bond gives great interest to the mechanical properties of nanotubes. Theoretically, these should be more rigid than any other known substance. The Young's modulus of single-walled carbon nanotubes (SWCNTs) can reach 2.8-3.6 TPa and 1.7-2.4 TPa for multi-walled carbon nanotubes (MWCNTs), which is about 10 times greater than that of steel, the strongest metal alloy known. Electrical PropertiesThe nanoscale dimensions of CNTs, along with the unique electronic structure of a graphene sheet, make the electronic properties of these one-dimensional (1D) structures extraordinary. The one-dimensional structure of CNTs helps them to be a good electrical conductor. Some nanotubes have conductivities higher than that of copper, while others behave more like silicon. Theoretically, metal nanotubes with an electrical conductivity of 105 to 106 S/m can carry an electrical current density of 4 × 109 A/cm2, more than 1000 times. larger than metallic copper and can therefore be used as a fine electron gun for low-weight displays. Synthesis D.c arc dischargeThe carbon arc discharge method, originally used to produce C60 fullerenes, is the most common and perhaps simplest way to produce CNTs. But this technique produces graphitic impurities such as carbon soot containing amorphous carbon, anions and fullerens. Laser Ablation Laser ablation uses an intense laser pulse to vaporize a carbon target, which also contains a small amount of metals such as nickel and cobalt and is placed in a tube. oven at 1200ºC. As the target is ablated, an inert gas passes through the chamber carrying the grown nanotubes onto a cold finger for collection. This method mainly produces SWCNTs in the form of strings. Chemical vapor deposition In this process, a mixture of hydrocarbons, metal catalyst.
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