IndexTypes of carbon nanotubesProperties of carbon nanotubesMechanical propertiesSynthesisLaser ablationChemical vapor depositionApplications of carbon nanotubesCNTs are long cylinders of covalently bonded carbon atoms that possess extraordinary electronic and mechanical properties. There are two basic types of CNTs: single-walled carbon nanotubes (SWCNTs) which are the fundamental cylindrical structure, and multi-walled carbon nanotubes (MWCNTs) which are made up of coaxial cylinders, with layer spacing close to that of the distance between layers in graphite. (0.34 nm). These cylindrical structures are only a few nanometers in diameter, but the cylinder can be tens of microns long, with most of the ends capped by half a fullerene molecule. CNTs can be prepared using three methods that include DC arc discharge, laser ablation, and chemical vapor deposition (CVD). Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Types of Carbon Nanotubes SWCNTs are made up of a single layer of carbon. May have a greater tendency to line up in orderly bundles. MWCNTs are made up of two or more layers of carbon. Tends to form unordered 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, stiffness, toughness and low density. Mechanical properties The strength of the bond CC brings great interest in the mechanical properties of nanotubes. In theory, these should be stiffer than any other known substance. The Young's modulus of single-walled carbon nanotubes (SWCNTs) can be up to 2.8-3.6 TPa and 1.7-2.4 TPa for multi-walled carbon nanotubes (MWCNTs), which is approximately 10 times higher than that of steel, the strongest known metal alloy. Electrical Properties The nanometer size of CNTs, combined 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 make a good electrical conductor. Some nanotubes have higher conductivity than copper, while others behave more like silicon. Theoretically, metallic nanotubes with electrical conductivity between 105 and 106 S/m can carry an electric current density of 4 × 109 A/cm2, which is more than 1000 times greater than metallic copper, and thus can be used as a fine electron gun for low weight display.SynthesisD.c Arc DischargeThe carbon arc discharge method, initially used to produce C60 fullerenes, is the most common and perhaps most simple to produce CNT. But this technique produces graphitic impurities such as carbon soot containing amorphous carbon, anions and fullerenes. 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 furnace tube at 1200º C. When the target is ablated, the inert gas is passed through the chamber carrying the grown nanotubes onto a cold finger for collection. This method mainly produces SWCNTs in the form of ropes. Chemical vapor deposition In this process, a mixture of hydrocarbon, metal catalyst and inert gas is introduced into the reaction chamber. This technique offers greater control over the length and structure of the nanotubes produced compared to arc and laser methods. This process can also be scaled up to produce industrial quantities of CNTs. Applications.