Journal of Nanomaterials and Devices

Carbon Nanotubes

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Carbon Nanotubes (CNTs) are the allotrope of Carbon with a cylindrical nanostructure. CNTs are smooth, tube-shaped fibers. They are made from a single flat layer of carbon atoms, rolled into a cylinder. Their thickness varies between 0.7 to 50 nanometers, and their length is varies between 10 to 100 microns. These Nanotubes are the members of the Fullerene structural family.

There are two types of carbon nanotubes i.e. Single-Walled Nanotubes and Multi-Walled Nanotubes. Single-walled nanotubes are of 1 nanometer with Bandgap of 0-2 eV, made by rolling a single layer of graphene into a seamless cylinder. Multi-walled nanotubes are made of multiple layers of rolled graphite whose outer diameter is about 20 nanometers and the inner diameter is around 3 nanometers.

There are three different techniques to produce nanotubes. These are the Arc Discharge method, Laser Ablation method, and Chemical Vapour Deposition (CVD) method. CVD is the most common way to make carbon nanotubes. In this method, gases like methane, carbon monoxide, and acetylene are used as Carbon source.

Carbon Nanotubes Electrical Conductivity is six orders of magnitude higher than copper (Cu) & it has also very high current carrying capacity. The heat flow in carbon nanotubes is very high in the axial direction and very low in the lateral direction.

The benefits of carbon nanotubes are that they are extremely strong, can carry electric current very quickly, are very tiny but work at high speed, have low power consumption, the velocity of electron in CNTs is equal to velocity of light.

CNTs are mainly used in electronics. They are used to make flat screen displays, wires, and tiny switches called transistors. They are also used in super capacitors, lithium batteries, and to store hydrogen for energy. In the medical field, CNTs are used to make artificial muscles, to help read DNA, and to create sensors that can detect diseases.