hello readers, today we discuss the What is carbon nanotubes(CNTs)? , applications and properties of carbon nanotubes.
The more interesting nanostructures with large application potential are carbon nanotubes (CNTs).
In 1991, Sumio Iijima discovered CNTs. CNTs are also known as buckytubes. They are allotropes Of carbon with a cylindrical nanostructure.
What is a Carbon Nanotube(CNT)?
A carbon nanotube is a cylindrical rolled up sheet of graphene mostly closed at the ends. the rolled structure is a single molecule. Each single molecule nanotube is made up of a hexagonal network structure of covalently bonded carbon atoms. Their hexagonal structure gives them great tensile strength and elastic properties.
Nanotubes are members of the fullerene structural family, which also includes the spherical buckyballs. The ends of a nanotube may be capped with a hemisphere of the buckyball structure These are simply called as “caps” or “end caps”. Caps contain six pentagons (half the number in C12 fullerene) and the different number of hexagons so that they can fit on the tubes properly. Carbon nanotubes are categorized as, Single-Walled Carbon Nanotubes (SWCNTs) and Multi-Walled Carbon Nanotubes (MWCNTs), i.e., tubes with many concentric cylinders of graphite).
An SWCNT can have a diameter of 2nm and a length of 100 µm, making it effectively a dimensional structure called a nanowire.
Both SWCNT and MWCNT have their own range of applications.
PROPERTIES OF CARBON NANOTUBES:-
- The carbon nanotubes have extremely low resistance.
- The conductivity of nanotubes is a function of diameter.
- CNTs are metallic or semiconducting depending on the diameter and chirality of the tube
- Metallic nanotubes can carry an electric current which is more than 1000 times greater than metal copper.
- CNTs have a high thermal conductivity which increases with the decrease in diameter.
- CNTs melting temperature is three times higher than the melting point of copper.
- CNTs are the strongest and stiffest material in terms of flexible strength and elastic modulus respectively.
- The tensile strength is more than 20 times greater than steel.
- CNTs have the ability to withstand the extreme strain.
- Nanotubes are highly resistant to chemical attack.
- Nanotubes have a high strength to weight ratio. This is indeed useful for the light-weight application.
APPLICATION OF CARBON NANOTUBES:-
1. CNTs find a wide range of application in many different fields. Few of them are listed below.
2. CNTs are used in constructing nanoscale electronic devices.
3. CNTs are used in battery electrodes, electrical devices, reinforcing fibres which make stronger composites.
4. The electron emission concept of CNTs is used in developing a flat-panel display.
5. Based on the electron emission effect of CNTs, vacuum tube lamps that are bright as conventional light bulbs with longer life and more efficiency can be produced.
6. Semiconducting CNTs are used as switching devices and display devices.
7. Chiral semiconducting carbon nanotubes are used as a sensitive detector of various gases.
8. CNTs are used in battery technology to design fuel cells.
9. Nanotube tips can be used as nanoprobes.
10. Nanotubes serve as the catalyst for some chemical reaction.
11. The CNTs can be used to build tiny electronic circuits which are almost 1000 times smaller for today’s technology.
12. CNTs are used as interconnects in chip due to their extremely low resistance.
13. A plastic composite of CNTs is used in designing a light-weight shielding material for electromagnetic radiation.
Electron emission – When a small electric field is applied parallel to the axis of nanotube electrons are emitted at a very high rate from the ends of the tube. This is called electron emission effect.
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