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CARBON NANOTUBES
INTRODUCTION
STRUCTURE
Folded version of two dimensional graphite sheets
Depending on the dimension of the graphite sheet and type of folding, different types can be created. Eg :SWNTS, MWNT’S
Sidewalls consist of only hexagonal carbon rings
TYPES OF CNT’S
There are two types of CNT’S
1. Single walled Nanotubes(SWNT’S)
2.Multi walled Nanotubes (MWNT’S)
1.SINGLE WALLED NANOTUBES
Most single-walled nanotubes (SWNT) have a diameter of close to 1 nanometer, with a tube length that can be many millions of times longer.
Single-walled nanotubes are an important variety of carbon nanotube because they exhibit electric properties that are not shared by the multi-walled carbon nanotube (MWNT) variants.
MULTIWALLED NANOTUBES
Multi-walled nanotubes (MWNT) consist of multiple rolled layers (concentric tubes) of graphene.
MWNTs are zero-gap metals.
SYNTHISIS of CNT’S
There are three techniques to produced nanotubes
Arc discharge method
Laser Ablation method
Chemical Vapor Deposition (CVD) Method
a)Arc discharge method
c)Chemical Vapor Deposition
CNT PROPERTIES
a)Electronic and Electrical property
Advantages
Ultra Strength
Fast electron conductivity
Very small with high frequency and low power consumption.
Velocity of electrons in carbon nanotubes is equal to velocity of light.
Mobility of electron in carbon nanotubes is 200 times that of silicon
APPLICATIONS
1.IN ELECTRONICS
A) Flat Panel Display
Low power consumptio, High brightness
Wide viewing angle
Fast response rate
B) As Conductors and Transistors
C) Ultracapacitors:
High surface area to mass ratio of graphene.
Greater energy storage density than currently available.
Biological
Manufacture of Artificial muscles
Auto parts
60 percent of cars produced today now have fuel lines made with carbon nanotubes.
The carbon nanotubes inside the fuel lines are intended to reduce the risk of explosions by inhibiting static electricity.
Sporting Equipment
Carbon nanotubes have already been added to sports equipment such as bats, bicycles, golf clubs, and hockey sticks in order to impart more strength and absorb vibrations.
Limitations of CNT’S
High-Quality nanotubes can only be produced in very limited quantities -commercial nanotube soot costs 10 times as much as gold!
Since these particles are very small, problems can actually arise from the inhalation of these minute particles.
FUTURE ENHANCEMENTS
In future carbon nanotubes replaces carbon fiber.
It is also used in VLSI interconnections and in water purification.
It replaces silicon based diodes and transisters in future.
LIST OF CARBON NANOTUBE SUPPLIERS
NANOSHEL(INDIA)
BUCKYUSA (USA)
ARKEMA (FRANCE)
NIKKISO CO. LTD. (JAPAN)
CARBON DESIGNS, INC. (USA)
BAYER MATERIAL SCIENCE AG (GERMANY)
CONCLUSION
Carbon nanotubes are the next step in miniaturizing electronic circuits, replacing silicon transistors and diodes, which are fast reaching the theoretical limits of size and speed of operation.
Using CNTs, nanochips can be made with entire circuits on it. Ideal diodes can be made from CNTs, resulting in highly efficient electronic circuits. Further, CNTs have a number of other uses other than in the electronic industry, as seen here.