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CARBON NANOTUBES
By: HIMANSHU TYAGI
CARBON NANOTUBES
BY: HIMANSHU TYAGI ECE- 3rd YEAR Roll No. : 1122231032
What are carbon nanotubes
2
CNT: Rolling-up a graphene sheet to form a tube
Schematic of a CNT
DID YOU KNOW?
Carbon nanotubes, composed of interlocking carbon atoms, are 1000x thinner than an average human hair – but can be 200x stronger than steel.
Discovery of carbon nano tubes #1952 Radushkevich and Lukyanovich publish a paper in the Soviet Journal of Physical Chemistry showing hollow graphitic carbon fibers that are 50 nanometers in diameter.
#1979John Abrahamson presented evidence of carbon nanotubes at the 14th Biennial Conference of Carbon at Pennsylvania State University.
#1981A group of Soviet scientists published the results of chemical and structural characterization of carbon nanoparticles produced by a thermocatalytical disproportionation of carbon monoxide.
#1991Nanotubes discovered in the soot of arc discharge at NEC, by Japanese researcher Sumio Iijima.
Types of CNTs
Single Wall CNT (SWCNT)
Multiple Wall CNT (MWCNT)
Can be metallic or semiconducting depending on their geometry.
SINGLE WALLED NANOTUBES
Diameter :- 1 nanometer
Band gap :- 0-2ev
A one atom thick layer of graphene into seamless cylinder .
Their electrical conductivity can show metallic or semiconducting behaviour.
A scanning tunnelling microscopy image of SWNT
MULTI WALLED NANOTUBES
Multi-walled nanotubes (MWNT) consist of multiple rolled layers (concentric tubes) of graphene.
Interlayer distance :- 3.4 Å
To describe structure of MWNT there are two models:-
1. Russian doll model
2. Parchment model
SWNT’s MWNT’s
SYNTHESIS OF CARBON NANOTUBES
There are three methods using which we can produce carbon nanotubes.
1. ARC DISCHARGE METHOD :-
2. LASER ABLATION :-
3. CHEMICAL VAPOR DEPOSITION (CVD) :-
Fiber material Specific Density
Young's modulus(Tpa)
Strength (Gpa)
Strain at break(%)
Carbon Nanotube 1.3 – 2 1 10 – 60 10HS Steel 7.8 0.2 4.1 <10Carbon fiber-PAN 1.7 – 2 0.2 – 0.6 1.7 – 5 0.3 – 2.4Carbon fiber-Pitch 2 – 2.2 0.4 – 0.96 2.2 – 3.3 0.27 – 0.6E/s-Glass 2.5 0.07 – 0.08 2.4 – 4.5 4.8Kevlar-49 1.4 0.13 3.6 – 4.1 2.8
Mechanical Properties
Properties of Conductive Materials
Material Thermal conductivity Electrical conductivity
Carbon Nanotube > 3000 10^6 – 10^7
Copper 400 6 x 10^7
Carbon fiber-Pitch 1000 2 - 8.5 x 10^6
Carbon fiber-PAN 8 - 105 6.5 - 14 x 10^6
PROBLEMS RELATED TO CARBON NANOTUBES
Toxicity:-
Under some conditions, nanotubes can cross membrane barriers, which suggests that if raw materials reach the organs they can induce harmful effects such as inflammatory and fibrotic reactions.
Crystallographic defect:-
As with any material, the existence of a crystallographic defect affects the material properties. Defects can occur in the form of atomic vacancies.
Electrical• Field emission in Displays• Application in electrodes, capacitors• Used in transistors• Nanocomputers
Energy storage• Lithium batteries• Hydrogen storage
Biological• Cancer treatment• DNA sequencing
Applications
Fig : I-POD NANO
Fig: TRANSFORMATION OF TRANSISTORS FROM HUGE SIZE TO NANO-CIRCUITS
Fig: Intel’s 32nm Nehalem chip architecture
Fig: Paper battery
Future Works
• Difficult control of CNT– Diameter– Chirality– Density– placement
• Improve resistivity of transparent SWNT films so that they are better than equally transparent, optimally doped ITO coatings.
• Further price reductions of SWNT needed
In Conclusion…
• There are many unique properties• Further investigation of toxicity is needed• There are many ways to synthesis• Method of synthesis depends on financial
needs and amount of product desired• There are many exciting applications of carbon
nanotubes due to their outstanding & novel properties
REFERENCE
EN.WIKIPEDIA.ORG/WIKI/CARBONNANOTUBES
WWW.SCIENCEDAILY.COM
HOW STUFF WORKS – WWW.HOWSTUFFWORKS.COM
IMAGES.GOOGLE.CO.IN/IMAGES
WWW.UNDERSTANDINGNANO.COM/NANOTUBES-CARBON.HTML
WWW.NANOCYL.COM › CNT EXPERTISE CENTRE
WWW.PA.MSU.EDU/CMP/CSC/NANOTUBE.HTML