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