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Outline :

• Allotropes of carbon with a cylindrical structure

• Can be capped on the ends with buckyballs or open ended

• Composed entirely of sp2 bonds

What are they?

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Family Background (Hierarchy)

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Geometry Rollup Vector

(n,m) n-m=3k

Chiral Angle tan(θ) =

√3m/(2√(n2+m2+nm))

Arm Chair (n,n), θ=90 ○

Zig-zag (n,0), θ=0 ○

Chiral, 0○< θ<90 ○

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Geometry….

•N-m=3k 6CARBON NANO TUBES

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Four Ways to SynthesizeCarbon Nanotubes

Arc Discharge Laser Ablation Chemical Vapor

Deposition (CVD)

Ball Millinghttp://students.chem.tue.nl/ifp03/synthesis.html

Chemical Vapor Deposition

Carbon is in the gas phase Energy source transfers

energy to carbon molecule Common Carbon Gases

Methane Carbon monoxide Acetylene (C2H2)

http://neurophilosophy.files.wordpress.com/2006/08/multiwall-large.jpg

Chemical Vapor Deposition

Carbon is in the gas phase Energy source transfers energy

to carbon molecule Usually a silicon plate coated

with iron particles is the substrate.

Common Carbon Gases Methane Carbon monoxide Acetylene

Chemical Vapor Deposition

After energy transfer, the carbon molecule binds to the substrate

Temperature between ~1300⁰F

Carbon nanotubes stick to each other due to Vander walls force.

When tubes are extracted , cling on to each other and pull each other out of substrate

Yield is usually about 30% One of the most common

methods of carbon nanotube synthesis

Chemical Vapor Deposition

Advantages

Disadvantages

Easy to increase scale to industrial production

Large length Simple to perform Pure product

http://endomoribu.shinshu-u.ac.jp/research/cnt/images/cat_cnt.jpg

• Defects are common

Unique properties Material of the future Seemingly infinite

applications Possible health issues

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Why Should We Care?

Carbon nanotubes have the strongest tensile strength of any material known.

It also has the highest modulus of elasticity.

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Strength Properties

Material Young's Modulus (TPa)

Tensile Strength (GPa)

Elongation at Break (%)

SWNT ~1 (from 1 to 5) 13-53E 16

Armchair SWNT 0.94T 126.2T 23.1

Zigzag SWNT 0.94T 94.5T 15.6-17.5

Chiral SWNT 0.92

MWNT 0.8-0.9E 150

Stainless Steel ~0.2 ~0.65-1 15-50

Kevlar ~0.15 ~3.5 ~2

KevlarT 0.25 29.6

Stress-strain response of a CNT under tensile loading

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Nanotubes: how they conduct

In theory, metallic nanotubes can carry an electrical current density of 4×109 A/cm2 Attach metal electrodes

Can be connected to single tube or bundle of several hundred tubes Drop tubes onto electrodes (a) Deposit tubes on substrate, locate with scanning electron microscope, attach leads

to tubes using lithography (b) Advanced techniques

Growing tubes between electrodes Attaching tubes to surface in controllable fashion using electrostatic or chemical

forces.

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Coating and Films

CNT-based transparent conducting films Alternative to expensive indium tin oxide (ITO) Flexible, and not brittle Application in

Displays Touch screen devices photovolatics

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Coating ,Transparent conductors and Films

CNT conductors can be deposited from solution Slot-die coating Ultrasonic spraying

Can be patterned by economic nonlithographic methods Recent developments have allowed for

SWNT films with 90% transparency Sheet resistivity of 100 ohm per square Adequate applications such as CNT thin-film heaters like defrosting

windows or sidewalks

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Energy Storage (supercapacitors)

Study on packaged cells utilizing forest-grown SWNTs revealed remarkable performance

16 Wh kg-1 energy density 10 kW kg-1 power density 16 year lifetime forecast

The only drawback is the high cost of SWNTs

FUTURE WORK –Super conductors

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Future Workso Future Electrical

Transmission.o Will cut the cost of Silver

required.

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SEM image of the smallest working gear(CNT+nylon)

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• The Idea– To create a tether from earth to some

object in a geosynchronous orbit. Objects can then crawl up the tether into space.

– Saves time and money• The Problem

– 62,000-miles (100,000-kilometers) – 20+ tons

The Space Elevator

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The Space Elevator

Hybrid Power Generation

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o Charging your electric car within seconds using devices made of carbon nanotubes!!!!Ex:

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More applications….

Toxicity Research has shown

:- In rodents, carbon

nanotubes have been found to cause several lung issues.

The needle-like shape of the fibers is similar to that of asbestos.

http://www.phy.mtu.edu/newsletter/research/FatNanotubes.jpg

In Conclusion…

There are many unique properties Inhaling can cause toxic-reaction There are many ways to synthesize There are many exciting

applications of carbon nanotubes

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In Conclusion…

Sources

M. S. DRESSELHAUS, G. DRESSELHAUS, and R. SAITO. Carbon 33, 7 (1995)

R. Martel, T. Schmidt, H. R. Shea, T. Hertel, and Ph. Avourisa. App. Phys. Lett. 73, 17 (1998)

Sander J. Tans, Michel H. Devoret et al. Nature 386, 474-477 (1997)

Jean-Paul Salvetat et al. Phys. Rev. Lett. 82, 5 (1999) MICHAEL S. ARNOLD et al. Nature Nanotechnology 1,

60-65 (2006) www.noritake-elec.com/.../nano/structu.gif academic.pgcc.edu/~ssinex/nanotubes/graphene.gif nano.gtri.gatech.edu/Images/MISC/figure4.gif

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for bearing our presentation…