Nano Presentation Tinu-carbon Nano Tubes

7/28/2019 Nano Presentation Tinu-carbon Nano Tubes

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Presented byTinu Valsa PaulRoll No: 17S 3 M Tech (CPC)


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Introduction

Carbon nanotubes,composed of interlocking carbonatoms, are 1000times thinner thanan average humanhair but can be

200 times stronger than steel.

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1. Single Wall CNT (SWCNT)Can be metallic or semiconducting depending onthe way the tube is rolled up.

2. Multiple Wall CNT (MWCNT) 4


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Single Wall CNTSingle-walled carbon nanotubes (SWNTs) arenanometer-diameter cylinders consisting of asingle graphene sheet wrapped up to form atube.

When viewed with a transmission electronmicroscope single walled nanotubes appear astwo planes.

To obtain SW tubes there needs to be acatalyst involved which facilitates the growth.Typically the catalyst particles are small metal

nanoparticles, e.g. Fe or Co or Ni. 5


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Typically have a diameter of close to 1 nm.

Without the catalyst the SW nanotube enddoes not stay open during growth, but wouldclose spontaneously (i.e. the tube would never grow long but just be a fullerene).They can be twisted, flattened, and bent intosmall circles or around sharp bends withoutbreaking.

Applications :- Field-emission displays,Nanocomposite materials, Nanosensors andlogic elements.

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Multiple Wall CNT

Multi-wall nanotubes can appear either in theform of a coaxial assembly of SWNT similar toa coaxial cable, or as a single sheet of graphiterolled into the shape of a scroll.The diameters of MWNT are typically in therange of 5 nm to 50 nm. The interlayer distancein MWNT is close to the distance betweengraphene layers in graphite.MWNT are easier to produce in high volumequantities than SWNT.

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Each part of the MW tubes are single-walledtubes, with same kind of structure and chiralityas a SW tube. The chirality of one tube neednot be correlated with that of others.MW tubes can easily be tens or hundreds of microns long.MW tubes can grow by themselves.

When viewed with a transmission electronmicroscope multi walled nanotubes can beseen as a series of parallel lines.

Applications :- Capacitors Super capacitors,Batteries. 8


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Single Wall CNT

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Multiple Wall CNT

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Electronic Properties

Nanotubes have distinctly different electronicproperties depending on the chirality.Early predictions was that depending on structurethey can be metallic or semiconducting.

Armchair tubes are always metallic, others can besemiconducting or metallic.The presence of defects on the body of the tubecan alter the electronic structure and can makeregions of specific electronic properties. Sonanoscopic device structures can be made within

one tube itself. 12


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Band gap varies depending on tube indices.The density states show a distinct band gap inthe (10,10) tube(semi-conducting), while noband gap exists in (12,8) tube. Gaplessconduction is possible in this tube, making itmetallic.Band-gap is determined by the diameter of thetube:For tiny band-gap tube:

For large band-gap tube:

2/ 1 R E g

R E g / 1

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Electronic band structure is determined bysymmetry:n = m: Metaln-m = 3j (j non-zero integer): Tiny band-gap

semiconductor

Else: Large band-gap semiconductor.

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Transport Properties

The band gap of nanotubes vary from 0.2-1.2 eV.The band gap varies along the tube body andreaches minimum value at the tube ends.this isdue to the presence of localized defects at theends due to the extra states.Large contact resistance.The conductive behavior of MWNT is consistentwith weak 2-dimensional localization of carriers.In SWNT conduction occurs through discreteelectronic states that are coherent between the

electrical contacts. 15


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Mechanical Properties

Carbon-carbon bonds are one of the strongestbond in nature.

Carbon nanotube is composed of perfectarrangement of these bonds.

Nanotubes are ultimate high strength carbonfibers.

i.e. Strong like Steel16


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Light like Aluminium

Extremely high Youngs modulus in the rangeof 1-5 Tpa.

Material Youngs modulus ( GPa)

Carbon nanotubes 1250

Carbon fibers 425 (max.)

High strength steel 200

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Has the ability to withstand extreme strainin tension(upto 40%). The tubes canrecover from severe structural distortions.Carbon nanotubes are very flexible.

i.e. Elastic like Plastic 18


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Physical Properties

Nanotubes have a high strength-to-weight ratio.Density 1.8g/cm 3 for MWNT & 0.8g/cm 3 for SWNT.So useful for lightweight applications.

Highly resistant to chemical attack.Difficult to oxidize and onset of oxidation is 100 0Chigher than that of carbon fibers. So temperatureis not a limitation in practical applications of CNT.The surface area is of the order of 10-20m 2/g.

Expected to have high thermal conductivity andthe value increases with decrease in diameter.

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Electronic Applications

Used as electrical conductors. A nanotube based single molecule field effecttransistor has been built already.Commertcial application of nanotube CNT-basedfield emission displays.

Nanotube tips can be used as nanoprobes.

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The joining of two carbonNanotubes with different

electrical properties to forma diode has been proposed.

CNT based Ultra-Capacitors have high energy density,Capacitances up to 5000 Fcan be achieved.

CNT based Transistors workat room temperature and arecapable of fast digital switchingusing a Single Electron. 22


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Nanotubes in AV Technology

Carbon nanotubes arebeing used to developflat screen televisionswith higher resolutionthan the human eyecan detect

Your next TV screencould be thin, ultra-light and foldable

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Other Applications

Nanotube based flow sensors and filters are alsomade.Researches proved the ability of carbonnonotubes to store hydrogen. Storage occurs bothin between and inside the nanotube bundles. Theamount of hydrogen stored is comparable to that

of storage capacity of metal hydrides.2 H2(g) + O 2(g) 2 H2O (l) + energyThe application of this kind of storage is importantfor fuel cell applications for automobiles wherestora e of h dro en is a critical factor. 24


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Worlds Smallest motor.The NANO MOTOR

CNT membranes support fluidflows at several magnitudes thanproposed in Classical FluidDynamics

CNT sponge can filter any toxicsludge from water . As CNTsponge is Hydrophobic , it absorbseverything but not water.


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Nanotubes in Efficient Solar Cells

Scientists have developedthe blackest black colour using carbon nanotubes

The carbon nanotubes arearranged like blades of grass in a lawn- they absorb nearly alllight

Use of carbon nanotubesin solar cells could vastlyimprove their efficiency

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Nanotubes in Sporting Equipment Badminton racquet manufacturer

Yonex incorporates carbonnanotubes into their cup stackcarbon nanotubes racquets(www.yonex.com )

American baseball batmanufacturer Easton Sports hasformed an alliance with ananotechnology company Zyvex to

develop baseball bats incorporatingcarbon nanotubes Tennis racquets also incorporate

carbon nanotubes.

(www.babolat.com ). 27
http://www.yonex.com/http://localhost/var/www/apps/conversion/tmp/scratch_12/Nanotubes%20In%20Sporting%20Equipmenthttp://localhost/var/www/apps/conversion/tmp/scratch_12/Nanotubes%20In%20Sporting%20Equipmenthttp://www.yonex.com/http://www.yonex.com/http://www.yonex.com/http://www.yonex.com/http://www.yonex.com/


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The Space Elevator

The Idea To create a tether from earth to some object

in a geosynchronous orbit. Objects can thencrawl up the tether into space.

Saves time and money The Problem

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

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The Space Elevator

The Solution: Carbon Nanotubes10x the tensile strengh (30GPa)

1 atm = 101.325kPA 10-30% fracture strainFurther Obstacles

Production of Nanofibers Record length 4cmInvestment Capital: $10 billion

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CNT based BUCKY PAPERS are 250 timesstronger than steel and 10 times lighter. Showspromise as vehicle & personnel armor andnext-generation electronics display.

May be used in Nano-Radio, sound can begenerated not by vibrations but byThermoacoustics Principle.

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Referenceswww.noritake-elec.com/.../nano/structu.gif

http://en.wikipedia.org/wiki/Carbon_nanotube

academic.pgcc.edu/~ssinex/nanotubes/graphene.gif

http://www.ipt.arc.nasa.gov T.Pradeep,Nano The Essentials:Understandingnano science and nanotechnology,Mc -Graw Hill

Edition 33
http://en.wikipedia.org/wiki/Carbon_nanotubehttp://www.ipt.arc.nasa.gov/http://www.ipt.arc.nasa.gov/http://en.wikipedia.org/wiki/Carbon_nanotube


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Nano Presentation Tinu-carbon Nano Tubes

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