Carbon nanotube

CARBON NANOTUBECARBON NANOTUBE

Monday 28 July 2014 1

KUMOD KUMAR JHAElectronics & Communication Engineering6th Semester,BT11EC017

OUTLINE

Introduction to CNT. Classification. Properties. Synthesis. Applications. Drawbacks. Conclusion.



Allotropes of carbon with a cylindrical nanostructure.Allotropes of carbon with a cylindrical nanostructure.

Member of the fullerene structural family .Member of the fullerene structural family .

Hexagonally arrangement of carbon atoms.Hexagonally arrangement of carbon atoms.

Sp2 hybridised bonds.Sp2 hybridised bonds.

INTRODUCTION TO CNT

CLASSIFICATIONCLASSIFICATION


CONDUCTIVITY CHIRALITY LAYERS

ON THE BASIS OF

1.

2.

1.

2.

3.

1.

2.

CONT...CONT...


Conductance is mainly affected by Chirality of CNT. Twisting can transform a m-CNT to s-CNT. Different types of nanotubes are determined by chiral vector (m,n)

and vector equation R=na1+ma2. Wrapping angle (b/w arm chair line and R) = 0° Arm chair CNT =30° Zigzag CNT 0° < < 30° Chiral CNT An arm chair CNT is always metallic in nature.

SWcNT - Single atomic layer thick sheet of graphite rolled in seamless cylinder.

MWcNT - Multiple rolled layers (concentric tubes) of graphite.

E

PROPERTIESPROPERTIES

SizeSize: : Varies from 0.8-1.6 nm in diameter .Varies from 0.8-1.6 nm in diameter .

DensityDensity: 1.33-1.40 gram/: 1.33-1.40 gram/cmcm33.(Al-2.7 gm/cm3).(Al-2.7 gm/cm3)

ElectricalElectrical PropertyProperty: : The current carrying capacity of SWCNT is found to be 1 Billion AmpereThe current carrying capacity of SWCNT is found to be 1 Billion Ampere//cmcm2. 2.

Cu wire burn at 1 Million A/Cu wire burn at 1 Million A/cmcm22..

ResilienceResilience: Can be bent at larger angle and restraightened without damage.: Can be bent at larger angle and restraightened without damage.

StrengthStrength: Strongest & stiffest known material in terms of tensile strength and elastic modulus respectively. Tested : Strongest & stiffest known material in terms of tensile strength and elastic modulus respectively. Tested

MWCNT Tensile Strength- 63 GPa(billion Pascal),Elastic modulus-1 Tpa. High Strength steel breaks at about 2 MWCNT Tensile Strength- 63 GPa(billion Pascal),Elastic modulus-1 Tpa. High Strength steel breaks at about 2

GPa.GPa.

ThermalThermal: Ballistic Conduction, Can transmit heat up to 6000 W/m/K at room temperature(Thermal heat : Ballistic Conduction, Can transmit heat up to 6000 W/m/K at room temperature(Thermal heat

conductivity of Cu-385 W/m/K).Temperature Stability 2800 º C(vacuum), 750 º C(air).conductivity of Cu-385 W/m/K).Temperature Stability 2800 º C(vacuum), 750 º C(air).


SYNTHESISSYNTHESIS

Arc Discharge MethodArc Discharge Method

Connect two graphite rods to a power Connect two graphite rods to a power supply, place them 1mm apart in an supply, place them 1mm apart in an enclosure containing inert gases at enclosure containing inert gases at low pressure(50 -700 mbar), and low pressure(50 -700 mbar), and throw switch at 100 amps, Carbon throw switch at 100 amps, Carbon vapourises in hot plasma and gets vapourises in hot plasma and gets deposited on other electrode. From it deposited on other electrode. From it CNT is separated.CNT is separated.

Producing CNT in high yieldProducing CNT in high yield

Both SWCNT and MWCNT can be Both SWCNT and MWCNT can be produced.produced.

The CNT produced is The CNT produced is short(short(ππm),randomly oriented.m),randomly oriented.

The defects depends on uniformity of The defects depends on uniformity of plasma arc.plasma arc.

Chemical Vapour DepositionChemical Vapour Deposition

A Pulsed Laser vapourises A Pulsed Laser vapourises graphite target in high graphite target in high temperature reactor having inert temperature reactor having inert gas blended into chamber.CNT gas blended into chamber.CNT

develops at cooler portion of develops at cooler portion of reactor as vapourised carbon reactor as vapourised carbon condenses.condenses.

Cleanest CNT Produced.Cleanest CNT Produced.

SWCNT is produced with SWCNT is produced with

controllable diameter.controllable diameter.

Costlier than other two methods.Costlier than other two methods.

Laser AblationLaser Ablation

Place substrate in oven, heat to 600 ˚C, Place substrate in oven, heat to 600 ˚C, and slowly add a carbon-bearing gas and slowly add a carbon-bearing gas such as methane. As gas decomposes such as methane. As gas decomposes it frees up carbon atoms, which it frees up carbon atoms, which recombine in the form of CNT.recombine in the form of CNT.

Maximum length can be achieved.Maximum length can be achieved.

Normally MWCNT produced.Normally MWCNT produced.

Relatively lower cost of production.Relatively lower cost of production.

Under research for Scaling up to Under research for Scaling up to industrial level.industrial level.


APPLICATIONAPPLICATION

Nano materialsNano materials..

Space ElevatorSpace Elevator

Nano systems.Nano systems.

Nano electronics.Nano electronics.


NANO ELECTRONICS

What is technology? Moore’s law. Scaling problems.

CNT TECHNOLOGYCNT TECHNOLOGY

First intramolecular transistor made.First intramolecular transistor made.

Joining two CNTs with different electrical properties to form diode has been Joining two CNTs with different electrical properties to form diode has been

proposed.proposed.

Ballistic transport enables Lower operating voltage Higher ON-current .Ballistic transport enables Lower operating voltage Higher ON-current .

Ultra-thin body enables aggressive device scaling , Excellent switching (gate Ultra-thin body enables aggressive device scaling , Excellent switching (gate

electrostatics) electrostatics)

Low power performance.Low power performance.


DRAWBACKSDRAWBACKS

Production Cost.Production Cost.

Problems like controlling length,chirality,purification and separation is still not Problems like controlling length,chirality,purification and separation is still not

resolved.resolved.

Production at industrial level still an issue.Production at industrial level still an issue.

Defects such as atomic vacancies, stone well defects can change the entire property Defects such as atomic vacancies, stone well defects can change the entire property

of CNT.of CNT.

Extremely small so difficult to work with.Extremely small so difficult to work with.

Toxic in nature, can cause inflammatory.Toxic in nature, can cause inflammatory.

How working still a mystery.How working still a mystery.


CONCLUSIONCONCLUSION

Nanotechnology is predicted to spark a series of industrial revolutions.Nanotechnology is predicted to spark a series of industrial revolutions.

Wide application areas.Wide application areas.

Outstanding Properties.Outstanding Properties.

Lack of synthesis process.Lack of synthesis process.

The next big thing is very small.The next big thing is very small.


Thank you

Technology

Carbon nanotube