carbon nanotube applications in engg

8/3/2019 Carbon Nanotube Applications in Engg

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CARBON NANOTUBEAPPLICATIONS IN ENGG

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CONTENTS

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INTRODUCTION

PROPERTIES OF CARBON NANOTUBES

APPLICATIONS CONCLUSION

REFERENCES


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INTRODUCTION

A carbon nanotube is a sheet of carbon atoms joined in

a pattern of hexagons and rolled into cylinder.

They are several micrometers in length and a few

nanometers in diameter, resulting in a larger length-to-

diameter ratio of up to 132,000,000:1.

Nanotubes are members of the fullerene structural

family, which also includes the spherical buckyballs.

The ends of a nanotube might be open or capped with a

hemisphere of the buckyball structure.

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TYPES OF CNTs

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Figure 1: (a) Armchair,(b) zigzag, and (c) chiral shaped single Figure 2: Multi-wall carbon nanotubes


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PROPERTIES OF CARBON NANOTUBES

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Properties Numerical valuesTypical diameter 1-2nm

Typical length 100-1000nm

Resistivity at 300k 10-4-10-3 cm(metallic)

10 cm (semiconductor)

Current density 107-108A cm-2

Thermal conductivity at 300k 20-300Wm-1K-1

Thermal stability 2800 C (vacuum )

750 C (air)

Elastic modulus 1000-3000GPa, harder

than steel

Table 1: Properties of carbon nanotubes


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APPLICATIONS

PLANAR MICRO SUPERCAPACITOR

A supercapacitor is a charge storage device composed of

two electrodes with electrolyte in between.

1-Butyl-3-methylimidazoliumtetrafluoro-borate

([BMIM] [BF4]) with its high breakdown voltage

of3V was used as the electrolyte

PDMS cap limit the flow of electrolyte

within a fixed 5mmx7mm CNT region.

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Figure 3: Schematic of planar micro

supercapacitor using aligned, 3DCNT forest electrode


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PRINCIPAL OF PLANAR MICRO SUPERCAPACITOR

under a biased voltage, the positive and negative ions

in electrolyte will separate, migrate and accumulate

around the electrode surface, forming a nm-thin layer

called electro-chemical double layer (EDL) whichenhances the capacitance.

Moreover the porous electrodes maximize the EDL

phenomenon and give supercapacitors an

astonishingly high value of specific capacitance

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ADVANTAGES OF PLANAR MICRO SUPERCAPACITOR

The demonstration of the capability of "planar"

structure for supercapacitors could inspire new

architecture in circuit.

CNT-covered supercapacitor has generated a specific

capacitance of 428gf/cm2, three orders higher than

those merely using metal electrodes.

The samples show an excellent charge efficiency of

92% and a robust cycling stability.

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ELECTRONIC APPLICATIONS

Due to the miniaturization of the computers, there is an

increasing demand in increasing the number of switches in a

chip.

The metal wires with small diameter are used to do the

interconnections between the computer and switches.

A decrease in the diameter of a wire in turn increases the

resistance and hence, the wire generates heat due to the flow

of current.

CNT have smaller dimensions and low resistivity. 9


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ELECTRONIC APPLICATIONS (contd)

Field effect transistor

Figure 4: a) CNT based field effect transistor (b) Charactericstics


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ELECTRONIC APPLICATIONS (contd)

CNT switches

Parallel carbon nanotube are placed on silicon substrate .

The top array and the bottom array are perpendicular to

each other and are not in contact .

The crossing point

represents switches .

It is controlled by

passing current through

the tubes.

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Figure 5: CNT switch arrays on a silicon substrate


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ULTRA SMALL SINGLE WALLED CARBON

NANOTUBE PRESSURE SENSORS

The SWNT strain gauges are embedded between double

layer membrane of 70nm SiO2 and 70nm of Al203

These oxide layers are used to protect it from the

environment.

The SWNT is contacted in the

form of FET

The change in the resistance is

used to measure the pressure

These are more sensitive and more efficient


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CONCLUSION

The applications of CNT ensure a bright future for

these materials.

Attractive characteristics of CNTs have made

researcher to fabricate products using CNT.

Nanotubes are very user-friendly, very robust,

they can also act as excellent model systems for

learning manipulation at a nanometer scale.

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REFERENCES

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1. S.P.Basavaraju, A Text Book of Engineering Physics ,2010, 554-561

2. M. R. Srinivasan, New Age International Publishers ,

Physics for Engineers, 714-721

3. V. Rajendran, Tata Mcgraw-Hill , EngineeringPhysics , 2009,27.22-27.31

4.YQ. Jiang, Q. Zhou, and L. Lin , PLANAR MEMS

SUPERCAPACITOR USINGCARBON NANOTUBE

FORESTS, IEEE paper.5.T Helbling, S. Drittenbass, L. Durrer, C. Roman, C.

Hierold, ULTRA SMALL SINGLE WALLED CARBON

NANOTUBE PRESSURE SENSORS Micro and

Nanosystems, IEEE paper.


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THANK YOU!

carbon nanotube applications in engg

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