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A
PRESENTATION ONCARBON NANOTUBES
By
Ashwini Shrirao
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Contents # Discovery
# Introduction# Properties# Synthesis
# Applications
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Discovery
Discovered by Sumio Iijima
Multi-walled Nanotube in 1991
Single-walled Nanotube in 1993
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Introduction
# Basic Structure
# Classification of Nanotube
1. Single-walled Nanotube2. Multi-walled Nanotube
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Basic Structure
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Types of
Nanotubes
1.Single Walled Nanotubesa. Zigzagb. Armchairc. Chiral
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Single Walled Nanotubes
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Single WalledNanotubes
How to Classify ?
Chiral Vector R =n
a1 +m
a2
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Single Walled Nanotubes
d = (n2 + m2 + nm)1/2 0.0783 nm
Chiral angle =tan-1( n/(2m + n))
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Ropes of Carbon Nanotubes
Lattice Parameter in CNT ropes = d + 0.34 nm
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ypes oNanotubes
2. Multi-walled Carbon Nanotubes
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Properties of CNT
1. Physical
2. Optical3. Electrical4. Thermal
5. Elastic
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Physical Properties
Average Diameter of SWNT 1.2-1.4 nmDistance from opposite carbon atoms (line 1) 2.83 A
Analogous Carbon atom separation (line 2) 2.456 A
Parallel carbon bond separation (line 3) 2.45 A
Carbon bond length (line4) 1.42 A
C C tight bonding overlap energy ~ 2.5 ev
Lattice constant 17 A
Density(10,10) Armchair(17,0) Zigzag
(12,6) Chiral
1.33 g/cm31.34 g/cm3
1.40 g/cm3
Interlayer Spacing(n,n) Armchair(n,0) Zigzag(2n,n) Chiral
3.38 3.413.39
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p ca roper es
Fundamental Gap:For (n, m); n-m is divisible by 3 [Metallic]
0 eVFor (n, m); n-m is not divisible by 3 [Semi-Conducting]
~ 0.5 eV
Egap =2y0acc /d
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Optical Properties
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Electrical Properties
Resistance6500
Maximum Current Density 1013
A/m2
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Thermal Properties
Thermal Conductivity ~2000
W /m-K
Phonon Mean Free Path ~ 100 nm
Relaxation Time ~ 10-11 s
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Elastic Properties
Young's Modulus (SWNT) ~ 1Tpa
Young's Modulus (MWNT) 1.28Tpa
Maximum Tensile Strength(MWCT)~63 GPa
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ElectronicProperties
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Synthesis Of carbon
Nanotubes
1. Arc Method
2. Laser Ablation
3. Chemical Vapour Deposition
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1. Arc Method
--Yield up to 30%by weight
--Further purificationis required
--Both SWNT and MWNT upto length
of 50um can be produced
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2. Laser Ablation
--Yield >70%by weight
--Produces primarilySWNT
--Further purification is required
--Most expensive method
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3. Chemical VapourDeposition
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Deposition
--Large volume of CNTs can beformed
--Plasma enhanced chemicaldeposition- synthesize vertically
aligned carbon nanotubes--Without the plasma, the resulting
nanotubes are often randomly
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Advantages
- Single-Walled Nanotubes
- Multi-Walled Nanotubes
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-Nanotubes
1. Their resistance to chemicals isimproved
2. Do not need a catalyst forgrowth
3. Do not contain magnetic
impurities
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Applications
# Field Emission# Molecular Electronics
# Fibres and Fabrics# Conductive Plastics# Catalyst Supports
# Biomedical Applications# Energy Storage