STM image of a single-walled
carbon nanotube
AFM image of SWNTs and SWNT bundles
Methods for Preparation of SWNTs
Arc-Charge
Laser Ablation
Chemical Vapor Deposition
1200C Furnace
Nd,YAG Laser
500 torr Ar
C target (2% Ni:Co)
Cold finger as collector
Laser Ablation
1200C Furnace
catalyst
Feed gas
FeedStock Gas,CO,CH
4
,etc.
Catalyst,Fe,Mo,Ni,Co etc.
Temperature,700 – 1100 oC
Chemical Vapor Deposition
Laser Method
CVD Method
Arc Method
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Carbon getting Saturated
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Carbon getting Saturated
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Carbon getting Saturated
Top-growth
Schematic show of the growth mechanism of SWNT by CVD
Deposition of carbon
Carbon getting Saturated
Base-growth
Top-growth
Schematic show of the growth mechanism of SWNT by CVD
普通化学第2-4 章
Substrate
CH
4
Purification of SWNT
SWNT
Small carbon pieces
soluble in basic H
2
O
Catalytic particles
Reflux in HNO
3
Raw Materials,
SWNT
Amorphous carbon
Catalytic particles
Cross Flow
Filtration
SWNT
Catalytic particles
Strong magnet
SWNT
(Jie Liu et al.,Science,280,1253-1256)
Acid Based Purification
Before Purification After Purification
Cutting SWNTs,
Why we need to do it and what is the challenge
As-purified SWNTs are tangled,nearly endless
ropes.
Some applications prefer short nanotubes:
Using SWNT as quantum wires in molecular
electronic devices
Challenge,The end of nanotubes are much more
reactive than the side wall !!
AFM Images of Cut SWNT
Shortening of Cut SWNT
Length (nm)
0 200 400 600 800 1000 1200 1400
Distribution (a.u.)
0
1
2
3
4
5
6
SN cut (no polishing)
266 nm
Length (nm)
0 200 400 600 800 1000 1200 1400
Di
stri
bu
ti
on (
a
.u
.)
0
2
4
6
8
10
12
14
In hot SN for one hour
147 nm
Solution Properties of SWNTs
Water with Surfactant;
– nanotubes are in bundles
DMF and Similar Solvent;
– Form very good
suspension/solution with
purified SWNT;
– Nanotubes in solution are
all individual.
Properties of Single Walled Carbon Nanotubes
Size
Density
Tensile Strength
Resilience
Current Carrying
Capacity
Field Emission
Heat Transmission
E-beam lithography can create lines
50 nm in wide,a few nm thick
SWNT
0.6 to 0.8 nm in diameter
By comparison
1.33 to 1.40 g/cm
3
45 billion pascals
Can be bent at large angels and
restraightened without damage
Estimated at 1 billion amps
per square centimeter
Can activate phosphors at 1-3 V if
electrodes are spaced 1μm apart
Predicted to be as high as 6,000
W/m?K
Stable up to 2,800oC in vacume,
750 oC in air
$1,500/g from Bucky USA
Al,2.7 g/cm
3
High-strength steel alloys break
at 2 billion Pa
Metals and carbon fibres fracture
at grain boundaries
Copper wires burn out at about
1 milion A/cm
2
Mo tips require fields of 50-100
V/pm and have limited lifetimes
Nearly pure diamond transmits
3,320 W/m?K
Metal wires in microchips melt at
600 to 1,000 oC
Au,about $10/g
Temperature
Stability
Cost