Carbon nanotubes are cylindrical nanostructures made entirely of carbon atoms. They have a length-to-diameter ratio of up to 132,000,000:1. There are two main types: single-walled nanotubes consisting of a single graphene cylinder, and multi-walled nanotubes containing multiple graphene cylinders. Carbon nanotubes were first discovered in the 1970s and were fully characterized in the early 1990s. They exhibit extraordinary strength and electrical conductivity and have a wide variety of potential applications, including in materials science, electronics, optics, and biomedical engineering.

1. Carbon Nanotubes
- a breakthrough in science
nano
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CARBON

2. What are carbon nanotubes?
 Carbon nanotubes (CNTs) are allotropes of carbon
with a cylindrical nanostructure.
 Nanotubes have been constructed with
length-to-diameter ratio of up to 132,000,000:1 .
 They have unusual properties, which are valuable
for nanotechnology, electronics, optics and other fields of
materials science and technology.
 Nanotubes are members of the fullerene structural family.
 The chemical bonding of nanotubes is composed entirely
of sp2 bonds, similar to those of graphite.

3. History of the Nanotubes
 The history of carbon nanotubes is not entirely clear, giving proper credit to the person that invented the carbon
nanotube has been the subject of several high tech debates among the scientific communities.
 The initial history of nanotubes started in the 1970s. A preparation of the planned carbon filaments was
completed by Morinobu Endo who was earning his Ph.D. at the University of Orleans, France.
 In 1991 the true first invention of nanotube was finally made. In 1993 Iijima and Donald Bethune found single
walled nanotubes known as buckytubes. This helped the scientific community make more sense out of not only
the potential for nanotube research, but the use and existence of fullerenes.
 With this information, the complete discovery of carbon nanotubes was realized and Iijima and Bethune were
ultimately credited with their discovery in their entirety.
 Roger Bacon is technically the first scientist to discover these hollow tubes of carbon that are
changing lives on a daily basis.
 Since the initial rediscovery of the nanotubes in 1991, who discovered carbon nanotubes is no longer as
important as who can come up with the most practical applications.

4. Types of carbon Nanotubes
 Classified mainly in two types:
1. SINGLE WALLED NANOTUBES
2. MULTI WALLED NANOTUBES
 OTHER RELATED STRUCTURES:
i. TORUS
ii. NANOBUD
iii. GRAPHENATED CARBON NANOTUBES (g-CNTS)
iv. NITROGEN DOPED CARBON NANOTUBES (N-CNTS)
v. PEAPOD
vi. CUP-STACKED CARBON NANOTUBE

5. SINGLE WALLED NANOTUBES
 Diameter :- 1 nanometer
 Band gap :- 0-2ev.
 SWNTs with diameters of an order of a nanometer can be excellent conductors.
 Their electrical conductivity can show metallic or semiconducting behaviour.
 Single-walled nanotubes are dropping precipitously in price, from around $1500 per
gram as of 2000 to retail prices of around $50 per gram of as-produced 40–60% by
weight SWNTs as of March 2010.
 SWNTs have been viewed as too expensive for widespread application but are forecast to
make a large impact in electronics applications by 2020 according to The Global Market
for Carbon Nanotubes report.

6. Single Walled Carbon Nanotubes

7. MULTI WALLED NANOTUBES
Multi-walled nanotubes (MWNT) consist of multiple rolled layers (concentric
tubes) of graphene.
Interlayer distance :- 3.4 Å
To describe structure of MWNT there are two models:-
1. Russian doll model
2. Parchment model

8. MULTI WALLED NANOTUBES

9. OTHER RELATED STRUCTURES
 TORUS:-
 It is a carbon nanotube bent in a torus shape (i.e. doughnut shape)
 NANOBUD :-
 Carbon Nanobuds are created combining carbon nanotubes and fullerenes
 GRAPHENATED CARBON NANOTUBE :-
 They are new hybrids that combines graphitic foliates grown along the sidewalls of MWNT.
 NITROGEN DOPED CARBON NANOTUBE :-
 These are used for enhancing storage capacity of Li-ion batteries.
 N-doping provides defects in the walls of CNT's allowing for Li ions to diffuse into inter-wall space
 PEAPOD :-
 A carbon peapod is a novel hybrid carbon material which traps fullerene inside a Carbon nanotube.
 CUP-STACKED CARBON NANOTUBES :-
 CSCNTs exhibit semiconducting behaviours due to the stacking microstructure of graphene layers.

10. OTHER RELATED STRUCTURES
TORUS
NANOBUD
GRAPHENATED CNT
NITROGEN DOPED CNT
PEAPOD
CUP STACKED CNT

11. PROPERTIES
STRENGTH :-
 Carbon nanotubes are the strongest, flexible and stiffest materials yet discovered in terms of tensile strength and elastic
modulus respectively.
HARDNESS :-
 The hardness (152 Gpa) and bulk modulus (462–546 Gpa) of carbon nanotubes are greater than diamond, which is
considered the hardest material.
ELECTRICAL PROPERTIES:-
 Because of the symmetry and unique electronic structure of graphene, nanotube has a very high current carrying capacity
THERMAL CONDUCTIVITY:-
 All nanotubes are expected to be very good thermal conductors along the tube, but good insulators
laterally to the tube axis.

12. PROPERTIES (Cont….)
 EM WAVE ABSORPTION:-
 There has been some research on filling MWNTs with metals, such as Fe, Ni, Co, etc., to increase the absorption
effectiveness of MWNTs in the microwave regime.
 THERMAL PROPERTIES:-
 All nanotubes are expected to be very good thermal conductors along the tube, but good insulators laterally to the
tube axis.
 TOXICITY:-
 Under some conditions, nanotubes can cross membrane barriers, which suggests that if raw materials reach the
organs they can induce harmful effects such as inflammatory and fibrotic reactions.
 CRYSTALLOGRAPHIC DEFECT:-
 As with any material, the existence of a crystallographic defect affects the material properties. Defects can occur in
the form of atomic vacancies.

13. Mechanical Properties of Engineering Fibers
Fiber material Specific
Density
Young's
modulus(Tpa)
Strength
(Gpa)
Strain at
break(%)
Carbon Nanotube 1.3 – 2 1 10 – 60 10
HS Steel 7.8 0.2 4.1 <10
Carbon fiber-PAN 1.7 – 2 0.2 – 0.6 1.7 – 5 0.3 – 2.4
Carbon fiber-Pitch 2 – 2.2 0.4 – 0.96 2.2 – 3.3 0.27 – 0.6
E/s-Glass 2.5 0.07 – 0.08 2.4 – 4.5 4.8
Kevlar-49 1.4 0.13 3.6 – 4.1 2.8
Properties of Conductive Materials
Material Thermal conductivity Electrical conductivity
Carbon Nanotube > 3000 10^6 – 10^7
Copper 400 6 x 10^7
Carbon fiber-Pitch 1000 2 - 8.5 x 10^6
Carbon fiber-PAN 8 - 105 6.5 - 14 x 10^6

14. SYNTHESIS
There are three methods for the synthesis of carbon nanotubes
:-
 ARC DISCHARGE
 LASER ABLATION
 CHEMICAL VAPOUR DEPOSITION

15. ARC DISCHARGE
METHOD ACTUAL APPARTUS

16. LASER ABLATION
METHOD ACTUAL APPARTUS

17. CHEMICAL VAPOUR DEPOSITION
METHOD ACTUAL APPARTUS

18. APPLICATIONS
 Biomedical
Researchers from Rice University and State University of New York have shown that the addition of low weight % of
carbon nanotubes can lead to significant improvements in the mechanical properties of biodegradable polymeric nano
composites for applications in tissue engineering including bone, cartilage, muscle and nerve tissue.
 Structural
 Electrical circuits
Because of the carbon nanotube's superior mechanical properties, many structures have been proposed ranging
from everyday items like clothes and sports gear to combat jackets and space elevators. However, the space elevator
will require further efforts in refining carbon nanotube technology, as the practical tensile strength of carbon
nanotubes must be greatly improved
Nanotube-based transistors, also known as carbon nanotube field-effect transistors (CNTFETs), have been made that
operate at room temperature and that are capable of digital switching using a single electron . However, one major
obstacle to realization of nanotubes has been the lack of technology for mass production

19. APPLICATIONS (Cont….)
 Electrical cables and wires
Wires for carrying electric current may be fabricated from pure nanotubes and nanotube-polymer composites. It has already been
demonstrated that carbon nanotube wires can successfully be used for power or data transmission.
 Solar cells
One of the promising applications of single-walled carbon nanotubes (SWNTs) is their use in solar panels, due to their strong UV/Vis-NIR
absorption characteristics. Research has shown that they can provide a sizable increase in efficiency, even at their current unoptimized state
 Radar absorption
Radars work in the microwave frequency range, which can be absorbed by MWNTs. Applying the MWNTs to the aircraft would cause the
radar to be absorbed and therefore seem to have a smaller radar cross-section. One such application could be to paint the nanotubes onto
the plane
 Supercapacitor
MIT Research Laboratory of Electronics uses nanotubes to improve supercapacitors. The activated charcoal used in conventional
ultracapacitors has many small hollow spaces of various size, which create together a large surface to store electric charge.

20. APPLICATIONS (Cont….)
 Optical power detectors
A spray-on mixture of carbon nanotubes and ceramic demonstrates unprecedented ability to resist damage while absorbing laser light. Such
coatings that absorb as the energy of high-powered lasers without breaking down are essential for optical power detectors that measure the
output of such lasers.
 Acoustics
One of the promising applications of single-walled carbon nanotubes (SWNTs) is their use in solar panels, due to their strong UV/Vis-NIR
absorption characteristics. Research has shown that they can provide a sizable increase in efficiency, even at their current unoptimized state
 Environmental remediation
A CNT nano-structured sponge (nanosponge) containing sulfur and iron is more effective at soaking up water contaminants such as oil,
fertilizers, pesticides and pharmaceuticals. Their magnetic properties make them easier to retrieve once the clean-up job is done.
 Water treatment
It has been shown that carbon nanotubes exhibit strong adsorption affinities to a wide range of aromatic and aliphatic contaminants in
water,due to their large and hydrophobic surface areas. They also showed similar adsorption capacities as activated carbons in the presence
of natural organic matter. As a result, they have been suggested as promising adsorbents for removal of contaminant in water and
wastewater treatment systems.

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