Carbon nano forms like fullerenes, and CNT's

1. CARBON NANOTUBES :A REVIEW ON
SYNTHASES, PROPERTIES AND
APPLICATIONS
PRESENTED BY:
M SAIBHARGAVA REDDY
17031D6609
Nano Technology

2. CONTENT
Introduction
 Synthesis of Nanotubes
Properties
Applications
Current Trends
Fee facts about Nanotechnology
References

3. Introduction :
Forms of Carbon
Carbon
Diamond(high temp &
pressure)
SP3 hybridization:cubis
Graphite(ambient
conditions)
SP2 hybridization:planar
Nanostructures (specific
growth conditons)
SWNTs MWNTs
Graphene
SP2 &2D Fullerene CNT
2D&cylindrical

4. SELECT THE CHEMICAL• In 1985 KROTO , CURL & SMALLEY from Rice university discovered C60 later they got NOBEL prize for
their contribution
• Fullerenes are 3D network of carbon atoms
• Containing pentagonal & hexagonal rings in which no two pentagons share an edge
• Each atom connected to exactly three nighbours and bonded by two single bonds & one double bond
• Followes EULER’S Polyhedron formula
• V – E + F = 2
• That there are exactly 12 pentagons in a fullerene &
𝑉
2
-10 hexagons
• Fullerenes with materials inside are called Cage compounds or Endohedral compounds ,eg:M@C60
• Materials outside are called Exohedral compounds ,both inorganic & organic groups added to the exterior
• Combination of Endo-and Exohedral compounds ,eg :Gd@C82(OH)n
Introduction about Fullerenes

5. CARBON
NANOTUBES
Long ,hollow cylindrical structure with the walls
formed by one atom thick sheets of carbon called
Graphene are rolled at specific & descrete angles .
Internal dia of 1 – 50 nm and length is 100nm upto
several micro meters longer
Combination of the rolling angle and radius decides
the nanotube proparties :metal or semiconductor
Individual nanotubes naturally align themselves in
“ropes” held together by vander walls forces
The chemical bonding of nanotubes is composed
entirely of SP2 bonds

6. HOW TO ROLL THE NANOTUBE
• A carbon nanotube is based on a two dimensional graphene sheet
• The chiral vector is defined on the hexagonal lattice
• Cℎ = 𝑛ȃ1 + 𝑛ȃ2
• Chiral vector: The vector pointing from the first atom towards the other & its
length is equal to the circumference of the nanotube
• The direction of nanotube axis is perpendicular to chiral vector

9. NAMING OF
NANOTUBES
The (n,m) nanotubes naming can be thought
as a vector (Ch) in an infinite graphene
sheet that describes how to “roll up” the
graphene sheet to make the nanotube . T
denotes the tube axis and a1 & a2 are the
unit vectors of graphene in real space
The integers n & m denote the number of
unit vectors along two directions in the
honeycomb crystal lattice of graphine

10. NAMING OF NANOTUBES
• If m=0 & θ=0˚ ,the nanotubes are called ZIG ZAG nanotubes
• If n=m & θ=30˚ ,the nanotubes are called ARMCHAIR nanotubes
• Otherwise ,they are called CHIRAL (0˚˂ θ˂30˚)
• Dia of an nanotube can be calculated from it’s (n,m) indices as followes
d =
𝑎
∏
𝑛2 + 𝑛𝑚 + 𝑚2
where a = 0.246 nm

11. SYNTHESIS OF CARBON NANOTUBES
• Arc discharge(1991 by Iijima)
• Laser ablation(1995 by Smalley)
• Chemical vapour deposition(1993)
• High pressure Carbon monoxide(HiPCo 1999)
• Cobalt-Nickel Catylist(CoMoCat 2000)

12. • ARC DISCHARGE :
• two graphite rods are placed in an enclosure that is filled with some inert gas (like helium or argon) at low pressure
(between 50 and 700 mbar).
• The carbon rods act as electrodes which are kept at different potentials.
• The anode is moved close to the cathode until an arc appears and the electrodes are kept at the distance of 1 mm for the
whole duration of the process that takes about one minute.
• After the de-pressurisation and cooling of the chamber the nanotubes together with the by-products, can be collected.
Most nanotubes deposit on the cathode.
• The synthesis product yield which represents the amount
of carbon nanotubes expected in the converted carbon is 60%

13. • LASER ABLATION :
• Intense laser pulses ablate a carbon target which is placed in a tube-furnace heated to 1200°C .
• During the process some inert gas like helium or argon flows through the chamber to carry the grown
nanotubes to the copper collector.
• After the cooling of the chamber the nanotubes and the by-products, like fullerenes and amorphous carbon
over-coating on the sidewalls of nanotubes can be collected.

14. Arc Discharge and Laser Ablation similarities :
• Condensation of C atoms generated from evoparation of solid carbon source.
• Both produce high quality SWNTs and MWNTs
• MWNTs :10’s of micro m long , 5-30 nm dia
• Produced in form of ropes consisting of several individual nanotubes close packed in hexagonal
crystels
• The use of pure carbon leads for both methods to the synthesis of multi-walled nanotubes
• The addition of a catalyst like iron, yttrium, sulphur, nickel and molybdenum leads to the formation of
the single-walled carbon nanotubes .
• As the temperatures involved in these methods are very high, e.g. up to 4000°C for the arc discharge ,
approximately 28% of the carbon anode evaporates

15. CHEMCAL VAPOUR DEPOSITION :
• During CVD, a substrate covered with metal catalysts, like nickel, cobalt, iron, or a
combination is heated to approximately 700°C .
• The growth starts after two gases are passed through the chamber, a carrier gas like
nitrogen, hydrogen or argon, and some hydrocarbon gas like acetylene (C2H2) or
methane (CH4).
• The synthesis production yield, which indicates the amount of carbon nanotubes in the
converted carbon, reaches 90% .
• CVD is commonly used for the industrial purposes because the method is already well
investigated and offers acceptable results on the industrial-scale.

16. MECHANICAL PROPARTIES
• The C-C bond in a graphene layer the strongest chemical bond in extended system
• Strongest and most flexible moleacular material (C-C covalent bonding and seamless hexagonal
network architecture).
• Maximum strain ᷉ 10 % :much higher than any other material
• Transport properties of conductive materials
Fiber material Specific density E (Tpa) Strength(Gpa)
CNT 1.3 - 2 1 10 - 60
HS Steel 7.8 0.2 4.1
Carbon Fiber 1.7 - 2 0.2 – 0.6 1.7- 5
Material Thermal conductivity(W/m.K) Electrial conductivity
CNT >3000 10ˆ6 - 10ˆ7
Diamond 1000 6*10ˆ7
Copper 400 2 – 8.5*10ˆ6
Carbon fiber 8-105 6.5 – 14*10ˆ6

17. APPLICATINS
• In Genetic Engineering:CNTs and CNHs are used to manipulate genes and atoms in the
development of bioimaging genomes, proteomics and tissue engineering.
• Biomedical applications :Detection of cancer at early stages is a critical step in improving cancer
treatment
• Artificial implants :due to their high tensile strength, carbon nanotubes filled with calcium and
arranged/grouped in the structure of bone can act as bone substitute.
• Preservative :. Their antioxidant property is used in anti aging cosmetics and with zinc oxide as
sunscreen dermatological to prevent oxidation of important skin components
• As catalyst :Nanohorns offer large surface area
• As Biosensors :. An example is the glucose sensing application, where regular self-tests of glucose by
diabetic patients are required to measure and control their sugar levels

18. CURRENT TRENDS
• Application of carbon nanotubes in drug delivery
• Carbon nanotube and polypyrrole composites :coating and dopping
• The role of metal – nanotube contact in the performance of CNT field – effect transistors
• Fully sealed , high – brightness carbon nanotube field emission display
• Carbon based materials as supercapasitor electrodes
• Maniaturized gas ionization sensors using CNTs

19. FEW FACTS ABOUT NANO TECHNOLOGY
• Brighter colors , Richer flavors , Less spoilage , those are some of the reasons why
companies are dumping nanoparticles into hundreds of products , including cosmetis.,
sunscreens, and food.
• Analysts say the global market for manufactured goods using nanomaterials could hit
$ 2 trillion by 2018.
• Studies show that nanoparticles can work their way into the bloodstream ,penetrate
cells, and get past the blood – brain barrier . Research has linked such particles to
lung damage: the brain may be affected too
• University of Southern California lab nanotubes have been used to create synthetic
neurons

20. REFERENCES :
• Nptel sources
• Synthesis of Carbon Nanotubes Polina Shifrina Polina Shifrina 12.05.2011
• H.W.Kroto, J.R.Heath, S.C.O' Brien, R.F.Curl, and R.E.Smalley, Nature, 318, (162, 1985
• Iijima, Sumio, Nature (London, United Kingdom), 354, (6348), 1991
• Google wekipedia

21. THANK
YOU …