NANDHINI

1. Prepared by,
B.NANDHINI
K.KOWSALYA
M.VAITHEESWARI
B.VIJAYALAKSHMI

2.  Allotropes of carbon with a cylindrical
structure
 Can be capped on the ends with buckyballs or
open ended
 Composed entirely of sp2 bonds

3. NANOTUBE
CNT

4.  #1952
 Radushkevich and Lukyanovich publish a paper in the Soviet Journal of Physical
Chemistry showing hollow graphitic carbon fibers that are 50 nanometers in
diameter.
 #1979
 John Abrahamson presented evidence of carbon nanotubes at the 14th Biennial
Conference of Carbon at Pennsylvania State University.
 #1981
 A group of Soviet scientists published the results of chemical and structural
characterization of carbon nanoparticles produced by a thermocatalytical
disproportionation of carbon monoxide.
 #1991
 Nanotubes discovered in the soot of arc discharge at NEC, by Japanese researcher
Sumio Iijima.

5.  Classified mainly in two types:
 1. SINGLE WALLED NANOTUBES
 2. MULTI WALLED NANOTUBES

6.  Diameter :- 1 nanometer
 Band gap :- 0-2ev
 A one atom thick layer of graphene into seamless
cylinder .
 Their electrical conductivity can show metallic or
semiconducting behaviour.

7.  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.  STRENGTH
 HARDNESS
 ELECTRICAL PROPERTIES
 THERMAL CONDUCTIVITY
 EM WAVE ABSORPTION
 THERMAL PROPERTIES

9.  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.

10. Arc Discharge
Laser Ablation
Chemical Vapor
Deposition (CVD)

11.  Carbon is in the gas phase
 Energy source transfers energy to carbon
molecule
 Common Carbon Gases
◦ Methane
◦ Carbon monoxide
◦ Acetylene (C2H2)

12.  Carbon is in the gas phase
 Energy source transfers energy to carbon
molecule
 Usually a silicon plate coated with iron
particles is the substrate.
 Common Carbon Gases
◦ Methane
◦ Carbon monoxide
◦ Acetylene

13.  After energy transfer, the carbon molecule binds
to the substrate
 Temperature between ~1300⁰F
 Carbon nanotubes stick to each other due to
Vander walls force.
 When tubes are extracted , cling on to each other
and pull each other out of substrate
 Yield is usually about 30%
 One of the most common methods of carbon
nanotube synthesis

14. MERITS:
Easy to increase scale to industrial
production
Large length
Simple to perform
Pure product
DEMERITS:
 Defects are common.