Gaxela N, Manaetja K.P, Mulaudzi S, Senosi R
Supervisor: Dr V.L.Katkof
TABLE OF CONTENTS
 Introduction
 Classification of CNTs
 Applications
 Properties
 Conclusions
INTRODUCTION
• Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure.
• Their properties are valuable for nano-technology, electronics, optics and other
fields of materials science and technology.
•
They also possess thermal conductivity, mechanical and electrical properties.
 Their name is derived from their long, hollow structure with the walls formed by oneatom-thick sheets of carbon, called graphene.
 These sheets are rolled at specific and discrete angles.
 Multi-walled nanotubes (MWNT) consist of multiple rolled layers (concentric tubes)
of graphite.
 In this work, we have investigated the bandstructures and the effective mass of
nanotubes.
• The calculations were performed using the tight-binding approach and roman lab
programme was used to draw the energy bandstructures of carbon nanotubes.
STRUCTURES
A CNT is characterized by its Chiral Vector:
Ch = n â1 + m â2,   Chiral Angle with respect to the zigzag
axis A Single-Walled Carbon Nanotubes structure is
expressed in terms of one-dimensional unit cell.
a
b
c
a) Armchair (n=m) f.e. (5,5)
 = 30
b) Zig Zag (n=0,m≠0) f.e (9,0)
 = 0
c) Chiral (n≠0,m≠0) f.e (10,5)
0 < < 30
Multi-walled carbon nanotubes
Classification of Carbon
nanostructures
 There are several parameters that characterizes the
nanostructures which include but not limited:
 Hybridization –
Sp : - Carbine
Sp2 : - Graphene
Sp3: -Graphite
 Dimensions (Lengths, Width and Thickness)
APPLICATIONS
1.
Structural- properties, many structures have been proposed ranging from everyday items like clothes and sports
gear to combat jackets and space elevators
2.
Electrical circuits- Large structures of carbon nanotubes can be used for thermal management of electronic
circuits.
3.
Electric cables and wires- Wires for carrying electrical current may be fabricated from pure nanotubes and
nanotube-polymer composites.
4.
Paper batteries (a battery engineered to use a paper-thin sheet of cellulose) - The nanotubes act as electrodes;
allowing the storage devices to conduct electricity.
5.
Solar cells- developed at the New Jersey Institute of Technology use a carbon nanotube complex, formed by a
mixture of carbon nanotubes and carbon buckyballs (known as fullerenes) to form snake-like structures
6.
Ultracapacitors- MIT Laboratory for Electromagnetic and Electronic Systems uses nanotubes to improve
ultracapacitors
7.
Medical- In the Kanzius cancer therapy, single-walled carbon nanotubes are inserted around cancerous cells, then
excited with radio waves, which causes them to heat up and kill the surrounding cells.
PROPERTIES
p = 0, ±1, ±2 …
a) Metallic nanotubes
b) Semiconductor nanotubes
ENERGY BANDSTRUCTURE OF
GRAPHENE MONOLAYER
E
Px
E-Ef ~ |P|
Py
ENERGY BANDSTRUCTURE OF
E BILAYER
GRAPHENE
E
E-Ef ~ P2
Py
Px
ENERGY BANDSTRUCTURE OF
FEW-LAYER GRAPHENE

CALCULATION OF EFFECTIVE
MASS FOR NANOTUBES
DEFINITION:
RESULTS:
CONCLUSIONS
The set of effective mass for carbon nanotubes was
calculated. Tight binding approach was used. It was
shown that for the (5, 5) nanotube eff. Mass for first
branch equal to 0, for other branches it has the order of
the magnitude of silicon effective mass
ACKNOWLEDGEMENTS
THANK YOU
Спасиьо SPA-SÉE-BA
RE A LEBOGA
RI A LIVHUWA