1. CARBON NANO TUBES (CNTs)
Definition: When number of graphite sheets are rolled like a cylinder is called CNT.

2. Structure:
In CNT, all the carbon atoms are covalently bonded (tetrahedral).
But, the sheet lattices of graphite are held by Vanderwalls forces.

5. Two types of CNT:
Single walled (SWCNT)
If a nanotube has a
single cylinder of
graphite sheet, it is called
SWCNT.
diameter is 1-2 nm and
length is µm.

6. Types of SWCT
a) arm chair form b) Zigzag model c) Chiral model

8. Explanation
Zig-Zag = Rolling of graphene sheet in vertical direction w.r.t. tube axis Arm chair = Rolling of graphene sheet in horizotal direction direction w.r.t. tube axis Chiral = Rolling of graphene sheet in diagonal

10. Properties of CNT:
CNT possess only very few defects in the structure which is the main reason for their desirable and enhanced qualities.
1. Mechanical property:   
Flexibility is measured by Young’s modulus. CNT Young’s modulus is 5-10 times greater than that of steel.
Tensile strength of CNTs are times stronger than steel 

11. 2. Electrical property:
This depends on diameter, number of walls and chirality of the nanomaterial.

12. 3. Density CNT have density of 1.33 – 1.44 g.cm-3
while Al has 2.7g.cm-3.
It means that CNTs have density ½ to that of Al

13. 4. Thermal property: 10 times greater than steel.
5. Kinetic property: In MWCNT, during movement, there will be no friction between inner and outer walls. This is due to the graphite structure.

14. 6. Vibrational property:
a) A1g mode: This is symmetrical mode. The vibration is uniform throughout the inner plane and outer plane.
A1g

15. b). E2g mode: This is asymmetrical mode
b) E2g mode: This is asymmetrical mode. As the vibrations are competing in and out, they are lying between elliptical and spherical shape.
E2g

16. Differences b/w molecules, nanomaterials and bulk materials

17. Synthesis of nanomaterials Chemical Vapour Deposition (CVD)
Gas Phase Method Liquid Phase Methods Solid Phase Methods
Thermolysis
Chemical Precipitation
Hydrothermal synthesis
Solvothermal synthesis
Electrodeposition
Laser Ablation
Chemical Vapour Deposition (CVD)

18. SYNTHESIS OF NANO PARTICLES:
Bottom up method – Soft method – Chemical method – Small to big method:
This method involves building up of materials from the bottom, by atom by atom, molecule by molecule or cluster by cluster.
There are five important techniques under this method. No
Type
Example 1
Precipitation
BaSO4 Nano particles, Mo Nano partilces 2
Thermolysis
Li Nano clusters 3
Hydro thermal method
Iron oxide Nano particles 4
Solvo thermal method
ZnO, ZrO2 nano clusters 5
Vapour Liquid Solid (VSL) technique
Si nano wire

19. Eg Precipitation by Displacement reaction:
1) BaSO4 nano particle production
In presence of Sodium hexa meta phosphate (stabilizing agent),
Ba(NO3) Na2SO  BaSO NaNO3
Barium nitrate (Nano precipitate)

20. Eg 2) Precipitation by reduction reaction: Mo Nano particle production
MoCl Na B Et3 H  Mo (Nano) + 3 NaCl + 3 B Et H2
(Tri ethoxy boron hydride)
reducing agent

21. Thermolysis
At High temperature and in the presence of stabilising agents, metal precursors are decomposed to form nanomaterials. This is known as thermolysis.

22. Requirements vacuum chamber Precursor inert gas (Ar / He) Temperature
cold finger
scrapper

24. Lithium azide (LiN3) at 370oC, decomposes to N2 and Li.
2LiN3  2 Li + 3 N2

25. Hydrothermal synthesis [OR] Thermal Hydrolysis
Requirements: auto clave temperature – 400 oC pressure - 1 atm Advantages: Easy to control the size and shape. Disadvantages: Expensive autoclaves – safety problems – could not monitor the reaction.

26. elementary nano product is known as seed
The precursor is known as nutrient.

27. Example: nano Iron oxide production
2000C FeCl3 + 3 H2O  Fe (OH)3 + 3 HCl Fe(OH)3 + Ethanol + Ethylene oxide  α Fe2O3 (50 nm)

28. Vapour Liquid Solid Technique (VLS technique)

29. Example: Synthesis of silicon nano wire
Requirements
furnace
silicon substrate
Gold nanoparticles as catalyst
Silane ( SiH4 )

31. Solvothermal analysis
Requirements
non aqueous solution like Xylene, Ethylene diamine, Cyclo hexane, propanol
high temperature ( 100 – 1000 oC)
higher pressure. ( atm).

33. S.No
Content
Nano ZnO production
Nano ZrO2 production 1
Precursor
Zinc acetate di hydrate
Zirconium oxy chloride 2
Solvent
Propanol
Hexane 3
Stabilising agent
Sodium Hydroxide
Ammonium hydroxide 4
Capping agent
( to stop the growth)
Do decane thiol

34. Top down methods(or) Physical / hard / big to small methods
It involves conversion of larger particles to small nano scale particles. No
Method
Example 1
Laser Ablation
SWCNT 2
Chemical Vapour Deposition
CNT 3
Carbon arc method 4
Electrodeposition
Ni, Cu, Co Nano rods, nano wires, nano sheets

35. i) It is used to prepare SWCNT
Laser ablation method:
i) It is used to prepare SWCNT
ii) Components of Laser ablation set-up:
S.No
Component
Purpose 1
Furnace
To heat the set-up at 1200oC 2
Fused Silica Window
Through this, laser beam is sent 3
Graphite target
Contains the precursor 4
Laser source
Produces Nd-YAG ( Neodymium-Yttrium-Aluminium – Garnet) or CO2 laser bem 5
Inert gas inlet
To send Helium or Neon inert gas 6
Copper collector
At cooler end, it collects the nano particle

37. Example Acetylene 1100 oC CNT (Condensed over the catalyst)
Ni / Co / Fe + MgO

38. 3. Carbon arc method:
Two graphite electrodes of μm dia are taken, connected externally. At high pressure, when V AC current is passed, CNT is produced.

40. Cathode (-) Anode (+)
Cu2+

41. Porous Alumina Templates: To fabricate nanotubes

44. Thank You