This document discusses various techniques for synthesizing nanomaterials, including top-down and bottom-up approaches. Top-down approaches like ball milling and mechanochemical activation use mechanical forces to break down larger particles into nanoparticles. Bottom-up approaches discussed include precipitation, hydrothermal, ultrasonication, microwave-assisted, and sputtering methods. For each technique, the document outlines the basic process, factors that affect the results, advantages, and limitations. The goal of nanomaterial synthesis is to produce particles with small, uniform size and identical composition, shape, and crystal structure while avoiding agglomeration.

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
‫العظيم‬ ‫هللا‬ ‫صدق‬

2. SYNTHESIS OF NANOMATERIALS
Mohamed Mohamed Esmat
Demonstrator
Faculty of postgraduate studies for advanced sciences
Materials science and nanotechnology department

7. Top -Down
Nanoparticles
Bottom-Up

8. Characteristics of Nano particles that
should posses by any fabrication
technique:
Getting a small size is not the only requirement.
It should have:
 Identical size of all particles
 Identical shape or morphology.
 Identical chemical composition and crystal structure
 Individually dispersed or mono dispersed i.e., no agglomeration.

9. Characteristics of Nano particles that
should posses by any fabrication
technique:

10. 1- Top down approach

11. Objectives of the milling process include;
1. particle size reduction
2.particle shape changes
Ball milling
The most effective ratio for the ball to powder masses
is 10 to 1.

13. Factors affect on ball milling process
• Milling Time
• Balls Number
• Balls weight
• Container volume
• Number of rounds per min.

14. Mechano-chemical activation
of copper ferrite
Time of milling, hrs.
-20 0 20 40 60 80 100 120
Crystallinesize,nm.
0
50
100
150
200
250
220 nm CuFe2O4 Ball milling
Time, hrs. 10 20 40 100
Size, nm 143 89 50 99
200 nm

16. 2. Bottom-up approach

17. Preparation from solids
Wt. = M * Mol. Wt. * V(L)
Preparation from liquids
M = (10 P * d ) / Mol. wt

18. • Used to prepare nanoparticles of metal
oxides.
• This process involves dissolving a salt
precursor usually a chloride, oxychloride, or
nitrate,
• Such as AlCl3 to make Al2O3

19. • Useful in preparing composites of different
oxides by co-precipitation of the corresponding
hydroxides in the same solution
Size and shape control?????

20. • The method is based on the ability of water and aqueous
solutions to dilute (at high temperature (500°C) and
pressure) substances practically insoluble under normal
conditions: some oxides, silicates, sulphides.
• They easily controlled the size of the NPs from 6 to 170 nm
by adjusting the experimental parameters such as
• The reaction duration,
• The initial pH ,and
• Initial concentration of the reactants.
Hydrothermal method

21. The main drawbacks
• The slow reaction kinetics.
• The high cost of equipment.
Advantages
• The ability to synthesis crystals of substances which are unstable
near the melting point.

22. • Application of powerful ultrasound radiation (20 KHz–10
MHz).
• Creation,
• Growth, and
• Collapse
What is the main drawback of this method????
Ultrasonication

23. Instrument

24. Microwaves are electromagnetic waves
Microwave

25. Instrument

26. • Microwaves will not affect the structure
of molecules.
• The effect of microwave is purely
kinetic.
• Fast

27. Conductive heating
Traditionally, chemical synthesis has been
achieved through conductive with external heat
source.
Slow (can take hours).
Insufficient for transferring energy into the system
because it depends on the thermal conductivity.
Uncontrolled.
Inhomogeneous temperature profiles within the
reaction flask.

28. Conventional heating

29. Microwave heating
Conversion of the electromagnetic
radiation into heat energy
• Heating is caused by:
1. Dipole rotation
 The interaction of the permanent dipole moment of
the molecule with the high frequency
electromagnetic radiation.
 Any polar species (solvent and/or substrate) that are
present will encounter this mechanism of energy
transfer.

30. Microwave heating
2. Ionic conduction:
 It results if there are free ions or
ionic species (dissolved (dissociated)
charged particles) present in the
substance being heated.

31. Microwave heating

32. Advantages
• Reaction rate acceleration
• Higher yields
• Easy handling
• Environmentally friendly
• Control morphology and size
• Save energy and time
• large-scale industrial production of high-quality advanced
nanomaterials
• Leads to a particle sizes in the range of 15–35 nm because of the
shorter synthesis time and highly focused local heating.

33. Factors
 Microwave heating is believed to be more dependent
on:
• The molecular properties
• The reaction conditions
• PH
• Temperature (power)
• Concentration
• Time

34. Sputtering

35. Instrument

36. Mohamed Esmat