3. SOL
GEL
It is a colloidal form
( the dispersed particles are so small that
gravitational forces do not exist; particles show weak
van-der Waal’s forces)
Or
Molecular suspension of solids particles in a solvent.
It is a semi-rigid mass that forms when solvent from
the sol begins to evaporate and the particles or ions
left behind begin to join together to form a continuous
network.
4. Sol-gel Method
• This method has been using since many decades.
• Versatility of this method was re-introduced when glass was prepared
in 1970 using this method without high temperature
• A wet-chemical technique that uses either a chemical solution or
colloidal particles (sol–nanoscale particles) to produce an integrated
network (gel).
5. Sol-gel Method
• Formation of metal oxides involves connecting the metal centers with
oxo of hydroxo bridges therefore generating metal-oxo or metal
hydroxo polymers in solutions.
• After the drying process, the liquid phase is removed from the gel.
This may be followed by other heat treatment steps e.g. calcination.
Si-OR + H-OH Si-OH + ROH
Si-OH + HO-Si Si-O-Si + H20
Si-OR +HO-Si Si-O-Si+ ROH
13. Synthesis of nanomaterials of 𝑩𝒊𝟏−𝒙𝑳𝒂𝒙𝑭𝒆𝑶𝟑
( x= 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0)
• Requirements
Metal Nitrate :
❖ Bi Nitrate
❖ Iron Nitrate
❖ La Nitrate
Fuel Agents :
❖ Urea
❖ Glycine
Glassware : ( Beakers )
Apparatus : (Digital Balance, PH meter, Hot plate/Magnetic stirrer )
14.
15. Sol-gel synthesis
Advantages
• Simple, low cost, and provides
high yield
• Synthesize at low temperature
• Control of chemical composition
• High-scale homogeneity and
purity
• Produce high quality materials
Disadvantages
• Time taking process
• High cost raw materials
• Environmental concerns
