NANOPARTICLES
USING
SOL GEL SCIENCE
Contracted nanoparticle aggregates which is
vibrating ( seen as a Blur) at one side of the cabon
film after disconnecting from the other side.
 Such systems can be translated from
solution into two demensional
representations on glass surfaces via
methods such as dip coating.
 In essense, the fractal nature can still be
seen but in a two demensional film
Sol- Gel Dipping Apparatus
Low density coating of SiO2 via
Sol-gel Dip Coating method
 The reaction going to completion first in
solution to form a sol is one way to do sol
gel dip coating
 Another way is to allow the reaction to be
incomplete or still proceed after dipping.
Sol-Gel Dip Coatings 1 to 10 Layers
One Layer
Two Layers
AL doped
ZnO layers
Five Layers
Ten layers
Demostration Experiments
 Sol-Gel Synthesis via TMOS
 Sol-Gel Synthysis using Sodium silicate
better known as furnace cement.
 Ultrasonic synthesis of TMOS
SOL-GEL SCIENCE
Mix the reactives
 Gelification
Hydrolysis and Condesation
reactions take place
 Aging
 Soaking
Sol
Gelification
Gel
Aging
Drying
Gel
Aerogel
Gelification
OR
+
Si
OR
Mix reactives
OR
OR
H2O
OR
OR
OR
OR
Hydrolysis and Condesation
reactions take place
OR
+
Si
OR
OR
HO
OR
Si
OR
Gel
OH
+
HO
OR
OR
Aging
Gel
O
Si
OR
OR
Sol
Gelification
OR
OR
Si
OR
OR
OR
+
ROH
+
H2O
OR
Si
OR
OR
OR
OR
Si
ROH
OR
OR
Si
OR
+
Si
HO
O
Si
OR
OR
Designing Nanomaterials
First Step
Silica Solution
Precursor: Tetraetilortosilicate
Si(OCH2CH3)4
Solvent: Ethanol
Catalyst: OxalicAcid
Modifications
pH (final product)
Temperature (crystal phase)
Precursor (Type of material)
Time (Strength)
etc
Time vs pH
280
260



V
240
D
E
S
I
G
N
I
N
G
Gelification Time, min
220
200
180
160
140
120
100
80
60
40
Gel
Shrinkage
20
No gel
formation
Precipitation
0
6
7
8
9
pH
10
11
12
Aging
Once there is a gel, chemical reactions still keep
taking place. These further reactions add strength to
the solid network.
Gel
Stronger Gel
Aging
Aerogeles y Xerogeles
Special Drying
Tecniques
Aerogel
Gel
Evaporation
Xerogel
Synthesis of Titania
 Up to now
many methods have been
established for the synthesis of titania. The
sol-gel technique being the most important
 Unfortunately, the sol-gel technique derived
precipitates are amorphous in nature which
requires further treatment to form
crystalline phase.
Sol Gel Preparation of Anatase
TiO2 NanoParticles
 When done under controlled conditions size
of particle can be reduced to < 10 nm
 Controlling Hydrolysis and concentration is
a must.
 Important in our work for constructing
highly active nanocrystalline photocatalysts.
Ti(OET)4 + H2O(excess)
Acid
Precipitate
No
Yes
No
Heat
Heat
Yes
Yes
No
Anatase < 70%
Rutile >30
Anatase +
Trace Brookite
Anatase +
Trace Brookite
Anatase =70%
Bookite =30
Forms gel
Forms gel
no gel
no gel
Selective synthesis with
Ultrasound.
IRON OXIDE
Average diameter = 8 nm
Particles
Stabilized
with Oleic