sol-gel. - why sol-gel..? applicationsconventional methods glass preparation and ceramics high...
DESCRIPTION
Process in which solid nano particles are dispersed in a liquid (a sol) and agglomerate together to form a continuous three-dimensional network extending throughout the liquid (a gel) Involves hydrolysis and poly-condensation What’s Sol-Gel..TRANSCRIPT
Sol-Gel
-
Why Sol-Gel..?
Applications Conventional methods
Glass preparation and ceramics
High temparature, thermal decomposition, limited materials
DSSC(thin TiO2 films)
Cumbersome, non-uniform and high temp.
Coatings and thin film applications
Accessibility limitations, scaling, costly and energy intensives
Process in which solid nano particles are
dispersed in a liquid (a sol) and agglomerate together to form a continuous three-dimensional network extending throughout the liquid (a gel)
Involves hydrolysis and poly-condensation
What’s Sol-Gel..
Solid particles (up to few 100 nm) suspended
in liquid phase i.e. Sol
Solid macromolecule (polymer chains) immersed in liquid phase i.e. Gel
Particles in Sol condense in new phase Gel
Sol-Gel..
Precursors: Metal alkoxides and metal chlorides(as they
readily react with water) e.g. TEOS
Colloid contain broad range of solid(or liquid) particles dispersed in various degrees in liquid.
Sedimentation and centrifugation
Drying and firing
…consists of hydrolysis and condensation. Hydrolysis: M(OR)x + H2O → HO-M(OR)x-1 + R-OH R: -CH3, -C2H5 etc. M:Si, Al, Ti etc.
Sol-Gel synthesis:
1. Alcohol condensation:(OR)x-1-MOH + ROM-(OR)x-1 → (RO)x-1-MOM-(OR)x-1 + ROH
2. Water condensation:(OR)x-1-MOH + HOM-(OR)x-1 → (RO)x-1-MOM-(OR)x-1 + HOH
Condensation:
Sol-Gel for TEOS
TEOS AND WATER
TEOS polymerization
Sol-Gel technologies…
Variation of gelation time with PH
Factors affecting Sol-Gel
As the temperature increases the gelation time decreases.
Synthesis of ceramics, glass, fibres Thin films on substrate Nuclear fuels (UO2 and ThO2 ) Aerogels and xerogels Optical and refractory ceramic fibers Zeolite synthesis Powder abrasives Optical coating, protective coating on
plastic, glass, metals BaTiO3 electronic material for capacitors
Applications…
Cheap and low temp. operation Very thin films of metal oxides can be
obtained Uniform distribution of components and
porosity Better alternative approach to conventional
production of glasses Easy dopant addition in ceramics processing Sol gel material can be obtained as bulks, thin
films, (nano) powders
Advantages:
Thank You
By Sai Charan