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Sol-Gel

Sol-Gel. Why Sol-Gel..?. -. What’s Sol-Gel.. . 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. Sol-Gel.

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Sol-Gel

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  1. Sol-Gel

  2. Why Sol-Gel..? -

  3. What’s Sol-Gel.. • 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

  4. 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

  5. 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

  6. Sol-Gel synthesis: …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.

  7. Condensation: 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

  8. Sol-Gel for TEOS TEOS AND WATER TEOS polymerization

  9. Sol-Gel technologies…

  10. Factors affecting Sol-Gel • Variation of gelation time with PH

  11. As the temperature increases the gelation time decreases.

  12. Applications… • 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 • BaTiO3electronic material for capacitors

  13. Advantages: • 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

  14. Thank You By Sai Charan

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