NANOPARTICLES USING SOL GEL SCIENCE Contracted nanoparticle aggregates

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 Si. O 2 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 Zn. O 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 Mix reactives Hydrolysis and Condesation reactions take place Sol Gelification Gel Aging Gel

Designing Nanomaterials First Step Silica Solution Precursor: Tetraetilortosilicate Si(OCH 2 CH 3)4 Solvent: Ethanol Catalyst: Oxalic. Acid Modifications p. H (final product) Temperature (crystal phase) Precursor (Type of material) Time (Strength) etc

Time vs p. H D E S I G N I N G Shrinkage Gel Precipitation V No gel formation

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 Ti. O 2 Nano. Particles ¨ 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 + H 2 O(excess) Acid Precipitate No Yes No Heat Yes No Anatase < 70% Rutile >30 Anatase + Trace Brookite Anatase =70% Bookite =30 Forms gel no gel

Selective synthesis with Ultrasound. IRON OXIDE Average diameter = 8 nm Particles Stabilized with Oleic