際際滷

際際滷Share a Scribd company logo
SOL-GEL TECHNIQUE
A SOL IS A DISPERSION OF THE SOLID PARTICLES
(~ 0.1-1 M) IN A LIQUID
A GEL IS A STATE WHERE BOTH LIQUID AND SOLID ARE
DISPERSED IN EACH OTHER, WHICH
PRESENTS A SOLID NETWORK CONTAINING LIQUID
COMPONENTS. THE SOL-GEL COATING PROCESS
USUALLY CONSISTS OF 4
STEPS:
(1) THE DESIRED COLLOIDAL PARTICLES ONCE DISPERSED IN A LIQUID TO FORM
A SOL.

(2) THE DEPOSITION OF SOL SOLUTION PRODUCES THE COATINGS ON THE
SUBSTRATES BY SPRAYING, DIPPING OR
SPINNING.
(3) THE PARTICLES IN SOL ARE POLYMERIZED THROUGH THE REMOVAL OF THE
STABILIZING COMPONENTS AND PRODUCE A
GEL IN A STATE OF A CONTINUOUS NETWORK.
(4) THE FINAL HEAT TREATMENTS PYROLYZE THE REMAINING ORGANIC OR
INORGANIC COMPONENTS AND FORM AN
AMORPHOUS OR CRYSTALLINE COATING[1-4]
COLLOIDS=MICROSCOPIC
MATERIALS+DISPERSION PHASE
 A COLLOID IS A SUBSTANCE MICROSCOPICALLY DISPERSED THROUGHOUT
ANOTHER SUBSTANCE.
 THE DISPERSED-PHASE PARTICLES HAVE A DIAMETER OF BETWEEN
APPROXIMATELY 1 AND 1000 NANOMETERS.[2] SUCH PARTICLES ARE
NORMALLY INVISIBLE IN AN OPTICAL MICROSCOPE, THOUGH THEIR PRESENCE
CAN BE CONFIRMED WITH THE USE OF AN ULTRA MICROSCOPE OR AN
ELECTRON MICROSCOPE.
LIGHT BEING SHINED THROUGH WATER AND MILK. THE
LIGHT IS NOT REFLECTED WHEN PASSING THROUGH THE
WATER BECAUSE IT IS NOT A COLLOID. IT IS HOWEVER
REFLECTED IN ALL DIRECTIONS WHEN IT PASSES THROUGH
THE MILK, WHICH IS COLLOIDAL.
PRECURSOR
ORGANOMETALLIC
COMPOUND
(M-OR)
Sol gel chemistry
ORGANOMETALLIC COMPOUND(M-OR) +WATER
(H20)
METAL-OXIDE SOLUTION

So
l

COATING

GELLING
PRECIPITATING

M-OH +R-OH
XEROGEL

WET GEL
UNIFORM PARTICLES
Sol gel chemistry
Sol gel chemistry
SOL-GEL FOR NORMAL COATING
SOL GEL FOR SPIN COATING
ADVANTAGES OF SOL-GEL METHOD

( SIMPLE ,
EFFECTIVE

ECONOMIC &
)

HIGHLY PURE PRODUCTS
UNIFORM NANOSTRUCTURE
&EASILY SHAPEABLE
HAVE LOW TEMP. SINTERING
CAPABILITY
DISADVANTAGES OF SOL-GEL
TECHNIQUE

SUBSTRATE
dependent
NON_UNIFORM
THERMAL
EXPANSION
APPLICATIONS
CAPACITORS IN
PIEZOELECTRICITY
APP.

TRANSPARENT
SEMICONDUCTOR
S

GLASSES
,LENSES

NANOPOWDER
FOR DENTAL
&BIOMEDICAL
APP.
Sol gel chemistry

More Related Content

Sol gel chemistry