TKMM COLLEGE NANGIARKULANGARA

SOL-GEL SYNTHESIS

COLLOIDAL PRECIPITATION

CO-PRECIPITATION

COMBUSTION TECHNIQUE

HYDROTHERMAL TECHNIQUE

HIGH ENERGY BALL MILLING

SONOCHEMISTRY

Wet chemical technique Chemical solution deposition

For gel like properties particle density shoud be increased by removing significant amount of solvent

SOL GEL

Sedimentation

Centrifugation

Drying process (shrinkage and densification)

Thermal treatment/firing process (favourpolycondensation , enhance mechanical properties and structural stability via final sintering,densification and grain growth)

Densification can be achieved at a much lower temperature

Sol-gel approach is a cheap and low temperature technique that allows for the fine control of products’ chemical composition

Synthesis of nano particles of gold,silver

Tetrachloroauric acid

trisodium citrate(reductant)

Gold particles (purple colour)

HAu+3Cl4 Au0

Frens-Turkevich method

Simple and low cost process

Applicable to preparation of magnetic nanoparticles

Iron oxide nano particles are synthesised by co-precipitation reaction of FeCl3 and 1,2,4,5-benzene tetracarboxylic acid

FeCl3, NaOH and 1,2,4,5-benzene tetracarboxylicacid are dissolved in water and shaked for 10 minutes

Filtered and dried in air

Obtained powder is calcined at 4500C for 2 hours

Iron oxide nanoparticles are obtained

Morphology of Fe3O4 powder consists of cubic phase with size of 24 nm

FT-IR , XRD and SEM are used to characterise the product

Used for the preparation of nano particle sized LiBiO2

Requirements

Lithium Nitrate

bismuth Nitrate

Urea (igniter-fuel)

Glycerol (binding material)

Lithium Nitrate and Bismuth Nitrate are mixed together to form a uniform mixture

Required quantities of urea and glycerol are added to form a homogeneous paste

Pre-heated at 150-2000c to form a dried mass

Calcined at 4600c for 5 hours

Nanoparticles of LiBiO2 are obtained

Conducted in steel pressure vessels called autoclaves with or without teflon liners

Under controlled temperature and/or pressure with the reaction in aqueous solution

Widely used for the production of small particles in ceramics industry

Used to prepare nanoparticles of TiO2

AUTOCLAVE

Hydrothermal treatment of peptized precipitate of a titanium precursor with water

Precipitates are prepared by adding 0.5M isopropanolsolution of titanium butoxide into deionisde water

They are peptized at 700C for 1 hour in the presence of tetraalkyl ammonium hydroxide (peptizer)

Filtration and treatment at 2400C for 2 hours

Obtained powder are washed with deionised water and absolute alcohol

Dried at 600C

Under the same concentrations of the peptizer,theparticle size decreased with increasing alkyl chain length

The peptizers and their concentrations influenced the morphology of the particle

Utilized in industries to perform size reduction

Induce structural changes and chemical reactions by mechanical energy rather than thermal energy,reaction are possible at room temperature and so non-equilibrium in nature

The milling process embraces a complex mixture of fracturing, grinding, high speed plastic deformation, cold welding,thermalshock, intimate mixing etc

. Produced a large range of nanoscaled materials – nanocrystalline

materials, nanoparticles, nanocomposites ,nanotubes,nanowiresand nanorods

Mechanical Alloying (MA)

Mechanical Milling (MM)

Mechanochemical Synthesis (MS)

Mixtures of powders are milled together

Material transfer is involved

A homogeneous alloy is obtained

Only powder with uniform composition is milled

No material transfer is involved

A special MA process

Chemical reaction between the powders take place during milling

Grain refinement and chemical reactions take place at low temperature under far from equilibrium conditions

Cold welding and Agglomeration during milling opposes MA and MM

Nanocomposite mixtures formed during mechanochemical reaction can be further processed into nanoscale particles

Nano composite of Fe and NaCl was obtained by milling FeCl3 and sodium metal

FeCl3 + 3 Na → Fe + 3 NaCl

Simple washing after milling dissolves NaCl and nanoparticles of Fe can be obtained

Excellent versatility

Scalability

Cost effectiveness

TKMM COLLEGE NANGIARKULANGARA