This document discusses various techniques for synthesizing nanoparticles, including sol-gel synthesis, colloidal precipitation, co-precipitation, combustion technique, hydrothermal technique, high energy ball milling, and sonochemistry. It provides details on specific methods like the Frens method for synthesizing gold nanoparticles, co-precipitation reaction for iron oxide nanoparticles using FeCl3 and benzene tetracarboxylic acid, combustion synthesis using lithium nitrate and bismuth nitrate with urea and glycerol, and hydrothermal treatment for titanium dioxide nanoparticles. The advantages of these techniques in producing nanoparticles at low temperatures and with good control of properties are highlighted.
SOL-GEL SYNTHESIS
COLLOIDAL PRECIPITATION
CO-PRECIPITATION
COMBUSTIONTECHNIQUE
HYDROTHERMALTECHNIQUE
HIGH ENERGY BALL MILLING
SONOCHEMISTRY
3.
Wet chemicaltechnique
Chemical solution deposition
For gel like properties particle density shoud be
increased by removing significant amount of
solvent
SOL GEL
4.
Sedimentation
Centrifugation
Drying process (shrinkage and densification)
Thermal treatment/firing process (favour
polycondensation , enhance mechanical properties
and structural stability via final
sintering,densification and grain growth)
5.
Densification canbe 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
Simple andlow cost process
Applicable to preparation of magnetic nano
particles
Iron oxide nano particles are synthesised by
co-precipitation reaction of FeCl3 and
1,2,4,5-benzene tetracarboxylic acid
10.
FeCl3, NaOHand 1,2,4,5-benzene tetracarboxylic
acid 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
11.
Morphology ofFe3O4 powder consists of
cubic phase with size of 24 nm
FT-IR , XRD and SEM are used to
characterise the product
Lithium Nitrateand 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
14.
Conducted insteel 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
Hydrothermal treatmentof peptized precipitate of a titanium
precursor with water
Precipitates are prepared by adding 0.5M isopropanol
solution 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
17.
Under thesame concentrations of the peptizer,the
particle size decreased with increasing alkyl
chain length
The peptizers and their concentrations
influenced the morphology of the particle
19.
Utilized inindustries 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,nanowires
and nanorods
Mixtures ofpowders are milled together
Material transfer is involved
A homogeneous alloy is obtained
22.
Only powderwith uniform composition is milled
No material transfer is involved
23.
A specialMA 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
24.
Nanocomposite mixturesformed 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