preparation of nano particles
TRANSCRIPT
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TKMM COLLEGE NANGIARKULANGARA
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SOL-GEL SYNTHESIS
COLLOIDAL PRECIPITATION
CO-PRECIPITATION
COMBUSTION TECHNIQUE
HYDROTHERMAL TECHNIQUE
HIGH ENERGY BALL MILLING
SONOCHEMISTRY
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Wet chemical technique Chemical solution deposition
For gel like properties particle density shoud be increased by removing significant amount of solvent
SOL GEL
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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)
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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
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Synthesis of nano particles of gold,silver
Tetrachloroauric acid
trisodium citrate(reductant)
Gold particles (purple colour)
HAu+3Cl4 Au0
Frens-Turkevich method
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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
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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
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Morphology of Fe3O4 powder consists of cubic phase with size of 24 nm
FT-IR , XRD and SEM are used to characterise the product
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Used for the preparation of nano particle sized LiBiO2
Requirements
Lithium Nitrate
bismuth Nitrate
Urea (igniter-fuel)
Glycerol (binding material)
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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
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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
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AUTOCLAVE
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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
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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
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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
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Mechanical Alloying (MA)
Mechanical Milling (MM)
Mechanochemical Synthesis (MS)
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Mixtures of powders are milled together
Material transfer is involved
A homogeneous alloy is obtained
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Only powder with uniform composition is milled
No material transfer is involved
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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
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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
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Excellent versatility
Scalability
Cost effectiveness
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TKMM COLLEGE NANGIARKULANGARA