Nanochemistry

NANOCHEMISTRY
 Nanomaterials are materials having at least one of

their dimensions (length or width or height) in the
range of 1-100 nm. This range is called the nanoscale
or nanoscopic or nanometric range.
 1 nm = 10-9m = 10Å
Properties of Nanomaterials
 Nanomaterials show unique properties like increased

strength, toughness, hardness, ductility, melting
point, efficient electrical properties, magnetic
properties, catalytic properties, optical properties,
and so on as compared to bulk materials.
 1. Mechanical properties of nanomaterials:
due to the increased number of surface atoms and
interfaces, which in turn leads to increased density of
defects like grain boundaries, dislocations, triple
junctions, etc.
 The properties such as hardness and elastic
modulus,fracture toughness,scratch
resistance,fatigue strebth and hardness of
nanaomaterials follow Hall-Petch relationship
(increases with decreasing particle size)
2. Thermal properties of nanomaterials:
Due to the high density of defects compared to bulk materials,
nanostructured materials have a higher thermal expansion
coefficient, measures how the size of the material changes as a
function of temperature.
3. Electrical properties of nanomaterials: Nanomaterials

have lower thermal and electrical conductivities than bulk
materials. The classical free electron theory of metals states that
the movement of electrons within a metallic solid lead
to electrical conductivity. Nanomaterials have a high density of
grain boundaries, which makes electric-phonon and phonon-
phonon scattering effective and reduces conductivity
4. Magnetic properties:
 Nanomaterials have greater value of maganetization and magnetic
anisotropy in comparison with their bulk counter parts.
 Due to the lowered size effect, the value of both saturation
magnetization and magnetic coercivity attributes has increased.
 If the external magnetic field is unable to further alter the

magnetization of a material, it is said to be in a magnetically
saturated state.
 The amount of magnetic field required to get a ferromagnetic

material’s saturation magnetization to zero is known as magnetic
coercivity.
5. Catalytic properties:
 When the particle size of nanaomaterial is reduced
then the surface area and number of surface atoms
are increased, which causes an increase in the
catalytic activity of nanomaterials.
6. Optical properties :
 nanomaterials exhibit distinctive optical
characteristics such as greater scattering, absorption,
and luminescence.
 The shape and size of nanoparticles can be altered to
change their optical properties
Classification of Nanomaterials
 On the basis of dimensions, they are classified as:
 Zero-dimensional nanomaterials: Such materials have all three length

scales Lx (length along X-axis), Ly (length along Y-axis, and Lz (length along Z-
axis) in the nanoscopic range. Examples: Quantum dots, fullerens,gold
nanoparticles,metallic nanoclusters, nanosphere, nanorods, nanocubes, etc.
 One-dimensional nanomaterials: In such materials, one of the dimensions

is out of the nanoscopic range. Nanowires, nanotubes, polymeric nanowires,etc.
are some examples of one-dimensional nanomaterials.
 Two-dimensional nanomaterials: In these materials, any two dimensions
are out of the nanoscopic range. Examples: Nanofilms, nanosheets, nano-
coatings, graphene sheets and so on.
 Three-dimensional nanomaterials: In these materials, all three

dimensions are out of the nanoscopic range. Dendrimers,polycrystalline and
liposomes are some examples.
Dimensional nanomaterials
Methods of synthesis
A. Physical methods B. Chemical methods
 1. Mechanical Method  1. Sol-gel Method

(Ball milling & Melt mixing)  2. Sonochemical
 2. Pulse Laser Ablation Synthesis
 3. Pulsed Wire Discharge
 3. Co-precipitation
Method
 4. Chemical Vapor
Method
Deposition  4. Inert Gas
 5. Laser Pyrolysis Condensation Method
 6. Ionized Cluster Beam  5. Hydrothermal
Deposition Synthesis
Physical Methods
Ball milling Melt Mixing
 The container contains hard  Mixing molten streams of metals

balls made up of steel or at high velocity with turbulence
carbide. Nanocrystalline Co, Cr, form nanoparticles.
W, Ag-Fe, are synthesized using Nanoparticles get arrested in a
this method. The ratio of balls glass.
to materials is 2:1. The  Ex: A melted stream of Cu-B and
container is filled with inert gas a heated stream of Ti forms
or air and is rotated at high nanoparticles of TiB2
speed around the central axis.
The materials are pressed
between the walls of the
container and balls. The speed
and duration of milling play a
significant role in synthesizing
nanoparticles of optimum size
Ball milling
2.Pulse laser ablation
 The target sample is placed inside a vacuum
chamber. The high-pulsed laser beam is focused on
the sample and plasma is generated, which is
formerly transformed into a colloidal solution of
nanoparticles.
3. Pulsed wire discharge method
 A metal wire is vaporized by a pulsated current to
yield a vapour, which is then cool by ambient gas to
procedure nanoparticles. This scheme has possibly a
high fabricationspeed and high energy productivity.
 Pulsed wire
discharge method
4. Chemical vapor deposition
 A thin film of gaseous reactant is deposited on the
substrate at around 300-1200 °C & the applied
pressure varies in the range of 100-105Pa.
 Advantages:-
o Stiff
o uniform
o robust
o highly pure nanoparticles are manufactured.
 Substrates are heated by two cold wall and hot wall
techniques.
 Different types of CVD:-
 Metallo Organic CVD
 Atomic Layer Epitaxy
 Vapor Phase Epitaxy
 Plasma Enhanced CVD
 Gas pressure and the substrate temperature
ultimately affects the growth rate and quality of film.
Chemical vapor deposition
5. Laser pyrolysis
 The process of synthesis of nanoparticles by using a
laser is known as laser pyrolysis. An intense laser
beam is focused to decompose the mixture of
reactant gases in the existence of some inactive gas
like helium or argon. The gas pressure shows a
significant part in determining the particle sizes and
their distribution.
6. Ionised cluster beam deposition
 The main aim of this method is to obtain high-quality single-
crystalline thin films.
 The arrangement comprises a source of evaporation, a nozzle
through which material can expand into the chamber, an
electron beam to ionize the clusters, an arrangement to
accelerate the clusters, and a substrate on which nanoparticle
film can be deposited, all housed in a suitable vacuum
chamber.
 After impact with an electron beam, collections get ionized.
Due to applied hastening voltage, the clusters are focused near
the substrate. It is likely to control the energy with which the
clusters hit the substrate by monitoring the accelerating
voltage.
Nanomaterials and Nanoparticles
 All nanoparticles are

nanomaterials but not
all nanomaterials are
nanoparticles.
 Nanoparticles are
nanomaterials having all
three dimensions in the
range of 1-100 nm i.e. they
are zero-dimensional
nanomaterials.
Application of Nanomaterials
 Electronics and Nanoelectronics

 Nanosensors and nanoprobes
 Nanocatalysts
 Food and agriculture industry
 Personal care products and consumer goods
 Automobile industry
 Water treatment and the environment
 Medical diagnostics and related applications
 Textiles
 Paints
 Energy sector applications
 Space applications
 Structural applications
 Nanotechnology in defense, and so on.

Nanochemistry

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NANOCHEMISTRY

 Nanomaterials are materials having at least one of

 Nanomaterials show unique properties like increased

3. Electrical properties of nanomaterials: Nanomaterials

 If the external magnetic field is unable to further alter the

 The amount of magnetic field required to get a ferromagnetic

 On the basis of dimensions, they are classified as:

 Zero-dimensional nanomaterials: Such materials have all three length

 One-dimensional nanomaterials: In such materials, one of the dimensions

 Three-dimensional nanomaterials: In these materials, all three

A. Physical methods B. Chemical methods

 1. Mechanical Method  1. Sol-gel Method

Ball milling Melt Mixing

 The container contains hard  Mixing molten streams of metals

 All nanoparticles are

 Electronics and Nanoelectronics

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