the branch of technology that deals with dimensions and tolerances of less than 100 nanometres, especially the manipulation of individual atoms and molecules.

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4. SIZE
A meter is about the distance from the tip of your
nose to the end of your hand (1 meter = 3.28 feet).
Millimeter- One thousandth of meter.(10-3
m)
Micron: a micron is a millionth of a meter (or) one
thousandth of millimeter (10-6
m)
Nanometer:
A nanometer is one thousandth of a micron (10–9
m)
(or) a billionth of a meter. ie.,one billion
nanometers in a meter.

6. • Composites made from particles of nano-size ceramics or metals
smaller than 100 nanometers can suddenly become much stronger
than predicted by existing materials-science models.
• For example, metals with a so-called grain size of around 10
nanometers are as much as seven times harder and tougher than
their ordinary counterparts with grain sizes in the micro meter
range.
• The Nano particles affects many properties such as
Melting point
Boiling point
Band gap
Optical properties
Electrical properties
Magnetic properties
• .Even the structure of materials changes with respect to Size

7. The properties of materials can be different at the Nanoscale for two
main reasons:
First, Nanomaterials have a relatively larger surface area when
compared to the same mass of material produced in a larger form.
Nano particles can make materials more chemically reactive and affect
their strength or electrical properties.
Nanoscale materials are divided into three category,
1. Zero dimension – length , breadth and heights are confined at single
point. (for example, Nano dots)
2. One dimension – It has only one parameter either length (or) breadth
(or) height ( example:very thin surface coatings)
3. Two dimensions- it has only length and breadth (for example,
nanowires and nanotubes)
4. Three dimensions -it has all parameter of length, breadth and height.
(for example, Nano Particles).
Second, quantum effects can begin to dominate the behaviour of
matter at the Nanoscale

8. What do you mean by Nano Particles ?
Nano Particles are the particles of size between 1 nm to 100 nm
Nanometer - One billionth (10-9
) of a meter
• The size of Hydrogen atom 0.04 nm
• The size of Proteins ~ 1-20 nm
• Feature size of computer chips 180 nm
• Diameter of human hair ~ 10 µm
At the nanoscale, the physical, chemical, and biological properties
of materials differ in fundamental and valuable ways from the
properties of individual atoms and molecules or bulk matter
• 1 nm is only three to five atoms wide.
• ~40,000 times smaller than the width of an average human hair

9. Noparticles are of interest because of the new properties (such as
chemical reactivity and optical behaviour) that they exhibit compared
with larger particles of the same materials.
For example, titanium dioxide and zinc oxide become transparent at
the nanoscale and have found application in sunscreens.
Nanoparticles have a range of potential applications:
In the short-term application such as in cosmetics, textiles and
paints.
In the longer term applications such as drug delivery where they
could be to used deliver drugs to a specific site in the body.
Nanoparticles can also be arranged into layers on surfaces, providing
a large surface area and hence enhanced activity, relevant to a
range of potential applications such as catalysts.
Why Nano Particles ?

10. • Examples
- Carbon Nanotubes
- Proteins, DNA
- Single electron transistors
AFM Image of DNA
Carbon Nanotubes

11. Nanotechnology deals with the creation of USEFUL
materials, devices and systems using the particles of
nanometer length scale and exploitation of NOVEL
properties (physical, chemical, biological) at that length
scale

12. • Nanoparticles
• Nanocapsules
• Nanofibers
• Nanowires
• Fullerenes (carbon 60)
• Nanotubes
• Nanosprings
• Nanobelts
• Quantum dots
• Nanofluidies
Based on the size and shape, the Nano materials are classified as
follows

13. Quantum well
• It is a two dimensional system
• The electron can move in two directions and restricted in one
direction.
Quantum Wire
• It is a one-dimensional system
• The electron can move in one direction and restricted in two
directions.
Quantum dot
• It is a zero dimensional system
• The electron movement was restricted in entire three
dimensions

14. WHY CALLED QUANTUM ?
• Because, the electronic property is quantized
• The spatial distance is very very small

15. substrateSemiconductor
growth (single
layer)

18. Quantum wire
Quantum wires are ultra fine wires or linear arrays of Nano
dots, formed by self-assembly
They can be made from a wide range of materials such as
Semiconductor Nanowires made of silicon, gallium nitride and
indium phosphide.
Nanowires have potential applications in
1. In high-density data storage, either as magnetic read heads or as
patterned storage media
2. In electronic and opto-electronic Nanodevices, for metallic
interconnects of quantum devices and Nanodevices.
Nanowires can be prepared by growth techniques such as
1. Chemical Vapour deposition (CVD)
2. Electroplating

19. We need two dimension to calculate area of conducting material,
but not present in quantum wire
In quantum wire, Two dimensions are reduced and one
dimension remains large
Therefore, the electrical resistivity of quantum wire can be
calculated using conventional formula as follows,
Quantum wire cont…

20. General properties of Nanowire
 Diameter – 10s of nanometers
 Single crystal formation -- common crystallographic
orientation along the nanowire axis
 Minimal defects within wire
 Minimal irregularities within nanowire arrays
Some example of Nanowire

21. Magnetic nanowires
 Example: Cobalt, gold, copper and cobalt-copper
nanowire arrays
 Important for storage device applications
 Electrochemical deposition is the fabrication
technique
 <20 nm diameter nanowire arrays can be fabricated
by electrochemical deposition
Cobalt nanowires on Si substrate
(UMass Amherst, 2000)

22. In quantum dot all the three dimensions are reduced to zero
Quantum dot

23. Dimension Variation ⇒

24. Properties of nanoparticlesProperties of nanoparticles

26. The melting point decreases dramatically as the particle size
gets below 5 nm
Source: Nanoscale Materials in Chemistry, Wiley, 2001
Melting Point

27. Band gap
The band gap is increases with reducing the size of the
particles

28. Surface Area
The total surface area (or) the number of surface atom increases
with reducing size of the particles

29. • For semiconductors such as ZnO, CdS, and Si, the bandgap
changes with size
- Bandgap is the energy needed to promote an electron
from the valence band to the conduction band
- When the bandgaps lie in the visible spectrum, changing
bandgap with size means a change in color
• For magnetic materials such as Fe, Co, Ni, Fe3O4, etc., magnetic
properties are size dependent
- The ‘coercive force’ (or magnetic memory) needed to
reverse an internal magnetic field within the particle is
size dependent
- The strength of a particle’s internal magnetic field can be
size dependent

31. • Because of their small size, nanoscale devices can readily
interact with biomolecules on both the surface of cells and
inside of cells.
• By gaining access to so many areas of the body, they have the
potential to detect disease and the deliver treatment.
1. Nanotechnology Applications in Medicine
• Nanoparticles can can deliver drugs directly to
diseased cells in your body.
• Nanomedicine is the medical use of molecular-
sized particles to deliver drugs, heat, light or other
substances to specific cells in the human body.

32. • Quantum dot- that identify the location of cancer
cells in the body.
• Nano Particles - that deliver chemotherapy drugs
directly to cancer cells to minimize damage to healthy
cells.
• Nanoshells - that concentrate the heat from infrared
light to destroy cancer cells with minimal damage to
surrounding healthy cells.
• Nanotubes- used in broken bones to provide a
structure for new bone material to grow.

33. Nano shells as Cancer Therapy
Nano shells are injected into cancer area and they recognize
cancer cells. Then by applying near-infrared light, the heat
generated by the light-absorbing Nano shells has successfully
killed tumor cells while leaving neighboring cells intact.

37. • In this diagram (next page), Nano sized sensing wires are laid
down across a micro fluidic channel. As particles flow through the
micro fluidic channel, the Nanowire sensors pick up the molecular
identifications of these particles and can immediately relay this
information through a connection of electrodes to the outside
world.
• These Nanodevices are man-made constructs made with carbon,
silicon Nanowire.
• They can detect the presence of altered genes associated with
cancer and may help researchers pinpoint the exact location of
those changes
Nanowires – used as medical sensor

38. Past
Shared computing thousands of
people sharing a mainframe computer
Present
Personal computing
Future
Ubiquitous computing thousands of computers sharing each
and everyone of us; computers embedded in walls, chairs, clothing,
light switches, cars….; characterized by the connection of things in
the world with computation.
2. Nano Computing Technology

39. 3. Sunscreens and Cosmetics
• Nanosized titanium dioxide and zinc oxide are currently used in
some sunscreens, as they absorb and reflect ultraviolet (UV) rays.
• Nanosized iron oxide is present in some lipsticks as a pigment.
4. Fuel Cells
The potential use of nano-engineered membranes to intensify
catalytic processes could enable higher-efficiency, small-scale fuel
cells.
5. Displays
• Nanocrystalline zinc selenide, zinc sulphide, cadmium sulphide and
lead telluride are candidates for the next generation of light-emitting
phosphors.
• CNTs are being investigated for low voltage field-emission displays;
their strength, sharpness, conductivity and inertness make them
potentially very efficient and long-lasting emitters.

40. 6. Batteries
• With the growth in portable electronic equipment (mobile phones,
navigation devices, laptop computers, remote sensors), there is great
demand for lightweight, high-energy density batteries.
• Nanocrystalline materials are candidates for separator plates in
batteries because of their foam-like (aerogel) structure, which can
hold considerably more energy than conventional ones.
• Nickel–metal hydride batteries made of nanocrystalline nickel and
metal hydrides are envisioned to require less frequent recharging
and to last longer because of their large grain boundary (surface)
area.
7. Catalysts
In general, nanoparticles have a high surface area, and hence provide
higher catalytic activity.

41. 8. Magnetic Nano Materials applications
• It has been shown that magnets made of nanocrystalline yttrium–
samarium–cobalt grains possess unusual magnetic properties due
to their extremely large grain interface area (high coercivity can
be obtained because magnetization flips cannot easily propagate
past the grain boundaries).
• This could lead to applications in motors, analytical instruments
like magnetic resonance imaging (MRI), used widely in hospitals,
and microsensors.
• Nanoscale-fabricated magnetic materials also have applications in
data storage.
• Devices such as computer hard disks storage capacity is increased
with Magnetic Nano materials

42. .
• Unfortunately, in some cases, the biomedical metal alloys may wear
out within the lifetime of the patient. But Nano materials increases
the life time of the implant materials.
• Nanocrystalline zirconium oxide (zirconia) is hard, wear resistant,
bio-corrosion resistant and bio-compatible.
• It therefore presents an attractive alternative material for implants.
• Nanocrystalline silicon carbide is a candidate material for artificial
heart valves primarily because of its low weight, high strength and
inertness.
9. Medical Implantation
10. Water purification
•Nano-engineered membranes could potentially lead to more energy-
efficient water purification processes, notably in desalination process.

43. 11. Military Battle Suits
• Enhanced nanomaterials form the basis of a state-of- the-art
‘battle suit’ that is being developed.
• A short-term development is likely to be energy-absorbing
materials that will withstand blast waves;
• longer-term are those that incorporate sensors to detect or
respond to chemical and biological weapons (for example,
responsive nanopores that ‘close’ upon detection of a
biological agent).

44. PHYSISORPTION CHEMISORPTION
WEAK, LONG RANGE BONDING
Van der Waals interactions
STRONG, SHORT RANGE BONDING
Chemical bonding involved.
NOT SURFACE SPECIFIC
Physisorption takes place between all
molecules on any surface providing the
temperature is low enough.
SURFACE SPECIFIC
E.g. Chemisorption of hydrogen takes place on
transition metals but not on gold or mercury.
ΔHads = 5 ….. 50 kJ mol-1 ΔHads = 50 ….. 500 kJ mol-1
Non activated with equilibrium achieved
relatively quickly. Increasing temperature
always reduces surface coverage.
Can be activated, in which case equilibrium can
be slow and increasing temperature can favour
adsorption.
No surface reactions. Surface reactions may take place:-
Dissociation, reconstruction, catalysis.
MULTILAYER ADSORPTION
BET Isotherm used to model adsorption
equilibrium.
MONOLAYER ADSORPTION
Langmuir Isotherm is used to model adsorption
equilibrium.
Physisorption vs Chemisorption
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