This document discusses nanomaterials and nanotechnology. It defines nanomaterials as materials with structured components less than 100nm in at least one dimension. It describes four main types of nanomaterials: carbon-based, metal-based, dendrimers, and composites. The properties of nanoparticles differ from bulk materials due to their high surface area to volume ratio and quantum confinement effects. Nanoparticles are synthesized using top-down or bottom-up approaches such as sol-gel methods, chemical vapor deposition, and pulsed laser deposition. Nanotechnology has applications in areas like energy, electronics, medicine, and consumer goods.

1. DONE BY
Aluru Jaideep Reddy
Vardhaman college
Of engineering

2. Nanomaterials
 Nanomaterials are defined as those materials which have structured
components with size less than 100nm atleast in one dimension.
 Materials that are nanoscale in one dimension are layers such as thin films
or surface coatings.
 Materials that are nanoscale in two dimensions are nano wires and nano
tubes.
 Materials that are nanoscale in three dimensions are precipitates colloids
and quantum dots.
 The nanostructured materials are materials where the dimensions are in the
range of 1 to 100nm (i.e. from the size of the atom to the wavelength of the
light.) Nano Science
Nanoscience can be defined as the study of phenomena and
manipulation of materials at atomic, molecular and macromolecular scales,
where properties differ significantly from those at a large scale.
Nanotechnology
Nanotechnology can be defined as the design, characterization,
production and application of structures, devices and systems by controlling
shape and size at the nanometre scale.

3. TYPES OF NANOMATERIALS
Most current Nanomaterials could be organized into four types:
1. Carbon Based Materials
2. Metal Based Materials
3. Dendrimers
4. Composites
CARBON BASED NANOMATERIALS
 These nanomaterials are composed mostly of carbon, most
commonly taking in the form of hollow spheres, ellipsoids, or
tubes.
 Spherical and ellipsoidal carbon nanomaterials are referred to as
fullerenes, while cylindrical ones are called nanotubes.
 These particles have many potential applications, including
improved films and coatings, stronger and lighter materials, and
applications in electronics.

4. METAL BASED NANOMATERIALS
 These nanomaterials include quantum dots, nanogold, nanosilver and
metal oxides, such as titanium dioxide.
 A quantum dot is a closely packed semiconductor crystal comprised of
hundreds or thousands of atoms, and whose size is on the order of a few
nanometers to a few hundred nanometers. Changing the size of quantum
dots changes their optical properties.
DENDRIMERS
 These nanomaterials are nanosized polymers built from branched units.
The surface of a dendrimer has numerous chain ends, which can be
tailored to perform specific chemical functions. This property could
also be useful for catalysis.
 Three-dimensional dendrimers contain interior cavities into which other
molecules could be placed, they may be useful for drug delivery.
COMPOSITES
 Composites combine nanoparticles with other nanoparticles or with larger,
bulk-type materials. Nanoparticles, such as nanosized clays, are already
being added to products ranging from auto parts to packaging materials, to
enhance mechanical, thermal, barrier, and flame-retardant properties.

5. Why the properties of nanoparticles are different?
Two principal factors cause the properties of nanomaterials to differ
significantly from other materials.
1. Increase in surface area to volume ratio
2. Quantum confinement effects
These factors can change the properties such as reactivity, strength and
electrical characteristics.
1. Increase in surface area to volume ratio
 Nanomaterials have a relatively larger surface area when compared to the same
volume of the material produced in a larger form.
 Let us consider a sphere of radius r,
Its surface area = 4πr2
Its volume = (4/3) πr3
Surface area to its volume ratio = 3/r.
Thus when the radius of the sphere decreases, its surface area to volume ratio
increases.

6.  Let us consider another example. For one cubic volume, surface area is 6 m2.
When it is divided into 8 pieces its surface area becomes 12 m2. when the same
volume is divided into 27 pieces its surface area becomes 18 m2. Thus we find
that when the given volume is divided into smaller pieces its surface area
increases. Hence as particle size decreases its surface area increases.
(Surface area of cube = 6a2)
 Thus nanoparticles have a greater surface area per given volume compared
with large particles. It makes materials more reactive.
 As growth and catalytic chemical reactions occur at surfaces, this means
that a given mass of material in nanostructure form will be much more
reactive than the same mass of material made up of larger particles. This
affects their strength or electrical properties.

7. 2. Quantum confinement effects
 When atoms are isolated, the energy levels are discrete. When very large number
of atoms are closely packed to form a solid, the energy levels split and form bands.
Nanomaterials represent intermediate stage.
 We have studied the problems of particles in a potential well as well as in a
potential box. When dimensions of such potential boxes or wells are of the order of
deBroglie wavelength of electrons, energy levels of electrons change. This effect is
called Quantum confinement.
 When the material is in sufficiently small size typically 10 nm or less, organization
of energy levels into which electrons can climb or fall change. Specifically, the
phenomenon results from electrons and holes being squeezed into a dimension that
approaches a critical quantum measurement, called the “exciton Bohr radius”.
 These can affect the optical, electrical and magnetic behaviour of materials,
particularly as the structure or particle size approaches the smaller end of the
nanoscale.

8. (PROPERTIES OF NANOMATERIALS)
NANOSCALE SIZE EFFECT
• Manifestation of novel phenomena and properties,
including changes in:
- Physical Properties (e.g. melting point)
- Chemical Properties (e.g. reactivity)
- Electrical Properties (e.g. conductivity)
- Mechanical Properties (e.g. strength)
- Optical Properties (e.g. light emission)
- Magnetic Properties (e.g. Coercivity)

11. Chemical Properties
Mechanical Properties

16. HOW TO SYNTHESIZE?
 TOP DOWN APPROACH
 SOL-GEL METHOD
 BOTTOM UPAPPROACH
 CVD
 PVD
 PLVD
Approaches
 Top-down –
Breaking down matter into more basic building
blocks. Frequently uses chemical or thermal methods.
 Bottoms-up –
Building complex systems by combining simple
atomic-level components.

19. Advantages
 high growth rates possible
 can deposit materials which
are hard to evaporate
 good reproducibility
 can grow epitaxial films
Disadvantages
 high temperatures
 complex processes
 toxic and corrosive gasses

20.  The sol gel process is a wet chemical technique i.e., chemical
solution deposition technique used for the production of high purity
and homogeneous nanomaterials, particularly metal oxide nano
particles.
 The idea behind sol-gel synthesis is to “dissolve” the compound in
a liquid in order to bring it back as a solid in a controlled manner.
 The starting material from a chemical solution leads to the
formation of colloidal suspensions known as ‘sol’.
 Then the sol evolves towards the formation of an inorganic network
containing a liquid phase called the ‘gel’.
 The removal of the liquid phase from the sol yields the gel.
 The particle size and shape are controlled by the sol/gel transitions.
 The thermal treatment (firing/calcinations) of the gel leads to
further poly condensation and enhances the mechanical properties
of the products, i.e., oxide nanoparticles.

21.  The precursors for synthesizing the colloids are metal alkoxides and metal chlorides.
 The starting material is processed with water or dilute acid in an alkaline solvent.
 The material undergoes a hydrolysis and poly condensation reaction which leads to the
formation of colloids.
 The colloid system composed of solid particles dispersed in a solvent contains particles of
size from 1nm to 1mm.
 The sol is then evolved to form an inorganic network containing liquid phase (gel).
 The schematic representation of the synthesis of nanoparticles using the sol gel method is
shown in Fig.
 The sol can be further processed to obtain the substrate in a film, either by dip coating or
spin coating, or cast into a container with desired shape or powders by calcinations.
 The chemical reaction which takes place in the sol gel metal alkoxides M (OR)2 during the
hydrolysis process and condensation is given below:
M-O-R +H 2 O M-OH + R-OH (Hydrolysis)
M-O-H + R-O-M M-O-M + R-OH (Condensation)

23.  The sol-gel method is an interesting, cheap and low
temperature technique which is used to produce a range
of nanoparticles with controlled chemical compositions.
 One can produce the aero gel, a highly porous material
like glass and glass ceramics, at a very low temperature
by controlling the process parameters.
 The sol gel derived nanoparticles finds wide spread
applications in various fields like optics, electronics,
energy, space, bio sensors and drug delivery.
 Controlling the growth of the particles is difficult.
 Stopping the newly formed particles from agglomeration is also
difficult

24. The materials of interest are evaporated and hence, the atoms or
molecules are in gas phase. The gas phase atoms or molecules are
used to obtain the nanostructured materials in any one of the methods,
namely,
1. Evaporation
2. Sputtering
3. Ion plating
4. Laser ablation
Let us discuss the experimental set-up used for the synthesis of
nanostructured materials in the evaporation method.

25.  The schematic representation of the experimental set-up
used for the synthesis of nanomaterials by evaporation is
shown in figure.
 It consists of a bell jar, in which an inert gas or reactive
gas is filled after vacuum. The materials to be evaporated
are placed in the crucibles and are heated either by
resistance or an electron gun until sufficient vapour
develops.
 The evaporated atoms or molecules are allowed to
condense on a cold finger which is cooled externally by
liquid N2. The nanoparticles on the cold finger is scraped
by the scraper and then collected to the piston anvil
through a funnel.

27. Introduction
 Pulsed-laser vapour deposition (PLVD) has gained a great deal of attention in the
past few years for its ease of use and success in depositing materials of complex
stoichiometry.
 PLVD was the first technique used to successfully deposit a superconducting
YBa2Cu3O7-d thin film. Since that time, many materials that are normally difficult
to deposit by other methods, especially multi-element oxides, have been
successfully deposited by PLVD.
 Synthesis of Buckminster fullerenes and nanopowders have also been reported by
using PLVD.

28. THE MECHANISM OF PLD
 The principle of pulsed laser deposition, in contrast to the simplicity
of the system set-up, is a very complex physical phenomenon.
 It does not only involve the physical process of the laser-material
interaction of the impact of high-power pulsed radiation on solid
target, but also the formation plasma plume with high energetic
species and even the transfer of the ablated material through the
plasma plume onto the heated substrate surface.
 Thus the thin film formation process in PLVD generally can be
divided into the following four stages.
1. Laser radiation interaction with the target
2. Dynamic of the ablation materials
3. Deposition of the ablation materials with the substrate
4. Nucleation and growth of a thin film on the substrate surface
Each stage in PLVD is critical to the formation of quality epitaxial
crystalline, stoichiometric, uniform and small surface roughness thin
film.

29. THE ADVANTAGES OF PLD
The main advantages of Pulsed Laser Deposition are:
 conceptually simple: a laser beam vaporizes a target surface,
producing a film with the same composition as the target.
 versatile: many materials can be deposited in a wide variety of
gases over a broad range of gas pressures.
 cost-effective: one laser can serve many vacuum systems.
 fast: high quality samples can be grown reliably in 10 or 15
minutes.
 scalable: as complex oxides move toward volume production.

30. Medicine Consumer Goods
Smaller, faster, more
energy efficient and
powerful computing
and other IT-based
systems
More efficient and cost
effective technologies for
energy production
 Solar cells
 Fuel cells
 Batteries
 Bio fuels
• Foods and beverages
−Advanced packaging materials,
sensors, and lab-on-chips for
food quality testing
• Appliances and textiles
−Stain proof, water proof and
wrinkle free textiles
• Household and cosmetics
− Self-cleaning and scratch free
products, paints, and better
cosmetics
• Cancer treatment
• Bone treatment
• Drug delivery
• Appetite control
• Drug development
• Medical tools
• Diagnostic tests
• Imaging

31. ENDLESS APPLICATIONS OF
NANOTECHNOLOGY
 nanomedicines to fight diseases.
 Nanorobots.
 Less pollution and automatic clean up.
 More efficient solar cells.
 Carbon nanotubes.
 Ultra light materials for construction.
 Nanorobots in military applications.
 Self replicating and self repairing machinery .
 A supercomputer no bigger than a human cell.
 High density data storage.
And the list goes on………