Nano-materials as Engineering Materials for new age

1. ENGINEERING
MATERIALS
By
Dr. Jagadale S.K
Assistant Prof. Engineering Chemistry
S.B.Patil College Of Engineering,
Indapur

2.  Nanomaterials are the materials in which
particle size ranges from 1 nm to 100nm.
 Study and use of these particles called as
Nanotechnology.
 They can be found in such things as sunscreens
(ZnO), cosmetics, sporting goods, stain-resistant
clothing, tires, electronics, as well as many other
everyday items, and are used in medicine for
purposes of diagnosis, imaging and drug delivery.
Introduction to Nanomaterials

3. Classification of Nanomaterials
1. Zero dimensional nanomaterials
Def: The nanomaterials have all dimensions within nanoscale range and larger than 100 nm.
Properties: crystalline or polycrystalline in structure, crystalline or amorphous in nature and exist
individually or in matrix.
Ex. Quantum dots, core shell, heterogeneous particles, hollow spheres etc.
Applications: LED’s solar cells, lasers etc.
2. One dimensional nanomaterials
Def: The nanomaterials have two dimension within nanoscale range and one dimension beyond
nanoscale.
Ex. Nanowires, nanorods, nanotubes, nanofilms, Nano ribbons etc.
Applications: Thin films used in Si IC industry, fuel cells and catalysis.
3. Two dimensional nanomaterials
Def: The nanomaterials have one dimension within nanoscale range and two dimension beyond
nanoscale.
These are in the form of layers & used as single layer or multilayer.
Ex. CNT’s, Nanoplates, Nanosheets, Nanowalls, Nanodiscs etc.
Applications: Nanodevices, Sensors, photocatalysis, Nanoreactors
CNT’s: SW or MW, diameter in nm and microns to mm in length, flexible, mechanically strong,
and conductors.
Used in reinforced composites, Sensors, nanoelectronics, display devices etc.

4. 4. Three dimensional nanomaterials
Def: These are the bulk nanomaterials which are not confined to
nanoscale in any dimension. (3 dimensions above 100nm scale).
Properties: Nanocrystalline structure, larger surface area due to
quantum effects.
Bulk materials composed of a multiple arrangement of nanosized
crystals in different orientations.
Their behavior depends upon shape, size and morphology – key
factors for performance and applications.
Ex. Fullerene, dispersed of nano particles, bundles of nanowires,
bundles of nanotubes, nanoballs, nanocoils etc.
Applications: Fullerene C60, C70, C540 important for ball
bearings to lubricate surfaces, drug delivery, vehicles and
electronic circuits.
2. They are important in catalysis, magnetic materials,
electrodes for batteries,

6. Graphene
Def: Graphene is a single layer of carbon atoms organized in
a hexagonal lattice.
Basic info:
1.Basic building block for other graphite materials.
2.2D material- length and width in nanoscale, third dimension
considered as zero.
3.Basic structural unit of graphite, charcoal, CNT’s, fullerenes.
Structure:
✓ All Carbon Sp2 hybridized. each C is attached to other
three carbon atoms to form hexagonal arranged networks
sheets of carbon atoms- huge and flat molecule with millions
of carbon atoms in the plane.
✓ Three hybrid orbital's take part in bonding and one
unhybridzed orbital having one electron at right angle to the
plane.

7. Structure:
✓Bond angle 120, Planar structure bond length 1.42
✓Hexagonal arranged network sheet like structure.
✓Distance between two sheets is 3.42 A & held together by weak
Van der Waals force of attraction in graphite.
✓Free electrons available.
✓Each sheet like molecule of graphite is called as Graphene.
✓ The graphite molecules can slide past over each other an
application of force & graphite is smooth (lubricating) material .
✓ Graphite molecule at high temperature can get folded to form
carbon nanotubes or decompose to form carbon molecules of
fullerenes.

8. Graphene sheets neatly stacked top of each other into a 3D
shape – Graphite

9. ✓Preparation of Graphene
The Most common techniques available for the production of
Graphene includes Micromechanical cleavage, chemical vapor
deposition, epitaxial growth on SiC substrates, chemical
reduction of Graphene oxide etc.
Properties of Graphene
The most promising Nanomaterials because of its unique
combination, thinnest but also strongest, better conductor of
heats, & electricity, optically transparent, Impermeable to gases.
Electronic Properties
It is one of the best electrical conductors on earth.
The unique atomic arrangement of the carbon atom in Graphene
allows its electrons to easily travel at extremely high velocity
without the significant chance of scattering, saving precious
energy typically lost in other conductors.

10. Mechanical Properties
The intrinsic mechanical property its stiffness, strength &
toughness Graphene stand out both as an individual material &
as a reinforcing agent in composites.
The stiffness of Graphene is vary good & the experimental
value of the second order elastic stiffness was equal to 380
Nm-1. This value corresponds to a young's modules of 1.1 Tpa,
assuming an effective thickness of 0.335nm.
Strength
Defect free, monolayer Graphene is considered to be the
strongest material ever tested with a strength of 42Nm-1 which
equates to an intrinsic of 130GPa.
Toughness
Fracture toughness, which is very relevant property to
engineering applications, is one of the most important
mechanical properties of Graphene & was measured as a
critical stress intensity factor of 4.0 +- 0.6 Mpa.

11. Applications of Graphene
1.Energy storage & Solar cells
Graphene is used to improve both energy capacity & charge
rate in rechargeable batteries, activated Graphene makes
superior super capacitors for energy storage, Graphene
electrodes used for making solar cell are inexpensive,
lightweight & flexible & multifunctional.
Graphene is useful for solar cells, super capacitors, Graphene
batteries, & catalysis for fuel cells. Graphene sheets has high
strength & toughness in all sheet directions for diverse
applications as Graphene based composite for vehicles,
optoelectronics & neural implants.
2.Photovoltaic devices
Due to their excellent electron transport properties & extremely
high carrier mobility, Graphene & other direct band gap
monolayer materials such as Transition-Metal Dichalcogenides
(TMDCs) used for low-cost flexible & highly efficient.

12. 3.Graphene Composites
It is the first ever Graphene infused carbon fiber helmet that
capitalizes on the materials thin strong & conductive, flexible &
light characteristics to create a helmet that absorbs & dissipates
impact better than your average helmet. It also disperses heat
more efficiently so its cooler.
Another example is the Graphene bike & bicycle. Enhancing
carbon fiber with Graphene allows to make lighter thinner tubes
that are stronger than regular carbon.
4.Sensors
Selective gas sensing with pristine Graphene, is also prepared.

13. Carbon Nanotubes……..
 CNT: Carbon nanotubes can be considered as cylinders
formed by rolling or folding of a graphite sheet mostly
closed at the ends with hemispherical fullerene..
 TWO types of CNT:
 Single walled carbon nanotubes (SWCNT):
 SWCNT is the single folding of thick layer graphite sheet
 SWCNT Three types
i) Zigzag ii) Armchair iii) Helical
 The zig zag and arm chair SWCNT are achiral while
helical SWCNT is chiral.
 The armchair SWCNT shows electrical conductivity
but zig zag and helical SWCNT are acts as
semiconductor.

14. 2. Multi walled carbon nanotubes (MWCNT)
Multi-walled nanotubes (MWNTs) consist
of multiple rolled layers (concentric tubes)
of graphene.

15. Chemical Vapour Deposition
 A hydrocarbon gas is cracked to produce carbon black.
 The presence of hexagonal rings in carbon black favors
CNT formation , if absent need of catalyst to produce CNT.
 SWCNT and MWCNT are obtained.
 Gas for cracking: Benzene Vapour, cyclohexane Vapour, CH4
 Pressure: 0.1 to 1 torr.
 Catalyst: Fe/Co/Ni/Pt
 Temperature: 1000 C

16. Properties………..
1.Mechanical properties:
✓ CNTs have exceptional mechanical stiffness and tensile
strength.
✓ CNTs are strongest and stiffest materials yet discovered
in terms of strength and elastic module (sp2 bonds).
2.They also show chemical stability, high electrical and
extraordinary thermal conductivity.
3.Optical properties: CNTs have useful absorption,
photoluminescence properties.
4.Electrical Conductivity:
✓ Semiconductor with Eg = 0-1eV.
✓ Made conducting by making its compounds with alkali
metals.

17. Applications of CNT………..
 Filtration- to separate particles of size greater than
diameter of CNT.
 To carry Stereospecific reactions.
 CNT as Nano cylinders for storing gas like hydrogen.
 Masks.
 Catalyst in some reactions.
 Coatings.
 Drug delivery System.
 Body part implants.
 Applications related to conductivity , in electronics.

18. Quantum Dots……..
 They are tiny semiconductor particles of a few
nanometers in size, having optical
and electronic properties that differ from larger
particles due to quantum effect.
 Typical dimensions 1 to 10nm
 QD are fluorescent Nanoparticles, when the quantum
dots are illuminated by UV light, can exhibit a range of
colors, depending upon their composition and size.
 An electron in the quantum dot excited to a state of
higher energy.
 In the case of a semiconducting quantum dot, this
process corresponds to the transition of an electron
from the valence band to the conductance band.

19.  The color of that light depends on the energy
difference between the conductance band and
the valence band.
 Nanoparticles of semiconducting materials such as
CdSe, GaAs, PbSe, PbTe etc are known as QD.
 Small nanosize change leads to QE, change energy
levels of their electrons and affects the optical and
electronic properties.
Shorter
wavelength
longer
wavelength

20. Properties of QD
1. Optoelectronic Properties:
✓Quantum dots have properties intermediate between
bulk semiconductors and discrete atoms or molecules.
✓Their optoelectronic properties change as a function of
both size and shape.
✓Larger QDs of 5–6 nm diameter emit
longer wavelengths, with colors such as orange or red.
✓Smaller QDs (2–3 nm) emit shorter wavelengths,
yielding colors like blue and green. However, the specific
colors vary depending on the exact composition of the
QD

21. 2. Optical properties (Fluorescence):
✓In semiconductors, light absorption generally leads to an
electron being excited from the valence to the conduction
band, leaving behind a hole.
✓The electron and the hole can bind to each other to form
an exciton. When this exciton recombines (i.e. the electron
resumes its ground state), the exciton's energy can be
emitted as light. This is called fluorescence.
✓In a simplified model, the energy of the emitted photon
can be understood as the sum of the band gap energy
between the highest occupied level and the lowest
unoccupied energy level, the confinement energies of the
hole and the excited electron and the bound energy of the
exciton (the electron-hole pair).

22. Fig: Band gap in quantum dots
As the confinement energy depends on the quantum
dot's size, both absorption onset and fluorescence
emission can be tuned by changing the size of the
quantum dot during its synthesis.
The larger the dot, the redder (lower energy) its
absorption onset and fluorescence spectrum.
Conversely, smaller dots absorb and emit bluer (higher
energy) light.

23. Quantum Dots Applications……..
A. In Electronics:
1.Have applications in thermoelectric, Solar cells and
fluorescent biological labels.
2.Quantum dot displays for more accurate colors.
3.Light emitting diodes are prepared by using quantum dots
such as QD-LED, QD-WLED displays.
B. In biology: Superior drugs and chemical transport,
Study of intracellular processes at the single molecule level,
high resolution cellular imaging, cell trafficking, tumor
targeting and diagnosis, antibacterial application.
C. Stability of fluorescent dyes:
QD coupled with OD to prepare dyes with 20 times brighter
and 100 times stable than traditional fluorescent dyes.

24. ANY
QUESTIONS…..

25. Thank You