Concepts of Nanotechnology -INTRODUCTION NANOTECHNOLOGY – definition WHAT IS SPECIAL IN NANO? NANOMATERIAL?? NANOMATERIAL SYNTHESIS NANOMATERIAL CHARACTERIZATION APPLICATIONS CONCLUSION

Mr. S. Gobalakrishnan M.Tech., (PhD)
Assistant Professor
Department of Nanotechnology
Noorul Islam University
Kumaracoil
INTRODUCTION
TO
NANOTECHNOLOGY
SYNTHESIS CHARACTERIZATION
Imaging

Introduction to Nanotech (Synthesis,Characterization)
CONTENTS
• INTRODUCTION
• NANOTECHNOLOGY – definition
• WHAT IS SPECIAL IN NANO?
• NANOMATERIAL??
• NANOMATERIAL SYNTHESIS
• NANOMATERIAL CHARACTERIZATION
• APPLICATIONS
• CONCLUSION

INTRODUCTION
NANO- Greek Word for “Dwarf”
A unit of measurement indicating one
billionth of meter.

INTRODUCTION
Size comparison
(1,000
–
10,000
nm
)
0.1 nm
~ 1nm
~
1
0
,
0
0
0
n
m
~ 75 – 100 nm
< 100 nm
~
5
–
5
0
n
m
~
2
n
m

NANOTECHNOLOGY- Definition
The measurement, prediction and construction of materials
on the scale of atoms and molecules.
Ability to
understand
control
manipulate
the matter
at the level of
atoms and molecules

NANOTECHNOLOGY
Is it new technology?
Mayas architecture – ancient Greek
8th
century
Damascus blades (AD 900 -AD 1800)
Transmitted Reflected
The Lycurgus Cup
( Romans -AD 300)
If yes, how much new it is? If no, how old it is?

NANOTECHNOLOGY
Science with mathematical relations
Field
Newtonian physics
Matter Wave physics
Diffraction Physics
Quantum mechanics
Nanoscience
Relation Description
F=ma Classical Mechanics
λ = h/p De-Broglie Relation
nλ = 2d sinθ Brags law
H ψ = Eψ Schrodinger
equation
Pi,q = f(lx, ly, lz)
Property “i” of
material “q” is a
function of three
dimensions

NANO DIMENSIONS
3D
BULK
2D
NANO
FILM
1D
NANO
WIRE
X>
100nm
Y
>
1
0
0
n
m
X
>
1
0
0
n
m
0D
QUANTUM
DOT
Z<100nm Z<100nm
Y<
100nm
X
Y
Z
< 100nm

REDUCED DIMENSIONS LEADS
When the size of the material decreases to nano region, the free
electrons begins to experience the effect of confinement, meaning that
their motion becomes limited by the physical size of the region.
Quantum Confinement
ELECTRONIC LEVEL (MICROSCOPIC)

REDUCED DIMENSIONS LEADS
Increase in Surface Area
MACROSCOPIC LEVEL
m2
150 (6x25) 750 (125x6x1) SURFACE (SA)
m3
125 (5x5x5) 125 (125x1x1x1) VOLUME (V)
1.2 6 SA/V

SIZE DEPENTENT PROPERTIES
Sugar Cubes In
Water
Sugar Granules In
Water
Solubility Of Sugar

• Surface to Volume ratio – All Materials
• Quantum confinement – Semiconductors (Change in band gap)
• Surface Plasmon resonance- Metals
• Super paramagnetism – Magnetic materials
• Drastic change in physical Properties of materials
– opaque to transparent - copper
– Inert to catalytic – platinum, gold (Structural change)
– Stable to combustible – Aluminum (reactivity)
– Insulator become conductor – silicon (SiO2) (tunneling)
– Decrease in Melting Temperature, increase in Solubility
(Increase in Surface atom)
SIZE DEPENTENT PROPERTIES

WHY NANOMATERIALS?
Batteries
Sun
Screen
In nanoscale science – WHAT CAN BE
DELIVERED?
 Fundamental understanding
 Novel techniques of synthesis
 Relationships
 Theoretical predictions
 Nanomaterials possess improved physical and chemical properties.
 Properties change with particle size, and can be controlled by
manipulating the building blocks.
 Functional nanomaterials, nanomaterials having essential functional
properties, - useful in processes such as adsorption, ion-conducting,
separation, catalysis, biomaterials and biosensing, not in structural
and electronic applications.
In nanomaterials development
 Low cost and high rate production of nanoparticles
 Tailor-designed carbon nanotubes
 Novel biomaterials (orthopedic, tissue repair)
 Highly effective and long lasting catalysts and
nanocomposites for energy applications

BUILDING BLOCKS
1. Nanotubes
2. Nanorods
3. Nanowires
4. Nanocrystals
5. Nanoshells
6. Nanoclusters
7. Nanoflakes
8. Nanofibers
9. Nanofilms
10. Nanocombs
11. Nanowires
12. Nanorings
13. Nanobots
14. NanoCapsules
15. Dendrimers ………!
• Micelles
• Fullerenes
• Quantum dots
• Nanocrystals
• Dendrimers
• Liposomes
• Nanowires
• Nanotubes
• Block copolymer
Nanomaterials as building blocks for all kinds of technologies
from quantum computing to opto-electronics.

NANOMATERIALS & NANOSTRUCTURES
Nanostructures of ZnO synthesized
UNDER CONTROLLED CONDITIONS by
THERMAL EVAPORATION of solid
powders
* J.S. Murday, AMPTIAC Newsletter 6 (2002) (1), p. 5.
FIELD PROPERTY SCALE LENGTH
Electronics Electronic wavelength 10–100 nm
Inelastic mean free path 1–100 nm
Tunneling 1–10 nm
Magnetics Domain wall 10–100 nm
Spin-flip scattering length 1–100 nm
Optics Quantum well 1–100 nm
Eva.Wave decay length 10–100 nm
Metallic skin depth 10–100 nm
Superconductivity Cooper pair coherence 0.1–100 nm
Meisner penetration depth 1–100 nm
Mechanics Dislocation interaction 1–1000 nm
Grain boundaries 1–10 nm
Crack tip radii 1–100 nm
Nucleation/growth defect 0.1–10 nm
Surface corrugation 1–10 nm
Catalysis Surface topology 1–10 nm
Supramolecules Kuhn length 1–100 nm
Secondary structure 1–10 nm
Tertiary structure 10–1000 nm
Immunology Molecular recognition 1–10 nm
Characteristic lengths in
solid-state science
model*

• ………….…to reach $10 Billion by 2012.
• USA largest regional market US$1.12 billion revenues in 2008,
• Western Europe is the 2nd largest regional market accounting for over 30% of
global revenues.
• Asia-Pacific is projected to be the fastest growing market, with revenues poised to
increase at a compounded annual rate of 38.7% over the analysis period 2002-
2015.
• Worldwide NanoMaterial oxide revenues are forecast to reach US$6 billion in
2013. Revenues for nano-metals are projected to approach US$3 billion by 2015.
1. Nanomaterials of all types are poised to register robust growth driven by growing
interest.
2. Emerging NanoMaterials SWCNTs, Dendrimers - is another billion-dollar segment
expected to post double-digit growth through 2015.
3. Oxides and metals are expected to capture a major share of global NanoMaterial
revenues in the short-term.
4. Electronics is the largest end-use market for NanoMaterials while healthcare is the
most promising and dominate worldwide revenues.
5. But, commercial usage of NanoMaterials is limited to few applications such as
sunscreen lotions, wafer polishing, and treatment of textiles.
GLOBAL NANOMATERIALS MARKET 2012

Au & Ag
18
Increasing aspect ratio
1
Gold nanoparticles with increasing aspect ratio
Semiconductor Nanoparticles
Quantum dots are semiconductors
particles that has all three dimensions
confined to the 1-100 nm length scale
Colloidal CdSe Quantum Dots dispersed in hexane
Matter has unusual properties on the nm scale
4 nm 12 nm 25 nm 37 nm
Au NP’s
With
diffused
light
With
focuse
d light

NANOMEDICINE
Nature Nanotechnology | VOL 2 | AUGUST 2007 | www.nature.com/naturenanotechnology
• Magnetic-field guided drug delivery (MDD) with
magnetic aerosols.
• Super paramagnetic nanoparticles are placed in
microdroplet aerosols (green) and delivered along
the airways (brown) toward the lungs (grey).
• A localized magnetic field causes large numbers of
nanoparticles to accumulate in a specific region,
shown here in red.
Super
paramagneti
c
Nanoparticle
s
γ – Fe2O3 Colloidal Ag modified γ – Fe2O3

MAGNETIC NANOPARTICLES
 The ability to carry one or more
therapeutic agents;
 biomolecular targeting through one
or more conjugated antibodies or
other recognition agents;
 imaging signal amplification, by way
of co-encapsulated contrast agents;
and
 bio-barrier avoidance, exemplified by
an endothelial tight-junction opening
permeation enhancer, and
 by polyethylene glycol (PEG) for the
avoidance of macrophage uptake by
macrophages.
Nature Reviews Cancer 5, 161-171 (2005); CANCER NANOTECHNOLOGY:
OPPORTUNITIES AND CHALLENGES

21
MEMS & NEMS
SEM of a silicon RESONANT NANOSTRUCTURE operated in air.
(1st Nanostructure to be operated in air)
L. SEKARIC et al, Nature, 30 Sep 2002; Applied Physics Letters 81, 2641–2643, 2002
Source: Oak Ridge National Labs
MEDICAL TELESENSOR
CHIP on a fingertip can
measure and transmit
body temperature
MICROCANTILEVER
SENSOR
Human Hair
1
MEMS & NEMS are a great promise for chemical- and mass-sensing applications
Optical Bench
>1m

SENSORS
TINY HEART – Heart of the
smart Sensor
http://www.anl.gov/OPA/
logos20-3/smartsensor01.htm
Finger Tip Sensors
http://www.emt.uni-linz.ac.at/
education/diplomarbeiten/
da_kornsteiner/kornsteiner.html
A Bee Tracker

NANO METAMATERIALS
• A METAMATERIAL is a material which gains its
properties from its structure rather than directly from
its composition.
• METAMATERIALS can be distinguished from other
composite materials, the metamaterial label is usually
used for a material which has unusual properties.

SYNTHESIS OF NANOMATERIAL
Homogenous
Narrow particle size distribution
High surface area
High Pure
Improved properties
Nanosize particles
Preferable characteristics…

SYNTHESIS OF NANOMATERIAL
SOLUTION
CHEMISTRY
PHYSICAL
VAPOUR
DEPOSITION
CHEMICAL
VAPOUR
DEPOSITION
BOTTOM UP TOP TOWN
CRUSHING/
BREAKING
Nanomaterial

Sol- Gel
1. Hydrolysis
2. Condensation
3. Gelation
4. Ageing
5. Drying
6. Densification
The evolution of inorganic networks through the formation of a
colloidal suspension (sol) and gelation of the sol to form a
network in a continuous liquid phase (gel).
Removal of the liquid from the sol yields the gel, and the sol/gel transition
controls the particle size and shape.
Calcination of the gel produces the oxide

Sol- Gel
Process…
Step 1: Formation of different stable solutions of
the metal precursor (the sol).
Step 2: Gelation resulting from the formation of an oxide- or
alcohol- bridged network (the gel)
By a polycondensation or polyesterification reaction
M OR + H OH MOH +
→ ROH (hydrolysis)
MO H + RO M → M-O-M + ROH (condensation

Sol- Gel
Process…
Step 3: Aging of the gel (Syneresis), during which the
polycondensation reactions continue until
the gel transforms into a solid mass. (7 days)
Step 4: Drying of the gel, when water and other volatile
liquids are removed from the gel network.
Step 5: Dehydration, during which surface- bound M-OH groups
are removed (stabilizing the gel against rehydration. (8000
C)
Step 6: Densification and decomposition of the gels
at high temperatures (T>8000
C).

Sol- Gel
Process…
Metal Alkoxide
Solutions
Sol
Hydrolysis
Polymerization
Dense film
Heat
Ceramic Fibers
Furnace
Spinning
Xerogel Film
Coating
Wet Gel
G
e
l
l
i
n
g
Particles
P
r
e
c
i
p
i
t
a
t
i
o
n
Xerogel
Evaporation
Aerogel
Extraction of
Solvents
Dense Ceramics
Heat

Sol- Gel
Advantages…
• An efficient and cost-effective
• To produce nanocrystalline elemental, alloy, and
composite
• Any combination of materials at very low
temperatures
• Greater control of material chemistry and
homogeneity
• Sol–gel synthesized powders could be processed,
such as for coating, carburization, and nitridation

PHYSICAL VAPOUR DEPOSITION
PVD is fundamentally a vaporization coating technique,
involving transfer of material on an atomic level
The process involved four
steps:
• Evaporation
• Transportation
• Reaction
• Deposition
PVD processes are carried out under vacuum conditions.
Simple Set-up
Vacuum system Sample
Substrate

process involved…..
A target, consisting of the material to be deposited is bombarded by
a high energy source such as a beam of electrons or ions
Evaporation
+
Plasma
+
Energy > 100eV

The movement of ‘vaporized’ atoms from the target to the substrate to
be coated and will generally be a straight line affair.
Transportation

Some cases coatings will consist of metal oxides, nitrides, carbides and
other such materials.
In these cases, the target will consist of the metal. The atoms of metal
will then react with the appropriate gas during the transport stage
Reaction
TiO2
TI
O O

CHEMICAL VAPOUR DEPOSITION
CVD - Precursors are Gases
Chemical vapour deposition or CVD is a generic name for a
group of processes that involve depositing a solid material from a
gaseous phase
PVD - Precursors are solid
(Material to be deposited being vaporized from a solid target
and deposited onto the substrate)

Chamber
(Quartz Tube)
Vacuum System
Furnace
(Heating Coil)
S
u
b
s
t
r
a
t
e
SET UP
Gas Cylinders
A
i
r
F
l
o
w
C
o
n
t
r
o
l
l
e
r

Gas delivery system – For the supply of precursors to the chamber
Reactor chamber – Chamber within which deposition takes place
Energy source – Provide the energy/heat that is required to get
the precursors to react/decompose.
Vacuum system – A system for removal of all other gaseous species
Exhaust system – System for removal of volatile by-products from
the reaction chamber.
Process control equipment – Gauges, controllers etc. to
monitor process parameters such as
pressure, temperature and time.
Basic Components

1. Precursor gases (often diluted in carrier gases) are
delivered into the reaction chamber at approximately
ambient temperatures.
3. The substrate temperature is critical and can influence
what reactions will take place.
2. As they pass over or come into contact with a heated
substrate, they react or decompose forming a solid
phase which and are deposited onto the substrate.
Process

Precursors…..
Thus precursors for CVD processes must be volatile,
but at the same time stable enough to be able to be delivered
to the reactor.
• Halides - TiCl4, TaCl5, WF6, etc.
• Hydrides - SiH4, GeH4, AlH3(NMe3)2, NH3,
etc.
• Metal Alkoxides - Ti(OiPr)4, etc.
• Metal Carbonyls - Ni(CO)4, etc.

Imaging Techniques
SOURCE
Coulomb, van Der
Waals forces
Light Electron
Optical
Microscopes
Electron
Microscopes
X-Ray
X-Ray
Diffraction
Atomic Force
Microscopes
Morphology,
Ordering in
liquid Crystals
Crystallographic
Information,
Element Analysis
Morphology,
Crystal Structure,
Composition,
Core Shells
structures,..etc
Topography,
Surface Roughness,
Alloy Composition,
Atomic
Manipulation,..etc
(SEM, TEM) (AFM)

MICROSCOPY (light)
The objective, is to observe features that are beyond
the resolution of the human eye (≈100 µm)
Reflected or transmitted light from the
sample enters the eye after passing through
a magnification column
Condenser
Objective
Projection
S
p
e
c
i
m
e
n

MICROSCOPY (light)
Resolution…
The theoretical limit
The ability of an imaging system to resolve detail in the object
The wavelength of light used,
The numerical aperture of the system
r =
λ is wave length of light
NA Numerical Aperture of system
White light
0.55 µm
Theoretical limit of
resolving power is
currently about 0.2 µm

MICROSCOPY (light)
Resolution…
The numerical aperture,
• A measure of the light gathering ability of the objective,
or
• light-providing ability of the condenser
NA = n sin
Where
n is the refractive index of the medium between the cover
glass and the objective front lens,
AA is the angular aperture of the objective

MICROSCOPY (electron)
Resolution, r =
Wave length of electron
λ = = =
• 10 kV SEM is then 0.12 x 10−10
m (0.12 Å)
• 200 kV TEM is 0.025x10−10
m (0.025 Å)
• Usually in X-RD is in the order of 1x10−10
m
(Cu-k : =1.54
α λ Å).
White light
0.55 µm
or
5500 Å

ELECTRON MICROSCOPY
• The Scanning Electron Microscope (SEM).
• The Transmission Electron Microscope (TEM).
Single technique to gain insights into structure, topology,
morphology, and composition of a material

Introduction to Nanotech (Syn
thesis,Characterization)
Back Scattered electrons
Auger
electrons
Secondary
electrons
Incident
electrons
Direct Beam
Elastically Scattered
electrons Inelastic Scattered
electrons
The different types of electron scattering
Specimen
X-Rays
EDXS
Electron Vs Matter

As the electrons penetrate the surface, a number of interactions
occur
Signal….
Electron Vs Matter
Energy transferred to specimen
(X-rays, Auger or secondary
electrons, plasmons, phonons, etc.)
Scattering
Elastic
In-Elastic
No energy loss
(Direct Beam) Eel = E0
Eel < E0

Electron Vs Matter
Elastic Scattering
Back scattered
Electron
scattered Electrons
Nucleus
(Positive)
Electron
Cloud
(Negative)
Eel = E0
Electrostatic
or
Coulombic interaction
Its path is deflected
towards the core as a
result
F = Q1Q2 / 4π o r
ε 2
“F” increase with Atomic
Number “Z”
r

Electron Vs Matter
Eel < E0
In-Elastic Scattering
Part of the energy (electron carries) is transferred to the specimen
• Inner Shell ionization
• Secondary electrons
• Auger Electrons
• X-rays
• Phonons
An extremely surface sensitive since
Auger electrons have short mean
free paths in solids

Secondary e-
s
Scattered e-
s
Electron Vs Matter
In-Elastic Eel < E0
K
L1
L2
L3
X Rays
Elow
Ehigh
∆E = Ehigh – Elow
∆E = h ν
∆E = h ν

Electron Vs Matter
Secondary electrons
(Below 50 eV)
Valence or conduction band e-
s need small amount
of energy to overcome the work function
Forming Images Of Morphology And Surface
Topography

Auger e-
s
Secondary e-
s
Scattered e-
s
Electron Vs Matter
In-Elastic Eel < E0
K
L1
L2
L3
Elow
Ehigh
∆E = Ehigh – Elow
∆E = h ν
∆E = h ν

SCANNING ELECTRON MICROSCOPE

A source of electrons is focused (in vacuum) into a fine probe
that is rastered (the beam sweeps horizontally left-to-right at a
steady rate) over the surface of the specimen.
Screen
Sample
Deflection
Coil
Electron Gun
Deflection
Amplifier
Detector
Signal

Commercial Scanning Electron Microscope (SEM)
Magnification
10,000 -
5,00,000 X
Energy
0.5 keV to 40 keV
Resolution
1µ - 2nm

Graphene 20x20 (microns) Grating(microns)
Red Ant (Full)
Gold NPs
Red Ant (Head)
Red Ant (Head with neck)
200 µm
Images

TRANSMISSION ELECTRON MICROSCOPE
Commercial Transmission Electron Microscopes (SEM)
Magnification
7,50,000 X
Energy
About 200keV
Resolution
0.2nm-0.5nm

Graphene Sheet
Images
Gold NPs(2X2 nm2
)
Silica coated on Gold
(2X2 nm2
)
CdS (2X2 nm2
) Gold (2X2 nm2
)

ATOMIC FORCE MICROSCOPE
AFM provides a 3D profile of the surface on a Nanoscale, by
measuring forces between a sharp probe (<10 nm) and
surface at very short distance (0.2-10 nm probe-sample
separation).
The probe is supported on a flexible cantilever. The AFM tip
“gently” touches the surface and records the small force
between the probe and the surface
F = - kX
F – Force (10-9
N – 10-6
N)
k – Spring Constant (0.1-1 N/m)
X – Cantilever deflection
Mode
x<0.5 nm Contact
0.5nm<x<2nm Non Contact
0.1nm<x<10nm Tapping

• Probes (Cantilever & Tips)
• Optical detection system,
• Piezo-scanners and
• Electronics for a management of scanning procedures and
data acquisition
In the microscope, these components are assembled into a
microscope stage, which must satisfy the requirements of
minimum vibrational, acoustic and electronic noise as well as
small thermal drift.
Basic Components

Cantilever

Optical Alignment
Photo
detector
Laser Source
Tip
Cantilever
Z Scanner
Stage (X, Y Scanner)
Sample
Feedback
Loop

Optical
Microscopy Set UP
Commercial Atomic Force Microscopes
Cantilever and Laser optics
Stage (X, Y Scanner)

Attractive Force (non-contact)
At large probe-sample distances, the
forces are attractive
Repulsive (contact)
At short probe-sample distances,
the forces are repulsive
The force is detected by the deflection of a spring, usually a cantilever

Distance
(From Sample to Tip)
x
x
Contact Non-Contact
Tapping
Force
Repulsive
Attractive
Force – Distance Curve

Tip
Tip Path
Surface
Tip
Tip Path
Surface
High Aspect Ratio Tip
Low Aspect Ratio Tip

Graphene (2X2 nm2
)
Gold (500X500 nm2
)
Surface of Hard Disc (10X10 µm2
)
Images

Concepts of Nanotechnology -INTRODUCTION NANOTECHNOLOGY – definition WHAT IS SPECIAL IN NANO? NANOMATERIAL?? NANOMATERIAL SYNTHESIS NANOMATERIAL CHARACTERIZATION APPLICATIONS CONCLUSION

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