Smart Materials & Devices
Dr. Pramod Kumar Singh
Department of Physics
School of Basic Sciences & Research
Sharda University, Greater Noida
Email: pramodkumar.singh@sharda.ac.in
Syllabus
7.01
SMDXXX.A
Unit A
Materials- Basic Concepts
7.02
SMDXXX.A1
Unit A Topic 1
Classification of Materials, Bonding in solids
7.03
SMDXXX.A2
Unit A Topic 2
Crystal structure, Bravais lattice, Miller Indices
7.04
SMDXXX.A3
Unit A Topic 3
Imperfections of crystals
7.05
SMDXXX.B
Unit B
Dielectrics, Superconductors and Magnetic Materials
7.06
SMDXXX.B1
Unit B Topic 1
Dielectic materials and their properties
7.07
SMDXXX.B2
Unit B Topic 2
Superconductors and their applications
7.08
SMDXXX.B3
Unit B Topic 3
Magnetic materials and their properties
Syllabus
7.09
SMDXXX.C
Unit C
Composite & Nanocomposite materials
7.10
SMDXXX.C1
Unit C Topic 1
Introduction of composite and Nanocomposite materials
7.11
SMDXXX.C2
Unit C Topic 2
Metal-Ceramic nanocomposite
7.12
SMDXXX.C3
Unit C Topic 3
Polymer based nanocomposites
7.13
SMDXXX.D
Unit D
Characterization Techniques
7.14
SMDXXX.D1
Unit D Topic 1
X-ray diffraction
7.15
SMDXXX.D2
Unit D Topic 2
UV-Visible spectroscopy
7.16
SMDXXX.D3
Unit D Topic 3
Infrared spectroscopy
7.17
SMDXXX.E
Unit E
Devices
7.18
SMDXXX.E1
Unit E Topic 1
Devices for energy conversion
7.19
SMDXXX.E2
Unit E Topic 2
Storage Devices
7.20
NSTXXX.E3
Unit E Topic 3
Sensors and Microelectronic devices
References
9
References
1. Material Science and Engineering An Introduction by: William D. Callister
9.1
Text book
2. Nanocomposite Science and Technology, P. M. Ajayan, L. S. Schadler, P. V. Braun
3. Chemistry of nanomaterials: Synthesis, properties and applications by CNR Rao (Taylor & Francis 2008)
9.2
Other references
4.Structure and Properties of Engg. Materials by: V R S Murthy, A K Jena
SMART MATERIALS
SMART Materials are special solids which
can be tailored to develop desired
properties applied for fabrication of devices
leading to societal benefits
Materials Engineering
Materials, Materials Science and Materials Scientist play a
very vital role in the development of a country
Properties of materials are size dependent
Materials scientist claim that 21st century is the century of
materials and especially nanomaterials/smart materials
SMARTCOMPOSITES
Properties of materials are size dependent
COMPOSITE/NANOCOMPOSITES
COMPOSITE/NANOCOMPOSITES
Fundamentals of Materials Science and Engineering, William D. Callister, Jr.
Atlantis Space Shuttle Orbiter, USA
Fundamentals of Materials Science and Engineering, William D. Callister, Jr.
Fundamentals of Materials Science and Engineering, William D. Callister, Jr.
CLASSIFICATION OF MATERIALS
Solid materials have conveniently been grouped into
three classes
1.Metals
2.Ceramics
3.Polymers
Combination of above materials give variety of other
materials
Now most of the new materials come under the category of
Smart Materials or Future Materials
THREE MAJOR ENGINEERING MATERIALS
*Modern technologies require materials with unusual
combinations of properties that can not be met by the
conventional metal alloys, ceramics and polymeric
materials.
This is usually true for materials that are needed for
aerospace, underwater, and transportation applications.
For example aircraft engineers are increasingly searching
for structural materials that have low densities, are strong,
stiff and abrasion and impact resistant, and are not easily
corroded.
This is a formidable combination of characteristics.
Frequently strong materials are relatively dense; also,
increasing the strength or stiffness generally results in a
decrease in impact resistance.
Atlantis Space Shuttle Orbiter, USA
Fundamentals of Materials Science and Engineering, William D. Callister, Jr.
Fundamentals of Materials Science and Engineering, William D. Callister, Jr.
Composites
Composite is considered to be any multiphase material that
exhibits a significant proportion of the properties of both
constituents such that a better combination of properties is
realized.
*Better property combinations are fashioned by the judicious
combination of two or more distinct materials
Composites
*In addition, the constituent phases must be chemically
dissimilar and separated by a distinct interface.
Thus most metallic alloys and many ceramics do not fit this
definition because their multiple phases are formed as a
consequence of natural phenomena.
Composites
• Composites are a combination of two or more organic or inorganic
components one of which serves as a matrix holding the materials
together and then other of which serves as reinforcement in the form
of fibers
• Two inherently different materials that when combined together
produce a material with properties that exceed the constituent
materials.
• Composites are lightweight and strong but they are complex to
manufacture, expensive and hard to inspect for flaws
Composites
Many composite materials are composed of just two
phases; one is termed the matrix, which is continuous
and surrounds the other phase, often called dispersed
phase.
The properties of composites are a function of the
properties of the constituent phases, their relative
amounts and the geometry of the dispersed phase.
Composites
Composites often have only two phases
• Matrix phase
– continuous - surrounds other phase
• Dispersed phase
– discontinuous phase
Matrix (light)
Dispersed phase (dark)
Classification of Artificial
Composites
Composites
Particulate
Fiber
Large
Dispersion
Particle Strengthened
Continuous
Structural
Laminates
Discontinuous
Aligned
Random
Sandwich
Panels
Properties of Composites
Properties depend on:
4constituent phases
4relative amounts
4geometry of dispersed phase
4shape of particles
4particle size
4particle distribution
4particle orientation
Parameters on which properties depend
Concentration
Distribution
Shape
Orientation
Size
Composites Offer
High Strength
Light Weight
Design Flexibility
Consolidation of Parts
Net Shape Manufacturing
Biocomposites
• Biocomposites combine plant fibers with resins to create natural based
composite materials.
• High tensile plant fibers including, kenaf, industrial hemp, and flax, can
be combined with traditional resins to create an alternative to
traditionally steel or fiberglass applications.
• Some advantages over traditional composites:
– Reduced weight
– Increased flexibility
– Greater moldability
– Less expensive
– Sound insulation
– Renewable resource
– Self-healing properties
NANOCOMPOSITES
A nanocomposite is as a multiphase solid material
where one of the phases has one, two or three
dimensions of less than 100 nanometers (nm),
OR
structures having nano-scale repeat distances
between the different phases that make up the
material.
NANOCOMPOSITES
Constituents have at least one dimension in the
nanometer scale.
– Nanoparticles (Three nano-scale dimensions)
– Nanofibers (Two nano-scale dimensions)
– Nanoclays (One nano-scale dimensions)
Properties of Nanocomposites
• Tiny particels with very high aspect ratio, and hence
larger surface area.
• Larger surface area enables better adhesion with the
matrix/surface.
• Improvement in the mechanical performance of the
parent material.
• Better transparency due to small size(>wavelength
of light).
Why Nanocomposites?  Multi-functionality
• Small filler size:
– High surface to volume ratio
• Small distance between fillers  bulk interfacial material
– Mechanical Properties
• Increased ductility with no decrease of strength,
• Scratching resistance
– Optical properties
• Light transmission characteristics particle size dependent
nanocomposite
Stress
Traditional
polymer
Strain
Scratch Resistant, Transparent, Filtering Coatings
Visible
Ultraviolet
TEM of the 16.7wt% nano
alumina filled gelatin film
Transmittance rate of 16.7wt.% nanoalumina filled
gelatin films coated on 0.1mm thick plastic substrate
Size limits for these effects have been proposed
<
5 nm for catalytic activity
<
20 nm for making a hard magnetic material soft
<
50 nm for refractive index changes
<
100 nm for achieving superparamagnetism,
mechanical strengthening.
Nanoclays
• Silicates layers separated by an
interlayer or gallery.
• Silicates layers are ~ 1 nm thick, 300
nm to microns laterally.
• Polymers as interlayers.
• Tailor structural, optical properties
Nanofibers - Nanotubes
~1000 GPa (SWCNT)
~1200 GPa (MWCNT)
Tensile Strength ~ 100 GPa
•
Nanotubes in metal, metal oxide
and ceramic matrix have also
been fabricated.
•
Nanotubes in polymer matrices
by mixing, then curing.
•
Most important filler category in
nanocpomposites
Modulus
Thermal
Conductivity
Density
2000 W/m/K
Length
up to microns
1300 –1400 kg/cm3
Nanocomposite VS Composite
In mechanical terms, nanocomposites differ from conventional
composite materials
*Exceptionally high surface to volume ratio of the reinforcing
phase and/or its exceptionally high aspect ratio.
The reinforcing material can be made up of particles (e.g.
minerals), sheets (e.g. exfoliated clay stacks) or fibres (e.g.
carbon nanotubes or electrospun fibres).
The area of the interface between the matrix and reinforcement
phase(s) is typically an order of magnitude greater than for
conventional composite materials.
Nano composites are found in nature also. It is found in
abalone (small or very large-sized edible sea snail) and
bones.
Advantage of using the nanocomposites:
• Greater tensile /flexural strength
• Reduced weight for the same performance
• Flame retardant properties
• Improved mechanical strength
• Higher electrical conductivity
• Higher chemical resistance
A simple example of a normal composite can be considered – we
do have concrete for our houses. What exactly is this concrete?
It’s a blend of cement, sand, and metal rod. These composition
changes the total property of the material used. It becomes so
hard that it can withstand tonnes of weight equally. It’s from this
concept we device the idea about the nanocomposites.
Nanocomposite as a Multiscale System
– Macroscale composite structures
– Clustering of nanoparticles - micron scale
– Interface - affected zones - several to tens
of nanometers - gradient of properties
1.5
diffusion/bulk diffusion
R
g
unbonded
bonded
1
0.5
0
1
2
3
4
5
distance from the particle
– Polymer chain immobilization at
particle surface is controlled by
electronic and atomic level structure
This large amount of reinforcement surface area means that a relatively
small amount of nanoscale reinforcement can have an observable effect
on the macroscale properties of the composite. For example, adding
carbon nanotubes improves the electricaland thermal conductivity.
Other kinds of nanoparticulates may result in enhanced optical properties,
dielectric properties, heat resistance or mechanical properties such as
stiffness, strengthand resistance to wear and damage.
In general, the nano reinforcement is dispersed into the matrix during
processing. The percentage by weight (called mass fraction) of the
nanoparticulates introduced can remain very low (on the order of 0.5% to
5%) due to the low filler percolation threshold, especially for the most
commonly used non-spherical, high aspect ratio fillers (e.g. nanometer-thin
platelets, such as clays, or nanometer-diameter cylinders, such as carbon
nanotubes).
Synthesis of Nanocomposites
• Others –
•
Chemical Synthesis:
1.
Gas Phase Synthesis
Chemical Vapor Condensation
Combustion Flame Synthesis
Liquid Phase Synthesis
2.
3.
4.
• Mechanical Deformation
• Thermal recrystallization
Gas Phase Synthesis
(Synthesis of ultra pure metal powders and compounds of metal oxides(ceramics) )
•
•
•
•
•
The nano powder formed normally has the same
composition as the starting material.
The starting material, which may be a metallic or
inorganic material is vaporized using some source of
energy
The metal atoms that boil off from the source quickly
loose their energy. These clusters of atoms grow by
adding atoms from the gas phase and by coalescence
A cold finger is a cylindrical device cooled by liquid
nitrogen. The nano particles collect on the cold finger
The cluster size depends on the particle residence time
and is also influenced by the gas pressure, the kind of
inert gas, i.e. He, Ar or Kr and on the evaporation rate of
the starting material. The size of the nano particle
increases with increasing gas pressure, vapor pressure
and mass of the inert gas used.
Chemical Vapor Condensation
•
the precursor vapor is passed through a hot walled reactor. The
precursor decomposes and nano particles nucleate in the gas phase.
The nano particles are carried by the gas stream and collected on a
cold finger. The size of the nano particles is determined by the
particle residence time, temperature of the chamber, precursor
composition and pressure.
Nanocomposites
Combustion Flame Synthesis
•
•
Energy to decompose the precursor may be supplied by burning a fuel-air mixture
with the precursor. In order to reduce agglomeration of the particles in the flame,
the flame is specially designed to be low pressure.
If you have observed the flame of a candle, you would have noticed that the flame
consist of a blue center and a yellow to red periphery. This is because the
temperature in the flame varies with position in the flame. Such a variation in the
temperature profile of the flame would cause nanoparticles of different sizes to
grow in the different regions of the flame. This is avoided by designing the flame
to have a 'flat temperature profile' i.e. a constant temperature across its width.
Liquid Phase Synthesis
•
•
Two chemicals are chosen such that they
react to produce the material we desire
An emulsion is made by mixing a small
volume of water in a large volume of the
organic phase. A surfactant is added. The
size of the water droplets are directly related
to the ratio of water to surfactant. The
surfactant collects at the interface between
the water and the organic phase. If more
surfactant were to be added, smaller drops
would be produced and therefore, as will
become apparent, smaller nano-particles.
The progress in nano composites is varied and covers many industries.
Nano Composites can be made with a variety of enhanced physical,
thermal and other unique properties.
They have properties that are superior to conventional micro scale
composites synthesized using simple and inexpensive techniques.
Materials are needed to meet a wide range of energy efficient applications
with light weight, high mechanical strength, unique color, electrical
properties and high reliability in extreme environments.
Applications could be diverse as biological implant materials, electronic
packages and automotive or aircraft components. Although some of the
properties will be common between the applications, others will be quite
different.
An electronic package polymer composite must be electrically insulating,
while an aircraft component may need to be electrically conductive to
dissipate charge from lighting strikes.
The additions of small amounts of nano particles to polymers have been
able to enable new properties for the composite material, but results are
highly dependent on the surface treatment of the nano particles and
processing used.
It is important to determine whether nano materials could be integrated
into nano composite to enable multiple desirable properties for a given
application.
While industry is seeking materials to meet challenges with unique
properties, there are no “rule of mixtures” to identify how to mix multiple
nano materials in a composite structure and all required properties nano
materials often have unique properties that could enable composite
materials with multiple unique properties simultaneously; however, it is
often challenging to achieve these properties in large scale nano
composite materials.
Furthermore, it is important that nano materials have desirable properties
that can’t be achieved through use of conventional chemicals and
materials.
To access the positional value of nano materials, it is important to
determine which nano materials can be effectively integrated into nano
composites and what new or improved properties this enables.
Then it will be important to determine the effectiveness of dispersion
of the nano particles in the matrix and how this affects the structure
of the polymer to enable optimization of the desired property.
Once the basic models of this are developed, it will be resulting
structure and properties of the nano composite.
One nano composite may be required to improve the mechanical
property, ad another may be required to change the electrical
properties; however the addition of electrical material may also
change the mechanical properties of the nano composite trough
interactions with the polymer and nano particles.
Thus, models of the interactions within the nano composite are
needed to enable development of effective rules of mixtures.
This may require a combination of numerical modeling,
characterization and informatics to enable this nano composite with
properties by design capability.
As this capability is developed, it will be important to characterize the
interactions of the nano particles with environmental effects including
moisture, temperature and stress to assess potentional degradation of the
nano composite’s properties through its life.
Thus, the nano composite must have multiple new and unique properties for
a specific application, but those properties must not degrade significantly
through the life of the material.
Developing these capabilities will require significant research into
interactions of the nano materials in the polymer matrix and how these are
changed with temperature, moisture and mechanical stress.
In general, two idealized polymer layered nano composite structures are
possible; intercalated and exfoliated. The greatest property enhancements
are generally observed for exfoliated nano composites. These consist of
individual nano meter filler layers suspended in a polymer matrix. In
contrast, intercalated hybrids consist of well ordered multilayer’s with
alternating polymer / nano mater filter layers with a repeat distance of a new
nano meters. In reality many systems fall short of the idealized exfoliated
morphology.
Engineering Properties of Materials
The mechanical, electrical, thermal, optical, electrochemical, catalytic
properties of the nanocomposite will differ markedly from that of the
component materials.
• Normal stress is the state leading to expansion or contraction. The formula
for computing normal stress is:
P
s
A
P
L
P
DL
A
Where, s is the stress, P is the applied force; and A is the cross-sectional area.
The units of stress are Newtons per square meter (N/m2 or Pascal, Pa).
Tension is positive and compression is negative.
• Normal strain is related to the deformation of a body under stress. The
normal strain, e, is defined as the change in length of a line, DL, over it’s
original length, L.
DL
e
L
Young's modulus of elasticity (E) is a measure of the stiffness of the
material. It is defined as the slope of the linear portion of the normal
stress-strain curve of a tensile test conducted on a sample of the
material.
Yield strength, sy, and ultimate strength, su, are points shown on
the stress-strain curve below.
Stress, s
su
Rupture
sy
s
E
1
•
Strain, e
For uniaxial loading (e.g., tension in one direction only): s = E e
s
• Shear stress, t, is the state leading to distortion of the material (i.e., the
90o angle changes). The corresponding change in angle, in Radians, is
called shear strain, g. The slope of the linear portion of the t-g is called
shear modulus of elasticity, G.
Stress, t
G
1
Strain, g
54
• Poisson’s ratio, n, is another property defined by the negative
of the ratio of transverse strain, e2, over the longitudinal
strain, e1, due to stress in the longitudical direction, s1.
12  
2
e2
e1
Original shape
1
s1
s1
e
2
e
1
55
• Anisotropic materials have different properties in different
directions. In the most general case, they are defined by 21
independent constants. Special cases include:
– Orthotropic: wood and some composites
– Transversely isotropic: some continuous fiber reinforced composites
Fibers
56
A group of Chinese researchers prepared dye synthesized solar using micro /
nano composite TiO2 porous films.
Bloo solar is developing and manufacturing revolutionary nano structured
ultra thin film solar PV products that will provide affordable clean renewable
energy for everyone.
In addition to a large potential impact on solar energy production, nano
composites also have an impact on nuclear energy.
Nano composites also can save energy when incorporated into paints; TAG
technology has developed a nano particle that when added to paint only
allows heat flow in one direction.
Other industries are also influenced by nano composites, including
computers, electronic magnetic, industrial components, water
remediation and medical devices.
Nano composite permanent magnet materials are a new type of
permanent magnet material consisting of magnetically hard and soft
grains, both in nano meter size.
Those materials have a high potential to be developed into high
performance permanent magnets with very high energy product.
The new magnets will have lower cost, high magnetic performance,
and better corrosion resistance as a result of the significantly
reduced rare earth content.
The new magnets will also have improved fracture toughness as a
result of fine nano grain structure and the existence of a relatively
soft α-Fe.
Nano composites of cyanate esters were prepared
by dispersing organically modified layered silicates
(OLS) into the resin. Inclusion of only 2.5% by weight
of OLS led to a marked improvement in physical and
thermal properties.
The mechanical response of nano scale materials
and structure has important implications diverse
areas of science spanning topics that include
understanding of biological recognition, development
of light weight structural materials, to exploration of
new concepts for switches and chemical sensors.
Engineering Applications: Composite materials have been used in
aerospace, automobile, and marine applications (see Figs. 1-3). Recently,
composite materials have been increasingly considered in civil engineering
structures. The latter applications include seismic retrofit of bridge columns
(Fig. 4), replacements of deteriorated bridge decks (Fig. 5), and new bridge
structures (Fig. 6).
Figure 1
Figure 4
Figure 2
Figure 5
Figure 3
Figure 6
The nanocrystalline grains should have random orientation (i.e.
high angle grain boundaries) to minimize incoherent strain and
facilitate many nanocrystalline grains to slide in amorphous matrix
to release strain and obtain high toughness.
The amorphous phase must possess high structural flexibility in
order to accommodate coherent strains without forming dangling
bonds, voids, or other defects.
The presence of amorphous phase on the boundaries helps to
deflect and terminate nanocracks in addition addition to the
enhancement of grain boundary sliding, thus
improving coating toughness.
To design a nanocomposite coating with both high hardness and
high toughness, one must take all the above into consideration.
Probably the best way is to use ternary, quaternary or even more
complex systems, with high strength amorphous phase as matrix
(such as a-SiNx, a-BN, a-C, etc.) and hard transition metal-nitride
nanocrystals (such as TiN, W2N, BN, etc.) as nanocrystalline phase
to increase grain boundary complexity and strength.
These nanocrystalline phases should be refractory and immiscible
with each other, and could result in compositional modulation,
segregation and high thermal stability of the nanostructure.
Synthesis methods
Different techniques are now available for preparation of
nanocomposite coatings.
The most promising methods are magnetron sputtering and
chemical vapor deposition
(CVD), although other methods, such as laser ablation , thermal
evaporation , ion beam
Deposition and ion implantation, are also used by various
researchers.
High deposition rate and uniform deposition for complicated
geometries are the advantages of CVD method compared to
sputtering.
However, the main concern for CVD method is that the precursor
gases TiCl4, SiCl4 or SiH4 may pose problems in production
Evaluation of mechanical properties
Good mechanical properties of a coating require high hardness, high toughness,
low friction, high adhesion strength on substrate, good load support capability
and chemical and thermal stability, etc.
Of all these, hardness is probably of number one importance for an industrial
coatings especially in tribological applications.
At present, nanoindentation is regarded as a good method in hardness
determination of thin films and coatings.
In nanoindentation test, a diamond indenter is forced into the coating surface.
The load and depth of penetration (the indentation profile) is recorded, from
which the
hardness and elastic properties are calculated.