The document discusses superconductors, materials with zero electrical resistance first discovered in mercury in 1911. It highlights the properties, types, and applications of superconductors, including the Meissner effect and the BCS theory explaining superconductivity through electron-phonon interactions. Additionally, it covers aspects of nanotechnology and properties of fullerene compounds, such as buckyballs and carbon nanotubes, emphasizing their potential applications in various fields.

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Dr A K Mishra, Academic Coordinator,
JIT Jahangirabad
Engineering Physics II Unit V
Presentation By
Dr.A.K.Mishra
Associate Professor
Jahangirabad Institute of Technology, Barabanki
Email: akmishra.phy@gmail.com
Arun.Kumar@jit.edu.in

2. Superconductors
• In 1911 superconductivity was first observed in mercury by
Dutch physicist Heike Kamerlingh Onnes of Leiden University .
• When he cooled it to the temperature of liquid helium, 4
degrees Kelvin (-452F, -269C), its resistance suddenly
disappeared.
• Later, in 1913, he won a Nobel Prize in physics for his research
in this area.
• Superconductors, materials that have no resistance to the
flow of electricity, are one of the last great frontiers of
scientific discovery
• At the critical temprature the resistance falls to zero
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Dr A K Mishra, Academic Coordinator,
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3. Continued……………..
• These can be used to make low loss power line and very good
electromagnets.
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Temperature (K)
Resistance
TC
O
Temperature (K)
Resistance
4.0 4.1 4.2 4.3 4.4
0.0
1.0
1.5

4. Temperature dependence of resistivity in
superconducting materials
• Superconductivity in the metal are depend on the intensity of
the field and temperature.
• to maintain the Superconductivity both the parameter should
be less than their critical values.
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Normal Metal
Superconductor
Tc0
0

5. Continued……………..
• The dependence of the temperature on magnetic field can be
represented by following equation,
• Where Hc is the critical field strength, Hc(0) is the maximum field
strength at absolute zero and Tc is the critical temperature. it is clear
from the fig the temperature below Tc the materials remains in the
superconducting state till a corresponding critical magnetic field is
applied when the field is higher than the Hc the superconducting
state is destroyed and the materials comes to its normal state.
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Dr A K Mishra, Academic Coordinator,
JIT Jahangirabad
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]
c
-Hc(0)[1=Hc
T
T
2







6. Meissner Effect (Effect of magnetic field)
• When a material makes transition from normal to
superconducting state, it excludes magnetic field from its
interior.
• This phenomenon is called the meissner effect.
• Meissner and Ochsenfield (1953) concluded that when
superconductor is cooled in longitudinal magnetic field,then
above its transition temperature magnetic lines pass through
specimen but below transition temperature the magnetic flux
is pushed out of the specimen,this indicates that below Tc the
metal become perfectely diamagnetic.
• Thus phenomenon of exclusion of magnetic flux from the
interior of a superconductor below Tc is the Meissner effect.
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7. Continued…………
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Below Tc a persistence current generates on the surface and
cancel the flux density inside the superconductor.
Thus for a superconducting state,if B is zero inside the specimen
then we get,

8. Continued…………
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tyconductiviisWhere
E=J
lawOhmsfromNow
c.diamagnetiperfectaisstatectingsuperconduhence
metal,cdiamagnetitheofconditiontheisThis
1-=
H
M
=lity,susceptibiMagnetic
H-=M
M)+(H=0
M)+(H=B
0
0






9. Continued…………
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JIT Jahangirabad
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0=Ei.e.,(J)densitycurrent
infiniteforzerobemustfieldelectriczero,becomes
)(yresistivitequationabovefromclearisIt
J=E
E
1
=J
may writey weresistivitofin termsAgain




10. Continued…………
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ctor.superconduaofproperties
essentialandtindependentwothearesmdiamagneti
perfectandyresistivittheHenceeffect.Meissnerthe
contradictthisTcoftindependenisctorsupercondu
theinsidefluxmagnetictheshowsThis
constant=B0=
t
B
0=EputtingBy
t
B
-=EX
haveweequation,thirdMaxwellfromBut






11. Persistent current
• when an electric current is set in a
superconductor it can persist for long time
without any e.m.f.
• An induced current can flow in a ring of
superconducting material by cooling it in the
presence of magnetic field below Tc and then
remove the field (fig A),the flux outside the
ring disappears but it remains inside the ring
(fig B).
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12. TYPE OF SUPERCONDUCTORS
• Superconductors are divided in to two parts depending on the
mechanism from superconducting state to normal state due
to exceed of critical field.
TYPE I SUPERCONDUCTORS OR SOFT SUPERCONDUCTOR
• Type 1 superconductors - characterized as the "soft"
superconductors - were discovered first and require the
coldest temperatures to become superconductive.
• They exhibit a very sharp transition to a superconducting state
and "perfect" diamagnetism - the ability to repel a magnetic
field completely.
• Type 1 superconductors along with the critical transition
temperature (known as Tc) below which each superconducts.
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13. Continued………..
• Surprisingly, copper, silver and gold, three of the best metallic
conductors, do not rank among the superconductive elements.
For type I superconductor
magnetic flux is expelled
producing magnetization
with increasing field until
is reached, at which it
falls to zero with a normal
conductor.
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Applied Magnetic field (H)
Magnetization(M)
HC
IType
HC
Magnetization(M)
HC
IType

14. TYPE II SUPERCONDUCTORS OR Hard
SUPERCONDUCTOR
• Except for the elements vanadium, technetium and niobium,
the Type 2 category of superconductors is comprised of
metallic compounds and alloys.
• Type II have two critical
field ( & )
below behave as
type I and above
behave as normal
conductor.
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JIT Jahangirabad
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Magnetization(M)
HC
IIType
HC1
HC2
HC1
HC2
HC1
HC2

15. Continued…………..
• This new category of superconductors was identified by L.V.
Shubnikov at the Kharkov Institute of Science and Technology
in the Ukraine in 1936(1) when he found two distinct critical
magnetic fields (known as Hc1 and Hc2) in PbTl2.
• The first of the oxide superconductors was created in 1973 by
DuPont researcher Art Sleight when Ba(Pb,Bi)O3 was found to
have a Tc of 13K.
• Type 2 superconductors - also known as the "hard"
superconductors - differ from Type 1 in that their transition
from a normal to a superconducting state is gradual across a
region of "mixed state" behavior. Since a Type 2 will allow
some penetration by an external magnetic field into its
surface.
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16. London Penetration depth
• According to F.London and H.London,the magnetic field at the
surface of a superconductor does not vanish suddenly but
decays exponentially to zero according to following equation,
Where H0 is the field at the surface, x is the distance from the
surface and λ is the characteristics length known as London
penetration depth.
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e
x


H0=H

17. Continued………….
• The magnetic field at the surface of the superconductor
decays to at a distance in the interior of superconductor.
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e
B 0
x
0x 
x
B0
B
eB
-x
0
(x)B 

18. BCS THEORY
• The first widely accepted quantum mechanical explanation of
superconductivity was presented by J.Barden, L N Copper and
John Schriffer (BCS) in 1957.
• This theory based on the electron-electron interaction via
phonon as a mediator.
• Under certain restricted conditions, the electron couple
together electron-lattice electron interactions.
• Therefore, the electron and phonon interaction is the basic
mechanism responsible for superconductivity.
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19. Continued………….
• Atoms in a crystal lattice are constantly vibrating. Because
they are all connected, these vibrating atoms create waves
throughout the metal.
• These waves are called phonons.
• The more the atoms are vibrating (ie. the hotter the material),
the larger the phonons.
• In superconductors (at low temperatures) the phonons are
small, and any distortion caused by the electrons is reflected
in phonons.
• These phonons can attract electrons to form cooper pairs.
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20. Continued………….
• As shown below the moving electron causes the lattice to
distort and an increased positive charged density is formed
near the electron.
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21. Continued………….
• To counter-act this a second electron is attracted towards the
electron (even though the two electrons repel).
• This pair of electrons are called a Cooper pair, which move
easily through the material.
• This is because their strong negative charge will repel any
positive atoms that it gets close to, thus no collisions occur
and electron flow is not resisted.
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22. Applications of Superconductivity
• The early superconductors were chunks of metal. A breakthrough came in
the 1960s with the development of a superconducting wire, an alloy of
niobium and titanium. With this wire, engineers could wind electromagnet
coils. These superconducting coils permit the construction of extremely
powerful electromagnets. As with many engineering advances, there are
tradeoffs:
Cost Saving: Since the magnet is operated with the wire at
superconducting temperatures, the resistance of the coils is zero and no
energy is lost to heating the coils. For superconducting magnets, a small
power supply is sufficient to initiate the flow of current.
• Cost Increase: Since the coils must be maintained at a low temperature,
an expensive liquid helium refrigeration system is required. The
superconducting magnet coils produce a large and uniform magnetic field
inside the patient's body. Note the large size of the scanner, which
contains the liquid helium refrigeration system.
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23. • Maglev Train
• To minimize friction, powerful onboard superconducting magnets
support this train above the tracks.
• The train reached a speed of 411 km/hr (256 mi/hr). Running
alongside the track are walls (see photo) with a continuous series of
vertical coils of wire mounted inside.
• The wire in these coils is not a superconductor. As the train passes
each coil, the motion of the superconducting magnet on the train
induces a current in these coils, making them electromagnets.
• The electromagnets on the train and outside produce forces that
levitate the train and keep it centered above the track.
• In addition, a wave of electric current sweeps down these outside
coils and propels the train forward .
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24. NANOTECHNOLOGY
• Nanotechnology is the engineering of functional systems at
the molecular scale. 'nanotechnology' refers to the projected
ability to construct items from the bottom up, using techniques
and tools being developed today to make complete, high
performance products.
• Nanomaterials can be fabricated in two ways, top down and
bottom up. In top down nonmaterial's are constructed by
removing existing materials from larger entities. This is used in
manufacturing microprocessors. In bottom up, materials are
built up atom by atom or molecule by molecule. This approach
is more time consuming therefore self assembly process is
usually employed so that atoms spontaneously arrange
themselves into final product.
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25. Properties of nanomaterial's
• Nanomaterials have the following properties:
• They are very hard.
• They are ductile at high temperatures.
• They are chemically very active.
• They are exponentially strong.
• Category of nanomaterials:
• Fullerences
• Nanoparticles
• Fullerences:The third form of carbon was discovered in 1985.it is cluster of
60 carbon atoms like a football.
• Buckministerfullerence the name was given by the architect R.
Buckministerfuller.
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26. Continued……….
• it has carbon atoms at 60 chemically equivalent vertices,
which are connected by 32 faces,12 of which are pentagons
and 20 hexagons.
• These are allotrops of carbon which are basically grapheme
sheets rolled into tubes or spheres,Graphene is a one atom
thick layer of graphite.
• Buckminister C60 is also known as buckyboll,is the smallest
member of the fullerence family. Carbonnanotube (CNT) are
also member of this family.
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27. Continued……….
• Fullerene are produced by sending large current between two
nearby graphite electrodes.
Referred from Google image
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28. Continued……….
• this results into carbon plasma arc between
electrodes, which gives fullerence on cooling.
• Buckminsterfullerene C60, also known as the
buckyball, is a representative member of the carbon
structures known as fullerenes.
• Members of the fullerene family are a major subject
of research falling under the nanotechnology
umbrella.
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29. Production of Buckyballs
• Buckyballs can be produced by vaporizing carbon
placed between two carbon electrodes.
• when electric arc is produced between electrodes
placed in the vicinity of each other in a low pressure
reaction chamber,buckyballs generated along the
carbon.
• They can be separated with the help of solvent like
benzene.
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30. Properties of Buckyballs
• Buckyballs can be used in many applications
because of their unusual hollow structure.
• Buckyballs are extremely stable, and can bear
very high temperature and pressure.
• Even after reaction with other atoms and
molecules, their stable spherical structure
remains intact.
• Addition of other molecules at the outside and
trapping of smaller molecules inside a buckyball
creates new molecule.
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31. Uses of Buckyballs
• Buckyballs becomes a superconductor when dopped with a
little amount of potassium or cesium.this is the best
superconductor known to us.
• Buckyballs can better storage of hydrogen because when
the C60 molecules absorb one molecule of hydrogen, its
structure does not disrupt.
• Bucky balls can deliver drugs directly to the infected region
of the body, they also have the ability to act as
antioxidants, thereby counteracting free radicals in the
human body.
• Anti- ageing and anti-wrinkle creams are being
manufactured by using buck balls.
• Bucky balls are also used as cutting tools.
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32. Carbon Nano tubes (CNTs)
• Carbon nanotubes were first discovered by Somio
Iijima in 1991. cnt belongs to the family of
graphite.
• the structure of graphite is one-atom thick planar
network of interconnected hexagonal ring of
carbon atoms.
• these sheets of carbon are staked on the top of
one another such that they are able to slide over
each other. This is responsible for the softness of
graphite; hence graphite can be used as a
lubricant.
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33. Continued……………..
• When graphite sheets are rolled into cylinder and their edges
are joined they form carbon nanotubes.
What is a Carbon Nanotube:
A Carbon Nanotube is a tube-shaped material, made of
carbon, having a diameter measuring on the nanometer scale.
A nanometer is one-billionth of a meter, or about one ten-
thousandth of the thickness of a human hair. The graphite
layer appears somewhat like a rolled-up chicken wire with a
continuous unbroken hexagonal mesh and carbon molecules
at the apexes of the hexagons.
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34. Continued……………..
• Carbon Nanotubes have many structures, differing in
length, thickness, and in the type of helicity and number
of layers. Although they are formed from essentially the
same graphite sheet, their electrical characteristics differ
depending on these variations, acting either as metals or
as semiconductors.
• As a group, Carbon Nanotubes typically have diameters
ranging from <1 nm up to 50 nm. Their lengths are
typically several microns, but recent advancements have
made the nanotubes much longer, and measured in
centimeters.
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35. Continued……………
• Carbon Nanotubes can be categorized by their
structures.
• Single-wall Nanotubes (SWNT)
• Multi-wall Nanotubes (MWNT)
• Double-wall Nanotubes (DWNT)
• What are the Properties of a Carbon
Nanotube?
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36. Continued………….
• The intrinsic mechanical and transport properties of Carbon
Nanotubes make them the ultimate carbon fibers. Overall,
Carbon Nanotubes show a unique combination of stiffness,
strength, and tenacity compared to other fiber materials
which usually lack one or more of these properties. Thermal
and electrical conductivity are also very high, and comparable
to other conductive materials.
• What are the Potential Applications for Carbon Nanotubes?
Carbon Nanotube Technology can be used for a wide range of
new and existing applications:
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37. Continued………….
• Conductive plastics
• Structural composite materials
• Flat-panel displays
• Gas storage
• Antifouling paint
• Micro- and nano-electronics
• Radar-absorbing coating
• Technical textiles
• Ultra-capacitors
• Atomic Force Microscope (AFM) tips
• Batteries with improved lifetime
• Biosensors for harmful gases
• Extra strong fibers
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38. Continued………….
• Nanocyl uses the "Catalytic Carbon Vapor
Deposition" method for producing Carbon
Nanotube Technologies. This proven industrial
process is well known for its reliability and
scalability. It involves growing nanotubes on
substrates, thus enabling uniform, large-scale
production of the highest-quality carbon
nanotubes worldwide.
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