Superconducting materials have greater significance in present era. This phenomena must be studied completely logical and if knowledge about SC is fetched a little its very interesting to go ahead. In recent years this property of materials are developed and obtained clearly, they are completely implemented in transportation, switching etc., This slides can give you basics in superconducting behavior and materials. Trends have been made to use them in everyday and it gives user friendly behavior.

1. SUPERCONDUCTING
MATERIALS
Presentation
by, Sharmili.P

2. FUNDAMENTAL IDEA:
Superconductors are the materials whose
resistance become immeasurably small or
actually become zero below a certain
temperature, when cooled. Exhibited
phenomena is called ‘Superconductivity’
Phenomena first observed by a Dutch
scientist, Heike Kammerlingh Onnes.
 Materials first in which this property was
observed – liquid helium, liquid nitrogen.

3. DEFINED – Tc :
Tc - Indicates the transition
temperature/Critical Temperature of a
material or a system.
Below a certain “critical” temperature,
materials undergo transition into the
superconducting state.

4. PROPERTIES OF
SUPERCONDUCTORS:
Characterized by properties:
(i) They offer no resistance to the passage
of electrical current.
(ii) Magnetic field effect and
Hc(superconductivity destroyed <Hc ).
(iii) Effect of heavy current
(superconductivity destroyed at sufficient
current).
(iv) Effect of Pressure (Tc ∝ Pressure
applied).

5. THE MEISSNER EFFECT:
When resistance falls to zero, a current can
circulate inside the material without any
dissipation of energy and the expulsion of
a magnetic field from a superconductor
occurs during the superconducting state.

6. Superconductors in the Meissner state
exhibit perfect diamagnetism, or
superdiamagnetism.
Mean that the total magnetic field is very
close to zero deep inside them.
Comparably small/zero resistance would
imply that if you tried to magnetize a
superconductor, current loops would be
generated to exactly cancel the imposed
field.
Significant phase in superconductivity.

7. BCS THEORY:
American researchers - John Bardeen,
Leon Cooper and John Schrieffer -
established this theory of superconductivity.
 BCS theory explained superconductivity at
temperatures close to absolute zero for
elements and simple alloys.
According to their “BCS” theory, electrons
group into pairs through interaction with
vibrations of the lattice, so-called
“phonons” and forms “Cooper pairs”

8. During electron-phonon-electron interaction
they take up energy exchange process.

9. TYPE I AND II
SUPERCONDUCTORS:
Type I: Exhibits perfect diamagnetism
below transition temperature, Tc.
Superconductivity is abruptly destroyed in
this type. They exhibit one critical magnetic
field, Bc.

10. Type II: Totally expels and excludes
magnetic flux below lower critical field, Bc1
and partially does so between Bc1 and upper
critical field, Bc2. This type has a larger Tc
than Type I superconductor.

11. JOSEPHSON TUNNELLING:

12. A current flows indefinitely long without
any voltage applied, across a device with
two superconductors coupled and provided
with a weak link.
Here electrons flow is in pair form.
Electron flow as cooper pair occurs even in
absence of applied external field.
 DC Josephson and AC Josephson effect.
Applied in purposes to produce microwave
radiations with desirable frequency.

13. APPLICATION OF SUPERCONDUCTORS:
HIGH TEMPERATURE
SUPERCONDUCTORS:
High-temperature superconductors
(abbreviated high-Tc or HTS) are materials
that behave as superconductors at unusually
high temperatures. E.g.: Few metal
oxides/ceramics.
CRYOTRON:
A magnetically operated current
switch/particle oscillator. Applied significantly
in electrical/computer field.

14. SQUID(Superconducting Quantum
Interference Devices):
Squids in the most systems acts as
powerful magnetometers, even the weaker
zones. For instance, squids are sensitive
enough to measure the magnetic activity of
the human brain.
MAGNETIC LEVITATION:
Vehicle travels along a guideway
provided with magnets to control in-flight
stability and create propulsion and lift,
eliminating the mechanical constraints.