Zero resistance superconductivity

1. Introduction
 Superconductivity is the phenomenon of exactly
zero electrical resistance.
 Expulsion of magnetic fields occurring in certain
material when cooled below a characteristic
critical temperature.
 It is a quantum mechanical phenomenon.
 It was discovered by
HEIKE KAMMERLINGH ONNES.
(1853-1926)
 He discovered that the resistivity
of mercury disappears at
temperature below about 4.2K.
 A normal conductor can be brought
into superconducting state by
increasing it’s preasure.
What Is Superconductivity ?
Superconductivity is phenomenon of zero electrical
Resistance & expulsion of magnetic field occurring in
certain materials when cooled below a characteristic
critical temperature (Tc).
The temperature at which electrical resistance
Is zero is called CRITICAL TEMPERATURE (Tc)
Occurrence Of Superconductivity
Superconducting Elements Tc (K)
Sn (Tin) 3.72
Hg (Mercury) 4.15
Pb (Lead) 7.19
NbTi (Niobium Titanium) 10
Nb3Sn (Niobium Tin) 18.1
CeCu2Si2 <1
Ba0.63K0.37BiO3 , SrTiO3-d <30
YBCO, BSCCO, HBCCO <165
General Properties of
Superconductor
 Virtually zero electrical resistance.
 Perfect diamagnetic property.
 Critical Field depends upon temperature of
superconducting material.
 Heavy Current effect destroys superconducting
properties.
 At very high pressure Tc is directly proportional to
pressure.
 Tc is inversely proportional to squre root of At.wt of
the isotope of single superconductor.
High Tc Superconductors
 In a superconductor if the transition is high
ie., greater than 20K, then it is called as high
temperature superconductors.
 In 1986, Muller and Bednorz discovered high
temperature super conductor
in ceramics.
Structure
“Zero Resistance” - Is It
Possible?
In a normal conductor, an electric current may be
Visualized as a flow of electrons moving across a heavy
Ionic lattice. The electrons are constantly colliding
with the ions in the lattice, and during each collision
some of the energy carried by the electrons is absorbed
by the lattice and converted into heat, which is
Essentially the vibrational kinetic energy of the lattice
ions. As a result, the energy carried by the current
is constantly being dissipated. This is the
Phenomenon of electrical resistance.
In superconductors the situation is completely different
Types of superconductors
Type 1 Type 2
• Exhibit Meissner Effect
• Behave as a perfect
diamagnetic material
• No mixed state in present
• Sudden loss of
magnetization
• Soft superconductor
• There is only one Hc
• Ex., Pb, Sn, Hg
• Does not exhibit
complete
Meissner Effect.
• Does not behave as a
perfect diamagnetic
material.
• Mixed state present
• Gradual loss of
magnetization
• Hard superconductor
• There are two HCs-HC1 &
HC2
• Ex., NbSn, NbTi
Meissner Effect
 Magnetic lines of force penetrate through a normal
conducting material when placed in a magnetic field
of flux density B.
 Whereas, a superconducting material repels the
magnetic field & thus behaves as a diamagnetic
material.
 A superconducting material also ejects magnetic lines
of force when cooled for superconductivity.
Normal State Superconducting
State
T>Tc T<Tc
H>Hc H<Hc
Advantages/Disadvantages
1) Advantages
 Can carry large quantities of energy without heat loss.
 Able to generate strong magnetic fields.
 Superconductors beneficial applications in medical
imaging techniques.
 New superconductive films may result in
miniaturization
 Superconductors increased speed in computer chips.
 No need of initial in case of magnet for low speeds.
 One litter of liquid nitrogen costs less than one litter
of mineral water.
2) Disadvantages
 Superconducting materials conduct current at only
give temperature known as transition temperature.
 Superconductors still do not show up in most
everyday electronics.
Conclusion
The purpose of this presentation was the study
of surge current protection using superconductors. The
Superconductor Fault Current Limiters offers efficient
advantages to power systems and opens up a major
application for superconducting materials.
Applications of
Superconductivity
a) Superconducting generator
 Converts mechanical to electrical energy.
 Own magnetic field is produced.
 Current and flux density determines the output.
 Field windings produces higher magnetic field.
 Superconductors have extremely high current
carrying capacity.
b) Superconducting transmission line cables
 Provides ZERO resistance.
 Due to LOW VOLTAGE, high current transmission
occurs.
 SMALL physical size.
 Reduced CLEARANCE for terminal faculties.
 Quick RECOVERY after fault.
 Overload capacity.
c) Superconducting magnetic energy stored system
 Current carrying wire generates a magnetic field.
 Superconducting solenoids made by wrapping a
superconducting wire in the coil from are
functionally superior to conventional solenoids.
 Zero DC electrical resistance.
 No resistive losses.
Noble Prizes for Superconductivity
Heike Kamerlingh onnes (1913)
 Leon N. Cooper, J. Robert Schrieffer (1972)
Leo Esaki, Ivar Giaever, Brian D. Josephson (1973)
Georg Bdnorz (1987)
Alexei A. Abrikosov, Anthony J. Leggett (2003)
References
1. John Bardeen; Leon Coop; J.R. Schriffer (December 1,
1957). “Theory of Superconductivity”
2. John Daintith (2009). “The Facts on File Dictionary of
Physics” (4th ed.).
3. John C. Gallop (1990). SQUIDS, the Josephson Effects
and Superconducting Electronics.
4. “All Nobal Prizes in Physics”. Nobalprize.org
Presented By
 Yash Contractor (160220109006)
 Kundan Parmar (160220109027)
 Smit Prajapati (160220109050)
 Vijay Prajapati (160220109051)
 Bijohn Joseph (160220109001)