Learn about superconducting material and it's properties and it's invention also it's application

1. SUPERCONDUCTING MATERIALS
Superconductivity - The phenomenon of losing resistivity wh
en sufficiently cooled to a very low temperature (below a cer
tain critical temperature).
 H. Kammerlingh Onnes – 1911 – Pure Mercury
Resistance (Ω)
4.0 4.1 4.2 4.3 4.4
Temperature (K)
0.15
0.10
0.0
Tc

2. SUPERCONDUCTORS
• Superconductivity is a pheno
menon in certain materials at extr
emely low temperatures ,charact
erized by exactly zero electrical re
sistance and exclusion of the inter
ior magnetic field (i.e. the Meissn
er effect)
• This phenomenon is nothing bu
t losing the resistivity absolutely
when cooled to sufficient low tem
peratures

3. Transition Temperature or Critical Temperature (TC)
Temperature at which a normal conductor lose
s its resistivity and becomes a superconductor.
• Very good electrical conductors not supercond
uctors eg. Cu, Ag, Au
TYPES
1. Low TC superconductors
2. High TC superconductors

4. Occurrence of Superconductivity
Superconducting Elements TC (K)
Sn (Tin) 3.72
Hg (Mercury) 4.15
Pb (Lead) 7.19
Superconducting Compounds
NbTi (Niobium Titanium) 10
Nb3Sn (Niobium Tin) 18.1

5. Properties of Superconductors
Electrical Resistance
• Zero Electrical Resi
stance
• Critical Temperatur
e
• Quickest test
• 10-5Ωcm

6. Effect of Magnetic Field
Critical magnetic field (HC) – Mini
mum magnetic field required t
o destroy the superconducting
property at any temperature
H0 – Critical field at 0K
T - Temperature below TC
TC - Transition Temperature
Superconducting
Normal
T (K) TC
H0
HC
Element HC at 0K
(mT)
Nb 198
Pb 80.3
Sn 30.92
0 1C
C
T
H H
T
  
   
   

7. Stress
• Stress ↑, dimension ↑, TC ↑, HC affected
Frequency
• Frequency ↑, Zero resistance – modified, TC not
affected
Impurities
• Magnetic properties affected
Size
• Size < 10-4cm – superconducting state modified

8. GENERAL PROPERTIES
No change in crystal structure
No change in elastic & photo-elect
ric properties
No change in volume at TC in the a
bsence of magnetic field

9. Types of Superconductors
Type I
• Sudden loss of magnetisation
• Exhibit Meissner Effect
• One HC = 0.1 tesla
• No mixed state
• Soft superconductor
• Eg.s – Pb, Sn, Hg
Type II
• Gradual loss of magnetisation
• Does not exhibit complete Meissn
er Effect
• Two HCs – HC1 & HC2 (≈30 tesla)
• Mixed state present
• Hard superconductor
• Eg.s – Nb-Sn, Nb-Ti
-M
HHC
Superconducting
Normal
Superconducting
-M
Normal
Mixed
HC1 HC
HC2
H

10. APPLICATIONSOF
SUPER CONDUCT
ORS

11. Applications
• Large distance power transmission (ρ = 0)
• Switching device (easy destruction of supe
rconductivity)
• Sensitive electrical equipment (small V var
iation  large constant current)
• Memory / Storage element (persistent curr
ent)
• Highly efficient small sized electrical gener
ator and transformer

12. Medical Applications
•NMR – Nuclear Magnetic Resonance – Sca
nning
•Brain wave activity – brain tumour, defectiv
e cells
•Separate damaged cells and healthy cells
•Superconducting solenoids – magneto hydr
odynamic power generation – plasma maint
enance

13. Transmission of power
Switching devices
Sensitive electrical instruments
Memory (or) storage element in computers
.
Manufacture of electrical generators and tr
ansformers
 Magnetic levitated trains.
Engineering

14. Magnetic Levitated Train
Principle: Electro-magnetic induction
Introduction:
Magnetic levitation transport is a form of transport
ation that suspends, guides and propels vehicles via
electromagnetic force. This method can be faster tha
n wheeled mass transit systems, potentially reaching
velocities comparable to turboprop and jet aircraft (5
00 to 580 km/h).

15. Electrodynamic suspension
In Electrodynamic suspension (EDS), both the rail and the train exer
t a magnetic field, and the train is levitated by the repulsive force bet
ween these magnetic fields. The magnetic field in the train is produc
ed by either electromagnets or by an array of permanent magnets.
The repulsive force in the track is created by an induced magnetic fi
eld in wires or other conducting strips in the track.
At slow speeds, the current induced in these coils and the resultant
magnetic flux is not large enough to support the weight of the train.
For this reason the train must have wheels or some other form of la
nding gear to support the train until it reaches a speed that can sust
ain levitation.
Propulsion coils on the guideway are used to exert a force on the m
agnets in the train and make the train move forwards.

16. Diagrammatic representation
of magnetic levitate train

17. Advantages
 No need of initial energy in case of magnets
for low speeds
One litre of Liquid nitrogen costs less than on
e litre of mineral water
These trains can attain very high speeds (500
km/h); no wheels or secondary propulsion syste
m needed
 Free of friction as it is “Levitating”.