type1,2 superconductors

ppt on type 1 and type 2 superconductors made in physics subject[GTU]

1. Type 1 & Type 2 Super conducting Materials . Dhananjaysinh Jhala CE 1 ID 41 Enr 27

2. Type 1 superconductors Superconductors that exhibit complete meissner effect[complete expulsion of all magnetic field] are type 1 superconductors. They have low H c [critical magnetic field] values. Due to their tendency to allow field penetration even for lower applied field they are also called “soft superconductors” E.g. pure elements like Al, Lead, Hg, …

3. Magnetization curve for type 1 Superconductors As seen from magnetization curve, transition at H c is reversible i.e if field is again lowered below H c then material again becomes superconductor.

4. Type 2 superconductors Superconductors that exhibit partial meissner effect are type 2 superconductors. They have H c1 [lower magnetic field] & H c2 [upper magnetic field]. In region between them it is in vortex/mixed state. Since they need large magnetic field to bring them back to superconducting state they are also called “hard superconductors” As H c2 , T c are high for type 2 superconductors they are widely used in engineering applications. E.g. YBCO, Nb 3 Sn, Nb 3 Ge, …

5. Magnetization curve for type 2 Superconductors As seen from magnetization curve, transition at H c is not reversible.

6. Vortex state When a magnetic field is applied (in black). Superconducting currents (in red) develop on the surface in order to make a screen against this field. Other superconducting currents develop (in green) creating vortices (like non superconducting “tunnels”).  These vortices allow a quantum of magnetic flux to go through them and thus enable part of the applied magnetic field to go through the superconducting sample.  Because of these vortices, the superconductor becomes a sieve which enables part of the applied magnetic field to pass through. This state is called the mixed state/vortex state.

7. Vortices in a 200-nm-thick YBCO film imaged by scanning SQUID microscopy

8. Flux pinning Flux pinning  is the phenomenon where a superconductor is pinned in space above a magnet. The superconductor must be a type-II superconductor because type-I superconductors cannot be penetrated by magnetic fields. Since the superconductor is pinned above the magnet away from any surfaces, there is the potential for a frictionless joint. The worth of flux pinning is seen through many implementations such as lifts, frictionless joints, and transportation.

9. Examples Type 1 SC Tc [K] Hc[T] Sn 3.72 0.030 Hg 4.15 0.041 Ta 4.47 0.083 V 5.40 0.14 Pb 7.19 0.08 The only alloy which is type 1 SC is TaSi 2 Type 2 SC Tc [K] Hc[T] Nb 3 Sn 18.05 24.5 Nb 3 Ge 23.2 38 YBCO 93-95 300 Yttrium barium copper oxide  ( YBCO ) or 123 oxide was 1st type 2 SC with such high Tc

10. Comparison b/w type1,2 superconductors

11. MRI SCANNER Magnetic resonance imaging  ( MRI ) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease.  The conductor used in nearly all modern superconducting MR scanners is  niobium-titanium (NbTi)  that becomes superconductive below 9.4°K.

12. Scanners and spectrometers with field strengths greater than 10T frequently use a   niobium-tin (Nb3Sn)  alloy. Magnesium diboride (MgB2)  is also emerging as a new superconducting material for scanners and other magnetic instruments because of its much higher transition temperature (39°K).

13. About bscco Bismuth strontium calcium copper oxide , or  BSCCO  (pronounced " bisko "), is a family of high-temperature superconductors having the generalized chemical formula Bi 2 Sr 2 Ca n −1 Cu n O 2 n +4+ x , with  n  = 2 being the most commonly studied  BSCCO was the first HTS material to be used for making practical superconducting wires.  BSCCO is a cuprate perovskite, type 2 superconducting material and have high T c and H c2 is 200 ± 25 T

14. BSCCO