Type 1 superconductors exhibit complete expulsion of magnetic fields and have low critical magnetic field values, while type 2 superconductors exhibit partial expulsion and have two critical field values between which they are in a mixed or vortex state. Type 1 superconductors like aluminum and lead are called "soft" while type 2 like yttrium barium copper oxide are called "hard" due to their higher critical fields. Magnetic resonance imaging uses the type 2 superconductor niobium-titanium which is superconducting below 9.4 Kelvin, while higher field devices use niobium-tin or emerging magnesium diboride.

1. Dhananjaysinh Jhala
CE 1
ID 41
Enr 27

2.  Superconductors that exhibit complete
meissner effect[complete expulsion of all
magnetic field] are type 1 superconductors.
 They have low Hc [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.  As seen from
magnetization
curve, transition
at Hc is reversible
i.e if field is again
lowered below Hc
then material
again becomes
superconductor.

4.  Superconductors that exhibit partial meissner
effect are type 2 superconductors.
 They have Hc1 [lower magnetic field] & Hc2
[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 Hc2, Tc are high for type 2 superconductors
they are widely used in engineering applications.
 E.g. YBCO, Nb3Sn, Nb3Ge, …

5.  As seen from
magnetization
curve, transition at
Hc is not reversible.

6.  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 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. 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 TaSi2
Type 2
SC
Tc [K] Hc[T]
Nb3Sn 18.05 24.5
Nb3Ge 23.2 38
YBCO 93-95 300
Yttrium barium copper
oxide (YBCO) or 123 oxide was
1st type 2 SC with such high Tc

11.  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.  Bismuth strontium calcium copper oxide,
or BSCCO (pronounced "bisko"), is a family
of high-temperature superconductors having
the generalized chemical
formula Bi2Sr2Can−1CunO2n+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 Tc
and Hc2 is 200 ± 25 T