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Carmine SENATORE
Superconductivity and its applications
Lecture 9
http://supra.unige.ch
Group of Applied SuperconductivityDepartment of Quantum Matter Physics
University of Geneva, Switzerland
Bi2212 Bi2223
a [Å] 5.415 5.413
b [Å] 5.421 5.421
c [Å] 30.880 37.010
# of adjacent CuO2 planes
2 3
Tc [K] 91 110Bi2212
Bi2Sr2CaCu2O8+x
Bi2223Bi2Sr2Ca2Cu3O10+x
3 CuO2 planes 2 CuO2 planes
O
Ca
Cu
Sr
Bi
Previously, in lecture 8 - HTS materials for applications
Previously, in lecture 8HTS materials for applications
Copper oxides with highly anisotropic structures, texturing (grain orientation) is required in technical superconductors
Produced by Powder-In-Tube methodAg matrix materialTape geometry to achieve c-axis texturingIc depends on the magnetic field orientation
Produced by Powder-In-Tube methodAg matrix materialRound wire, spontaneous radial texturing of the c-axisIsotropic properties of Ic
Tc [K] texture
Bi2223 110 c-axis
Bi2212 91c-axis
(radial)
Bi2223 route
Bi2212 route
Bi2212 conductors are multifilamentary round wires
Previously, in lecture 8
Bi2212 & Bi 2223 conductor technology
Bi2223 conductors are multifilamentary tapes
Bi2212 Bi2223 Y123
a [Å] 5.415 5.413 3.8227
b [Å] 5.421 5.421 3.8872
c [Å] 30.880 37.010 11.680
# of adjacent CuO2 planes
2 3 2
Tc [K] 91 110 92Bi2212
Bi2Sr2CaCu2O8+x
Bi2223Bi2Sr2Ca2Cu3O10+x
Y123YBa2Cu3O7-x
3 CuO2 planes
2 CuO2 planes
CuO chains
2 CuO2 planes
O
Ca
Cu
Sr
Bi
O
Cu
Y
Ba
Previously, in lecture 8 - HTS materials for applications
1.02b
a
in BSCCO1.001b
a
in YBCO
Grain boundaries in Y123
Hilgenkamp and Mannhart, RMP 74 (2002) 485
[001] tilt boundary
[100] tilt boundary
[100] twist boundary
For angles above 8-10°, the JcGB is reduced by a factor >100 !!
In order to get high Jc in the conductor, the c-axis texturing is not enough
We do need also texturing in the ab plane
HTS conductors: texturing in Bi2223 and Y123
Both in Bi2223 and Y123, c-axis texturing is required due to the anisotropy of the properties //ab and //c
Because of the Jc dependence on the GB angle in the ab plane, also in-plane texturing is required for Y123
a
b
b
ba
a
b
ab
a
a
b
a
b
a
b
a
b
a a
b
a
b
current current
Bi2223 Y123
This biaxial texture is required over kilometers!!
YBCO (REBCO) coated conductors
Ag cap layer
Cu stabilisation
REBCO layer metallic substratebuffer layers
~1 µm of REBCO in a ~100 µm thick tape
Biaxial texturing – within < 3° – is obtained
a
b
a
b
a
b
a
b
a a
b
a
b
Looking from above
The template is a metallic substrate coated with a multifunctional oxide barrier
Goyal et al., APL 69 (1996) 1795
Iijima et al., APL 60 (1992) 769
Presently produced by
• complex and expensive manufacturing process
• pronounced anisotropic behaviour
but with some also drawbacks:
The technology of REBCO coated conductorsAlternative approaches for growing epitaxial REBCO on flexible metallic substrates in km-lengths
Substrate texturing
RABiTS : Rolling-Assisted, Biaxially Textured Substrates
Texture is created in NiW by a rolling-and-recrystallization process
IBAD : Ion Beam Assisted DepositionA biaxially textured MgO layer is grown on polycrystalline Hastelloy
REBCO layer deposition
Physical routes
Chemical routes
PLD Pulsed Laser Deposition
RCE Reactive Co-Evaporation
MOD Metal-Organic Deposition
MOCVD Metal-Organic Chemical Vapor Dep.
REBCO conductor technology: RABiTS template
RABiTS : Rolling-Assisted, Biaxially Textured Substrates
• [100] cube texture is created in the NiW substrate by a rolling-and-recrystallization process
• Several epitaxial buffer layers are needed to provide a lattice matched surface for growing the HTS layer
REBCO conductor technology: IBAD template
IBAD : Ion Beam Assisted Deposition
• A biaxially textured MgO layer is grown on a polycrystalline Hastelloy tape
• Several other buffer layers are needed to provide a lattice matched surface for growing the HTS layer
Performance overview: Jc(s.f.,77K) vs. Jc(19T,4.2K)
2.5 10 1005
10
100
STI
15 mol % Zr
SuperPower M3
J c-la
yer
(19
T,4
.2K
) [k
A/m
m2]
Jc-layer
(s.f.,77K) [kA/mm2]
BHTS T150
BHTS T2289
BHTS T2291
BHTS T003
SuperOx
AMSC
Fujikura
SuNAM
SuperPower M4
BHTS T002
BHTS T2290
15 mol. % Zr-added (Y,Gd)BCO Xu et al., APL Mat. 2 (2014) 046111
Artificial pinning to enhance REBCO performanceIntroduction of artificial nano-defects to control vortex pinning, reduce anisotropy and enhance performance
BaZrO3 (BZO) precipitates are in form of nano-columns oriented along the c-axis
Driscoll et al., Nat. Mat. 3 (2004) 439
Goyal et al., SuST 18 (2005) 1533 0 30 60 90 120 150 180 210 240
2
3
4
5
6
7
8
9
10
@ 77 K, 1 T
J c (
1 T
,77
K)
[kA
/mm
2]
Angle between field and c-axis [°]
standard REBCO
REBCO + BZO nanocolumns
0 30 60 90 120 150 180 210 2402
3
4
5
6
7
8
9
10
@ 77 K, 1 T
J c (
1 T
,77
K)
[kA
/mm
2]
Angle between field and c-axis [°]
standard REBCO
Selvamanickam et al., IEEE TAS 21 (2011) 3049
On the BZO nanorods morphology
Average BZO size 5.5 nmAverage spacing ~ 12 nmDensity = 6.9 × 1011 cm-2
Selvamanickam el al., APL 106 (2015) 032601
No loss of BZO alignment in 2.2 μmthick films
Engineering vs. superconducting layer performance
0 5 10 15 20100
1000
5000
Bi2223
Bi2212
BHTS REBCO B tape - UNIGE
OST Bi2212 - Larbalestier et al.(2014)
Sumitomo Bi2223 B tape - UNIGE
@ 4.2 K
J eng [
A/m
m2]
Magnetic field [T]
REBCO
Engineering current density
0 5 10 15 20
1
10
100
1000
Bi2223
Bi2212
BHTS REBCO B tape - UNIGE
OST Bi2212 - Larbalestier et al.(2014)
Sumitomo Bi2223 B tape - UNIGE
@ 4.2 K
J c [kA
/mm
2]
Magnetic field [T]
REBCO
Critical current density
REBCO and Bi2223 tapes retain the anisotropic properties of the superconductor
Data shown here correspond to the unfavorable orientation wrt the field
The in-field properties of Bi2212 wires are fully isotropic
Industrial superconductors
React&Wind vs Wind&React
React&Wind Wind&React
in situ MgB2
Nb3Sn
IMD MgB2
Bi2212
NbTi
ex situ MgB2
Bi2223
Y123
How to choose the superconductor: Performance vs Cost
0 5 10 15 20 250
50
100
150
200
@ 4.2 K Nb3SnNb-Ti
Bi2212
YBCO B//ab
YBCO B//c
Pri
ce/p
erf
orm
ance
($
/kA
m)
Magnetic field (T)
Copper
Adapted from B. Seeber, IEEE TASC 28 (2018) 6900305
engJ kkA m g
$ $
Superconductor TechnologyBasic design and operation issues of a superconducting device
Superconducting magnets, field shapes and winding configurations
• Solenoids (NMR, MRI and laboratory magnets)
• Transverse fields (particle accelerators)
• Toroids (fusion magnets)
Solenoids: concepts and design
0
34C
Idl rB r
r
Biot-Savart law
* Overall current density, normalized to the winding section including wire matrix and insulation
0 ,B JaF
In the case of a solenoid
2 2
02
, ln1 1
F
l
a
b
a with and
2 ( )
NIJ
l b a
where *
B0
A given field can always be made by a short fat coil or a long thin one
/b a
l
a
2 22 ( )V l b a
3 22 ( 1)a
Coil geometry and shape factor
0 ,B JaF
B0Bw
Maximum field on the winding
l
a
b
a
and have an influence on the field uniformity
At the exercise session: how to choose and when designing a solenoid
B0
Homogeneity of the field along z
0 ,B JaF
b
a
l
a
l+z
l-z
zB 1
1,
2JaF 2
1,
2JaF
where and
z
Bz
How to calculate the variation of field along the axis of a solenoid
1
l z
a
2
l z
a
Homogeneity of the field along z
Along the solenoid axis
2 4 6
0 2 4 61 ...z
z z zB B E E E
a a a
By suitable adjustment of coil shape, one may reduce an error coefficient to zero
2 4 0E E
This notched solenoid is of sixth order
2
2 20
1 1
2 !
nz
n n
d BE
B n dz
A 32 T all-superconducting magnet at NHMFL, US
Subdivide the winding into a numberof concentric sections to improve theefficiency of superconductor utilization
Each section operates at the maximumcurrent density allowed by the localfield level
All sections take the same current, buteach section has its own J, and
General guidelines for magnet design
Recommended