g. grasso, a. malagoli, m. modica, v. braccini, a. tumino, s. roncallo, e. bellingeri, c....
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![Page 1: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/1.jpg)
G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri
INFM -LAMIA, Corso Perrone 24, 16152 Genova -Genova, Via Dodecaneso 33, 16146 Genova
Preparation and properties of MgB2 superconducting tapes
![Page 2: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/2.jpg)
tube filling
PIT Processing routes for the fabrication of MgB2 wires
+B Mg
a)IN-SITU
b) +B Mg MgB2 EX-SITU
wire drawing
wire rolling
Cold Working
long lengths of tape
![Page 3: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/3.jpg)
Cu-sheathed tape
transverse cross section
Tube filling with MgB2 reacted powders
Wire drawing and/or rolling
Flat rolling
Long lengths can be now fabricated
irregular cross section
No sintering is necessary!APL 79 (2001) 230
Alfa-Aesar or homemade precursors
ex-situ PIT processing
High critical currents are achieved even without any sintering process!
1 10 100
0
1x10-5
2x10-5
3x10-5
4x10-5
Ag f.f. 30% Cu f.f. 30% Ni f.f. 30%
Vol
tage
(V
)
Current (A)
I-V characteristics vs. sheath material
4.2 K
.25x3 mm2
strength
![Page 4: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/4.jpg)
Harder sheath material larger jc
Less sausaging + higher powder compactionLow powder compaction => lower Ic and jc
240A 105 A/cm2
0.32 x 4 mm2
f. f. 17%
V-I characteristics at 4.2 K, self field
1 10 100 300
0
1x10-5
2x10-5
3x10-5
4x10-5
Ag f.f. 30% Cu f.f. 30% Ni f.f. 30% Ni f.f. 20%
Vol
tage
(V
)
Current (A)
strength
f.f.
![Page 5: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/5.jpg)
Mechanical properties of unsintered tapes
Unsintered SUS316 MgB2 tapeKitaguchi et al. submitted to Phys. C
200 210 220 230 240 2500
2x10-5
4x10-5
6x10-5
8x10-5
diam. 30 mm
Vol
tage
[V]
I [A]
before bending after bending
Preliminary bending strain experiment
Tape double bent on diameter 30 mm No reduction of Ic
Mechanical properties are already sufficient for applications!
![Page 6: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/6.jpg)
Transport jc(B,T) measurements on unsintered MgB2 tapes
0 2 4 6 8 100
2
4
6
8
10
20 K
15 K10 K
8 K
4.2 K
j c0.5 B
0.25
Magnetic Field [Tesla]
Kramer plot
Jc(B,T)0.5 B0.25 B
Thanks to ENEA-Frascati Lab, Rome, Italy (M. Spadoni, P. Gislon)
0 1 2 3 4 5 62
10
100
300
103
104
105
C
ritic
al c
urre
nt [A
]
Magnetic Field [T]
4.2 K 8 K 10 K 15 K 20 K
Critical current density [A
/cm2]
B//tape plane
Tc lower than expected for MgB2
Magnetoresistance measurements
Btape plane
![Page 7: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/7.jpg)
0 10 20 30 40
0
2
4
6
8
10
Hirr [T
]
T [K]
Ni tape IL from R(B,T) Ni tape IL from I
c(B,T)
precursor MgB2 powders
IL of Ni-sheathed tape presents a larger slope than for MgB2 powders
Irreversibility lines from R , Ic(B,T)
Superconducting irreversibility line and XRD of unsintered MgB2 tapes
A new source of pinning centers is present in ex-situ MgB2 tapes
XRD peaks are broader in the Nickel-sheathed MgB2 filament; some level
of c-axis texture is also present
30 40 50 600
1x103
2x103
3x103
Ni-sheathedMgB
2 filament
MgB2
powders
Al
Al
Al
111
MgO 10
2110
002
101
100
001
Inte
nsity
[a.u
.]
2 [°]
XRD of Ni-sheathed tape
large lattice distortion: a/a = 0.3%
![Page 8: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/8.jpg)
What if we heat?
0 10 20 30 400
50
100
150
200
250
0
3x104
6x104
9x104
1x105
I (A
)
T (K)
unsintered 400°C 700°C 800°C 900°C
jc (A/cm
2)
Treatment of 1 h in Ar
Too large Ic in low-T heated tapes quench
0 1 2 3 4 5
-400
-200
0
200
400
600°Cr
0=0.8 mm
d=100 m
M [e
mu/
cm3 ]
B [T]
5K 10K 20K 25K 30K
Magnetic measurement of MgB2 core
Assuming M=2/3 jc d
0 1 2 3 4
103
104
105
J C [A
/cm
2 ]
Magnetic Field [T]
5 K 10 K 20 K 25 K
0 10 20 30 400
50
100
150
200
250
300
0.0
3.0x104
6.0x104
9.0x104
1.2x105
1.5x105
600 Cmagnetic
700 Ctransport
400 Ctransport
I (A
)
T (K)
jc (A/cm
2)
Magnetic and transport jc coincide
![Page 9: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/9.jpg)
Argon
0 2 4 6 8 10 121
10
100
1000
4
40
400
4000
B//tape
Btape
4.2 K
jc [A/m
m2]
Crit
ical
cur
rent
[A]
Magnetic Field [T]
Anisotropy of the critical current density at 4.2 K
Correlation between magnetic and transport jc => extrapolation of 20K behavior
1.0 1.5 2.0 2.5 3.0
10
100
1000
40
400
4000
jc [A/m
m2]
Htape
Transport 4.2K
Crit
ical
cur
rent
[A]
Magnetic Field [Tesla]
Inductive 5K 10K 15K 20K 25K
New transport Ic data:27 K, s. f. > 500A 1 T ~100 A 1.5 T ~ 20 A
20K, 1.5T
4.2K, 3 T
Tape dimensions: 3.5 mm x 0.35 mmFilling factor 20%
Treated at 900°C for 2 hours in Ar
Transport properties of ex-situ tapes reacted in Argon
atmosphere
![Page 10: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/10.jpg)
0 10 20 30 40
0
3
6
9
unsintered Btape 800 C Btape 900 C Btape
unsintered B//tape 800 C B//tape 900 C B//tape
Hirr [
T]
Temperature [K]
IL of unsintered, 800ºC and 900°C tapes
10 20 30 40
0
2x10-5
4x10-5
6x10-5
Btape
R [
]
T [K]
0T 0.5T 1T 2T 3T 4T 5T 6T 8T 9T
10 20 30 40
0
2x10-5
4x10-5
6x10-5
8x10-5
B//tape
R [
]
T [K]
0T 0.5T 1T 2T 3T 4T 5T 6T 7T 8T 9T
Irreversibility lines from magnetoresistance measurements
At 800°C the initial Tc is recoveredPinning centers induced by cold working are partly removed at 900 °C
![Page 11: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/11.jpg)
Neutron diffraction experimentsILL D1A facility – Grenoble (F)
MgB2MgO
In-situ analysis of Ni-sheathed tapes confirms:a) Lattice strain increases during cold workingb) Lattice strain progressively relaxes during the heat treatment
![Page 12: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/12.jpg)
880°C
900°C
920°C
940°C
Reaction layer between Ni and MgB2
900°C
Ni
MgB2
MgB2Ni2.5
920°C
Ni
MgB2
MgB2Ni2.5
The reaction layer increases with increasing temperature
![Page 13: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/13.jpg)
880 890 900 910 920 930 9400.0
5.0x104
1.0x105
1.5x105
2.0x105
2.5x105
3.0x105
f.f. 10% f.f. 17%
5 K
j c at 1
Te
sla
Heat treatment temperature [°C]
0.0
5.0x103
1.0x104
1.5x104
2.0x104
2.5x104
f.f. 10% f.f. 17%
Magnetic jc
5 K
j c at 4
Te
sla
Optimal conditions for jc are different for low & high fields
Jc after heat treatment mainly results from the compromise between:
- MgB2 packing density
- residual lattice strain
- increase of Tc
- reaction layer with Ni sheath
![Page 14: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/14.jpg)
Critical strain
4 5 6 7 8 9 10
10
100
NIST measurementsOctober 2000
4.2 KH//tape
tape section 0.9 mm2
fill factor 16%
Cri
tica
l cu
rre
nt [
A]
Magnetic field (T)
Transport jc and critical strain measurements (NIST)
0.00 0.05 0.10 0.15 0.20 0.25 0.300
10
20
30
40
50
60
4.2K, 6T
Crit
ical
cur
rent
(A
)
Applied strain, (%)
Tape dimensions: 3.5 mm x 0.315 mmFilling factor 16%
Superconducting cross section 0.176 mm2
0.00 0.05 0.10 0.15 0.20 0.25 0.300
10
20
30
40
50
60
4.2K, 6T
n-va
lue
Applied strain, (%)
![Page 15: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/15.jpg)
First test of an MgB2 pancake
3.0 3.5 4.0 4.5 5.00
50
100
150
200
250
4.2 KC
ritic
al C
urr
en
t [A
]
Magnetic Field [T]
MgB2 pancake
BSCCO pancake
MgB2
BSCCO
Pancake coil
![Page 16: G. Grasso, A. Malagoli, M. Modica, V. Braccini, A. Tumino, S. Roncallo, E. Bellingeri, C. Ferdeghini, A.S. Siri INFM -LAMIA, Corso Perrone 24, 16152 Genova](https://reader035.vdocument.in/reader035/viewer/2022062511/55150d2b5503465e608b4a42/html5/thumbnails/16.jpg)
Ex-situ Nickel-sheathed MgB2 tapes have been fabricated by the Powder-In-Tube method in lengths up to 25 meters
Critical current densities in excess of 1000 A/mm2 have been achieved at 4.2 K and magnetic fields up to 3 Tesla
A direct correlation has been observed between MgB2 lattice strain induced by cold deformation and the irreversibility field
A relevant reaction layer between MgB2 and Nickel sheath has been observed
Conclusions