Superconducting Tl2Ba2Ca2Cu3O10 (Tl2223) was ground to powder. Mixture with silver powder (0-80% weight) and press to desired shape. After proper annealing, one can get good silver-content Tl2223 bulk superconductor. It is time-stable and has good superconducting property as same as pure Tl2223. It also has better mechanical property and far better thermal cycle property than pure Tl2223

Alzayed, N.

Fei, X.

Guo, Y.

Havenhill, A.

He, W. S.

Lucas, M. S. P.

Reichle, D.

Wong, K. K.

Xin, Y.

Ying, Z. Q.

English

NASA Technical Reports Server

Thallium 2223 High Tc Superconductor in a silver matrix
and its magnetic shielding, hermal cycle and time aging
properties
X. Fei, W.S. He, A. Havenhill,Z.Q. Ying,Y. Xin, N. Alzayed,and K.K. Wong.
Midwest SuperconductivityInc.
Y. Guo, D. Reichle, and M. S. P. Lucas
Kansas State University
ABSTRACT
Superconducting Zl2Ba2Ca2CuaOto (T12223) was ground to powder. Mixture with silver
powder (0--80% weight) and press to desired shape. After proper annealing, one can get
good silver-content T12223 bulk superconductor. It is time-stable and has good
superconducting property as same as pure T12223. It also has better mechnical property and
far better thermal cycle property than pure T12223.
I. INTRODUCTION
From pratical view, one hope bulk superconductor has good superconducting property, good
machnical preperty, time-stable, and good thermal cycle property (one cycle means rapidly
temperature change 25°c --> liquid nitrogen --> 25°c).
Unfortunately, pure T12223 does not have all above mention properties. It has good
superconducting property and it is time stable. But, its mechnical preperty is not good. It
is not easy to form it. Its thermal cycle property is bad. After a few thermal cycle, it loses
transport superconductivity.
For pratical application, need to improve its mechnical property and thermal cycle
property.
T12223superconductor in silver matrix can give better mechnical property and far better
thermal cycle property than pure T12223 and still give good superconducting property.
We have made some high Tc superconducting shielding devices using this kind of material
two years ago. By thermal cycle test and time aging test, we can say T12223with 10%--80%
weight silver is good superconducting engineering material.
II. SAMPLEPREPARATION
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https://ntrs.nasa.gov/search.jsp?R=19960000310 2020-06-16T07:02:44+00:00Z
Synthesizing Tl2Ba2Ca2Cu3010raw superconducting material
T1203(>99%), BaO2or BaO (>95%), CAO(>99%), and CUO(>99%) with the molar ratio
of cations of 2:2:2:3 are mixed and ground in an agate mortar. Then the ground powder
is pelletized in a die with a hydraulic press at an applied pressure of about 7000kg/cm2. The
pellets are then placed in a tubular alumina crucible and covered with an alumina plug.
The crucible with contents is placed in a tube furnace; The power turned on and the
temperature of the furnace raised to about 895°c at an ascending rate of 20 degrees per
minute. The samples are heated at 895°e for 50 hours and then cooled within the furnace
at a descending rate of 1 degree per minute to 600°c. Finally the furnace is turned off and
the samples cooled to room temperature within the furnace. Oxygen is flowing in the
furnace during sintering.
Fabrication of Ag-content T12223 superconducting cylinder
The pellet of raw superconducting T12Ba2Ca2Cu3010 is then broken and pulverized to a
particle size of 1-5 microns. The ground powder is then mixed uniformly with silver powder
(99.9% purity, 0.7-1.3 microns particle size) with the weight percentages of Ag:0, 10, 20, 40,
60, 80, 100. The mixed powders are then pressed into cylinders which are then annealed
in a tube furnace. Oxygen is flowing in the furnace tube during the annealing . The
temperature of the furnace is raised from room temperature to 790-820°c at a rate of 0.5 -
1 degree per minute and then maintained at this temperature for 30 hours. The furnace
temperature is then reduced at a rate of 1-2 degrees per minute to 200°c, at which point the
cylinders are then removed from the furance.
About two years ago (May--July, 92), we made several T12223 cylinder with 10%, 20%,
40%, 60% weight silver. A few months later, we made cylinder with 0%, 80%, 100% silver
for comparison.
Sample dimensions and weights as following:
SAMPLE NUMBER #1 #2 #3 #4 #5 #6 #7
SILVER CONTENT (%) 0 10 20 40 60 80 100
INNER DIAMETER (ram) 14.7 10.0 10.0 10.0 10.0 10.0 !0.0
OUTER DIAMETER 24.5 25.0 25.0 25.0 25.0 23.0 25.0
(ram)
HEIGHT (ram) 68.0 30.0 25.0 22.0 20.0 25.0 26.0
WEIGI-1T(g) 112 60 60 59 60 79 79
744
III. TEST
We use Fig.1 measurement system to measure magnetic shieding attenuation of cylinder
samples.
Then all samples underwent thermal cycle. After every 20 cycles, measure shielding
attenuation again. As the first batch of test, total 61 thermal cycles were done.
Each thermal cycle is following: Rapidly immerse sample in liquid nitrogen for about 5
minutes, take out and put in open air. So, a lot of frost first and then water condense on
surface of sample. When sample reachs room temperature again and dry, immerse it in
liquid nitrogen again. As you see, the thermal cycle is very harsh test.
After all samples were in open air for more than one and a half year, all underwent
another 50 thermal cycles, then measure shielding attenuation again.
Then, another 50 cycles thermal cycles. Now, this test is continuing.
IV. RESULT AND DISCUSSION
All test results are shown in fig. 2 - 9. At beginning, all samples are good. Magnetic
shielding attenuations are 70-90 db at f=60 Hz.
After 20 thermal cycles,pure T12223(no Ag) sample lost its magnetic shieldingproperty.
All silver-content samples are still good.
The first batch of thermal cycle test is 60 cycles. All silver-content samples are still good
after 61 cycles
In fact, when superconductor is rapidly colding and warming, it rapidly expands and
contracts. For pure T12223,all grains are hard ceramic. So, contacts between grains are
hard"to hard. When expansion and contraction, hard to hard contact produces very high
stress and it causes many microcracks inside. After several thermal cycles, there are so
many microcracks inside that all transport paths are cut off. So, there is no screen current
and lost magnetic shielding property.
When add silver into pure superconductor, silver locats between superconducting grains.
So, many contacts between grains are soft. Less microcracksare produced during thermal
cycles. So, Ag-content superductor has good thermal cycleproperty.
According to above analysis,lowAg-content sampleproduces more microcracks than high
Ag-content sample during one thermal cycle. So, if we continue to do thermal cycle test
more and more, lowAg-content sample willloss its shieldingproperty more early than high
Ag-content sample. Test result proved it.
After all samples were in open air for 1 1/2years, we did thermal cycle test again. The
second batch of test is 50 thermal cycles. After 50 cycles,measure shielding attenuation
again. Test results are:
a. 10% Ag sample was dead, lost its shielding proporty.
b. Other high Ag-content samples with Ag-content more than 10% are still good.
The results agree with above analysis. The results also mean that Ag-content T12223
superconductor is time stable.
745
V. INCREASE MAGNETIC SHIELDING EFFECT
The all Ag-eontent samples of the first batch are very short, they have lowlength diamenter
rate ( ldd see Fig. 10 ). d.
H=2Ld_innerdia. L
I_ Fig. 10. Sample's shape
D
All L/d are = 1 - 1.5
For more high magnetic shielding attenuation, need to increase critical current density
Jc of superconductor, L/d value and more thick of wall.
We have fabricated more longer cylinder:
10% Ag + 90% T12223,ID=9.7mm, OD=19.1mm, L=89mm;
20% Ag + 80% T12223,ID=9.8mm, OD=19.0mm, L=88mm.
The first one reached 132db attenuation;
The second one reached 126 db attenuation.
The effect of increasing length is shown in Fig. 11.
Inside field dependence of applied field is shown in Fig. 12.
VI. CONCLUSION
Ag-content T12223 is a good superconducting engineering material. It is time-stable and
good superconducting property as same as pure T12223. It has better mechnical property
and far better thermal cycle property than pure T12223.
References
1.J.Wang and M. Sayer, "Low frequency magnetic shielding of YBa2Cu307. :Agx high
temperature superconductors," Cryogenics 1993 Vol 33, No 12
2. Ramesh chandra, A.K. Gupta, and others, "Fabrication and characterization of High Tc
Superconducting magnetic shield," IEEE Trans. on Magn. Vol.25, No.2, 1991.
3. J.O. Wellis, M.E. Mchenry, M.P. Maley and H. Sheibrerg, "Magnetic shielding by
superconducting Y-Ba-Cu-O hollow cylinders,"IEEE Trans. on Magn. Vol.25, No.2, 1991.
746
4. H. Matsuba, A. Yahara, and D. Irisawa, "Magnetic shielding properties of HTc
Superconductor," supercond. Sci. and Teehnol. 5 (1992)
5. M. Masale, N.C. Constantinon, and D.r. Tilley "The critical field of a hollow type-II
superconducting cylinder," Supercond. Sci. and Technol. 6(1993)
6. R. Miilller, G. Fuchs, A. Grahl and A. Kohler "Magnetic shielding properties of
YBa2Cu3OT_xtubes" Supercond. Sci. and Technol. 8(1993)
Pow_I I_
Helmholtz coil Pick-up coil
coil
Fig. 1. Measurement System Diagram
747
Thallium2223 + 0% Silver
1.0 G appliedfield
120 i
100
Ihm_-_ 8ot-O= 60r-- 40
.,..,
< )
20 o
0 sample #: i
30 inner dia: 14.7 r.,._.
300 outer dia: 24.5 n_7
3000 height : 68.0 r_,
30000 weight: 112 g
Frequency
Fig.Z. Magneticfield attenuationas a function of frequencyfor Thallium 2223tube with 0% addedsilver.
The magneticfield was applied parallelto the tube axis. The graphs show measurementsmadeduring
the 1st,21st, 41st and 61st cyclesbetween roomtemper&tureand77.3 K.
Thallium2223 + 10%Silver
1.0 G appliedfield
IO0 i
8o
c 60 i
.£ ]
c 40
20 o :
0 sample #: 2
30 inner dia: I0.0 _
300 outer dia: 25.0 mm
3000 height: 30.0 mm
30000 weight: 60 g
Frequency
Fig.'5. Magneticfield attenuation as a function of frequencyfor Thallium2223tube with 10%added
silver by weight. The magnetic fieldwas applied parallelto the tube axis. The graphs show
measurementsmadeduring the 1st, 21st,41st and 61stcycles betweenroomtemperatureand77.3 K.
748
Thallium 2223 + 20% Silver
1.0G appliedfield
12o100 --=-m 80
c , t/
o
60
=D
C
40
20 o
0 sample #: 3
30 inner dia: i0,0 nc,_
300 outer dia: 25.0 =-z,) '
3000 height: 25.0 mJ_ i
30000 weight: 60 g :
Frequency ,!
q
Fig. 4. Magnetic field attenuationas a function of frequencyfor Thallium2223 tube with 20% aaded
silver by weight. The magneticfield was applied parallelto the tube axis. The graphsshow
: measurementsmadeduring the 1st,21st, 41st and 61st cyclesbetweenroomtemperatureand ~- _ K
I
L .....
Thallium 2223 + 40% Silver
1.0 G appliedfield
12o100
80
c h
o
= 60
c
40
20 o
0 sample _: 4
30 inner dia: i0.0
300 outer dia: 25.0 m_
3000 height: 22.0 mm,
30000 weight: 59 g
Frequency
Fig. 5. Magnetic field attenuationas a function of frequencyfor Thallium2223 tube with 40%added
silver by weight. The magneticfield was applied parallel to the tube axis. The graphs show
measurementsmade during the 1st,21st,41st and 61st cyclesbetweenroomtemperatureand77.3 K
749
Thallium 2223 + 60% Silver
1.0 G applied field
12o100
c
.2
N 6O
C
• 40
20 e
0 sample #: 5
30 inner dia: I0.0 _
300 outer dia: 25.0 n_:.
3000 height: 20.0 nun
30000 weight: 60 g
Frequency
Fig. 6. Magneticfield attenuationas a functionof frequencyforThallium2223 tube with 60% added
silver by weight. The magneticfield was appliedparallel to thetube axis. The graphs show
measurementsmade during the 1st,21st, 41st and61st cyclesbetweenroomtemperatureand77.3 K.
I
Thallium 2223 + 80% Silver
1.0 G applied field
12o100
.2
N 6O
c
• 40
20 o
0 sample #: 6
30 inner dia: i0.0 m_
300 outer dia: 23.0 m_,
3000 height: 25.0 mm
30000 weight: 79 g
Frequency
' Fig.7. Magneticfield attenuationas a functionof frequencyfor Thallium2223tube with80% added
silver by weight. The magneticfield was appliedparallel to thetube axis. The graphs show
measurementsmadeduring the 1st,21st,41st and 61st cycles betweenroomtemperatureand 77.3 K.
75O
100% Silver
0.5 G appliedfield
, 8o @
_'_..=C_oc._,6040 _ I h
_: 20
13
0 sample #: 7
30 inner dia: i0.0 r_7.
300 - -_°uterdia: 25.0 ,T_-
nelgnc: 26.0 mm
3000 n_mp weight: 79 g
Frequency 3000()-
Fig. 8.. Magneticlield attenuationas afunction of frequencyfor a pure silver tube. The magneticfield
was applied parallel to the tube axis. The graphs shows measurementsmadeat roomtemperature and
77.3 K.
Shielding Attenuation vs. Frequency
I00
0 ..........................................................................................................................................................................
so ........................................................................................70 _ - - =--_ ................: _ 2__.=..__
"x3
60 ............................................................................................................................................e4
= 50 ....................................................................................................................
-6 40 .........................................................................................................
"- 30 -........................................................................................................
20 _107........_. ....
10 100 1000 1E4
f(Hz)
[---1o%._g-*-20%AgI
Fig. 9. Results of test after 1 1/2 year in open air,
another 50 thermal cycles, and total 111
thermal cycles
10% Ag sample is dead and others are OK
751
At 20 G of DC Field 
120- 
T-l 
w 
" 100- 
2 
ro 
a a o -  
G 
0 60- 
.+ 
-B-> 
0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 
L (inch) 
F r e -  I I 


Thallium 2223 high T(sub c) superconductor in a silver matrix and its magnetic shielding, hermalcycle and time aging properties

Thallium 2223 high T(sub c) superconductor in a silver matrix and its magnetic shielding, hermalcycle and time aging properties

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