JPH0717774A - Bonding structure of oxide superconductor, bonding method and magnetic shielding material - Google Patents

Abstract

PURPOSE:To provide the bonding structure of an oxide superconductor which allows superconductive current to flow to a bonding part and does not cause the leakage of magnetic flux at the bonding part, and the method thereof and to provide the magnetic shielding material using the same. CONSTITUTION:In this bonding structure, oxide superconductors are bonded to each other by the molten solidified body of the oxide superconductor incorporated with the additive such as silver and silver oxide which reduces the peritetic temp. of the oxide superconductor expressed by the formula RE1Ba2 Cu3Cu3O7-x (RE is Y and one or >=2 kinds among rare earth elements such as Nd, Sm, Eu). The bonding free from magnetic leakage is attained for the bonding part of respective oxide superconductors, and in this way, the magnetic shielding material having large area is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding structure and a bonding method of an oxide superconducting conductor using an oxide superconducting paste, and a magnetic shield material, in which silver oxide or the like is added to lower the peritectic temperature. The present invention relates to a joining technique using an oxide superconducting paste and utilizing a low temperature partial melting phenomenon of a superconducting paste in a joining portion.

[0002]

2. Description of the Related Art Conventionally, a ferromagnetic material or a superconductor has been studied as a material for shielding a strong magnetic field generated around a superconducting magnet of a magnetic levitation train or the like. However, when it comes to achieving a highly efficient magnetic shield with a lightweight shield material, it is said that it is preferable to use the complete diamagnetism of the superconductor rather than the use of a ferromagnetic material, especially at liquid nitrogen temperature. Possible Y-Ba-Cu-O system, Bi-S
Attention has been paid to oxide superconductors such as r-Ca-Cu-O. When shielding a weak magnetic field, Bi-Sr-
Ca-Cu-O system or Bi-Pb-Sr-Ca-Cu-O
Practical application of an integrated shield container using a system oxide superconductor has started.

However, since the oxide superconductor is a type II superconductor as is well known, the lower critical magnetic field Hc ₁
In the above, it is known that the superconducting state and the normal conducting state are mixed, and the magnetic flux penetrates into the oxide superconductor to deteriorate the magnetic shield characteristics. Here, it is known that the higher the critical current density (Jc) of the superconductor, the less likely it is that magnetic flux will enter, and the better the shielding characteristics. Therefore, when shielding a strong magnetic field, it is promising to apply a Y-Ba-Cu-O-based oxide superconductor that exhibits a higher critical current density than the Bi-based superconductor in a strong magnetic field. it is conceivable that. Conventionally, Y-Ba-Cu
-O-based oxide superconductors, the QMG method (Qu-ench
and Melt Growth), MPMG method (Melt powder Melt G
rowth), PDMG method (Platinum Doped Melt Growth)
The pinning points in the oxide superconductor are finely dispersed by a melting method such as that described above, and a high critical current density is realized.

By the way, in order to actually perform a large area magnetic shield by using a Y—Ba—Cu—O type oxide superconductor, a large area shield plate is required. However, at present, a technique for producing a large-area oxide superconductor composed of a single crystal grain has not been established, and there is no effective means other than a method of combining a small-area oxide superconductor to increase the area. It is said that there is no. However, when a plurality of oxide superconductors are combined to have a large area, there is a drawback that the magnetic shield characteristics are deteriorated due to a leakage magnetic field generated from a joint portion of the oxide superconductor.

Further, even when a plurality of bulk oxide superconductors having a high critical current density are adhered to each other so that there are no gaps to have a large area, the superconducting junction is not formed at the joint portion, so that the external magnetic field is not applied. There is a problem that a shielding current that cancels out the current cannot be passed, and a leakage magnetic field is generated at the joint portion. Therefore, in order to improve the magnetic shield characteristics, superconducting bonding should be realized at the bonding portion of the oxide superconductor.

As a technique which has been conventionally studied in a method for joining superconductors, a method of mechanically crimping superconductors together, applying heat treatment, and joining by thermal diffusion (Appl. Ph.
ys. Lett. 60 (7), 898, 1992), or a joining method in which a joining portion of a superconductor is locally heated by a laser to melt (No. 2-82482).

[0007]

However, in the method of joining oxide superconductors by crimping and thermal diffusion, it is difficult to position the oxide superconductors due to the device, and a large number of oxide superconductors are joined together. When the size is increased, there is a problem that a gap is likely to be formed in the joint portion. In particular, Y showing a high critical temperature
In oxide-based superconductors such as those based on Al, Ti, Bi, etc.,
Because the coherence length is tens of angstroms,
If a gap larger than the coherence length is formed in the joint portion, the superconducting current cannot flow and the satisfactory joint cannot be achieved. In addition, the local heating method using a laser has a problem that the bonding apparatus becomes complicated, and when a plurality of oxide superconductors are stacked one above the other and bonded, there is no problem in bonding the oxide superconductors on the surface portion. Although it does not occur, there is a problem in principle that it is impossible to satisfactorily bond the oxide superconductor on the inner layer side, which is hidden by being sandwiched between the oxide superconductor on the upper layer and the oxide superconductor on the lower layer.

When manufacturing a large-area superconducting plate in a large amount, it is required that the joint be easily fixed and the heat treatment process for the joint be simple. Therefore, in order to easily fix the joining part of the superconducting plate, it is considered that the joining method using a highly viscous joining material such as paste is the most suitable, and in order to simplify the joining process, not the local heating but the uniform heating. It is considered that the heat treatment in an electric furnace having a temperature distribution is optimal.

The present invention has been made in view of the above circumstances, and a superconducting electric current can be flowed to a joint portion between oxide superconducting conductors so that a magnetic leakage can be prevented and a large-area magnetic shield material can be obtained. It is an object of the present invention to provide a joining structure, a joining method and a magnetic shield material capable of obtaining the above.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 has a composition formula RE ₁ Ba ₂ Cu ₃ O.
_7-x (where RE is Y and one or more of rare earth elements such as Nd, Sm, Eu, etc.) is added, such as silver that lowers the peritectic temperature of the oxide superconductor. The oxide superconducting conductors are joined together by a melted and solidified body of the oxide superconducting conductors containing the substance.

In order to solve the above-mentioned problems, the melted and solidified body melts and solidifies a superconducting paste comprising an oxide superconductor, an additive for lowering its peritectic temperature and a vehicle. It consists of

In order to solve the above-mentioned problems, the invention according to claim 3 is an additive such as silver which lowers the peritectic temperature of the oxide superconductor represented by the composition formula RE ₁ Ba ₂ Cu ₃ O _7-x . And the oxide superconductor and the vehicle are mixed to prepare a paste, the paste is applied between the oxide superconductors to be joined, and then the paste is partially melted at a temperature at which the oxide superconductor is melted. Is heated to a temperature at which it does not partially melt, only the paste is partially melted, and then the melt is solidified and the oxide superconducting conductors are joined by the melt solidified body.

In order to solve the above-mentioned problems, a fourth aspect of the present invention is that a plurality of plate-shaped oxide superconducting conductors are spread so as to form one layer or a plurality of layers to form a joined body. The abutting portions of the conductors are joined by the melt-solidified body according to the first aspect.

[0014]

When the oxide superconductor having a composition of RE ₁ Ba ₂ Cu ₃ O _7-x contains a specific additive such as silver or silver oxide,
The peritectic temperature is lower than that of an oxide superconductor having a composition of pure RE ₁ Ba ₂ Cu ₃ O _7-x . Utilizing this phenomenon, RE ₁ Ba ₂ C containing the above additives and having a low peritectic temperature
If an oxide superconductor having a composition of u ₃ O _7-x is used and an oxide superconductor having a peritectic temperature higher than that is joined, a temperature lower than the melting temperature of the oxide superconductor having a higher peritectic temperature is used. By heating to RE ₁ Ba ₂ C, which has a low peritectic temperature
Only the oxide superconductor having a composition of u ₃ O _7-x can be partially melted. Therefore, this partially melted RE ₁ Ba ₂
A partially solidified oxide superconducting conductor can be joined by using a melt-solidified body of an oxide superconductor having a composition of Cu ₃ O _7-x . Since the oxide superconducting conductor to be joined is not melted, the phenomenon of diffusion of an unnecessary element due to the heat treatment at the time of joining becomes difficult to occur, and the superconducting property of the oxide superconducting conductor is not deteriorated.

When the oxide superconducting conductor is joined with the above structure, since the joining portion is also an oxide superconductor, a superconducting current can be made to flow to the joining portion, and a magnetic shield which does not cause magnetic flux leakage can be obtained. realizable. In addition, since the joint portion of the oxide superconducting conductor can be composed of the oxide superconducting conductor, a large area magnetic shield without magnetic flux leakage can be obtained by combining the oxide superconducting conductors with a small area, and a strong magnetic field can be obtained. Can also provide a wide range of magnetic shields.
Further, since the magnetic shield material can be formed by using inexpensive liquid nitrogen, it can be applied to a lightweight and high-performance magnetic shield material for a magnetic levitation train or the like.

On the other hand, if the melted and solidified body for superconducting the oxide superconducting conductors is a melted and solidified product of the paste,
Since the paste can be easily applied to any part of the oxide superconducting conductor, it can be applied to joining oxide superconducting conductors having a complicated shape or superconducting joining of a minute gap between superconducting conductors.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. 1 and 2 show a magnetic shield material according to a first embodiment of the present invention. In the magnetic shield material 1 of this example, a plurality of plate-shaped oxide superconducting conductors 2 are laterally butted and joined to each other. The bonded body 3 is formed, and the bonded body 3 having a required number of layers is laminated on the bonded body 3 while being shifted by a half cycle, and bonded and integrated with each other. The joint portion between the oxide superconducting conductors 2 is the superconducting joint 2 shown in FIG.
It is joined and integrated by a.

In this example, in order to simplify the explanation,
The oxide superconducting conductor 2 of the first-layer joined body 3 is shown as a set of six pieces, and the oxide superconducting conductor 2 of the second-layer joined body 3 is shown as two sets.
Although shown as a single-piece configuration, since the size of each bonded body 3 corresponds to the area of the target magnetic shield, the number of oxide superconducting conductors 2 ... To be bonded is an appropriate number of combinations required for the magnetic shield. And

In the magnetic shield material 1 shown in FIG. 1, a superconducting joint portion 2a which is a joint portion of each oxide superconducting conductor 2 is formed.
2 is as shown in FIG. 2, but this portion is made of an oxide superconductor different from the constituent material of the oxide superconductor 2. The joint portion 2a is a melt-solidified body formed by partially melting and then solidifying a paste described later.

First, the above-mentioned oxide superconducting conductor 2 is Y-
It is a plate-like material having a composition represented by Ba-Cu-O and made of an oxide superconductor having a critical temperature higher than the liquid nitrogen temperature. In the example shown in the drawings, a plate-shaped oxide superconducting conductor 2 is used, but a bulk body of the oxide superconducting conductor or a thin or thick film is formed on a plate-shaped ceramic base material or metal base material. Needless to say, the above may be used as the oxide superconducting conductor.

The above-mentioned superconducting junction 2a is an oxide superconductor represented by the general formula RE ₁ Ba ₂ Cu ₃ O _7-x ,
Silver or silver oxide (Ag ₂ O), or silver sulfide (Ag ₂ O)
₂ S), silver nitrate (AgNO ₃ ), silver chloride (AgCl), etc. are added in the required amounts to reduce the peritectic temperature, and this is composed of a melt-solidified body. However, silver compounds except silver and silver oxide have drawbacks such as being expensive, having toxicity, and being easily decomposed by organic substances.
Silver carbonate or silver oxalate contains carbon, and Y ₁ B
Since it reacts with Ba of the oxide superconductor having the composition of a ₂ Cu ₃ O _7-x, it is not preferable for use for the purpose of the present invention. In the general formula RE ₁ Ba ₂ Cu ₃ O _7-x , RE is Y
And Nd, Sm, Eu, Er, Dy, Gd, Ho, T
Among rare earth elements such as m, Yb, and Lu, one or more kinds are shown.

Next, an oxide superconductor forming the above-mentioned superconducting junction 2a will be described below by taking an example of an oxide superconductor having a composition of Y ₁ Ba ₂ Cu ₃ O _7-x . An oxide superconductor having a so-called (123) phase composition having a composition of Y ₁ Ba ₂ Cu ₃ O _7-x is partially melted at a peritectic temperature Tp and has a composition of so-called (( ₂₎ Ba ₁ Cu ₁ O ₅ ( 211) The mixed state of the phase and the liquid phase is obtained. Therefore, the peritectic reaction represented by the following general formula occurs.

Y ₂ Ba ₁ Cu ₁ O ₅ + liquid phase → Y ₁ Ba ₂ Cu ₃ O _7-x Here, a pure Y ₁ Ba ₂ Cu ₃ O _7-x composition superconductor has silver, silver oxide or the like. Of the peritectic temperature T
p can be lowered, and the one in which the additive is added is
It is possible to partially melt the superconductor having a pure Y ₁ Ba ₂ Cu ₃ O _7-x composition below the peritectic temperature (about 1000 ° C.), for example, 968 to 983 ° C. Utilizing this phenomenon,
Using the partially melted oxide superconductor, the unmelted oxide superconductor 2 can be joined.

That is, a paste in which the powder of the oxide superconductor and the powder of the additive are dispersed in a vehicle is prepared, and the paste is applied to the abutting portion of the oxide superconductors 2, and then the whole paste is applied. Is not less than the peritectic temperature of the pure oxide superconducting conductor 2 and is heated to a temperature lower than the peritectic temperature of the pure oxide superconducting conductor 2 so that only the paste is partially melted and then solidified. The oxide superconducting conductor 2 can be joined. The vehicle is appropriately selected from known organic vehicles such as liquid paraffin, butyl carbitol acetate (BCA), toluene, ethyl cellulose, terpineol, dibutyl phthalate, isopropyl alcohol, polyvinyl butyral in ethanol, cyclohexane and octyl alcohol. You can select and use it.

Here, when Ag ₂ O is used as an additive to be contained in the superconducting junction 2a, if the amount of addition of Ag becomes too large, Ag is partially melted in the surrounding oxide superconducting conductor 2 side. There is a risk of diffusion and deterioration of the superconducting properties of the oxide superconducting conductor 2. Further, if the amount of addition of Ag is too large, Ag is diffused to the surrounding oxide superconducting conductor 2 side during partial melting and the peritectic temperature of the oxide superconducting conductor 2 is lowered, so that part of the oxide superconducting conductor 2 is This may cause partial melting. Therefore, when Ag is contained in the superconducting junction 2a formed by partial melting, the content is preferably 20% by weight or less.

Next, the inventors of the present invention added Ag ₂ O to Y ₁ Ba ₂
The rate of decrease in peritectic temperature when added to an oxide superconductor having a composition of Cu ₃ O _7-x was measured. The results are shown in Table 1 below.
Shown in. (Hereafter, margin)

[0027]

[Table 1] As is clear from the results shown in Table 1, 1% by weight or more of A
It was revealed that the peritectic temperature can be lowered by incorporating g ₂ O into the superconductor having the composition of Y ₁ Ba ₂ Cu ₃ O _7-x . Moreover, the peritectic temperature is about 97 by adding more than 5% by weight.
Stable at 0 ° C, T of pure (123) phase at 5 wt% or less
It was found that the p peak remained weak. Furthermore, the addition amount is 20
If the content exceeds 5% by weight, the effect of lowering the peritectic temperature is not improved, the proportion of the non-superconducting phase is increased, and the diffusion amount of silver in the bulk is also increased. Therefore, 20% by weight or less is preferable. The optimum amount of silver added is about 10% by weight, considering that the silver particles do not become coarse during partial melting and do not diffuse to the surrounding oxide superconducting conductor.

Furthermore, as described above, the oxide superconducting conductor 2
If a paste is applied between the two and the paste is melted and solidified and then oxygen-annealed, it is possible to improve the superconducting properties by introducing oxygen into a region where oxygen is insufficient in the 123-phase oxide superconductor. it can.

As described above, since the magnetic shield material 1 of the present invention uses the superconducting joint portion 2a at the joint portion between the oxide superconducting conductors 2, the superconducting current can flow in the joint portion. It is possible to provide the magnetic shield material 1 in which magnetic leakage does not occur. Therefore, there is a feature that magnetic shielding can be performed more efficiently than before. Furthermore, if the oxide superconducting conductor 2 is joined with the above-mentioned structure, since the joining portion is also an oxide superconductor, a superconducting current can be flowed to the joining portion, and a magnetic shield without magnetic flux leakage is realized. it can. Further, since the joint portion of the oxide superconducting conductor 2 can be formed of a superconductor, a large-area magnetic shield without magnetic flux leakage can be easily obtained by combining the superconducting conductors 2 having a small area, and a strong magnetic field can be obtained. Also has a wide range of magnetic shields. Further, since the large-area magnetic shield material 1 can be used by using inexpensive liquid nitrogen, a wide range of lightweight and high-performance magnetic shield can be provided for a magnetic levitation train or the like.

On the other hand, if the melt-solidified body for superconducting the oxide superconducting conductors 2 is a melt of the paste, the paste can be easily applied to any part of the oxide superconducting conductor. The present invention can also be applied to the joining of oxide superconducting conductors, or the joining of minute gaps between superconducting conductors. Therefore, for example, in the case where a joint failure part has been generated for some reason in the joint part of the oxide superconducting conductors that have already been joined, the paste is applied and then partially melted to repair this joint failure part. Can be performed.

FIG. 2 shows a second magnetic shield material according to the present invention.
1 shows an example, and the magnetic shield material 1'of this example
Is an example in which only one layer of the bonded body 3 of the magnetic shield material 1 shown in FIG. 1 is used, and even in the structure of this example, a magnetic shield without magnetic leakage is possible as in the previous example. In addition,
In the two-layer structure of the example shown in FIG. 1 described above, or in the one-layer structure of this example, when the superconducting conductor 2 alone may cause mechanical strength shortage, the superconducting conductor 1 or the superconducting conductor 1 May be integrated with a substrate or base material made of a metal material or ceramic. Thereby, the required mechanical strength can be secured.

"Production Example" First, a superconducting paste was prepared. Y ₂ O ₃ , BaCO ₃ , and CuO powders were added to Y: B.
Mixing was carried out so that the molar ratio of a: Cu was 1: 2: 3 to obtain a mixed powder. Then, this mixed powder is heated in air at 920 ° C. for 12 hours to cause a solid phase reaction, and Y ₁ Ba ₂ C
A superconducting powder having a composition of u ₃ O _7-x was obtained, and a powder of Ag ₂ O was mixed with the superconducting powder so as to have an addition ratio of 10% by weight to obtain a raw material powder. This addition amount is intended to prevent the added Ag from diffusing to the side of the superconducting conductor to be joined and lowering the peritectic temperature of the superconducting conductor, and the silver particles of the non-superconducting phase are coarse when partially melted. Since it is set for the purpose of preventing the formation of silver, it is preferable that the addition amount of silver is set to a necessary minimum.

Next, the raw material powder and liquid paraffin were mixed at a weight ratio of 10: 1 to prepare a superconducting paste. In addition, as a comparative example, a superconducting paste prepared by adding 50% by weight of Ag ₂ O was also prepared. Then, using each of the above-mentioned pastes, Y ₁ Ba ₂ Cu produced by a melting method
An oxide superconducting conductor having a composition of ₃ O _7-x was joined. FIG. 4 shows the joined state. The oxide superconducting conductor 10 used in this example is a rectangular parallelepiped having a width of 1.5 mm, a height of 1.0 mm, and a length of 10 mm.
In each case, the orientated Y-based oxide superconductor crystal is oriented in the height direction with the c-axis oriented. Then, these end portions are overlapped with each other via a superconducting paste, and the overlapped portions are heat-treated under the conditions shown in FIG.

First, the liquid paraffin in the superconducting paste is decomposed and evaporated by heating at 300 to 500 ° C., and then Y
_After maintaining for 1 hour at 990 ° C, which is lower than the peritectic temperature of the pure oxide superconductor of ₁ Ba ₂ Cu ₃ O _7-x composition, the superconducting paste was partially melted and then cooled to 970 ° C over 5 minutes. ,
Subsequently, it is cooled to 970 to 940 ° C. at a rate of 3 ° C./hour to grow a crystal of a superconductor having a composition of Y ₁ Ba ₂ Cu ₃ O _7-x , and subsequently cooled to room temperature to solidify the melt and oxidize it. The superconductors 10 and 10 were joined. Furthermore, 600 ° C to 400
12 hours while gradually cooling to 0 ° C in an oxygen atmosphere
It was heated for an hour, then heated at 400 ° C. for 8 hours in an oxygen atmosphere, and then cooled to room temperature to complete the joining.

In order to confirm the current transport characteristics at the joints of the oxide superconducting conductors 10 and 10 joined as described above, the 4-terminal method by applying a DC pulse current was used.
The critical current density Jc was measured at K and an external magnetic field of 0T. The results are shown in Table 2 below. The 4-terminal method is
The current measurement leads were connected to points A and E of FIG. 4, and the voltage measurement lead wires were connected to points B and D.

[0036]

[Table 2]

As is clear from the results shown in Table 2, Ag
_In the sample to which 10% by weight of ₂ O was added, Jc = 8.4 ×
It was 10 ² A / cm ^2, and it was possible to confirm that the joint portion was superconducting.

[0038]

As described above, the junction structure of the present invention has a structure when a superconductor having a composition of RE ₁ Ba ₂ Cu ₃ O _7-x contains a specific additive such as silver or silver oxide. The peritectic temperature is higher than that of RE ₁ Ba ₂ Cu ₃ O _7-x having a low peritectic temperature by using the phenomenon that the crystal temperature lowers. Since the structure in which the oxide superconducting conductors are joined is adopted, by heating to a temperature lower than the melting temperature of the oxide superconducting conductor having a high peritectic temperature, RE ₁ Ba ₂ Cu ₃ O _{7-x having} a low peritectic temperature is obtained. Only the superconductor of the composition can be partially melted, and this allows the partially solidified oxide of the RE ₁ Ba ₂ Cu ₃ O _7-x composition to be used for the non-molten oxidation. The superconducting conductors are joined. Further, since the oxide superconducting conductor to be joined is not melted at the time of joining, the superconducting property of the oxide superconducting conductor is not deteriorated by the heat treatment at the time of joining.

Further, if the oxide superconducting conductor is joined with the above structure, since the joining portion is also an oxide superconductor, a superconducting current can be flown to the joining portion and a magnetic shield which does not cause magnetic flux leakage. Can be realized. Further, since the joint portion of the oxide superconducting conductor can be configured by the oxide superconducting conductor, a large area magnetic shield without magnetic flux leakage can be obtained by combining the oxide superconducting conductors having a small area.
Magnetic shielding can be performed in a wide range even in a strong magnetic field. Further, since the magnetic shield material can be used by using inexpensive liquid nitrogen, it is possible to provide a lightweight and wide-range high performance magnetic shield material for a magnetic levitation train or the like.

On the other hand, when the melt-solidified body for superconducting the oxide superconducting conductors to be superconducting is a melt of the paste, the paste can be easily applied to any part of the oxide superconducting conductor. The present invention can also be applied to the joining of oxide superconducting conductors, or the joining of minute gaps between superconducting conductors. Therefore, for example, in the case where a defective joint portion has been generated due to some cause in the joint portion between the oxide superconducting conductors that have already been joined, by applying a paste and then partially melting and solidifying the paste,
It is possible to obtain excellent effects such as repairing the defective joint portion.

Since the oxide superconducting conductor and the whole joint portion thereof are collectively heated and solidified to form superconducting joint, an expensive device required for local heating by a laser is unnecessary and is generally used. There is a feature that they can be joined by using a heating device and can be easily implemented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a partial structure of a magnetic shield material formed by stacking small-area plate-shaped oxide superconductors with an upper layer and a lower layer being staggered and bonded to each other. .

FIG. 2 is an enlarged view showing a joint portion of the magnetic shield material shown in FIG.

FIG. 3 is a perspective view showing another structural example of the magnetic shield material.

FIG. 4 is a perspective view showing a joined state of a test example in which rod-shaped oxide superconductors are joined together.

FIG. 5 is a diagram showing heat treatment conditions used in test examples.

[Explanation of symbols]

 1, 1'magnetic shield material, 2 oxide superconducting conductor, 2a superconducting joint, 3 joined body, 10 oxide superconducting conductor,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01F 1/00 H01R 4/68 ZAA 7250-5E H05K 9/00 ZAA WH (72) Inventor Ohno Kaoru 2-8-8, Hikarimachi, Kokubunji, Tokyo 38 Inside the Railway Technical Research Institute

Claims (4)

[Claims] 1. A composition formula of RE ₁ Ba ₂ Cu ₃ O _7-x (where R is
E is 1 of Y and rare earth elements such as Nd, Sm and Eu.
Or a mixture of two or more of the oxide superconducting conductors, which contains an additive such as silver or silver oxide, which lowers the peritectic temperature of the oxide superconducting compound, A bonded structure of an oxide superconducting conductor characterized by being bonded. 2. The melt-solidified body is obtained by melting and solidifying a superconducting paste comprising an oxide superconductor, an additive for lowering the peritectic temperature of the oxide superconductor, and a vehicle. Structure of the oxide superconducting conductor of. 3. The composition formula RE ₁ Ba ₂ Cu ₃ O _7-x (where R is
E is 1 of Y and rare earth elements such as Nd, Sm and Eu.
A mixture of the above oxide superconductor and vehicle is mixed with an additive such as silver or silver oxide which lowers the peritectic temperature of the oxide superconductor represented by the formula 1 or 2 or more). , Is applied between oxide superconducting conductors to be joined, and is then heated to a temperature at which the paste is partially melted and at which the oxide superconducting conductor is not partially melted, and only the paste is partially melted, and then melted. A method for joining oxide superconducting conductors, characterized in that the bodies are solidified and the oxide superconducting conductors are joined together by a melted solidified body. 4. The fusion product according to claim 1, wherein a plurality of plate-shaped oxide superconducting conductors are spread so as to form one layer or a plurality of layers to form a joined body, and the abutting portions of the oxide superconducting conductors are joined to each other. A magnetic shield material characterized by being joined by a solidified body.