JPH11186024A - Oxide superconductor pseudo permanent magnet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide superconductor pseudo permanent magnet of large dimensions, capable of exhibiting superior magnetic characteristics over a wide range of magnetic field region and can be commercially stably manufactured. SOLUTION: An R-Ba-Cu-O oxide high-temperature superconductor pseudo permanent magnet is made into annular form which has a face of superconductor crystal (ab) in its axial and circumferential directions and a c-axis directed in the radial direction. The magnet can be manufactured by applying a paste of oxide high-temperature superconductor forming source material onto an annular base surface and forming an annular superconductor crystal layer by a melt growth method through the use of a seed crystal, or by forming a superconductor crystalline layer on a strip-shaped base surface in a similar method, bending it into an annulus and diffusion-jointing both ends of the ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention exhibits a high critical current density even in a high magnetic field region and a high irreversible magnetic field, and is therefore expected to function as a strong magnetic field source such as a linear motor car. R-Ba-Cu-O (R is Y, L
a, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, one or two
More than one type) oxide-based high-temperature superconductor pseudo-permanent magnet and a method for producing the same.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. Hei 7-111213
As shown in the official gazette, R-
Ba-Cu-O-based oxide high-temperature superconducting bulk material (where R is a rare earth element such as Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb) is a pinning center in the body. It is known that this can be used as a quasi-permanent magnet because it is possible to capture a magnetic field.

[0003] In this case, the strength of the magnetic field is proportional to the diameter of the bulk body. However, it is not easy at present to grow a large-sized oxide high-temperature superconducting bulk body. Therefore, at present, a columnar shape having a diameter of at most about 100 mm is at the limit of manufacture. That is, it takes a lot of time to grow an oxide high-temperature superconducting bulk body (100 mm diameter).
mm for 100 hours, 150mm for 1
This requires a growth time of as much as 50 hours), and the longer the growth time, the more the "reaction with the base material of the growth equipment" progresses, and the more the outer layer, which is more important as a magnet material, the more the properties deteriorate. .

Further, an oxide high-temperature superconductor (hereinafter, simply referred to as a high-temperature superconductor) has a large anisotropy, and therefore, as described above, in a conventional bulk magnet that can grow only in a cylindrical shape, as shown in FIG. As shown in FIG. 1, a large magnetic field could be captured only when an induced current was generated in the circumferential direction of the cylinder and a magnetic field was applied in parallel to the c-axis of the crystal. However, in this case, the critical current density and the irreversible magnetic field in the high magnetic field region are relatively small, so that the magnet can be satisfied as a pseudo permanent magnet expected to be applied to a strong magnetic field source such as a linear motor car. It has not yet been able to ensure excellent magnetic properties.

[0005] For this reason, the present inventors have proposed the method disclosed in
In order to improve the performance of a “pseudo-permanent magnet that captures and uses a magnetic field at a pinning center in a high-temperature superconductor” as described in Japanese Patent Publication No. 11213, research was conducted from various viewpoints. Then, unlike the conventional method, when a magnetic field is applied perpendicular to the c-axis of the crystal, the critical current density (especially the critical current density in a high magnetic field region) becomes very large, and the irreversible magnetic field also improves dramatically. " I came to confirm the fact.

FIG. 2 shows a high-temperature superconductor (YBa ₂ Cu).
₃ O _x ) is a graph showing the results of an investigation of “magnetic field dependence of critical current density” (when a current is passed in the direction perpendicular to the c-axis). FIG. 2 also shows the critical current of the high-temperature superconductor. The density becomes much larger in the case of applying a magnetic field perpendicular to the c-axis than in the case of applying a magnetic field parallel to the c-axis of the crystal, especially in the high magnetic field region, and the irreversible magnetic field is also significantly improved. You can see that

However, it is clear that when a magnetic field is applied perpendicularly to the c-axis of the crystal, the high-temperature superconductor pseudo-permanent magnet exhibits excellent magnetic characteristics over a wide magnetic field region as described above. When trying to capture a magnetic field in a bulk material that can be manufactured, a current must also flow in a direction parallel to the c-axis, and the critical current in this direction is essentially very small. A magnet could not be realized.

Accordingly, an object of the present invention is to provide a practical high-temperature superconductor quasi-permanent magnet which can apply a magnetic field perpendicular to the c-axis of a crystal and exhibit excellent magnetic properties over a wide magnetic field region. Put on the realization.

[0009]

Means for Solving the Problems The present inventors have conducted further studies to achieve the above object, and as a result, have obtained the following new knowledge. (a) A paste of a high-temperature superconductor forming material (such as an oxide powder of a constituent element) is applied to the surface of a ring-shaped substrate made of a metal, ceramics, or the like, and minute species of the high-temperature superconductor are applied to the paste layer. A crystal is inoculated, heated and melted to grow the crystal, whereby “c is applied in a direction perpendicular to the surface of the ring-shaped substrate (ie, in the radial direction of the ring) over the entire circumference of the ring-shaped substrate.
It is possible to form a layer of a high-temperature superconductor crystal "having its axis oriented and its ab plane oriented in the axial and circumferential directions of the ring.

(B) Since the ring-shaped high-temperature superconductor can generate an induced current in the circumferential direction by an external magnetic field, the high-temperature superconductor can apply a magnetic field perpendicular to the c-axis of the high-temperature superconductor crystal. It becomes a quasi-permanent magnet, and exhibits excellent performance that current can flow at a high critical current density and an irreversible magnetic field is large. (c) Since this ring-shaped magnet is a closed superconductor, the induced current once generated can be used as a permanent current, and a high-temperature superconductor that exhibits excellent magnetic properties over a wide magnetic field region. It can be a permanent magnet.

(D) The ring-shaped magnet body is formed by applying a paste of a high-temperature superconductor-forming raw material (such as an oxide powder of a constituent element) to the surface of a flexible belt-shaped base material. A high-temperature superconductor seed crystal is planted on the substrate and heated and melted to grow the crystal, thereby forming a high-temperature superconductor crystal layer in which the c-axis is oriented in the direction perpendicular to the surface of the strip-shaped base material. It can also be manufactured by a method in which the band-shaped substrate on which the layer is formed is rounded into a ring shape and diffusion heat treatment is performed so that the high-temperature superconductor crystal layer is bonded at both ends.

The present invention has been made on the basis of the above findings and the like, and provides the following "high-temperature superconductor pseudo permanent magnet" and "manufacturing method of high-temperature superconductor pseudo permanent magnet". . R-Ba-Cu-O (where R is Y, La, Nd, Sm, Eu,
One or two or more of Gd, Dy, Ho, Er, Tm, and Yb) is a pseudo permanent magnet used by capturing a magnetic field at a pinning center in a high-temperature superconductor based on an oxide, as shown in FIG. ,
A high-temperature superconductor pseudo permanent magnet having a ring shape, wherein the ab plane of the superconductor crystal is oriented in the axial direction and the circumferential direction of the ring, and the c-axis is oriented in the radial direction. R-Ba-Cu-O (where R is Y, La, Nd, Sm, Eu,
One or more of Gd, Dy, Ho, Er, Tm, and Yb) is a pseudo permanent magnet that is used by trapping a magnetic field at a pinning center in a high-temperature oxide superconductor. Concentrically different-diameter ring-shaped high-temperature superconductor with the ab plane of the superconductor crystal oriented in the circumferential direction and the c-axis in the radial direction of the ring ”
A high-temperature superconductor pseudo permanent magnet characterized in that it is formed in a ring shape by nesting a plurality of these as shown in FIG. A paste of an oxide high-temperature superconductor forming raw material is applied to the surface of the ring-shaped base material, and a seed crystal of the high-temperature superconductor is planted on the paste layer, and the paste layer is heated and melted to grow crystals. To form a "high-temperature superconductor crystal layer in which the ab plane of the superconductor crystal is oriented in the axial and circumferential directions of the ring and the c axis is oriented in the radial direction" on the entire peripheral surface of the paste-coated surface of the ring-shaped substrate. The method for producing a high-temperature superconductor pseudo-permanent magnet according to the above item, wherein: A paste of a raw material for forming an oxide high-temperature superconductor is applied to the surface of each ring-shaped substrate having concentric and different diameters, and a plurality of high-temperature superconductor seed crystals are planted in the paste layer, and the paste layer is heated.・ A high-temperature superconductor in which the ab plane of the superconductor crystal is oriented in the axial direction and the circumferential direction of the ring and the c-axis is oriented in the radial direction on the paste-coated surface of each ring-shaped base material by melting and growing the crystal. After the formation of the “crystal layer”, the concentric and different-diameter ring-shaped base materials having the high-temperature superconductor crystal layer are nested together, and the crystal layers are superposed so as to face each other with the crystal grain boundaries being shifted. After that, the overlapping surfaces of the crystal layers are diffusion bonded to form an integrated ring-shaped crystal layer,
The method for producing a high-temperature superconductor pseudo permanent magnet according to the above item. A paste of a material for forming an oxide high-temperature superconductor is applied to the surface of the belt-shaped base material, and a seed crystal of the high-temperature superconductor is planted in the paste layer, and the paste layer is heated and melted to grow crystals. After forming a "high-temperature superconductor crystal layer in which the c-axis is oriented perpendicular to the substrate surface" on the entire surface of the paste-coated surface of the belt-shaped substrate, the band-shaped substrate on which the high-temperature superconductor crystal layer is formed is removed. The method for producing a high-temperature superconductor pseudo permanent magnet according to the above item, wherein the permanent magnet is rounded into a ring and both ends of the crystal layer are joined by diffusion bonding. A paste of an oxide high-temperature superconductor forming material is applied to the surfaces of a plurality of strip-shaped substrates, and a plurality of high-temperature superconductor seed crystals are planted on the paste layer.
It is melted and crystal-grown to form a "high-temperature superconductor crystal layer in which the c-axis is oriented perpendicular to the substrate surface" on the paste-coated surface of the belt-shaped substrate. The high-temperature superconductor crystal layers on each strip-shaped substrate surface are superimposed on each other in a state where the crystal grain boundaries are shifted, and then the superposed surfaces are diffusion-bonded to form an integrated long crystal layer. The method for manufacturing a high-temperature superconductor pseudo permanent magnet according to the above item, wherein the material is rounded into a ring shape and both ends of the crystal layer are joined by diffusion bonding.

The ring-shaped or strip-shaped base material on which the paste of the oxide high-temperature superconductor forming material is applied may be any of metals and ceramics. It is preferable to select a material having low reactivity and not contaminating the formed high-temperature superconductor crystal layer. Needless to say, in the case of a band-shaped substrate that needs to be rolled into a ring shape after forming the high-temperature superconductor crystal layer, flexibility and moldability are also required. In addition, the paste of the oxide high-temperature superconductor forming raw material includes rare earth element oxide powder and Ba.
A paste obtained by mixing CO ₃ powder, CuO powder and the like with an organic binder and a solvent can be used. Then, as a seed crystal of the high-temperature superconductor, a crystal usually used for growing such a high-temperature superconductor single crystal may be used.

As described in the above paragraph, the high-temperature superconductor pseudo permanent magnet according to the present invention is obtained by applying a paste of a high-temperature superconductor forming raw material to the surface of a ring-shaped base made of metal or the like. -It can be manufactured by implanting a small seed crystal of a high-temperature superconductor in the strike layer and heating and melting it to grow the crystal, but at this time, by strictly controlling the melting and cooling, the single crystal ring Although it is not impossible to obtain a superconductor in a shape, the time for crystal growth treatment is shorter as the number of seed crystals to be planted is larger. Therefore, the use of a large number of seed crystals is more advantageous for industrial production. Moreover,
If the crystal growth treatment time is short, mutual diffusion with the substrate is prevented, and a high-quality high-temperature superconductor crystal can be obtained. However, when multiple seed crystals are used,
Crystals grown from adjacent seed crystals can have the same c-axis direction, but it is difficult to make the a-axis and b-axis directions uniform. Therefore, the resulting ring-shaped superconductor is a polycrystalline material as shown in FIG. Will be. In such a polycrystalline body, a problem arises in that a large current is difficult to flow due to the crystal grain boundary acting as an obstacle.

One of the problems of the present invention is to solve this problem by superimposing crystal layers in which a plurality of seed crystals are planted and grown in a state where crystal grain boundaries are shifted as shown in FIG. The problem is solved by forming a composite ring-shaped superconductor which is diffusion bonded. That is, when a plurality of seed crystals are planted and crystal grown, for example, two layers are overlapped and joined in a slightly shifted state (a state in which crystal grain boundaries are shifted).
The direction of the c-axis can be made uniform, and a smooth flow of current can be secured as shown in FIG. 6 so that a current can flow at a large critical current density in the ring-shaped superconductor. In other words, it is possible to increase the trapping magnetic field. Here, in the diffusion bonding of the high-temperature superconductor layer,
The heating temperature is about 900-1000 ° C, and the joining pressure is
It is recommended to be about 0.1 to 10 kgf / cm ² .

In the production of the high-temperature superconductor pseudo permanent magnet according to the present invention, as described in the above section, a simple band-shaped substrate can be used without using a ring-shaped substrate. In this case, first, a paste of a material for forming a high-temperature superconductor is applied to the surface of the strip-shaped base material, and a seed crystal of the high-temperature superconductor is planted. After forming a high-temperature superconductor crystal layer with the c-axis oriented in the direction perpendicular to the plane, the band-shaped substrate on which the high-temperature superconductor crystal layer is formed is rolled into a ring shape, and the high-temperature superconductor crystal layers are bonded at both ends. What is necessary is just to perform a diffusion heat treatment so that it may be performed. In the case where a plurality of seed crystals are planted and crystal-grown, as described in the above section, the high-temperature superconducting crystal layer formed on the high-temperature superconductor crystal layer is formed as described above before being rolled into a ring shape. A plurality of superconducting crystal layers may be overlapped and joined, then rounded into a ring shape and joined at both ends. By taking such measures, a ring-shaped superconductor similar to that described with reference to FIG. 6 can be obtained.

Further, in the case of manufacturing a ring-shaped superconductor having the same form as that shown in FIG. 6, adjacent high-temperature superconductor crystal grains grown on the base material surface using a seed crystal are not necessarily in close contact. It is not necessary. For example, as shown in FIG. 7, high-temperature superconductor crystal grains (high-temperature superconductor crystal layers) grown from various crystals may be separated from each other. That is,
FIG. 7 shows that a paste (R-Ba-Cu-O-based superconductor crystal growing paste) of an oxide high-temperature superconductor forming material is intermittently applied to the belt-shaped substrate surface and each paste layer is coated. Each time, a seed crystal of a high-temperature superconductor is planted, and the crystal is grown by heating and melting the crystal, thereby obtaining a band in which a superconductor crystal layer is intermittently arranged on the longitudinal surface of the band-shaped base material. The two high-temperature superconducting crystal layers are used to overlap the high-temperature superconductor crystal layers on each band-shaped substrate in such a way that the "space between adjacent high-temperature superconductor crystal layers" is shifted, and then the superposed surface is diffused 3 shows a process of forming a long crystal layer which is joined and integrated. Then, after this step, if the obtained long crystal layer is rolled into a ring shape and both ends are joined by diffusion bonding, a ring-shaped superconductor having the same performance as that shown in FIG. 6 can be realized. Becomes According to this method, a paste of an oxide high-temperature superconductor forming material (paste for growing an R-Ba-Cu-O-based superconductor crystal) and a seed crystal can be saved, or the time for growing a high-temperature superconductor crystal can be further reduced. Because the realization will come true,
It can be said that it is more advantageous industrially.

Therefore, the “grain boundary” in the present invention is defined as
Not only "boundary between adjacent crystal grains" shown in FIGS. 5 and 6, but also "adjacent crystal layer (crystal grain)" as shown in FIG.
And the interval between the two.

As described above, the method of growing the high-temperature superconductor crystal layer on the surface of the band-shaped base material and then rolling the band-shaped base material on which the high-temperature superconductor crystal layer has been formed into a ring shape also makes it possible to adjust the axial direction of the ring. Ab of high-temperature superconductor crystal in the circumferential direction
It is possible to obtain a ring-shaped high-temperature superconductor in which the surface and the c-axis are oriented in the radial direction, and this method also has an advantage that "manufacturability is easy". This becomes more remarkable as the diameter of the superconductor pseudo permanent magnet increases.

[0020]

As described above, the high-temperature superconductor pseudo-permanent magnet according to the present invention has a "ring shape, and the ab plane of the superconductor crystal extends in the axial and circumferential directions of the ring, and in the radial direction. Since the configuration is such that the c-axis is oriented, a current can be applied in the circumferential direction of the ring to apply a magnetic field perpendicular to the c-axis of the high-temperature superconductor crystal. Therefore, as described with reference to FIG. Current can flow at a high critical current density over a wide range, the irreversible magnetic field is large, and large-sized ones (for example, those having a diameter exceeding 200 mm) can be obtained relatively easily and in a relatively short time. Therefore, it is expected to function as a strong magnetic field generation source such as a linear motor car.

If a material having sufficient strength is selected as a ring-shaped or band-shaped base material for growing a ring-shaped high-temperature superconductor crystal, it can be used as it is as a reinforcing material. The problem of the strength of the permanent magnet body is also solved.

The high-temperature superconductor quasi-permanent magnet according to the present invention has an improved critical current density for capturing a magnetic field and an increased irreversible magnetic field, as compared with the conventional one, so that the maximum captured magnetic field is dramatically improved. However, if there is a concern that the characteristics may be degraded due to crystal defects or the like that tend to occur during manufacturing, as shown in the above section and FIG. 4, a plurality of concentric ring-shaped high-temperature superconductors may be used. It is preferable to form the magnet by nesting combinations (of course, the a-plane of the superconductor crystal is oriented in the c-axis in the radial direction in both the axial direction and the circumferential direction of the ring). This makes it possible to disperse the risk of characteristic deterioration due to crystal defects and the like, and to further increase the trapped magnetic field.

Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not unduly limited by these Examples.

[Embodiment 1] First, a high-temperature superconductor {Y ₂ BaCu
A YBa ₂ Cu ₃ O _x (Y123) crystal containing O ₅ (Y211)｝ forming raw material was prepared. This is Y ₂ O ₃ , BaCO ₃
And the ratio of Y: Ba: Cu is 1.8: 2.4
Mix to a mixing ratio of 3.4 and mix this mixture to 900
After calcination at 24 ° C. for 24 hours, the mixture was further heated at 1400 ° C. for 20 minutes, rapidly cooled with a copper hammer, and then finely ground using a mortar. Next, the above-mentioned pulverized mixture powder was mixed with the same amount of “isopropyl alcohol (solvent) containing 10% of polyvinyl butyral (organic binder)”.
And the resulting paste was mixed with an outer diameter of 200 mm and a width of 10 mm.
mm, 1mm thick stainless steel ring substrate "on the outer surface
It was applied in a thickness of 0.2 mm.

Then, on the applied paste, the directions of the a-axis x b-axis x c-axis are 1 mm x 1 mm x
NdBa ₂ Cu ₃ O cut out to a size of 0.1 mm
_x (Nd123) single crystal "was planted so that the c-axis direction was perpendicular to the tangent to the substrate surface (that is, the radial direction of the ring substrate), and then kept in air at 150 ° C. for 30 minutes. To evaporate the solvent isopropyl alcohol,
The binder was decomposed by holding at 0 ° C. for 30 minutes.

Subsequently, the base material on which the paste was applied was
After the temperature was raised to 0 ° C. for 1 hour, the superconducting particles were cooled and melt-grown to form a superconductor (Y123) layer all around the outer surface of the stainless steel ring base material. Thereafter, this was subjected to a heat treatment (annealing) at 500 ° C. for 100 hours in an oxygen atmosphere at 1 atm.

In the ring-shaped superconductor (Y123) thus obtained, the c-axis of the superconductor crystal is oriented in the radial direction of the ring, and the ab plane is oriented in the axial and circumferential directions of the ring. When the critical current density when a current was passed in the circumferential direction of the ring-shaped superconductor was measured by a pulse current conduction method, the critical current density was 45000 A / cm ² at 77 K and zero magnetic field. The transition was similar to the “curve in the vertical direction of the c-axis” in FIG. In addition, the irreversible magnetic field showed the same tendency as the “curve in the vertical direction of the c-axis” in FIG.

Next, in the same process, a superconductor (Y12) is formed around the entire inner surface of the stainless steel ring base (having an inner diameter slightly larger than the outer diameter of the ring base).
3) A layer-formed one is prepared, and both ring-shaped superconductor surfaces are polished and adjusted so that the surface roughness is 1 μm or less. Then, both are nested, and as shown in FIG. The superimposed bodies were heated at 950 ° C. for 10 minutes to perform diffusion bonding, and then cooled to room temperature. Then, this is then placed in an oxygen atmosphere at 1 atm.
Heat treatment (annealing) was performed for a time.

In the ring-shaped superconductor (Y123) thus obtained, the c-axis of the superconductor crystal is oriented in the radial direction of the ring in both the inner and outer layers, and the ab plane is oriented in the axial and circumferential directions of the ring. When the critical current density when a current was passed in the circumferential direction of the ring-shaped superconductor was measured by the pulse current conduction method in the same manner as described above, it was 550 at 77 K and zero magnetic field.
A 00A / cm ^2, varying the magnetic field, the critical current density was displaced in the same tendency as "curve for the c-axis perpendicular" in FIG. 2. In addition, the irreversible magnetic field showed the same tendency as the “curve in the vertical direction of the c-axis” in FIG.

Example 2 A paste of a raw material for forming a high-temperature superconductor was prepared in the same manner and under the same conditions as in Example 1, and this paste was applied to one surface of a "stainless steel strip base material 10 mm wide and 1 mm thick". It was applied on top with a thickness of 0.2 mm. The paste coating layer was intermittent in the longitudinal direction of the stainless steel strip base material as shown in FIG.

Then, as a seed crystal on the applied paste, "a-axis x b-axis x c-axis directions are each 1 mm x 1 mm x 0.
NdBa ₂ Cu ₃ O _x (Nd
123) A plurality of “single crystals” are planted so that the c-axis direction is perpendicular to the substrate surface, and the resultant is kept in air at 150 ° C. for 30 minutes to evaporate isopropyl alcohol as a solvent. The binder was decomposed by holding at 600 ° C. for 30 minutes.

Subsequently, the base material coated with the paste is heated and cooled with a temperature gradient so that the maximum temperature is 1020 ° C., so that superconducting grains are melt-grown, and one side of the stainless steel strip base material is formed. Then, a superconductor (Y123) layer as shown in FIG. 7 was formed. Then, this is added to an atmosphere of 1 atm.
Heat treatment (annealing) was performed at 00 ° C. for 100 hours.

Next, the member having the superconductor (Y123) layer formed on one side of the stainless steel strip base material in this manner is designated as No. 2.
After polishing and adjusting the surface roughness of the superconductor surface of each sheet so as to be 1 μm or less, the superconductor surfaces face each other, and the crystal layer spacing portions do not match as shown in FIG. The superposed bodies were closely adhered so as to be shifted from each other, and heated at 950 ° C. for 10 minutes while applying a pressure of 1 kfg / cm ² to the superposed bodies to perform diffusion bonding and then cooled to room temperature. Then, this was heat-treated (annealed) at 500 ° C. for 100 hours in an oxygen atmosphere at 1 atm.

Next, this laminated strip is rolled into a ring shape,
With the two end faces of the superconductor layer abutting each other, 95
Diffusion bonding by heating to 0 ° C for 10 minutes, diameter 200mm
A superconductor having a ring shape was manufactured.

In the ring-shaped superconductor (Y123) thus obtained, the c-axis of the superconductor crystal is oriented in the radial direction of the ring in both the inner and outer layers, and the ab plane is oriented in the axial and circumferential directions of the ring. When the critical current density when a current was passed in the circumferential direction of the ring-shaped superconductor was measured by the pulse current conduction method in the same manner as described above, it was 550 at 77 K and zero magnetic field.
A 00A / cm ^2, varying the magnetic field, the critical current density was displaced in the same tendency as "curve for the c-axis perpendicular" in FIG. 2. In addition, the irreversible magnetic field showed the same tendency as the “curve in the vertical direction of the c-axis” in FIG.

[Embodiment 3] Various R-Ba-Cu-O (R is Nd, La, Sm, Eu, Gd, D
A ring-shaped superconductor with a (y, Ho, Er, Tm, Yb) crystal layer was fabricated. However, when R is Nd, La, Sm or Eu, the crystal melt growth is performed in "oxygen + argon gas" having an oxygen partial pressure of 0.01 atm, and the annealing treatment after the heat treatment is performed in an oxygen atmosphere of 1 atm. A condition of 300 hours at 300 ° C. for 240 hours was adopted (other process conditions are the same). In any of the ring-shaped superconductors thus obtained, the c-axis of the superconductor crystal is oriented in the radial direction of the ring, and the ab plane is oriented in the axial direction and the circumferential direction of the ring. is there.

The critical current density of each of the obtained ring-shaped superconductors was measured in the same manner as in Example 2. At 77 K and zero magnetic field, 50,000 A / cm ² and R 20,000 for La
A / cm ^2, is that wherein R is Sm those 60000A / cm ^2, R is Eu intended 65000A / cm ^2, R is Gd 3500
0A / cm ² , 35000A / cm ² when R is Dy and R is Ho
300,000 A / cm ² for R and 300 for R for Er
00A / cm ² , and 25000A / c when R is Tm
When m ² and R were Yb, the value was 20,000 A / cm ² . Further, it was confirmed that all of them maintain a high critical current density in a wide magnetic field region and a large irreversible magnetic field, as in the "curve in the direction perpendicular to the c-axis" in FIG.

[0037]

As described above, according to the present invention, a high critical current density is exhibited in a wide magnetic field region including a high magnetic field region, an irreversible magnetic field is high, and a high magnetic field is generated by a linear motor car. Industrially extremely useful effects are brought about, such as provision of a large-sized high-temperature superconductor pseudo-permanent magnet suitable as a source or the like on an industrial scale.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a magnetic field applying method in a conventional high-temperature superconductor bulk magnet.

FIG. 2 is a graph showing the results of an investigation on “magnetic field dependence of critical current density” of a high-temperature superconductor (YBa ₂ Cu ₃ O _x ).

FIG. 3 is a diagram illustrating an example of a high-temperature superconductor pseudo permanent magnet according to the present invention.

FIG. 4 is an explanatory diagram related to another example of the high-temperature superconductor pseudo permanent magnet according to the present invention.

FIG. 5 is an explanatory diagram of a superconductor layer grown from a plurality of seed crystals.

FIG. 6 is an explanatory diagram of a state in which superconductor layers grown from a plurality of seed crystals are overlapped and joined.

FIG. 7 is an explanatory diagram relating to “an industrially more advantageous example of“ a process of forming a superconducting layer grown from a plurality of seed crystals to form a long crystal layer that is superposed and joined to be integrated ””.

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[Procedure amendment]

[Submission date] March 12, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Oxide superconductor pseudo permanent magnet and method for producing the same

Continuation of front page (71) Applicant 390023674 E. I. Dupont de Nemours and Company I. DU PONT DE NEMO URS AND COMPANY 1007 (72) Inventor Masato Murakami Masato Murakami 1-14-3 Shinonome, Koto-ku, Tokyo International Superconducting Industrial Technology Research Center-Superconducting Engineering Laboratory (72) Inventor Hiroki Ogi 19-2 Kiyohara Industrial Park, Utsunomiya City, Tochigi Prefecture, Japan Inside the Central Technical Research Institute (72) Inventor Ken Satoshi Nagashima 1-14-3 Shinonome, Koto-ku, Tokyo −Superconductivity Engineering Laboratory

Claims (6)

[Claims] (1) R-Ba-Cu-O (where R is Y, La, N
d, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb) oxide permanent magnet used in a pinning center in a high-temperature oxide superconductor to capture a magnetic field, A high-temperature superconductor pseudo permanent magnet having a ring shape, wherein the ab plane of the superconductor crystal is oriented in the axial direction and the circumferential direction of the ring, and the c-axis is oriented in the radial direction. 2. R-Ba-Cu-O (where R is Y, La, N
d, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb) oxide permanent magnet used in a pinning center in a high-temperature oxide superconductor to capture a magnetic field, A plurality of concentrically different-diameter ring-shaped high-temperature superconductors in which the ab plane of the superconductor crystal is oriented in the axial and circumferential directions of the ring and the c-axis is oriented in the radial direction of the ring are nested together. However, a high-temperature superconductor pseudo permanent magnet characterized by having a ring shape. 3. A paste of a raw material for forming an oxide high-temperature superconductor is applied to the surface of the ring-shaped substrate, and a seed crystal of the high-temperature superconductor is planted on the paste layer. A high-temperature superconductor in which the ab plane of the superconductor crystal is oriented in the axial direction and the circumferential direction of the ring and the c-axis is oriented in the radial direction on the entire surface of the paste-coated surface of the ring-shaped substrate by melting and growing the crystal. The method for producing a high-temperature superconductor pseudo-permanent magnet according to claim 1, wherein a crystal layer is formed. 4. A paste of a material for forming an oxide high-temperature superconductor is applied to the surface of each ring-shaped substrate having concentric and different diameters, and a plurality of high-temperature superconductor seed crystals are planted in the paste layer. -Heating and melting the strike layer to grow the crystal, and the surface of the paste applied to each ring-shaped substrate has "the ab plane of the superconductor crystal in the axial direction and the circumferential direction of the ring and the c axis in the radial direction. After forming an oriented high-temperature superconductor crystal layer ", concentric and different-diameter ring-shaped substrates having the high-temperature superconductor crystal layer are nested, and the crystal layers face each other in a state where crystal grain boundaries are shifted. 2. The method for manufacturing a high-temperature superconductor pseudo permanent magnet according to claim 1, wherein the superposed surfaces of the crystal layers are diffusion-bonded to form an integrated ring-shaped crystal layer. 5. A paste of a raw material for forming an oxide high-temperature superconductor is applied to the surface of the strip-shaped base material, and a seed crystal of the high-temperature superconductor is planted in the paste layer.
After melting and growing crystals to form a “high-temperature superconductor crystal layer in which the c-axis is oriented perpendicular to the substrate surface” over the entire surface of the paste-coated surface of the belt-shaped substrate, this high-temperature superconductor crystal layer is formed. The method for producing a high-temperature superconductor pseudo-permanent magnet according to claim 1, wherein the strip-shaped base material thus formed is rounded into a ring shape, and both ends of the crystal layer are joined by diffusion bonding. 6. A paste of a raw material for forming an oxide high-temperature superconductor is applied to the surface of a plurality of strip-shaped base materials, and a plurality of high-temperature superconductor seed crystals are planted on the paste layer. After heating and melting to grow the crystal, a "high-temperature superconductor crystal layer in which the c-axis is oriented perpendicular to the substrate surface" is formed on the paste-applied surface of the belt-shaped substrate. The superposed high-temperature superconductor crystal layers on each of the strip-shaped base material surfaces are superimposed on each other in a state where the crystal grain boundaries are shifted, and then the superposed surfaces are diffusion-bonded to form an integrated long crystal layer. 2. The method for producing a high-temperature superconductor pseudo permanent magnet according to claim 1, wherein the crystal layer is rounded into a ring shape, and both ends of the crystal layer are joined by diffusion bonding.