JP2002265221A - Oxide superconductor single crystal grain aggregate, target material and production process of the same target material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide superconductor target material 10 capable of stabilizing the mount of a scattered raw material in a thin film production process by an ion- beam-assisted vapor deposition method or sputtering method and also to provide a production process of the target material 10. SOLUTION: The formation process of an oxide superconductor 20 which consists of this oxide superconductor single crystal grain aggregate and has a >=95% relative density and in which each of the single crystal grains has a >=0.5 mm grain size and is oriented along the c-axis having a <=5 deg. inclination in relation to the c-axis of any of the other single crystal grains, comprises using a substrate containing another oxide superconductor having a higher melting point than that of the objective oxide superconductor 20 to be formed, as a prepared substrate 30, bringing the prepared substrate 30 into contact with the surface of a melt of a raw material for the oxide superconductor 20 and pulling the substrate 30 from the melt, to form the objective oxide superconductor single crystal grains 1, 2, 3, 4, or the like, on the surface of the substrate 30, wherein, when this target material 10 is produced by using the oxide superconductor 20, the amount of a scattered raw material can be stabilized in a thin film production process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconductor having a high density and uniform orientation, a method for producing the same, and a target material produced from the oxide superconductor.

[0002]

2. Description of the Related Art Conventionally, in order to produce a thin oxide superconductor thin film for drawing a practical oxide superconducting long wire, CVD has been used.
Method, a laser deposition method, a reactive deposition method, a sputtering method, and the like are used. Among them, in the sputtering method and the laser vapor deposition method, ions or laser light is irradiated to a target material to strike out atoms or molecules constituting the target material, thereby forming a thin film on a desired substrate. Since the oxide superconductor used as the target material is required to have a size of at least 20 mm square or more or 20 mmφ or more, it is generally manufactured by a sintering method or a hot press firing method.

[0003] Here, the sintering method refers to calcining a powder of an oxide or an oxide-forming compound (carbonate, nitrate, etc.) of a constituent element of an oxide superconductor and then adding a molding binder. It is a method of molding and sintering. The hot press firing method is a method in which a powder or a compact of the above-mentioned constituent element is put in a mold and fired at high temperature and high pressure.

[0004]

However, it has been found by the present inventors that the above-mentioned prior art has the following problems. That is, in the sintering method, the addition of a binder is indispensable in order to improve the moldability of the molded body, but since the binder is decomposed during sintering,
The decomposition gas may cause cracks or warpage in the sintered body after sintering.

[0005] On the other hand, in the hot press firing method, carbon may be melted from a carbon mold used in pressing and may be mixed as an impurity into a compact after sintering. In addition, as a common problem of the sintering method and the hot press firing method, when a thin film is manufactured using the manufactured target material, the scattering amount of the raw material is not stable, so that the thickness of the obtained thin film becomes uneven. As a result, the superconducting characteristics and the like sometimes become non-uniform.

Here, as a solution to these problems,
It is conceivable to use a single crystal of an oxide superconductor as a target material. However, since the single crystal requires a great deal of time to grow the crystal, a reaction between the raw material melt and the crucible causes a composition deviation of the raw material melt. Therefore, the single crystal has not been grown to a required size as a target material.

[0007] The present invention has been made under the above-mentioned background, and since no binder or mold is used, there is no warpage or cracking, the impurity concentration is low, and the relative density is high. Oxide superconductors that have reached practical levels in terms of workability and cost, and oxide superconductors made from this oxide superconductor that can stabilize the amount of material scattered during sputtering. An object of the present invention is to provide a target material and a method for manufacturing the same.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and as a result, have found that an oxide superconductor used as a target material for forming a thin film having good superconducting properties. The requirements to be fulfilled became clear. 1. If the molded product of the oxide superconductor has cracks or warpage, the target material cannot be manufactured. Therefore, it is preferable not to use a binder in the manufacturing process of the molded article. 2. If impurities are mixed in the oxide superconductor compact, the characteristics of the formed superconducting thin film are not stable. Therefore, it is preferable not to use a mold or the like under high temperature and high pressure. 3. In film formation using the target material, in order to stabilize the scattering amount of the raw material, in the oxide superconductor constituting the target material, the crystal grain size is increased to 0.5 mm or more, and the overall theoretical density is increased. It is preferable that the relative density when it is 100% is 95% or more. Furthermore, in each crystal grain, the mutual a-axis or the b-axis forms an angle of 90 ° ± 5 ° or 180 ° ± 5 °, and the inclination of the mutual c-axis is oriented at 5 ° or less. Is preferred. 4. As a size that can be used as a target material, it is preferable that an oxide superconductor having a size of at least 20 mm square or more or 20 mm φ or more, preferably 50 mm square or 50 mm φ or more can be manufactured with good workability and low cost.

In order to satisfy the requirements of the above items 1 to 3, it is not a method of adding a binder to the powder of the constituent elements and sintering, or a method of hot pressing in a mold, but melting the powder of the constituent elements at a high temperature. A preferred method is to pull the oxide superconductor from this melt. However, if a step of pulling the single crystal body is adopted here, a large amount of time is required for crystal growth as described above, and a crystal having a required area cannot be obtained. Can not meet the requirements.

[0010] Here, as a result of repeated trial and error, the present inventors have come up with a revolutionary method of pulling up an oxide superconductor. That is, a thin film, a thick film, or a c-axis oriented oxide superconductor that has a higher melting point than the intended oxide superconductor and does not melt even when in contact with the target oxide superconductor melt. A melt of an oxide superconductor having a melting point equal to or higher than the oxide superconductor to be manufactured, which had a size equal to or higher than the desired oxide superconductor, was prepared as a substrate. Next, when the substrate was brought into contact with the surface of the melt and then pulled up, a target aggregate of single crystal particles of the oxide superconductor could be formed on the substrate. The obtained aggregate of single crystal particles of the oxide superconductor thus obtained was processed into a target material. As a result, it was found that all of the above requirements 1 to 4 were satisfied, and the present invention was completed.

That is, a first invention for solving the above-mentioned problem is an aggregate of oxide superconductor single crystal particles, which has a relative density of 95% or more, and has a relative density of 95% or more. The particle diameter of the particles is 0.5 mm or more, the oxide superconductor single crystal particles, the mutual a-axis or b-axis, 90 °
The angle is ± 5 ° or 180 ° ± 5 °, and the mutual c-axis tilt angles are less than or equal to 5 °.
An aggregate of single crystal oxide superconductor particles having a size usable as a target material.

According to a second aspect of the present invention, there is provided an aggregate of oxide superconductor single-crystal particles grown from the surface of any of a thin film, a thick film and a melt of a c-axis oriented oxide superconductor having a desired area. Wherein the oxide superconductor single crystal particles have a relative density of 95% or more, the particle size of the oxide superconductor single crystal particles is 0.5 mm or more, the oxide superconductor single crystal particles An oxide superconductor having a size that can be used as an oxide superconductor.

According to a second aspect of the present invention, there is provided an aggregate of oxide superconductor single crystal particles of a c-axis-oriented oxide superconductor having a desired area and grown from a surface of any of a thin film, a thick film and a melt. Having a relative density of 95% or more, a particle size of the oxide superconductor single crystal particles is 0.5 mm or more, and a mutual c
An aggregate of single crystal oxide superconductor particles, characterized in that the axes are oriented so that the inclination angle is 5 ° or less.

According to a third aspect of the present invention, there is provided a target material produced from the aggregate of the oxide superconductor single crystal particles according to the first or second aspect.

According to a fourth aspect of the present invention, there is provided a substrate including an oxide superconductor having a higher melting point than the oxide superconductor constituting the aggregate of the oxide superconductor single crystal particles according to the first or second aspect. Then, after bringing the surface of the substrate into contact with the surface of the appropriately prepared raw material melt, the aggregate of the oxide superconductor single-crystal particles according to the first aspect of the present invention is applied to the surface of the substrate by pulling up. And a method for producing an aggregate of oxide superconductor single crystal particles.

According to a fifth aspect of the present invention, there is provided an aggregate of single crystal particles of an oxide superconductor according to the fourth aspect, wherein the substrate is formed by depositing an oxide superconductor on a ceramic substrate. It is a manufacturing method of.

According to a sixth aspect of the invention, as the substrate, the ceramic substrate has a higher melting point than the oxide superconductor constituting the aggregate of the oxide superconductor single crystal particles according to the first or second aspect. The method for producing an aggregate of single crystal particles of an oxide superconductor according to the fourth invention, characterized in that an oxide superconductor formed into a film is used.

The seventh invention relates to a REB manufactured by a melting method.
After using the aCuO-based material as a substrate and bringing the surface of the substrate into contact with the surface of a suitably prepared raw material melt,
A method for producing an oxide superconductor, comprising forming oxide superconductor single crystal particles on the surface of the substrate by pulling up the substrate.

According to an eighth aspect of the present invention, the surface of the substrate is brought into contact with the surface of a suitably prepared raw material melt and then pulled up from the melt to the substrate at a temperature of 1 to 100 ° C./cm.
The method for producing an aggregate of single crystal oxide superconductor particles according to any one of the fourth to seventh inventions, wherein a temperature gradient is provided.

A ninth aspect of the present invention is the method according to any one of the fourth to eighth aspects, wherein, when preparing the raw material melt, a crucible made of the same element as the raw material element to be melted is used. This is a method for producing an aggregate of oxide superconductor single crystal particles.

According to a tenth aspect, there is provided an oxide superconductor thin film formed by using the target material according to the third aspect.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is an external perspective view of an oxide superconductor target material manufactured in Example 2 described later. In FIG. 1, an oxide superconductor target material 10 is a single crystal 1 of an oxide superconductor,
The aggregate 20 of 2, 3, 4,... Is grown on a prepared molded body 30 described later and then molded. First,
The prepared molded body 30 will be described. The prepared molded body 30 has a melting point higher than that of the oxide superconductor single-crystal aggregate 20 to be produced, and comes into contact with the melt of the oxide superconductor single-crystal aggregate 20. Refers to a molded product of an oxide superconductor having a composition that does not melt and has a size equal to or larger than the finally desired oxide superconductor. As the prepared molded body 30, a ceramic substrate (MgO, YSZ, (LaAlO ₃ ) _0.3 − (SrAl
_0.5 Ta _0.5 O ₃ ) _0.7 , Y ₂ O ₃ , SrTiO ₃ , LaAl
O ₃ , YAlO ₃ , LaSrAlO ₄ , NdCaAlO ₄ ,
NdGaO ₃ , LaGaO ₃ , LaSrGaO _4, etc.) and an oxide superconductor formed by sputtering, laser vapor deposition, paste, organic acid salt, etc., and then sintered as required. A ceramic substrate with a superconductor film can be used. REB manufactured by the melting method
A c-axis oriented plane of an aCuO-based material can also be used.
In this case, since the growing crystal also has improved c-axis alignment,
This is a preferred embodiment in that the pulling speed can be increased, and a material having a melting point equivalent to the melt of the single crystal aggregate 20 of the oxide superconductor can be used. RE is a rare earth element containing Y.

After the prepared compact 30 is brought into contact with the surface of the melt, it is pulled up. At this time, the temperature gradient from the prepared compact 30 to the melt is 1 to 100 ° C.
/ Cm is preferable in that the film formation rate can be increased. Further, the lifting speed at this time is 0.05 to 10 m.
m / hr is preferable in order to maintain the uniformity of the pulled oxide superconductor. At the time of this pulling, it is preferable to pull up while rotating the prepared compact 30 at 1 to 300 rpm in order to maintain the uniformity of the oxide superconductor to be pulled up.

When the melt is prepared, a crucible made of the same element as that contained in the melt may be used as a crucible material in order to prevent impurities from entering the melt from the crucible. preferable. As the rare earth element in the oxide superconductor target material produced by this pulling method, any rare earth element or a mixture thereof can be used, but any of Nd, Sm, Gd, or a mixture thereof is used. When a rare earth element is selected so as to contain 50 at% or more, the critical current density of a superconducting wire manufactured using this oxide superconductor target material in a high magnetic field can be increased.

By the above operation, 0.5-0.5 of the pulled oxide superconductor is placed on the prepared compact 30.
An aggregate 20 of 10 mm single crystal bodies 1, 2, 3, 4,... Was obtained. (Hereinafter referred to as “single crystal aggregate 20”.) When this single crystal aggregate 20 was analyzed by XRD, c-axis orientation was found on the prepared molded body 30,
In addition, no growth of liquid phase components showing no superconductivity was observed. In each single crystal grain, the a-axis or the b-axis forms an angle of 90 ° ± 5 ° or 180 ° ± 5 °, so that the density of the single crystal aggregate 20 is almost completely filled with oxygen. The theoretical density of the oxide superconductor in the
When the relative density was set to 0%, the relative density was 95% or more. On the other hand, in the single crystal aggregate 20, c
The axis was oriented at an inclination angle of 5 ° or less.

Next, the single crystal aggregate 20 and the prepared compact 30 were formed into an oxide superconductor target material 1, and an oxide superconducting thin film was formed by sputtering and laser vapor deposition. However, the scattering amount of the raw material was stable. Further, the obtained oxide superconducting thin film had a uniform thickness and no impurities were found.

(Example 1) BaC of 3N purity as a raw material
The powders of uO ₂ and Y ₂ BaCuO ₅ are mixed in a molar ratio of Y: Ba:
Weigh and mix so that Cu = 4: 36: 60, and load into a crucible. A crucible made of Y ₂ O ₃ was used.
After the temperature was raised to 70 ° C. to melt the raw material powder, a temperature gradient of 8 ° C./cm was added up and down so that the upper part of the crucible was on the low temperature side,
The temperature was lowered until the upper part of the melt in the crucible reached 1000 ° C.

On the other hand, using a MgO substrate 25mm square as a substrate material that has been prepared, YBa ₂ Cu ₃ O ₇ higher melting point than the oxide superconductor SmBa ₂ Cu ₃ O _7-X on its surface, Nd
A paste agent such as Ba ₂ Cu ₃ O _{7 -X} , GdBa ₂ Cu ₃ O _{7 -X} , etc. was spray applied, and then fired at 1020 ° C. for 10 hours. After the prepared substrate material is brought into contact with the melt, the substrate material is pulled up to about 4 mm under the conditions of a pulling speed of 0.5 mm / hr and a rotation speed of 100 rpm, and then the pulling speed is set to 10 mm / hr. Separation from the liquid was performed. As a result, the prepared 25
The thickness is about 4 mm and the height and width are 0.
6-4mm square, mutual a-axis or b-axis is 90 ° ± 5 °
Alternatively, a single crystal aggregate in which Y ₁ Ba ₂ Cu ₃ O _x single crystals are arranged at an angle of 180 ° ± 5 ° and the mutual c-axis tilt angle is 5 ° or less was obtained. When the density of this single crystal aggregate was measured, it was 6.23 g / cm ³ . This corresponds to about 98% in relative density when the theoretical density is 6.34 g / cm ³ .

When the obtained single crystal aggregate was analyzed by XRD, it was found to be c-axis oriented such that the direction perpendicular to the prepared substrate surface was the c-axis. Further, when the composition was analyzed by ICP, the molar ratio of Y: Ba: Cu =
1.01: 2.02: 2.97, and it was confirmed that no impurities were contained.

Four single-crystal aggregates were prepared, arranged and polished, and processed into an oxide superconductor target material. And Y
On a Hastelloy tape on which an SZ alignment film was formed as an intermediate layer, Y ₁ Ba ₂ Cu was deposited by an ion beam assisted vapor deposition method.
_{When the 3} O _x superconducting thin film was formed over 1 m, the scattering amount of the raw material was stable for a long time in the target material using any of the paste materials in producing the prepared substrate material. . Further, the obtained superconducting thin film had a substantially uniform thickness and no impurity was found.

The superconducting thin film thus obtained was subjected to XR
When analyzed by D, Y₁Ba_TwoCu _ThreeO_x(00n)
An orientation peak was observed. 1m tape produced
Current terminals at both ends of the
Density measured by 4-terminal method, no external magnetic field
At 5 × 10^FiveA / cm^Two1 × 10 in external magnetic field 2T^FiveA
/ Cm^TwoLong and high critical current density characteristics
I got it. This is because the amount of raw material scattered was stable
Is considered to be an effect.

(Example 2) In the same manner as in Example 1, Y ₂ O ₃
A melt having a composition of Y: Ba: Cu = 4: 36: 60 is prepared in a crucible. On the other hand, the production of the substrate material was performed as follows. First, each raw material powder of bY ₂ O ₃ , BaCO ₃ , and CuO is weighed so that Y: Ba: Cu = 1.8: 2.4: 3.4, and then only BaCO ₃ and CuO are mixed at 880 ° C. 3
By calcining for 0 hour, a calcined powder of BaCuO ₂ and CuO was obtained.
(The molar ratio is BaCuO ₂ : CuO = 2.4: 1.0.)

Next, the calcined powder, the weighed Y ₂ O _3, and a 0.5 wt% Pt powder (average particle size 0.01
μm) and calcined at 900 ° C. in the air for 10 hours to obtain a calcined powder. The calcined powder was pulverized with a raikai machine to obtain a synthetic powder having an average particle size of about 2 μm. The synthetic powder thus produced was press-molded into a disk having an outer diameter of 53 mm and a thickness of 27 mm to prepare a precursor.

This precursor was placed on an alumina substrate on which Y ₂ O ₃ powder was spread, and was placed in a two-zone furnace. Then, the temperature in the furnace is raised from the room temperature to 1100 ° C. in 50 hours, and then maintained for 20 minutes to bring the precursor into a semi-molten state. To 5
A temperature gradient of 100 ° C./cm was applied and the top temperature of the precursor was 100
The temperature was lowered at 10 ° C./min until the temperature reached 5 ° C. Here, a seed crystal having a composition of Nd _1.8 Ba _2.4 Cu _3.4 O _x prepared in advance by a melting method is brought into contact with the upper part of the precursor so that the growth direction is parallel to the c-axis. Was cooled from 1005 ° C. to 995 ° C. at a rate of 0.5 ° C./hr.
The temperature was maintained for 0 hour, and then gradually cooled to 925 ° C. over 70 hours. Next, the temperature of the upper part of the precursor was 925 ° C.
In this state, the lower part of the precursor was cooled such that the temperature gradient between the upper and lower parts of the precursor was 0 ° C./cm, and the precursor was crystallized by gradually cooling it to room temperature in 20 hours.

The crystal of this precursor is cut and the cross section is EPM.
Observed at A, Y₁Ba_TwoCu _ThreeO_7-x0.1 in phase
Y of about 30 μm_TwoBaCuO_FivePhases are finely dispersed
Was. Also, the disk-shaped precursor reflecting the seed crystal
The whole crystal is oriented so that the axial direction of the crystal is the c-axis.
Was. The thickness of the obtained precursor crystal is c-axis.
To a 25 mm square and 5 mm thick,
And

Next, this substrate material was fixed with a platinum wire, brought into contact with the melt surface of the melt having the composition of Y: Ba: Cu = 4: 36: 60, and a pulling speed of 1 mm / hr and a rotation speed of After pulling up to about 4 mm under the condition of 100 rpm, the pulling speed was set to 10 mm / hr, and separation from the melt was performed. As a result, the prepared 25 mm
Approximately 4 mm thick, 0.6 to 4 mm across the entire board surface
mm square, mutual a-axis or b-axis forms an angle of 90 ° ± 5 ° or 180 ° ± 5 °, and mutual c-axis tilt angle is 5 °
As a result, a single crystal aggregate of Y ₁ Ba ₂ Cu ₃ O _x arranged as follows was obtained. When the density of this single crystal aggregate was measured, it was 6.22 g / cm ³ . This is about 98% relative density when the theoretical density is 6.34 g / cm ^3.
Is equivalent to

When the obtained single crystal aggregate was analyzed by XRD, it was found to be c-axis oriented so that the direction perpendicular to the prepared substrate surface was the c-axis. Further, when the composition was analyzed by ICP, the molar ratio of Y: Ba: Cu = 0.9 was obtained.
9: 2.01: 3.00, and it was also confirmed that no impurities were contained.

Four single-crystal aggregates were prepared, arranged and polished, and processed into an oxide superconductor target material. And Y
Y ₁ Ba ₂ Cu ₃ is deposited on a Hastelloy tape having an SZ alignment film as an intermediate layer by an ion beam assisted vapor deposition method.
When the _Ox superconducting thin film was formed over a length of 1 m, the amount of the scattered raw material was stable despite the long-time sputtering. The obtained superconducting thin film had a substantially uniform film thickness, and no impurity was found.

The superconducting thin film thus obtained was subjected to XR
When analyzed by D, Y₁Ba_TwoCu _ThreeO_x(00n)
An orientation peak was observed. Also, apply electric power to both ends of 1m tape.
Critical current density at 77K by connecting current terminals to 4 terminals
8 × 10 without external magnetic field^Five
A / cm^Two1.5 × 10 in external magnetic field 2T^FiveA / cm^Two
To obtain a long tape wire with high critical current density characteristics.
I was able to. This is because the amount of scattered raw material is stable
it is conceivable that.

Example 3 BaC of 3N purity as a raw material
The powder of uO ₂ and Sm ₂ BaCuO ₅ is mixed in a molar ratio of Sm: B
a: Cu = 4:36:60, weigh, mix and load into crucible. A crucible made of Sm ₂ O ₃ was used. The temperature was first raised to 1100 ° C. to melt the raw material powder, and then a temperature gradient of 8 ° C./cm was applied up and down so that the upper part of the crucible was on the low temperature side. The temperature was lowered until the upper part of the melt inside reached 1050 ° C.

On the other hand, the production of the substrate material was performed as follows. Each raw material powder of Sm ₂ O ₃ , BaCO ₃ , CuO
After weighing m: Ba: Cu = 1.2: 2.1: 3.1, only BaCO ₃ and CuO were mixed at 880 ° C. for 3 hours.
By calcining for 0 hour, a calcined powder of BaCuO ₂ and CuO was obtained.
(The molar ratio was BaCuO ₂ : CuO = 2.1: 1.0.) Next, the calcined powder and the weighed Sm ₂ were measured.
O ₃ and 0.5 wt% Pt powder (average particle size 0.01 μm)
m) and 10 wt% Ag powder (average particle size 0.45 μm)
m), and then calcined at 900 ° C. for 10 hours in the atmosphere to obtain a calcined powder. The calcined powder was pulverized with a raikai machine to obtain a synthetic powder having an average particle size of about 2 μm. The synthetic powder thus produced was press-molded into a disk having an outer diameter of 53 mm and a thickness of 27 mm to prepare a precursor.

The Sm prepared in advance by the melting method
_1.2 Ba _2.1 Cu _3.1 O _x composition 5mm square, 2mm thick
Was laid on an alumina substrate, and the precursor was placed thereon and placed in a two-zone furnace. And
After raising the temperature inside the furnace from room temperature to 1100 ° C. in 50 hours and holding it for 20 minutes to bring the precursor into a semi-molten state,
A temperature gradient of 5 ° C./cm was applied up and down so that the upper part of the precursor was on the low temperature side, and the temperature was lowered at 10 ° C./min until the upper part temperature of the precursor became 1025 ° C. Here, a seed crystal having a composition of Nd _1.8 Ba _2.4 Cu _3.4 O _x prepared in advance by a melting method is brought into contact with the upper part of the precursor so that the growth direction is parallel to the c-axis. 10 at 5 ° C / hr
After the temperature was lowered to 15 ° C., the temperature was maintained for 40 hours, and then gradually cooled to 945 ° C. over 70 hours. Next, while keeping the temperature of the upper part of the precursor at 945 ° C., the lower part is cooled so that the temperature gradient above and below the precursor is 0 ° C./cm, and then gradually cooled to room temperature in 20 hours. Was crystallized.

The crystal of this precursor was cut and the cross section was EPM.
When observed in A, Sm_{1 + p}Ba_{Two + q}(Cu_1-bAg_b)
_ThreeO_7-x0.1m to 30m Sm in the phase_{2 + r}Ba
_{1 + s}(Cu _1-dAg_d) O_5-yThe phases were finely dispersed. This
Here, p, q, r, s, and y are -0.2 to 0.2, respectively.
And x was a value of -0.2 to 0.6. Ma
B and d are values of 0.0 to 0.05, and on average,
It was about 0.008. In addition, reflecting the seed crystal,
The axial direction of the disk-shaped precursor crystal is c-axis.
The entire crystal was oriented. The thickness direction of the obtained crystal is
It is processed into 25mm square and 5mm thick so as to be c-axis.
This was used as a substrate material.

Next, this substrate material was fixed with a platinum wire, brought into contact with the melt surface of the melt having a composition of Sm: Ba: Cu = 4: 36: 60, and a lifting speed of 2 mm / hr and a rotation speed of After pulling up to about 4 mm under the condition of 100 rpm, the pulling speed was set to 10 mm / hr to separate from the melt. As a result, a thickness of about 4 mm and a height of 0.6 to 4 mm over the entire surface of the prepared 25 mm substrate
Angle, mutual a-axis or b-axis is 90 ± 5 ° or 18
A single crystal aggregate having Sm ₁ Ba ₂ Cu ₃ O _x single crystals arranged at an angle of 0 ° ± 5 ° and having a mutual c-axis tilt angle of 5 ° or less was obtained. When the density of this single crystal aggregate was measured, it was 6.65 g / cm ³ . This is a relative density of about 9 when the theoretical density is 6.84 g / cm ^3.
It corresponds to 7%. When the obtained single crystal aggregate was analyzed by XRD, it was found to be c-axis oriented so that the direction perpendicular to the prepared substrate surface was the c-axis. Further, composition analysis by ICP showed that Sm: Ba: Cu = 1.
03: 1.99: 2.98, and it was also confirmed that no impurities were contained.

Four single-crystal aggregates were prepared, arranged and polished, and processed into an oxide superconductor target material. And Y
Sm ₁ Ba ₂ Cu by ion beam assisted vapor deposition on a Hastelloy tape formed with an SZ alignment film as an intermediate layer.
_{When the 3} O _x superconducting thin film was formed over a length of 1 m, the amount of the scattered raw material was stable in spite of long-time sputtering. The obtained superconducting thin film had a substantially uniform thickness, and no impurities were found. When the superconducting thin film thus obtained was analyzed by XRD, a (00n) orientation peak of Sm ₁ Ba ₂ Cu ₃ O _x was observed. When current terminals were connected to both ends of a 1-meter tape and the critical current density at 77 K was measured by a four-terminal method, 8.5 × 10 ⁵ A / cm ² without an external magnetic field was measured.
A long tape wire having a high critical current density characteristic of 8 × 10 ⁵ A / cm ^{2 in} an external magnetic field of 2T was obtained. This is considered to be an effect of stabilizing the amount of scattered raw materials.

(Example 4) BaC of 3N purity as a raw material
The powder of uO ₂ and Gd ₂ BaCuO ₅ is mixed in a molar ratio of Gd: B
a: Cu = 4:36:60, weigh, mix and load into crucible. A crucible made of Gd ₂ O ₃ was used. First, the temperature was raised to 1100 ° C. to melt the raw material powder. The temperature was lowered until the upper part of the melt inside reached 1025 ° C.

On the other hand, as the prepared substrate material,
Sm _1.2 Ba _2.1 C 25 mm square 5 mm thick in the same manner as
A substrate material having a u _3.1 O _x composition was prepared. Next, this substrate material was fixed with a platinum wire, and the composition was Gd: Ba: Cu = 4:
A 36:60 melt was brought into contact with the melt surface, and a 4 m height was set at 1.5 mm / hr and a rotation speed of 100 rpm.
m, then raise the speed to 10m
It was cut off from the melt at m / hr. as a result,
A thickness of about 4 over the entire surface of the prepared 25 mm substrate
mm, vertical and horizontal 0.6-4mm square, mutual a-axis or b-axis make an angle of 90 ° ± 5 ° or 180 ° ± 5 °,
Gd ₁ Ba ₂ Cu ₃ having a mutual c-axis tilt angle of 5 ° or less
A single crystal aggregate in which O _x single crystals were lined up was obtained. When the density of this single crystal aggregate was measured, it was 6.87.
g / cm ³ . This gives a theoretical density of 6.95 g / c.
This corresponds to about 99% in relative density when m ³ is set.

When the obtained single crystal aggregate was analyzed by XRD, it was found to be c-axis oriented such that the direction perpendicular to the prepared substrate surface was the c-axis. When composition analysis was performed by ICP, Gd: Ba: Cu = 1.
The ratio was found to be 00: 1.99: 3.01, and it was confirmed that no impurities were contained.

Four single-crystal aggregates were prepared, arranged and polished, and processed into an oxide superconductor target material. Then, Gd ₁ Ba ₂ C was deposited on a Hastelloy tape on which an YSZ alignment film was formed as an intermediate layer by an ion beam assisted vapor deposition method.
When the u ₃ O _x superconducting thin film was formed over a length of 1 m, the amount of the scattered raw material was stable despite the long-time sputtering. The obtained superconducting thin film had a substantially uniform film thickness, and no impurity was found. When the superconducting thin film thus obtained was analyzed by XRD, a (00n) orientation peak of Gd ₁ Ba ₂ Cu ₃ O _x was observed. When current terminals were connected to both ends of a 1-meter tape and the critical current density at 77 K was measured by a four-terminal method, the critical current density was 8.0 × 10 ⁵ A / cm ² without an external magnetic field.
A long tape wire having a high critical current density characteristic of 6 × 10 ⁵ A / cm ^{2 in} an external magnetic field of 2T was obtained. This is considered to be an effect of stabilizing the amount of scattered raw materials.

Comparative Example 1 As a raw material, Y ₂ O _{3 having a} purity of 3N was used.
And the raw material powders of BaCO ₃ and CuO in a molar ratio of Y: B
a: After weighing and mixing so that Cu = 1: 2: 3,
The powder was fired twice at 920 ° C. for 20 hours to obtain a synthetic powder. The obtained synthetic powder was formed into a compact by molding it to a length and width of 50 mm and a thickness of 3 mm, and was fired at 930 ° C. for 30 hours to produce an oxide superconductor target material. 5.9 g / cm ³ When the density measured for the target material (about 93% of theoretical density in relative density when formed into a 6.34 g / cm ³⁾
Met.

Using this target material, Y ₁ B was deposited on a Hastelloy tape formed with an YSZ alignment film as an intermediate layer in the same manner as in Example 1 by an ion beam assisted vapor deposition method.
The a ₂ Cu ₃ film formation of O _x superconducting films were carried out over 1 m. However, since the density of the target is low and the bonding between the crystal grains is not uniform, the scattering amount of the raw material during sputtering is not stable, and the thickness of the obtained superconducting thin film is partially uneven. there were. The current terminals were connected to both ends of the 1m tape to increase the critical current density at 77K to 4
When measured by the terminal method, 1 × 1 without external magnetic field
0 ⁵ A / cm ² , 0.2 × 10 ⁵ A / c in external magnetic field 2T
It became a tape wire the m ^2. This is considered to be due to the fact that the scattering amount of the raw material was not stable, and a portion having low characteristics was partially generated, and the characteristics were lowered as a whole.

[0052]

According to the present invention, an oxide superconductor satisfying the size required for the target material is produced in addition to the fact that no binder or a mold is used, so that there is no warpage or cracking, the impurity concentration is low and the relative density is high. . The oxide superconductor is an aggregate of oxide superconductor single crystal particles, has a relative density of 95% or more, the particle size of the oxide superconductor single crystal particles is 0.5 mm or more, The oxide superconductor single crystal particles have a mutual a-axis or b-axis of 90 ° ± 5 ° or 1 °.
The oxide superconductor was characterized by forming an angle of 80 ° ± 5 ° and being aligned with the c-axis side by side so that the mutual c-axis tilt angle was 5 ° or less. Then, when a thin film manufacturing method such as an ion beam assist method or a sputtering method is used, the use of a target material manufactured from this oxide superconductor has the effect of stabilizing the scattering amount of the raw material.

[Brief description of the drawings]

FIG. 1 is a perspective view of an oxide superconductor according to an embodiment of the present invention.

[Explanation of Signs] 1.2.3.4. ... Single crystal of oxide superconductor Oxide superconductor target material 20. 30. Single crystal aggregate of oxide superconductor Prepared molded body

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C30B 29/22 501 C30B 29/22 501H H01B 13/00 565 H01B 13/00 565D H01L 39/24 ZAA H01L 39 / 24 ZAAB (72) Inventor Shuichi Kobayashi 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. 1 F-term in Chubu Electric Power Co., Inc. (Reference) 4G047 JA01 JA03 JB02 JB03 JC02 KE05 KE07 KG01 4G077 AA02 AA03 AA08 AB02 BC53 CF10 DA14 ED04 ED05 ED06 EE06 EG02 HA08 PJ01 PJ04 4K029 BA50 BC04 AD05 DB05 AD05 BA09 BA21 CA34 5G321 AA01 CA04 CA27 DB28 DB30

Claims (10)

[Claims] 1. An aggregate of oxide superconductor single crystal particles having a relative density of 95% or more, wherein the oxide superconductor single crystal particles have a particle size of 0.5 mm or more, and Superconducting single crystal particles have a mutual a-axis or b-axis of 90
° ± 5 ° or 180 ° ± 5 °, and the c-axis tilt angle is less than or equal to 5 ° so that they are oriented and have a size that can be used as a target material. An aggregate of single crystal oxide superconductor particles. 2. An aggregate of oxide superconductor single crystal particles grown from any surface of a thin film, a thick film or a melt of an oxide superconductor having a desired area and oriented in the c-axis, The oxide superconductor single crystal particles have a relative density of 95% or more, the particle size of the oxide superconductor single crystal particles is 0.5 mm or more, and the c-axis tilt angle of the oxide superconductor single crystal particles is 5
An aggregate of single crystal oxide superconductor particles, characterized in that they are oriented so as to be less than or equal to °. 3. A target material produced from an aggregate of the oxide superconductor single crystal particles according to claim 1. 4. A substrate comprising an oxide superconductor having a higher melting point than the oxide superconductor constituting the aggregate of the oxide superconductor single crystal particles according to claim 1 or 2, wherein a surface of the substrate is provided. Is brought into contact with the surface of the appropriately prepared raw material melt and then pulled up to form an aggregate of the oxide superconductor single crystal particles according to claim 1 on the surface of the substrate. For producing an aggregate of single crystal oxide superconductor particles to be formed. 5. The method according to claim 5, wherein the substrate is a ceramic substrate.
The method for producing an aggregate of oxide superconductor single-crystal particles according to claim 4, wherein an oxide superconductor formed into a film is used. 6. An oxide superconductor having a higher melting point than an oxide superconductor constituting an aggregate of the oxide superconductor single crystal particles according to claim 1 or 2 is formed on a ceramic substrate as the substrate. The method for producing an aggregate of oxide superconductor single crystal particles according to claim 4, wherein a film is used. 7. Using a REBaCuO-based material produced by a melting method as a substrate, bringing the surface of the substrate into contact with the surface of a suitably prepared raw material melt, and then pulling up the substrate, thereby lifting the substrate. A method for producing an oxide superconductor, comprising forming oxide superconductor single crystal particles on a surface. 8. After bringing the surface of the substrate into contact with the surface of a suitably prepared raw material melt and then pulling it up, a temperature gradient of 1 to 100 ° C./cm is formed from the melt toward the substrate. The method for producing an aggregate of oxide superconductor single crystal particles according to any one of claims 4 to 7, wherein: 9. The oxide superconductor single crystal according to claim 4, wherein a crucible made of the same element as the raw material element to be melted is used when preparing the raw material melt. A method for producing an aggregate of particles. 10. An oxide superconductor thin film formed using the target material according to claim 3.