JPH11263618A - Re-ba-cu-o-based oxide superconductor and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy the requirements such as electric characteristics, magnetic characteristics, mechanical characteristics and environmental resistance for a superconductor and to obtain a higher critical current density by allowing a twin crystal having a specified plane distance to be present in a specified crystal phase which constitutes the superconducting phase. SOLUTION: The RE-Ba-Cu-O-based oxide superconductor has fine dispersion of RE2(1-q) Ba1+r CUO5+s phase (211 phase) and/or RE4(1-q) Ba2(1+r) CU2 O2(5+s) phase (422 phase) 10 RE1-x Ba2+y CU3 Od phase (123 phase) which constitutes the superconducting phase. In this superconductor, a twin crystal is present in the (123 phase) crystal phase and the distance between the twin crystal planes is <100 nm. Further, the superconductor has an amorphous phase on the interface between the (123 phase) and the (211 phase) and/or the (422 phase). In the formulae, RE represents one or more rare earth metal elements including Y; (x), (y), (d) satisfy -0.3<x<0.3, -0.3<y<0.3, 6.5<d<7.5; (q),(r),(s) satisfy -0.3<q<0.3, -0.3<r<0.3, -0.5<s<0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a superconductor current lead, a superconductor magnetic bearing, a superconductor magnetic shield, a superconductor bulk magnet, and the like. The present invention relates to a RE-Ba-Cu-O-based oxide superconductor capable of satisfying conditions such as properties and required size, and a method for producing the same.

[0002]

2. Description of the Related Art A superconductor for forming a superconductor current lead, a superconductor magnetic bearing, a superconductor magnetic shield, a superconductor bulk magnet, and the like has electrical characteristics, magnetic characteristics, mechanical strength, mechanical strength, and the like required from the function thereof. Conditions such as environmental resistance and required size must be satisfied. As one of the superconductors that have the possibility of satisfying such conditions,
An RE-Ba-Cu-O-based oxide superconductor produced by a so-called melting method can be used. That is, a raw material mixture containing an RE compound (RE is one or more rare earth metal elements containing Y), a Ba compound and a Cu compound is heated and melted to a temperature equal to or higher than the melting point of the raw material mixture, and then a slow cooling step is performed. And a superconductor obtained by growing a crystal. As a specific example thereof, for example, a method described in Japanese Patent Application Laid-Open No. H4-119968 is known. In the method described in this publication, a RE compound, a Ba compound, and a Cu compound are mixed at a predetermined ratio, melt-quenched, and then the obtained solidified product is pulverized again. An RE-Ba-Cu-O-based oxide superconductor is obtained, which is subjected to a step for crystallization and capable of satisfying the above-mentioned conditions to some extent.

[0003]

However, the RE-Ba-Cu-O-based oxide superconductor obtained by the above-mentioned conventional method has the following problems in terms of electrical characteristics, particularly, critical current density.
It has been found that it is not necessarily high enough to respond to recent demands.

When the present inventors studied the cause,
The following points have been elucidated. That is, the superconductor obtained by the above method has a structure in which RE ₂ Ba ₁ Cu _{1 Od} phase (211 phase) is finely dispersed in RE ₁ Ba ₂ Cu _{3 Od} phase (123 phase). The solidified product obtained by quenching is pulverized again to make the 211 phase fine. However, it was found that in the step of melting and slow cooling again, the 211 phase was again aggregated and coarsened. This 211 phase works as a pinning center,
The more finely dispersed, the higher the critical current density. However, the critical current density was suppressed to be low due to the coagulation coarsening.

The present invention has been made in view of the above background, and has electrical and magnetic characteristics applicable to superconductor current leads, superconductor magnetic bearings, superconductor magnetic shields, superconductor bulk magnets, and the like. It is an object of the present invention to provide an RE-Ba-Cu-O-based oxide superconductor having a higher critical current density while satisfying conditions such as mechanical strength, environmental resistance, and required size.

[0006]

Means for Solving the Problems As means for solving the above-mentioned problems, the invention of claim 1 is directed to a RE which constitutes a superconducting phase.
With twins of the crystal is present in the _{1-x Ba 2 + y Cu} 3 O d crystalline phase, RE over Ba over Cu over O-based oxide superconductor, wherein the spacing of twin planes is less than 100nm It is. (However, RE is one or more rare earth metal elements including Y, and RE _{1 -xBa
The 2 + y} Cu ₃ O _d phase means that x, y, and d are each -0.3.
<X <0.3, -0.3 <y <0.3, 6.5 <d <
This is a phase in which one or more phases have a value in the range of 7.5. )

According to a second aspect of the present invention, R
In the E _1-x Ba _{2 + y} Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE
_{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase or RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase in finely dispersed RE over Ba over Cu over O-based oxide superconductor, the _{RE 1-x Ba 2 + y} Cu 3 O d phase And the RE _{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂ O
An RE-Ba-Cu-O-based oxide superconductor having an amorphous phase at an interface with a _{2 (5 + s)} phase. (However, in the RE _1-x Ba _{2 + y} Cu _{3 Od} phase, x, y, and d are −0.3 <x <0.3, −0.3, respectively.
<Y <0.3, 6.5 <d <7.5, at least one phase having a value in the range of
_{2 (1-q) Ba 1} + r CuO 5 + s phase and RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase and the q, r, s respectively -0.3 <q <0.3, -
This is a phase in which at least one phase has a value in the range of 0.3 <r <0.3 and −0.5 <s <0.5. )

[0008] The invention according to claim 3 is characterized in that RE _1-x Ba _{2 + y}
In a Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase and / or RE _{4 (1-q)} Ba
_In an oxide superconductor in which _{2 (1 + r)} Cu ₂ O _{2 (5 + s)} phase is finely dispersed, RE _1-x Ba _{2 + y} Cu ₃
When the value of the a-axis length of the _Od crystal is a and the value of the b-axis length is b, ρ given by ρ = 2 (ba) / (a + b) is 1.5 or more. Is a RE-Ba-Cu-O-based oxide superconductor. (However, RE _1-x Ba
_{The 2 + y} Cu ₃ O _d phase means that x, y, and d are each -0.3.
<X <0.3, -0.3 <y <0.3, 6.5 <d <
Phase takes a value in the range of 7.5 is a phase that occurs more than one, _{also, RE 2 (1-q)} Ba 1 + r CuO 5 + s
Phase and RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂ O
_{The 2 (5 + s)} phase means that q, r, and s are each -0.3 <q
<0.3, -0.3 <r <0.3, -0.5 <s <0.
A phase having a value in the range of 5 is one or more phases. )

According to a fourth aspect of the present invention, R
In the E _1-x Ba _{2 + y} Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE
_{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase or RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase in finely dispersed RE over Ba over Cu over O-based oxide superconductor, the _{RE 1-x Ba 2 + y} Cu 3 O d crystals The twins of the crystals are present in the phase and the spacing between these twin planes is less than 100 nm, and the RE _1-x Ba _{2 + y} Cu
_{3 Od} phase and the RE _{2 (1-q)} Ba _{1 + r} CuO
_{5 + s} phase or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂
An RE-Ba-Cu-O-based oxide superconductor characterized by having an amorphous phase at an interface with an O _{2 (5 + s)} phase. (However, the RE _1-x Ba _{2 + y} Cu _{3 Od} phase has x, y, and d of −0.3 <x <0.3, −0.
3 <y <0.3, 6.5 <d <7.5, and at least one phase having a value in the range of 6.5 <d <7.5.
_{2 (1-q) Ba 1} + r CuO 5 + s phase and RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase and the q, r, s respectively -0.3 <q <0.3, -
This is a phase in which at least one phase has a value in the range of 0.3 <r <0.3 and −0.5 <s <0.5. )

[0010] The invention of claim 5 is characterized in that RE _1-x Ba _{2 + y}
In a Cu ₃ O _d (RE is one or more rare earth metal elements including Y) phase, RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase and / or RE _{4 (1-q)} Ba
_In an oxide superconductor in which _{2 (1 + r)} Cu ₂ O _{2 (5 + s)} phase is finely dispersed, the RE _1-x Ba _{2 + y} C
Twins of the crystal exist in the u ₃ O _d crystal phase, and the distance between these twin planes is less than 100 nm. The value of the a-axis length of the crystal is a, and the value of the b-axis length is b. Sometimes ρ = 2 (b−
a) An RE-Ba-Cu-O-based oxide superconductor, wherein ρ given by (a) / (a + b) is 1.5% or more. (However, in the RE _1-x Ba _{2 + y} Cu _{3 Od} phase, x, y, and d are −0.3 <x <0.3, −
0.3 <y <0.3, 6.5 <d <7.5, at least one phase having a value in the range of 7.5 <d <7.5.
_{2 (1-q) Ba 1} + r CuO 5 + s phase and RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase and the q, r, s respectively -0.3 <q <0.3, -
This is a phase in which at least one phase has a value in the range of 0.3 <r <0.3 and −0.5 <s <0.5. )

[0011] The invention of claim 6 is the present invention, wherein RE _1-x Ba _{2 + y}
In a Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase and / or RE _{4 (1-q)} Ba
_In an oxide superconductor in which _{2 (1 + r)} Cu ₂ O _{2 (5 + s)} phase is finely dispersed, the RE _1-x Ba _{2 + y} C
Twins of the crystal exist in the u ₃ O _d crystal phase, and the distance between these twin planes is less than 100 nm. The value of the a-axis length of the crystal is a, and the value of the b-axis length is b. Sometimes ρ = 2 (b−
a) / (a + b) is not less than 1.5%, and the RE _1-x Ba _{2 + y} Cu _{3 Od} phase and the RE _{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or Or the above RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂
An RE-Ba-Cu-O-based oxide superconductor characterized by having an amorphous phase at an interface with an O _{2 (5 + s)} phase. (However, the RE _1-x Ba _{2 + y} Cu _{3 Od} phase has x, y, and d of −0.3 <x <0.3, −0.
3 <y <0.3, 6.5 <d <7.5, and at least one phase having a value in the range of 6.5 <d <7.5.
_{2 (1-q) Ba 1} + r CuO 5 + s phase and RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase and the q, r, s respectively -0.3 <q <0.3, -
This is a phase in which at least one phase has a value in the range of 0.3 <r <0.3 and −0.5 <s <0.5. )

According to a seventh aspect of the present invention, there is provided the RE-Ba-Cu-O-based oxide superconductor according to any one of the first to sixth aspects, wherein the Ag element is contained in an amount of 1 to 60 wt%. —Ba—Cu—O-based oxide superconductor.

[0013] The invention of claim 8 provides the RE-Ba-Cu-O-based oxide superconductor according to any one of claims 1 to 7, wherein Pt, Pd, Ru, Rh, Ir, Os, R
e, one or more elements of Ce are 0.05 to 5
wt-% RE-Ba-Cu-O
It is a system oxide superconductor.

A ninth aspect of the present invention is directed to a method for preparing an RE compound, wherein RE is Y
, One or two or more rare earth metal elements), Ba
After subjecting the raw material mixture containing the compound and the Cu compound to a treatment including a heat treatment at least in a temperature region higher than the melting point of the raw material mixture, RE _1-x Ba _{2 + y} Cu ₃ O
The method of manufacturing a RE over Ba over Cu over O-based oxide superconductor having a process for crystal growth of the oxide superconductor phase containing _d-phase oxide superconducting containing the _{RE 1-x Ba 2 + y} Cu 3 O d phase RE-Ba-Cu wherein the oxygen partial pressure at the time of carrying out the treatment for growing the body phase is different from the oxygen partial pressure at the step before the treatment step.
A method for producing an O-based oxide superconductor.

According to a tenth aspect of the present invention, the R
In the method for producing an E-Ba-Cu-O-based oxide superconductor, Pt, Pd, Ru, R
h, Ir, Os, Re, Ce metal or one or more of these compounds are added in an amount of 0.05 to 5 wt% (in the case of a compound, the weight of the metal alone is shown). Is a method for producing a RE-Ba-Cu-O-based oxide superconductor.

The invention of claim 11 is the invention of claims 9 to 10
In the method for producing a RE-Ba-Cu-O-based oxide superconductor according to any one of the above,
Wherein the metal or compound is added in an amount of 1 to 60 wt% (in the case of a compound, expressed by the element weight of only Ag).

In the above structure, twins of the crystal are present in the RE _1-x Ba _{2 + y} Cu _{3 Od} crystal phase (123 phase) constituting the superconducting phase, and the distance between these twin planes is less than 100 nm. If there is, or RE _1-x Ba
₂ + y _Cu 3 _{O d} phase and _{RE 2 (1-q) Ba} 1 + r Cu
O _{5 + s} phase (211 phase) or RE _{4 (1-q)} Ba _{2 (}
It has been confirmed that when an amorphous phase exists at the interface with the ( _{1 + r)} Cu ₂ O _{2 (5 + s)} phase (422 phase), these act as a pinning center for stopping magnetic flux and exhibit a high critical current density even under a high magnetic field. .

In addition, Ag, Pt, Pd,
It has been confirmed that the above effects become more remarkable when elements such as Ru, Rh, Ir, Os, Re, and Ce are appropriately added.

Further, when manufacturing a RE—Ba—Cu—O-based oxide superconductor, the solidification temperature changes depending on the oxygen concentration in the atmosphere. A low oxygen concentration lowers the coagulation temperature, while a high oxygen concentration raises the coagulation temperature. By utilizing this fact, it is possible to react at a low temperature by melting and solidifying under a low oxygen concentration, and it is possible to make the interval between twin planes in the oxide superconductor approximately 70 nm or less, at least less than 100 nm. At the same time, it became possible to finely disperse the 211 phase while suppressing the coarsening of the 211 phase. In addition, RE _1-x Ba _{2 + y} Cu _{3 Od} phase and RE
_{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase or RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) an amorphous phase at the interface between the phases is generated, serves as a pinning center to these twin plane and an amorphous phase and 211 phase stops flux, high magnetic field It has been confirmed that a high critical current density is exhibited even below.

Further, a predetermined heat treatment is applied to the raw material mixture containing the RE compound, the Ba compound, and the Cu compound, and the pulverized and molded material is heated to a semi-molten state. In the step of growing the crystal while changing the partial pressure from the partial pressure side to the high oxygen partial pressure side, the oxygen partial pressure may be changed, but the change rate is preferably 10% or more. At this time, it does not depend on the absolute value of the oxygen partial pressure. Also,
The temperature at which the crystal is grown is RE _{1 −} xBa under the oxygen partial pressure (low oxygen partial pressure side) when the raw material mixture is brought into a semi-molten state.
_The temperature may be higher than the temperature at which the _{2 + y} Cu _{3 Od} phase grows, but preferably the temperature is lowered to a temperature higher by 1 to 50 ° C.
It is desirable to grow the crystal by changing the oxygen partial pressure to a higher oxygen partial pressure while maintaining the temperature or gradually cooling at a rate of 0.1 to 5 ° C./hr. In addition, a raw material containing a RE compound, a Ba compound, and a Cu compound as main elements is melted and crystallized to obtain a RE _1-x Ba _{2 + y} Cu _{3 Od} phase,
_{2 (1-q) Ba 1} + r CuO 5 + s phase or RE
_{4 (1-q)} when _{Ba 2 (1 + r) Cu} 2 O 2 (5 + s) phase to produce an oxide superconductor having, by atmospheric and temperature conditions, occur interchangeability of Ba and RE, the excessive substitution Decreases critical current density characteristics and critical temperature characteristics of superconductors. The amount of oxygen also changes depending on the substitution and the firing atmosphere. The range of these x, y, d, d, q, r is:
-0.3 <x <0.3, -0.3 <y <0.
3,6.5 <d <7.5, -0.3 <q <0.3,-
It is desirable to take a value in the range of 0.3 <r <0.3, -0.5 <s <0.5.

The material crystallized by such a method is thereafter annealed in an atmosphere having an oxygen partial pressure of 80 to 100%, whereby high superconducting characteristics such as critical temperature and critical current density characteristics can be obtained. Become like The annealing temperature conditions at this time preferably include a step of holding or slowly cooling for at least 100 hours in a temperature range of 700 ° C. to 300 ° C. Then, after this annealing treatment, efficient oxygen is supplied to the _{RE 1-x Ba 2 + y} Cu 3 O d crystal, the difference between the axial length of the value b of the axial length of the values a and b axes of a shaft growing. Here, ρ = 2 (ba) /
Ρ given by (a + b) is desirably 1.5% or more,
The higher the value, the higher the characteristics can be obtained, but it is difficult to reach 2.2% or more.

It has been confirmed that when Pt is contained in the range of 0.05 to 5 wt%, the RE ₂ BaCuO ₅ phase becomes fine and exhibits high characteristics. Also, Pt,
Metal or compound powder of Pd, Ru, Rh, Ir, Os, Re, Ce is 0.05 to 5 wt%, preferably 0.1 to 5 wt% .
It has been confirmed that even when contained in the range of 4 to 0.6 wt% , high characteristics are similarly exhibited.

Further, when Ag is finely dispersed in the crystal, microcracks are reduced, and the magnetic properties, mechanical strength,
Water resistance is improved. At this time, the effect is low when the content is 1 wt% or less, and when the content is more than 60 wt%, the superconducting current becomes difficult to flow and the characteristics are deteriorated. A more preferable range of the Ag content is 10 to 30 wt%.

[0024]

(Embodiment 1) Y ₂ O ₃ , BaCO 3
_3. Each raw material powder of CuO was prepared as Y: Ba: Cu = 18: 2
4: 34% and weighed 0.5wt% P
t powder was added and mixed. Next, the temperature of the mixed powder was raised from room temperature to 880 ° C. in the air for 10 hours, and the temperature was maintained for 30 hours. The calcined powder was pulverized with a raikai machine to have an average particle size of about 20 μm. Next, this is 53 mm in outer diameter
A compact was produced by press molding into a 28 mm thick disk.

After placing the compact on an alumina substrate to make it in a semi-molten state at 1025 ° C. in an oxygen partial pressure of 1%, a temperature gradient of 5 ° C./cm is applied vertically so that the upper portion of the compact is on the low temperature side. In addition, 10 ° C / min until the sample upper part reaches 975 ° C.
And the temperature was lowered, and Y ₁ (Ba _0.75 Sr
_{0.25) 2 Cu 3 O 7-} z phase to _Y 2 BaCuO ₅ phase is dispersed seed crystal growth direction is brought into contact with the upper portion of the molded body so as to be parallel to the c axis. Next, crystallization was performed from the seed crystal side by increasing the oxygen partial pressure from 1% to 100%. Further, the temperature is lowered at 1 ° C / hour to 900 ° C,
From there, slow cooling was performed to room temperature in 50 hours.

The crystallized compact was placed in a furnace capable of gas replacement. First, 0.1 Torr by rotary pump
After the inside of the furnace was evacuated to a pressure of r, oxygen gas was flown into the atmosphere at atmospheric pressure where the oxygen partial pressure was 95% or more. Thereafter, the temperature was raised from room temperature to 600 ° C. for 10 hours while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min.
The temperature was kept at 100 ° C. for 100 hours, the temperature was lowered to room temperature in about 2 hours, and the temperature was raised again to 500 ° C. in 10 hours, and then 300 ° C.
Slowly from 200 ° C to room temperature for 1 hour.
The temperature was lowered at 0 hours.

The obtained material had a structure in which the entire material was oriented along the c-axis, reflecting the seed crystal, and 211 phases were finely dispersed in 123 phases. 80% or more of this 211 phase is 2μ
m or less. Further, when twins generated in the 123 phase were observed by a transmission electron micrograph, twin planes were finely arranged at intervals of about 50 nm as shown in FIG. FIG. 2 shows the results of observation of the 123 phase and 211 phase with a transmission electron microscope. FIG. 3 shows an enlarged boundary. FIG. 3 shows a 123 phase, an amorphous phase and a 211 phase.

[0028] The critical temperature (T
c) was 90K. The magnetic field dependence of the critical current density at a temperature of 77 K showed a high value even under a high magnetic field around 1 T as shown in FIG.

Example 2 Sm ₂ O ₃ , BaCO ₃ , C
Each raw material powder of uO was prepared as Sm: Ba: Cu = 18: 24: 3.
The mixture was weighed so as to obtain a Pt. 4, and 0.5 wt% of Pt powder was further added and mixed. Next, the temperature of the mixed powder was raised from room temperature to 880 ° C. in the air for 10 hours, and the temperature was maintained for 30 hours. The calcined powder was pulverized with a raikai machine to have an average particle size of about 20 μm. Next, this was applied to an outer diameter of 53 mm and a thickness of 2
A compact was produced by press molding into an 8 mm disk shape.

After placing this compact on an alumina substrate to make it in a semi-molten state at 1085 ° C. in an oxygen partial pressure of 1%, a temperature gradient of 5 ° C./cm is applied vertically so that the upper portion of the compact is on the low temperature side. In addition, 10 ° C / mi until the sample upper part reaches 1035 ° C.
n, and Nd _1.1 Ba _1.9 prepared in advance.
A seed crystal in which the Nd ₄ Ba ₂ Cu ₂ O ₁₀ phase is dispersed in the Cu ₃ O _7-z phase is brought into contact with the upper part of the compact so that the growth direction is parallel to the c-axis. Next, the oxygen partial pressure is increased from 1% to 10%.
By increasing to 0%, crystallization was performed from the seed crystal side. The temperature was further decreased to 960 ° C. at 1 ° C./hour, and then gradually cooled to room temperature in 50 hours.

The crystallized compact was placed in a furnace capable of gas replacement. First, 0.1 Torr by rotary pump
After the inside of the furnace was evacuated to a pressure of r, oxygen gas was flown into the atmosphere at atmospheric pressure where the oxygen partial pressure was 95% or more. Thereafter, the temperature was raised from room temperature to 600 ° C. for 10 hours while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min.
The temperature was kept at 100 ° C. for 100 hours, the temperature was lowered to room temperature in about 2 hours, and the temperature was raised again to 500 ° C. in 10 hours, and then 300 ° C.
Slowly from 200 ° C to room temperature for 1 hour.
The temperature was lowered at 0 hours.

In the obtained material, the whole material is oriented along the c-axis reflecting the seed crystal, and the value of the Sm _{1 +} xBa _{2 +} yCu _{3 Od} phase ((x, y, d) is determined by energy dispersive photoelectron spectroscopy. And (x, y, d) = (0.1, −
0.1, 6.95), (0, 0, 6.9), (-0.
1,0.1,6.85). )
It had a structure in which the Sm ₂ BaCuO ₅ phase was finely dispersed. 80% or more of the 211 phase was refined to 2 μm or less. Also, according to the transmission electron micrograph, 1
When twins generated in the 23 phases were observed, they were finely arranged at intervals of about 50 nm as in Example 1. Further Sm
_{1 + x Ba 2 + y CuO} d phase similar amorphous phase as in Example 1 at the interface 211 phase was present.

[0033] The critical temperature (T
c) was 92K. The magnetic field dependence of the critical current density at a temperature of 77 K showed a high value even under a high magnetic field around 1-2 T as shown in FIG.

Example 3 Nd ₂ O ₃ , BaCO ₃ , C
Each raw material powder of uO was Nd: Ba: Cu = 18: 24: 3
4 and then 0.5 wt% of Ce powder, 0.5 wt% of Pt powder and 10 wt% of Ag powder were added and mixed. Next, the temperature of the mixed powder was raised from room temperature to 880 ° C. in the air for 10 hours, and the temperature was maintained for 30 hours. The calcined powder was pulverized with a raikai machine to have an average particle size of about 20 μm. Next, this was applied to an outer diameter of 53 mm and a thickness of 2
A compact was produced by press molding into an 8 mm disk shape.

After placing this compact on an alumina substrate to make it in a semi-molten state at 1065 ° C. in an oxygen partial pressure of 1%, a temperature gradient of 5 ° C./cm is applied vertically so that the upper portion of the compact is on the low temperature side. In addition, 10 ° C / mi until the sample upper part reaches 1015 ° C.
n, and Nd _1.1 Ba _1.9 prepared in advance.
A seed crystal in which the Nd ₄ Ba ₂ Cu ₂ O ₁₀ phase is dispersed in the Cu ₃ O _7-z phase is brought into contact with the upper part of the compact so that the growth direction is parallel to the c-axis. Next, the oxygen partial pressure is increased from 1% to 10%.
By increasing to 0%, crystallization was performed from the seed crystal side. The temperature was further lowered to 940 ° C. at 1 ° C./hour, and then gradually cooled to room temperature in 50 hours.

The crystallized compact was placed in a furnace capable of gas replacement. First, 0.1 Torr by rotary pump
After the inside of the furnace was evacuated to a pressure of r, oxygen gas was flown into the atmosphere at atmospheric pressure where the oxygen partial pressure was 95% or more. Thereafter, the temperature was raised from room temperature to 600 ° C. for 10 hours while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min.
The temperature was kept at 100 ° C. for 100 hours, the temperature was lowered to room temperature in about 2 hours, and the temperature was raised again to 500 ° C. in 10 hours, and then 300 ° C.
Slowly from 200 ° C to room temperature for 1 hour.
The temperature was lowered at 0 hours.

In the obtained material, the entire material is oriented along the c-axis reflecting the seed crystal, and the value of the Nd _{1 +} xBa _{2 +} yCu _{3 Od} phase ((x, y, d) is determined by energy dispersive photoelectron spectroscopy. And (x, y, d) = (0.1, −
0.1, 6.95), (0, 0, 6.9), (-0.
1,0.1,6.85). )
It had a structure in which Nd ₄ Ba ₂ Cu ₂ O ₁₀ phase was finely dispersed. 80% or more of the 422 phase was refined to 5 μm or less. When a twin generated in the Nd _{1 + x} Ba _{2 + y} Cu _{3 Od} phase was observed by a transmission electron micrograph, the twin plane was found to be about 50 as in Example 1.
It was finely aligned with the nm interval. Further, Nd _{1 +} xBa
An amorphous phase similar to that in Example 1 was present at the interface between the _{2 + y} Cu _{3 Od} phase and the 422 phase.

The critical temperature (T
c) was 94K. The magnetic field dependence of the critical current density at a temperature of 77 K showed a high value even under a high magnetic field around 1-2 T as shown in FIG.

Example 4 Nd ₂ O ₃ , BaCO ₃ , C
Each raw material powder of uO was Nd: Ba: Cu = 5: 30: 65
Was weighed and mixed. Next, this mixed powder is
In the air, the temperature was raised from room temperature to 880 ° C. in 10 hours,
After holding for a period of time, the temperature was lowered to room temperature over a period of 10 hours to perform firing. The calcined powder was pulverized with a raikai machine to have an average particle size of about 20 μm. Next, this is
It was placed in a 50 mm, 80 mm high Nd ₂ O ₃ crucible and heated to 1065 ° C. in 1% oxygen partial pressure for 10 hours to form a melt. Next, at the tip of the rod, use MgO with a diameter of 3 mm and a thickness of 5 mm.
Was placed, and the tip was immersed in this melt at about 2 mm while rotating at 120 rpm. Here, the oxygen partial pressure was increased from 1% to 100%, and then the seed crystal was 0.1 mm.
The crystal was grown by pulling at a rate of / hour.

The grown crystal was placed in a furnace capable of gas replacement. First, 0.1 Torr with a rotary pump
After the inside of the furnace was evacuated, oxygen gas was flowed into the furnace to form an oxygen atmosphere at atmospheric pressure with an oxygen partial pressure of 95% or more. Thereafter, while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min, the temperature was raised from room temperature to 700 ° C. for 10 hours.
, And the temperature was lowered to room temperature in about 2 hours.
After the temperature was raised to 00 ° C. in 10 hours, the temperature was gradually reduced to 300 ° C. over 200 hours, and the temperature was lowered from 300 ° C. to room temperature in 10 hours.

In the obtained material, the entire material is oriented along the c-axis,
The value of the Nd _{1 + x} Ba _{2 + y} Cu _{3 Od} phase ((x, y, d) was measured by energy dispersive photoelectron spectroscopy, and (x, y, d) = (0.1, −0.1, 6) .9
5), (0, 0, 6.9), (-0.1, 0.1, 6..
85) were mainly present. ) Were mainly present). Further, when twins generated in the Nd _{1 +} xBa _{2 +} yCu _{3 Od} phase were observed by a transmission electron micrograph, the twin planes were finely arranged at intervals of about 50 nm as in Example 1. The critical temperature (Tc) of the obtained disk-shaped material was 94K. Temperature 77
K, critical current density in external magnetic field 2T is 20,000 A / cm
² and a high value even under a high magnetic field.

Example 5 Y ₂ O ₃ , BaCO ₃ , Cu
Each raw material powder of O was weighed so that Y: Ba: Cu = 18: 24: 34, melted in a Pt crucible at 1400 ° C. for 30 minutes, poured into a copper plate and rapidly cooled to solidify. This solidified product was pulverized by a pot mill to an average particle size of 2 μm. Next, the pulverized mixed powder was again removed from the room temperature to 920 in air.
The temperature was raised to 10 ° C. for 10 hours, maintained for 10 hours, and then lowered to room temperature over 10 hours for firing. The calcined mixed powder was pulverized by a raikai machine to have an average particle size of about 10 μm. Next, this is an outer diameter of 53 mm and a thickness of 28 m.
m was press-molded into a disk shape to produce a molded body.

After placing this compact on an alumina substrate to make it in a semi-molten state at 1025 ° C. in an oxygen partial pressure of 1%, a temperature gradient of 5 ° C./cm was applied vertically so that the upper portion of the compact was on the low temperature side. In addition, 10 ° C / min until the sample upper part reaches 975 ° C.
And the temperature was lowered, and Y ₁ (Ba _0.75 Sr
_{0.25) 2 Cu 3 O 7-} z phase to _Y 2 BaCuO ₅ phase is dispersed seed crystal growth direction is brought into contact with the upper portion of the molded body so as to be parallel to the c axis. Next, crystallization was performed from the seed crystal side by increasing the oxygen partial pressure from 1% to 100%. Further, the temperature is lowered at 1 ° C / hour to 900 ° C,
From there, slow cooling was performed to room temperature in 50 hours.

The crystallized compact was placed in a furnace capable of gas replacement, and was subjected to oxygen annealing under the following two temperature conditions. First, 0.1T with a rotary pump
After the furnace was evacuated to orr, oxygen gas was flown into the oxygen atmosphere at an atmospheric pressure in which the oxygen partial pressure was 95% or more, and thereafter, oxygen gas was flown into the furnace at a flow rate of 0.5 L / min. (Temperature condition 1) The temperature was raised from room temperature to 600 ° C. in 15 minutes,
The temperature is kept at 600 ° C. for 100 hours, taken out of the furnace, rapidly cooled to room temperature, raised again to 500 ° C. for 2 hours, then kept at 500 ° C. for 100 hours, and cooled to room temperature in about 10 hours. (Temperature condition 2) The temperature is raised from room temperature to 500 ° C. for 2 hours, then kept at 500 ° C. for 100 hours, and lowered to room temperature in about 10 hours.

The obtained material had a structure in which the entire material was oriented along the c-axis reflecting the seed crystal, and 211 phases were finely dispersed in 123 phases. 80% or more of this 211 phase is 2μ
m or less. Further, when twins generated in the 123 phase were observed by a transmission electron micrograph, they were finely arranged at intervals of about 50 nm as in Example 1. Further, an amorphous phase similar to that in Example 1 was present at the interface between the 123 phase and the 211 phase.

FIG. 6 is a view showing the measurement result of the critical temperature of the superconductor manufactured by annealing under the temperature condition 1 of the fifth embodiment. FIG. 7 is a diagram showing the superconductor manufactured by annealing at the temperature condition 2 of the fifth embodiment. It is a figure showing a measurement result of a critical temperature of a body.
As shown in these figures, both critical temperatures (Tc) were about 90K.

FIG. 8 is a diagram showing the magnetic field dependence of the critical current density of the superconductor manufactured by annealing at the temperature condition 1 of the fifth embodiment. FIG. 9 is manufactured by annealing at the temperature condition 2 of the fifth embodiment. FIG. 5 is a diagram showing the magnetic field dependence of the critical current density of the superconductor thus obtained. These figures show that the temperatures are 77K and 70K.
It shows the measurement results of the magnetic field dependence of the critical current density in each case of K and 65K. As shown in these figures, the value was high even under a high magnetic field of about 1 to 4 T, and the effect was particularly enhanced when cooled to about 65K.

Further, a sample of about 1 cubic cm was cut out from the vicinity of the end of these disc-shaped materials,
And crushed by XRD (X-ray diffractometer) to obtain a lattice constant a,
b and c were measured. Here, the c-axis is an axis approximately three times as long as the a-axis and the b-axis. In a and b, the longer axis is the b-axis and the shorter is the a-axis. An index (hkl) is used to determine the lattice constant.
Are (200), (020) and (006), respectively.
Was performed using the peak of

FIG. 10 shows the values of ρ from the lattice constants a, b, and c obtained from the XRD measurement results of the oxide superconductors of Example 5 and Comparative Example 2 described later. It is a figure showing the relation with a value. Where ρ
(%) Is a value indicating the orthorhombic property, and is a value obtained by dividing the difference between the a-axis length value a (lattice constant) and the b-axis length value b (lattice constant) by the average of a and b. Where ρ = 2 (ba) / (a +
This is the value defined in b). FIG. 11 shows the critical current densities (J around 1 to 4 T at 65 K and 70 K of the oxide superconductors of Example 5 and Comparative Example 2 described later.
It is a figure which shows the relationship between the peak value of c) and the value of (rho) in a graph. The material annealed under the temperature conditions of the present embodiment has a relatively large value of ρ, that is, a large orthorhombic property,
It can be seen that Jc is high.

Comparative Example 1 Y ₂ O ₃ , BaCO ₃ , Cu
Each raw material powder of O was weighed so that Y: Ba: Cu = 18: 24: 34, and 0.5 wt% Pt powder was further added and mixed. Next, the temperature of the mixed powder was raised from room temperature to 880 ° C. in the air for 10 hours, and the temperature was maintained for 30 hours. The calcined powder was pulverized with a raikai machine to have an average particle size of about 20 μm. Next, this was added to an outer diameter of 53 mm and a thickness of 28 mm.
A compact was produced by press molding into a disk having a diameter of mm.

After placing this compact on an alumina substrate to make it in a semi-molten state at 1100 ° C. in the atmosphere, a temperature gradient of 5 ° C./cm was applied up and down so that the upper part of the compact was on the low temperature side. Temperature was lowered at 10 ° C./min until the temperature reached 1000 ° C., and Nd _1.1 Ba _1.9 Cu ₃ O prepared in advance was prepared.
A seed crystal in which the Nd ₄ Ba ₂ Cu ₂ O ₁₀ phase was dispersed in the _7-z phase was brought into contact with the upper part of the compact so that the growth direction was parallel to the c-axis. Next, the temperature was lowered to 900 ° C. at 1 ° C./hour, and then gradually cooled to room temperature in 50 hours.

The crystallized compact was placed in a furnace capable of gas replacement. First, 0.1 Torr by rotary pump
After the inside of the furnace was evacuated to a pressure of r, oxygen gas was flown into the atmosphere at atmospheric pressure where the oxygen partial pressure was 95% or more. Thereafter, while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min, the temperature was raised from room temperature to 500 ° C. for 10 hours, and then gradually cooled from that temperature to 300 ° C. over 200 hours. The temperature was lowered over time.

The overall resulting material reflecting the seed crystal material is oriented in the _{c-axis, Y 1 Ba 2 CuO 3 O} d phase to 211
Although the phase had a finely dispersed structure, the 211 phase had a relatively large average particle size of about 5 μm. In addition, according to a transmission electron micrograph, it was confirmed that Y ₁ Ba ₂
Observation of twins generated in the Cu _{3 Od} phase revealed that FIG.
The spacing between twin planes was wide as shown in FIG. Critical temperature (Tc) of the obtained disk-shaped material
Was 90K. The magnetic field dependence of the critical current density at a temperature of 77 K showed a low value under a high magnetic field around 1-2 T as shown in FIG.

(Comparative Example 2) This comparative example is an example in which the crystallization step is the same as in Example 5, and the annealing temperature conditions are changed as follows. That is, from room temperature to 300 ° C.
After the temperature was raised over a period of time, the temperature was maintained at 300 ° C. for 100 hours and the temperature was lowered to room temperature in about 3 hours.

The obtained material had a structure in which the entire material was oriented along the c-axis reflecting the seed crystal and 211 phases were finely dispersed in 123 phases. 80% or more of this 211 phase is 2μ
m or less. However, when the twins generated in the 123 phase were observed by a transmission electron micrograph, the interval was sparse, that is, 100 nm or more.

FIG. 12 is a graph showing the results of measurement of the critical temperature of an oxide superconductor manufactured by annealing under the temperature conditions of Comparative Example 2, and FIG. FIG. 4 is a diagram showing the magnetic field dependence of the critical current density of a superconductor. From FIG. 12, the critical temperature (Tc) is about 8
It turns out that it is 8K. Also, FIG.
The results were measured with K, 70K, and 65K, and Jc was low under a high magnetic field as shown in this figure.

Further, the comparative example 2 is also the same as the example 5
As shown in FIG. 10, the lattice constants a, b, and c were obtained in the same manner as described above, ρ was obtained, and the peak value of the critical current density in each case was obtained. FIG. 11 is a graph showing the relationship between ρ and the peak value of the electric field current density by plotting these results. FIG. 11 also shows the relationship between the point where the rate of decrease in the critical current density (Jc) around 1 to 4T at the temperature of 65K and 70K is the least and ρ. It can be seen that the material annealed under the temperature conditions of this comparative example has a relatively small value of ρ, that is, a low orthorhombicity, and thus a low Jc.

[0058]

As described in detail above, R according to the present invention
E over Ba over Cu over O-based oxide superconductor, the spacing of these twin planes with twins of the crystal is present in _{RE 1-x Ba 2 + y} Cu 3 O d crystalline phase constituting the superconducting phase 100
nm or RE _1-x Ba
_{2 + y} Cu ₃ O _d phase and RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu
An amorphous phase is provided at the interface with the ₂ O _{2 (5 + s)} phase, or Ag, Pt, Pd, R
By appropriately adding u, Rh, Ir, Os, Re, Ce and the like, it is possible to obtain a higher critical current density. In addition, the production method of the present invention provides RE _1-x
By making the oxygen partial pressure during the crystal growth of the oxide superconductor phase containing the Ba _{2 + y} Cu _{3 Od} phase different from the oxygen partial pressure in the step before this processing step, the above RE-Ba- This makes it possible to produce a Cu-O-based oxide superconductor.

[Brief description of the drawings]

FIG. 1 is a view showing a transmission electron micrograph of twins formed on a RE—Ba—Cu—O-based oxide superconductor according to Example 1. FIG.

FIG. 2 shows a Y ₁ Ba ₂ Cu _{3 Od} phase and a Y ₂ BaC in the RE—Ba—Cu—O-based oxide superconductor according to Example 1.
shows a transmission electron micrograph of the interface between uO ₅ phase.

FIG. 3 is a view showing a partially enlarged photograph of FIG. 2;

FIG. 4 is a diagram showing the magnetic field dependence of the critical current density of the oxide superconductors manufactured in Examples 1 to 3 and Comparative Example 1.

FIG. 5 shows a Y ₁ Ba ₂ Cu ₃ O _d phase and a Y ₂ BaC in the RE—Ba—Cu—O-based oxide superconductor according to Comparative Example 1.
shows a transmission electron micrograph of the interface between uO ₅ phase.

FIG. 6 is a view showing a measurement result of a critical temperature of a superconductor manufactured by performing an annealing treatment under temperature condition 1 of Example 5. .

FIG. 7 is a view showing a measurement result of a critical temperature of a superconductor manufactured by annealing under temperature condition 2 in Example 5.

FIG. 8 is a diagram showing the magnetic field dependence of the critical current density of a superconductor manufactured by annealing under the temperature condition 1 of Example 5.

FIG. 9 is a diagram showing the magnetic field dependence of the critical current density of a superconductor manufactured by annealing under temperature condition 2 in Example 5.

FIG. 10 shows lattice constants a, b, and c obtained from XRD measurement results of oxide superconductors of Example 5 and Comparative Example 2 described later.
Is a diagram showing the relationship between the value of ρ and the peak value of the critical current density.

FIG. 11 is a graph showing the relationship between the peak value of critical current density (Jc) and the value of ρ around 1 to 4 T at temperatures of 65 K and 70 K of the oxide superconductors of Example 5 and Comparative Example 2 described later. FIG.

FIG. 12 is a diagram showing a measurement result of a critical temperature of an oxide superconductor manufactured by annealing under the temperature conditions of Comparative Example 2. .

13 is a diagram showing the magnetic field dependence of the critical current density of an oxide superconductor manufactured by annealing under the temperature conditions of Comparative Example 2. FIG.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mamoru Sato 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. 20-1 Inside Chubu Electric Power Co., Inc.

Claims (11)

[Claims] 1. RE _1-x Ba _{2 + y} constituting a superconducting phase
While twins of the crystal exist in the Cu _{3 Od} crystal phase,
An RE-Ba-Cu-O-based oxide superconductor, wherein the distance between these twin planes is less than 100 nm. (Where, RE is one or more rare earth metal elements including _{Y, RE 1 -x Ba 2 +} y Cu 3 O d phase A x, y, d respectively -0.3 <x <0. 3, -0.3
<Y <0.3, 6.5 <d <7.5. ) 2. RE _1-x Ba _{2 + y} constituting a superconducting phase
In a Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE _{2 (1-q)} Ba _{1 + r} C
uO5 _{+ s} phase and / or RE4 _(1-q) Ba
_{2 (1 +} r) in the _{Cu 2 O 2 (5 + s} ) phase is finely dispersed RE over Ba over Cu over O-based oxide superconductor, the _{RE 1-x Ba 2 + y} Cu 3 O d phase and the RE
_{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5+ s) R , characterized in that it comprises an interface amorphous phase of the phase
E-Ba-Cu-O-based oxide superconductor. (However, RE
_{The 1-x} Ba _{2 + y} Cu ₃ O _d phase has x, y, and d of −0.3 <x <0.3, −0.3 <y <0.3, and 6.
One or more phases having a value in the range of 5 <d <7.5 are present, and RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase and _{RE 4 (1-q) Ba} 2 (1 + r) Cu
₂ O _{2 (5 + s)} is a phase q, r, s respectively -0.3
<Q <0.3, -0.3 <r <0.3, -0.5 <s <
A phase having a value in the range of 0.5 is one or more phases. ) 3. An RE _1-x Ba _{2 + y} Cu _{3 Od} (RE is one or more rare earth metal elements containing Y) phase and a RE _{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂ O
_In an oxide superconductor in which _{2 (5 + s)} phases are finely dispersed, when the value of the a-axis length of RE _1-x Ba _{2 + y} Cu ₃ O _d crystal is a and the value of the b-axis length is b, ρ = 2 (ba) /
The RE-Ba-Cu-O-based oxide superconductor, wherein ρ given by (a + b) is 1.5% or more.
(However, the RE _1-x Ba _{2 + y} Cu _{3 Od} phase is x,
y and d are -0.3 <x <0.3 and -0.3 <y, respectively.
<0.3, 6.5 <d <7.5, at least one phase having a value in the range of 7.5, and RE _{2 (1-q)}
Ba _{1 + r} CuO _{5 + s} phase and RE _{4 (1-q)} Ba
_{2 (1 + r)} Cu ₂ O _{2 (5 + s)} phase means that q, r, and s are -0.3 <q <0.3, -0.3 <r <0.
This is a phase in which one or more phases have a value in the range of 3, -0.5 <s <0.5. ) 4. RE _1-x Ba _{2 + y} constituting a superconducting phase
In a Cu ₃ O _d (RE is one or more rare earth metal elements containing Y) phase, RE _{2 (1-q)} Ba _{1 + r} C
uO5 _{+ s} phase and / or RE4 _(1-q) Ba
In _{2 (1 + r) Cu 2} O 2 (5 + s) phase is finely dispersed RE over Ba over Cu over O-based oxide superconductor, twinning of the _{RE 1-x Ba 2 + y} Cu 3 O d crystalline phase in the crystal And the distance between these twin planes is less than 100 nm, wherein the RE _1-x Ba _{2 + y} Cu ₃ O _d phase and the RE
_{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5+ s) R , characterized in that it comprises an interface amorphous phase of the phase
E-Ba-Cu-O-based oxide superconductor. (However, RE
_{The 1-x} Ba _{2 + y} Cu ₃ O _d phase has x, y, and d of −0.3 <x <0.3, −0.3 <y <0.3, and 6.
One or more phases having a value in the range of 5 <d <7.5 are present, and RE _{2 (1-q)} Ba _{1 + r} Cu
O _{5 + s} phase and _{RE 4 (1-q) Ba} 2 (1 + r) Cu
₂ O _{2 (5 + s)} is a phase q, r, s respectively -0.3
<Q <0.3, -0.3 <r <0.3, -0.5 <s <
A phase having a value in the range of 0.5 is one or more phases. ) 5. An RE _1-x Ba _{2 + y} Cu _{3 Od} (RE is one or more rare earth metal elements containing Y) phase and an RE _{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂ O
₂ in _{(5 + s)} phase oxide superconductor dispersed finely, the _{RE 1-x Ba 2 + y} Cu 3 O twinning of the crystals present in the _d-crystal phase, and 100nm spacing of these twin planes
When the value of the a-axis length of the crystal is a and the value of the b-axis length is b, ρ given by ρ = 2 (ba) / (a + b) is 1.5
% Or more of RE-Ba-Cu-O-based oxide superconductor. (However, RE _1-x Ba _{2 + y} Cu ₃
The _Od phase means that x, y, and d are -0.3 <x <0.
A phase having at least one phase having a value in a range of 3, −0.3 <y <0.3, 6.5 <d <7.5;
_{RE 2 (1-q) Ba} 1 + r CuO 5 + s phase and RE
_{4 (1-q) Ba 2} (1 + r) Cu 2 O 2 (5 + s) phase and the q, r, s respectively -0.3 <q <0.3, -
This is a phase in which at least one phase has a value in the range of 0.3 <r <0.3 and −0.5 <s <0.5. ) 6. An RE _1-x Ba _{2 + y} Cu _{3 Od} (RE is one or more rare earth metal elements containing Y) phase and a RE _{2 (1-q)} Ba _{1 + r} CuO _{5 + s} phase and / or RE _{4 (1-q)} Ba _{2 (1 + r)} Cu ₂ O
₂ in _{(5 + s)} phase oxide superconductor dispersed finely, the _{RE 1-x Ba 2 + y} Cu 3 O twinning of the crystals present in the _d-crystal phase, and 100nm spacing of these twin planes
When the value of the a-axis length of the crystal is a and the value of the b-axis length is b, ρ given by ρ = 2 (ba) / (a + b) is 1.5
Not less than%, further, the _{RE 1-x Ba 2 + y} Cu 3 O d phase and said _{RE 2 (1-q) Ba} 1 + r CuO 5 + s phase and / or the _{RE 4 (1-q) Ba} 2 (1 + r) Cu ₂ O
An RE-Ba-Cu-O-based oxide superconductor having an amorphous phase at an interface with a _{2 (5 + s)} phase.
(However, the RE _1-x Ba _{2 + y} Cu _{3 Od} phase is x,
y and d are -0.3 <x <0.3 and -0.3 <y, respectively.
<0.3, 6.5 <d <7.5, at least one phase having a value in the range of 7.5, and RE _{2 (1-q)}
Ba _{1 + r} CuO _{5 + s} phase and RE _{4 (1-q)} Ba
_{2 (1 + r)} Cu ₂ O _{2 (5 + s)} phase means that q, r, and s are -0.3 <q <0.3, -0.3 <r <0.
This is a phase in which one or more phases have a value in the range of 3, -0.5 <s <0.5. ) 7. The RE according to claim 1, wherein
-Ba-Cu-O-based oxide superconductor containing 1 to 60 wt% of an Ag element
-Cu-O based oxide superconductor. 8. The RE according to claim 1, wherein
-Ba-Cu-O based oxide superconductor, Pt, P
A RE-Ba-Cu-O-based oxide superconductor comprising 0.05 to 5 wt% of one or more of d, Ru, Rh, Ir, Os, Re, and Ce. 9. A heat treatment of a raw material mixture containing an RE compound (RE is one or more rare earth metal elements containing Y), a Ba compound and a Cu compound at least in a temperature range higher than the melting point of the raw material mixture. RE-Ba-C having a process of crystal-growing an oxide superconductor phase containing a RE _1-x Ba _{2 + y} Cu ₃ O _d phase after performing a process including
In the method for producing a uO-based oxide superconductor, the oxygen partial pressure at the time of performing the process of crystal-growing the oxide superconductor phase including the RE _1-x Ba _{2 + y} Cu ₃ O _d phase is determined by the following method. A method for producing a RE-Ba-Cu-O-based oxide superconductor, wherein the method is performed differently from the oxygen partial pressure in the previous step. 10. The RE—Ba—Cu—O according to claim 9.
In the method for producing an oxide-based superconductor, Pt, Pd, Ru, Rh, Ir, Os, R
e, a metal of Ce, or one or more elements of these compounds is added in an amount of 0.05 to 5 wt% (in the case of a compound, indicated by the element weight of the metal alone).
A method for producing an E-Ba-Cu-O-based oxide superconductor. 11. The method for producing a RE—Ba—Cu—O-based oxide superconductor according to claim 9, wherein a metal or a compound of Ag is further added to the raw material mixture.
A method for producing a RE-Ba-Cu-O-based oxide superconductor, comprising adding 60 wt% (in the case of a compound, the element weight of Ag alone).