JP2003095653A - Oxide superconductor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curved oxide superconductor excellent in electric characteristics, magnetic characteristics, and mechanical strength, and a method for manufacturing an oxide superconductor capable of manufacturing such an oxide superconductor at low cost. . SOLUTION: 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 at a temperature higher than the melting point of the raw material mixture. Later, in a method of manufacturing an RE-Ba-Cu-O-based oxide superconductor by growing crystals by slow cooling, pellet pieces (12, 23, 33) arranged with steps in a predetermined shape Via a molding (11, 21, 3) on an alumina substrate (12, 22, 32)
1) or a compact is placed on an alumina substrate curved into a predetermined shape via a pellet piece, and after heating and melting the compact, a seed crystal (14, 34) is set and temperature is set. Hold and slowly cool and allow to crystallize.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide superconductor and a method for manufacturing the same, and more particularly to an RE-based oxide superconductor used in bulk magnets, magnetic bearings, current leads, magnetic shields, current limiting devices and the like. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, RE compounds, Ba compounds and C
The raw material mixture containing the u compound is heated and melted at a temperature equal to or higher than the melting point of the raw material mixture, and then a slow cooling step is performed while a temperature gradient is applied to grow a crystal.
As a method for producing an a-Cu-O-based oxide superconductor,
The precursor is molded into a plate shape, the precursor is melted, and then the seed crystal is placed on top of the precursor at a temperature immediately before crystallization, and then the temperature is maintained or gradually cooled to form a seed crystal. A method for producing a reflected flat plate-like oriented crystal is known.

[0003]

However, in the above-mentioned conventional method, for example, in order to form a cylindrical magnetic bearing having a strong radial supporting force, a flat plate-shaped material is divided into circles. Must be processed into a curved shape in an arc,
The amount of grinding process becomes large, and there are problems such as deterioration and reduction in yield.

Further, in order to sufficiently generate magnetic repulsion and attractive force with a rare earth-based permanent magnet while maintaining an appropriate gap, a trapping magnetic field characteristic of about 1T is required, but a conventional material is used. Then, when the surface is processed so as to be curved with a radius of curvature of 80 mm or less, there is a problem that only trapping magnetic field characteristics of about 0.5 T can be obtained due to generation of microcracks.

Therefore, in view of such conventional problems, the present invention provides a curved oxide superconductor excellent in electrical characteristics, magnetic characteristics, and mechanical strength, and a high yield of such oxide superconductor at low cost. An object is to provide a method for producing an oxide superconductor that can be produced.

[0006]

Means for Solving the Problems As a result of earnest research to achieve the above-mentioned objects, the present inventors have found that RE compounds (RE is Y
A raw material mixture containing one or more rare earth metal elements containing Al), a Ba compound and a Cu compound is heated and melted at a temperature higher than the melting point of the raw material mixture, and then slowly cooled to grow crystals. In the method for producing a RE-Ba-Cu-O-based oxide superconductor by the above, the raw material mixture is formed into a plate shape to form a formed body, and the height of the upper surface of the substrate is made nonuniform. The molded body is placed on the substrate via the inclusions placed in the substrate, and the molded body is heated and melted to bend it, and then gradually cooled to grow crystals, thereby obtaining electrical characteristics, magnetic characteristics, and mechanical strength. Excellent curved RE-Ba-Cu-
The inventors have found that an O-based oxide superconductor can be manufactured with high yield and at low cost, and have completed the present invention.

That is, the method for producing an oxide superconductor according to the present invention comprises a raw material mixture containing a RE compound (RE is one or more rare earth metal elements containing Y), a Ba compound and a Cu compound, In the method for producing an RE-Ba-Cu-O-based oxide superconductor by heating and melting at a temperature higher than the melting point of this raw material mixture, and then gradually cooling it to grow crystals, the raw material mixture is formed into a plate shape. To form a molded body, and the molded body is placed on the substrate through an interposition that is arranged on the substrate so that the height of the upper surface becomes uneven,
It is characterized in that the molded body is heated and melted to be curved, and then gradually cooled to grow crystals.

In this method for producing an oxide superconductor,
As the substrate, a flat substrate or a substrate having a curved upper surface can be used. When a flat substrate is used, a floor board containing at least one compound of RE compound, Ba compound and Cu compound as an inclusion is used.
When a substrate having a curved upper surface is used, one of RE compound, Ba compound and Cu compound is used as an inclusion.
Preference is given to using bedding boards or powders which contain one or more compounds.

In the method for producing an oxide superconductor, the molded body may be heated and melted to be curved, and then a seed crystal may be placed on the molded body, followed by gradual cooling for crystal growth. . Alternatively, after heat-melting and bending the molded body, a temperature gradient of 1 to 30 ° C./cm is applied to the upper and lower sides of the molded body so that the upper side of the molded body is on the low temperature side, and then a seed crystal is installed. After that, the molded body may be gradually cooled to grow crystals.

Furthermore, in the method for producing this oxide superconductor,
The temperature at which the compact is heated and melted
_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O_5-yPhase
And RE _{4 + r}Ba_{2 + s}(Cu_1-dAg_d )_TwoO
_10-yPhase (-0.2≤r≤0.2, -0.2≤s≤
0.2, 0 ≦ d ≦ 0.05, −0.2 ≦ y ≦ 0.2)
It is preferable to have a temperature at which at least one phase is in the liquid phase.
Yes.

The oxide superconductor according to the present invention has R
_{E 1 + p Ba 2 + q} (Cu 1-b Ag b) 3 O
_7-x (RE is one or more rare earth metal elements,
−0.2 ≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2, 0 ≦ b
≦ 0.05, −0.2 ≦ x ≦ 0.6) phase, RE
_{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ) O _5-y phase and RE _{4+ r} Ba _{2 + s} (Cu _1-d Ag _d ) ₂ O
_10-y phase (-0.2≤r≤0.2, -0.2≤s≤
0.2, 0 ≦ d ≦ 0.05, −0.2 ≦ y ≦ 0.2) in an oxide superconductor in which at least one phase is finely dispersed, and at least a part of the surface of the oxide superconductor. Is curved to have a radius of curvature of 80 mm or less, and 1T
It is characterized by having the above trapping magnetic field characteristics.

In this oxide superconductor, it is preferable that the oxide superconductor contains 8 wt% to 60 wt% of Ag. Further, the oxide superconductor is Pt, Pd, Ru, R.
One or more kinds selected from metals of h, Ir, Os, Re, Ce and compounds of these metals are used in an amount of 0.05 wt% to 5%.
It is preferable to include wt% (in the case of a compound, it is indicated by the element weight of only the metal). Furthermore, RE is Nd, Sm, G
It is preferable to contain at least 50% of one or more elements selected from d and Dy.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Manufacture of an oxide superconductor according to the present invention
In an embodiment of the fabrication method, a RE compound (RE comprises Y
One or more rare earth metal elements) and Ba compounds
The raw material mixture containing a Cu compound is melted.
After melting by heating at a temperature higher than the point, it is slowly cooled to form crystals.
By increasing the length of the RE-Ba-Cu-O-based oxide
In the method of manufacturing an electric conductor, the raw material mixture is formed into a plate shape.
Shaped to make a molded body, RE compound, Ba compound and Cu
Height of top surface containing one or more of the compounds
Through the floor plate placed on the substrate so that the
And place the molded body on the substrate._{2 + r}
Ba_{1 + s}(Cu_1-dAg_d) O_5-yPhase and RE
_{4 + r}Ba_{2 + s}(Cu_1-dAg_d )_TwoO_10-y
Phase (-0.2≤r≤0.2, -0.2≤s≤0.2, 0
≦ d ≦ 0.05, −0.2 ≦ y ≦ 0.2)
The temperature at which one phase becomes liquid phase or above Tm (preferably Tm +
Melting the molded body in the range of 50 ° C. to Tm + 200 ° C.,
Bend the molded body along the steps of the floorboard, and then
RE by the peritectic reaction of these phases_{1 + p}Ba_{2 + q}(Cu
_1-bAg_b)_ThreeO_7-xImmediately before the temperature Tm at which the phase crystallizes
Gradually cool from (preferably Tm + 20 ℃ to Tm + 0 ℃)
The upper and lower sides of the compact so that the top of the compact is on the low temperature side.
After applying a temperature gradient, place a seed crystal on top of the compact.
And then RE_{1 + p}Ba _{2 + q}(Cu_1-bA
g_b)_ThreeO_7-xTemperature slightly lower than the temperature at which the phase crystallizes
(Preferably from Tm-2 ° C to Tm-20 ° C)
Temperature to maintain the temperature,
Crystals are grown in the horizontal direction and then gradually cooled
The crystals are grown from top to bottom.

RE compound, Ba compound, and C as a floor board
When a floorboard containing one or more compounds of the u compound is used, an impurity element may enter the molded body from the substrate side,
It is possible to suppress the composition deviation of the molded body.

When a substrate curved with a predetermined curvature is used as the substrate on which the molded body is placed, the curvature of the oxide superconductor to be manufactured can be precisely controlled. In this case, powder containing one or more compounds of the RE compound, the Ba compound and the Cu compound may be used instead of the floor plate. Also, as this substrate, alumina, magnesia,
It is possible to use a ceramic substrate such as zirconia or a substrate made of a metal having a melting point higher than that of the molded body. Further, if a material prepared by melting and crystallizing a raw material mixture prepared by using RE compounds, Ba compounds and Cu compounds as raw materials and adding Ag or Pt as needed to adjust to a predetermined composition is used, It is possible to suppress the entry of impurities and enhance the electromagnetic characteristics on the curved surface.

Further, a seed crystal is placed at the center of the upper surface of a material having a concave upper surface, and a predetermined supercooling degree and a temperature gradient are applied to maintain the temperature, so that the material having a concave upper surface has good crystallinity. The material can be obtained.

Further, the molded body is RE _{2 + r} Ba _{1 + s} (C
u _1-d Ag _d ) O _5-y phase and RE _{4 + r} Ba
_{2 + s} (Cu _1-d Ag _d ) ₂ O _{10-y At} least one of the phases and the temperature Tm at which it becomes a liquid phase (RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) when the temperature is lowered from the molten state)
_The same as the crystallization temperature of the ₃ O _7-x phase) is the temperature as shown in FIG. 1 when each rare earth element is used, and when Ag is added, the temperature is based on each temperature. , Ag
As shown in FIG. When a plurality of rare earth elements are mixed, the temperature is the value shown in FIG. 1 multiplied by the molar ratio of each rare earth element and added.

According to such a method, it is possible to manufacture a curved oxide superconductor having excellent electromagnetic characteristics and a predetermined curvature without causing deterioration due to processing such as grinding and reduction in yield. Further, even when a part of the surface is curved to have a radius of curvature of 80 mm or less, it becomes possible to obtain an oxide superconductor having a maximum trapped magnetic flux density characteristic of 1 T or more on the surface having the curvature.

In addition, the RE-Ba-Cu-O-based oxide
In the conductor, RE is selected from Nd, Sm, Gd and Dy.
At least 50% or more of one or two or more elements
Including the above, RE_{1 + p}Ba_{2 + q}(Cu_1-bAg
_b)_ThreeO_7-xRE dispersed in phase_{2 + r}Ba
_{1 + s}(Cu_1-dAg_d) O_5-yPhase and RE
_{4 + r}Ba _{2 + s}(Cu_1-dAg_d )_TwoO_10-y
RE of phase_{2 + r}Ba_{1 + s}(Cu_{1 -D}Ag_d) O
_5-yPhase and RE_{4 + r}Ba_{2 + s}(Cu_1-dA
g_d )_TwoO_10-yThe molar ratio to the phase is 1: 0.3
If less, the critical current density characteristics in high magnetic fields
And the crystallinity in the thickness direction can be made uniform.

Further, when Ag is contained in an amount of 5 wt% or more, Ag becomes RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ).
_It is finely dispersed in the ₃ O _7-x phase to improve the mechanical strength, and the composition deviation in the vertical direction is suppressed, so that a larger oxide superconductor with less crystal defects can be manufactured. In particular, when the added amount of Ag is about 15 wt% ± 5 wt%, the crystal growth temperature is stable and the material with the highest characteristics can be obtained. On the other hand, when Ag is contained in an amount of 60 wt% or more, the volume fraction of the superconductor is too low and the characteristics such as the critical current density are deteriorated.

Further, the above oxide superconductor is Pt,
One or more selected from the metals of Pd, Ru, Rh, Ir, Os, Re and Ce and compounds of these metals are used in an amount of 0.0
If it is contained in an amount of 5 to 5 wt% (in the case of a compound, it is indicated by the element weight of only that metal), RE _{2 + r} Ba _{1 + s} (C
u _1-d Ag _d ) O _5-y phase and RE _{4 + r} Ba
_{2 + s (Cu 1-d} Ag d) 2 O 10-y phase the effect of the fine.

[0022]

EXAMPLES The oxide superconductor and the method for producing the same according to the present invention will be described in detail below based on examples.

[Example 1] Sm_TwoO_Three, BaCO_Three, C
uO raw material powders were mixed with Sm: Ba: Cu = 1.4: 2.
After weighing so as to be 2: 3.2, BaCO_ThreeAnd Cu
Ba only O for 30 hours at 880 ° C._TwoWhen
A calcined powder of CuO was obtained (BaCuO in molar ratio). _Two: CuO
= 2.2: 1.0). Next, weigh this calcined powder in advance.
Sm saved _TwoO_ThreeAnd Pt powder (average particle size 0.01μ
m) and Ag_TwoO powder (average particle size 13.8 μm)
Pt content 0.42 wt%, Ag content 15 wt%
And mix until it becomes 10 minutes at 900 ° C in the air.
Fired for a while. This calcined powder is crushed with a raikai machine and averaged
The particle size was about 2 μm.

When the composition of the obtained calcined powder was analyzed, the values were as shown in FIG. Moreover, when the obtained calcined powder was analyzed by powder X-ray diffraction, it was found that Sm _{1 + p} B
_{a 2+ q (Cu 1-b} Ag b) 3 O 7-x phase and Sm
_{2 + r Ba 1 + s (} Cu 1-d Ag d) O 5-r phase was confirmed. Here, Tm is calculated from FIG. 1 and FIG. 2, and is 1060-40 = 1020 degreeC.

The synthetic powder produced in this way is put in the vertical direction 60
mm, the width 39 mm, and the thickness 25 mm were pressed into a flat plate to prepare a molded body 11. Next, as shown in FIG.
39 mm long and 13 m wide prepared on the alumina substrate 12 in advance by using a raw material having the same composition as that of the molded body 11 in the same process as the melt crystallization step of the molded body 11 described later.
A plurality of pellet pieces 13 having a thickness of about 2 mm and a thickness of about 2 mm are stacked at a predetermined interval so as to be substantially parallel to each other and have substantially the same height. I laid it down. Then, the molded body 11 is placed on the pellet pieces 13 stacked on both sides,
The parts on both sides in the longitudinal direction (longitudinal direction) of the bottom surface of the molded body 11 are supported by the pellet pieces 13 of substantially the same height, which are stacked on both sides, and are installed in a two-zone type furnace body to perform the following steps. went.

First, the temperature was raised from room temperature to 1100 ° C. in 70 hours and kept at this temperature for 20 minutes to obtain Sm _{2 + r} B
a _{1 + s} (Cu _1-d Ag _d ) O _{5-y By} making a semi-molten state in which a phase and a liquid phase exist, the substantially central portion in the longitudinal direction of the molded body 11 is supported by the pellet piece 13 having a low height. Thus, the molded body 11 was curved so that the upper surface of the molded body 11 was concave and the lower surface thereof was convex. After that, molded body 1
1 so that the upper part of 1 is on the low temperature side
A temperature gradient of ° C / cm was applied, and the temperature was lowered at 0.4 ° C / min until the temperature of the upper part of the molded body 11 reached 1025 ° C. Next, Pt which was previously prepared by the melting method was added to 0.5
2 mm in length and width, containing 1 wt% and not including Ag, thickness 1 mm
Seed crystal 1 of Nd _1.8 Ba _2.4 Cu _3.4 O _x composition
4 (see FIG. 5) is brought into contact with the center of the upper surface of the molded body 11 which is curved so that the upper surface is concave so that the growth direction is parallel to the c-axis, and the speed is 1025 ° C. to 1 ° C./hr. The temperature was lowered to 1015 ° C. After holding at this temperature for 60 hours, it is gradually cooled to 945 ° C. over 70 hours, and then the lower part of the molded body 11 is heated to 945 ° C. for 20 hours so that the upper and lower temperature gradients become 0 ° C./cm. Cool, then
Crystallization was performed by gradually cooling to room temperature over 100 hours.

The material crystallized in this way was placed in another furnace capable of gas replacement and annealed as follows. First, the inside of the furnace was evacuated to 0.1 Torr by a rotary pump, and then oxygen gas was flown into the furnace to create an atmospheric pressure atmosphere with an oxygen partial pressure of 99% or more. Thereafter, while flowing oxygen gas at a flow rate of 0.5 L / min in the furnace, the temperature was raised from room temperature to 450 ° C. in 10 hours, and 45
Gradually cool from 0 ℃ to 250 ℃ over 200 hours
The temperature was lowered from 0 ° C. to room temperature in 10 hours. Then, the same annealing treatment was performed once again.

After this annealing treatment, a molded body 1 having a concave upper surface and a convex lower surface as shown in FIG.
No. 1 had a length of 50 mm, a width of 33 mm, and a thickness of 20 mm due to shrinkage, and the upper surface had a radius of curvature of about 60 mm and the lower surface had a radius of curvature of about 80 mm. When this molded body 11 was cut near the center in the vertical direction and the cross section was observed with EPMA, it was found that Sm _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃ O.
Sm _{2 + r} Ba of about 0.1 to 30 μm in the _7-x phase
_{The 1 + s} (Cu _1-d Ag _d ) O _5-y phase was finely dispersed. Here, p, q, r, s, and y are −0.
The value was 2 to 0.2, and x was the value from -0.2 to 0.6. Further, b and d have a value of 0.0 to 0.05, and are about 0.008 on average. Further, Ag of about 0.1 to 100 μm was finely dispersed throughout the entire sample. In addition, pores having a particle size of about 5 to 200 μm were dispersed and existed. Also, the entire material reflects the seed crystal,
As shown in FIG. 5, the crystals are uniformly oriented so that the central thickness direction is parallel to the c-axis, and the misalignment between the adjacent crystals is 3
The temperature was at most 0 °, and a superconducting material having a substantially single crystal form was obtained.

Next, an external magnetic field 2 is formed parallel to the thickness direction of the center.
After cooling from room temperature to 77K while adding T (Tesla), the magnetic field was removed and the magnetic flux density trapped in the superconductor was measured. In this measurement, the Hall element was attached to the XY stage and moved along the concave surface of the superconductor at a distance of about 1 mm from the surface of the superconductor, and the magnetic flux density distribution of the component perpendicular to the thickness direction of the center was measured. I went by. As a result, as shown in FIG. 6, a uniform magnetic field distribution was shown, the maximum trapping magnetic field was 1.2 T, and high trapping magnetic flux density characteristics were shown.

Next, 2.5 × from near the center of this material
A 2.5 × 2 mm sample was cut out and the magnetic susceptibility was measured by an SQUID magnetometer. Be from the obtained magnetic susceptibility curve
When an an model was applied to estimate the critical current density Jc at a temperature of 77K, a high critical current density was shown as shown in FIG. 7.

[Embodiment 2] Gd_TwoO_Three, BaCO_Three, C
uO raw material powders were changed to Gd: Ba: Cu = 1: 2: 3
So that it is weighed, then mixed and baked at 920 ° C for 30 hours
did. This baked powder is then used in a pot mill
Grind to an average particle size of 3 μm and fire again at 930 ° C for 30 hours
After crushing, crush it to an average particle size of 10 μm with a raikai machine.
Gd₁Ba_TwoCu_ThreeO_7-xPowder was prepared. Well
In addition, each of the above raw material powders is Gd: Ba: Cu = 2: 1: 1
And then mix and mix at 890 ° C for 20 hours.
Baked. Then use this baked powder in a pot mill
And crushed to an average particle size of 0.7 μm, and again at 890 ° C for 20
After firing for an hour, use this pot powder in a pot mill.
Crushed to an average particle size of 0.5 μm and Gd_TwoBaCuO₅
Powder was prepared. Next, these calcined powders are Gd₁Ba
_TwoCu_ThreeO_7-x: Gd_TwoBaCuO₅= 1: 0.4
So that Pt powder (average particle size 0.01
μm) and Ag _TwoO powder (average particle size 13.8 μm)
Pt content 0.42 wt%, Ag content 15 wt%
And mixed. Here, Tm is as shown in FIG.
And calculated from FIG. 2, at 1030-40 = 990 ° C.
is there.

The synthetic powder produced in this manner is put in a vertical direction 60
mm, the width 39 mm, and the thickness 25 mm were pressed into a flat plate to prepare a molded body 21. Next, as shown in FIG.
The upper surface of an alumina block having a length of 60 mm, a width of 40 mm, and a thickness of 15 mm is curved in the longitudinal direction (vertical direction) (curvature radius 60
mm) and is formed on an alumina substrate 22 having a concave upper surface by a raw material having the same composition as that of the molded body 21 in advance by a process similar to the melt crystallization process of the molded body 21 described later. A plurality of pellets 23 having a length of 39 mm, a width of 6 mm, and a thickness of about 2 mm are spread on an alumina substrate 22 having a concave upper surface, the molded body 21 is placed on the alumina substrate 22, and the bottom surface of the molded body 21 The pellets 23 were supported on both sides in the longitudinal direction (longitudinal direction), and the pellets 23 were installed in a 2-zone type furnace, and the following steps were performed.

First, the temperature is raised from room temperature to 1100 ° C. in 70 hours, maintained at this temperature for 20 minutes to be in a semi-molten state, and the pellet 21 is inserted along the concave surface of the alumina substrate 22 to form the compact 21. The molded body 21 was curved so that the upper surface was concave and the lower surface was convex. Next, the top and bottom of the molded body 21 are placed at 10 ° C. /
When a temperature gradient of cm is applied, the temperature of the upper part of the molded body 21 becomes 9
The temperature was lowered at 0.4 ° C / min until the temperature reached 95 ° C. Next, Nd of 0.5 mm in width and 2 mm in length and width, containing 0.5 wt% of Pt and having a thickness of 1 mm, which was prepared in advance by a melting method.
_1.8 Ba _2.4 Cu _3.4 O _x composition (not shown)
The seed crystal is formed into a compact 2 with the growth direction parallel to the c-axis.
1 was brought into contact with the center of the upper surface, and the temperature was lowered from 995 ° C. to 985 ° C. at a rate of 1 ° C./hr. After holding at this temperature for 80 hours, it is gradually cooled to 915 ° C. over 70 hours, and thereafter, the molded body 2 is adjusted so that the upper and lower temperature gradients become 0 ° C./cm.
The lower part of 1 was cooled to 915 ° C. in 20 hours, and then gradually cooled to room temperature over 100 hours for crystallization.

The material crystallized in this manner was placed in another furnace capable of gas replacement and annealed as follows. First, the inside of the furnace was evacuated to 0.1 Torr by a rotary pump, and then oxygen gas was flown into the furnace to create an atmospheric pressure atmosphere with an oxygen partial pressure of 99% or more. Thereafter, while flowing oxygen gas at a flow rate of 0.5 L / min in the furnace, the temperature was raised from room temperature to 450 ° C. in 10 hours, and 45
Gradually cool from 0 ℃ to 250 ℃ over 200 hours
The temperature was lowered from 0 ° C. to room temperature in 10 hours. Then, the same annealing treatment was performed once again.

After this annealing treatment, the molded body 21 curved so that the upper surface is concave and the lower surface is convex has a length of 50 mm, a width of 33 mm and a thickness of 20 mm due to shrinkage.
The radius of curvature of the upper surface is about 60 mm, and the radius of curvature of the lower surface is about 80 mm.
It was mm. When this molded body 21 was cut near the center in the vertical direction and the cross section was observed by EPMA, it was found that Gd _{1+ p
Ba 2 + q (Cu 1-} b Ag b) 3 O 7-x 0 in phase.
Gd _{2 + r} Ba _{1 + s} (Cu _{1-d of} about _{1 to} 30 μm ₎
The Ag _d ) O _5-y phase was finely dispersed. here,
p, q, r, s, and y each had a value of -0.2 to 0.2, and x had a value of -0.2 to 0.6. Also, b,
d is a value of 0.0 to 0.05, and is 0.00 on average.
It was about 8. Furthermore, 0.1 to 0.1
Ag of about 100 μm was finely dispersed. In addition, pores having a particle size of about 5 to 200 μm were dispersed and existed.
In addition, the whole material reflects the seed crystal, and the thickness direction of the center is c
A superconducting material which is uniformly oriented so as to be parallel to the axis, has an orientation deviation of 3 ° or less between adjacent crystals, and is substantially a single crystal is obtained.

Next, the external magnetic field 2 is provided parallel to the thickness direction of the center.
After cooling from room temperature to 77K while adding T, the magnetic field was removed and the magnetic flux density trapped in the superconductor was measured. In this measurement, the Hall element was attached to the XY stage and moved along the concave surface of the superconductor at a distance of about 1 mm from the surface of the superconductor, and the magnetic flux density distribution of the component perpendicular to the thickness direction of the center was measured. I went by.
As a result, it shows a uniform magnetic field distribution, and the maximum trapping magnetic field is 1.
It was 2T and showed a high trapping magnetic flux density characteristic.

Next, 2.5 × from near the center of this material
A 2.5 × 2 mm sample was cut out and the magnetic susceptibility was measured by a vibrating sample magnetometer. Be from the obtained magnetic susceptibility curve
When an an model was applied to estimate the critical current density Jc at a temperature of 77K, a high critical current density was shown as shown in FIG.

[Example 3] The synthetic powder produced in the same manner as in Example 1 was press-molded into a flat plate having a length of 60 mm, a width of 39 mm and a thickness of 25 mm to form a molded body 31. Next, as shown in FIG. 10, the molded body 11 is formed on the alumina substrate 32.
39 mm in length and 13 m in width prepared in advance by the same melt crystallization process as in Example 1 using a raw material having the same composition as
A plurality of pellet pieces 33 having a thickness of 2 mm and a thickness of about 2 mm are stacked at a predetermined height, and the pellet pieces 33 are stacked on both sides of the stacked pellet pieces 33 at a predetermined interval in a substantially parallel manner and in the center. It was laid so that it would be low. Next, the molded body 31 was placed on the pellet pieces 33 stacked in the center, and the melt crystallization and the annealing treatment were performed in the same manner as in Example 1.

After this annealing treatment, as shown in FIG. 11, the molded body 31 having a convex upper surface and a concave lower surface has a length of 50 mm, a width of 33 mm, and a thickness of 20 mm due to shrinkage. The radius of curvature of the upper surface was about 80 mm, and the radius of curvature of the lower surface was about 60 mm. When this molded body 31 was cut near the center in the vertical direction and the cross section was observed by EPMA, the structure was almost the same as in Example 1. In addition, the entire material is uniformly oriented so that the central thickness direction is parallel to the c-axis, reflecting the seed crystal, and the misalignment between the adjacent crystals is 3 ° or less, and the single crystal is substantially a single crystal. A superconducting material having a shape of a line was obtained.

Next, the external magnetic field 2 is made parallel to the thickness direction of the center.
After cooling from room temperature to 77K while adding T, the magnetic field was removed and the magnetic flux density trapped in the superconductor was measured. In this measurement, the Hall element was attached to the XY stage and moved along the convex surface of the superconductor at a distance of about 1 mm from the surface of the superconductor, and the magnetic flux density distribution of the component perpendicular to the thickness direction of the center was measured. It was done by measuring.
As a result, it shows a uniform magnetic field distribution, and the maximum trapping magnetic field is 1.
It was 2T and showed a high trapping magnetic flux density characteristic.

Next, 2.5 × from near the center of this material
A 2.5 × 2 mm sample was cut out and the magnetic susceptibility was measured by an SQUID magnetometer. Be from the obtained magnetic susceptibility curve
When the an model was applied to estimate the critical current density Jc at a temperature of 77 K, the critical current density was as high as in Example 1.

[Comparative Example] A synthetic powder produced by the same method as in Example 1 was used to measure length 60 mm, width 39 mm, and thickness 33 m.
m was pressed into a flat plate to prepare a molded body. next,
Plural pieces of pellets having a length of 39 mm, a width of 13 mm, and a thickness of about 2 mm, which were prepared in advance by the same melt crystallization process as in Example 1 using the raw material having the same composition as that of the molded body, were placed on an alumina substrate. It was spread evenly, the molded body was placed on it, and it was placed in a two-zone type furnace body, and the following steps were performed.

First, the temperature was raised from room temperature to 1100 ° C. in 70 hours and kept at this temperature for 20 minutes to obtain Sm _{2 + r} Ba.
_{1 + s} (Cu _1-d Ag _d ) O _5-y phase and liquid phase were in a semi-molten state. Then, a temperature gradient of 10 ° C./cm is applied to the top and bottom of the compact so that the upper part of the compact is on the low temperature side, and the temperature of the upper part of the compact is 0.45 until the temperature of the upper part reaches 1025 ° C.
The temperature was lowered at ° C / min. Next, Nd _1.8 Ba _2.4 Cu having a width of 2 mm and a thickness of 1 mm containing 0.5 wt% Pt and not containing Ag, which has been prepared in advance by a melting method.
A seed crystal having a composition of _3.4 O _x was brought into contact with the center of the upper surface of the compact so that the growth direction was parallel to the c-axis, and the temperature was lowered from 1025 ° C. to 1015 ° C. at a rate of 1 ° C./hr. After holding at this temperature for 60 hours, it is slowly cooled to 945 ° C over 70 hours, and then the lower part of the molded body is cooled to 945 ° C in 20 hours so that the upper and lower temperature gradients become 0 ° C / cm. Then, crystallization was performed by gradually cooling to room temperature over 100 hours.

The material crystallized in this way was placed in another furnace capable of gas replacement and annealed as follows. First, the inside of the furnace was evacuated to 0.1 Torr by a rotary pump, and then oxygen gas was flown into the furnace to create an atmospheric pressure atmosphere with an oxygen partial pressure of 99% or more. Thereafter, while flowing oxygen gas at a flow rate of 0.5 L / min in the furnace, the temperature was raised from room temperature to 450 ° C. in 10 hours, and 45
Gradually cool from 0 ℃ to 250 ℃ over 200 hours
The temperature was lowered from 0 ° C. to room temperature in 10 hours. Then, the same annealing treatment was performed once again.

After this annealing treatment, the compact had a length of 50 mm, a width of 33 mm and a thickness of 26 mm due to shrinkage.

When this molded body was cut near the center in the vertical direction and the cross section was observed by EPMA, the structure was almost the same as in Example 1. In addition, the entire material is uniformly oriented so that the thickness direction is parallel to the c-axis, reflecting the seed crystal, and the misalignment between adjacent crystals is 3 ° or less. A superconducting material was obtained.

Next, the material on the flat plate was ground to a length of 50 mm, a width of 33 mm, a thickness of 20 mm, a radius of curvature of the upper surface of 60 mm, and a radius of curvature of the lower surface of 80 mm. Similarly, the magnetic flux density trapped in the superconductor was measured. As a result, the maximum trapping magnetic field was as low as 0.5 T due to deterioration due to grinding.

[0048]

As described in detail above, according to the present invention,
A molded body is placed on a substrate through an inclusion that is arranged with a step in a predetermined shape, or a molded body is placed on a substrate that is curved into a predetermined shape through an inclusion, By melting and crystallizing, the electric characteristics, magnetic characteristics, and
A curved oxide superconductor having excellent mechanical strength can be manufactured at low cost.

[Brief description of drawings]

[1] _RE 1 ₊ p _{Ba 2 +} q in the case of using the rare earth element as a _{RE (Cu 1 -b Ag b)} 3 O 7-x
The figure which shows melting | fusing point (crystallization temperature) Tm of a phase.

FIG. 2 shows the amount of Ag added and RE _{1 + p} Ba _{2 + q} (Cu
_1-b Ag _b ) ₃ O _7-x phase melting point (crystallization temperature) Tm
FIG. 6 is a diagram showing a relationship with the correction value of.

FIG. 3 is a view showing the composition of the molded body produced in Example 1.

FIG. 4 is a perspective view showing a method of placing the molded body of Example 1.

FIG. 5 is a perspective view showing a molded body of Example 1 after crystallization.

FIG. 6 is a diagram showing trapped magnetic flux density distribution characteristics of the oxide superconductor manufactured in Example 1.

FIG. 7 is a diagram showing the magnetic field dependence of the critical current density of the oxide superconductor manufactured in Example 1.

FIG. 8 is a perspective view showing a method of placing the molded body of the second embodiment.

9 is a diagram showing the magnetic field dependence of the critical current density of the oxide superconductor produced in Example 2. FIG.

FIG. 10 is a perspective view showing a method of mounting the molded body of Example 3.

FIG. 11 is a perspective view showing a molded body of Example 3 after crystallization.

[Explanation of symbols]

11, 21, 31 molded products 12, 22, 32 Alumina substrate 13, 23, 33 pellet pieces 14,34 seed crystals Lines indicating the planes along the ab plane of crystals

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 39/24 H01L 39/24 B (72) Inventor Shigeo Nagaya Kita Otakamachi, Midori-ku, Nagoya-shi, Aichi Sekiyama 20 No. 1 Chubu Electric Power Co., Inc. Electric Power Technology Research Institute F-term (reference) 4G047 JA03 JA04 JB03 JB06 JC02 KC01 KC06 KD10 LA01 LB01 LB04 4G077 AA02 BC53 CC03 EC05 4M113 AD36 BA21 BA29 CA34 5G321 AA01 BA02 BA03 BA05 BA11 DB11 BA05 BA11 DB28

Claims (13)

[Claims] 1. RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag
_b ) ₃ O _7-x (RE is one or more rare earth metal elements, -0.2≤p≤0.2, -0.2≤q≤0.
2, 0 ≦ b ≦ 0.05, −0.2 ≦ x ≦ 0.6) phase, RE _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ) O.
_5-y phase and RE _{4 + r} Ba _{2 + s} (Cu _1-d A
g _d ) ₂ O _10-y phase (−0.2 ≦ r ≦ 0.2, −
0.2 ≦ s ≦ 0.2, 0 ≦ d ≦ 0.05, −0.2 ≦ y
≤0.2) in an oxide superconductor in which at least one phase is finely dispersed, at least a part of the surface of the oxide superconductor is curved to have a radius of curvature of 80 mm or less, and capture of 1 T or more. An oxide superconductor characterized by having magnetic field characteristics. 2. The oxide superconductor is 8 wt% to 6%.
The oxide superconductor according to claim 1, wherein the oxide superconductor contains 0 wt% Ag. 3. The oxide superconductor is Pt, Pd, R.
0.05 wt% of one or more selected from metals of u, Rh, Ir, Os, Re, Ce and compounds of these metals.
3 to 5 wt% (in the case of a compound, it is indicated by the element weight of only the metal), the oxide superconductor according to claim 1 or 2. 4. The RE contains at least 50% of one or more elements selected from Nd, Sm, Gd and Dy.
The oxide superconductor according to any one of claims 1 to 3, comprising the above. 5. A raw material mixture containing a RE compound (RE is one or more rare earth metal elements containing Y), a Ba compound and a Cu compound is heated and melted at a temperature higher than the melting point of the raw material mixture. Then, in the method for producing an RE-Ba-Cu-O-based oxide superconductor by slowly cooling and growing a crystal, in the method, the raw material mixture is formed into a plate to form a formed body, and the upper surface is formed. The molded body is placed on the substrate through inclusions arranged on the substrate so that the height of the molded body becomes uneven, and the molded body is heated and melted to be curved, and then gradually cooled. A method for producing an oxide superconductor, which comprises crystallizing the crystal by means of crystal growth. 6. The method for producing an oxide superconductor according to claim 5, wherein the substrate is a flat substrate. 7. The method for producing an oxide superconductor according to claim 5, wherein the substrate has a curved upper surface. 8. The method for producing an oxide superconductor according to claim 5, wherein the inclusion contains at least one compound selected from a RE compound, a Ba compound and a Cu compound. 9. The method for producing an oxide superconductor according to claim 8, wherein the inclusion is a floor plate. 10. The method for producing an oxide superconductor according to claim 7, wherein the inclusion is a powder containing one or more compounds of a RE compound, a Ba compound and a Cu compound. 11. The method according to claim 5, wherein after the molded body is heated and melted to be curved, a seed crystal is placed on the molded body, and then gradually cooled to grow a crystal.
A method for producing an oxide superconductor according to any one of 1. 12. After heat-melting and bending the molded body, a temperature gradient of 1 to 30 ° C./cm is applied to the upper and lower sides of the molded body so that the upper portion of the molded body is on the low temperature side,
The method for producing an oxide superconductor according to any one of claims 5 to 10, wherein a seed crystal is provided, and then the molded body is gradually cooled to grow a crystal. 13. The temperature for heating and melting the molded body is such that the molded body is RE _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ).
O _5-y phase and RE _{4 + r} Ba _{2 + s} (Cu _1-d A
g _d ) ₂ O _10-y phase (−0.2 ≦ r ≦ 0.2, −
0.2 ≦ s ≦ 0.2, 0 ≦ d ≦ 0.05, −0.2 ≦ y
≦ 0.2), which is a temperature at which at least one of the phases becomes a liquid phase, and the method for producing an oxide superconductor according to any one of claims 5 to 12, wherein.