JP2001114595A - High temperature oxide superconducting material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-sized oxide superconductor excellent in electric properties, magnetic properties, and mechanical strength, and a method of manufacturing such an oxide superconductor at low cost and with good reproducibility. I will provide a. SOLUTION: It contains RE (RE is one or more rare earth metal elements including Y), Ba and Cu as constituent elements, and has a growth rate of 0.1 mm / h / ° C or less or 0.5 m.
RE _{1 + p} Ba _{2 + q} (Cu _1-b A
g _b ) ₃ O _{7 -x} (−0.2 ≦ p ≦ 0.2, −0.2 ≦ q
≤ 0.2, 0 ≤ b ≤ 0.05, -0.2 ≤ x ≤ 0.6) A first compact containing a phase, RE, Ba and Cu as constituent elements, and a growth rate of 0.2. Greater than 1 mm / h / ° C and
RE _{1 + p} Ba _{2 + q} (Cu less than 5 mm / h / ° C.
_{1-b Ag b) 3 O} 7-x phase by laminating a second shaped body _{containing, RE 1 + p Ba 2 +} q (Cu 1-b Ag b) 3
After firing at a temperature equal to or higher than the melting point of the O _7-x phase, a seed crystal is placed on the side of the second molded body, and the second crystal is gradually cooled or maintained at a temperature to maintain the second crystal.
The oxide superconductor is manufactured by crystallizing from the molded body side to the first molded body side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oxide superconductor and a method of manufacturing the same, and more particularly to an oxide superconductor used for a current lead, a magnetic bearing, a magnetic shield, a bulk magnet, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, RE compounds (RE is one or more rare earth metal elements containing Y (yttrium)),
After heating and melting a raw material mixture containing a Ba compound and a Cu compound to a temperature higher than the melting point of the raw material mixture, a crystal is grown by performing a slow cooling step while applying a temperature gradient, whereby RE-Ba-Cu As a method for producing a -O-based oxide superconductor, for example, Japanese Patent Application Laid-Open No. 10-53415
Is known. This method uses the RE
The compound, Ba compound and Cu compound are mixed with Ag and Pt in a predetermined ratio and fired. The obtained fired powder is molded, melted, and the REBaCuO crystal to which Ag is not added is placed as a seed crystal. This is a method for producing an oriented RE-Ba-Cu-O-based oxide superconductor having a high critical current density by performing a slow cooling step in a temperature gradient to cause crystallization.

[0003]

SUMMARY OF THE INVENTION However, the conventional
In the method, when the crystal is enlarged, the RE_{1 + p}Ba<sub>2
+ Q</sub>(Cu_1-bAg_b)₃O_7-xIn ab plane of phase crystal
Micro cracks with a width of about 0.1 to 10 μm
And the superconducting current is disrupted, critical current density and magnetization
There is a problem that some parts become smaller
Was. This microcrack can be prevented by adding Ag.
Y-based and other rare earth materials with relatively high mechanical strength
When Ag is added to a mixed system of a class metal element and a Y system,
The growth rate is as low as about 0.1 mm / h / ° C or less.
It takes a long time to grow crystals when manufacturing large
Costly and, in addition, RE_{2 + r}Ba
_{1 + s}(Cu_{1 -D}Ag_d) O_5-yPhase or RE
_{4 + r}Ba_{2 + s}(Cu_1-dAg_d)₂O _10-yphase
And Ag aggregation and coarsening occur, and magnetic properties and mechanical strength properties
However, there is a problem in that the metal is deteriorated.

In the La-based and Nd-based and mixed systems of these elements and other rare earth metal elements, the critical temperature and critical current density characteristics in a high magnetic field are high, but the crystal growth rate is 0.5 mm. / H / ° C. or more, which is too fast, so that nucleation of crystals is likely to occur, and it is difficult to obtain large oriented crystals.

[0005] Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and a large-sized oxide superconductor having excellent electrical characteristics, magnetic characteristics, and mechanical strength, and a reproducible low-cost oxide superconductor. It is an object of the present invention to provide a method of manufacturing an oxide superconductor that can be manufactured well.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that RE compounds (RE compounds)
Is one or more rare earth metal elements containing Y), B
The raw material mixture containing the compound a and the Cu compound is heated and melted to a temperature higher than the melting point of the raw material mixture, and then a crystal is grown by performing a slow cooling step while applying a temperature gradient to thereby obtain RE-Ba-Cu-. In a method of manufacturing an O-based oxide superconductor, a crystal is grown by laminating a material of a system having a growth rate of more than 0.1 mm / h / ° C. and less than 0.5 mm / h / ° C. As a result, RE-B
The inventors have found that an a-Cu-O-based oxide superconducting material can be manufactured in a short time and with good yield, and have completed the present invention.

That is, the method of manufacturing an oxide superconductor according to the present invention includes RE (RE is one or more rare earth metal elements including Y), Ba and Cu as constituent elements, and has a growth rate of 0.5. 1mm / h / ° C or less or 0.5m
a first molded body containing a first phase of m / h / ° C. or more, containing RE, Ba, and Cu as constituent elements, and having a growth rate of more than 0.1 mm / h / ° C. and 0.5 mm / h / And a second compact containing a second phase smaller than
After firing at a temperature equal to or higher than the melting point of the second phase, a seed crystal is placed on the side of the second compact and crystallized from the second compact toward the first compact by slow cooling or maintaining the temperature. The oxide superconductor is thus manufactured.

In the above manufacturing method, the first and second
The phase of RE_{1 + p}Ba_{2 + q}(Cu_1-bAg_b)₃
O_7-x(-0.2 ≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2,
0 ≦ b ≦ 0.05, −0.2 ≦ x ≦ 0.6)
preferable. In the crystallization step, the oxide
The conductor is RE_{1 + p}Ba_{2 + q}(Cu_1-bAg_b) ₃
O_7-x(-0.2 ≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2,
0 ≦ b ≦ 0.05, −0.2 ≦ x ≦ 0.6)
It is preferable to crystallize to. In addition, the first and second
The molded body is made of an RE compound (RE is one or two types including Y
Rare earth metal elements described above), Ba compound and Cu compound
Is manufactured by mixing, baking, pulverizing and molding.
be able to. Also, RE of the first molded body is Y, Nd,
Y_0.5Gd_0.5In the case of, the RE of the second compact is
And it is preferable to use Sm, Sm and Gd respectively.
No. Further, the first and second compacts are 5 wt% to
Preferably, it contains 60 wt% Ag. This Ag is A
An Ag compound of 5 wt% to 60 wt% in g element amount may be used.
Ag or Ag having an average particle size of 0.3 μm to 1.8 μm
Preferably, a compound powder is used. In addition, the first and
And the second compact are Pt, Pd, Ru, Rh, Ir, O
at least one element selected from s and Re.
It is preferable to contain from 05 wt% to 5 wt%, especially Pt.
It is preferred to include.

In the above manufacturing method, the second compact is laminated on the first compact, and in the crystallization step, the temperature is raised and lowered so that the upper portion of the second compact is on the low temperature side. It is preferable to lower the temperature by adding a gradient.

Further, in the above-mentioned production method, Ag-free RE _1.8 Ba _2.4 Cu _3.4 as a seed crystal is used.
O _x composition (RE is one or more rare earth metal elements including Y) is preferable to use seed crystals melt.
Further, it is preferable that the first molded body and the second molded body have the same outer diameter.

Further, the oxide superconductor according to the present invention has an 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 including Y, -0.2≤p≤0.2, -0.2≤q≤0.2, 0
≦ b ≦ 0.05, −0.2 ≦ x ≦ 0.6) phase, in which Ag is finely dispersed in the phase,
It is characterized in that the misorientation of the orientation between adjacent crystals over a length of 40 mm or more and a thickness of 2 mm or more is ± 5 ° or less, preferably ± 1 ° or less.

In the above oxide superconductor, RE
_{1 + p}Ba_{2 + q}(Cu_1-bAg_b) ₃O_7-xAnaka
And RE_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O
_5-yPhase or RE_{4 + r}Ba_{2 + s}(Cu_1-dAg
_d)₂O_10-yPhase (−0.2 ≦ r ≦ 0.2, −0.2 ≦
s ≦ 0.2, 0 ≦ d ≦ 0.05, −0.2 ≦ y ≦ 0.2)
It is preferred to be finely dispersed. Also, the average particle size of Ag
The thickness is preferably 30 μm or less. Furthermore, RE_{2 + r}
Ba_{1 + s}(Cu_1-dAg_d) O_5-yAverage particle size of phase
Is set to 0.5 μm to 3 μm, and RE_{4 + r}Ba
_{2 + s}(Cu_1-dAg_d)₂O _10-yAverage particle size of phase
Is preferably 1 μm to 5 μm.

Further, the laminated body as a material of the oxide superconductor according to the present invention is characterized in that RE (RE is one or more rare earth metal elements containing Y), Ba and C
a first compact including u and a first phase having a growth rate of 0.1 mm / h / ° C. or less or 0.5 mm / h / ° C. or more, and RE and Ba and Cu as constituent elements and growing Rate is greater than 0.1 mm / h / ° C. and 0.5 mm /
and a second compact containing a second phase smaller than h / ° C. In this case, the first and second phases are RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃ O
_7-x (-0.2 ≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2, 0
≤ b ≤ 0.05, -0.2 ≤ x ≤ 0.6).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the method of manufacturing an oxide superconductor according to the present invention, RE (RE is one or more rare earth metal elements containing Y) and Ba are used as constituent elements.
RE _{1 + p} Ba _{2 + q} containing 0.1% / h / ° C. or less and 0.5 mm / h / ° C. or more and containing Cu and Cu
(Cu _1-b Ag _b ) ₃ O _7-x (−0.2 ≦ p ≦ 0.
2, -0.2≤q≤0.2, 0≤b≤0.05, -0.2≤
x ≦ 0.6) A first compact containing a phase, containing RE, Ba, and Cu as constituent elements and having a growth rate of 0.1 mm /
R greater than h / ° C and less than 0.5 mm / h / ° C
E _{1 + p} Ba _{2 + q} (Cu _{1- b} Ag _b ) ₃ O _{7-x A} second compact containing a _7-x phase is laminated, and RE _{1 + p} Ba ₂
After baking at a temperature equal to or higher than the melting point of the _{+ q} (Cu _1-b Ag _b ) ₃ O _7-x phase, a seed crystal is placed on the second compact side, and gradually cooled, and the temperature is kept from the second compact side. An oxide superconductor is manufactured by crystallization toward the first molded body. Thus, RE _{1 + p} Ba _{2 + q} (Cu _{1− b} Ag _b ) _{3 of} the second molded body laminated on the first molded body
The reason why the growth rate of the O _7-x phase is in the range of more than 0.1 mm / h / ° C. and less than 0.5 mm / h / ° C. is as follows.

RE_{1 + p}Ba_{2 + q}(Cu_1-bA
g_b)₃O_7-xThe melting point and crystal growth rate of phase crystals are
It depends on the ionic radius of the RE element, and the ionic radius is large.
The melting point is higher when using a suitable element, and the crystal growth rate is
Be faster. Also, RE_{1 + p}Ba _{2 + q}(Cu_1-bA
g_b-1)₃O_7-xPhase crystal melting point and crystal growth rate
Depends on the amount of Ag added, and the amount of Ag added is increased.
This lowers the melting point and lowers the crystal growth rate. This
Ag addition amount and RE_{1 + p}Ba_{2 + q}(Cu_{1- b}A
g_b)₃O_7-xThe relationship with the melting point of phase crystals is described in
-53415. Also, the degree of supercooling
And RE_{1 + p}Ba_{2 + q}(Cu_1-bAg_b)₃O
_7-xThe relationship between the phase crystal growth rate and RE is Y, Gd,
In the case of Sm and Nd, FIG. 1, FIG. 2, FIG.
4 and that shown in FIG. Also,
These mixed systems are multiplied by the component ratio of each growth rate.
Value. Here, the growth rate changes with respect to the degree of supercooling.
The growth rate is defined as the growth rate (growth rate = growth rate / degree of supercooling)
And the growth rate when the amount of Ag added for each RE is changed
Is calculated as shown in FIG. This growth rate
Is too low, it may be necessary to grow large crystals.
Since it takes a long time, the cost increases. Furthermore, long hours
In the part exposed to the molten state during_{2 + r}Ba
_{1 + s}(Cu_1-dAg_d) O_5-yPhase or RE
_{4 + r}Ba_{2 + s}(Cu_1-dAg_d)₂O_10-yAnd
Ag, etc., agglomerates and coarsens, resulting in significant deterioration of properties.
I will. This is because materials with a slow growth rate
Disordered nucleation of crystals is likely to occur even when supercooling is applied
This is because the yield becomes worse. Ma
Also, the higher the growth rate, the faster the crystal growth rate
Yes, but if this growth rate is too high
Growth rate changes drastically with
Premature nucleation is likely to occur, and the yield decreases. I
Therefore, it is necessary to reduce production time and obtain high yield.
To achieve this, the growth rate should be greater than 0.1 mm / h / ° C. and
It is desirable to make the range smaller than 5 mm / h / ° C.

Also, RE _{1 + p} Ba _{2 + q} (Cu _{1-b
Ag b) 3 O 7-x} RE 2+ during phase r _{Ba 1} + s (Cu
_1-d Ag _d ) O _5-y phase or RE _{4 + r} Ba _{2 + s}
In the case of producing a crystal in which (Cu _1-d Ag _d ) ₂ O _10-y phase is finely dispersed, Ag is added in an amount of 5 to 60 wt% to perform unidirectional solidification, so that 0% in the oriented crystal. .
When Ag of 1 to 100 μm is finely dispersed and its average particle size becomes 30 μm or less, RE _{1 + p} Ba _{2 + q} (Cu
The stress in the _1-b Ag _b ) ₃ O _7-x phase crystal is relaxed,
Generation of micro cracks can be suppressed. At this time, the addition of Ag improves the magnetic properties, mechanical strength, and water resistance. However, if the addition amount of Ag is less than 5 wt%, the effect is low. If the addition amount is more than 60 wt%, the superconducting current becomes difficult to flow and the characteristics are deteriorated. Would. Then, in the cooling step from the molten state, if the time until solidification exceeds 100 hours, Ag agglomeration and coarsening rapidly progress.
When the average particle size of g exceeds 50 μm, the mechanical strength characteristics are significantly deteriorated.

Further, when the melting method is used, Ag is coarsened and coarsened, and RE _{1 + p} Ba _{2 + q} (Cu _1−b Ag _b )
The uniform substitution of Ag at the Cu site in the ₃ O _7-x phase is suppressed, but Ag or a powder of an Ag compound having a particle size of 0.3 μm to 1.8 μm is used for crystallization. When a relatively gentle temperature gradient of about 3 to 8 ° C./cm is added to the crystal to grow the crystal in one direction from the seed crystal at a crystal growth rate of 1.5 to 3 mm / h, coarsening of Ag is suppressed, RE
_{1 + p Ba 2 + q (} Cu 1-b Ag b) 3 O 7 in _-x phase can be 0.005 ≦ b ≦ 0.05 is preferable ranges substitution amount of Ag to Cu sites between crystal It is possible to reduce the small-angle grain boundaries having an inclination of about 1 to 5 ° and to increase the critical temperature (Tc), the critical current density (Jc), and the mechanical strength.

Also, an element having a relatively large ionic radius is selected as RE, and Ag is added thereto to obtain high-quality REBaCu.
When an O-based superconductor is manufactured, the crystal growth rate is necessarily kept low. However, in a process described later, the S layer having a moderate crystal growth rate as the first layer precursor is used.
If an m, Eu, Gd, Dy system or a mixture thereof is selected, the growth rate can be increased and an efficient rate can be obtained that is less likely to be a polycrystal. Therefore, the crystal growth time can be shortened and RE _{2 + r} Ba _{1 + s} can be obtained. (Cu _1-d Ag _d )
O _5-y phase or RE _{4 + r} Ba _{2 + s} (Cu _1-d A
g _{d) 2} O _10- suppressing aggregation coarsening of _y phase and Ag, it is possible to produce a large superconductor at low cost with high performance.

Further, when a laminate composed of the first layer precursor and the second layer precursor having the same diameter is used, the crystal growth rate can be made the same over the entire second layer precursor. Generation of stress can be suppressed and cracks can be reduced.

Further, it is desirable to add at least 5% or more of Ag to the upper precursor to be laminated for the following two reasons. One of the reasons is that when Ag is contained in both precursors, the adhesion of the gap between the laminated precursors when molten is improved, so that nucleation of crystals in different directions and stress in the crystals are caused. This is because generation can be suppressed. Another reason is that if the Ag content in the upper precursor is small, Ag diffuses from the lower portion, and the crystallization temperature of the upper precursor is not stable, so that the precursor tends to be polycrystalline.

Note that Pt, Pd, Ru, Rh, Ir, O
s and Re in the range of 0.05 to 5% by weight of metal or
Are added as compound powders or in these metal crucibles.
When the mixture is mixed by performing a process of preparing a raw material mixture at
E_{2 + r}Ba_{1 + s}(Cu_{1 -D}Ag_d) O_5-yAcquaintance
Or RE_{4 + r}Ba_{2 + s}(Cu_1-dAg_d)₂O
_10-yIt was confirmed that the phase became fine and showed high characteristics.
ing. In addition, when these elements melt, Ag or B
It is confirmed that the same effect can be obtained even when
It has been certified.

[0022]

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

[Embodiment 1] In this embodiment, the growth rate of Y is low.
Material with 20 wt% Ag added to the system (growth rate 0.05)
Ag is added to Sm-based material with fast growth rate
This is an example in which a material (% growth rate: 0.45) with% addition is laminated on the upper portion to grow crystals.

First, RE ₂ O ₃ (in this embodiment, Y ₂ O ₃
And Sm ₂ O ₃ ), BaCO ₃ , and CuO as raw material powders.
E: After weighing Ba: Cu = 1.8: 2.4: 3.4, only BaCO ₃ and CuO were calcined at 880 ° C. for 30 hours to obtain a calcined powder of BaCuO ₂ and CuO. (Molar ratio: BaCuO ₂ : CuO = 2.4: 1.0). next,
This calcined powder is mixed with Y ₂ O ₃ weighed in advance and 0.5 w
t% Pt powder (average particle size 0.01μm) and 20wt%
Ag powder (average particle size 0.45 μm) was mixed and fired at 900 ° C. in the air for 10 hours. Similarly, the above BaC
Sm ₂ weighed in advance on calcined powder of uO ₂ and CuO
O ₃ , 0.5 wt% of Pt powder and 10 wt% of Ag powder were mixed and fired at 900 ° C. in the air for 10 hours. The obtained calcined powder was pulverized with a raikai machine to obtain an average particle size of about 2 μm. When the obtained calcined powder was analyzed by powder X-ray diffraction, it was confirmed that RE _{1 + p} Ba _{2 + q} (Cu
_1-b Ag _b ) ₃ O _7-x phase and RE _{2 + r} Ba
_{A 1 + s} (Cu _1-d Ag _d ) O _5-y phase was confirmed.

Of the synthetic powder thus produced,
For those with RE of Y, outer diameter 80 mm, thickness 25 mm
The precursor 1 was prepared by press molding into a disk shape of
For Sm, precursor 2 was prepared by press-forming into a disk having an outer diameter of 80 mm and a thickness of 10 mm.

Next, as shown in FIG. 6, the precursor 2 is laminated on the top of the precursor 1, placed on an alumina substrate on which Y ₂ O ₃ powder is spread, and placed in a two-zone furnace. The following steps were performed.

First, the temperature is raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make a semi-molten state, and then raised and lowered by 5 ° C. so that the upper part of the precursor 2 is on the low temperature side.
/ Cm to 1015 ° C with a temperature gradient of 10 ° C / mi
The temperature was lowered at n. Next, a precursor crystal of a melt having a composition of Sm _1.8 Ba _2.4 Cu _3.4 O _x containing no Ag and prepared in advance was prepared so that the growth direction was parallel to the c-axis.
And the temperature was lowered from 1015 ° C. to 1010 ° C. at a rate of 0.5 ° C./hr. After maintaining at this temperature for 60 hours, the temperature was lowered to 980 ° C. in 30 hours and maintained at this temperature for 10 hours. Thereafter, it is gradually cooled to 910 ° C. over 70 hours (cooling rate 1 ° C./h/temperature gradient 5 ° C./cm=
The growth rate was 2 mm / h), and then the temperature was gradually lowered to room temperature in 100 hours to perform crystallization.

The material crystallized in this way is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere 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. in 10 hours, and gradually cooled from 500 ° C. to 300 ° C. over 200 hours, and then from 300 ° C. to 200 ° C. Until 200 hours, and then cooled to room temperature in 10 hours.

The outer diameter and the thickness of the obtained material were about 66 mm in outer diameter and about 28 mm in thickness due to shrinkage. Observation of the cross section with EPMA to cutting the _{material, (Sm a Y 1-a} ) 1 + p Ba 2 + q (Cu 1-b
Ag _{b) 3} O _7-x phase in the order of 0.1 to 30 [mu] m (S
_mc Y _1-c ) _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d )
The O _5-y phase was finely dispersed. Where p, q,
r, s, and y were values of -0.2 to 0.2, respectively, and x was a value of -0.2 to 0.6. A and c are precursor 2
The value is 1.0 to 0.9 from the upper surface to about 6 mm downward, and from about 0.9 to 0.1 from the interface between precursor 1 and precursor 2 to about 2 mm from precursor 1 to precursor 1 side. The concentration gradually changed from 0.1 to 0 under the precursor 1 from there. B was a value of 0.021 to 0.045, and was about 0.03 on average. Also, d was 0.002, which is about the measurement limit. The vicinity of the center of this material was photographed at a magnification of 1000 times using a polarizing microscope, and 70 × 9
Image analysis of the range of 0 μm showed that (Sm _c Y
_1-c ) _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ) O
The average particle size of the _5-y phase was 1.2 μm. Further, Ag of about 0.1 to 100 μm was finely dispersed throughout the entire sample. The vicinity of the center of this material was photographed at a magnification of 100 using a polarizing microscope, and image analysis was performed on an area of 700 × 900 μm. The average particle diameter of Ag was 26 μm. Further, there is no the Ag particle _{(Sm a Y 1-a)
1 + p Ba 2 + q (} Cu 1-b Ag b) 3 O 7-x phase near the XPS (X-ray Photoelectron Spectroscopy) pursuant measured in the vicinity of 3d peak of Ag, as shown in FIG. 7, the metal Ag and AgO, Satellite peaks not observed in Ag ₂ O and the like were observed. This is a peak change due to partial substitution of Ag at the Cu site. As a comparison, the measurement results of Ag metal, AgO, and Ag ₂ O are shown in FIGS. 8, 9, and 10, respectively. In addition, the entire material is oriented so that the axial direction of the disc-shaped material is the c-axis reflecting the seed crystal, the misorientation of the orientation between adjacent crystals is 1 ° or less, and there is substantially no small-angle grain boundary. Thus, a single-crystal superconducting material was obtained.

Next, the material was sliced at a distance of 1 mm from the interface between the precursor 1 and the precursor 2 of the material toward the precursor 1 to cut off the upper part of the precursor 2. A diameter of 39.2 mm, an inside diameter of 1
A Nd-Fe-B-based magnet (surface maximum magnetic flux density: 0.53 T (tesla)) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was moved 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disc-shaped superconductor almost coincided.
It was set apart. Superconductor is immersed in liquid nitrogen and temperature is 7
After cooling to 7K, the magnet was moved along the axial direction at a speed of 5 mm /
Min brought close to the superconductor. When the magnet was approached until the distance between the superconductor and the magnet was 0.1 mm, the repulsive force generated at this time was measured. When the distance between the superconductor and the magnet was 0.1 mm, a magnetic repulsion of 22 kg · f was observed. Power was gained.

Next, 2.5 × 2.
A sample of 5 × 2 mm was cut out, and the magnetic susceptibility was measured with a vibrating sample magnetometer. From the obtained susceptibility curve, Bean
When the critical current density (Jc) at a temperature of 77 K and an external magnetic field of 1 T was estimated by applying the model, 2 × 10 ⁴ A
/ Cm ² .

Further, a sample of 15.times.2.times.3 mm from the vicinity of the center of the disc-shaped material was placed in the thickness direction (2 mm direction).
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical current (Tc) was measured by a four-terminal method by applying a current in the length direction (direction of 15 mm). (Usually about 90K for Y-system).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and then the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage and moving it along the superconductor surface at a distance of about 1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 11, a maximum trapped magnetic flux density of 1.47T was obtained. The average magnetic flux density in the vertical direction of the disk material was 0.49 T, and the total magnetic flux (average magnetic flux density × area) was 17 Wb.

The mechanical strength when a force was applied parallel to the c-axis of the crystal was evaluated by a three-point bending test. Total length 20
mm sample, the measured length L = 14.2 mm,
When the width W is 3.5 mm, the thickness t is 1 mm, and the maximum load is P, the bending strength σ can be obtained from σ = 3PL / (2Wt ² ). Here, the speed of the crosshead is 0.5 m
m / min. The mechanical strength of this sample was 95 MPa.

As described above, in this embodiment, since the material in which 10 wt% of Ag is added to the Sm-based material having a high growth rate is laminated, the crystal growth time in the radial direction can be shortened, and (S
_{m c Y 1-c) 2} + r Ba 1 + s (Cu 1-d Ag d) O
A large-sized oxide superconductor having high mechanical strength and high magnetic properties at low cost can be manufactured by preventing the _5-y phase and Ag from agglomerating and coarsening.

Example 2 In this example, when a material (growth rate of about 1.10) in which 20 wt% of Ag was added to an Nd-based material having a high critical current density characteristic but a high growth rate, the growth rate was increased. Is an example in which a material (growth rate: 0.45) obtained by adding 10 wt% of Ag to an Sm-based material having an appropriate speed is stacked on the upper portion to grow a crystal.

First, RE ₂ O ₃ (Nd ₂ O in this embodiment)
₃ and Sm ₂ O ₃ ), BaCO ₃ , and CuO were weighed so that RE: Ba: Cu = 1.8: 2.4: 3.4, and then only BaCO ₃ and CuO were treated at 880 ° C. For 30 hours to obtain a calcined powder of BaCuO ₂ and CuO (BaCuO ₂ : CuO = 2.4: 1.0 in molar ratio). Next, Nd ₂ O ₃ weighed in advance, 0.5 wt% of Pt powder, and 20 wt% of Ag powder (average particle size: 0.35 μm) were mixed with the calcined powder, and the mixture was heated to 900 ° C. in the atmosphere. At 10
Fired for hours. Similarly, the previously calcined powder of BaCuO ₂ and CuO was added to the previously weighed Sm ₂ O ₃ and 0.5 wt.
% Pt powder and 10 wt% Ag powder were mixed and fired at 900 ° C. in the air for 10 hours. The obtained calcined powder was pulverized with a raikai machine to obtain an average particle size of about 2 μm. Further, when the obtained calcined powder was analyzed by powder X-ray diffraction, RE _{1 + p} Ba _{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-y} phase and _{Nd 4+ r Ba 2 + s (} Cu
_{A 1-d} Ag _d ) ₂ O _10-y phase was confirmed.

Of the synthetic powders thus produced,
For those with RE of Nd, outer diameter 80 mm, thickness 25 m
m to form a precursor 1
When E was Sm, the precursor 2 was prepared by press-forming into a disk shape having an outer diameter of 80 mm and a thickness of 4 mm.

Next, as shown in FIG. 6, the precursor 2 was laminated on the precursor 1, placed on an alumina substrate on which Nd ₂ O ₃ powder was spread, and placed in a two-zone furnace. . Next, the gas inside the furnace body was evacuated from the gas exhaust port, and the furnace was evacuated to 0.1 Torr.
And the atmospheric pressure by pouring ₂ 1% and Ar99% of the mixed gas. Thereafter, the following steps were performed while flowing the mixed gas at a flow rate of 0.2 L / min.

First, the temperature was raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make a semi-molten state, and then moved up and down 5 ° C. so that the upper part of the precursor 2 was on the low temperature side.
/ Cm up to 960 ° C with a temperature gradient of 10 ° C / min
To lower the temperature. Next, a seed crystal of a melt having a composition of Sm _1.8 Ba _2.4 Cu _3.4 O _x containing no Ag prepared in advance is placed on the top of the precursor 2 so that the growth direction is parallel to the c-axis. And the temperature was lowered from 960 ° C. to 955 ° C. at a rate of 0.5 ° C./hr. After maintaining at this temperature for 60 hours, the mixture was gradually cooled to 885 ° C. for 70 hours, and then gradually cooled to room temperature over 100 hours for crystallization.

The material crystallized in this way is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere where the oxygen partial pressure was 95% or more. Thereafter, the temperature was raised from room temperature to 700 ° C. for 10 hours while flowing oxygen gas into the furnace at a flow rate of 0.5 L / min. Hold at this temperature for 80 hours,
Cool down to 0 ° C in 100 hours, then 500 ° C to 300 ° C
Cool slowly in 200 hours until 300 ° C to 200 ° C
The mixture was gradually cooled in 00 hours, and then cooled to room temperature in 10 hours.

The outer diameter and thickness of the obtained material are
Only about 64mm in outer diameter and about 24mm in thickness
Was. This material was cut and the cross section was observed with EPMA.
(Nd_aSm_1-a)_{1 + p}Ba_{2 + q}(Cu
_1-bAg_b)₃O_7-xAbout 0.1 to 30 μm in phase
(Nd_cSm_1-c)_{4 + r}Ba_{2 + s}(Cu_1-d
Ag_d)₂O_10-yThe phases were finely dispersed. here
Where p, q, r, s, and y are values of -0.2 to 0.2, respectively.
And x was a value of -0.2 to 0.6. Also, a,
c is 1.0 to 1.0 mm from the upper surface of the precursor 2 to about 3 mm below.
0.9, from which the interface between precursor 1 and precursor 2
From 0.9 to 0.1 on the precursor 1 side up to 2 mm
The concentration gradually changes, and from there to under the precursor 1, the concentration is 0.1.
The value was 1 to 0. Also, b is 0.024 to 0.05.
It was about 0.035 on average. Also,
d was 0.0024, which is about the measurement limit. Of this material
Photographed near the center with a polarizing microscope at 1000x magnification
Then, when the image analysis of the area of 70 × 90 μm was performed,
(Nd_cSm_1-c)_{4 + r}Ba_{2 + s}(Cu_1-dA
g_d) ₂O_10-yThe average particle size of the phase was 3.2 μm.
Was. Further, about 0.1 to 100 μm over the entire sample
Of Ag was finely dispersed. Near the center of this material
Photographed at 100 × magnification using a polarizing microscope, 700 × 9
Image analysis of the range of 00 μm showed the average particle size of Ag.
Was 24 μm. Also, the disk reflecting the seed crystal
The entire material is oriented such that the axial direction of the shaped material is the c-axis,
The misorientation of the orientation between adjacent crystals is 1 ° or less, and the inclination is small.
A substantially single crystal superconducting material without grain boundaries was obtained.

Next, a slice was formed at a distance of 1 mm from the interface between the precursor 1 and the precursor 2 of the material toward the precursor 1 to cut off the upper part of the precursor 2. A diameter of 39.2 mm, an inside diameter of 1
An Nd-Fe-B-based magnet (maximum surface magnetic flux density: 0.53 T) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After the superconductor was immersed in liquid nitrogen and cooled to a temperature of 77K, the magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. The distance between the superconductor and the magnet is 0.1 mm
When the repulsive force generated at this time was measured by bringing the magnet close to the above, when the distance between the superconductor and the magnet was 0.1 mm, a magnetic repulsive force of 21 kg · f was obtained.

Next, a sample of 2.5 × 2.5 × 2 mm was cut out from the cut disk-shaped material, and the magnetic susceptibility was measured with a vibrating sample magnetometer. Applying a Bean model from the obtained magnetic susceptibility curve, the temperature is 77K, the external magnetic field is 1T.
The critical current density (Jc) at
× 10 ⁴ A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical temperature (Tc) was measured by a four-terminal method by passing a current in the length direction (direction of 15 mm). (Usually about 94K for Nd system).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage, moving the Hall element along the superconductor surface at a distance of about 0.1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 12, a maximum trapped magnetic flux density of 1.6 T was obtained. Also,
The average magnetic flux density in the vertical direction of the disk material is 0.47T,
The total magnetic flux (average magnetic flux density x area) was 15 Wb.

The mechanical strength when a force was applied in parallel to the c-axis of the crystal was evaluated by a three-point bending test. Total length 20
mm sample, the measured length L = 14.2 mm,
When the width W is 3.5 mm, the thickness t is 1 mm, and the maximum load is P, the bending strength σ can be obtained from σ = 3PL / (2Wt ² ). Here, the speed of the crosshead is 0.5 m
m / min. The mechanical strength of this sample was 75 MPa.

As described above, in this embodiment, since the material obtained by adding 10 wt% of Ag to the Sm-based material having a moderate growth rate is laminated, the crystal orientation can be controlled and the magnetic material has high magnetic properties. A large oxide superconductor can be manufactured.

[Embodiment 3] In this embodiment, the growth rate of G
When manufacturing a material in which 20 wt% of Ag is added to a d (50%) Y (50%)-based material (growth rate about 0.085), a material in which 20 wt% of Ag is added to a Gd-based material having a fast growth rate (growth rate) 0.
This is an example in which crystal growth is performed by laminating 12) on top.

First, RE₂O₃(In this embodiment, Gd (5
0%) Y (50%) and Gd), BaCO ₃, CuO source
The raw material powder becomes RE: Ba: Cu = 1.8: 2.4: 3.4.
After weighing, BaCO₃And CuO only 880
Baking at 30 ° C. for 30 hours.₂And CuO calcined powder
(A molar ratio of BaCuO₂: CuO = 2.4: 1.
0). Next, the calcined powder was added to the previously weighed RE₂
O₃And 0.5 wt% of Pt powder, and further Ag
Ag so that the element amount becomes 20 wt%₂O powder (average grain
(1.8 μm in diameter) and mixed in air at 900 ° C for 10 hours
Fired. The obtained calcined powder is crushed by a raikai machine.
The average particle diameter was set to about 2 μm. In addition, the obtained calcined powder
Analysis by powder X-ray diffraction showed that RE_{1 + p}Ba
_{2 + q}(Cu_{1 -B}Ag_b)₃O_7-xPhase and RE
_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O _5-ySure
It has been certified.

Of the synthetic powder thus produced,
Outer diameter of 8 for RE with Gd (50%) and Y (50%)
The precursor 1 was prepared by press-molding into a disk shape having a thickness of 0 mm and a thickness of 25 mm.
The precursor 2 was prepared by press-forming into a disk having a thickness of 4 mm and a thickness of 4 mm.

Next, as shown in FIG. 6, the precursor 2 is laminated on the precursor 1, placed on an alumina substrate on which Y ₂ O ₃ powder is spread, and placed in a two-zone furnace. The following steps were performed.

First, the temperature was raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make a semi-molten state, and then moved up and down 5 ° C. so that the upper part of the precursor 2 was on the low temperature side.
/ Cm to 1015 ° C with a temperature gradient of 10 ° C / mi
The temperature was lowered at n. Next, a precursor of a melt prepared in advance and having a composition of Gd _1.8 Ba _2.4 Cu _3.4 O _x containing no Ag was prepared so that the growth direction was parallel to the c-axis.
And the temperature was lowered from 1015 ° C. to 1010 ° C. at a rate of 0.5 ° C./hr. After maintaining at this temperature for 60 hours, the temperature was lowered to 990 ° C. in 20 hours, and maintained at this temperature for 10 hours. Thereafter, the mixture was gradually cooled to 920 ° C. over 70 hours, and then gradually cooled to room temperature for 100 hours to perform crystallization.

The material crystallized in this manner is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere 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. in 10 hours, and gradually cooled from 500 ° C. to 300 ° C. over 200 hours, and then from 300 ° C. to 200 ° C. Until 200 hours, and then cooled to room temperature in 10 hours.

The outer diameter and thickness of the obtained material are
Only about 66mm in outside diameter and about 24mm in thickness
Was. This material was cut and the cross section was observed with EPMA.
(Gd_a(Y_0.5Gd_0.5)_1-a)_{1 + p}Ba
_{2 + q}(Cu_1-bAg_b) ₃O_7-x0.1 ~
(Gd of about 30 μm_c(Y_0.5Gd_0.5)_1-c)
_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O_5-yPhase is fine
It was finely dispersed. Where p, q, r, s, y are
X is -0.2 to 0.6, respectively.
Value. A and c are 3 from the upper surface of the precursor 2 to the lower side.
The value is 1.0 to 0.9 up to about mm,
From the interface between body 1 and precursor 2 to about 2 mm toward precursor 1
The concentration gradually changes from 0.9 to about 0.1,
The values from 0.1 to 0 under the precursor 1 were 0.1 to 0. Also,
b is a value of 0.005 to 0.025, and on average is 0.005.
It was about 015. D is about the measurement limit of 0.0.
02. Near the center of this material using a polarizing microscope
Image at a magnification of 1000 × to cover an area of 70 × 90 μm.
When the image was analyzed, this (Gd_c(Y_0.5Gd_{0. 5})
_1-c)_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O
_5-yThe average particle size of the phase was about 0.9 μm. further,
Ag of about 0.1 to 100 μm is fine over the entire sample.
It was finely dispersed. Near the center of this material, use a polarizing microscope
And photographed at a magnification of 100 × with a size of 700 × 900 μm.
Image analysis of the box shows that the average particle size of Ag is 20 μm.
there were. Also, the direction of the axis of the disc-shaped material reflects the seed crystal.
The whole material is oriented so that the direction is the c-axis, and adjacent crystals
Azimuth deviation of 1 ° or less and no small tilt boundaries
A qualitatively single-crystal superconducting material was obtained.

Next, this material was sliced at a distance of 1 mm from the interface between the precursor 1 and the precursor 2 toward the precursor 1 to cut the upper part of the precursor 2. A diameter of 39.2 mm, an inside diameter of 1
An Nd-Fe-B-based magnet (surface maximum magnetic flux density: 0.53 T) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After the superconductor was immersed in liquid nitrogen and cooled to a temperature of 77K, the magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. The distance between the superconductor and the magnet is 0.1m
m and the repulsive force generated at this time was measured, and the distance between the superconductor and the magnet was 0.1 mm.
At this time, a magnetic repulsion of 20 kg · f was obtained.

Next, 2.5 × 2.
A sample of 5 × 2 mm was cut out, and the magnetic susceptibility was measured with a vibrating sample magnetometer. From the obtained susceptibility curve, Bean
When the critical current density (Jc) at a temperature of 77 K and an external magnetic field of 1 T was estimated by applying the model, 2.6 × 10
^{It was 4} A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical temperature (Tc) was measured by a four-terminal method by flowing a current in the length direction (direction of 15 mm). (In the case of a Gd system produced in the normal atmosphere, 91.
About 5K).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage and moving it along the superconductor surface at a distance of about 1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 13, a maximum trapped magnetic flux density of 1.52T was obtained. The average magnetic flux density in the vertical direction of the disk material was 0.5 T, and the total magnetic flux (average magnetic flux density × area) was 17 Wb.

The mechanical strength when a force was applied in parallel to the c-axis of the crystal was evaluated by a three-point bending test. Total length 20
mm sample, the measured length L = 14.2 mm,
When the width W is 3.5 mm, the thickness t is 1 mm, and the maximum load is P, the bending strength σ can be obtained from σ = 3PL / (2Wt ² ). Here, the speed of the crosshead is 0.5 m
m / min. The mechanical strength of this sample was 85 MPa.

As described above, in this embodiment, the growth rate is appropriate.
Material containing 10 wt% of Ag added to a natural Gd-based material
Therefore, the crystal growth time in the radial direction can be reduced,
(Gd _c(Y_0.5Gd_0.5)_1-c)_{2 + r}Ba
_{1 + s}(Cu_1-dAg_d) O_{5- y}Aggregation of phase and Ag
Prevents large size, low cost, high mechanical strength and high magnetic properties
Can produce large oxide superconductors with
You.

Example 4 The average particle size of Ag powder was 10 μm.
m, and the temperature gradient was set to 10 ° C./cm (growth rate: 1 mm / h).

The outer diameter and thickness of the obtained material were about 66 mm in outer diameter and about 28 mm in thickness due to shrinkage. Observation of the cross section with EPMA to cutting the _{material, (Sm a Y 1-a} ) 1 + p Ba 2 + q (Cu 1-b
Ag _{b) 3} O _7-x phase in the order of 0.1 to 30 [mu] m (S
_mc Y _1-c ) _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d )
The O _5-y phase was finely dispersed. Where p, q,
r, s, and y were values of -0.2 to 0.2, respectively, and x was a value of -0.2 to 0.6. A and c are precursor 2
The value is 1.0 to 0.9 from the upper surface to about 3 mm downward, and from about 0.9 to 0.1 from the interface between the precursor 1 and the precursor 2 to about 2 mm from the interface between the precursor 1 and the precursor 2. The concentration gradually changed from 0.1 to 0 under the precursor 1 from there. Further, b was a value of 0.0 to 0.009, and was about 0.003 on average. Also, d was 0.002, which is about the measurement limit. An image of the vicinity of the center of this material was taken at a magnification of 1000 using a polarizing microscope, and 70 × 90 μm
The image analysis of the range of m
_{c Y 1-c) 2 +} r Ba 1 + s (Cu 1-d Ag d) O
The average particle size of the _5-y phase was 1.5 μm. Further, Ag of about 0.1 to 100 μm was finely dispersed throughout the entire sample. The vicinity of the center of this material was photographed at a magnification of 100 using a polarizing microscope, and image analysis was performed on an area of 700 × 900 μm. The average particle diameter of Ag was 31 μm. In addition, the entire material was oriented so that the axial direction of the disc-shaped material was the c-axis, reflecting the seed crystal, but there was no small-angle grain boundary in which the misalignment between adjacent crystals was 1 ° or less. The size of the crystal grains was about 5 to 10 mm, and a superconducting material was obtained in which crystal grains having no small-angle grain boundaries were connected with a small angle of about 1 to 5 ° and oriented.

Next, a slice was formed at a distance of 1 mm from the interface between the precursor 1 and the precursor 2 of the material toward the precursor 1 to cut the upper part of the precursor 2. A diameter of 39.2 mm, an inside diameter of 1
An Nd-Fe-B-based magnet (surface maximum magnetic flux density: 0.53 T) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After the superconductor was immersed in liquid nitrogen and cooled to a temperature of 77K, the magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. The distance between the superconductor and the magnet is 0.1m
m and the repulsive force generated at this time was measured, and the distance between the superconductor and the magnet was 0.1 mm.
At this time, a magnetic repulsion of 20 kg · f was obtained.

Next, 2.5 × 2.
A sample of 5 × 2 mm was cut out, and the magnetic susceptibility was measured with a vibrating sample magnetometer. From the obtained susceptibility curve, Bean
When the critical current density (Jc) at a temperature of 77 K and an external magnetic field of 1 T was estimated by applying the model, 1.8 × 10
^{It was 4} A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical temperature (Tc) was measured by a four-terminal method by applying a current in a length direction (direction of 15 mm).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and then the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage and moving it along the superconductor surface at a distance of about 1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 14, a maximum trapped magnetic flux density of 1.34 T was obtained. The average magnetic flux density in the vertical direction of the disk material was 0.48 T, and the total magnetic flux (average magnetic flux density × area) was 16.5 Wb.

The mechanical strength when a force was applied in parallel to the c-axis of the crystal was evaluated by a three-point bending test. Total length 20
mm sample, the measured length L = 14.2 mm,
When the width W is 3.5 mm, the thickness t is 1 mm, and the maximum load is P, the bending strength σ can be obtained from σ = 3PL / (2Wt ² ). Here, the speed of the crosshead is 0.5 m
m / min. The mechanical strength of this sample was 81 MPa.

As described above, in the present embodiment, the critical temperature (Tc) and the critical current density (J
c) and Sm whose mechanical strength is slightly reduced, but whose growth rate is fast
Since a material in which 10 wt% of Ag is added to the system is laminated, the crystal growth time in the radial direction can be reduced, and (Sm
_{c Y 1-c) 2 +} r Ba 1 + s (Cu 1-d Ag d) O
A large-sized oxide superconductor having high mechanical strength and high magnetic properties at low cost can be manufactured by preventing the _{5- y} phase and Ag from agglomerating and coarsening.

Comparative Example 1 This comparative example is an example of manufacturing a YBaCuO-based superconductor to which 20 wt% of Ag having an outer diameter of about 66 mm is added.

First, Y₂O₃, BaCO₃, CuO
The raw material powder was changed to Y: Ba: Cu = 1.8: 2.4: 3.4.
After weighing, BaCO₃And CuO only 880
Baking at 30 ° C. for 30 hours.₂And CuO calcined powder
(A molar ratio of BaCuO ₂: CuO = 2.4: 1.
0). Next, the calcined powder was added to Y₂O
₃, 0.5 wt% Pt powder, 20 wt% Ag powder
(Average particle size 0.45μm) mixed in air at 900 ° C
It was baked for 10 hours. The obtained calcined powder is crushed with a raikai machine
The average particle diameter was set to about 2 μm. In addition, the obtained calcined powder
Analysis by powder X-ray diffraction showed that Y_{1 + p}Ba
_{2 + q}(Cu_1-bAg_b)₃O_7-xPhase and Y
_{2 + r}Ba_{1 + s}(Cu_1-dAg_d) O_5-ySure
It has been certified.

The synthetic powder produced in this way is
A precursor was prepared by press-forming into a disk having a thickness of 0 mm and a thickness of 25 mm.

This precursor was placed on an alumina substrate on which Y ₂ O ₃ powder was spread, and was placed in a two-zone furnace, and the following steps were performed.

First, the temperature was raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make a semi-molten state, and then moved up and down 5 ° C./c so that the upper part of the precursor was on the low temperature side.
m, and the temperature was lowered to 1005 ° C. at a rate of 10 ° C./min. Next, Y _1.8 Ba that has been prepared in advance
A seed crystal of a melt having a composition of _2.4 Cu _3.4 O _x is brought into contact with the top of the precursor so that the growth direction is parallel to the c-axis, and
The temperature was lowered from 05 ° C to 1000 ° C at a rate of 0.5 ° C / hr. After maintaining at this temperature for 200 hours, the solution was gradually cooled to 930 ° C. over 70 hours, and then gradually cooled to room temperature for 100 hours to perform crystallization.

The material crystallized in this manner is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere 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. in 10 hours, and gradually cooled from 500 ° C. to 300 ° C. over 200 hours, and then from 300 ° C. to 200 ° C. Until 200 hours, and then cooled to room temperature in 10 hours.

The obtained material had an outer diameter of about 66 mm and a thickness of about 24 mm due to shrinkage due to shrinkage. When this material was cut and the cross section was observed by EPMA, Y _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃ O
Y _{2 + r} Ba of about 0.1 to 30 μm in the _7-x phase
_{The 1 + s} CuO _5-y phase was finely dispersed. here,
p, q, and y were values of -0.2 to 0.2, respectively, and x was a value of -0.2 to 0.6. Also, b is 0.02-0.0.
043, which was about 0.028 on average. Also, d was 0.002, which is about the measurement limit. Near the center of the material taken at 1000 × magnification using a polarization microscope, the range of 70 × 90 [mu] m was image analysis, the retention time at the time of crystal growth because it took 100 hours and a long time, the Y _{2 + R} Ba _{1 + s} Cu _d Ag _d-1
The average particle size of the O _5-y phase was about 3.2 μm, which was relatively large for a system using Y as the RE. Furthermore, Ag of about 0.1 to 100 μm
Was finely dispersed. However, the vicinity of the center of this material was photographed with a polarizing microscope at a magnification of 100 times,
Image analysis of the range of 0 × 900 μm revealed that the average particle size of Ag was as large as 60 μm for the same reason as described above. As for the crystal orientation, the entire material was oriented so that the axial direction of the disc-shaped material was the c-axis, reflecting the seed crystal, and the misorientation between adjacent crystals was 5 ° or less. The size of a crystal grain without a small tilt grain boundary having a misorientation of 1 ° or less is about 5 to 30 mm, and the crystal grains without a small tilt grain boundary are connected with a small tilt angle of about 1 to 5 ° to be oriented. Was. In addition, there is a trace that the crystal growth rate in the radial direction has changed from about 40 mm centering on the seed crystal.
It was found that the crystal was grown only up to about the extent, and the crystal grew rapidly from there.

Next, slice processing was performed at 1 mm from the seed crystal installation surface side, and a 39.2 mm diameter, 16 mm inner diameter, 49 mm thick Nd-Fe-B-based magnet ( With the maximum surface magnetic flux density (0.53 T) approached, the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After immersing the superconductor in liquid nitrogen and cooling to a temperature of 77K,
The magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. When the distance between the superconductor and the magnet was approached until the distance between the superconductor and the magnet was 0.1 mm, and the repulsive force generated at this time was measured, when the distance between the superconductor and the magnet was 0.1 mm,
The magnetic repulsion was slightly low at 18 kg · f.

Next, 2.5 × 2.
A sample of 5 × 2 mm was cut out, and the magnetic susceptibility was measured with a vibrating sample magnetometer. From the obtained susceptibility curve, Bean
When the critical current density (Jc) at a temperature of 77 K and an external magnetic field of 1 T was estimated by applying the model, 1.5 × 10
^{It was 4} A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical current (Tc) was measured by a four-terminal method by flowing a current in the length direction (direction of 15 mm). Since a fine Ag powder was used, a high value was shown.

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage and moving it along the superconductor surface at a distance of about 1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 15, the gradient of the magnetic flux density in the vicinity of the rapidly grown end became gentle, and only a trapped magnetic flux density of 1.0 T at the maximum was obtained. The average magnetic flux density in the vertical direction of the disk material was 0.30 T, and the total magnetic flux (average magnetic flux density × area) was 10 Wb.

The mechanical strength when a force was applied parallel to the c-axis of the crystal was evaluated by a three-point bending test. Total length 20
mm sample, the measured length L = 14.2 mm,
When the width W is 3.5 mm, the thickness t is 1 mm, and the maximum load is P, the bending strength σ can be obtained from σ = 3PL / (2Wt ² ). Here, the speed of the crosshead is 0.5 m
m / min. The mechanical strength of this sample is 55 MPa, and Ag or Y _{2 + r} Ba _{1 + s} Cu _d Ag _d-1 O
Low due to coarsening of the _5-y phase.

[Comparative Example 2] In this comparative example, the growth rate of N
This is an example of manufacturing a material in which 20 wt% of Ag is added to d-system.

First, each raw material powder of Nd ₂ O ₃ , BaCO ₃ , and CuO was mixed with Nd: Ba: Cu = 1.8: 2.4: 3.4.
After weighing, only BaCO ₃ and CuO were added to 8
By calcining at 80 ° C. for 30 hours, a calcined powder of BaCuO ₂ and CuO was obtained (BaCuO ₂ : CuO = 2.4 by molar ratio:
1.0). Next, the calcined powder was weighed in advance with N
d ₂ O ₃ , 0.5 wt% Pt powder and 20 wt% Ag
Mixed with powder (average particle size 10μm)
For 10 hours. The obtained calcined powder was pulverized with a raikai machine to an average particle size of about 2 μm. Further, when the obtained calcined powder was analyzed by powder X-ray diffraction, Nd _{1 + p} Ba
_{2 + q} (Cu _1-b Ag _b ) ₃ O _7-x phase and Nd
_{4 + r} Ba _{2 + s} (Cu _1-d Ag _d ) ₂ O _10-y phase was confirmed.

The synthetic powder produced in this manner was used to prepare an outer diameter of 8
A precursor was prepared by press-forming into a disk having a thickness of 0 mm and a thickness of 25 mm.

Next, this precursor was placed on an alumina substrate on which Nd ₂ O ₃ powder was spread, and placed in a two-zone furnace. Next, the gas inside the furnace body was evacuated from the gas exhaust port, and the inside of the furnace was evacuated to 0.1 Torr. After that, a mixed gas of 1% O ₂ and 99% Ar was poured from the gas inlet to atmospheric pressure. Thereafter, the following steps were performed while flowing the mixed gas at a flow rate of 0.2 L / min.

First, the temperature is raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make it a semi-molten state, and then moved up and down so that the upper part of the precursor 2 is on the low temperature side.
10 ° C / mi to 968 ° C by adding a temperature gradient of 10 ° C / cm
The temperature was lowered at n. Next, a seed crystal of a Nd _1.8 Ba _2.4 Cu _3.4 O _x composition containing no Ag previously prepared is placed on top of the precursor so that the growth direction is parallel to the c-axis. The temperature was lowered from 968 ° C to 963 ° C at a rate of 0.5 ° C / hr. After maintaining at this temperature for 60 hours, it is gradually cooled to 893 ° C. in 70 hours (cooling rate 1 ° C./h)
/ Temperature gradient 10 ° C./cm=growth rate 1 mm / h), and then slowly cooled to room temperature over 100 hours to perform crystallization.

The material crystallized in this way is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere 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 700 ° C. in 10 hours, and maintained at this temperature for 80 hours.
The temperature was lowered to 100 ° C. in 100 hours, gradually cooled from 500 ° C. to 300 ° C. over 200 hours, gradually cooled from 300 ° C. to 200 ° C. in 200 hours, and then lowered to room temperature in 10 hours.

The outer diameter and thickness of the obtained material are
Only about 66mm in outside diameter and about 24mm in thickness
Was. This material was cut and the cross section was observed with EPMA.
Nd_{1 + p}Ba_{2 + q}(Cu_1-bAg_b)₃O
_7-xNd of about 0.1 to 30 μm in the phase_{4 + r}Ba
_{2 + s}(Cu_1-dAg_d)₂O_10-yFine phase
Was scattered. Here, p, q, r, s, and y are each-
Is a value between 0.2 and 0.2, and x is a value between -0.2 and 0.6.
Was. B is a value of 0 to 0.007, and on average,
Was about 0.003. D is about the measurement limit.
0.002. Polarized light microscope near the center of this material
The image was taken at a magnification of 1000 × using a 70 × 90 μm
When the image analysis of the box_{4 + r}Ba
_{2 + s}(Cu_1-dAg _d)₂O_10-yAverage particle size of phase
Was about 4 μm. In addition, 0.
Ag of about 1 to 100 μm was finely dispersed. this
Photographed near the center of the material at 100x magnification using a polarizing microscope
The area of 700 × 900μm was image-analyzed.
The average particle size of the Ag was 28 μm. But,
Is the grown crystal a seed crystal because of the high crystal growth rate?
But it did not reflect the orientation of the seed crystal,
It was polycrystalline.

Next, slice processing was performed at a point 1 mm from the side where the seed crystal of this material was placed, and a 39.2 mm diameter and an inner diameter of 1 mm attached to the tip of the load cell on the cut surface side.
An Nd-Fe-B-based magnet (surface maximum magnetic flux density: 0.53 T) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After the superconductor was immersed in liquid nitrogen and cooled to a temperature of 77K, the magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. The distance between the superconductor and the magnet is 0.1m
m and the repulsive force generated at this time was measured, and the distance between the superconductor and the magnet was 0.1 mm.
At that time, the magnetic repulsion was as low as about 15 kg · f.

Next, a sample of 2.5 × 2.5 × 2 mm was cut out from the cut disk-shaped material, and the magnetic susceptibility was measured using a vibrating sample magnetometer. Applying a Bean model from the obtained magnetic susceptibility curve, the temperature is 77K, the external magnetic field is 1T.
When the critical current density (Jc) at was estimated,
The value was as low as 1.5 × 10 ⁴ A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical temperature (Tc) was measured by a four-terminal method by applying a current in a length direction (direction of 15 mm).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and then the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage, moving the Hall element along the superconductor surface at a distance of about 0.1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, as shown in FIG. 16, a maximum trapped magnetic flux density of 0.7 T was obtained. Also,
The average magnetic flux density in the vertical direction of the disc material was 0.19 T, and the total magnetic flux (average magnetic flux density × area) was 6 Wb.

A sample was cut out from the polycrystalline sample in an appropriate direction, and the mechanical strength was evaluated by a three-point bending test. Using a sample with a total length of 20 mm, the measurement length L
= 14.2 mm, width W = 3.5 mm, thickness t = 1 mm, and maximum load P, the bending strength σ is σ = 3PL / (2W
t ² ). Here, the speed of the crosshead was 0.5 mm / min. The mechanical strength of this sample was 25 MPa, which was low because it was polycrystalline.

[Comparative Example 3] In this comparative example, Y without Ag was added.
This is an example in which a crystal growth is performed by stacking an Ag-free Sm-based material (growth rate 0.7) on the top when manufacturing a system material (growth rate 0.1).

First, RE ₂ O ₃ (Y ₂ O ₃ in this comparative example)
And Sm ₂ O ₃ ), BaCO ₃ , and CuO as raw material powders.
E: After weighing Ba: Cu = 1.8: 2.4: 3.4, only BaCO ₃ and CuO were calcined at 880 ° C. for 30 hours to obtain a calcined powder of BaCuO ₂ and CuO. (Molar ratio: BaCuO ₂ : CuO = 2.4: 1.0). next,
To this calcined powder, pre-weighed RE ₂ O ₃ and 0.5 were added.
The mixture was mixed with Pt powder (average particle size: 0.01 μm) of wt% and fired at 900 ° C. in the air for 10 hours. The obtained calcined powder was pulverized with a raikai machine to an average particle size of about 2 μm. Further, when the obtained calcined powder was analyzed by powder X-ray diffraction, RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃ O
_7-x phase and RE _{2 + r} Ba _{1 + s} (Cu _1-d Ag
_d ) O5 _-y phase was observed.

[0096] Of the synthetic powder thus produced,
For those with RE of Y, outer diameter 80 mm, thickness 25 mm
The precursor 1 was prepared by press molding into a disk shape of
For Sm, precursor 2 was prepared by press-forming into a disk having an outer diameter of 80 mm and a thickness of 8 mm.

Next, as shown in FIG. 6, the precursor 2 was laminated on the upper part of the precursor 1, placed on an alumina substrate on which Y ₂ O ₃ powder was spread, and placed in a two-zone furnace. The following steps were performed.

First, the temperature was raised from room temperature to 1100 ° C. in 50 hours, kept at this temperature for 20 minutes to make a semi-molten state, and then moved up and down 5 ° C. so that the upper part of the precursor 2 was on the low temperature side.
/ Cm to 1065 ° C with a temperature gradient of 10 ° C / mi
The temperature was lowered at n. Next, Sm
_1.8 (Ba _0.75 Sr _0.25 ) _2.4 Cu _3.4 O _x
A seed crystal of a melt having a composition is brought into contact with the upper part of the precursor 2 so that the growth direction is parallel to the c-axis.
The temperature was lowered to 1060 ° C at a rate of ° C / hr. After maintaining at this temperature for 60 hours, the temperature was lowered to 1000 ° C. in 60 hours and maintained at this temperature for 10 hours. Then 930 ° C
Until 70 hours, and then slowly to room temperature for 100 hours for crystallization.

The material crystallized in this manner is placed in another gas-replaceable furnace, and is set to 0.1 by a rotary pump.
After evacuation of the furnace to Torr, oxygen gas was flowed into the furnace to create an atmospheric pressure atmosphere 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. in 10 hours, and gradually cooled from 500 ° C. to 300 ° C. over 200 hours, and then from 300 ° C. to 200 ° C. Until 200 hours, and then cooled to room temperature in 10 hours.

The outer diameter and thickness of the obtained material were about 68 mm in outer diameter and about 28 mm in thickness due to shrinkage. Observation of the cross section with EPMA to cutting the _{material, (Sm a Y 1-a} ) 1 + p Ba 2 + q Cu 3 O
_{In the 7-x} phase, about 0.1 to 30 μm (Sm
_{cY1 -c} ) _{2 +} rBa1 ₊ sCuO5 _-y phase was finely dispersed. Here, p, q, r, s, and y were values of -0.2 to 0.2, respectively, and x was a value of -0.2 to 0.6. Also, a and c are 3 mm downward from the upper surface of the precursor 2.
To the extent it is a value of 1.0-0.9, from which precursor 1
From the interface of the precursor 2 to the precursor 1 side, the concentration gradually changes from 0.9 to about 0.1 up to about 2 mm, and from there to below the precursor 1, the concentration is 0.1 to 0. Was. The vicinity of the center of this material was photographed at a magnification of 1000 using a polarizing microscope, and the area of 70 × 90 μm was image-analyzed. The average particle size of the (Sm _c Y _1-c ) _{2 + r} Ba _{1 + s} CuO _5-y phase Was 1.2 μm. However, because of the high crystal growth rate, the grown crystal grew radially from the seed crystal, but did not reflect the orientation of the seed crystal and was in a polycrystalline form.

Next, this material was sliced at a distance of 1 mm from the interface between the precursor 1 and the precursor 2 toward the precursor 2 to cut off the upper part of the precursor 2. A diameter of 39.2 mm, an inside diameter of 1
An Nd-Fe-B-based magnet (surface maximum magnetic flux density: 0.53 T) having a thickness of 6 mm and a thickness of 49 mm was approached, and the magnetic repulsion was measured by an autograph as follows. First, the magnet was installed at a distance of 300 mm from the superconductor so that the axial direction of the ring magnet and the axial direction of the disk-shaped superconductor almost coincided. After the superconductor was immersed in liquid nitrogen and cooled to a temperature of 77K, the magnet was approached to the superconductor at a speed of 5 mm / min along the axial direction. The distance between the superconductor and the magnet is 0.1m
m and the repulsive force generated at this time was measured, and the distance between the superconductor and the magnet was 0.1 mm.
At this time, a magnetic repulsion of 14 kg · f was obtained.

Next, 2.5 × 2.
A sample of 5 × 2 mm was cut out, and the magnetic susceptibility was measured with a vibrating sample magnetometer. From the obtained susceptibility curve, Bean
When the critical current density (Jc) at a temperature of 77 K and an external magnetic field of 1 T was estimated by applying the model, 1.3 × 10
^{It was 4} A / cm ² .

Further, a sample of 15 × 2 × 3 mm was placed in the thickness direction (2 mm direction) from the vicinity of the center of the disc-shaped material.
Was cut out so as to be substantially parallel to the c-axis direction of the crystal, and a critical temperature (Tc) was measured by a four-terminal method by applying a current in a length direction (direction of 15 mm).

Next, the superconductor was cooled from room temperature to a temperature of 77 K while applying an external magnetic field of 2T, and then the magnetic field was removed to measure the magnetic flux density captured in the superconductor. This measurement was performed by mounting the Hall element on an XY stage and moving it along the superconductor surface at a distance of about 1 mm from the superconductor surface, and measuring the axial magnetic flux density distribution of the disc-shaped material. As a result, a trapped magnetic flux density of 0.67 T at the maximum was obtained as shown in FIG. The average magnetic flux density in the vertical direction of the disk material was 0.25 T, and the total magnetic flux (average magnetic flux density × area) was 9 Wb.

A sample was cut out from a polycrystalline sample in an appropriate direction, and the mechanical strength was evaluated by a three-point bending test. Using a sample with a total length of 20 mm, the measurement length L
= 14.2 mm, width W = 3.5 mm, thickness t = 1 mm, and maximum load P, the bending strength σ is σ = 3PL / (2W
t ² ). Here, the speed of the crosshead was 0.5 mm / min. The mechanical strength of this sample was 28 MPa, which was low because it was polycrystalline.

In the above embodiments, BaCuO ₂ and CuO
RE ₂ O ₃ , Pt powder, and Ag powder weighed in advance are mixed with the calcined powder of _{No. 1} and calcined at 900 ° C. to obtain RE _{1 + p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃
O _7-x phase and RE _{2 + r} Ba _{1 + s} (Cu _1-d A
g _d ) Although the calcined powder is mainly composed of the O _5-y phase, BaCuO ₂ , CuO, RE
_Even if the same melt crystallization is performed by molding in the state of a mixed powder of ₂ O ₃ , Pt powder and Ag powder, 800
RE _{1 + p} Ba by solid phase reaction in the range of
_{2 + q} (Cu _1-b Ag _b ) ₃ O _7-x phase and RE
The same effect can be obtained because the light passes through the _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ) O _5-y phase.

[0107]

As described in detail above, according to the present invention,
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. In the method of producing a RE-Ba-Cu-O-based oxide superconductor by performing a slow cooling step and growing a crystal while adding, the growth rate is 0.1 to 0.1.
By stacking a material of a system having a range of 0.5 mm / h / ° C. on the upper portion and growing the crystal, RE-Ba-
A Cu-O-based oxide superconducting material can be manufactured in a short time with high yield.

As described above, according to the present invention,
By laminating an RE-based material having an appropriate growth rate on an RE-based material having a slow growth rate or an RE-based material having a too high growth rate and performing crystal growth, the crystal growth time in the radial direction can be controlled. _{2 + r} Ba _{1 + s} (Cu _1-d Ag _d ) O
_5-y phase or RE _{4 + r} Ba _{2 + s} (Cu _1-d Ag
_d) prevents 2 O _10-y phase and agglomeration coarsening of Ag, at low cost, high mechanical strength, can be produced a large oxide superconductor having high magnetic properties.

[Brief description of the drawings]

FIG. 1. Degree of supercooling and Y _{1 + p} Ba _{2 + q} Cu ₃ O _7-x
The figure which shows the relationship with the growth rate of a phase crystal.

FIG. 2 Degree of supercooling and Gd _{1 + p} Ba _{2 + q} Cu ₃ O
_The figure which shows the relationship with the growth rate of a _7-x phase crystal.

FIG. 3 shows the degree of supercooling and Sm _{1 + p} Ba _{2 + q} Cu ₃ O
_The figure which shows the relationship with the growth rate of a _7-x phase crystal.

FIG. 4 shows the degree of supercooling and Nd _{1 + p} Ba _{2 + q} Cu ₃ O
_The figure which shows the relationship with the growth rate of a _7-x phase crystal.

FIG. 5 is a diagram showing a growth rate when the amount of Ag added to each RE is changed.

FIG. 6 is a view showing a state in which a precursor 2 is laminated on a precursor 1;

FIG. 7 shows X of the oxide superconductor produced in Example 1.
The figure which shows a PS measurement result.

FIG. 8 is a view showing an XPS measurement result of metal Ag.

FIG. 9 is a view showing an XPS measurement result of AgO.

FIG. 10 is a graph showing an XPS measurement result of Ag ₂ O;

FIG. 11 is a diagram showing a trapped magnetic flux density of the oxide superconductor manufactured in Example 1.

FIG. 12 is a diagram showing a trapped magnetic flux density of the oxide superconductor manufactured in Example 2.

FIG. 13 is a diagram showing a trapped magnetic flux density of the oxide superconductor manufactured in Example 3.

FIG. 14 is a graph showing a trapped magnetic flux density of an oxide superconductor manufactured in Example 4.

FIG. 15 is a diagram showing a trapped magnetic flux density of the oxide superconductor manufactured in Comparative Example 1.

FIG. 16 is a diagram showing a trapped magnetic flux density of an oxide superconductor manufactured in Comparative Example 2.

FIG. 17 is a diagram showing a trapped magnetic flux density of an oxide superconductor manufactured in Comparative Example 3.

[Explanation of symbols]

 1,2 precursor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideyoshi Haseyama 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Shigeo Nagaya Kita-Sekiyama 20 No. 1 Chubu Electric Power Co., Inc. Power Technology Research Laboratory F term (reference) 4G047 JA02 JB02 JC02 JC03 KA01 KA18 KB01 KB04 KB17 KC06 LB03 4G077 BC53 CA05 CA09 EC02 EC07 5G321 AA01 AA04 BA03 BA05 BA11 CA04 CA05 DB02 DB17 DB44 DB47 DB47 DB48

Claims (17)

[Claims] 1. RE (RE is 1 containing Y)
Or two or more rare earth metal elements), Ba and Cu, and a growth rate of 0.1 mm / h / ° C. or less or 0.5 or less.
a first compact containing a first phase of not less than mm / h / ° C. and RE, Ba and Cu as constituent elements, and having a growth rate of more than 0.1 mm / h / ° C. and 0.5 mm / h / After laminating a second compact containing a second phase smaller than 0 ° C. and firing at a temperature not lower than the melting point of the first and second phases, a seed crystal is placed on the second compact side. A method for producing an oxide superconductor by crystallizing from the second molded body side to the first molded body side by slow cooling or temperature holding. 2. The method according to claim 1, wherein said first and second phases are RE _{1 + p} B
a _{2 + q} (Cu _{1− b} Ag _b ) ₃ O _7−x (−0.2 ≦
p ≦ 0.2, −0.2 ≦ q ≦ 0.2, 0 ≦ b ≦ 0.05, −
2. The method for producing an oxide superconductor according to claim 1, wherein 0.2 ≦ x ≦ 0.6) phase. 3. In the crystallization step, the oxide superconductor is made of RE _{1+ p} Ba _{2 + q} (Cu _1-b Ag _b ) ₃
O _7-x (−0.2 ≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2,
3. The method for producing an oxide superconductor according to claim 1, wherein crystallization is performed so as to include 0 ≦ b ≦ 0.05 and −0.2 ≦ x ≦ 0.6) phase. 4. 4. The method according to claim 1, wherein the first and second compacts are 5 wt%.
2. The composition of claim 1, wherein the composition contains about 60 wt% of Ag.
4. The method for producing an oxide superconductor according to any one of claims 1 to 3. 5. The method according to claim 5, wherein the Ag is 5 wt% to 6 wt.
The method for producing an oxide superconductor according to claim 4, wherein the compound is a 0 wt% Ag compound. 6. The method according to claim 1, wherein the Ag has an average particle size of 0.3 μm to 1.0 μm.
8 μm of a powder of Ag or an Ag compound, or a powder of Ag and an Ag compound having an average particle diameter of 0.3 μm to 1.8 μm, being dispersed in the first and second compacts. A method for producing an oxide superconductor according to claim 1. 7. The method according to claim 1, wherein the first and second molded bodies are Pt,
0.05 wt% to 5 wt% of at least one element selected from Pd, Ru, Rh, Ir, Os and Re
The method for producing an oxide superconductor according to any one of claims 1 to 6, wherein 8. The method according to claim 1, wherein the first and second molded bodies are 0.0
The method for producing an oxide superconductor according to any one of claims 1 to 6, comprising 5 wt% to 5 wt% of Pt. 9. The second compact is laminated on top of the first compact, and in the crystallization step, a temperature gradient is set up and down so that the upper portion of the second compact is at a lower temperature side. The method for producing an oxide superconductor according to any one of claims 1 to 8, wherein the temperature is additionally lowered. 10. The method according to claim 1, wherein the seed crystal does not contain Ag.
_1.8Ba_2.4Cu _3.4O_xComposition (RE is 1 containing Y
Seed crystal of melt of seed or two or more rare earth metal elements)
The method according to any one of claims 1 to 9, wherein
The method for producing an oxide superconductor according to the above. 11. RE _{1 + p} Ba _{2 + q} (Cu _1-b A
g _b ) ₃ O _7-x (RE is one or more rare earth metal elements including Y, -0.2 ≦ p ≦ 0.2, −0.2 ≦ q
≤0.2, 0.005≤b≤0.05, -0.2≤x≤0.2.
6) In an oxide superconductor containing a phase in which Ag is finely dispersed, the misalignment of the orientation between adjacent crystals is ± 5.
° or less, an oxide superconductor. 12. The RE_{1 + p}Ba_{2 + q}(Cu
_1-bAg_b)₃O_{7 -X}During the phase, RE_{2 + r}Ba
_{1 + s}(Cu_1-dAg_d) O_5-yPhase or RE
_{4 + r}Ba_{2 + s}(Cu_1-dAg_d)₂O_10-yphase
(-0.2 ≦ r ≦ 0.2, −0.2 ≦ s ≦ 0.2, 0 ≦ d ≦
0.05, -0.2 ≦ y ≦ 0.2) is finely dispersed
The oxide superconductivity according to claim 11, characterized in that:
body. 13. The oxide superconductor according to claim 11, wherein the Ag has an average particle size of 30 μm or less. 14. The RE _{2 + r} Ba _{1 + s} (Cu
The average particle size of the _1-d Ag _d ) O _{5- y} phase is 0.5 μm to 3 μm, and the RE _{4 + r} Ba _{2 + s} (Cu _1-d
Ag _d ) ₂ O _10-y phase has an average particle size of 1 μm to 5 μm
The oxide superconductor according to claim 12, wherein: 15. The method according to claim 15, wherein the misalignment between the adjacent crystals is ±
The angle is not more than 1 °.
The oxide superconductor according to any one of the above. 16. RE (RE is one or more rare earth metal elements including Y), Ba and Cu as constituent elements and a growth rate of 0.1 mm / h / ° C. or less or 0.1 mm / h / ° C. or less.
A first molded body containing a first phase of 5 mm / h / ° C. or more;
It contains RE, Ba and Cu as constituent elements and has a growth rate of more than 0.1 mm / h / ° C. and 0.5 mm / h / ° C.
A second compact comprising a smaller second phase. 17. The method according to claim 17, wherein said first and second phases are RE._{1 + p}
Ba_{2 + q}(Cu _1-bAg_b)₃O_7-x(-0.2
≦ p ≦ 0.2, −0.2 ≦ q ≦ 0.2, 0 ≦ b ≦ 0.05,
-0.2 ≦ x ≦ 0.6) phase
Item 17. The laminate according to Item 16.