JPH06162842A - Manufacture of bi oxide superconductor wire rod and raw material powder for manufacturing bi oxide superconductor wire rod - Google Patents

Abstract

PURPOSE:To quickly provide a Bi oxide superconductor wire rod including no impurity phase, by enclosing the raw material mixed power of the Bi oxide superconductor wire rod in a sheathing material to be plastic-worked and then heat-treated to have a specific superconductor phase. CONSTITUTION:Bi oxide superconductor wire material is manufactured by a sheathing method as follows: Powder, having chemical structure in a formula I, and raw material mixed powder, composed of Ca-Sr-Cu-O compound powder and also not including a (Ca, Sr)2PbO4 compound, are previously prepared so that (Bi, Pb):(Sr, Ba):C:Cu in this mixed powder can have a proportion nearly 2:2:2:3. Then the mixed powder is enclosed in a sheathing material to perform plastic working, and then is heat-treated in atmosphere or a non-oxidizing atmosphere to form mixed powder in the sheath material to a formula II type oxide superconductor, thus obtaining a target wire rod. In the formula I, 0.05<=x<=0.7, 0<=y<=0.2.

Description

Detailed Description of the Invention

[0001]

The present invention has a good critical current characteristic,
The present invention relates to a novel method for producing a Bi-based oxide superconducting wire which is optimal as a material for a superconducting magnet while applying a sheath method, and a raw material powder for producing such a wire.

[0002]

2. Description of the Related Art Since rare earth elements-alkaline earth elements-copper oxides have been attracting attention as superconductors, superconducting phenomena have been studied for many composite oxides. For example, a Bi-based oxide has a superconducting transition temperature (hereinafter, simply referred to as Tc
Is described as a substance having a high Tc such as 80K (low temperature phase) or 110K (high temperature phase).

Among the Bi-based oxides, the Bi-based oxide superconductors belonging to the category of Tc of about 110K have the excellent characteristics that Tc is sufficiently higher than the boiling temperature of liquid nitrogen and is not toxic. Especially, the application to superconducting wire is regarded as promising, and many researches and developments have been made so far. This high-temperature phase Bi-based oxide superconductor is (Bi + Pb), S
It contains r, Ca and Cu, and their atomic molar ratio is approximately 2:
The ratio of 2: 2: 3 is typical [for example, (Bi _1-x Pb _x ) ₂ Sr ₂ Ca ₂ Cu ₃ O _10- δ: where 0.05 ≦ x ≦ 0.7], It is also called a Bi-based 2223 type oxide superconductor. A high-temperature phase Bi-based oxide superconductor in which a part of Sr is replaced with Ba is also known.

When considering application of the Bi type 2223 type oxide superconductor to a superconducting magnet or the like, it is an essential requirement to make the oxide superconductor into a wire. The sheath method is the most general method for producing a Bi-based oxide superconductor wire, but when a Bi-based 2223 type oxide superconductor wire is produced by this sheath method, it is usually performed as follows. Be seen. First, the oxides and carbonates of the respective constituent elements are used as raw materials, which are mixed at a predetermined ratio, and then mixed in the atmosphere at 750 to 820.
After repeating the calcination at a temperature of about ° C, the calcination is performed for a short time at a temperature at which a Bi-based 2223 type oxide superconductor phase is generated. Then, after crushing the obtained sample, it is enclosed in a sheath material such as a silver pipe and subjected to wire drawing and rolling to form a sheath wire, and this wire is subjected to three heat treatments and a uniaxial press between the heat treatments. Give.

When the superconducting wire is put into practical use, particularly when it is used as a superconducting magnet after being coiled, the critical current value per unit area of the wire (sheath material + superconducting material), that is, the critical current density (overall criticality). Current density: hereinafter simply referred to as Jc) is required to be as large as possible. In order to improve the Jc value of the wire,
Either the Jc value of the oxide superconductor itself should be increased or the ratio of the sheath material in the wire should be decreased. However, there is a limit to reducing the ratio of the sheath material in the whole wire due to processing restrictions. is there. Therefore, the only way to improve the Jc value of the wire is to increase the Jc value of the oxide superconductor itself. For that purpose, the oxide in the wire should be made as single phase as possible and the crystals should be oriented. I need to do it. Because the impurity phase in the wire interferes with the flow of superconducting current,
The effective cross-sectional area of the superconducting portion is reduced, and the oxide superconductor has a characteristic that the current easily flows in the ab plane direction of the crystal, but the current hardly flows in the direction perpendicular to the crystal plane. Because it is.

In consideration of these points, conventionally, a wire rod is conventionally pressed at a pressure of about 7 ton / cm ² , and this is pressed in air at 830
It was common to repeat the step of heat treatment at ℃ 3 times. However, even if the heat treatment is carefully performed, a large impurity phase remains in many places in the superconductor, and the Jc value of the wire produced by the conventional method is 17,0.
It was about 00 A / cm ² (77K, 0T). Further, although the crystal orientation is improved by repeating the pressing three times, there is a defect that cracks generated during pressing remain after the heat treatment and hinder the improvement of Jc value.
Further, the production rate of the Bi-based 2223 type oxide superconductor phase (hereinafter sometimes referred to as Bi-2223 phase) in the sheath material is the production rate in the case of manufacturing as a bulk body (about 1
It was very slow as compared with the case of 00 hours), and there was a drawback that it took a very long time (about 200 hours) to heat the wire.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and an object thereof is to quickly obtain a Bi-based oxide superconductor wire containing no impurity phase. To provide a raw material powder for producing such an oxide superconductor.

[0008]

[Means for Solving the Problems] A book that has achieved the above object
Inventive method means (Bi_1-x Pb_x )₂ (Sr_1-y Ba
_y )₂ CaCu₂ O_Ten- δ (however, 0.05 ≦ x ≦ 0.
Powder having a chemical structure of 7,0 ≦ y ≦ 0.2), and Ca
-Sr-Cu-O-based compound powder, and (C
a, Sr)₂ PbO_Four Raw material mixed powder containing no compound
In the mixed powder (Bi, Pb): (Sr, Ba):
So that the ratio of Ca: Cu is close to 2: 2: 2: 3
Prepared in advance, and then enclose this mixed powder in the sheath material.
Plastic working, and then in air or in a non-oxidizing atmosphere.
The powder mixture in the sheath material is heat treated in air (Bi, P
b)₂ (Sr, Ba)₂ Ca₂ Cu₃ O-type oxide superconductivity
Bi-based oxide superconductor wire having the gist in the body phase
Is a manufacturing method. The raw material mixed powder used at this time
Is a Bi compound, Pb compound, Sr compound, Ba compound
And the Ca compound and the Cu compound are (Bi, Pb):
(Sr, Ba): Ca: Cu approximates 2: 2: 2: 3
After mixing in different proportions, 700 in a non-oxidizing atmosphere
Prepared by heat treatment at a temperature of ~ 830 ° C
The ones are the best.

In the above manufacturing method, the raw material mixed powder is mixed with
In the mixed powder (Ca, Sr)₂ PbO _Four Contains no compounds
In this way, the purpose is to adjust in advance,
(Bi_1-x Pb_x )₂ (Sr_1-y Ba_y )₂ CaCu₂ 
O_Ten- δ (however, 0.05 ≦ x ≦ 0.7, 0 ≦ y ≦ 0.
It has the chemical structure of 2) and (Ca, Sr)₂ PbO _Four 
Compound-free raw material powder and Ca-Sr-Cu-O system
Compound powders are prepared separately, and these (Bi, P
b) :( Sr, Ba): Ca: Cu becomes 2: 2: 2: 3
After mixing so that the ratio is similar, enclose in a sheath material.
Plastic working is performed, and then the wire rod is manufactured in the same manner as above.
You may choose to build it. Also used at this time (Bi_1-x 
Pb_x )₂ (Sr_1-y Ba_y )₂ CaCu₂ O_Ten- δ system
Raw material powders are Bi compound, Pb compound, Sr compound, B
The a compound, the Ca compound and the Cu compound are (Bi, P
b) :( Sr, Ba): Ca: Cu becomes 2: 2: 1: 2
Mix in similar proportions and then in a non-oxidizing atmosphere
Manufactured by heat treatment at a temperature of 700-830 ° C
What was done is the best.

Furthermore, an object of the present invention is to include B containing no Pb.
i₂ (Sr_1-y Ba_y)₂ CaCu₂O_Ten- δ (however, 0
≦ y ≦ 0.2) -based raw material powder and Ca-Pb-Sr-Cu
-O-based compound powders are prepared separately, and these (B
i, Pb) :( Sr, Ba): Ca: Cu is 2: 2:
After mixing in a ratio close to 2: 3, non-oxidizing
Heat treatment is performed in an atmosphere at a temperature of 700 to 830 ° C. (Bi
_1-x Pb_x)₂ (Sr_1-yBa_y )₂ CaCu₂ O_Ten- δ
(However, 0.05 ≦ x ≦ 0.7, y has the same meaning as before)
Raw material mixed powder in which a superconductor phase having a chemical structure is generated
After encapsulating this in a sheath material and performing plastic working,
Sheath material heat treated in air or non-oxidizing atmosphere
The raw material mixed powder in (Bi, Pb)₂ (Sr, Ba)₂ 
Ca₂ Cu ₃ O-type oxide superconductor phase
It is also achieved by using. In addition, in this manufacturing method
The mixed powder before heat treatment in a non-oxidizing atmosphere.
Enclose the powder in a sheath material and then 700 in a non-oxidizing atmosphere.
Heat-treated at a temperature of ~ 830 ° C and then in a sheath material (Bi_1-x 
Pb_x )₂ (Sr_1-y Ba_y )₂ CaCu₂ O_Ten- δ
(However, 0.05 ≦ x ≦ 0.7, y has the same meaning as before)
Raw material mixed powder in which a superconductor phase having a chemical structure is generated
After that, the sheath material is plastically worked and
Heat treatment in a medium or non-oxidizing atmosphere and mix in the sheath material.
Combined powder (Bi, Pb)₂ (Sr, Ba)₂ Ca₂ Cu
₃ It is also possible to have technical applications such as using an O-type oxide superconductor phase.
is there.

[0011]

The present inventors have confirmed that Bi-2223 in the sheath material is used.
In order to promote the generation of phases and reduce the amount of impurity phases, studies were repeated from various angles. And first, in the sheath material, Bi-2
It was considered that the reason why the formation rate of the 223 phase was slow was due to the (Ca, Sr) ₂ PbO ₄ compound contained in the raw material powder. That is, it is contained in the raw material powder (Ca, S
It was considered that the r) ₂ PbO ₄ compound decomposed during the heat treatment to generate oxygen gas, which caused the oxygen partial pressure in the sheath material to be higher than atmospheric pressure, thereby suppressing the formation of the Bi-2223 phase. . It was also considered that this (Ca, Sr) ₂ PbO ₄ compound becomes an impurity phase in the sheath material. Generation of such a compound cannot be suppressed by a conventional raw material powder prepared in an oxidizing atmosphere.

Therefore, the present inventors have found that (Ca, Sr)₂ P
bO_Four In order to produce a raw material powder containing no compound,
We proceeded with the examination. As a result, 700 to 8 in a non-oxidizing atmosphere
Raw material if heat-treated at a temperature of 30 ° C.
In powder (Ca, Sr)₂ PbO_Four No compound is produced
I found out Then, using such raw material powder,
If the oxide superconducting wire is manufactured by applying the
(Ca, Sr)₂ PbO _Four The conventional raw material powder containing
Compared to the case of using it, it takes a short time and with one press
Bi-2223 phase is almost single phase, and the impurity phase is extremely small.
We have found that we can produce high Jc wire without
It was

The main factors by which the present invention can solve the conventional problems will be described in more detail in comparison with the conventional method. In the case of a wire made using raw material powder that has been heat treated in the atmosphere,
When the wire is heat treated at around 840 ° C, (Ca, Sr) ₂ P
The decomposition reaction of the bO ₄ compound occurs, and oxygen gas is generated by the reaction from Pb ⁴⁺ to Pb ²⁺ . However, since the diffusion rate of oxygen in the sheath material is much slower than the production rate of oxygen generated by the chemical reaction, the generated oxygen is not instantaneously released from the inside of the sheath material to the atmosphere. Therefore, the oxygen partial pressure inside the sheath material is slightly higher than that in the atmosphere, and the generation of the Bi-2223 phase is suppressed. Therefore, Bi-2 in the sheath material
The production rate of the 223 phase depends on the diffusion rate of oxygen in silver, and in order for the Bi-2223 phase to be produced in the sheath material, a long heat treatment of about 200 hours is required, and the reactivity is high. Three uniaxial presses were required to improve the degree of orientation.

On the other hand, the (Ca, Sr) ₂ PbO ₄ compound is not formed in the raw material powder produced in the non-oxidizing atmosphere. Since this is heat treated in a non-oxidizing atmosphere, P
b is Bi-2212 phase in the form of _{^{Pb 2+ [(Bi 1-x}} Pb
_x ) ₂ (Sr _1-y Bay _y ) ₂ CaCu ₂ O _10- δ phase] is considered to be a solid solution. For this reason, the oxygen gas is not generated by the reaction of Pb ⁴⁺ to Pb ²⁺ generated in the above conventional method, and an oxidizing atmosphere is not created in the sheath material. Therefore, the oxygen partial pressure in the sheath material does not increase and Bi-
The formation of the 2223 phase was not suppressed, and Bi-222 was formed in the sheath material by one pressing and two heat treatments for about 100 hours in total.
Three phases can be produced. In addition, (Ca, Sr) ₂
Since it does not contain PbO ₄ etc., the impurity phase remaining after the final heat treatment becomes small. Furthermore, the heat treatment for a short time causes Bi-22
Since 23 phases are generated, the number of presses can be reduced,
Destruction of Bi-2223 phase by pressing is eliminated.

As described above, the raw material powder used in the present invention contains the Bi compound, the Pb compound, the Sr compound, the Ba compound, the Ca compound and the Cu compound (Bi, Pb):
After mixing (Sr, Ba): Ca: Cu in a ratio close to 2: 2: 2: 3, 700 in a non-oxidizing atmosphere
The most basic constitution is one produced by heat treatment at a temperature of ˜830 ° C.
i, Pb) :( Sr, Ba): Ca: Cu is 2: 2:
After mixing so as to have a ratio close to 1: 2, the mixture is heat-treated at a temperature of 700 to 830 ° C. in a non-oxidizing atmosphere to obtain no (Ca, Sr) ₂ PbO ₄ compound (Bi.
_{1-x Pb x) 2 (} Sr 1-y Ba y) 2 CaCu 2 O 10- δ
System raw material powder is manufactured in advance, and this raw material powder and Ca-Sr-
A Cu-O-based compound may be mixed to form a raw material mixed powder. The Ca-Sr-Cu-O-based compound basically does not contain Pb, but may contain a trace amount of Pb.

The raw material powder used in the present invention is P
Bi not including b₂ (Sr_1-y Ba _y )₂ CaCu₂ O
_Ten- δ (however, 0 ≦ y ≦ 0.2) system powder and Ca-Pb
-Sr-Cu-O-based compound powder is prepared separately,
These are (Bi, Pb) :( Sr, Ba): Ca: Cu
Were mixed so that the ratio was close to 2: 2: 2: 3.
After that, heat treatment at a temperature of 700 to 830 ° C. in a non-oxidizing atmosphere
(Bi_1-x Pb_x)₂ (Sr_1-y Ba_y )₂ Ca
Cu₂ O_Ten- δ (however, 0.05 ≦ x ≦ 0.7, y is before
The same meaning) as the superconducting phase
Raw material mixed powder can also be used. Raw materials like this
The powder may be adjusted in the sheath material. That is, Pb
Bi not including₂ (Sr_1-y Ba_y)₂ CaCu₂ O_Ten- 
δ (where 0 ≦ y ≦ 0.2) -based raw material powder and Ca-Pb
-Sr-Cu-O-based compound powder is prepared separately,
These are (Bi, Pb) :( Sr, Ba): Ca: Cu
Are mixed in a ratio close to 2: 2: 2: 3.
After enclosing it in a sheath material, 700 ~ in a non-oxidizing atmosphere
Heat treatment was performed at a temperature of 830 ° C., and (Bi_1-xP
b_x)₂ (Sr_1-y Ba_y )₂ CaCu₂ O_Ten- δ (however
, 0.05 ≤ x ≤ 0.7, y has the same meaning as before)
As a raw material mixed powder in which a superconductor phase having a structure is generated
After that, the sheath material is subjected to plastic working,
The object of the present invention is achieved even if heat treatment is performed in a non-oxidizing atmosphere.
Is made.

By the way, the Bi-based oxide superconductor according to the present invention basically contains Pb, because the Bi-2223 phase is not generated unless Pb is included. This Pb is obtained by substituting 5 to 70 atomic% of Bi and forming a solid solution (0.05 ≦ x ≦ 0.7). For example, (Bi _1-x P
For _{b x) 2 Sr 2 CaCu 2} O 10- δ, solid solution amount of Pb is characterized by the lattice constant of the crystal. That is,
_{(Bi 1-x Pb x)} 2 Sr 2 CaCu 2 O 10- δ lattice constant when the crystal structure of the tetragonal of 5.395 <a, b <
5.430 (Å), 30.58 <c <30.90 (Å)
, The lattice constant is 5.395 <in the case of orthorhombic crystal.
a <5.445, 5.390 <b <5.440, 30.
It is in the range of 58 <c <30.95 (Å). Further, the Bi-based oxide superconductor according to the present invention includes one in which a part of Sr (20 atomic% or less, that is, 0 ≦ y ≦ 0.2) is replaced with Ba, but the presence or absence of Ba is a superconducting property. Has almost no effect.

The compound used in preparing the raw material powder in the present invention is not particularly limited, but for example, Bi ₂ O ₃ , Pb ₂ O ₃ , SrCO ₃ , CaCO ₃ ,
Examples thereof include oxides and carbonates such as CuO, and nitrates of each constituent element. The sheath material used when applying the sheath method is not particularly limited as long as it can diffuse oxygen, and examples thereof include silver, a silver alloy, and gold. Furthermore, finally in the sheath material, Bi-2223 is used.
The atmosphere in which the phase is generated may be either the air or a non-oxidizing atmosphere, and the temperature at that time is 830 to 8
It is about 50 ° C. However, the Bi-2223 phase generation temperature when not enclosed in the sheath material is a slightly higher temperature range.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification of the design in view of the spirit of the preceding and the following will be technical technical aspects of the present invention. It is included in the range.

[0020]

【Example】

Example 1 Bi ₂ O ₃ , Pb ₂ O ₃ , and SrC having a purity of 99.9% or more
Powders of O ₃ , BaCO ₃ , CaCO ₃ , and CuO were used, and the molar ratio of each element was Bi: Pb: Sr: Ba: Ca :.
Cu = 1.9: 0.3: 1.9: 0.1: 2.0: 3.
The mixture was weighed and mixed so that the ratio became 0: and the first calcination was performed at 750 ° C. in the atmosphere, then, this was crushed and calcined at 800 ° C. for 48 hours.

After the obtained calcined powder was pulverized again, the diameter:
Disc-shaped pellets of about 2 cm and thickness: about 3 mm,
This was heat-treated at 800 ° C. for 18 hours in an Ar atmosphere. FIG. 1 shows an XRD pattern of the raw material powder calcined at 800 ° C. in an Ar atmosphere. When the raw material powder is calcined in an Ar atmosphere, (Ca, Sr) ₂ PbO ₄ does not exist at all in the sample, Pb is solid-solved in the Bi-2212 phase, and Pb ²⁺
It can be seen that it exists in the state of.

This sample was crushed to a size of 53 μm or less, packed in a silver pipe (sheath material), drawn and rolled, and then heat-treated in the atmosphere at a temperature range (830 ° C.) where a Bi-2223 phase was formed. . Fig. 2 shows the XRD pattern of the powder in the silver sheath material after firing once, and Fig. 3 shows the magnetic susceptibility (X
The result of g) is shown. From these figures, the Bi-2223 phase is contained in the silver sheath material in a volume fraction of about 8 by one heat treatment.
It can be seen that 0% or more is generated.

After this, the wire was pressed at a pressure of about 7 ton / cm ² and heat-treated again at 830 ° C. FIG. 4 shows the XRD pattern of the powder in the silver sheath material after the heat treatment twice.
The magnetic susceptibility measurement of the powder is shown in each. From these figures,
Bi-2223 phase as a main component by two heat treatments,
It can be seen that a wire containing a small amount of the Bi-2212 phase and the (Ca, Sr) ₂ PbO ₄ compound was obtained.
In comparison with the comparative example described later, in the case of the silver sheath wire produced by the conventional method, the Bi-2223 phase was not sufficiently generated by the two treatments, whereas in the present invention, the B-2223 phase was almost not produced by the two treatments.
The i-2223 phase is a single phase. From this, Bi-
It can be seen that the production rate of the 2223 phase was dramatically improved by the present invention. The Jc of this wire is 35,000A /
It was cm ² (77K, 0T).

Example 2 The molar ratio of elements is Bi: Pb: Sr: Ba: Ca: Cu =
A raw material powder of 1.8: 0.4: 2.0: 2.0: 3.2: was produced by the same method as above, and a silver sheath wire rod was produced using this raw material powder. When this wire was heat-treated at 835 ° C., pressed at a pressure of about 7 ton / cm ² , and then heat-treated again at 835 ° C., the Bi-2223 phase almost became a single phase. The Jc of the wire at this time was 34,000A.
/ Cm ² (77K, 0T).

Comparative Example Bi ₂ O ₃ , Pb ₂ O ₃ and SrC having a purity of 99.9% or more
O ₃ , BaCO ₃ , CaCO ₃ , and CuO powders were used, and the molar ratio of these elements was Bi: Pb: Sr: B.
a: Ca: Cu = 1.9: 0.3: 1.9: 0.1:
Weighed and mixed so as to be 2.0: 3.0 :, and 750 in air
After calcination for the first time at ℃, crush this, 800 ℃
It was calcined for 48 hours.

After the obtained calcined powder was pulverized again, the diameter:
Disc-shaped pellets of about 2 cm and thickness: about 3 mm,
This was heat-treated in the air at 830 ° C. for 24 hours. FIG. 6 shows the XRD pattern of this raw material powder. From this figure, it can be seen that Bi-2212 phase, (Ca, Sr) ₂ P is contained in this raw material powder.
bO ₄ , (Ca, Sr) ₂ CuO ₃ , CuO, trace B
It can be seen that the i-2223 phase is present.

After pulverizing this powder to 53 μm or less, it was packed in a silver pipe (sheath material) and subjected to wire drawing and rolling to prepare a tape wire material, which was heat-treated in the atmosphere at 830 ° C. for 72 hours. Fig. 7 shows the X of the powder in the silver sheath material after firing once.
The RD pattern is shown in FIG. 8, and the magnetic susceptibility of the powder is shown.
From these figures, it can be seen that the Bi-2223 phase is not so much produced in the single firing, but the Bi-2212 phase is mainly produced.

After that, the wire was pressed at a pressure of about 7 ton / cm ² and heat-treated again at 830 ° C. for 72 hours. Figure 9
10 shows the XRD pattern of the powder in the silver sheath material after the heat treatment twice, and FIG. 10 shows the magnetic susceptibility of the powder. From these figures, it can be seen that although the production amount of the Bi-2223 phase is increased by performing the heat treatment twice, the Bi-2212 phase and the impurity phase still remain. The Jc of this wire is about 8000 A / cm ² (77K, 0T), which is a considerably smaller value than the Jc of the wire of the above embodiment.

The wire was further pressed at a pressure of about 7 ton / cm ² and then heat-treated at 830 ° C. for 72 hours.
As a result, the impurity phase was reduced, and the Bi-2223 phase was almost single phase. FIG. 11 shows the XRD pattern of the powder in the silver sheath material after firing three times, and FIG. 12 shows the magnetic susceptibility of the powder. From these results, by heat treatment three times,
It can be seen that the Bi-2223 phase is almost a single phase in the silver sheath material. However, the Jc of this wire is 25,0
The value was 00 A / cm ² (77 K, 0 T), which was considerably lower than that of the example.

[0030]

The present invention is constructed as described above, and in the sheath material, the Bi-2223 phase requires half the time and half of the conventional method.
A single-phase press could produce a wire having almost a single phase and a high Jc. Further, the wire rod obtained by the present invention is optimal as a material for a superconducting magnet and the like.

[Brief description of drawings]

FIG. 1 is an XRD pattern of raw material powder after calcination in Example 1.

FIG. 2 is an XRD pattern of the powder in the silver sheath material after firing once in Example 1.

FIG. 3 is a graph showing the magnetic susceptibility of the powder in the silver sheath material after firing once in Example 1.

FIG. 4 is an XRD pattern of powder in the silver sheath material after heat treatment twice in Example 1.

FIG. 5 is a graph showing the magnetic susceptibility of the powder in the silver sheath material after heat treatment twice in Example 1.

FIG. 6 is an XRD pattern of raw material powder after calcination in a comparative example.

FIG. 7 is an XRD pattern of the powder in the silver sheath material after firing once in the comparative example.

FIG. 8 is a graph showing the magnetic susceptibility of the powder in the silver sheath material after one-time firing in the comparative example.

FIG. 9 is an XRD pattern of the powder in the silver sheath material after the heat treatment was performed twice in the comparative example.

FIG. 10 is a graph showing the magnetic susceptibility of the powder in the silver sheath material after the heat treatment was performed twice in the comparative example.

FIG. 11 is an XRD pattern of powder in a silver sheath material after firing three times in a comparative example.

FIG. 12 is a graph showing the magnetic susceptibility of the powder in the silver sheath material after firing for 3 days in the comparative example.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01L 39/24 ZAA Z 9276-4M

Claims (6)

[Claims] 1. A sheathing method for a Bi-based oxide superconductor wire rod.
Therefore, when manufacturing (Bi_1-x Pb_x )₂ (Sr
_1-y Ba_y )₂ CaCu₂ O_Ten- δ (however, 0.05 ≦
x ≦ 0.7, 0 ≦ y ≦ 0.2) powder having a chemical structure
And a Ca-Sr-Cu-O-based compound powder, and
One (Ca, Sr)₂ PbO_Four Raw material mixture containing no compounds
The powder is mixed with (Bi, Pb) :( Sr, B in the mixed powder.
a): Ca: Cu becomes a ratio close to 2: 2: 2: 3
Prepared in advance, and then mix this powder with the sheath material.
In the air or after non-oxidizing
The mixed powder in the sheath material (B
i, Pb)₂ (Sr, Ba) ₂ Ca₂ Cu₃ O-type oxide
Bi-based oxide superconductor characterized by having a superconductor phase
Manufacturing method of body wire. 2. The raw material mixed powder used in the manufacturing method according to claim 1, is a Bi compound, a Pb compound, a Sr compound, or B.
The a compound, the Ca compound and the Cu compound are (Bi, P
b) :( Sr, Ba): Ca: Cu are mixed in a ratio close to 2: 2: 2: 3, and then heat treated at a temperature of 700 to 830 ° C. in a non-oxidizing atmosphere. A raw material powder for producing a Bi-based oxide superconductor wire rod. 3. When manufacturing a Bi-based oxide superconducting wire by a sheath method, (Bi _1-x Pb _x ) ₂ (Sr
_{1-y Ba y) 2 CaCu} 2 O 10- δ ( where, 0.05 ≦
(x ≦ 0.7, 0 ≦ y ≦ 0.2) and a raw material powder containing no (Ca, Sr) ₂ PbO ₄ compound and a Ca—Sr—Cu—O compound powder are separated. And prepare them in (Bi, Pb) :( Sr, Ba): C
After mixing a: Cu in a ratio close to 2: 2: 2: 3, the mixture is sealed in a sheath material, plastically processed, and heat-treated in the atmosphere or a non-oxidizing atmosphere to remove the heat from the sheath material. The mixed powder was mixed with (Bi, Pb) ₂ (Sr, Ba) ₂ Ca ₂ Cu.
_A method for producing a Bi-based oxide superconductor wire, which comprises a ₃ O-type oxide superconductor phase. 4. Use in the manufacturing method according to claim 3 (B
_{i 1-x Pb x) 2} (Sr 1-y Ba y) 2 CaCu 2 O
_{The 10-} δ type raw material powder contains Bi compound, Pb compound, Sr compound, Ba compound, Ca compound and Cu compound,
(Bi, Pb) :( Sr, Ba): Ca: Cu is 2:
Raw material powder for producing a Bi-based oxide superconductor wire rod, which is produced by mixing in a ratio close to 2: 1: 2 and then heat-treating at a temperature of 700 to 830 ° C. in a non-oxidizing atmosphere. . 5. When manufacturing a Bi-based oxide superconducting wire by a sheath method, Bi ₂ (Sr containing no Pb is used).
_{1-y Ba y) 2 CaCu} 2 O 10- δ ( where, 0 ≦ y ≦
0.2) -based raw material powder and Ca-Pb-Sr-Cu-O-based compound powder are separately prepared, and these (Bi, P
b) :( Sr, Ba): Ca: Cu are mixed in a ratio close to 2: 2: 2: 3, and then heat-treated at a temperature of 700 to 830 ° C. in a non-oxidizing atmosphere (Bi _{1 -x} Pb
_{x) 2 (Sr 1-y} Ba y) 2 CaCu 2 O 10- δ ( where, 0.05 ≦ x ≦ 0.7, y is to produce a superconductor phase having the chemical structure of the same meaning) as before The raw material mixed powder is sealed in a sheath material, subjected to plastic working, and then heat-treated in the air or in a non-oxidizing atmosphere to convert the raw material mixed powder in the sheath material to (Bi, Pb) ₂ (Sr, Ba). ) ₂ C
An a ₂ Cu ₃ O type oxide superconductor phase is provided, which is a method for producing a Bi-based oxide superconductor wire. 6. When manufacturing a Bi-based oxide superconducting wire by a sheath method, Pb-free Bi ₂ (Sr
_{1-y Ba y) 2 CaCu} 2 O 10- δ ( where, 0 ≦ y ≦
0.2) -based raw material powder and Ca-Pb-Sr-Cu-O-based compound powder are separately prepared, and these (Bi, P
b) :( Sr, Ba): Ca: Cu are mixed so as to have a ratio close to 2: 2: 2: 3, and this is sealed in a sheath material, and then the mixture is heated at 700 to 830 ° C. in a non-oxidizing atmosphere. Heat treatment at temperature, and in the sheath material (Bi _1-x Pb _x ) ₂ (Sr _{1-y
Ba y) 2 CaCu 2 O 10-} δ ( where, 0.05 ≦ x ≦
0.7, y is the same meaning as before), after forming a raw material mixed powder in which a superconductor phase having a chemical structure is generated, the sheath material is subjected to plastic working, and subsequently heat treated in the atmosphere or a non-oxidizing atmosphere. The mixed powder in the sheath material (Bi, Pb)
₂ (Sr, Ba) ₂ Ca ₂ Cu ₃ O-type oxide superconductor phase is used for producing a Bi-based oxide superconductor wire.