JPS63257132A - Manufacture of oxide superconductor - Google Patents

Abstract

PURPOSE:To obtain the good superconductive characteristic by using specific soluble organic metals to hydrolyze, forming the sol material thus obtained into a gelatinous molding directly or via another base material, and sintering this gelatinous molding to form a composite metal oxide. CONSTITUTION:The preset quantity of soluble organic metals expressed by formulas M1(OR1)3, M2(OR2)2, Cu(OR3)2 is dissolved in a water-soluble organic solvent to form a sol by hydrolysis, the sol material thus obtained is formed into a gelatinous molding directly or via another base material. Next, the gelatinous molding thus obtained is dried then heated and sintered to form a composite metal oxide. In the formulas, M1 is the rare earth element of the IIIa group, M2 is the alkaline earth metal of the IIa group, R1-R3 are the groups combined or coordinated with M1 or M2 such as the low-grade alkyl group or alkyl carbonyl group or acetyacetone base and dissolved in a water-soluble organic solvent. A superconductor excellent in the superconductive characteristic is efficiently obtained accordingly.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing an oxide superconductor.

[Conventional technology and its problems]

Conventionally, there are various types of oxide-based superconductors, but for example, a method for producing a La-Ba-Cu-0-based oxide is to weigh the required amount of powder of Lag 03 , BaC0z , and CuO, knead it with water, etc. , after forming into a cylinder or disk,
A method of sintering at a temperature around 1000°C is used.

The biggest problem with this manufacturing method is that it is completely impossible to process it into a sintered ridge shape due to mechanical fragility, which is a common characteristic of oxide superconductors. In addition, compacts made from oxides have poor sinterability, and even if a linear compact is obtained, it is difficult to maintain the shape after the sintering process, and even if the shape can be maintained, it is difficult to maintain the shape. There are many problems, such as the need to grind and mix oxides for a long time to make them fine.

[Means and effects for solving the problems] As a result of various studies regarding the above-mentioned problems, the present invention has developed an efficient method for manufacturing oxide-based superconductors that has good sinterability and can be formed into linear, tubular, etc. A good manufacturing method has been developed.

That is, the present invention is a process of dissolving a predetermined amount of each soluble metal represented by the general formula (%) in a water-soluble organic solvent, and forming a sol by hydrolysis, and directly dissolving the obtained sol. or a step of forming a gel-like molded product through another base material, a step of drying the obtained gel-like molded product, and a step of heating and sintering the dried gel-like molded product to form a composite metal oxide. This is a method for producing an oxide-based superconductor characterized by the following.

In the above general formula, Ml is ma of Y, La, Sc, etc.
Group rare earth elements, Ml is I'l such as Ca, Sr, Ba, etc.
Group a alkaline earth metal, R,, R,, R1 is H or C
Lower alkyl groups such as H3, CzHs, C1Ht, C4H9 or HCOlCH.

It is an alkylcarbonyl group such as C-0, CzHsCO, or a group such as an acetylacetone residue of C, H, O, etc., or a group that can be combined with or coordinated with M1 and dissolved in a water-soluble organic solvent.

In the above, water-soluble Ia solvents include alcohols such as methyl alcohol and ethyl alcohol, ketones such as acetone, organic acids such as acetic acid, and amines such as hydrazine. After dissolving a predetermined amount of each of the three types of organic metals represented by the above general formula in a solvent, hydrolysis is performed to generate hydroxides of rare earth elements, alkaline earth metals, and copper in the form of a sol, and in the sol state. It is formed into a fiber, film, pipe, rod, etc., dehydrated and condensed to form a gel, and then heated and sintered to form an oxide-based superconductor.

In addition, a tantalum-coated copper wire or a base metal or barrier material used in ordinary superconducting wires is used as a base material, and a sol compound is attached in a film form to this, and through the above steps, an oxide-based superconductor is obtained. You can also do that.

In the present invention, oxide particles are obtained by dehydrating and heating hydroxide particles suspended in a sol state, so each oxide is finely and homogeneously distributed, and a good Superconducting properties can be obtained.

Therefore, the oxide-based superconductors targeted in the present invention include La-Ba-Cu-0 system, Y-Ba-Cu-0 system, 5
c-Ba-Cu-0 series and other Ma group rare earth elements - Ua group alkaline earth metals - Cu-0 series oxides, etc., and the composition is, for example, (II a + II a)
tc u Oa−δ or (II[a+U a)s C
There is a composition represented by uzot-δ.

Next, one embodiment of the present invention will be explained. As shown in FIG.
Dissolve a predetermined amount of each type of machine metal, add water and stir to form a sol-like suspension 1. This is heated and dehydrated to form a polymer gel, which is then molded by its own weight or under pressure into a die 2. It is extruded and molded into a desired shape and size, dried in a drying oven 3, wound up on a reel 4, and heated and sintered to form a superconductor.

However, when water is added to methyl alcohol in which the three types of organic metals represented by the above general formula are dissolved, for example, La(OH)3, B a (OH)z
In order to obtain hydroxides such as Cu(OH)z, the blending ratio is: total amount of compounds subjected to dissolution: methyl alcohol:
Water = 0.1~a:O, t~3:0.1~8 is suitable, the dehydration condensation temperature is preferably 50~150°C, and the sintering temperature is in the range of 500°C~1800°C. It has excellent sinterability and is suitable for use.

Adding a small amount of an acid such as HCI or an alkali such as ammonia to water as a catalyst accelerates hydrolysis.

When the suspension after hydrolysis is stirred, a chain or network polymerization reaction proceeds between the hydroxides, and the viscosity increases to between 10 and 10 voids, making it possible to perform shaping such as spinning. If the viscosity is insufficient, use sodium alginate, allyl urea,
A soluble organic thickener such as amerine, carboxymethyl cellulose or polyvinyl alcohol may be added.

〔Example〕

An embodiment of the present invention will be described below.

Example-1 Ethyl alcohol 11, L a (OCzHs)*, B
a (OC2H3)z and Cu(OH)z each at 7
．． 00g.

After 0.72 g and 3.84 g were dissolved and mixed well, 35 d of water containing HCI at a concentration of 0.11 d#2 was added and stirred to form a sol-like suspension. The viscosity increased with stirring, and a small amount of carboxymethyl cellulose sodium salt (0.5 g) as a thickener was added thereto to form a string.

Next, add this to 0.2 mI! 100 from +φ spinning nozzle
A sol fiber was obtained by extrusion into a drying chamber at °C, and this was further dried to obtain a gel fiber. During drying, the temperature in the drying room was kept low to avoid cracks or cavities in the fibers. This fiber was further heated in an atmospheric heating furnace at 800''C for 5 hours to form an oxide superconductor, and immediately coated with urethane resin for reinforcement.

Example-2 L a (CI(3COO)3, B
3.5 g each of a (CH3Coo)t and CLI(CH,C00)2.

After melting 0.4 g and 1.9 g and mixing well, 30 m of water containing HCI at a concentration of O, Ld/1 was added and stirred to form a sol-like suspension. This was made into an oxide-based superconductor reinforced with urethane resin by the same method as in Example 1.

Conventional example-1 On the other hand, as a conventional example, I, ago, , BaCO3CuO
The powder of La: Ba: Cu=3.55:0.4
4:2.5, water was added to this to make a slurry, passed through a die with 0.2 om holes, and 10
Extruded into a drying chamber at 0°C, the fiber was further dried at 80°C.
The superconducting wire was heated in an atmospheric heating furnace at 0°C for 5 hours.

The results of characteristic tests on these superconducting wires are presented in the first
Shown in the table.

Table 1 As is clear from Table 1, according to the present invention, a significantly longer wire rod than the conventional wire rod was obtained, and an oxide-based superconducting wire with excellent bending strain characteristics and superconducting characteristics was obtained.

Example-3 La (CHa COO) 3, Ba in 200 d of acetic acid
(CHxCoo)x, Cu (CHzCOO)t, 4.05 g each.

After dissolving 0.41 g and 3.57 g and mixing well,
Water containing HCI at a concentration of O, 1 m/ffi was
ml was added and stirred to obtain a sol-like suspension. Separately, a copper wire coated with tantalum and having an outer diameter of 0.5 mm was prepared.

As shown in FIG. 2, the tantalum coated copper wire 6 is passed through the sol-like suspension 5 to cause the sol to adhere to the surface.
This was dried in a drying oven 7 at 80°C, shaped and compressed using a cassette roller die 8, and then passed through a drying oven 9 at 190°C to have an outer diameter of 0.6 mmφ.

This was finally heated and sintered at 950°C for 6 hours to obtain a superconducting wire. Figure 3 shows its cross-sectional view. Copper wire 10 is coated with tantalum 11, and oxide-based superconductor 12 is formed thereon.

Conventional Example-2 On the other hand, as a conventional example, powders of LazO3 and BaCO3CuO were prepared as follows: La: Ba: Cu=1.78:0.22:
1.25, add water to this mixed powder to make a slurry, and add tantalum-coated powder with an outer diameter of 0.
．． A copper wire with a diameter of 5 mm was passed through a die having an inner diameter of 0.6 sn φ, dried at 80''C-190°C, and then heated and sintered at 950°C for 6 hours to obtain a superconducting wire.

Characteristic tests were conducted on these superconducting wires.

The results are shown in Table 2.

As is clear from Table 2, the surface superconducting layer of the superconducting wire obtained by the present invention is extremely difficult to peel off (and both the superconducting start temperature and superconducting end temperature are significantly higher than those obtained by the conventional method). It was confirmed that the material exhibited excellent properties.

〔Effect of the invention〕

As explained above, according to the present invention, a long, seed-shaped oxide superconductor with excellent mechanical properties and superconducting properties can be efficiently obtained, and furthermore, the oxide superconductor can be formed on a base material. The material formed by this method has excellent workability and adhesion, and has a significant industrial effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing an oxide-based superconducting wire showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a method for forming an oxide-based superconductor on a tantalum-coated copper wire, showing another embodiment. FIG. 3 is a cross-sectional view of the above-mentioned formed body. 1.5...Sol suspension, 2...Dice, 3.
... Drying oven, 4... Reel, 6... Tantalum coated copper wire, 7.9... Drying oven, 8... Cassette roller') E, 0... Copper wire, 11...・Tantalum, 12...Oxide-based superconductor.

Claims (3)

[Claims] (1) General formula M_1 (OR_1
)_3, M_2(OR_2)_2, Cu(OR_3)_
2 (in the formula, M_1 is a group IIIa rare earth element, M_2 is IIa
R_1, R_2, R_3 are H or lower alkyl groups, or a group of groups that can be combined or coordinated with M_1 such as alkyl carbonyl groups and acetylacetone residues to dissolve in water-soluble organic solvents. Same or different groups selected from. ) A step of dissolving a predetermined amount of each soluble organometallic substance and forming it into a sol by hydrolysis, a step of forming the obtained sol directly or through another base material into a gel-like molded product, A method for producing an oxide superconductor, comprising the steps of drying a gel-like molded product, and heating and sintering the dried gel-like molded product to form a composite metal oxide. (2) The method for producing an oxide superconductor according to claim 1, wherein the gel-like molded product is in the form of a fiber, film, pipe, or rod. (3) The method for producing an oxide-based superconductor according to claim 1, wherein the base material is a tantalum-coated copper wire, or a base metal or barrier material used in ordinary superconducting wires.