JPH0196016A - Starting material for conjugate oxide superconductor and production thereof - Google Patents

Abstract

PURPOSE:To obtain a high purity uniform starting material for a conjugate. oxide superconductor having high reactivity by spray-drying a suspension prepd. by suspending the oxide of an element selected among rare earth elements including Y, an org. acid salt of Cu, etc., in a solvent. CONSTITUTION:The oxide of an element selected among rare earth elements including Y, an org. acid salt of an element selected among alkaline earth metals and Pb, and an org. acid salt of Cu are suspended in a solvent to prepare a suspension. This suspension contg. the starting materials for a conjugate. oxide superconductor is spray-dried.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a composite oxide superconductor raw material and a manufacturing method.

[Conventional technology]

In 1986, a La-Ba-Cu-0 material with a critical temperature Tc of 30 to 40K was announced, and 19
In February 1987, Y-Ba-Cu had a Tc of 90 or more.
-0-based composite oxide superconductors have been discovered, and research into practical use is progressing.

These superconductors are manufactured through a process of calcining, pulverizing, and shaping and sintering raw material powder. In order to obtain high superconducting properties, it is necessary to manufacture a highly pure and highly reactive homogeneous raw material powder. It is essential to do so.

Conventionally, superconductor raw material powder has generally been produced by a powder method in which powders of constituent oxides or carbonates are used as starting materials, weighed in predetermined proportions, and mixed in a ball mill or the like.

The finer the particles of the starting material, the higher the homogeneity of the raw material powder produced by this method. However, the particle size of these starting materials is usually as coarse as 1 to 371 m, and particularly when CuO, which is difficult to obtain fine particles as a copper raw material, is used, the homogeneity is significantly reduced. Therefore, a superconductor manufactured from this raw material powder has a foreign phase and its properties are poor.

Conventionally, in order to avoid this heterogeneous structure, coprecipitation methods and sol
Production is also carried out by solution methods such as gel methods.

Although these methods are superior to the powder method in terms of purity and uniformity, they have the following problems6: ■ The coprecipitation method uses chemicals such as alkalis as precipitants, so they are It remains in the powder and has a detrimental effect on superconducting properties. Furthermore, in order to co-precipitate cations at a target composition ratio, delicate adjustment of the pH of the solution is required, which tends to cause a one-component deviation.

■ In both the coprecipitation method and the sol-gel method, the solubility of barium nitrate, one of the raw materials, in solvents such as water and ethanol is low, and only dilute solutions can be obtained, so it takes a long time to precipitate a large amount of raw material powder. It takes.

Spray-drying and freeze-drying have the advantage of not causing compositional deviations like the coprecipitation method, being able to obtain a large amount of raw material powder in a short time, and being easily scaled up to commercial scale. There are the following problems when producing raw material powder for composite oxide superconductors.

(1) When spray-drying or freeze-drying a suspension of an insoluble metal source, the homogeneity of the suspension is controlled by the particle size of the starting material, as in the powder method, and fine powders such as CuO are obtained. If difficult starting materials are used, the homogeneity will be significantly degraded.

(2) When spray-drying or freeze-drying a solution of a soluble metal source in a solvent such as water or ethanol, (i) soluble salts of rare earth metals are expensive and difficult to obtain; nitrates, which are relatively cheap, dry N that is harmful to the human body during subsequent calcination
Ox is generated.

(ii) In general, only a dilute solution with a saturation concentration or less can be obtained, so drying takes time, and the powder particles obtained by drying are not dense and have low reactivity.

As described above, with conventional techniques, it has been difficult to produce uniform, highly pure, and highly reactive composite oxide superconductor raw materials in large quantities in a short period of time.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the problems of the above-mentioned conventional technology and provide a method for producing uniform, highly pure, and highly reactive composite oxide superconductor raw materials in large quantities in a short time.
To this end, it is an object of the present invention to provide a useful raw material for spray drying or freeze drying (suspension).

[Means for solving problems]

The composite oxide superconductor raw material suspension of the present invention contains an oxide of one or more elements selected from rare earth metal elements including 7Y, and one element selected from alkaline earth metals and Pb. Alternatively, it is a composite oxide superconductor raw material suspension prepared by mixing an organic acid salt of two or more elements, an organic acid salt of Cu, and a solvent.

In addition, the method for producing the composite oxide superconductor raw material includes one or more elements selected from rare earth metal elements including Y, and one or more elements selected from alkaline earth metals and Pb. In a method for producing a composite oxide superconductor containing elements and Cu as essential components, an oxide of a component element selected from rare earth elements including Y and an organic acid salt of another component element are mixed using a solvent. This is a method for producing a raw material for a composite oxide superconductor, which is characterized by: (1) spray-drying the suspension, and (2) freeze-drying the suspension.

[Effect]

In the present invention.

(a) Rare earth metal sources containing Y include Y2O3゜E u20
(b) A soluble organic acid salt such as a water-soluble carboxylate is used as a metal source of a component element other than the rare earth.

These metal sources are weighed in a predetermined ratio and wet-mixed using an organic solvent such as water, ethanol, n-propanol, or ethylene glycol to form a suspension and prepare a uniform raw material.

Next, the following method is used to obtain composite oxide superconductor raw material powder from this suspension.

■ Obtain dry powder by spraying into hot air using a nozzle or rotary atomizer (spray drying method).

■ After freezing by spraying on a refrigerant such as liquid nitrogen, it is sublimed in a vacuum to obtain a dry powder (freeze-drying method).

The superconductor raw material powder thus obtained was heated to 900°C to 100°C.
The calcined powder obtained by calcining at 0℃ and further pulverizing with a ball mill etc. is press-molded or formed into a linear shape by a sheath method, extrusion method, etc., and then calcined at a temperature range of 900 to 1030℃. A composite oxide superconductor can be obtained. In the case of spray drying, it is also possible to perform spray drying and calcining in one step using a spray pyrolysis method.

In the present invention, oxides are used as the rare earth metal source containing Y because oxides with high purity, very small particle size, and low cost are commercially available.

The reason why a soluble organic acid salt was used as a source of metals other than rare earths is as follows.

■ These have the advantage that they can be easily purified by recrystallization from solvents such as water, making it easy to obtain products of extremely high purity.

■ Since it is an ionic crystal, even the saturated portion remaining in the solvent is crushed into very fine particles during mixing by arm opening.

Therefore, compared to the conventional powder method that uses oxide or carbonate powder as raw materials, it is possible to obtain superconductor raw material powder that is much more uniform and highly pure.

In the present invention, in order to spray-dry or freeze-dry a suspension with a very high concentration exceeding the saturation concentration of the metal salt in the solvent used, the conventional method of spraying and freeze-drying a dilute solution with a saturation concentration or less, or the sol - Much more time efficient than the gel method.

In addition, the raw material powder produced has a more homogeneous composition and denser particles than the conventionally most common powder method, and there is no composition shift as in the coprecipitation method. The composite oxide superconductor has a higher critical temperature (Tc) and higher reliability than the conventionally most commonly used powder method.

■ High reactivity, short sintering time, and no non-superconducting impurity phases such as unreacted raw materials or intermediate products remain.

■ Since there is no non-superconducting phase, the critical current value (J c
) is high.

It has the characteristics of

As described above, according to the method of the present invention, it is possible to produce a large amount of composite oxide superconductor having a uniform composition, high purity, and high reactivity in a short time.

In addition, in the present invention, the homogeneity of the suspension is improved by adding a dispersant such as ammonium polyacrylate, which can be used as a dispersant to disperse particles in the suspension, and the raw material to be manufactured is The properties of the powder are also further improved.

〔Example〕

Example-1 Yttrium oxide (average particle size IBm), barium acetate,
Copper acetate hemihydrate was weighed so that the molar ratio of Y:Ba:Cu=1:2:3. This mixture has a suspension concentration of 50
% of distilled water, mixed for 12 hours in a rotary ball mill, and then heated at 150°C using a 70gmfl nozzle.
The powder was spray-dried in hot air to obtain a raw material powder for a composite oxide superconductor. This was calcined at 900°C, added with n-propanol, pulverized in a rotating ball mill, dried, press-molded, and fired in air at 950°C for 20 hours to form a superconductor YBa.
2Cu30y was obtained (sample 1-1).

In addition, 1% by weight of ammonium polyacrylate was added to the same suspension as above, and the superconductor YBa2C was prepared using the same process.
u30y was obtained (sample 1-2).

Comparative Example ~l Yttrium oxide with an average particle size of 1 μm, barium carbonate with an average particle size of 1 μm, and cupric oxide powder with an average particle size of 3 JLm in a molar ratio of Y:Ba:Cu=1:2:3 (7) The mixture was weighed, n-propertool was added thereto, mixed in a rotating ball mill, and dried by holding at 100° C. for 12 hours to obtain a raw material powder for a composite oxide superconductor. This was calcined at 900°C, added with n-propertool, pulverized in a rotary ball mill, dried, then press-molded and heated to 950°C in the air for 2 hours.
After firing for 0 hours, a superconductor YBa2Cu30y was obtained (comparative sample 1).

Example 2 Eu2O3 having an average particle size of lm, barium acetate, and copper acetate hemihydrate were weighed so that the molar ratio of Eu:Ba:Cu=1:2:3. Thereafter, a superconductor EuBa2 Cu30y was obtained in the same steps as in Example 1 (sample 2-1).

In addition, a superconductor ErBa2 Cu30y was obtained in the same process using Er203 instead of Eu20g (sample 2).
-2).

Comparative Example-2 Eu2O3 with an average particle size of lm and BaC with an average particle size of lm
O3 and CuO with an average particle size of 3ILm, Eu:Ba:Cu
They were weighed so that the molar ratio was 1:2:3. In the following steps similar to Comparative Example 1, the superconductor EuBa2 Cu3 oy
was obtained (comparative sample 2-1).

Further, a superconductor ErBa2Cu30y was obtained in the same process using Er203 instead of Eu2O3 (comparative sample 2-2).

Example 3 Using the starting materials and lead acetate used in Example 1, Y:Ba
:Pb:Cu=1: (2-x) :x:3(x=
They were weighed to give a molar ratio of 0.05, 0.1, 0.2, 0.5). Thereafter, a superconductor YBa2-x PbxCu30y was obtained in the same process as in Example 1 (sample 3-
1.3-2.3-3.3-4).

Comparative example-3 Using the starting materials and PbO used in Comparative Example 1.

Y:Ba:Pb:Cu=1: (2-x):x:3(
They were weighed to give a molar ratio of x=0.05, 0.1, 0.2, 0.5). A superconductor YBa2-xPbxCu30y was obtained in the same steps as in Comparative Example 1 (Comparative Sample 3-1.3-2.3-3.3-4).

Example 4 The same suspension as in Example 1 was sprayed into liquid nitrogen using a nozzle with a diameter of 70 m to form frozen particles. This particle is 2
In a vacuum of less than
B a2 Cu3oy was obtained (Sample 4).

Comparative Example-4 Yttrium acetate, barium acetate, copper acetate Y:Ba:
They were weighed so that the molar ratio of Cu was 1:2:3, and distilled water was added until they were completely dissolved, resulting in an aqueous solution with a concentration of 5%. This aqueous solution was sprayed and dried in the same manner as in Example 1 to obtain a raw material powder for a composite oxide superconductor. Using this, the superconductor YBa2 was produced through the same calcination and firing steps as in Example 1.
Cu30y was obtained (comparative sample 4).

Comparative Example-5 Same starting material as Comparative Example 1 with Y:Ba:Cu=1:2:3
The superconductor YBa2Cu30y was obtained in the same process as in Example 1 (comparative sample 5).

Comparative Example-6 Yttrium nitrate, barium nitrate, copper nitrate Y:Ba:
The mixtures were mixed at a ratio of Cu=1:2:3, and distilled water was added to obtain an aqueous solution with a concentration of 5%. Oxalic acid was added to this aqueous solution, and ammonium hydroxide aqueous solution was used as a pH adjuster.
Co-precipitation was carried out while maintaining H=4.6, and the precipitate was filtered and dried to obtain a raw material powder for a composite oxide superconductor. Using this, a superconductor YBa2 cu30y was obtained through the same calcination and firing steps as in Example 1 (comparative sample 6).

Comparative Example-7 A 5% aqueous solution of yttrium nitrate, barium nitrate, and copper nitrate was made as in Comparative Example 6, malic acid and ethylene glycol were sequentially added, and the mixture was stirred and cooled while being held at 90°C for about 4 hours. , a gel-like precipitate was obtained. This temperature is about 300℃
The superconductor raw material powder was obtained by heating and decomposing it.

Using this raw material powder, a superconductor YBa2 Cu30y was obtained through the same calcination and firing steps as in Example 1 (comparative sample 7).
.

Comparative Example-8 Using the same aqueous solution as in Comparative Example 4, a superconductor raw material powder was obtained through the same freeze-drying process as in Example 4. The superconductor YB a7 Cu was formed by the same calcination and firing steps as in Example 1.
30 y was obtained (comparative sample 8).

Among the above samples, the superconductor properties of the YBa2 cu30y composition are shown in Table 1. As is clear from Table 1, according to the present invention, there is no impurity phase and high T
It is possible to produce a superconductor YBa2Cu3O7 with c and Jc.

In addition, Sample 1-2, in which a dispersant was added to the suspension, showed higher properties, indicating that the use of a dispersant in the present invention is extremely effective.

Table 2 shows the YB difference between the production method of the present invention and the conventional solution method.
a2 Cu30 y Production amount of raw material powder and time required for production 0 According to the method of the present invention, it is clear that a large amount of superconductor raw material powder can be produced in a much shorter time than the conventional method.

1 to 4 show comparative photographs of Sample 1-1 (Example) and Comparative Sample 1 (Comparative Example) taken by EPMA (X!i Micro Analyzer).

Figure 1 shows the secondary electron image, Figure 2 (a) shows the Y distribution, Figure 3 shows the Ba distribution, and Figure 4 shows the Cu distribution. ) is a comparative example.

As is clear from FIGS. 1 to 4, according to the method of the present invention, a superconductor with much better homogeneity than the conventional method can be produced.

Table 3 shows 1 produced independently by the process of Example-1.
0 YBa2 cu30y superconductors (sample ti~1
-10) and 10 independently produced by the process of Comparative Example 1.
YBa2Cu30y superconductors (comparative samples 1-1 to 1
-10) The measurement results of the critical temperature Tc are shown.

Table 4 shows the EuBa2 produced in Example 2 and Comparative Example 2.
Table 5 shows the characteristics of Cu30y and E rB a2 Cu30ya conductors.
Shows the superconducting properties of Ba2-)(Pb)(Cu30y).

As is clear from Tables 3 and 4, the method of the present invention can provide much higher superconducting properties with extremely high reliability than the conventional powder method that is commonly used.

In addition, as is clear from the EPMA observation in Table 5, the method of the present invention can produce raw material powder with an extremely homogeneous structure compared to the powder method, so segregation of trace elements does not occur, and when trace amounts of added elements are used, Particularly effective.

〔Effect of the invention〕

As described above, according to the present invention, homogeneous, highly pure, and highly reactive composite oxide superconductor raw material powder can be produced in large quantities in a short period of time.

[Brief explanation of the drawing]

Figures 1 to 4 show the EPMA of Sample 1-1 and Comparative Sample 1 (
This is an element distribution photograph taken at a magnification of 400 times and showing the crystal grain structure using an X-ray microanalyzer. Figure 1 is a secondary electron image, Figure 2 is the distribution of Y, Figure 3 is the distribution of Ba, and Figure 4 is the distribution of C.
EPMA photographs showing the distribution of u, in which (a) is an example (sample 1-1) and (b) is a comparative example (comparative sample 1). \Hehe Stomach-+-1 Fig. 1 (a) Fig. 1 (b) (~i\------N-i\~ Fig. 2 (a) ゛-"-1112-"c −；y゛Figure 3 (a) Figure 3 (b) Figure 4 (a) Figure 4 (1)) Procedures Manual (spontaneous) December 17, 1988 Commissioner of the Patent Office Kuni Ogawa Mr. Husband■, Indication of the case 1986 Patent Application No. 253571 2 Name of the invention Complex oxide superconductor raw material and manufacturing method 3 Person making the amendment Relationship to the case Patent applicant Kitahonmachi-dori, Chuo-ku, Kobe City 1-1-28 (125) Kawasaki Steel Corporation 4, Agent 105 21!03 (508)
4th Floor 5, 2nd Kusuda Building, 1-10-8 Nishi-Shimbashi, Minato-ku, Tokyo 9104, "Detailed Description of the Invention" section of the specification to be amended. 6. Contents of amendment (1) Table 5 on page 21 of the specification will be amended as shown in the attached sheet.

Claims (1)

[Claims] 1. One or two selected from rare earth metal elements including Y.
Oxides of more than one element, alkaline earth metals and Pb
an organic acid salt of one or more elements selected from;
A composite oxide superconductor raw material suspension prepared by mixing an organic acid salt of Cu and a solvent. 2 One or two selected from rare earth metal elements including Y
In the method for producing a composite oxide superconductor having Cu as essential components, one or more elements selected from alkaline earth metals and Pb, a rare earth element selected from rare earth elements including Y, A composite oxide superstructure characterized in that a suspension is prepared by mixing an oxide of a component element and an organic acid salt of another component element using a solvent, and the suspension is spray-dried. Method for manufacturing conductor raw materials. 3 One or two selected from rare earth metal elements including Y
In the method for producing a composite oxide superconductor having Cu as essential components, one or more elements selected from alkaline earth metals and Pb, a rare earth element selected from rare earth elements including Y, A composite oxide superstructure characterized in that a suspension is prepared by mixing an oxide of a component element and an organic acid salt of another component element using a solvent, and the suspension is freeze-dried. Method for manufacturing conductor raw materials.