JPH0812497A - Superconducting material having high levitation and damping characteristics and its production - Google Patents

Abstract

PURPOSE:To obtain a material having high levitation and damping characteristics in a short time by integrating a part at a different dispersed concentration of RE2BaCuO5 phase into a superconducting material containing the RE2BaCuO5 phase dispersed in an REBa2Cu3O7-x. phase. CONSTITUTION:This superconducting material contains an RE2BaCUO5 phase (211 phase) dispersed in a single crystalline REBa2CU3O7-x phase (123 phase) (RE is a rare earth element containing Y or a combination thereof) and further comprises a part At at 5-60% concentration expressed in terms of molar fraction of the 211 phase dispersed in the 123 phase and a part B2 at <5% concentration expressed in terms of the molar fraction of the 211 phase. The concentration of the 211 phase in the part B can be regulated to 0%, i.e., only the 123 phase. Furthermore, this method for producing the superconducting material comprises forming oxides of RE, Ba and Cu into a compact comprising the parts so as to provide the respective molar fractions of the charging composition of the 211 phase in a mixing and a forming steps in a method for production comprising carrying out the mixing, forming, semimelting, seeding, coagulating, cooling and oxygen-enriching heat treatment of the oxides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact levitation device formed of a superconducting material and a magnet, for example, a bearing device for a turbo molecular pump or a flywheel for power storage, a non-contact transfer device in a semiconductor manufacturing process, and removal. The present invention relates to a superconducting material that can be used in a vibration device and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A non-contact levitation device formed of a superconducting material and a magnet is a technique having a large ripple effect, and its future prospect is considered promising. In order to realize this superconducting levitation device, high levitation characteristics and high damping characteristics, which are the ability to damp vibrations, are required. As a superconducting material having a high floating characteristic, that is, a high critical current density (J _C ), REBa ₂ Cu ₃ O ₇ which is a single crystal superconducting phase called a QMG material as disclosed in JP-A-4-40289. _-X
There is an oxide superconducting material in which a RE ₂ BaCuO ₅ phase which is a non-superconducting phase is finely dispersed in the phase. However,
In the high J _C superconducting material, there was a tendency that the damping characteristics became smaller as the levitation force increased. Therefore, conventionally, there has been no superconducting material having high floating characteristics and high damping characteristics.

[0003]

DISCLOSURE OF THE INVENTION In the previous application (Japanese Patent Application No. 6-97933), the inventors of the present invention used a superconducting material of low J _C as a damping material based on an idea which is completely opposite to the conventional one. It was proposed to incorporate it in the levitation device. This is because the levitation function is carried out by a combination of a high J _C superconducting material and a magnet, and the damping function is carried out by a combination of a low J _C superconducting material and a magnet. This technique required the use of at least two superconducting materials, a high J _C superconducting material and a low J _C superconducting material, which had to be manufactured separately. Therefore, there is a problem that it takes time to manufacture a sample.

For example, when two superconducting materials are produced by using one heat treatment furnace, it is necessary to spend about twice as long as the time for producing one superconducting material. Further, in order to appropriately satisfy the high floating characteristic and the high damping characteristic, it is complicated to manufacture the high J _C material and the low J _C material by post-processing and combining them. A superconducting material having a high floating characteristic and a high damping characteristic is desired in order to significantly shorten the sample preparation time and omit the post-processing. The present invention solves the above problems,
It is an object of the present invention to develop a superconducting material having high floating characteristics and high damping characteristics by a simple manufacturing method.

[0005]

In order to solve the above-mentioned problems, the present invention provides a superconducting material in which a portion having a high J _C and a portion having a low J _C are already integrated when they are manufactured, and the production thereof. Is the way. That is, single crystal REB
RE in the a ₂ Cu ₃ O _7-X phase (RE is a rare earth element containing Y or a combination thereof, hereinafter abbreviated as 123 phase)
_In a superconducting material in which a ₂ BaCuO ₅ phase (hereinafter abbreviated as 211 phase) is dispersed, the concentration of the 211 phase dispersed in 123 phase is 5 to 60% in terms of molar fraction, and the concentration of the 211 phase is molar. It is a superconducting material having a high floating characteristic and a high damping characteristic, which is characterized by comprising a portion B having a fraction of less than 5%. Here, the superconducting material having a high floating characteristic and a high damping characteristic is characterized in that the concentration of the 211 phase of the portion B is 0%, that is, only the 123 phase.

In addition, in a manufacturing method in which oxides of RE, Ba and Cu are mixed, molded, semi-melted, seeded, solidified and cooled, and heat-treated for oxygen enrichment, in the mixing / molding process, the composition of the 211 phase is a molar fraction. 5% and part A that becomes 5-60%
A superconducting material having a high floating characteristic and a high damping characteristic, characterized in that the 211 phase is finely dispersed with a concentration distribution in a single crystal 123 phase by molding into a molded body composed of a portion B which becomes less than It is a method of manufacturing a material. Here, the method is also characterized by being a method of manufacturing a superconducting material having a high floating characteristic and a high damping characteristic, in which the concentration of the 211 phase in the portion B is 0%, that is, only the 123 phase.

[0007]

The superconducting material called QMG material having a high J _C is characterized in that the 211 phase is dispersed in the 123 phase of a single crystal, and it is produced by the manufacturing process by the melting method. Here, the term "single crystal" is meant to include not only perfect single crystals but also those having defects such as small-angle grain boundaries that may be practically acceptable. Below, an example of the manufacturing process is shown.

(1) Weighing process: oxides of yttrium (Y), barium (Ba), and copper (Cu) are added to 123 phases and 2
The 11 phase stoichiometry is 1: 2: 3 ratio and 2: 1 :.
Weigh in a ratio between 1 and add to it the appropriate amount of platinum to refine the 211 phase. (2) Kneading process: The above mixed powder is kneaded for several hours in a mortar to make it sufficiently uniform. (3) Calcination process: The above kneaded powder is 800 to 900 in the atmosphere.
Calcination is performed at ℃ for several to several tens of hours. (4) Molding process: The calcined powder is crushed and molded into a predetermined shape by a uniaxial pressure molding machine. Use a hydrostatic press if necessary. (5) Firing process (solidification cooling process): The above-mentioned molded body is heated to 1000 ° C or higher in the atmosphere and kept at a constant temperature for several minutes to several hours, and then a seed crystal is installed if necessary, and the temperature is 1000 ° C.
Crystals are grown from the seed crystal by gradually cooling the front and rear at 200 ° C./hr or less. (6) Oxygen enrichment process: 600 ° C. of the fired body in an oxygen stream
Heat treatment is performed at ˜400 ° C. for several tens to several hundreds of hours to increase the amount of oxygen in the sample.

By the above processes (1) to (6),
Critical temperature is over 90K, J _C is 77K and 1T is 10
It is possible to produce a material having a density of more than 000 A / cm ² . From the stoichiometric composition of 123 phases in the weighing process of (1) above, 211
The reason for shifting to the phase side and weighing is as follows. QM
J _C of the G material changes as shown in FIG. 4 depending on the molar concentration of the 211 phase in the 123 phase. Since the 211st phase acts as a pinning point, too little _JC will decrease. On the other hand, since the 211 phase is a non-superconducting phase, the superconductivity of the entire sample decreases if too much. Therefore, in order to produce a high J _C superconducting material, the molar fraction of the 211 phase concentration in the single crystal 123 phase is preferably 5 to 60%. Furthermore, if the 211 phase is too much, the growth of the 123 phase, which is a superconducting phase, is hindered.
It can be said that 20 to 40% is particularly desirable as the phase molar concentration.

The present invention relates to a manufacturing method in which the manufacturing process of the above QMG material is improved, and a superconducting material manufactured by the manufacturing method. According to the method for producing a superconducting material of the present invention, in the molding process of the production process for the QMG material, the composition of the 211 phase is 5 to 60% in terms of mole fraction.
The method is characterized in that a molded body is formed from a portion A that becomes 5% and a portion B that becomes less than 5%. By imparting a concentration distribution to the composition of the molded body, the single crystal 123
A superconducting material characterized in that the 211 phase has a concentration distribution and is finely dispersed can be produced.

In the superconducting material of the present invention, the portion A where the charged composition of the 211 phase is 5 to 60% by mole fraction is high J.
_It has the characteristics of _C and bears the levitating function. On the other hand, the portion B in which the charged composition of the 211 phase is less than 5% in terms of mole fraction has a property of low J _C and plays a damping function. Therefore, the superconducting material of the present invention has high floating characteristics and high damping characteristics. In the superconducting material of the present invention, the portion having a high J _C and the portion having a low J _C are already integrated at the time of production, so that the sample production time can be significantly shortened.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 FIG. 1 shows an example of the superconducting material of the present invention. In Example 1, the 211 phase concentration was 3 in molar fraction.
A 0% portion A (reference numeral 1) and a 3% portion B (reference numeral 2) are superconducting materials having an upper and lower two-layer structure. The portion A having a 211 phase molar concentration of 30% has a high J _C characteristic and plays a levitating function. On the other hand, the part B where the 211 phase molar concentration is 3% has a low J _C
It has the characteristics of and has a damping function.

The method for producing the superconducting material of Example 1 will be described below. 211 As the raw material powder for the superconducting material of the part A having a molar concentration of 30%, the purity 9
9.9% yttrium (Y), barium (Ba), and copper (Cu) oxides were weighed in a ratio of 1.3: 1.7: 2.4, and 0.5% by weight of platinum was added thereto. . 2 of this weighing powder
After sufficiently kneading for a period of time, calcination was performed in the air at 900 ° C. for about 8 hours. On the other hand, as raw material powder of the superconducting material of the part B having a 211 phase molar concentration of 3%, the first commercially available oxide of yttrium (Y), barium (Ba), copper (Cu) having a purity of 99.9%. 1.03 for each:
Weigh in a ratio of 1.97: 2.94 and add 0.5% platinum to it.
Wt% was added. This weighed powder was sufficiently kneaded for 2 hours and then calcined in the air at 900 ° C. for about 8 hours.

Next, using a cylindrical mold, the calcined powder of the superconducting material of the part A having a 211 phase molar concentration of 30% is on the lower side, and the superconducting material of the part B having a 211 phase molar concentration of 3% is the lower part. Was formed so that the calcined powder of was on the upper side. This molded body was heated to 1100 ° C. in the air over 8 hours, held for 30 minutes, and then gradually cooled in the temperature region of 1005 to 980 ° C. over 100 hours to grow crystals. Finally, heat treatment was performed at 500 ° C. for about 150 hours in an oxygen atmosphere to add oxygen. The final size of the superconducting material of Example 1 is 46 mm in diameter and 20 mm in thickness (about 3 mm in the part B where the 211% molar concentration is 3%, and in part A where the 211% molar concentration is 30%).
Is about 17 mm).

In order to examine the effect of Example 1, the superconducting material of Example 1 and the 211 phase molar concentration were 3
Damping characteristics were measured and compared for a 0% ordinary QMG material (Comparative Example 1). Damping characteristics are measured by immersing the measurement sample in liquid nitrogen in a container,
With the Nd-Fe-B system permanent magnet of No. 2 kept at a flying height of 3 mm, the magnet-attached rod has 0.2 to 200 H.
It was measured and evaluated from the magnitude of the shake by applying the force of the frequency of z. The damping coefficient was calculated from the magnitude of the shake when a frequency force causing resonance was applied. When the damping coefficient is large, the shake becomes small.

As a result of the measurement, the damping coefficient of the superconducting material of Example 1 was 3.72 N · s / m, and the QM of Comparative Example 1 was
The damping coefficient of the G material was 1.21 N · s / m.
The reason why the damping characteristic is improved about three times by the method of the present invention is that the portion B having a 211 phase molar concentration of 3% is included. Based on QMG material with high floating characteristics,
By giving the 211 phase a concentration distribution, a superconducting material having high floating characteristics and high damping characteristics can be manufactured.

Next, the effect of shortening the sample preparation time will be described. In the production method of the present invention, the weighing process, the kneading process, and the calcination process need to be separate from each other, as compared with the conventional method of separately producing a high J _C superconducting material and a low J _C superconducting material. However, the ratio of the time required for these processes to the total sample preparation time is relatively small. In the production method of the present invention, it is possible to save the time and effort of performing the firing process (solidification cooling process) and the oxygen enrichment process that require a long time twice. Further, the time for processing and integrating the high J _C superconducting material and the low J _C superconducting material can be omitted. Therefore, the present invention has the effect of halving the sample preparation time compared to the prior art.

In this example, the 211 phase molar concentration was 30 in the molding process during the production of the superconducting material of the present invention.
% Part A of the superconducting material calcination powder is on the lower side and 211 phase molar concentration of 3% part B of the superconducting material calcination powder is on the upper side. It goes without saying that it has a great effect.

In this embodiment, 2 of the portion A having a levitating function is used.
The molar concentration of the 11th phase was 30%, which was 30%.
It is not limited to%. 211 phase 5 to 5
It goes without saying that the same effect can be obtained even if the amount is 60%. Further, in this embodiment, the molar concentration of the 211 phase of the portion B having the damping function was set to 3%, but this is 3%.
It is not limited to. Needless to say, the same effect can be obtained even if the molar concentration of the 211 phase is less than 5%.

Example 2 In Example 2, in FIG. 1, the portion A (reference numeral 1) where the concentration of the 211 phase is 40% and the portion B (reference numeral 2) are 0% in terms of mole fraction.
(That is, the portion having only 123 phases) is a superconducting material having a two-layered structure. The portion A having a 211 phase molar concentration of 40% has a high J _C characteristic and plays a levitating function. on the other hand,
The part B, which is the 123 phase, has the characteristic of low J _C and has a damping function.

The method for producing the superconducting material of Example 2 will be described below. In the weighing process, the manufacturing method of Example 2
211 Yttrium (Y), barium (Ba), and copper (Cu) oxides are weighed in a ratio of 1.4: 1.6: 2.2 as raw material powder of the superconducting material of the part A having a molar concentration of 40% of 40%. In addition, yttrium (Y), barium (Ba), copper (C
The manufacturing process of Example 1 is the same, except that the oxides of u) are weighed in a ratio of 1: 2: 3, respectively.

In order to examine the effect of Example 2, the superconducting material of Example 2 and the 211 phase molar concentration were 4
The damping characteristics of a normal QMG material (Comparative Example 2) of 0% were measured and compared. As a result of the measurement, the damping coefficient of the superconducting material of Example 2 is 4.21 N · s / m.
Then, the damping coefficient of the QMG material of Comparative Example 2 is 1.04N.
-It was s / m. The reason why the damping characteristic is improved about three times or more by the method of the present invention is that the portion B which is 123 phase is included. A superconducting material having a high floating characteristic and a high damping characteristic can be manufactured by providing a concentration distribution in the 211 phase based on a QMG material having a high floating characteristic. Further, like the first embodiment, the present invention has an effect of halving the sample preparation time as compared with the conventional technique.

Example 3 FIG. 3 shows another example of the superconducting material of the present invention. In Example 3, the portion A (reference numeral 3) and the portion B (reference numeral 4) in which the concentration of the 211 phase was 30% in terms of molar fraction were 0%.
The superconducting material (that is, the portion having only 123 phases) has a concentric circular structure. The portion A having a 211 phase molar concentration of 30% has a high J _C characteristic and plays a levitating function. on the other hand,
The part B, which is only the 123 phase, has the characteristic of low J _C and has a damping function.

The method for producing the superconducting material of Example 3 will be described below. The manufacturing method of Example 3 was
Yttrium (Y), barium (Ba), copper (C) as raw material powder of the superconducting material of the portion A having 11-phase molar concentration of 30%
the oxide of u) is weighed in a ratio of 1.3: 1.7: 2.4,
Further, yttrium (Y), barium (Ba), copper (Cu) as raw material powder of the superconducting material of the part B which is 123 phase
Oxides were weighed in a ratio of 1: 2: 3, respectively, and in the molding process, a portion A having a 211 phase molar concentration of 30% was formed into an outer shape and a 123 phase portion B was formed into an inner shape. The manufacturing process is the same as that of the embodiment 1 except for the above. The final size of the superconducting material of Example 3 is
The diameter of the portion A having a 211 phase molar concentration of 30% is 46 mm,
The diameter of the part B, which is 123 phase, is 22 mm and the thickness is 20 m.
m.

In order to investigate the effect of the third embodiment, the superconducting material of the third embodiment and the 211 phase molar concentration were 3 over the entire sample.
Damping characteristics were measured and compared for a 0% ordinary QMG material (Comparative Example 1). , Measurement results, Example 3
Damping coefficient of superconducting material of 4.77N · s / m
Then, the damping coefficient of the QMG material of Comparative Example 1 is 1.21N.
-It was s / m. The reason why the damping characteristic is improved about three times or more by the method of the present invention is that the portion B which is 123 phase is included. A superconducting material having high floating characteristics and high damping characteristics can be produced by providing a concentration distribution in the 211 phase based on a QMG material having high floating characteristics. Further, the present invention has an effect of halving the sample preparation time as compared with the conventional technique as in the first embodiment. In particular, when the material is processed into a cylindrical shape as in this embodiment, the oxide superconducting material is a ceramic having processing difficulty, so that the effect of shortening the sample preparation time is great.

[0026]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the superconducting material is characterized in that the 211 phase finely dispersed in the single crystal 123 phase has a concentration distribution so as to have high floating characteristics and high damping characteristics. And a method for manufacturing the same. 211 The portion with a high molar concentration has a high J _C characteristic and plays a levitating function. 211 The portion with a low molar concentration has a low J _C characteristic and plays a damping function. By using the superconducting material and the manufacturing process of the present invention, it is possible to realize a significant reduction in sample preparation time as compared with the prior art. Therefore, the present invention enables the practical application of the superconducting levitation device in a wide range of technical fields.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a superconducting material of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a superconducting material of the present invention.

FIG. 3 is a graph showing the relationship between the critical current density and the 211 phase molar concentration in the QMG material.

Claims (4)

[Claims] 1. A RE ₂ BaCuO ₅ phase (hereinafter abbreviated as 211 phase) in a single crystal REBa ₂ Cu ₃ O _7-X phase (RE is a rare earth element containing Y or a combination thereof, hereinafter abbreviated as 123 phase). ) Are dispersed in the superconducting material, the portion A in which the concentration of the 211 phase dispersed in the 123 phase is 5 to 60% by mole fraction, and the portion B in which the concentration of the 211 phase is less than 5% by mole fraction. A superconducting material having a high levitation characteristic and a high damping characteristic. 2. The superconducting material having high floating characteristics and high damping characteristics according to claim 1, wherein the concentration of the 211 phase of the portion B is 0%, that is, only the 123 phase. 3. A manufacturing method in which oxides of RE, Ba, and Cu are mixed, molded, semi-melted, seeded, solidified and cooled, and oxygen-enriched heat-treated, and RE ₂ Ba is mixed and molded during the manufacturing process.
A molded product comprising a portion A in which the charged composition of the CuO ₅ phase (RE is a rare earth element containing Y or a combination thereof, abbreviated as 211 phase hereinafter) is 5 to 60% in mole fraction and a portion B in which it is less than 5%. By molding into a single crystal R
A method for producing a superconducting material having high floating characteristics and high damping characteristics, which comprises finely dispersing 211 phases in an EBa ₂ Cu ₃ O _7-X phase with a concentration distribution. 4. The method for producing a superconducting material having high floating characteristics and high damping characteristics according to claim 3, wherein the concentration of the 211 phase of the portion B is 0%, that is, only the 123 phase.