JPH0776155B2 - Method for manufacturing ceramic superconducting compact - Google Patents

Description

The present invention relates to a method for producing a ceramics superconducting compact having a high critical current density.

[Conventional technology and its problems]

When a non-superconducting substance is contained in or coated on the superconducting compact, a so-called pinning effect that prevents the movement of magnetic flux occurs and the critical current density (hereinafter abbreviated as J _c ) is improved.

Conventionally, a method of internally containing or coating a non-superconducting substance in a ceramic superconducting molded body is to mix a plurality of raw material powders which react by heat treatment to form a superconductor at a predetermined molar ratio and knead them with water or the like, and then heat this. Processed into a superconductor,
Then, a step of depositing a non-superconducting substance on the resultant and baking the same is repeated by a desired number of times.

By the way, since the pinning effect of a non-superconducting substance is proportional to its surface area, it is effective to distribute the non-superconducting substance in a thin layer, but it is difficult to form the non-superconducting substance thin according to the above conventional method. Therefore, not only the pinning efficiency is poor, but the volume ratio occupied by the superconductor is reduced. Furthermore, since the powder particle size of the raw material is large in the conventional superconductor, the solid-phase reaction between the powder particles forming the superconductor However, there was a drawback that the characteristics such as Jc were low because of insufficient characteristics.

[Means for solving problems]

The present invention has been made in view of the above circumstances, and its object is to provide a method for manufacturing a ceramics superconducting molded body in which a non-superconducting substance is thinly contained or coated. That is, the present invention uses a plurality of targets made of a compound containing each atom constituting a superconductor and a target of a non-superconducting substance to form an atom constituting a superconductor and a non-superconducting substance on a substrate by a vapor phase growth method. And a desired thickness is alternately laminated.

In the present invention, Y-Ba-Cu-O system, Y-Sr-Cu-O system, La-S
alkaline earth metals such as r-Cu-O system, rare earth elements, copper,
It is highly adaptable to ceramic superconductors made of oxygen, and the above constituent elements have a perovskite type structure in which each atom is sequentially arranged in the order of Y Cu Ba Cu Ba Cu Y when the Y-Ba-Cu-O system is exemplified. As a result, it can become a superconductor.

As a target compound, for example, Y ₂ O ₃ , BaCO ₃ , CuO ₃ or the like is used in the Y-Ba-Cu-O system.

In addition, Cu, Cu-Ni, W, Mo, Ni, Al, Sb-Pb are used for non-superconducting materials.
Metal materials such as or glass, Al ₂ O ₃ ,, Y ₂ O ₃ ,, CuO, CaO, MgO,
An inorganic material such as ZnO ₂ is used.

As the vapor phase growth method, a PVD method such as a sputtering method, an ion plating method, a plasma polymerization method, or a vacuum deposition method is used.

CVD methods such as thermal decomposition method, reduction method and reaction method can also be applied, but it is not practical because the vapor pressure of the raw material is low and introduction into the reaction system in the gas phase is difficult.

[Action]

In the method of the present invention, since the atomic units are stacked by the vapor phase growth method, a perovskite structure which can be a superconductor can be easily formed. Further, according to the vapor phase growth method, the non-superconducting substance can be extremely thinly laminated on the superconducting compact.

The non-superconducting substance is contained in or coated on the superconducting molded body to cause a pinning effect, but in addition to this, it has the function of enhancing the magnetic properties of the superconductor and further improving the mechanical properties.

〔Example〕

 The present invention will be specifically described below with reference to examples.

(Example 1) Compound Y containing constituent atoms of a Y-Ba-Cu-O-based superconductor
₂ O ₃ , BaO, CuO powder and non-superconducting ZrO ₂ powder were pressed into a disk with a diameter of 50 mm and a thickness of 3 mm.
The individual compacts were set in different target holders of a high-frequency sputtering apparatus, sputtering was performed in a mixed gas of argon and oxygen, and constituent atoms of a superconductor and non-superconducting substances were alternately laminated on a SUS304 wire having a diameter of 50 μm.

First, Y ₂ O ₃ , BaO, and CuO were sputtered so that the molar ratio of Y: Ba: Cu was 1: 2: 3 to form a film of about 1 μm on the above line, and then ZrO ₂ was formed on this film. Was sputtered for 20Å and this process was repeated 10 times to form a superconductor film having a thickness of about 10 μm.

For comparison, a sample line was prepared by the following conventional method.

(Comparative Example 1) Y ₂ O ₃ , BaO, and CuO were kneaded with water so that the molar ratio of Y: Ba: Cu was 1: 2: 3, and 3.5 μm of this was adhered onto a SUS304 wire of 50 μmφ. Baking at 400 ° C. for 2 hours, and then ZrO ₂ was spray-dried thereon to a thickness of about 1 μm. The series of steps described above was repeated three times to form a superconductor film having a thickness of about 10 μm, and this was heat treated at 900 ° C. for 4H.

In order to adjust the chemical composition and crystal structure of two samples lines of Examples and Comparative Examples, 700 ° C. in O ₂ gas stream 8
After heating to H, it was gradually cooled at a rate of 2 ° C / min.

The T _c , J _c and magnetic susceptibility of these sample lines were measured.
The results are shown in Table 1.

As is clear from Table 1, the product (1) of the present invention has higher values of T _c , J _c and magnetic susceptibility than the product of the conventional comparison method (2).

In the examples, the non-superconducting substance is distributed in concentric layers, but the same effect can be obtained by dispersing the non-superconducting substance in the form of thin pieces.

〔effect〕

As described above, according to the present invention, since the non-superconducting substance can be thinly contained or coated in the superconductor, pinning is efficiently performed, and the ratio of the superconductor is high, and the constituent atoms of the superconductor are appropriately arranged. Therefore, a ceramics superconducting compact having excellent superconducting properties such as J _c can be obtained.
It has a remarkable industrial effect.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display area H01B 13/00 HCU 7244-5G

Claims (3)

[Claims] 1. A plurality of targets made of a compound containing each atom constituting a superconductor and a target of a non-superconducting substance are used to deposit the atoms constituting the superconductor and the non-superconducting substance on a substrate by a vapor phase growth method. A method for manufacturing a ceramics superconducting molded body, comprising alternately laminating a desired thickness. 2. The method for producing a ceramics superconducting compact according to claim 1, wherein the atoms constituting the superconductor are composed of an alkaline earth metal, a rare earth element, copper and oxygen. 3. The method for producing a ceramics superconducting compact according to claim 1, wherein the vapor phase growth method is a PVD method.