JPH03500831A - Weak link superconductor loop device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Weak link superconductor loop device The present invention is a weak link superconductor loop device. -1ink　) superconductor loop device with characteristics and this loop device Regarding the manufacturing method.

Already proposed weak-link superconductor loop devices have internally discrete It is formed from loops of superconducting material with weak links. Traditionally this is , to provide weak links in the form of point contact, compression, or dielectric bonding. , and these loops showed good supercurrent and magnetic flux properties.

However, point-contact weak links obtain and maintain the desired properties of the loop. On the other hand, compression and insulation bonding weak relief Links require relatively complex molding techniques and are expensive to manufacture.

Y-Ba-Cu-0-based high-temperature ceramic metal oxide superconductor material is ical Review Letters, volume 58J 908- It is proposed on page 911.

According to the invention, a superconductor comprising a body formed of a substantially non-superconducting matrix A body loop device is provided, which incorporates the unique structure of weak link superconducting loops. Regions of superconducting material are provided dispersed within the body to impart properties to the body.

The present invention eliminates discrete weak links as required in previously proposed loops. The matrix is non-superconducting and allows the magnetic flux to pass through the loop without the need to provide a separate The material from which the loop is formed has the characteristics of a superconducting weak link loop. It has the advantage that it has the inherent property of giving a loop .

Preferably, the loop is molded from a ceramic material, but in other embodiments: in a non-superconductor matrix, such as PbSNb or Ti in an epoxy resin matrix. Dispersed superconductors can also be used.

The above matrix has low conductivity so that the device can be used at high frequencies. It is particularly desirable to have. The conductivity range of the matrix is from 1mΩ・cm to 108Ω・ It would be cm.

The criteria for “superconductivity”, “superconductivity”, “non-superconductivity” and “low conductivity” are related to the characteristics at the intended operating temperature.

The present invention provides a weak link loop that is easily remanufacturable. Furthermore, cerami The use of bulk material allows the loop to be manufactured using conventional powder techniques, Therefore, it can be manufactured economically and utilizes materials with a relatively high superconducting transition temperature. Provides a loop that can be used.

When a ceramic material is used in the present invention, it is partitioned into a bulk non-superconducting phase. It can contain small regions of dispersed superconducting phase, and the superconducting regions are weakly associated.

However, it is also possible, and desirable, for a superconducting phase to be present as the main part of the material. There are cases where it is true. Therefore, the superconducting phase and the substantially non-superconducting phase are in any mutual ratio. It is also possible that it exists.

Preferably, the ceramic material is of the Y-Ba-Cu-0 series, For example, La-Ba-Cu-0 system or La- or Sc-based ceramic metal oxide superconductor such as La-3r-Cu-0 system conductor or other suitable material from the rare earth-barium/strontium-Cu-O system other ceramics or materials with high superconducting transition temperatures, such as ceramic materials is also available.

A particularly desirable material is (Yl-X Bx)2Cu04-a (where d Ta. However, it has now been confirmed that this makes up a larger portion of the material.

by changing the chemical composition, microstructure, dispersion and properties of the ceramic material phase. It is possible to change the weak link characteristics of loops formed from the above materials. It is possible. The phase composition of the above materials can be determined by mechanical grinding, chemical deposition, base It can be changed by process parameters such as paper transfer, temperature, atmosphere, pressure, and sintering. can be done.゛The superconducting material may be present in any proportion of the body. Both are possible.

The above superconducting loop device consists of a ceramic superconductor dispersed within a non-superconducting matrix as described above. It can be formed from multiphase materials that include a conducting phase, and non-superconducting matrix (rate) ceramic material or polymer resin. this is It is also possible to form agglomerated bodies of granular multiphase materials without the use of binders. . However, the service life of the body depends on the use of a binder or external casing. It can be further improved. Alternatively, the materials described above may contain non-superconducting matrix, especially (e.g. about 10 Granular ceramic superconductor bonded within a polymer resin binder (in an amount of % by weight) (For example, YB a2 Cu307-a).

The above types of materials have superconducting weak link loop properties within the bulk of the material. A loop can be formed. Therefore, the above body may be a loop or any other It can also be formed into a loop shape. This material exhibits weak link-loop behavior The unique properties of this material allow it to be used in high frequency or direct current 5QUID (superconducting quantum interferometers). ).

In one example, a granular multiphase material consisting of particles having both superconducting and non-superconducting phases is used. However, in order to obtain the desired superconducting properties, which are influenced by the degree of contact between particles, at least 7 A degree of compression of 0% would be required.

The superconducting properties of granular materials are influenced by the contact surfaces of the particles of superconducting material. super legend Improvements in conductive properties can be achieved by improving the contact surfaces of particles.

Loop devices can also be manufactured using thick film technology.

Accordingly, in another aspect of the invention, a suitable material is deposited on a substrate, and the deposited material is processing the material to define a loop of material having the above structure and properties. , a method of manufacturing a weak link superconducting loop device is provided.

The weak link characteristics of loops formed in accordance with the present invention, e.g. processing, placing the loop in a uniform magnetic field, passing a current through the loop, providing a coil around the loop and passing a current around said coil. subjecting the loop to electrochemical processes; and Adjustment is possible by other techniques such as global heating/cooling. , The weak link property of the loop according to the present invention allows superconducting quantum interferometer (SQU) The above route is used in devices that rely on sensing changes in magnetic fields as a function, such as It becomes possible to incorporate

The superconducting properties of the loops are influenced by the density and microstructure of the superconducting material.

This, on the other hand, is influenced by particle size, amount of binder used, degree of sintering, etc. le If powder techniques are used to form the loop or body, the density will also vary before sintering. or by the pressure used to compress the material during sintering.

Embodiments of the invention will now be described in the following examples.

Example 1 The loop is a circular ring with an outer diameter of 10 mm, an inner diameter of 5 mm, and a thickness of 3 mm. It will be. The above ring is Yl, 2 Bo, 8 Cu 04-a (d is arbitrary here) This consists of 5.4495g of Y2O3, 13,3512g of BaC0, and and 3.1995g of CuO (all Analar Laboratory reagent) were added to the bottle. It is prepared by mixing for 3 minutes in a mill type mixer. This mixture is Provide accurate proportions of metal elements. The above powder mixture was heated in an air atmosphere for 45 minutes. Heated in an alumina crucible in a 950°C furnace and stirred 20 minutes after heating started. . The above materials are taken out of the furnace and crushed by a mill and mortar to a powder with the density of fine powder. is formed. The crushed material is heated in the above oven for a further 40 minutes until heating starts at 20 minutes. Stir after minutes. The above material is taken out from the furnace and after cooling, 1.5g of the above material is It is compression molded into a ring using a machine at about 9000 lb. The ring is made by AI It is sintered at 950° C. for 16 hours in an air atmosphere in a pot.

Figures 1 and 2 show the X-ray diffraction spectra of materials similar to those described above. As shown , X-ray analysis shows the presence of several phases. Figure 2 is one of the spectra in Figure 1. FIG.

In FIG. 2, region A is due to the presence of a superconducting phase. Loop formed from the above material is the magnetic flux in the loop, and the discrete quantity of flux quanta is φ. Quantified as = h / 2 e It will be done. This is a normal superconducting flux converter and a normal high frequency 5QUID (S.A. Czech Corporation Limited). This is 1 Corresponds to the limiting current around the loop of mA. These measurements were observed at 4.2K. 90 and other superconducting behavior is observed in similar samples. .

When used as a high frequency 5QUID, the characteristic 5QUID behavior is better than 4.2. observed at higher temperatures.

Example 2 A body with non-loop shape and weak link body behavior is formed as follows. Ru.

A 1 mm cube of compressed multiphase ceramic material (Y 1.2 B (1 , B Cu O4-+) was wound 10 times over a length of 6 mm and a diameter of 3 mm. placed inside the coil. The above coil is in parallel with a 350pF capacitor. connected, demonstrating simple high frequency 5QUID behavior at liquid nitrogen temperature. Above configuration is a suitable electronic device (e.g. rNature, 328.P, 47.1978 J) detects changes in the ambient magnetic field on the order of 1 nT. It can be used for. The performance of devices such as those described above will depend on whether they are affected by the surrounding magnetic field. It can be used as a very sensitive magnetic meter for the position of objects. It can be adjusted to a certain degree.

Example 3 Superconducting loops can be formed using the thick film technology described below.

■The above ceramic multiphase material has a composition of 1 Yl, 2 B'0.8 Cu 04-a. Formed as described in Example 1 and finely powdered to a particle size of approximately 10-30 μm. It will be done. This material is thoroughly mixed with an organic binder such as polyvinyl alcohol. Ru.

2. The powdered ceramic and binder are a thin mixture of the ceramic and binder. The surface of a 1 mm cylindrical rod made of zirconia was coated by immersing it in the compound. arranged to overturn. The thickness of the above coating is 10-100 μm after firing. selected to give.

3. The above mixture is dried to allow partial evaporation of the PVA.

4. The coated rod was heated at 950°C for 12 hours in an air or oxygen atmosphere. Baked for an hour.

5. The fired rod was heated in an air or oxygen atmosphere for about 12 hours. and slowly cools down.

6. The above rod is then heated to 350-450°C and heated in an oxygen atmosphere. The temperature is maintained for 6 hours and then cooled.

7. The above coated cylinder was cut into 1 mm thick disks and given a unique weak A loop of material having link superconducting properties is provided.

Seed inheritance Example 3 is repeated using YBa2Cu30t-y as starting material. It will be done. The above materials are superconductors. However, the final Thick films include multiple phases and provide the desired weak link properties.

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Claims (18)

[Claims] 1. Weak link The internal structure is designed to give the body the unique properties of a superconducting loop. formed from a substantially non-superconducting matrix with regions of superconducting material dispersed in the A superconductor loop device characterized by having a body that is 2. The device of claim 1, wherein the superconducting material is a ceramic superconductor. 3. Claim 1 or 2, wherein the substantially non-superconducting matrix is a ceramic material. Devices listed. 4. A non-superconducting phase that provides the above-mentioned matrix and a dispersed superconductor that provides the above-mentioned superconducting material region. 2. The device of claim 1 formed from a multiphase material comprising a conductive phase. 5. 5. The device of claim 4, wherein the multiphase material is a ceramic material. 6. The above superconducting material is selected from the rare earth-barium/sotrontium-Cu-O system. The device according to any one of claims 1 to 5, which is a selected superconducting ceramic material. Vice. 7. Claim 1 or 2, wherein said substantially non-superconducting matrix is provided from a resin. device. 8. A device according to any one of claims 1 to 6, wherein the body is a sintered body. chair. 9. Any one of claims 1 to 6, wherein the body comprises unsintered and compressed particles. or the device according to item 1. 10. Claim 1, wherein the body is formed by thick film technology on a substrate. 7. The device according to any one of 6 to 6. 11. The device according to any one of claims 1 to 10, wherein the matrix has low conductivity. Vice. 12. A method for manufacturing a superconductor loop device according to claim 1, comprising: Comprising a process of forming a body from particles of a material having a superconducting phase and a dispersed superconducting phase how to. 13. 13. The method of claim 12, wherein the body is compression molded. 14. 13. The method of claim 12, wherein the body is formed by compaction and sintering. 15. Claim 1, wherein the body is formed by thick film technology on a substrate. The method described in 2. 16. The body mixes the particles with a binder and applies the mixture onto the substrate. formed by a process comprising forming the coated substrate as a coating and firing the coated substrate. 16. The method according to claim 15. 17. weak link superconducting loops to give the body the unique properties of superconducting loops. formed from mutually disposed regions of superconducting material and regions of substantially non-superconducting material. A superconductor loop device consisting of a closed body. 18. 18. A method for manufacturing a superconductor loop device according to claim 17, comprising: In addition to mixing particles consisting of or containing a superconductor with a binder , forming the mixture to form a body.