JPH042603A - Formation of superconductive film - Google Patents

Abstract

PURPOSE:To extremely readily obtain a thick superconductor film by blending the composition power of the superconductor with a binder, coating the blended product on a substrated, sintering the formed coating film as the precursor of the superconductive film by irradiation of laser beams and subsequently gradually cooling the sintered film. CONSTITUTION:The composition powder of a superconductor prepared so as to give the composition ratio of the superconductor is blended and kneaded with binder and subsequently coated on a substrate 2 to form a coating film 3. The coating film is irradiated with laser beams 4 to heat the coating film 3 at a temperature lower than the melting point of the composition powder for sintering the coating film. The coating film is gradually cooled with the sufficient absorption of oxygen in the coating film (the gradual cooling may be performed in the atmosphere but the feed of oxygen 10 from an oxygen- blowing device 9 permits to accelerate the oxygen absorption of the coating film).

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing a superconducting film.

[Prior Art] It has been known that when metals and alloys such as mercury, soot, and lead are cooled below their respective critical temperatures, their electrical resistance disappears, that is, they become superconducting.

Recently, however, it has been discovered that not only metals and alloys, but also oxide ceramics exhibit superconductivity.

Ceramics that exhibit the above-mentioned superconductivity are currently made of yttrium-based superconductors made of yttrium, barium, and copper in a composition ratio of 1:2:3, and bismuth-strontium, calcium, and copper made in a composition ratio of 2:2:2:3. The bismuth-based superconductors that we made, thallium, barium, calcium, and copper, are 2:
Thallium-based superconductors made with a composition ratio of 2:2:3 are known, and in contrast to the critical temperature of conventional metals and alloys, which are in the extremely low region close to the absolute temperature, these superconductors have a relative As it has a high critical temperature and exhibits superconductivity even at the temperature of inexpensive liquid nitrogen (-196 degrees Celsius), we are researching ceramics that exhibit superconductivity for practical use in MHD power generation, linear motor cars, etc. is becoming popular.

To produce such a ceramic exhibiting superconductivity (hereinafter referred to as a superconductor), the superconductor raw material is melted and evaporated in an evacuated chamber, and fine particles of the composition of the raw material are placed on opposing substrates. The PVD method (physical vapor deposition method) in which a superconducting film is formed by depositing a CVD for forming a superconducting film on a substrate provided in the chamber by a gas phase chemical reaction (thermal decomposition, hydrogen reduction, oxidation, substitution reaction, etc.)
(chemical vapor deposition method), etc. are used.

[Problem to be solved by the invention] However, there is a problem in that it is difficult to produce a thick superconducting film using the PVD method or CVD method.
Another disadvantage is that a superconducting film cannot be produced unless large-scale equipment such as a chamber for vapor deposition is prepared.

Therefore, in the PVD method and CVD method, since the film thickness is very thin, there are problems in handling from an industrial point of view, as even the slightest scratch can impair superconductivity.

Furthermore, it is difficult to produce a superconducting film with a large area or a complicated shape using the PVD method or CVD method.

The present invention was developed in view of the above-mentioned circumstances, and it is possible to extremely easily produce a thick superconducting film in the atmosphere without requiring any equipment such as a chamber for vapor deposition, and in addition, over a large area. The purpose of the present invention is to provide a method for producing a superconducting film that can also produce superconducting films with complex shapes.

[Means for Solving the Problems] The present invention involves forming a film on a substrate by applying a composition powder of a superconductor prepared to have the composition ratio of the superconductor with a binder to the substrate, and forming a film on the substrate. The superconductor is characterized in that the film is sintered by irradiating it with a laser beam and heating at a temperature lower than the melting point of the composition powder for a required period of time, and then slowly cooling while causing the film to absorb sufficient oxygen. This relates to a method for producing a film.

[Function] Therefore, in the present invention, a composition powder mixed with a binder is applied to a substrate to form a film that becomes a precursor of a superconducting film, and this film is sintered by a laser beam, and then slowly cooled. A superconducting film is thereby produced on the substrate.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention.

Yttrium-based, bismuth-based, which exhibits superconductivity as mentioned above,
A composition powder l prepared to have a composition ratio of a thallium-based superconductor or the like is mixed with a binder such as an organic solvent that easily evaporates during sintering and applied to the upper surface of the substrate 2. A coating 3 of the composition powder 1 dissolved with the binder is formed on the substrate (see FIG. 1).

For example, when it is desired to produce an yttrium-based superconducting film, a composition powder prepared such that the composition ratio of yttrium/barium φ copper is 1:2:3 is mixed into a binder and then deposited on the substrate.
Apply to the top surface.

It goes without saying that the binder should be selected to be one that does not chemically react with the composition powder 1.

Next, as shown in FIG. 2, a laser beam 4 guided from a well-known laser device through a lens system is irradiated onto the upper surface of the substrate 2 through a focusing lens 5, a fixed mirror 6, and a swinging mirror 7. Then, the coating 3 is sintered. In the figure, 4a indicates a focal point.

At this time, the oscillating mirror 7 is oscillated as shown by arrow A in FIG. 2, and the laser irradiation position on the coating 3 is constantly changed, so that the surface of the coating 3 is evenly heated.

Further, the sintering temperature of the coating 3 is set to a temperature lower than the melting point of the composition powder 1 forming the coating 3, and the sintering of the coating 3 is completed without melting the composition powder 1 of the coating 3. It is held for a predetermined period of time.

For example, in the case of yttrium, the sintering temperature is maintained at about 950° C. for about 2 hours.

Note that the binder evaporates during the sintering.

In addition, as shown in Fig. 3, for a large-area coating 3, the laser beam 4 side is gradually moved horizontally (in the direction of arrow B in the figure).
The entire large-area coating 3 is sintered by sequentially performing partial sintering by moving the substrate 2 side in a horizontal direction (in the direction of arrow C in the figure). All you have to do is do it.

Furthermore, the coating 3 sintered on the upper surface of the substrate 2 as described above is
The output of the laser beam 4 irradiated to the coating 3 is gradually reduced, or the irradiation of the laser beam 4 is stopped and the heating temperature is gradually lowered using an auxiliary heat source (not shown) such as a heater. By doing so, the film 3 is slowly cooled down over time while sufficiently absorbing oxygen, and a superconducting film 8 is formed on the upper surface of the substrate 2 (see FIG. 4).

At this time, the film 3 may be slowly cooled in the atmosphere, but if the surroundings of the film 3 are made into an oxygen-added atmosphere by supplying oxygen lO from the oxygen supply device 9, the film 3 can be slowly cooled. Oxygen absorption of No. 3 can be promoted, and superconductivity becomes good.

Therefore, according to the above, a thick superconducting film can be extremely easily produced in the atmosphere without requiring equipment such as a chamber for vapor deposition.

Further, in the method for producing a superconducting film of the present invention, a composition powder l of a superconductor is dissolved with a binder and applied to a substrate 2, thereby forming a coating 3, which is a precursor of a superconducting film, without any restrictions on its area or shape. Moreover, since this coating 3 can be easily sintered by irradiation with the laser beam 4, a superconducting film 8 having a large area and a complicated shape can be obtained.

Furthermore, since the laser beam 4 can be easily guided to the position where the coating 3 is formed on the substrate 2 via a mirror or the like, there is no need to carry the substrate 3 to a heating furnace or the like for sintering. The properties are extremely good.

It should be noted that the method for producing a superconducting film of the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] As explained above, according to the method for producing a superconducting film of the present invention, various excellent effects as described below can be achieved.

(D) A thick superconducting film can be produced extremely easily in the atmosphere without requiring equipment such as a chamber for vapor deposition.

<n> Since a superconducting film can be produced without any restrictions on its area or shape, a superconducting film with a large area or a complicated shape can be obtained.

[Phase] Since the coating can be sintered at the position where the coating is formed on the substrate, the workability is extremely good.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a state in which a film is formed on a substrate in an embodiment of the present invention, Fig. 2 is a schematic diagram showing an example of sintering the film by irradiating a laser beam, and Fig. 3 is a diagram showing a large area. FIG. 4 is a schematic diagram showing an example of sintering a film of the present invention, and FIG. 4 is a diagram showing a state in which a superconducting film is produced. In the figure, 1 is a composition powder, 2 is a substrate, 3 is a coating, 4 is a laser beam, 8 is a superconducting film, and 10 is oxygen.

Claims (1)

[Claims] 1) A superconductor composition powder prepared to have the composition ratio of the superconductor is mixed with a binder and applied to a substrate to form a film on the substrate, and a laser beam is irradiated onto the film to remove the composition powder. A method for producing a superconducting film, comprising sintering the film by heating at a temperature lower than the melting point of the film for a required period of time, and then slowly cooling the film while allowing the film to absorb sufficient oxygen.