JPH01198465A - Superconducting coated material - Google Patents

Abstract

PURPOSE:To improve the water and acid resistances of a superconducting material by coating a substrate with a superconductor contg. Y or lanthanoid and the surface of the superconductor with the fluoride of Y or lanthanoid. CONSTITUTION:A thin film 12 of a superconductor contg. at least one kind of primary element selected among Y and lanthanoids, e.g., Y-Ba-Cu-O is formed on a substrate 11 of sapphire, etc., by high frequency magnetron sputtering or other method. A coating layer 13 of the fluoride of at least one kind of secondary element selected among Y and lanthanoids, e.g., YF3 is then formed on the surface of the thin film 12 by plasma CVD or other method. The resulting superconducting coated material does not dissolve in water and acids, so it can be subjected to desired processing without damaging the superconductor.

Description

[Detailed Description of the Invention] (Summary) The present invention relates to a superconducting composite material comprising a superconductor containing at least one element selected from the group consisting of inotrium and lanthanoids. , water resistance, which prevents the dissolution of superconductors in water and acids, allowing various processing to be performed without damage;
The purpose of the present invention is to provide a superconducting material with excellent acid resistance, including a superconductor containing at least one first element selected from the group consisting of yttrium and lanthanoids, and a surface of the superconductor. and a coating layer of a fluoride of at least one second element selected from the group consisting of yttrium and lanthanide.

[Industrial application field]

The present invention relates to a superconducting composite material comprising a superconductor containing at least one element selected from the group consisting of indolium and lanthanides.

Examples of such superconductors include Y-Ba-C
u -0, La-Ba-Cu -0, La-5r-Cu
Oxide-based ceramics consisting of an element of group 111B (or lanthanide element) of the periodic table, an element of group 11A, such as Cu-0, have recently been developed. These superconductors have a high critical temperature of about 90°C or higher, whereas previously known metal superconductors had a critical temperature of at most about 20°C, so they are used as superconducting magnets, The possibility of putting superconductors into practical use as superconducting wiring, 5QUID magnetometers, etc. has increased dramatically.

[Conventional technology]

In order to put superconductors into practical use for the above and other uses, it is necessary to subject them to various processing, either singly or when incorporated as a component.

In particular, processing in which elements containing superconductors and the like are treated with water and acids such as nitric acid, hydrochloric acid, and hydrofluoric acid for cleaning and the like is frequently performed. In many cases, superconductors such as those mentioned above are easily dissolved in both water and the acids mentioned above, so they are severely damaged during the processing process, and their excellent superconducting properties are lost or the superconductors are There is an extremely high risk that the entire conductor will melt away.

[Problem to be solved by the invention]

The fact that superconductors easily dissolve in water and the above-mentioned acids is an inherent property based on the composition and structure of superconductors. On the other hand, the composition and structure of superconductors are in the optimal range where the best superconductivity 4 properties can be obtained, and this range is extremely narrow, so it is difficult to adjust the composition and structure to improve water resistance and acid resistance. Practically impossible. Therefore, there is a problem in that it is extremely difficult to carry out necessary processing depending on the application, and the practical application of superconductors is hindered.

Therefore, an object of the present invention is to provide a superconducting material with excellent water and acid resistance that can be subjected to various processing without damage by preventing the superconductor from dissolving in water and acid. .

[Means to solve the problem]

The above object is to provide a superconductor containing at least one first element selected from the group consisting of yttrium and lanthanoids, and a superconductor containing yttrium and lanthanides covered on the surface of the superconductor. This is achieved by a superconducting composite material comprising a coating layer of at least one second element fluoride selected from the group consisting of:

In the superconducting composite material of the present invention, the first element contained in the superconductor and the second element forming the fluoride of the coating layer are not necessarily the same element, It is sufficient that each element is a small amount (both of which are one type of element) selected from the group consisting of yttrium and lanthanoids.

It is advantageous for the first element and the second element to be the same element. If these elements are the same, even if thermal diffusion or reaction occurs at the interface between the superconductor and the coating layer, compositional fluctuations in the region near the interface will be suppressed to a minimum. In addition, since the same or similar material as the raw material of the superconductor can be used as the raw material for forming the coating layer, the types of raw materials to be prepared can be minimized. can be formed in the same or similar manner as superconductors.

Y in which the superconductor contains yttrium as the first element
BazCu30y-x (OS
Most advantageously, it is formed of Here, the smaller X is (the closer 7-x is to 7), the more excellent superconducting properties are exhibited.

In the present invention, the surface of a superconductor containing at least one element selected from the group consisting of yttrium and lanthanides is coated with a layer of fluoride of the same or another element selected from the above group. This protects the superconductor from water and acids used in processing.

As a result of conducting a test as described below as an example, the present inventor obtained basic knowledge regarding the protective effect of the above-mentioned fluoride coating layer.

For example, on a substrate with an area of about 13 x 1C111, a thickness of 50
When a film of Y-Ba-Cu-0 based superconductor was deposited and immersed in a 0.5 volume solution of 1 part nitric acid and 1 part water, the film was completely dissolved in about 30 seconds. Next, for the same membrane as above, acid was added to nitric acid + hydrofluoric acid decahydrate (4:1:5) 0
．． When the same operation was performed by changing to 5-, it took 30 minutes at the earliest for complete dissolution. By replacing a portion of nitric acid with hydrofluoric acid, the dissolution time was increased by 60 times, and acid resistance was significantly improved. This is because fluoride ions in hydrofluoric acid reacted with Y in Y-Ba-Cu-0 to form indium fluoride (YFs).

Furthermore, an insolubility test of the reaction product of Y and F was conducted using yttrium oxide (Y2O2), which is a raw material for Y in Y-Ba-Cu-0.

Yttrium oxide (ytoi) powder is compressed and shaped into pellets, which are then mixed with hydrofluoric acid (1+1) 1IR1
After immersing the sample in the liquid for 2 minutes, the sample was washed, and the washing liquid and solution were combined to a fixed volume, and the emission intensity of Y was observed using an ICP emission spectrometer. This same Y2O, pellet is again mixed with hydrofluoric acid (1+1).
The sample was immersed in 1IR1 (for 2 minutes), and the second elution amount and the first elution amount were compared based on the ICP emission intensity. As a result, the emission intensity of Y was reduced by half. This is because YP was formed on the surface of the pellet during the first immersion and suppressed elution during the second immersion.

However, the Y2O3 pellets used in this test were compressed and shaped powders and had rough grain boundaries, so even though the surface of each particle was YF, no coating layer was formed to cover the pellet surface. . Therefore, the second hydrofluoric acid penetrated into the unreacted Y2O3 inside the pellet and eluted Y.

The present invention has been made based on the above findings. The fluoride coating layer according to the present invention has a protective effect against water, nitric acid, hydrochloric acid, hydrofluoric acid, etc. As explained above, the presence or absence of a protective effect of fluoride against the acid to be used for processing is determined in advance by immersion testing of pellets of raw material such as ζ oxide in hydrofluoric acid or in an acid containing hydrofluoric acid. can do.

In the above tests, examples of superconductors containing yttrium were explained, but superconductors containing lanthanides instead of yttrium or together with yttrium, such as La-Ba-CuO system, La-5r-Cu-0 system, etc. In the case of superconductors, fluoride, a lanthanide whose chemical properties are very similar to yttrium, exerts a similar protective effect.

Furthermore, although the protective effect of indium or lanthanide fluoride contained in the superconductor has been described, the same protective effect also exists for indium or lanthanide fluoride that is not contained in the superconductor. For example, La-
The surface of the Ba-Cu-0 superconductor is coated with a layer of YF3 or La
Other lanthanoids may be coated with a fluoride layer.

Furthermore, the coating layer may be formed of a fluoride of a plurality of elements selected from yttrium and lanthanoids.

The coating layer of the present invention can be formed by sputtering, vapor deposition, or CVD.
It is deposited and formed on the surface of a superconductor by a method normally used for forming a superconductor, such as a method such as a method.

[Function] According to the present invention, the surface of a superconductor containing at least one first element selected from the group consisting of yttrium and lanthanoids is coated with at least one second element selected from the above group. Coated with a layer of elemental fluoride, the protective action of this fluoride against water and acids prevents dissolution of the superconductor.

Therefore, the superconductor is not damaged in various processes using water and/or acids.

The invention will now be explained in more detail by means of examples with reference to the accompanying drawings.

[Example 1] FIG. 1 shows an embodiment of the superconducting composite material of the present invention.

YJazCusOi, 9 on the sapphire substrate 11
A superconductor thin film 12 (thickness: 4000 mm) having the composition was formed by high-frequency magnetron sputtering, and a YFI coating layer 13 (thickness: 4000 mm) was further formed thereon by plasma CVD.

[Example 2] Similarly to Example 1, YtBa was deposited on the sapphire substrate 11'.
Superconductor thin film 12' having a composition of zCusOi, 9
was formed. Next, a coating layer 13' (6000 layers thick) of LaF was formed thereon by electron beam evaporation.

The superconductor composite materials obtained in Examples 1 and 2 were treated with nitric acid,
It was immersed in a solution of hydrofluoric acid and hydrochloric acid (acid:water = 1:1) for 1 hour, respectively. As a result of observation using a post-immersion microscope and a scanning electron microscope, no damage due to dissolution was observed. Further, IPC analysis was performed on the solution after immersion, but no superconductor elements were detected.

For comparison, a sample in which a superconductor thin film was formed on a sapphire substrate as in Example 1 but without a coating layer was immersed in the same solution as above. In either solution, the 4-body thin film was completely dissolved 15 to 30 seconds after immersion.

〔Effect of the invention〕

Since the superconducting composite material of the present invention does not dissolve in water or acid, it has the effect of being able to perform various necessary processing without damaging the superconductor, so it can be used as a superconductor in a wide range of applications. This will greatly contribute to the practical application of the technology.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the superconducting composite material of the present invention. 11, 11'... Sapphire substrate, 12, 12
'... Superconductor thin film, 13, 13 '... Covering layer.

Claims (1)

[Claims] 1. A superconductor containing at least one first element selected from the group consisting of yttrium and lanthanides, and a superconductor selected from the group consisting of yttrium and lanthanides covering the surface of the superconductor. A superconducting composite material comprising a coating layer of at least one second elemental fluoride.