JPS63318016A - Superconductive oxide ceramics material - Google Patents

Abstract

PURPOSE:To provide superconductive ceramics of oxide type, which is excellent in anti-water and anti-moisture characteristics and stable when used in contact with water or under high humidity condition, by furnishing a glass type protec tion layer. CONSTITUTION:Glass type protection layer is furnished on superconductive ceramics of oxide type either directly or with any necessary layer interposed. The glass used is out of restriction, and the thickness of the protection layer preferably lies within the extent 0.01-100mum, but in general between 5 and 20mum. Accordingly the material excels in anti-water and anti-moisture characteristics, and the superconductive ceramics of oxide type will never be dissolved even under the environment of contacting water or under high humid ity condition. Thus stable sintered body, wire, different types of elements are obtained, whose superconductive characteristics will never be deteriorated.

Description

[Detailed description of the invention] Background of the invention Technical field The present invention relates to superconducting oxide ceramic materials.

Prior art and its problems Superconducting phenomena below the critical temperature have attracted attention, and superconducting magnets,
Attempts are being made to put it to practical use in power storage systems, Josephson devices, ultra-high-speed computers, medical tomography, large particle accelerators, magnetic levitation trains, etc.

Conventionally, alloys such as Nb have been commonly used as superconducting materials exhibiting superconducting phenomena. However, these alloys, such as Nb3Ge, have a critical temperature of 23 which exhibits superconductivity, which is too low to be practical. On the other hand, ceramic superconducting materials are also known, but for example, LjTi04 has a critical temperature at which it exhibits superconductivity as low as 15. However,
In recent years, ceramics with high critical temperatures that exhibit superconductivity have been developed one after another, paving the way for practical application.

For example, La2-x Bax (: 40 for u04
1Bao, Byo, 400103 exceeds 100K (Z.

Phys, B-Condensed Matter 6
4189-193 (1986), Chemical Industry Daily, Showa 6
March 11, 2015, page 10, etc.].

However, these superconducting oxide ceramics can be decomposed by water, so sintered bodies made of them,
When wires, various elements, etc. are used in environments where they come into contact with water or under high humidity conditions, for example, there is a risk that various properties such as superconductivity may deteriorate.

■Object of the Invention The object of the present invention is to provide a superconducting oxide ceramic material that has excellent water resistance and moisture resistance and is stable even when used in environments where it comes into contact with water or under high humidity conditions.

■Disclosure of invention Such objects are achieved by the present invention as described below.

That is, the present invention is a superconducting oxide ceramic material characterized by having a glassy protective layer.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The oxide ceramic having superconductivity used in the superconducting oxide ceramic material of the present invention is a composite oxide of a rare earth metal element, an alkaline earth metal element, and copper.

According to the present invention, it is possible to improve the water resistance and moisture resistance of sintered bodies, wire rods, various elements, etc. using such composite oxides, but when used for these purposes, string conductive oxide ceramics It is preferable that the composition is a composite oxide as shown below in terms of high critical temperature and the like.

M, R, CuO2 In this case, M is one or more alkaline earth metal elements, among which one or more selected from Ba, Sr and Ca, especially Ba and Sr.
Preferably, one or two selected from the following.
In addition, when M is Ba and/or Sr and Ca, it is preferable that Ba and/or Sr is 50% or more with respect to Ca.

R is one or more rare earth metal elements (Sc, Y, lanthanide elements and actinide elements), and among these, Y and lanthanide elements (L a ”-L
one or more selected from u ), especially Y, L
a%Nd, Eu.

One or two selected from Er, Ho, Dy and Yb
It is preferable that these are at least one species of other lanthanide elements (Ce, Pr, etc.).

Pm, 5m% Gd, Tb, Tm, Lu). Among these, Ce
, Pr, Sm, and Tb are preferred.

When one or more of such lanthanoid elements is substituted, the amount of substitution in R is preferably 80 at% or less, particularly 50 at% or less.

In addition, Ag within a range of 50 at% or less with respect to Cu,
Hg, Ni, Zn, etc. may be substituted.

It is preferable that x+y is 0.7 to 3.0 degree, and x
/ x + y is 0.3 to 0.9, more preferably 0
．． It is 4-0.8.

In Z, R is trivalent (tetravalent in Ce), M is divalent, and C
u is a value near the value calculated as a bivalent value.

These composite oxides are described in Japanese Patent Application No. 62-091706, No. 62-102718, and No. 62-102718 by the present applicant.
It is described in No. 2-102719 and No. 62-102720.

With such a composition, a critical temperature Tc of 40 or more can be obtained.

The rare earth elements Ba and Sr in M and the rare earth elements in R may be contained individually or in combination. When added in combination, the respective quantitative ratios are arbitrary.

Such a composite oxide has a perovskite or perovskite-like structure.

Raw materials for such composite oxides include, for example, Y, L
oxides such as a, Nd, Eu, Ba, and Sr, or compounds that become oxides upon heating, such as carbonates, and oxides of Cu, such as Y2O3, La2O3, Nd2O3, Eu2O3, Er2O3, BaCO3, SrCO3, C
aCO3, CuO, etc. may be used. In addition to these, oxides corresponding to R and M above can be appropriately selected and used.

Such raw materials are mixed using a ball mill or the like, and are subjected to a predetermined heat treatment after being mixed as a powder or temporarily pressed.

For example, in the production of powder, this heat treatment is for forming the above-mentioned composite oxide and imparting superconductivity, and in the production of sintered bodies, it is a so-called calcination step. .

After this heat treatment, it is usually ground to obtain a superconducting oxide ceramic powder.

After this heat treatment, a binder component is usually added as required, and the material is molded and sintered to obtain a superconducting oxide ceramic sintered body. The sintered body may be subjected to an annealing treatment.

Further, the sintered body may be a thick film formed by a printing method in which a binder and a solvent are added to form a paste, and this paste is printed and sintered. In the case of paste printing, a thick film may be obtained by a green sheet method in which printing is performed on a so-called green sheet of ceramic material, and if necessary, the sheets are laminated and sintered, or a thick film may be obtained by laminating various pastes, etc. It may also be a hybrid type thick film that is sintered.

In addition to such powders and thick film or bulk sintered bodies, the above-mentioned superconducting oxide ceramics may be formed into thin films such as vapor-grown films.

The thin film may be, for example, a sputtered film using the above-mentioned sintered body as a target or a multi-source sputtered film using raw material oxide or the like as a target. Also,
For example, it may be a plasma CVD film using a corresponding organometallic compound as a source.

These thin films are subjected to heat treatment if necessary.

In addition, various coating films are also possible. As for the coating film, dipping, thermal spraying, and some I/X coating methods can be used.

This coating film is also subjected to heat treatment if necessary.

When producing these various thin films, coating films, etc., they may be formed as oxides, or may be formed as compounds that become oxides when heated. Examples of compounds that become oxides when heated include the above-mentioned carbonates.

In addition, using organometallic compounds such as metal alkoxides,
This may be applied to form an oxide coating film through a sol-gel reaction of the hydrolyzate.

Furthermore, when forming these various films, diffusion with the base material may be performed after the film formation, thereby forming an oxide film.

Alternatively, it may be made into a wire rod or the like according to a so-called high-speed quenching method, and then subjected to a heat treatment.

Regarding the preparation of these superconducting materials, Japanese Patent Application No. 62-064865 and No. 62-064866 filed by the present applicant,
It is described in No. 62-102718, No. 62-102719, No. 62-102720, No. 62-105959, No. 62-107566, etc.

The sintered bodies, powders, various films, etc. of these superconducting oxide ceramics are used as coils, various parts, elements, etc., depending on the intended use. When applying to various parts, elements, etc.
Any conventionally known or other conventionally known superconducting materials can be applied.

In addition, Japanese Patent Application No. 62-081500 filed by the present applicant;
No. 62-096064, No. 62-098305, No. 62-104018, No. 62-105960, No. 6
No. 2-107567, No. 62-107568, No. 62
-108633, patent application dated May 26, 1986 (
1), the patent application dated May 22nd, the patent application dated May 27th, and the patent application (3) dated May 29th, etc. can all be applied to the present invention.

In the present invention, a vitreous protective layer is provided on the various superconducting oxide ceramics described above, either directly or via a necessary intervening layer.

There are no particular limitations on the glass used, and examples include the following.

Compounds containing oxygen, carbon, nitrogen, sulfur, etc.: e.g. 5in
2, Sin, AfiN, AJ2203, Si3 N4
, Zn3% BN% TiO2, TiN, ZrO2 etc. oxides, carbides, nitrides, sulfides, or e.g. AI
, one or more rare earth metals, etc. and Si, O and N
Various glassy inorganic substances such as composite compounds formed from multiple of the above compounds, including those containing.

Glass: For example, a material such as borosilicate glass, barium borosilicate glass, aluminum borosilicate glass, or glass containing Si3N4 or the like may be used. Among them, S i 0240-80
wt% borosilicate glass, barium borosilicate glass, aluminum borosilicate glass, and these SiO2
It is preferable to substitute a part of with Si3N4 or the like.

Low melting point glass; lead borosilicate glass, zinc borosilicate glass, lead glass, etc.

For example, PbO-B203-3 i O2, PbO-Z
nO-3i O2,R20-B2O3-3in2 (R
:Li, Na, K), ZnO-”B203-3in,,
, PbO-, 20-3iO□, etc., with a melting point of about 700°C or less.

The thickness of the protective layer formed from such glassy material is 0.
．． The thickness is preferably about 0.01 to 100 μm, generally about 5 to 20 μm.

If the thickness is less than 0.01 μm, the water resistance and moisture resistance will be insufficient, and if the thickness exceeds 100 μm, the effect of the present invention will not change, so it is not necessary to exceed the above range.

The protective layer made of glass can be formed using various film-forming methods, such as vapor-phase film-forming methods such as sputtering, sol-gel methods using organic compounds, and baking methods, depending on the composition. Examples of combinations of the composition of the vitreous protective layer and its preferred method of layer formation include the following.

1) SiO□, AI203, TiO2, ZrO2,
One or more types of Bad, Cab, MgO, and SrO.

These layers may be formed by various vapor phase film forming methods, such as sputtering, vapor deposition, ion blating, CVD, etc., but the sol-gel method utilizes hydrolysis of organometallic compounds, especially metal alkoxides. The layers may be set by

In the case of the sol-gel method, the silicon alkoxide is, for example, silicon methoxide [S i (OCH
3) 4], silicon ethoxide [S i (OC
2H5) 4, silicon isopropoxide [S i (
0-iso c3H7)4 ], etc. can be used. Further, as the titanium alkoxide, for example, titanium isopropoxide [T i (0-iso C3H
7) 4] , ]Titanium n-butoxide Ti (0-
nC4H9)4 etc. can be used. In addition, various metal alkoxides such as aluminum alkoxide and zirconium alkoxide may be selected in the same manner.

These metal alkoxides are dissolved in a predetermined solvent, coated on a superconducting oxide ceramic material, and dried after hydrolysis to form a protective layer. As the solvent used, alcohols such as methanol, ethanol, propatool, and butanol are used. The concentration is 20-60% of the above raw material compounds.
It may be done so that it is within the range of In this case, stabilizers can also be used.

For coating, a dipping method, a spin cord method, or the like may be used as appropriate depending on the shape of the superconducting oxide ceramic material.

Hydrolysis may normally be carried out at room temperature.

This hydrolysis usually results in the formation of a sol-like network.

Then dry it. Drying at room temperature and 60% relative humidity
It may be carried out under the following conditions, and may be carried out at 200°C or lower, more preferably 120 to 150°C, for about 10 to 30 minutes. There are no particular restrictions on the atmosphere during drying.

After this, heat treatment is performed as necessary to obtain a protective layer. Heat treatment is 1-2 at 200"C to 1000℃
Time should be temporal.

The protective layer formed in this way is 5i02, AIL20
3. T i 02 , ZrO2, Bad%Cab, Mg
It contains one or more types of O1SrO, but especially S1
02 100 wt%, 70-95 wt%5i02-5
~3wt%B2o3.70wt%Sin2-30wt
%Af1203.40~97wt%S i 02-3~
60wt%ZrO2, 70~80wt%SiO2-20
~30wt%Tie2, 66wt%5iQ2-18w
t%P2O3-7wt%An203-9wt%BaO1
62 to 90 wt% SiO2-10 to 38 wt% CaO, etc. are preferred.

The thickness of the protective layer may be controlled by increasing or decreasing the number of times of coating.

The layer thickness of the glassy protective layer obtained in this way is usually 5 to 10 μm, and the superconducting oxide ceramic sintered body,
Suitable for use in superconducting oxide ceramic wires, etc.

1i) (1) Silicon oxide 40-60wt in terms of Si02
%, BaO, Cab, SrO.

50wt of divalent metal oxides such as MgO, ZnO, PbO, etc.
% or less (in terms of divalent metal oxides) and/or 10 wt% or less of alkali metal oxides (in terms of monovalent metal oxides), and boron oxide and/or aluminum oxide. Note that each oxide may have a stoichiometric composition.

(2) Si and other metal or metalloid elements such as Ba and C
a, Sr, Mg, Zn, Pb, etc., one or more of An, H, and at least one of one or more alkali metal elements, and the Si atomic ratio in the total metal or semimetal is 0.3 to 0.9, roughly containing O and N, and having O/(0+N) of 0.4 to 0.8.

These layers may be formed by various vapor phase film forming methods, such as sputtering, vapor deposition, ion blasting, and CVD.

When using the sputtering method, multi-source sputtering using a plurality of targets may be used, or the above-mentioned glassy material may be used as the target.

The thickness of the glassy protective layer obtained by these vapor phase film forming methods is usually 0.01 to 30 μm, and such a glassy protective layer is used for various types of devices such as Josephson elements, magnetic detectors, and infrared sensors. It is suitably used as a superconducting oxide ceramic material for devices, and can also be used for superconducting oxide ceramic materials such as superconducting oxide ceramic sintered bodies and superconducting oxide ceramic wires.

1ii) Low melting point glass The low melting point glass preferably has a melting point of about 700° C. or lower, preferably about 450° C. to 600° C. As such glass, boric acid glass may generally be used.

As boric acid glass, B2O3 contains PbO1ZnO,S
One or more types of iO2 are added, and if necessary, Tl2O3, Bi203, CdolBa
d% Li20゜Na2O, K2O, V20S, A
J2203(7) It consists of a component made by adding one or more kinds, and various compositions can be used.

Among such boric acid glasses, B203-PbO-
ZnO series, B203-PbO-3i02 series, B20. −
The ZnO-3i O2 system is preferred, and any of these systems may contain the above-mentioned Tfi203, etc.
Furthermore, the composition ratio can be selected from a wide range.

In addition, as other low melting point glass, P b OK
20 S i O2 type etc. are mentioned.

The glassy protective layer formed from these low-melting glasses is made by turning the low-melting glasses into powder, dispersing it in a dispersion medium, applying it to a superconducting oxide ceramic material, and heat-treating it to fuse and bond it. It is preferable to form by a so-called baking method.

The particle size of the low melting point glass powder is 0.5 to i.

The thickness is preferably about μm.

As the dispersion medium, an organic solvent is used because the superconducting oxide ceramic material to be coated is decomposed by water.

As the organic solvent, ketones such as methyl ethyl ketone, aromatics such as diethyl phthalate, cyphthyl phthalate, and quidylole, cyclohexanone, butyl carpitol acetate, diacetone alcohol, etc. may be used.

Further, a resin component may be included in the coating dispersion.

The low melting point glass powder dispersed in such a dispersion medium is applied to the superconducting oxide ceramic material by brushing, screen printing, dipping, or the like.

Thereafter, the low melting point glass powder is melted and bonded by heat treatment, usually in a temperature range of 500 to 900°C, to form a vitreous protective layer.

Note that the heat treatment may normally be performed in air, but depending on the case, it may be performed by controlling the oxygen partial pressure or the like.

The thickness of the glassy protective layer obtained in this way is usually 2 to 20 μm, and the superconducting oxide ceramic sintered body,
Suitable for use in superconducting oxide ceramic wires, etc.

Note that various inorganic or organic films may be used as the base layer provided as necessary as the base for the glassy protective layer. Further, a plurality of glassy protective layers may be laminated as necessary.

(2) Specific effects of the invention The superconducting oxide ceramic material of the invention has a vitreous protective layer.

Therefore, the superconducting oxide ceramic material of the present invention has excellent water resistance and moisture resistance, and the superconducting oxide ceramic material does not decompose even when used in an environment where it comes into contact with water or under high humidity conditions. Stable sintered bodies, wires, various elements, etc., whose superconducting properties do not deteriorate, will be realized.

(2) Specific Examples of the Invention The present invention will be described in more detail below with reference to specific examples of the invention.

[Example 1-1] On a sapphire substrate, a paste prepared by dispersing Y, Ba, and Cu composite oxide powder in Chilbionel and adding ethyl cellulose as a binder was applied.
Y I B with a film thickness of 2 μm after firing for 0 ” Cl2O time
A superconducting oxide ceramic film having a composition of a 2 Cu 307-6 was formed.

A glassy protective layer of SiO2 was formed on this superconducting oxide ceramic film by a sol-gel method under the conditions shown below.

Silicon ethoxide was used as a raw material, dissolved in a solvent (ethyl alcohol and a stabilizer) at a concentration of 10%, stirred, and then applied onto the superconducting oxide ceramics using a spin cord.

This was followed by drying at 40% relative humidity and 1 hour at 300"C.
Heat treatment was performed for a period of time.

Such coating and heat treatment steps were repeated 10 times to form a glassy protective layer having the above composition and having a layer thickness of 5 μm.

This product was designated as sample No. 1-1.

[Example 1-21 A 5 μm thick TiO
A vitreous protective layer manufactured by No. 2 was formed.

This product was designated as sample No. 1-2.

[Example 2] A superconducting oxide ceramic thin film was formed on a cosapphire substrate by sputtering using a composite oxide of Y, Ba, and Cu as a target.

Thereafter, the film was heat treated at 910° C. for 2 hours.

The thickness of the obtained thin film was 2 μm, and the composition was Y 1B a 2 Cu 307+δ.

On this thin film, sample No. shown below was applied.

Samples were prepared by forming glassy protective layers 2-1 to 2-4 to a thickness of 2 μm by reactive sputtering (sample Nos. 2-1 to 2-4).

During sputtering, multi-source sputtering was performed as necessary, and the sputtering rate was controlled to be the sputtering rate converted to the following compound.

Sample No. 2-1 Sin2 48.0wt% B2O347.0wt% Na2O3,0wt% 20 2. Owt% The metal composition of the protective layer was almost the same as above.

Sample No. 2-2 Sin2 48.0wt% Al2O36.0wt% B203 12. OV/1% Na2O1.0wt% to 20 1.0wt% BaO20.0wt% CaO10.0wt% ZnO2, Owt% The metal composition of the protective layer was almost the same as above.

Sample No. 2-3 SiO238.0wt% Si3N4 20.0wt% BaO24.0wt% Ca0 18. Owt% The composition of the protective layer is such that the Si atomic ratio in all metals or metalloids is 0.
．． 7, o/(0+N) was 0.73.

Sample No. 2-4 Sin2 21.0wt% Si 3N4 29.0wt% A1203 9.0wt% B2O35.0wt% Ba0 26.0wt% Ca0 10. Qwt% The protective layer composition has a Si atomic ratio of 0 in all metals or semimetals.
．． 6, O/(0+N) was 0.63.

[Example 3-1] On a sapphire substrate, a paste prepared by dispersing Y, Ba, and Cu composite oxide powder in Chilbionel and adding ethyl cellulose as a binder was applied.
Sintered at 0°C for 20 hours to form a film of Y, Ba2Cu with a thickness of 5 μm.
30. −． A superconducting oxide ceramic film having a composition of No. 5 was formed.

A low melting point glass was melted and bonded onto this film by a baking method under the conditions shown below to form a vitreous protective layer.

PbOB2 03-3 i O2 glass powder (particle size 0.5 μm) dispersed in methyl ethyl ketone at a working temperature of 600° C. was applied onto the superconducting oxide ceramic film by screen printing.

This was subjected to heat treatment at 600° C. for 1 hour to melt and bond the above-mentioned glass to form a vitreous protective layer having a thickness of 10 μm.

This product was designated as sample No. 3-1.

[Example 3-2] The low melting point glass used was P b OK at a working temperature of 700°C.
20 SiO2 glass, heat treatment conditions were 7.
A vitreous protective layer was formed in the same manner as in Example 3-1 except that the temperature was 50°C for 1 hour.

This product was designated as sample No. 3-2.

[Comparative Example 1] In Example 1-1 above, a sample without the glassy protective layer was prepared and designated as Comparative Sample 1.

[Comparative Example 2] In Example 2 above, a sample without the glassy protective layer was prepared and designated as Comparative Sample 2.

For each sample obtained in each of the above Examples and Comparative Examples, the superconducting properties at the initial stage and after storage were measured, and changes therein were investigated.

The storage conditions were 30°C and 80% RH for 2 weeks.
Changes in appearance were also observed.

As a result, the superconducting oxide ceramic material (sample No. 1-1.1-2.2) having a vitreous protective layer of the present invention was obtained.
-1 to 2-4.3-1.3-2), there is no deterioration in superconducting properties such as critical temperature and critical current density even after storage.
No abnormality was observed in appearance.

On the other hand, in Comparative Samples 1 and 2, the critical temperature and critical current density decreased, and discoloration was observed on the surface of the superconducting oxide ceramic film, indicating that the superconducting oxide ceramic had decomposed. confirmed.

In addition, as a weather resistance test, changes after being immersed in water for 2 hours were examined. The comparative sample was discolored due to reaction with water, but no change was observed in the sample of the present invention.

From the above examples, the effects of the present invention are clear.

Claims (1)

[Claims] (1) A superconducting oxide ceramic material characterized by having a glassy protective layer.