JPS63255978A - Manufacture of superconducting ceramic substrate - Google Patents

Abstract

PURPOSE:To obtain a superconductor ceramic substrate with superconductor layer in higher marginal temperature formed into one body with the substrate by a method wherein the whole surface of substrate formed of a superconductor ceramic material made of at least presintered ceramics is heated to be melted. CONSTITUTION:The whole surface of a substrate 1 formed of a superconductor ceramic material made of at least presintered ceramics is heated to be melted. At this time, it is recommended that after mixing the material, at least one time of a series of processes of presintering and crushing the presintered ceramics body shall be performed. Through these procedures, the ceramics material can be formed into one body with the substrate part 1b to manufacture the substrate 1 with a superconductor layer 1a in higher marginal temperature than that of substrate part 1b.

Description

Detailed Description of the Invention <Field of Application of Industry-L> The present invention relates to a method for manufacturing a superconducting ceramic substrate, and more particularly to a method for manufacturing a superconducting ceramic substrate in which a superconducting IA is formed on the surface of the substrate.

Problems to be solved by conventional techniques and inventions
Metal-based, ceramic-based, and organic-based superconducting materials are known, and among these, ceramic-based materials have been attracting attention in recent years. In addition, the above-mentioned superconducting ceramics include layered perovskite type (K2N
Oxide superconducting ceramics having a structure of iF4 type are known. The above-mentioned oxide superconducting ceramics are produced through a process of mixing oxide powder as a raw material, compression molding it into a predetermined shape such as a block or sheet, and sintering it. Ceramics exhibit critical temperatures of 30°C or higher.

However, since the above-mentioned superconducting ceramics are manufactured by heating the entire compact and going through a sintering process, it is difficult to form a superconducting layer on the surface of the compact that has a higher critical temperature than the inside. In addition, they do not exhibit sufficient critical properties and have a low critical temperature.

Furthermore, when designing an element having a superconducting layer, it is conceivable to laminate the above-mentioned superconducting ceramics on a substrate, but in this case, not only would the substrate and the superconducting ceramics have to be manufactured separately, but the superconducting material would also have to be fabricated separately. Since it is ceramic-based, it does not have sufficient bonding properties with the substrate (
, there is a problem of lack of unity.

Therefore, according to the conventional method described above, it is difficult to form a superconducting layer with excellent integrity and a high critical temperature on a substrate.

<Purpose of the Invention> This invention was made in view of the above problems, and it is possible to fabricate a substrate and a superconducting layer separately, and to integrate the superconducting layer having a high critical temperature and the substrate without laminating the two. An object of the present invention is to provide a method for manufacturing a superconducting ceramic substrate that can easily manufacture a superconducting ceramic substrate.

Means and Effects for Solving the Problems> In order to achieve the above object, the method for manufacturing a superconducting ceramic substrate of the present invention provides a method for manufacturing a superconducting ceramic substrate, in which a substrate made of a ceramic obtained by molding a superconducting ceramic raw material and at least preliminary sintering. It is characterized by heating and melting the entire surface of the material.

According to the method for manufacturing a superconducting ceramic substrate having the above configuration, the entire surface of the U plate made of ceramic obtained by molding the superconducting ceramic raw material and at least preliminary sintering is heated and melted, so that the surface layer of the substrate is heated and melted. A superconducting layer that is homogeneous and exhibits a high critical temperature can be formed, and the superconducting layer is integrated with the substrate.

The present invention will be explained in detail below.

Any superconducting ceramic raw material can be used as long as it contains elements that can constitute a superconducting substance, including elements of group Ia, group IIa and III of the periodic table.
At least one element selected from Group A elements, at least one element selected from Group Ib elements, Group Nb elements, and Group IIIb elements of the periodic table, and oxygen, fluorine,
Preferably, the constituent element is at least one element selected from sulfur, carbon, and nitrogen.

More specifically, among Group I elements of the periodic table, Group Ia elements include LisNaSK%Rb%Cs, and Group Ib elements include Cu, Ag, and Au.
can be mentioned. Also, among the elements of group II of the periodic table, IIa
The family elements are: B e s M g % Ca % S
r, Ba and Ra, and nb group elements include:
Examples include Z n % Cd. Among the elements of group 1 of the periodic table, examples of group ma elements include Sc, Y, lanthanoid elements such as La5Ce and Gd5Lu, and actinide elements A C% T h sPa and Cf. In addition, as a group IIb element, AJSGaS
Examples include Ins Tj and the like.

Among the above elements, at least one element selected from Group Ib elements of the periodic table, at least one element selected from Group IIa elements, and at least one element selected from Group A elements. It is preferable to use oxygen as a constituent element.

In addition, Cu is an element of Group Ib of the periodic table.

Ag1, especially Cu, is preferable, and among group IIa elements,
Sr, Ba, and Ca are preferred, and among the Ma group elements, ScsYsLa is preferred.

In addition, one or more types of raw materials containing the above elements are used in the form of powder, and the powder includes oxides, carbonates, fluorides, sulfides, carbides and Compounds such as nitrides are used. Among the above compounds, oxygen-containing oxides or carbonates, particularly oxides, are preferred. Moreover, in order to obtain a superconducting ceramic exhibiting a high critical temperature, the above-mentioned raw material preferably contains at least copper oxide CuO.

The above raw materials may be molded and at least pre-sintered to form a substrate made of ceramics, but composite ceramics such as more homogeneous and low melting point composite oxides (hereinafter simply referred to as composite oxides) can be obtained. Therefore, after mixing the raw materials, a series of steps of forming, pre-sintering, and pulverizing the pre-sintered ceramic body are performed at least once to obtain ceramic powder, and the ceramic powder is formed and at least pre-sintered. It is preferable to obtain a substrate made of ceramics.

The preliminary sintering step may be performed under various atmospheres, but in order to prevent the raw materials from being decomposed or reduced and to obtain a homogeneous composite oxide, the preliminary sintering step may be performed under oxygen storage, for example, under oxygen Preferably, the sintering is carried out in an oxygen-containing atmosphere with a partial pressure of 150 to 760 mm/g, and presintering conditions such as heating temperature and heating time are used.

It is selected as appropriate depending on the raw material, etc.

By performing the above series of steps at least once, even if a material with a high melting point is used as a superconducting ceramic raw material, a composite oxide with a low melting point can be obtained by a solid-tti reaction in a solid phase state.

That is, the above-mentioned raw materials generally have a high melting point and must be sintered at high temperatures and for long periods of time. Further, even if sintered under the above conditions, there is no guarantee that the surface layer and the interior of the ceramic will be homogeneous. However, by performing the above series of steps at least once,
Ceramics that are homogeneous throughout can be obtained. For example, as raw materials Y203, BaCO3 and CuO
When producing ceramics having a composition of YBaCuO using
It is a high melting point material that is difficult to melt and requires sintering at high temperatures for a long time. In addition, since the melting point range of each raw material used differs greatly, it is not only necessary to set the sintering conditions to conditions suitable for the high melting point raw material, but even if sintered under the above conditions, the uniformity of the composition It is difficult to obtain suitable ceramics. However, by going through the above series of steps, due to the solid phase reaction in the pre-sintering step,
Composite oxides with low melting points can be produced. That is, after mixing the raw materials, the desired composite oxide can be obtained by compression molding, preliminary sintering, and pulverization steps, and the composite oxide thus obtained has a melting point of 90.
The temperature ranges from 0 to 1400°C, and the melting temperature is narrower and lower than that of the above raw materials. Therefore, by going through the series of steps described above, not only the subsequent molding and sintering can be easily performed, but also homogeneous ceramic powder can be obtained.

Note that the series of steps described above may be performed at least once depending on the raw materials used, the desired composite oxide, and the like.

In addition, whether or not the desired composite oxide is produced can be confirmed by analytical means such as X-ray diffraction, so depending on the raw materials used, sintering conditions, etc. By checking whether or not oxides are generated, it is possible to set the number of repetitions of the series of steps described above. Moreover, the above-mentioned pulverization can be performed using a ball mill or the like.

Since the ceramic material obtained as described above is composed of a composite oxide having a low melting point, the ceramic powder can be easily molded and sintered under low temperature conditions.

Next, the raw materials and the ceramic powder obtained through the series of steps described above are molded and at least presintered to obtain a substrate made of ceramics. Note that in order to obtain an integrated substrate, at least the above-mentioned preliminary sintering may be performed, or main sintering may be performed in order to further improve the integrity of the substrate. Further, since a superconducting layer having a high critical temperature and H degree is formed by heating and melting the entire surface of the substrate, the critical temperature of the substrate obtained as described above may be low. Furthermore, the ME obtained using the above ceramic powder is
Since the ceramic powder is made of a homogeneous composite oxide, it has superconducting properties and a high critical la degree. Note that the critical temperature of the substrate can be controlled by adjusting the number of repetitions of the series of steps described above. In addition, in the above molding process, it is possible to mold into an appropriate shape such as a block shape or a sheet shape, and the preliminary sintering and main sintering conditions are as follows:
It is appropriately selected depending on the raw material, the melting point of the ceramic powder, and the desired characteristics of the substrate.

As mentioned above, the substrate made of ceramics exhibits a high critical temperature, but in order to form a superconducting layer on the surface of the substrate that maintains an even higher critical temperature,
Those having a composition represented by the following general formula (1) are preferable.

AaBbCc (1) (wherein A is at least one element selected from group Ia elements, group IIa elements, and group ■a elements of the periodic table; B is an element of group Ib, group nb of the periodic table; and IIIb
At least one element selected from group elements, C is oxygen,
In particular, the ceramics (representing at least one element selected from fluorine, nitrogen, carbon and sulfur) include Y BaCu O.

0.3 0.7 3 [LaBa] 2 Cuba, [LaS r] 2 CaO2 and [Preferably selected from LaCaco2CuO4.

Then, in order to form a superconducting layer on the surface of the ceramic substrate, the entire surface of the substrate is heated and melted. More specifically, as shown in FIG.
2), and the lens (3) held inside the cylinder (2) focuses the laser beam in a defocused state to form a spot on the surface of the substrate (1) and irradiates it. while moving the irradiation area. At that time, in order to supply oxygen to the surface of the substrate (1), oxygen gas or a mixed gas with a high oxygen partial pressure is supplied to the cylinder (2), and the tip and end of the nozzle-shaped cylinder (2) are Then, spray onto the surface of the substrate (1). The heating and melting may be carried out under various atmospheres, but it is important to prevent the oxides constituting the ceramics from being reduced or decomposed, and to apply a high critical l! to the surface of the substrate. ! In order to form a superconducting layer exhibiting a high
It is preferable to heat and melt the substrate while supplying oxygen to the surface of the substrate by a method such as blowing a mixed gas of 60 mmHg onto the heated melting portion.

By the above operations, as shown in FIG. 2, a substrate (1) having a superconducting layer (la) that is integrated with the substrate part (tb) and has a higher critical temperature than the substrate part (b) is formed. Obtainable.

Although hot air, flame, or the like may be used to heat and melt the surface of the substrate, it is preferable to use a high-output laser in order to efficiently heat and melt the surface.

Examples of the laser include a ruby laser, a glass laser, a solid laser such as a YAG laser with a wavelength of 1.061,
Examples include a He-Ne laser, a Kr+ laser, an Ar+ laser, an excimer laser, a gas laser such as a CO2 laser with a wavelength of 10.6 μm, and a semiconductor laser. Furthermore, in order to increase the processing efficiency of the substrate surface, these laser beams are preferably focused by a lens and irradiated onto the substrate surface, as described above. In addition, in the irradiation operation, the laser beam may be irradiated onto the substrate surface in a focused state and the irradiation location may be moved, but in order to increase the processing efficiency of the substrate surface, it is necessary to irradiate the substrate surface in a defocused state as described above. It is preferable to form a spot on the surface and irradiate it to locally heat it, and to heat and melt the entire surface of the substrate by sequentially moving the irradiated area.

The method for manufacturing a superconducting ceramic substrate of the present invention can produce a substrate integrated with a superconducting layer, so it can be used for switching elements, memory elements, magnetic flux sensors, etc. used in various fields such as electronics fields and electric power application fields. It is useful in manufacturing amplification elements, temperature sensors, etc.

<Examples> The present invention will be described in more detail below based on Examples.

Y2O3 powder and BaC as raw materials for superconducting ceramics
Predetermined amounts of O3 powder and CuO powder were weighed and mixed. Next, the above-mentioned mixed powder was compression molded into a sheet shape under conditions of 100 atm at room temperature and atmospheric atmosphere, and was placed in a mixed gas atmosphere of oxygen gas and nitrogen gas (oxygen gas partial pressure 200 mm l!g).
) for 24 hours at 940°C. Further, the obtained pre-sintered ceramic body was ground in a ball mill.

Note that the above series of steps was repeated 0.3 0.7 3 until Y BaCu O, which is a composite oxide, was confirmed by X-ray diffraction.

The ceramic powder, which is a composite oxide obtained as described above, is compression-molded into a sheet shape and sintered under the same conditions as above to produce a substrate, while blowing oxygen gas onto the surface of the substrate. , CO with output 50~500W
2 laser in a defocused state using a lens 1 to 5
A spot of about mmφ is formed and irradiated onto the substrate surface,
While locally heating and melting the substrate surface, the local heating section was moved to heat and melt the entire surface of the substrate.

Then, when we measured the critical temperature based on electrical resistance, we found that
The results shown in FIG. 3 were obtained. That is, the surface layer of the substrate heated and melted by the laser beam shows a superconducting state at a temperature of 80° C. or less, the substrate part shows a superconducting state at a temperature of 30° C. or less, and the substrate part shows a superconducting state at a temperature of 30° C. It was found that by cooling, the substrate part becomes a relatively insulating layer and the surface part becomes a superconducting layer.

<Effects of the Invention> As described above, according to the method for manufacturing a superconducting ceramic substrate of the present invention, a superconducting ceramic raw material is molded and at least the entire surface of the substrate made of pre-sintered ceramics is heated and melted. The unique effect is that a superconducting layer that is integrated with the substrate and has a high critical temperature can be easily formed on the surface layer of the substrate.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of the heating and melting process in the method for manufacturing a superconducting ceramic substrate of the present invention, Fig. 2 is a schematic cross-sectional view showing an outline of the superconducting ceramic substrate, and Fig. 3 is a diagram showing the results of an example. It is. (1)...Substrate, (Ia)...Superconducting layer, (Ib)
...Substrate part 1N Ib Figure 3 Wet layer (in) Procedure amendment (self-imposed) 5゜] -6゜

Claims (1)

[Scope of Claims] 1. A method for producing a superconducting ceramic substrate, which comprises molding a superconducting ceramic raw material and heating and melting the entire surface of a ceramic substrate obtained by at least preliminary sintering. 2. After the ceramic substrate is mixed with raw materials,
A series of steps of forming, pre-sintering and pulverizing the pre-sintered ceramic body are performed at least once to obtain ceramic powder, and the ceramic powder is formed,
The method for manufacturing a superconducting ceramic substrate according to claim 1, which is at least pre-sintered. 3. The raw materials are Group Ia elements of the periodic table, Group IIa elements, and
At least one element selected from group IIIa elements, at least one element selected from group Ib elements, group IIb elements, and group IIIb elements of the periodic table, and at least one element selected from oxygen, fluorine, sulfur, carbon, and nitrogen. The method for manufacturing a superconducting ceramic substrate according to claim 1 or 2, wherein the superconducting ceramic substrate contains at least one element. 4. The method for manufacturing a superconducting ceramic substrate according to any one of claims 1 to 3, wherein the raw material contains at least copper oxide. 5. The method for manufacturing a superconducting ceramic substrate according to claim 1, characterized in that the entire surface of the substrate is heated and melted under oxygen preservation. 6. The method for manufacturing a superconducting ceramic substrate according to claim 1 or 5, wherein the surface of the substrate is heated and melted with a laser beam while supplying oxygen to the surface of the substrate. 7. Ceramics are Y_0_. _3BaCu_0_. _7O_3, [LaBa]_2CuO_4, [LaSr]_2CuO_4, and [LaCa]_2CuO_4.