JPH01219058A - Superconductor and its production - Google Patents

Abstract

PURPOSE:To obtain the subject superconductor with a relative high transition temp., having excellent moldability, and capable of maintaining stabilized performance for a long time by mixing a ceramic superconducting material and glass material powder, melting the mixture, and then calcining the melt. CONSTITUTION:A ceramic superconducting material or the powder of the material is mixed with glass material powder, the mixture is melted, and the melt is calcined to obtain the desired superconductor. The physical and mechanical properties of the mixed glass material do not change the characteristics of the superconducting material, and rather control the most physical and mechanical properties of the superconductor itself. Accordingly, the superconductor has excellent moldability, the superconductor can be easily worked into a wire by molding by a metallic mold, extrusion, drawing, etc., and formed into a film by rolling by rollers, rolling by a metallic mold, etc. In addition, a reduction reaction is controlled by the action of the mixed glass material, ageing deterioration is minimized, and the superconductor is stabilized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ceramic superconductor and a method for producing the same, and in particular, a ceramic superconductor that has a relatively high transition temperature, excellent formability, and stable performance. A superconductor that can be maintained for a long time and a method for manufacturing the same.

[Prior Art] Superconductors have the property of having zero electrical resistance at temperatures below their transition temperature, and are used, for example, as ideal electrical transport media in NMR1 magnetic levitation trains for medical and experimental purposes. Or as a coil material used in superconducting generators, etc.
Alternatively, as a material with coherence, it is expected to be applied as a thin film material for use in Josephson elements and the like.

By the way, in order to bring such applications closer to the level of industrial practical use, it is essential to develop a superconductor that has a transition temperature as high as possible, excellent formability, and does not change over time.

In recent years, a superconductor with an extremely high transition temperature has been developed using the general formula RB az Cu s 0t-y (R=Y.

La, Nd, Sm, Eu, Gd, Dy, Hc.

So-called ceramic-based high-temperature superconductors represented by the general formula (Er, Tm, Yb, Lu) or the general formula (%) have been developed and are attracting attention.

[Problems to be Solved by the Invention] However, such ceramic-based high-temperature superconductors generally have extremely poor moldability and are subject to large changes over time, so they have not yet reached the stage of industrialization.

In other words, at present, for example, in order to manufacture a conducting wire using a ceramic-based high-temperature superconductor, the raw material of the superconducting material is first calcined and pulverized and formed into a rod shape, and then this is mixed with silver,
The wire is drawn into a sheath made of copper or copper alloy, and then sintered. Moreover, this sintering must be performed while supplying oxygen to the center of the conductor, but if sintering is performed with the sheath still covered, this oxygen will react with the sheath metal and the composition ratio of the conductor will be disturbed. Because of this, the sheath had to be peeled off again before sintering.

For this reason, the manufacturing process is extremely complicated and takes a long time to manufacture.Although it can be manufactured in a laboratory,
Industrialization was shaky.

In addition, various physical vapor deposition methods have been attempted to form films with ceramic-based high-temperature superconductors, but the deposition rate is extremely slow, and the films formed by this method have poor reproducibility of superconducting properties. Because of the lack of quality, it was extremely inadequate as a method for forming a large amount of films with uniform quality.

Furthermore, conductive wires or films of ceramic-based high-temperature superconductors manufactured by the method described above often lose oxygen over time and no longer exhibit superconductivity, making them extremely unstable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a superconductor and a method for manufacturing the same that eliminate the above-mentioned problems.

[Means for Solving the Problems] The present invention provides a superconductor in which a ceramic superconducting material is mixed with a glass material as a binder, and a ceramic superconducting material or a raw material powder of the ceramic superconducting material and glass. This is a superconductor manufacturing method in which the superconductor is obtained by mixing the superconductor with a powder of the material, melting it, and then firing it. It has the following configurations, making it possible to manufacture the body at low cost and in large quantities.

(1) A superconductor characterized by containing a ceramic superconducting material and a glass material mixed with this superconducting material as a binding material.

(2) The superconductor according to configuration (1) is produced by mixing a ceramic superconducting material or a raw material powder of a ceramic superconducting material with a powder of a glass material, melting it, and then firing it. A method for manufacturing superconductors.

[Function] The superconductor of the above configuration (1) has the physical and mechanical properties of the superconductor itself without changing the properties of the superconducting material. It maintains a high transition temperature, which is a characteristic of ceramic superconducting materials, and has excellent formability. It has been confirmed that it can be easily processed into a linear shape, and can be formed into a film by roller rolling, mold rolling, etc., and the reduction reaction is suppressed by the action of the mixed glass material, so the change over time is extremely small.
Confirmed to be stable.

Further, according to the configuration (2), the superconductor of the configuration (1) can be manufactured extremely easily, and the superconductor can be manufactured in large quantities at low cost.

[Example] Hereinafter, a superconductor and a method for manufacturing the same according to an example of the present invention will be described in detail.

In addition, as the ceramic superconducting material in the present invention, for example, the general formula, RBat Cu30y (R=Y, L
a, Nd, Sm, Eu, Gd, Dy.

Ho, Er, Tm, Yb, Lu) or (La
Examples include substances expressed by L)2Cub< (L=Ba, Sr).

Further, raw material powder for ceramic superconducting materials includes, for example, Cu, Ba, Sr, Y, La, and Nd.

Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, L
Examples include metal oxides, metal nitrates, metal fluorides, etc. containing metal components such as u. That is, a superconducting material can be obtained by mixing these raw material powders at an appropriate mixing ratio and firing the mixture.

Furthermore, as the glass material, for example, boric acid, phosphoric acid,
Examples include silica that easily becomes glassy by heating and melting and then cooling, or a mixture of two or more of these.

(Example 1) This example is an example in which a superconducting material is manufactured by mixing glass powder with a superconducting material, melting it, and then firing it.

The powder of RtOs, BaO or CuO, which is the raw material for a substance with the general formula % Yb, which is classified as a so-called high-temperature superconducting material with a superconducting transition temperature of 30 or higher, is mixed with R vs. Ba vs. C.
After mixing and pulverizing in a mortar or ball mill so that u is 1:2:3, it is molded in a mold and pressed in a rubber press to make pellets. This is fired at 850° C. to 950° C. for 35 hours, and then slowly cooled at 1° C./min in 02 gas to obtain a pellet-shaped superconducting material. The transition temperature of the superconducting material thus obtained was measured to be 1.92.

Next, the sintered body of the superconducting material thus obtained is mixed with boric acid (0.5 to 2% by mole of the outer layer), mixed and ground again in a mortar or ball mill, and sieved to obtain a particle size of 10
Take out only the powder with a particle size of μm to 50AL11 and press it by molding or directly
Bake at ℃ for 30 minutes. As a result, the melting point of boric acid is 18
Since the temperature is 5° C., this boric acid dissolves and acts as a binder, resulting in a superconductor having a certain shape. The transition temperature of the superconductor thus obtained and the mol% of mixed boric acid
When we investigated the relationship between the two, we obtained the results shown in Figure 1.

In addition, in FIG. 1, the vertical axis represents the transition temperature (K),
The horizontal axis indicates the boric acid concentration (mol%).

(Example 2) This example is an example in which a film-like or rod-like superconductor is obtained directly from raw material powder of a superconducting material.

Y is a raw material of a substance represented by the general formula YBat Cus Oy, which is classified as a so-called high-temperature superconducting substance with a superconducting transition temperature of 30 or higher.
20s, Bao2 or CuO powder Y vs Ba vs Cu
Prepare 70g of a mixture with a ratio of 1:2:3, then make B x Os powder from H and BO3 as a glass material, and apply this to the outside of the superconducting material prepared above. Then, this mixture was put into a platinum crucible, and the crucible was heated to 1300°C in an electric furnace, and this temperature was maintained for 2 hours to melt it. do.

In this case, the crucible is taken out of the electric furnace and stirred every 20 minutes to ensure uniform melting.

Next, this melt is poured between two rotating metal rollers, rolled and rapidly cooled to a thickness of 101 m to 50 m.
071111 in the form of a film.

Next, this film body is fired at 950° C. for 35 hours, and then slowly cooled at a cooling rate of 1° C./min.

When the properties of the membrane thus obtained were investigated, it was confirmed that it was a superconductor with a transition temperature of 81. In this case, X-ray analysis has confirmed that by melting the raw material powder of the superconducting material, the superconducting material itself is mixed extremely well at the atomic level compared to the conventional method of mixing in a mortar. In addition, by mixing boric acid, the melting temperature is lowered (from 1350° C. to 1300° C.) compared to when only the raw material powder of the superconducting material is used, making it easier to melt.

In addition, the molten material melted under the same conditions as above was
, to obtain a linear superconductor having the same characteristics as described above by suctioning it into a glass tube with a wall thickness of 111 mm, rapidly solidifying it, forming it into a linear body, and firing it under the same conditions as above. was completed.

Next, membrane bodies and linear bodies were manufactured with various amounts of boric acid mixed in as the glass material, and other conditions were kept the same as in the previous case, and their properties were investigated.The results were as follows. .

Amount of mixed boric acid (mol%) Transition temperature (K) 1.5
492.0
392.5
□3,0
--In this case, when the mixed boric acid content was 2.5% or more, no superconductivity could be observed in the temperature range of 12 to 300 K.

In addition, when no boric acid is mixed at all, it is not possible to form a film body or a linear body by the above-mentioned rolling method or suction method. , it was only possible to fabricate a film body with a thickness of 2 to 51 nm or more in a laboratory).

Therefore, when a superconductor without boric acid was created using the same method as before, its transition temperature was 87.

The above results almost match the results shown in FIG. 1 above.

(Example 3) In this example, RBat Cus Oy (R=Nd, Gd, Ho
) was used, except that the film body and the linear body were produced in the same manner as in Example 2, and the superconductor was produced without boric acid, which is almost the same as in Example 2. Results are being obtained.

(Example 4) In this example, the superconducting material used in Example 2, YB
a2Cux Y in which Ba of Oy is partially replaced with Sr (
A WA body and a linear body were produced in the same manner as in Example 2, and a superconductor without boric acid was produced in the same manner as in Example 2, except that Ba+-x Srx )2 Cus Oy was used as the superconducting material. The transition temperature was 50K in the case without boric acid and 43K in the case of 1% boric acid.

(Example 5) In this example, the superconducting material used in Example 2, Y
A film body was formed in the same manner as in Example 2, except that YBat Cus (OF)3', in which some of the 0's in B a 2 Cu s Oy were replaced with F''(''), was used as the superconducting material. The transition temperature was 70 K in the case without boric acid and 61 in the case of 1% boric acid.

(Example 6) This example is the same as Example 2 except that B15rCaCu20y was used as the superconducting material and firing was performed at 800°C. The transition temperature in this case was 115K in the case without boric acid and 95K in the case with 1% boric acid.

In addition, in the above examples, when a sample containing 1% boric acid and a sample containing no boric acid were stored in the air at 20°C and their changes over time (stability) were investigated, it was found that no boric acid was present. The transition temperature of the sample decreased by IOK after 2 months, whereas no change was observed in the transition temperature of the sample mixed with boric acid.

[Effects of the Invention] As detailed above, the present invention provides a superconductor in which a ceramic superconductor is mixed with a glass material as a binder, and a ceramic superconductor or a raw material for the ceramic superconductor. This is a superconductor production method in which the superconductor' is obtained by mixing powder and glass powder, melting, and firing. In addition, it has made it possible to manufacture stable superconductors that do not change over time at low cost and in large quantities.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the transition temperatures of superconductors produced by varying the amount of boric acid mixed into the raw material of the superconductor.

Claims (2)

[Claims] (1) A superconductor characterized by containing a ceramic superconducting material and a glass material mixed with this superconducting material as a binding material. (2) The superconductor according to claim (1) is manufactured by mixing a ceramic superconducting material or a raw material powder of a ceramic superconducting material with a powder of a glass material, melting the mixture, and then firing the mixture. Featured methods for manufacturing superconductors.