JPS63318015A - Oxide superconductor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a superconductor of oxide type in which superconductive characteristics are maintained for a long period, by covering the exposed portion of superconductor consisting of ceramics of perovskite type with a passivation film. CONSTITUTION:A superconductive coil 1 is arranged on an insulated based plate 3 with a certain pattern and covered with passivation film 2 to provide a superconductive coil in the form of a printed coil. That is, passivation material is coated on at least on the exposed portion of a sintered body or green body of superconductor consisting of ceramics of perovskite type, and then this mate rial is baked to form a passivation film 2 at this exposed portion. The passivation film 2 prevents intrusion of water etc., to the porous exposed portion of superconductive ceramics and contributes to stability of the oxide. This prevents the superconductor from absorbing moisture and deteriorating to lead to provision of superconductor with a longer life.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxide superconductor and a method for producing the same, and particularly to an oxide superconductor and a method for producing the same that aim to extend the life of high-temperature superconducting properties.

[Conventional technology]

Conventionally, regarding oxide-based superconducting materials and their manufacturing methods,
Zeit Schrift Fuyufujiku B64
(1987) pp. 189-193 (Zeits
chift fur Physik B 64 (19
86) PP189-193), Science 235(1)
987), pp. 567 to 569 (Science
, 235 (1987) P P 567-569)
, and Physical Revue Letters 58 (198
7th year) pages 908 to 910 (Physical
Review Letters 58 (1987)
PP (908-910) and others.

[Problem that the invention seeks to solve]

Although the superconducting transition temperature of perovskite ceramic superconductors is generally higher than that of conventional alloys, it has been difficult to maintain superconducting properties for a long time.

An object of the present invention is to provide an oxide superconductor that can maintain superconducting properties for a long time and a method for producing the same.

[Means for solving problems]

In order to achieve the above object, the oxide superconductor of the present invention is characterized in that the exposed portion of the superconductor made of perovskite ceramics is covered with a passivation film.

[For production]

In the above configuration, a passivation material is applied to at least the exposed portion of a green body or sintered body of a superconductor made of perovskite ceramics, and then this material is fired to form a passivation film on the exposed portion. achieved.

The passivation film prevents moisture from entering the exposed porous parts of the superconducting ceramic and contributes to the stability of the oxide. The synergistic effect of this action prevents the superconductor from deteriorating due to moisture absorption, thereby extending the life of the superconductor.

〔Example〕

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

In this embodiment, the present invention is applied to a printed coil superconducting coil. That is, superconducting coils 1 are arranged in a predetermined pattern on an insulating substrate 3'' and covered with a passivation film.

Although the product shown in FIG. 1 is in the form of a printed coil, the product form to which the present invention can be applied is not limited to this, and can be applied to any of wire rods, thin layered products, and plate-like products. Furthermore, depending on the product, the insulating substrate 3 is not necessarily required.

Next, an example of the manufacturing method will be explained with reference to FIG. First, prepare a perovskite ceramic green body. This preparation may be done in bulk or by disposing the superconducting material in a predetermined pattern on the insulating substrate 3.

Then, in the first firing, the above material (green body)
sinter. The firing temperature is, for example, 900-1 as described below.
The temperature is 100°C.

Apply cooled alt passivation film material. Examples of insulating materials include fractions of magnesia (MgO), alumina (AQ203), and sapphire powders in solvents, polyimide resins, polyimide isoindoquinazolinedione (PIQ) resins, and polyamic acids thereof. , polyamic acid, etc., whether organic or inorganic. By secondary firing these, magnesia film, alumina film, sapphire film, polyimide film, PIQ
A film is formed.

However, the temperature of the second firing must be lower than the temperature of the first firing. This is to prevent loss of superconducting properties.

Hereinafter, superconducting materials applicable to this example will be schematically explained.

(corresponds to 77) - (corresponds to liquid N2 temperature) The high temperature superconducting material used in this example is, for example, a ternary oxide (ceramics) of yttrium, barium, and copper.
．． This material was developed by the Science and Technology Agency's Institute for Metals and Materials, and its superconductivity breaks when a 5 Tesla magnetic field is applied, and the superconducting state can be maintained even when the amount of current changes from 0.02A/ffl to 0.2A/c+#. (Refer to the Nikkan Kogyo Shimbun dated March 3, 1986).

(Corresponding to 123) The high-temperature superconducting material used in this example is, for example, a so-called cupic perobsite whose chemical formula is represented by the general formula ABO, and a specific example thereof is (αx-Xβx)'C
It is represented by u O3-y.

In the above, X is 0≦X≦1. y is 0≦y<1+ αtβ is an element belonging to subgroup A of group II of the periodic table, such as scandium (Sc), yttrium (Y), and lanthanum (La), respectively;
Indicates elements belonging to subgroup a of group I of the periodic table, such as calcium (C, a), strontium (Sr), and barium (Ba).

The manufacturing method of such a so-called high-temperature superconducting material is, for example, La2O
3. Oxides of group IIIa elements such as Y2O3 and Baco3
．． It is obtained by mixing a carbonate of a group Ila element such as 5rC03, Ca, GO, etc. and copper oxide (CuO) in powder form and sintering the mixture. Perovskite, which is heated and hardened at 900 to 1100°C in the ratio of 0.6 barium, 0.4 yttrium (therefore, x = 0.4), 1 copper, and 3 oxygen (therefore, y = 0), has a superconducting onset temperature. The superconducting end point at which the resistance becomes completely zero is approximately 90 or more.

(Compatible with -40℃) The high temperature superconducting material used in this example may be a new oxide-based material developed by the research group of Professor Paul Chu of the University of California, Lawrence Berkeley Laboratory or Hyuston College. (See Yomiuri Shimbun dated March 5, 1982; Yomiuri Shimbun dated May 24, 1986).

(Compatible with -13℃) The high-temperature superconducting material used in this example may be, for example, a perovskite-type ceramic superconducting material of yttrium-barium-copper-oxygen thread discovered by Energy Conversion Devices Inc. of New York, USA (1988). (See Nihon Keizai Shimbun, May 29).

(Compatible with 7°C) The high-temperature superconducting material used in this example may be, for example, a perovskite-type ceramic superconducting material made by adding fluorine to yttrium-barium-copper oxides published by Energy Conversion Devices, Inc. of the United States. (Refer to the Nihon Keizai Shimbun dated June 9, 1988).

(Compatible with 35°C) Materials containing scandium, strontium, and other metal elements can be used in oxides of yttrium, barium, and copper, as announced by the Moscow University Group (June 9, 1988).
(See Nihon Keizai Shimbun, dated).

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to maintain superconducting properties for a long time.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an oxide superconductor according to an embodiment of the present invention, and FIG. 2 is a flow diagram of a method for manufacturing an oxide superconductor according to an embodiment of the present invention. 1... superconducting coil, 2... passivation film,
3...Insulating substrate.

Claims (1)

[Claims] 1. An oxide superconductor characterized in that an exposed portion of a superconductor made of perovskite ceramics is covered with a passivation film. 2. A passivation film is formed on the exposed portion by applying a passivation material to at least the exposed portion of the green body or sintered body of the superconductor made of perovskite ceramics and then firing the material. Method for manufacturing oxide superconductors.