Superconductor technology: apparatus – material – process – High temperature – per se – Copper containing
Patent
1992-05-20
1994-12-13
Lieberman, Paul
Superconductor technology: apparatus, material, process
High temperature , per se
Copper containing
505775, 505776, 505777, 505778, 505779, 505780, 505781, 505782, 505783, 252518, 252521, H01B 1200, H01L 3112
Patent
active
053729900
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to oxide superconductors adapted for use as magnet coil materials in nuclear fusion furnaces, electromagnetic fluid generators, accelerators, rotary electrical apparatuses (electric motors, generators, etc.). magnetic separators, magnetic floating trains, magnetic floating automobiles, magnetic floating elevators, nuclear magnetic resonance computed tomographs, magnetically-propelled ships, electron beam exposure devices, single crystal manufacturing apparatuses, various laboratory devices, etc., suited for applications which involve the problem of power loss in transmission lines, electrical energy storing devices, transformers, rectifiers, etc., further adapted for use in various elements, such as Josephson devices, SQUID, superconducting transistors, superconducting microwave transmission circuits, and furthermore, adapted for use as various function materials, such as infrared detection materials, magnetic shielding materials, etc.
BACKGROUND OF THE INVENTION
Conventionally approximately twenty kinds copper compound oxide superconductors with different crystal structures are known. Any of these copper compound oxide superconductors commonly includes, in its crystal structure, Cu-O.sub.2 sheets through which superconducting current flows, and a stratified structure composed of repeated units each including the Cu-O.sub.2 sheet and another layer situated at a predetermined distance therefrom.
In the case of the crystal structure of La.sub.2 CuO.sub.4, for example, repeated units each including an La.sub.2 O.sub.2 layer and a Cu-O.sub.2 sheet are arranged in layers in the direction of a c-axis (direction perpendicular to the Cu-O.sub.2 sheet), as shown in FIG. 1. In other words, one Cu-O.sub.2 sheet is sandwiched between earth two La.sub.2 O.sub.2 layers. This structure having one Cu-O.sub.2 sheet between the aforesaid layers, will be referred to as a one-layer system, hereinafter.
In the case of this crystal structure, there is a slip for a 1/2 unit cell in each La.sub.2 O.sub.2 layer with respect to the directions of a- and b-axes (directions within the plane of the Cu-O.sub.2 sheet). Crystallographically, therefore, two La.sub.2 O.sub.2 layers and two Cu-O.sub.2 sheets constitute a repeated unit.
One-layer system oxide superconductors of this type include, for example, Bi.sub.2 Sr.sub.2 CuO.sub.6, Tl.sub.2 Ba.sub.2 CuO.sub.6, Nd.sub.2 CuO.sub.4, and Pb.sub.2 SrLaCu.sub.2 O.sub.6+ .delta., which is described in "Physica C," vol. 166, 1990, pp. 502 to 512.
In the case of the crystal structure of Y.sub.1 Ba.sub.2 Cu.sub.3 O.sub.7, moreover, repeated units each including a BaO-CuO-BaO layer, a first Cu-O.sub.2 sheet, a Y layer, and a second Cu-O.sub.2 sheet are arranged in layers in the direction of the c-axis, as shown in FIG. 2. Therefore, a unit composed of the first Cu-O.sub.2 sheet, Y layer, and second Cu-O.sub.2 sheet is sandwiched between each two BaO-CuO-BaO layers. This structure having two Cu-O.sub.2 sheets in the aforesaid unit will be referred to as a two-layer system, hereinafter.
In the case of this crystal structure, in contrast with the case of the aforementioned La.sub.2 CuO.sub.4, there is no slip with respect to the directions of tile a- and b-axes, so that the aforesaid repeated units are not different from crystallographic versions.
Two-layer system oxide superconductors of this type include, for example, Bi.sub.2 Sr.sub.2 Ca.sub.1 Cu.sub.2 O.sub.8, Tl.sub.2 Ba.sub.2 CaCu.sub.2 O.sub.8 described in "Nature", vol. 332, Mar. 31, 1988, pp. 420 to 422, YBa.sub.2 Cu.sub.4 O.sub.8 described in "Nature", vol. 334, July 14, 1988, pp. 141 to 143, Ba.sub.2 YCu.sub.3 O.sub.7-x described in "Japanese Journal of Applied Physics", vol. 26, No. 5, May, 1987, pp. L649 to La.sub.2-x Ca.sub.1+x Cu.sub.2 O.sub.6-x/2+ .delta. described in "Materials Chemistry", vol. 7, 1982, pp. 413 to 427, and Pb.sub.2 Sr.sub.2 (R, Ca).sub.1 Cu.sub.3 O.sub.8+y (R: rare earth element) described in "Physica C", vol. 157, 1989, pp. 124 to 130.
In the case of the cryst
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Nobumasa Hitoshi
Shimizu Kazuharu
Kopec M.
Lieberman Paul
Toray Industries, Ltd.
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