Kabushiki Kaisha Kobe Seiko Sho

Kyocera Corporation

The Tokyo Electric Power Company, Incorporated

International Superconductivity Technology Center

Matsushita Electric Industrial Co., Ltd.

Mitsubishi Metal Corporation

Mitsubushi Metal Corporation

Japan Superconductor Technology Inc.

Takayuki Miyatake

Shoji Tanaka

Nobuo Suzuki

Takahiro Wada

Takeshi Sakurai

Naoki Koshizuka

Kyoji Zaitsu

Takayoshi Miyazaki

Hiroyuki Kato

Shinichi Koriyama

Hisao Yamauchi

Takashi Hase

Shin-ichi Koriyama

Satoshi Kizaki

A precursor for manufacturing a NbSn superconducting wire according to the present invention includes a mono-element wire including a Sn or Sn-based alloy core disposed at the, a Cu or Cu-based alloy matrix and a plurality of Nb or Nb-based alloy filaments surrounding the Sn or Sn-based alloy core, and a diffusion barrier layer and a stabilizing copper layer surrounding the Cu or Cu-based alloy matrix. In a final shape after a reduction process, the average diameter of the Nb or Nb-based alloy filaments is set to 5 &#x3bc;m to 30 &#x3bc;m, and the average distance between the Sn or Sn-based alloy core and the Nb or Nb-based alloy filaments nearest the Sn or Sn-based alloy core is set to 100 &#x3bc;m or less.

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A method for manufacturing a powder-metallurgy processed NbSn superconducting wire is provided. In the method, a sheath made of Nb or a Nb alloy is filled with a raw material powder containing Sn. The sheath filled with the raw material powder is subjected to diameter reduction to form a wire. The wire is heat-treated to form a superconducting phase at the internal surface of the sheath. The raw material powder is prepared by adding a Sn powder to a Cu&#x2014;Sn alloy powder or a Cu&#x2014;Sn intermetallic compound powder, and is compacted under isotropic pressure.

Disclosed herein are high-temperature oxide superconductors of RBa.sub.2 Cu.sub.4 O.sub.8 type, with Ba partly replaced by Sr or Ca, or with R and Ba partly replaced by Ca and Sr, respectively, as represented by the chemical composition formula of R(Ba.sub.1-y Sr.sub.y).sub.2 Cu.sub.4 O.sub.8 or R(Ba.sub.1-z Ca.sub.z).sub.2 Cu.sub.4 O.sub.8 or (R.sub.1-x Ca.sub.x) (Ba.sub.1-y Sr.sub.y).sub.2 Cu.sub.4 O.sub.8. They exhibit superconductivity at high temperatures. Especially, the last one exhibits superconductivity at a higher temperature than the former two. All of them can be made with a less amount of Ba as a deleterious substance, and the first two have improved sinterability. The best results are obtained when they are produced by the process involving the hot hydrostatic pressure treatment of the mixture of raw materials at 850.degree.-1100.degree. C. in an atmosphere composed of an inert gas and oxygen. The process permits a wider selection of Ba raw materials.

High temperature oxide superconductor

A superconductive material is disclosed which has the following composition:

Superconducting material

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Matsudo, Japan

Takayuki Miyatake