Nippon Steel Corporation

Katsuyoshi Miyamoto

Mitsuru Morita

Kiyoshi Sawano

Masato Murakami

Shoichi Matsuda

Shouichi Matsuda

Keiichi Kimura

Masamoto Tanaka

Seiki Takebayashi

Disclosed is an oxide superconductor comprising an oxide of RE, Ba and Cu, which consists of a superconductor having a texture wherein the crystal directions of the 123 phase in the matrix are uniform, large angle grain boundaries having an directional difference larger than 20.degree. are not present and the 211 phase is finely dispersed, or an aggregate thereof, wherein the superconductor is formed into a plate or wire and the c-axis of the crystal of the formed body is uniform within .+-.30.degree. to the normal of the plate face of the formed body or in the range of from 60.degree. to 120.degree. to said normal. Also disclosed is a process for the preparation of an oxide superconductor as set forth above, which comprises inserting a formed body as mentioned above to a heating furnace and moving a region of a temperature at which grains are formed in the 123 phase of the matrix of the formed body, i.e., through a region having a temperature of from 1050.degree. to 910.degree. C., having a temperature gradient of at least 2.degree. C./cm, at a speed lower than 0.4 cm/hr from the top end of the formed body to the rear and thereof.

1-2-3 single crystal oxide superconductor containing 211 phase and

The present invention is characterized in that oxides of Y, Ba and Cu having a superconductive substance-forming composition are melted, the melt is rapidly cooled and solidified, the obtained sheet is heated at a temperature of 1000.degree. to 1350.degree. C. to produce a partially melted state thereof, and the sheet is gradually cooled at a rate lower than 200.degree. C./hr, whereby a micro-structure in which precipitates of the RE.sub.2 BaCuO.sub.5 phase having a diameter smaller than 20 .mu.m are dispersed in the REBa.sub.2 Cu.sub.3 O.sub.7-y crystal is obtained.

REBa.sub.2 Cu.sub.3 O.sub.7-y type oxide superconductive material having

Oxide superconductor and process for preparation thereof

YBa.sub.2 Cu.sub.3 O.sub.7-y type oxide superconductive material

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Kawasaki, Japan

Katsuyoshi Miyamoto