US 5,496,799 AGranted

Method for making rare earth superconductive composite

AssigneesNGK Insulators, Ltd., International Superconductivity Technology Center

InventorsManabu Yoshida, Izumi Hirabayashi

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Abstract

A method for making a rare earth superconductive composite which includes a matrix of REBa.sub.2 Cu.sub.3 O.sub.7-x grains and fine particles of RE.sub.2 BaCuO.sub.5 dispersed therein. The method includes a step of forming a compacted mass of powder particles of REBa.sub.2 Cu.sub.3 O.sub.7-x and powder particles of RE.sub.2 BaCuO.sub.5, each of which has an average diameter not greater than 6 .mu.m, and a maximum diameter not greater than 20 .mu.m. The compacted mass is heated to temperature higher than an incongruent melting temperature of the REBa.sub.2 Cu.sub.3 O.sub.7-x and lower than an incongruent melting temperature of RE.sub.2 BaCuO.sub.5, and is gradually cooled such that fine particles of RE.sub.2 BaCuO.sub.5 are dispersed in REBa.sub.2 Cu.sub.3 O.sub.7-x grains. The mass is annealed in an atmosphere containing oxygen.

Claims12

Dependent claims

A method for making a rare earth superconductive composite including a matrix of REBa.sub.2 Cu.sub.3 O.sub.7-x grains and, uniformly dispersed therein, fine particles of RE.sub.2 BaCuO.sub.5, wherein RE is at least one element selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu, and x ranges from 0 to 1, said rare earth superconductive composite having a critical current density of not less than 17,000 A/cm.sup.2 at 77K under one tesla, which comprises the steps of:

(1) forming a compacted mass by application of pressure to a powder material including powder particles of REBa.sub.2 Cu.sub.3 O.sub.7-x and powder particles of RE.sub.2 BaCuO.sub.5 wherein said powder particles of REBa.sub.2 Cu.sub.3 O.sub.7-x have an average diameter not greater than 6 .mu.m and a maximum diameter not greater than 20 .mu.m, and said powder particles of RE.sub.2 BaCuO.sub.5 have an average diameter not greater than 6 .mu.m and a maximum diameter not greater than 20 .mu.m;
(2) heating the compacted mass to a temperature which is higher than an incongruent melting temperature of REBa.sub.2 Cu.sub.3 O.sub.7-x and which is lower than an incongruent melting temperature of RE.sub.2 BaCuO.sub.5 so as to partially melt and decompose the REBa.sub.2 Cu.sub.3 O.sub.7-x in the mass into a melt and to maintain the RE.sub.2 BaCuO.sub.5 in a solid state;
(3) gradually cooling the mass from an initial temperature so as to recrystallize REBa.sub.2 Cu.sub.3 O.sub.7-x from the melt wherein fine particles of RE.sub.2 BaCuO.sub.5 are dispersed in REBa.sub.2 Cu.sub.3 O.sub.7-x grains, wherein the melt contains a species to aid in dispersion of the RE.sub.2 BaCuO.sub.5, said species comprising at least one element selected from the group consisting of Pt, Rh, Pd, Ru, Os and Sc, said melt containing 0.01% to 10% by weight, with respect to the sum of RE.sub.2 BaCuO.sub.5 and REBa.sub.2 CuO.sub.7-x, of said species;
and
(4) annealing the mass in an atmosphere containing oxygen for a time sufficient for a requisite amount of oxygen to diffuse into the mass.

2 more elements

(1) forming a compacted mass by application of pressure to a powder material including powder particles of REBa.sub.2 Cu.sub.3 O.sub.7-x and powder particles of RE.sub.2 BaCuO.sub.5 wherein said powder particles of REBa.sub.2 Cu.sub.3 O.sub.7-x have an average diameter not greater than 6 .mu.m and a maximum diameter not greater than 20 .mu.m, and said powder particles of RE.sub.2 BaCuO.sub.5 have an average diameter not greater than 6 .mu.m and a maximum diameter not greater than 20 .mu.m;
(2) heating the compacted mass to a temperature which is higher than an incongruent melting temperature of REBa.sub.2 Cu.sub.3 O.sub.7-x and which is lower than an incongruent melting temperature of RE.sub.2 BaCuO.sub.5 so as to partially melt and decompose the REBa.sub.2 Cu.sub.3 O.sub.7-x in the mass into a melt and to maintain the RE.sub.2 BaCuO.sub.5 in a solid state;
(3) gradually cooling the mass from an initial temperature so as to recrystallize REBa.sub.2 Cu.sub.3 O.sub.7-x from the melt wherein fine particles of RE.sub.2 BaCuO.sub.5 are dispersed in REBa.sub.2 Cu.sub.3 O.sub.7-x grains, wherein the melt contains a species to aid in dispersion of the RE.sub.2 BaCuO.sub.5, said species comprising at least one element selected from the group consisting of Pt, Rh, Pd, Ru, Os and Sc, said melt containing 0.01% to 10% by weight, with respect to the sum of RE.sub.2 BaCuO.sub.5 and REBa.sub.2 CuO.sub.7-x, of said species;
and
(4) annealing the mass in an atmosphere containing oxygen for a time sufficient for a requisite amount of oxygen to diffuse into the mass.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/366,384Filed 29 Dec 1994 · continuation
Priority: JP 4-22603325 Aug 1992
Granted: 5 Mar 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

C04B 35/4508
Containing rare earth oxides: type 1-2-3
C04B 35/653
Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products: processes involving a melting step
H10N 60/0828
Of devices comprising copper oxide: introducing flux pinning centres
C04B
Lime, magnesia