| 摘要 |
<p>A method for making a rare earth superconductive composite including a matrix of REBa2 CU3 O7-x grains and, uniformly dispersed therein, fine particles of RE2BaCuO5, 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, includes the steps of: (1) forming a compacted mass by application of pressure out of a powder material including REBa2 Cu3 O7-x and RE2BaCuO5 in a powder form wherein powder particles of REBa2 CU3 O7-x have an average diameter up to 6 mu m and a maximum diameter up to 20 mu m, and powder particles of RE2BaCuO5 have an average diameter up to 6 mu m and a maximum diameter up to 20 mu m; (2) heating the compacted mass to a temperature which is higher than an incongruent melting temperature of REBa2 CU3 O7-x and which is lower than an incongruent melting temperature of RE2BaCuO5 so as to partially melt and decompose the REBa2 CU3 O7-x in the mass into a melt and RE2BaCuO5 in a solid state; (3) gradually cooling the mass so as to recrystallizes REBa2Cu3 O7-x from the melt wherein fine particles of RE2BaCuO5 are dispersed in grains of REBa2 CU3 O7-x; and (4) annealing the mass in an atmosphere containing oxygen for a time sufficient for the requisite amount of oxygen to diffuse into the mass. Fine particles of RE2BaCuO5 in the composite have a diameter up to 20 mu m, and and work as pinning centers. The small powder particles of REBa2 Cu3 O7-x and RE2BaCuO5 in the compacted mass makes RE2BaCuO5 particles dispersed in the resulting composite smaller thereby improving critical current density of the composite.</p> |
