HIGH J(C) YBCO CURRENT LEAD BY UNIDIRECTIONAL SOLIDIFICATION

The unidirectional solidification method was used in order to synthesi ze current leads of high J(c) by different traveling rates for differe nt initial compositions of YBa2Cu3O6+delta (Y123) + x% Y2BaCuO5 (Y211) (x = 10, 20, 30, 40 and 50) with the addition of 0.5 wt.% Pt. The hig hest J(c) was found in the sample with 30% excess Y211 in the initial composition by the higher traveling rate, namely 3 mm h(-1), adjusted to prevent the formation of polycrystals. In this 1.56 mn x 60 mm samp le the values of transport I-c and J(c) were 1370 A and 71700 A cm(-2) , respectively, which were obtained by the conventional DC four-probe method with criterion of 1 mu V cm(-1) at 77 K and self-field. (C) 199 8 Elsevier Science S.A. All rights reserved.