Effect of Zr addition on the field dependence of transport Jc for filamentary (Nd0.33Eu0.38Gd0.28)Ba2Cu3Ox superconductors

We have studied the effect of Zr addition on the field dependence of transport J_c for filamentary (Nd-Eu-Gd)Ba₂Cu₃O_x superconductors to enhance the flux pinning. We prepared the filamentary (Nd_0.33Eu_0.38Gd_0.28)Ba₂Cu₃O_xZr_y (y=0, 0.001, 0.002) precursors by a solution spinning method. The precursor was partially melted in flowing 0.1%O₂+Ar under various heating conditions to obtain high J_c value. The optimum heating condition was dependent on sample diameter. A maximum J_c value of 3×10⁴ A/cm² at 77 K and self-field was attained for the sample with 0.001 at% Zr. The samples had well aligned texture along the filament diameter as well as the length. The J_c was measured at 77 K in applied magnetic fields up to 14 T by rotating the sample along the direction perpendicular to the filament length. Anisotropic behavior of the field dependence of J_c was detected. Although the J_c values measured at the optimum angle for the samples with 0.001 at% Zr decreased with increasing the applied fields above 10 T, the J_c values for the Zr addition samples were higher than that for the non addition sample by applying the fields up to 11 T.