Synthesis, characterization and melt processing of Y_1-x(Yb_0.9Nd_0.1)_x Ba₂Cu₃O_z superconductors

Effects of a combined substitute of Yb and Nd on Y site on the superconducting properties of YBa₂Cu₃O_y have been studied. We synthesized Y_1-x(Yb_0.9Nd_0.1)_x Ba₂Cu₃O_z compound with x = 0.2, 0.4, 0.6, 0.8 and 1.0. Here, the ratio of Yb-Nd was fixed to be 9:1 for obtaining 123 phase without secondary phases. The melt processing thermal profiles for Y_1-x(Yb_0.9Nd_0.1)_x Ba₂Cu₃O_z with x = 0.2 and 0.4 and the addition of 40 mol% {Y_1-x(Yb_0.9Nd_0.1) _x}₂BaCuO₅ and 0.5 wt% Pt in air were determined onthe basis of the thermal analysis results. All samples showed a low grain growth rate, particularly for high x values, which may be partially ascribed to un-optimized thermal schedules. Although almost all the samples exhibited low J_c values, the sample with x = 0.2 exhibited T_c of 88.8 K and a relatively high J_c value of 16,000 A/cm ² at 77 K for H//c-axis.