Flux pinning and orientation control of large grain LREBa ₂Cu₃O_y

The ternary high-T_c superconductor (Nd_0.33, Eu _0.39, Gd_0.27)Ba₂Cu₃O_y NEG-123 doped by 5 mol% of the nonsuperconducting secondary phase (Nd _0.33, Eu_0.33, Gd_0.33)₂BaCuO ₅ NEG-211 was prepared by oxygen controlled melt growth (OCMG) process using MgO seeds. Various contents of ZnO up to 0.07 mol% were added. At the ZnO concentration around 0.035 mol%, a substantial reduction of liquid phase loss was observed, accompanied with a perfect facet line up to the bottom of the sample, with c-axis reflection plane. Magnetization measurements showed that at this optimum ZnO addition the superconducting transition temperature was slightly depressed. On the other hand, flux pinning performance around the secondary peak, observed at liquid nitrogen temperature, was continually improved with increasing ZnO content up to 0.035 mol%. It was found that the optimum content of ZnO is crucial for flux pining enhancement and orientation control of MgO seeded melt-textured NEG-123 system.