Effect of ZrO₂ and ZnO nanoparticles inclusions on superconductive properties of the melt-processed GdBa₂Cu₃O_7-δ bulk superconductor

Single domain Gd123 bulk superconductors have been fabricated successfully with doping both ZrO₂ and ZnO nanoparticles by a hot seeded melt growth in air. Superconductive properties were studied on the specimens selected from different positions of the domain separately, along the a-b plane and c-axis. The nanosized defects induced by the nanoparticles can be effective pinning center to enhance the J_c of the bulk. Atomic substitution of Cu site with Zn ion enables us to enhance the J_c but the substitution suppresses the T_c of the bulk. By the analysis of the pinning force, for the specimens cut along the a-b plane, the δl pinning is enhanced by the addition of nanoparticles. While for the specimens cut along the c-axis, the δT_c pinning is remarkably enhanced.