Large Size and High Performance of a Gd-Ba-Cu-O Bulk Superconductor Grown Using New Approaches.

In this study, we report new approaches for the fabrication of Gd-Ba-Cu-O (GdBCO) bulk with a large size and promising superconducting properties, applying the cold-seeding melt-textured (MT) method. Firstly, NdBCO thin films were used as seeds because of their superheating properties and an additional mini pellet was inserted between the seed and the bulk precursor. This approach allows to reach a higher maximum processing temperature ( Tmax) and a wider window for single grain growth, leading to the growth of large-sized bulk, 56 mm in diameter. Secondly, the use of both air and pure oxygen atmosphere in the growth process of GdBCO bulks indicates that high oxygen partial pressure has little impact on superconducting properties, which, however, effectively facilitates the growth rate. Thus, an oxygen-rich MT process is promisingly suggested for producing large-sized GdBCO bulks with insignificant degradation of superconducting properties. Finally, a new Ba-rich precursor was applied by adding an Sm242 compound. It was deduced that the addition of a substantial amount of Sm242 may enhance the critical current density Jc with an insignificant reduction of Tc. [ABSTRACT FROM AUTHOR]