A low-cost batch process for high-performance melt-textured GdBaCuO pellets

High-T_c superconducting magnets promise a variety of industrial, medical, public, and research applications. However, the potential large-scale applications of these materials need excellent and uniform properties and a cheap production method. The batch process developed for the fabrication of GdBa₂Cu₃O_y pellets in air fulfils all of these requirements. The samples were melt-processed using a cold seeding method with thin film Nd-123 seeds grown on MgO crystals. We used self-made Gd-123 and Gd-211 powders mixed with 0.1wt% of Pt. Up to 1-1.5kg of melt-grown Gd-123 bulks could be prepared in one run. XRD analysis confirmed that all of the bulks were c-axis oriented. The superconducting and magnetic performance of the pellets was checked on several small test samples cut out at various standard positions within the bulk. The values were reasonably uniform and the performance was similar to the oxygen-controlled melt-grown Gd-123 samples. The average trapped field at 77K in the 24mm diameter batch samples was between 0.8 and 0.9T, close to the maximum value of 1T reported so far for Gd-123 single grains processed in air. The present results prove that a high-performance good-quality LREBa ₂Cu₃O_y material can be scaled up from laboratory to industrial production.