Novel seed for batch cold seeding production of GdBaCuO bulks

A batch process for fabrication of GdBa₂Cu₃O _y pellets in air was developed. The samples were melt-processed using the cold-seeding method and as seeds Nd-123 thin films grown on MgO crystals. We used a self-made Gd-123 and Gd-211 powders mixed with 0.1 wt.% of Pt. Up to 1-1.5 kg of melt-grown Gd-123 bulks can be prepared in one process. XRD results confirmed that all the bulks are c-axis oriented. The superconducting and magnetic performance of the pellets is checked on several small test samples cut out at various standard positions within the bulk. The values are quite uniform and performance is similar to the oxygen-controlled melt-grown Gd-123 samples. The average trapped field at 77 K in the 24 mm diameter samples batch lies between 0.8 and 0.9 T. The maximum trapped field of 1 T at the sample surface was the highest value 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 scale up from laboratory conditions to industrial production.