Buffer-Assisted Top-Seeded Infiltration and Growth for Fabricating Dense, Single-Grain (RE)-Ba-Cu-O Bulk Superconductors
(RE)BCO, rare-earth based high temperature superconductors fabricated in the form of large, single grain bulk samples can trap comparatively large magnetic fields in relatively small sample volumes, unlike conventional permanent magnetic materials. Fabrication of (RE)BCO single grains has been achieved largely following the development of processing techniques based on melt growth (MG). In the present study, the recently developed alternative fabrication technique of infiltration and growth (IG) is discussed and its significance highlighted in the context of obtaining (RE)BCO bulk superconductors with dense microstructures. The necessity of employing a buffer layer in the IG methodology is elucidated. The path followed in solving the complex problem of controlling the amount of RE2BaCuO5 (RE-211) present in the microstructure of the end product to achieve enhanced and optimized flux pinning is described. A brief overview of the recently developed 2-step, buffer-assisted top-seeded infiltration and growth (BA-TSIG) fabrication technique, which enables successful fabrication of (RE)BCO bulks, is presented. Finally, two novel experiments based on the TSIG technique – fabrication of a bar-shaped YBCO sample (with size: 72 mm x 24 mm x 15 mm) and multi-seeding of YBCO (with two NdBCO seeds in 0°-0° configuration, with aligned a-b planes) – are described and further potential options for the fabrication of complex-shaped (RE)BCO bulk components for specific practical applications are outlined.