A Reliable Method for Recycling (RE)‐Ba‐Cu‐O (RE: Sm, Gd, Y) Bulk Superconductors

Abstract

Single grain (RE)-Ba-Cu-O (RE: Sm, Gd, Y) high-temperature superconductors are able to generate high magnetic fields. However, the relatively high cost of the raw materials and the low yield of the manufacturing process have impeded the development of practical applications of these materials to date. This article describes a simple, reliable, and economical method of recycling failed bulk (RE)-Ba-Cu-O (RE: Sm, Gd, Y) samples. Sixty-four failed bulk samples, with diameters up to 31 mm, were recycled with a yield of 90%. The key innovation in this recycling process involves reintroducing the liquid phase into the melt process, which is normally lost during the primary peritectic processing of these materials. This enables the direct re-growth of failed samples from solid form without the need for re-grinding into powder. We also demonstrate that the superconducting performance and microstructure of the recycled samples is similar to that of the primary grown samples.

Microstructure and Composition of Primary and Recycled Single Grains of YBCO, GdBCO‐Ag, and SmBCO‐Ag Bulk Superconductors

“…The average value of J c is very different for the two recycled samples and for the recycled and primary grown samples for the SmBCO‐Ag system. The reduction in T c and J c (0) for recycled samples in comparison to primary grown samples is in agreement with previous results …”

“…, with typical values of maximum trapped field for the recycled samples given in Table . These values are similar to those measured previously for recycled samples . It can be concluded that the recycled samples typically exhibit a maximum trapped field of approximately 15% lower than primary grown samples which is in agreement with previous results …”

“…The failed samples for recycling were prepared as reported elsewhere . A single crystal seed was placed centrally on top of a precursor buffer pellet of the appropriate composition for the growth of a single grain .…”

“…A technique to recycle failed single grains has been developed by the Cambridge Bulk Superconductivity Group that is both cheap and easy to apply, and which has been found to be reliable in the fabrication of complete single grains . The reasons for the success of the recycling technique are not clear, however, so we have repeated systematically the recycling process for the YBCO, GdBCO‐Ag, and SmBCO‐Ag systems.…”

Towards a sustainable fabrication of cryomagnets: Melting‐driving approaches for recycling failed REBa2Cu3Ox bulks

“…Based on the current top‐seeded melt‐growth (TSMG) technique with the use of high thermal stability film, RE123 bulks can be batch‐produced for meeting the application requirements. However, factors like temperature fluctuation inside furnace, wrong orientation of the seed, and a nonoptimized process give rise to a high growth failure rate of approximately 20%, since these failed bulks contain expensive matters, such as Ag, Pt, and RE, various recycling processes were developed to regrow them …”