Flux pinning properties of Gd–Ba–Cu–O trapped field magnets grown by a modified top-seeded melt growth

Abstract

We report a modified top-seeded melt-growth technology for processing high performance Gd–Ba–Cu–O trapped field magnets (TFMs) by providing an additional liquid source during the melt-textured growth. The enriched liquid source allows sufficient growth in the a−b plane with an increased growth rate, and depresses the accumulation of Gd2BaCuO5 (Gd211) particles, which largely suppresses the formation of sub-grain boundaries in the a-growth sectors. An average trapped magnet field of 1.2 T is achieved for the 32 mm Gd–Ba–Cu–O TFMs at 77 K. These Gd–Bd–Cu–O TFMs exhibit superior in-field flux trapping performance, thanks to the significant second peak effect of the critical current density (Jc). The additional liquid source intensifies the Gd–Ba substitution, and therefore increases the in-field Jc, especially at the temperature range of 30–70 K, which is meaningful for practical applications.