Processing and Applications of Bulk RE–Ba–Cu–O Superconductors

I will summarize the current status of processing and applications of bulk high‐temperature RE–Ba–Cu–O (RE: rare‐earth elements) superconductors. Recent advancement of processing techniques led to the production of single‐grain RE–Ba–Cu–O superconductors >10 cm in diameter. The maximum‐trapped field values of single‐grain RE–Ba–Cu–O are 4 T at 77 K, 9 T at 46 K, and 17 T at 29 K. The mechanical properties as well as thermal stability were greatly improved through impregnation of metals and resin, which is highly important for practical engineering applications. Industrial applications of bulk RE–Ba–Cu–O can be categorized into three major regions: levitation, trapped field magnets, and conductors. Stable levitation without active control has been used for non‐contact bearings of a flywheel energy storage system, levitated vehicles, and non‐contact mixers. Trapped field magnets are used for a field generator, a magnetic separator for water purification, a magnetron‐sputtering device, a nuclear magnetic resonance spectrometer, and an undulator. Bulk RE–Ba–Cu–O is also used as conductors like current leads and resistive fault current limiters.