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.