Trapped fields beyond 14 Tesla in bulk YBa2CU3O7-delta

Bulk YBa2Cu3O7-delta material with single-domain grains up to 35 mm in diam eter was prepared by a modified melt-texturing process. The pinning propert ies were improved by chemical doping of Zn on Cu plane sites resulting in a well pronounced peak effect in the field dependence of the critical curren t density. Trapped fields of more than 1.1 T at 77 K have been obtained in a zinc-doped YBCO disk of only 27 mm in diameter. Higher trapped fields are observed at lower temperatures due to the increasing critical current dens ity, however, at temperatures between 50 and 20 K, the trapped field is lim ited by the mechanical properties. Using a bandage made of steel, very high trapped fields were achieved in the 1 mm gap between two YBCO disks, Trapp ed fields up to 14.4 T were found at 22.5K in such minimagnets containing s ilver precipitates, whereas the trapped fields of zinc-doped minimagnets re ached values of 11.2 T at 47 K.