High trapped fields in bulk YBa2Cu3O7-delta samples at temperatures around 50 K

Bulk melt textured YBa2Cu3O7-delta samples with single grains of about 24 mm diameter were obtained by use of SmBa2Cu3O7-x seed crystals. The maximum trapped field B-0 in the gap between two samples was investigated as function of temperature. B-0 increased from 1 T at 77 K to 8.5 T at 51.5 K, which is the highest trapped field achieved in nonirradiated samples. At low temperatures, cracking of the samples was observed under magnetic pressure. In this temperature range, the trapped field is limited by the mechanical strength of the samples, for which a value of 25 MPa was estimated. (C) 1997 American Institute of Physics.