Bulk superconducting magnets with fields beyond 14T

Bulk YBa2Cu3O7-x (YBCO) material with single-domain grains up to 35 mm in d iameter was prepared by a modified melt-texturing process. A maximum trappe d field, B-0, up to 1.1 T at 77 K was obtained on the top of a single YBCO disk 35 mm in diameter by chemical doping of Zn on Cu plane sites increasin g up to 9 T at 43 K due to the increasing critical current density at lower temperatures, At temperatures around 50 K, the trapped field is limited by the mechanical properties and cracking of the material which is exposed to considerable tensile stresses due to Lorentz forces acting during the magn etization procedure on the superconductor. Very high trapped fields up to 1 4.4 T were achieved at 22 K in the gap between two YBCO disks by the additi on of silver improving the fracture toughness of the material and by using a bandage made of steel. This is the highest trapped field achieved so far in a bulk superconductor. On the rop of a single YBCO disk, a maximum trapp ed field of 11.5T was obtained at 17K, In order to use superconducting YBCO permanent magnets in superconducting magnetic bearings, an effective metho d for magnetizing the superconductor is required. Results of magnetizing YB CO samples by applying pulsed magnetic fields will be presented. (C) 2001 E lsevier Science B.V. All rights reserved.