Trapped field in large single-domain Dy-123 system superconductor

Since melt-textured RE-system bulk can trap strong magnetic flux, it acts as a quasi-permanent magnet stronger than conventional permanent magnets. Large single domain Dy-123 system superconductors about 48 mm in diameter and 15 mm in thickness were prepared with a seeding and temperature gradient method in air. DyBa2Cu3Ox (Dy-123) and Dy2BaCuOy (Dy-211) powders were mixed in molar ratios of 1:0.3. Ag2O of 10 wt% and Pt of 0.5 wt% were added to the mixture. The pellets were partially melted at 1070 degrees C for 4 hour, and rapidly cooled to 980 degrees C for one hour. When the top temperature of the sample reached 980 degrees C, the ab-plane of Nd-123 seed crystal was placed in contact with the top surface of the bulk. After the seeding, the samples were cooled to 930 degrees C with a cooling rate of 0.07-0.08 degrees C/hr, and then the bulks were cooled to room temperature with furnace cooling. Finally, the samples were annealed in pure oxygen atmosphere from 500 degrees C to 250 degrees C for 500 hours. Two samples of the melt-textured single domain were fabricated. Homogeneous morphology was obtained in the samples. When magnetic field of 1.5 T was applied for the samples, about 0.7 T was trapped at 77.3 K.