Preparation of Dy-123 system superconductor composed with Pt–Rh wires

Abstract

The melt-textured DyBa 2Cu 3O x (Dy-123) system superconductors were grown by means of the top seeding and temperature gradient method. Ag 2O powder of 30 wt% was added to the mixture of Dy-123 and Dy-211 powder. The pellet of 20 mm in diameter and 20 mm in thickness was prepared using coaxial pressing equipment. For improving the mechanical property and resolving the hot-spot problem, platinum–rhodium (Pt–Rh) alloy wires 0.4 mm in diameter and 18 mm in length were added from the surface into the bottom of the pellet. The pellet was partially melted in air at 1030 °C for one hr and rapidly cooled to 975 °C in a bulk material, where Nd-123 seed crystal was placed in contact with the top surface of the bulk. After the seeding, the bulk was cooled to 925 °C, and then furnace-cooled to the room temperature. Finally, the sample was annealed in oxygen atmosphere. The single-domain superconducting bulk containing two Pt–Rh wires was fabricated. There were intermediate layers and no voids or cracks between the metal wire and Dy-123 superconducting oxide. Single peak in the trapped field distribution with the maximum value of about 0.12 T at 77.3 K was obtained, which was almost the same as that of the bulk without wires. It was concluded that the superconductivity of the melt textured bulk was not deteriorated by the addition of Pt–Rh wires.