Characteristics of metal impregnated bulk Gd-Ba-Cu-O superconductors cooled down in a magnetic field

Gd-Ba-Cu-O bulk superconductors have significant potential for various applications due to their high critical current density and high trapped magnetic field. We investigated the mechanical properties and cryostability of a Gd-Ba-Cu-O bulk superconductor. Increasing the toughness of the bulk and improvement of the heat conduction are both important for enhancing the trapped magnetic field. We introduced a stainless steel ring around the circumference of the bulk to increase the strength of the bulk. Also, we introduced Al wires inserted in the holes along the c-axis of the bulk, after which the sample was impregnated with Bi-Sn-Cd alloy. At T ≤ 77 K, starting from B ≤ 3 T, the 14 mm thick and 44 mm diameter samples were able to trap a flux density of 1.13-1.36 T. The repulsive force between the superconductor sample bulk and a permanent magnet with a surface magnetic induction of 0.37 T was about 70 N for a 1 mm gap. We also measured the temperature rise of the bulk superconductor surface, at various temperatures, when the external field went down from B ≤ 9 to 0 T.