Field trapping property of Gd–Ba–Cu–O bulk superconductor 140 mm in diameter

We have studied field trapping ability of single grain Gd–Ba–Cu–O bulk superconductor 140 mm in diameter, which was fabricated by using Gd2BaO4 and Ba–Cu–O phase as raw materials. The distribution of the trapped magnetic field showed single domain without serious weak links, when the bulk was field-cooled in 1 T at liquid nitrogen temperature. The maximum trapped magnetic field at 77 K and 65 K were 2.30 T and 3.66 T respectively, when a field of 4 T was applied. From the distribution measurements of magnetic field, it was confirmed that a large amount of flux can be trapped in this large bulk. It was also confirmed that magnetic field can reach a longer distance in a larger bulk than smaller diameter samples.