Fabrication of large single-domain Sm123 superconductors by OCMG method

Melt processing of Sm-Ba-Cu-O bulk superconductors was studied to find the optimum conditions for fabricating a large single-domain superconductor. First, the holding time at the maximum temperature for the partial melting is important for the fabrication of a uniform bulk, especially for a large diameter. When the holding time at the maximum temperature during partial melting was not enough, two separated regions were observed, which can be diminished by sufficient holding time. Next we studied the optimum conditions for grain growth, varying the temperature gradient and cooling rate. The processing condition with which we have succeeded in growing a single-domain SmBa2Cu3Oy (Sm123 hereafter) with dimensions of 35 φ × 15 mm2 is a temperature gradient of 7.5 °C cm−1 with a slow cooling rate of 0.33 °C h−1.