Welding of Y-Ba-Cu-O Bulk Superconductors Using Superconducting Er-Ba-Cu-O Solder

We have succeeded in producing a strongly coupled superconducting Y-Ba-Cu-O joint by combining the control of crystal growth along the ‹110› direction and employment of a highly dense Er-Ba-Cu-O sintered solder. No segregation of the secondary phase and residual liquid phase was observed at the joint, which led to the formation of a strongly connected superconducting joint. Microstructural observation showed that many triangular crystals grew from the mother block in the (110)/(110)-joint, while the growth front was parallel to the (100) surfaces in the (100)/(100)-joint. Such a discrepancy was ascribed to the difference in the superconducting properties of the joints.