The effects of the pulling rate and Ag addition on the properties of Sm123 rods fabricated by the directional solidification method

The effects of the pulling rate and Ag addition on superconducting properties were investigated for Sm123 samples fabricated by the directional solidification method in air. The critical temperature (T-c) value of Sm123 without Ag annealed only at 300 degrees C depended on the pulling rate; a high pulling rate resulted in a high Tc value. When the samples were heated at 900 degrees C before being annealed at 300. C, the Tc values were increased compared to those annealed at only 300. C. These results suggest that the composition of Sm123 was affected by the pulling rate; an Sm atom tended to substitute for a Ba site in the sample pulled at a slow rate. On the other hand, the Sm123 with Ag showed a Tc value of 93 K, irrespective of the pulling rate and the annealing patterns. This means that Sm/Ba substitution could be suppressed enough by the addition of Ag. An I-c value higher than 900 A was achieved in an Sm123 rod with a diameter of 2 mm with Ag addition. The addition of Ag for Sm123 is effective for achieving high superconducting properties through the suppression of Sm/Ba substitution, as well as for improving the mechanical properties.