Magnetic Field Dependence of Jc in A T1–1223 Wire; Presence of Pinning and Good Grain Boundary Connectivity.

ABSTRACTThe existence of effective pinning in single T1-layer 1223 superconductors has been reported [1–3], as opposed to lower values in T1- and Bi-double layer systems, which is intimately related to their crystal structures. In order to investigate the possibility of T1–1223 being applied as a practical superconductor, tape shaped wires of the chemical composition (T10.5Pb0.51 (Sr0.8Ba0.2Ca2Cu3O9were prepared. Transport Jc of T1–1223 was measured to be 1.8 × 104 A/cm2 at 77K in the absence of a magnetic field. These results seem to imply that T1–1223 has, not only effective pinning because of having a more 3-dimensional vortex line lattice like YBa2Cu3O7, but also better grain boundary weak-link performance than YBa2Cu3O7. PresenT1y it appears that T1–1223 may be a superior choice to make better superconducting wire, because of these considerations and of the higher Tc of 120K.(T10.5Pb0.5)1Sr2CaCu2O7 (T1–1212) also seems to have effective pinning, as well as T1–1223, supporting the idea that shorter Cu-O plane spacing, or absence of thicker insulating region such as T12O2 or Bi2O2 double layer, are beneficial for effective pinning through facilitating a better 3D-like vortex line lattice [4, 5]. Our “1212” and “1223” samples are good counter examples to the 2D pancake-like vortex theory [6, 7].