Improvement of Electromagnetic Properties of Ag-clad Bi-Based Superconducting Tapes Through Process Control

摘要

Improvement of critical current density of the Ag-clad Bi-based superconducting tapes have been recently achieved through control of initial phase composition, formation of high Tc phase and melting in varying atmosphere. The amount of Ca_2PbO_4 in the precursor powder was found to have a significant effect on sintering temperature and time. Incorporation of Ca_2PbO_4 into Bi_2Sr_2CaCu_2O_8+x(2212) phase can reduce the duration fo (Bi,Pb)_2Sr_2Ca_2Cu_3O_10-x (2223) tape process to below 100h. The irreversibility line for the 2212 tape is positioned at higher temperatures than those for the 2212 crystals. The intragranular current declines with increasing magnetic field more rapidly than intergranular current at high temperatures, suggesting that the flux creep controls the critical current at high temperatures.