Properties of Bi(Pb)-2223 precursor powders calcined in reduced oxygen partial pressure
The performance of Ag/Bi-2223 superconducting tapes is affected by complex processing parameters, especially by the characteristics of the precursor powder, i.e., the nominal stoichiometry, phase assemblage, purity, particle size and distribution, etc. Calcination in a low oxygen partial pressure (3 torr oxygen) resulted in a reactive precursor powder by the accelerated decomposition of the carbonates. In addition, the type of second phase and the distribution of lead in this precursor powder are different compared to those of the powder calcined in atmospheric air. Ag/Bi-2223 tapes have been fabricated and the phase evolution, critical current density, and microstructure of the two tapes have been compared.