摘要
It is well known that in the Bi-series superconductors, low temperature phases, such as 2201, 2212 phases, always coexist with 2223 phase to some extent, which makes it difficult to prepare high-T_c 2223 phase samples. Doping of Pb and F can help the forming of 2223 phase and the superconductors with zero resistance temperature 107 K and 118 K can be obtained. But so far most experimental results have pointed out that it is difficult to
