Fabrication of Bi-Sr-Ca-Cu oxide superconductors with controlled numbers of Cu-O layers

Since the discovery of multiphase Bi-Sr- Ca-Cu-O superconductors, it becomes soon clear that these phases can be distinguished by the number of CuO layers, n, sandwiched by two BiO double layers. Thus the chemical compositions of these compounds are Bi2Sr2Can-1CunO2n+4 (n = 1-3) thereafter these phases are abbreviated as the 22(n - 1)n phase. The correlation between the superconducting transition temperature, Tc, and the number of CuO layers, n, is also established, i.e., Tc increases with increasing n from 1 to 3 as 8, 80 and 107 K, respectively. Although Tc varies significantly with the small variation of each component within the solid-solubility range, much effort has been extended to increase the volume fraction of the n = 3 phase, i.e., the 2223 phase