Modulation-free bismuth-lead cuprate superconductors: ${\mathrm{BiPbSr}}_{1+\mathit{x}}$${\mathit{L}}_{1\mathrm{-}\mathit{x}}$${\mathrm{CuO}}_6$ and ${\mathrm{BiPbSr}}_2$${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{Cu}}_2$${\mathrm{O}}_8$

Modulation-free BiPbSrL${\mathrm{CuO}}_6$ (L=La, Pr, Nd) and ${\mathrm{BiPbSr}}_2$${\mathrm{YCu}}_2$${\mathrm{O}}_8$, which are isotypic with the n=1 and 2 members of the ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{Ca}}_{\mathit{n}\mathrm{-}1}$${\mathrm{Cu}}_{\mathit{n}}$${\mathrm{O}}_{2\mathit{n}+4\mathrm{}}$ family, have been prepared and characterized. These parent compounds are nonsuperconducting, but when doped with holes by substitution chemistry give modulation-free superconducting cuprates of the general formulas ${\mathrm{BiPbSr}}_{1+\mathit{x}}$${\mathit{L}}_{1\mathrm{-}\mathit{x}}$${\mathrm{CuO}}_6$ and ${\mathrm{BiPbSr}}_2$${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{Cu}}_2$${\mathrm{O}}_8$, exhibiting maximum ${\mathit{T}}_{\mathit{c}}$’s of 24 and 85 K, respectively. Significantly, the hole concentration at the maximum ${\mathit{T}}_{\mathit{c}}$ is 0.12 in the cuprate family with a single Cu-O layer and 0.22 in that with two Cu-O layers.