${\mathrm{Pb}}_{0.4}$${\mathrm{Bi}}_{1.6}$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_{8+\mathit{x}}$ and oxygen stoichiometry: Structure, resistivity, Fermi-surface topology, and normal-state properties

${\mathrm{Pb}}_{0.4}$ ${\mathrm{Bi}}_{1.6}$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathit{x}}$ [Bi(Pb)-2212] single-crystal samples were studied using transmission electron microscopy (TEM), ab-plane (${\mathrm{\rho }}_{\mathit{a}\mathit{b}}$) and c-axis (${\mathrm{\rho }}_{\mathit{c}}$) resistivity, and high-resolution angle-resolved ultraviolet photoemission spectroscopy (ARUPS). TEM reveals that the modulation in the b axis for Pb(0.4)-doped Bi(Pb)-2212 is dominantly of Pb type that is not sensitive to the oxygen content of the system, and the system clearly shows a structure of orthorhombic symmetry. Oxygen-annealed samples exhibit a much lower c-axis resistivity and a resistivity minimum at 80–130 K. He-annealed samples exhibit a much higher c-axis resistivity and d${\mathrm{\rho }}_{\mathit{c}}$/dT<0 behavior below 300 K. The Fermi surface (FS) of oxygen-annealed Bi(Pb)-2212 mapped out by ARUPS has a pocket in the FS around the M¯ point and exhibits orthorhombic symmetry. There are flat, parallel sections of the FS, about 60% of the maximum possible along ${\mathit{k}}_{\mathit{x}}$=${\mathit{k}}_{\mathit{y}}$, and about 30% along ${\mathit{k}}_{\mathit{x}}$=-${\mathit{k}}_{\mathit{y}}$. The wave vectors connecting the flat sections are about 0.72(π,π) along ${\mathit{k}}_{\mathit{x}}$=${\mathit{k}}_{\mathit{y}}$, and about 0.80(π,π) along ${\mathit{k}}_{\mathit{x}}$=-${\mathit{k}}_{\mathit{y}}$, rather than (π,π). The symmetry of the near-Fermi-energy dispersing states in the normal state changes between oxygen-annealed and He-annealed samples.