Variable normal-state transport properties of ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_{8\mathrm{-}\mathrm{y}}$

The normal-state thermoelectric power S and resistivity ρ of crystalline ${\mathrm{Bi}}_2$ ${\mathrm{Sr}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8\mathrm{-}\mathrm{y}}$ are strongly influenced by oxygen configuration. In general, the temperature dependences of the coefficients follow simple empirical expressions. For the ab-plane and c-axis thermopower, S∼A+BT, while for the ab-plane resistivity, ρ∼$T^{\alpha }$ exp[Δ/$k_B$T]. Only A and Δ depend on oxygen configuration. These expressions may hold also for other classes of high-$T_c$ superconducting oxides and are suggestive of and place restrictions on normal-state transport models; normal-state transport models should in turn relate to superconductivity mechanisms.