Bulk superconductivity above 30 K inT/emph>-phase compounds

High-pressure (3 kbar) oxygenation of (La, Sm, Sr${)}_2$ ${\mathrm{CuO}}_4$ compounds having the $T^{\mathrm{*}}$ structure leads to bulk superconducting transitions above 30 K and the appearance of a diamagnetic response at temperatures as high as ∼37 K. With increasing oxygenation pressure, the electrical resistivity and thermoelectric power progress from hoppinglike to more nearly metalliclike transport. The similarity in $T_c$ and transport character with those of T-phase ${\mathrm{La}}_{2\mathrm{-}\mathrm{x}}$ ${\mathrm{Sr}}_{\mathrm{x}}$ ${\mathrm{CuO}}_4$, despite significant structural differences, further constrains possible mechanisms for superconductivity in the cuprates.