Metallic, but not superconducting, La-Ba (and La-Sr) copper oxides

New measurements are reported on three La-Ba (and La-Sr) copper-oxide compounds, including one new compound. These materials have metallic conductivities, comparable to those of the high-Tc copper oxides in the normal state, but they are not superconducting down to 5 K. Their magnetic susceptibility and structural features are also similar. These data provide a new challenge and test for the numerous theories of high Tc to account also for its absence in these three closely related materials. © 1988 The American Physical Society.