Overdoped metals in the Tl[sub 2]Ba[sub 2]CuO[sub 6+[delta]] and TlSr[sub 2]CaCu[sub 2]O[sub 7[minus][delta]] systems

We have synthesized overdoped metallic samples of Tl[sub 2]Ba[sub 2]CuO[sub 6+[delta]] and TlSr[sub 2]CaCu[sub 2]O[sub 7[minus][delta]] beyond the superconductor-metal phase boundary by annealing the samples in high-pressure oxygen. Oxygen incorporation is clearly demonstrated by structural refinements of neutron powder-diffraction data and reversible changes in sample weight. The same [similar to][ital T][sup 2] scattering mechanism in transport properties as previously observed in superconducting samples is observed in the present overdoped metallic samples. Hall coefficients do not change sign and are still positive for the overdoped metals. Although the crystal structures of both compounds change gradually and continuously with oxygen doping beyond the superconductor-metal phase boundary, the electronic structure of the further overdoped metals'' might still be near the supeconductor-metal phase boundary.