Abstract
Bulk superconductivity with T c (zero) up to 95 K in a Tl 0.5 Pb 0.5 Ca 0.9 Ce 0.1 Sr 2 Cu 2 oxide with an Y 1 Ba 2 Cu 3 O y -like structure was observed. Single-phase samples, tetragonal in structure with a=0.380±0.001, c=1.195±0.001 nm, and of P4/mmm space group, were prepared. The results represent the first case where Ce substitution significantly raised the T c of a known compound. The samples were remarkably homogeneous both in composition and structure. The compounds were highly reproducible and stable. The preparative conditions were found to be much less stringent than those of other copper-based high T c superconductors.