Superconductivity in the Tl-Nd-Sr-Cu-O and the Tl-Pb-Nd-Sr-Cu-O systems.

We report the evidence for superconductivity in the Tl-Nd-Sr-Cu-O and the Tl-Pb-Nd-Sr-Cu-O systems. The highest onset temperature is observed at 44 K in the Tl-Pb-Nd-Sr-Cu-O system. The superconductivity of the samples was confirmed by both the resistivity and ac susceptibility measurements. Introduction of PbO into the Tl-Nd-Sr-Cu-O system stabilizes the superconducting phase, as was observed in the Bi-Sr-Ca-Cu-O or the Tl-Sr-Ca-Cu-O system. The superconducting properties in the systems Tl-Pb-L-Sr-Cu-O, with L denoting lanthanide elements other than Nd are also discussed.