Synthesis and superconductivity of anew 1222-type Tl-based layered cuprate (Tl, Nb) Sr 2(Nd, Ce)2Cu2Oz

Synthesis and superconductivity of a new 1222-type layered cuprate (Tl 1−x Nb x )Sr 2 (Nd 1−y Ce y ) 2 Cu 2 O z have been studied. The structure of this cuprate is directly related to that of Nb-1222 NbSr 2 (Nd, Ce) 2 Cu 2 O z with tetragonal body-center lattice. Partial substitution of Tl for Nb in Nb-1222 phase improves its superconductivity. (Tl 1−x Nb x )Sr 2 (Nd 0.75 Ce 0.25 ) 2 Cu 2 O z samples prepared by the typical procedure exhibit superconductivity with T c of 30-40 K. Effects of Tl and Nb on superconductivity of this cuprate are briefly discussed