Superconducting Phases with Single Tl-O Layer Structure Preparation: (Tl, Pb)Ca_n-1Ba₂Cu_nO_2n+3 (n=2, 3, 4, 5, 6)

Abstract

Single Tl-O layer structures with two to six Cu-O layers, (Tl, Pb)Ca n -1 Ba 2 Cu n O 2 n +3 ( n =2, 3, 4, 5, 6), are prepared, and the superconducting properties of their phases are investigated. The c -lattice constants of the observed phases obey the c -axis rule of c =6.38+3.19 n for single Tl-O layer structures. With an increase in Cu-O layers, the superconducting transition temperature, determined from electrical resistivity-temperature dependency and DC susceptibility, rises, reaching a maximum value of 121 K at n =4, and then falls with a further increase of the number of Cu-O layers from four to six.