Effect of Ce substitution on the properties of Tl-based superconductors

Samples with nominal composition (Tl0.5Pb0.5)Sr2-xCexCa2Cu3Oy were pre pare d with x in the range 0 to 0.5, to investigate the role of charge carrier c oncentration on the superconducting properties of TI-based materials. The b ehavior of the normal state resistivity with temperature showed that as x c hanges from 0 to 0.2, the material moves towards optimally doped state. For higher Ce content the normal state resistivity versus temperature, started deviating from linearity. The onset transition temperature increased gradu ally by about 6 K as x was increased from 0 to 0.2. The zero resistance tra nsition temperature rapidly decreased for samples with x > 0.2. Furthermore , XRD analysis revealed that x enters the structure of both Tl-1223 and Tl1 212. These results are discussed in terms of controlling the hole concentra tion in the CuO2 planes through Ce4+ replacement of Sr2+. PACS numbers: 74. 62.Dh, 74.72.Fq.