Influence of lead(II) sulphide on the formation and superconductivity of (Tl1-Pb )Sr2CaCu2O7 (x = 0.1 – 0.8)

Abstract

The influence of lead(II) sulphide (PbS) on the formation and superconducting behaviour of (Tl1-xPbx)Sr2CaCu2O7 (Tl-1212) phase for x = 0.1, 0.3, 0.4. 0.5, 0.7 and 0.8 was investigated. The samples were prepared using the solid-state reaction method. Lead(II) sulphide was used as the source for Pb. The XRD patterns showed majority Tl-1212 phase along with other impurity phases including PbSO3. The highest onset transition temperature, Tc-onset = 104 K was observed in the x = 0.8 sample. This is higher than (Tl0.4Pb0.6)Sr2CaCu2O7 prepared using PbO where Tc-onset = 97 K. The average nanoscale crystalline grain size calculated based on the Scherrer-Warren equation was in the range of 22-101 nm. AC susceptibility measurements showed that the transition temperature, Tc' increased as PbS content was increased. This works showed that diamagnetic PbS enhanced the electrical properties of individual superconducting grains for Tl-1212 phase. The effectiveness of PbS versus PbO on the Tl-1212 superconductor is also discussed in this paper.