Superconductivity in the Tb-Tl-Ba-Cu-O system

Superconductivity with T_c(onset)=100 K, T_c(midpoint)=84 K and T_c(zero)=72 K in the Tb-Tl-Ba-Cu-O system has been observed. X-ray diffraction as well as energy dispersive spectrometric studies were carried out to determine the probable composition and crystal structure of the superconducting phase. The authors propose that Tb-substituted Tl₂Ba₂CuO₆ is responsible for superconductivity at 84 K. Tb⁴⁺ substitution at both Tl³⁺ and Ba²⁺ sites is proposed; these substitutions would effectively reduce the hole concentration, or overdoping, of the parent Tl₂Ba₂CuO₆ compound, leading to enhanced superconducting properties.