Abstract
Superconductivity with T sub(c(onset)) = 100 K, T sub(c(midpoint)) = 84 K and T sub(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. We propose that Tb-substituted Tl sub(2)Ba sub(2)CuO sub(6) is responsible for superconductivity at 84 K. Tb super(4+) and Ba super(2+) sites is proposed; these substitutions would effectively reduce the hole concentration, or overdoping, of the parent Tl sub(2)Ba sub(2)CuO sub(6) compound, leading to enhanced superconducting properties.