Electrical Conductivity, Magnetic Susceptibility, and Infrared Spectra in the Superconducting Systems Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O

Since the properties of the high temperature superconducting systems Tl-Ba-Ca-Cu-O and Bi-Sr-Ca-Cu-O depend very sensitively on composition and structures various preparation methods are applied and the products are tested by measuring the transport and magnetic susceptibility properties together with their IR‐spectra. Most samples show multiphase structure. The highest transition temperature with zero resistance Tco ≈ 125 K, is found in the system Tl-Ba-Ca-Cu-O, which is lowered to Tco ≈ 102 K in the case of doping with Ag.