Processes for making Tl-Ca-Ba-Cu-O, Tl-Sr-Ba-Cu-O and Tl-Sr-Cu-O superconductors by solid state synthesis

A new high temperature superconducting system with transition temperature above 120 K is disclosed. One superconductor in that system in a preferred embodiment comprises TlRBaCuO wherein R is chosen from Group 2A elements excluding Ba. In a preferred embodiment, the superconductor is TlCaBaCuO. In another preferred embodiment, the superconductor comprises TlSrCuO. Processes for making high temperature superconducting systems are also disclosed