High temperature superconductor system comprising Tl2 Ba2 CuO6 + delta

A high temperature superconducting system has the general composition Tl-R-X-Y, wherein: R is a Group 2A element; X is a Group 1B element; and Y is a Group 6A element. Preferably, the composition has the following formula Tl-Ba-Cu-O. The high temperature superconductor of the present invention has a transition temperature of about 90 K with the probability of one phase superconducting at a temperature perhaps as high as 270 K. Processes for making the high temperature superconductor are also provided