Abstract:
The TlCa1-xLxSr2Cu2Oy (L=Y or a rare earth element) series of cuprates possessing a (1:1:2:2)-type layered structure exhibit superconductivity in the 60–90-K region. The TlCa1-xLxSr2Cu2Oy (x=1) series of cuprates also possess the (1:1:2:2)-type structure, but are not superconducting. A change in the conduction mechanism seems to occur in the TlCa1-xLxSr2Cu2Oy system with a change in x. Partial substitution of Tl by Pb does not favor superconductivity in this series of cuprates.
