Abstract:
The structure of Tl0.5Pb0.5CaSr2Cu2Oy (Tc = 90K) has been investigated by neutron diffraction profile analysis and the results discussed in the light of the structures of TlCaBa2CuP2Cy and TlCa0.5Y0.5Ba2Cu2Oy. We find no evidence for disorder in the Tl/Pb sites, but there is some interchange between Ca and Sr sites. The Cu---O bond distances in these cuprates seem to parallel the variation of the superconducting transition temperature in these cuprates.