Copper oxycarbonates with a layered structure, new promising high Tc superconductors

Abstract

The ability of CO 3 groups to accomodate the perovskite framework opens the route to the possible synthesis of new copper oxycarbonates with a layered structure, which must be considered as promising high Tc superconductors. A review of the crystal chemistry of these recently synthesized new materials is given here. The best performance has been reached for the oxycarbonate Tl 0.5Pb 0.5Sr 4Cu 2CO 3O 7 which exhibits a Tc up to 70 K and a Meissner volume fraction of 70% at 4.2 K.