Structure and superconductivity of the Bi-, Tl- and Hg-cuprates

We present a comparison of the crystal-chemical properties of the Bi-, Tl-, and Hg-based superconducting cuprates, in relation to their physical prope rties. Despite the global similarity of their layered structures, the diffe rent crystal-chemical nature of these three cations leads to quite differen t structural properties for the three series. The present knowledge of the relationships between crystal-chemical and superconducting properties in th ese systems is presented, with emphasis on the different doping mechanisms observed.