Properties of the new Bi-Sr-Ca-Cu-O superconductors

We have prepared samples of the new Bi-Sr-Ca-Cu oxide superconductors with various cation ratios and measured their transport and magnetic properties. In Bi1Sr1Ca1Cu2O8+δ two superconducting transitions are observed and high-resolution electron microscopy shows the existence of regions with a superstructure modulated along the b-axis which coexist with regions having a perfectly ordered lattice. © 1988 Elsevier Science Publishers B.V.