Incommensurate structure in the Bi-Sr-Ca-Cu-O 80-K superconductor

We report on the structure and characterization of the major phase in the Bi-Sr-Ca-Cu-O system that becomes superconducting below 80 K. A superlattice modulation in the structure that is incommensurate with a tetragonal perovskite-based subcell is observed using electron diffraction. High-resolution imaging indicates that the modulation occurs primarily in bismuth-rich layers in the structure. © 1988 The American Physical Society.