High Resolution Electron Microscopy of Intergrowth and Modulated Structure in 110 K High-Tc Superconductor Bi2(Sr, Ca)4Cu3Oy

Abstract
The high-T c superconductor Bi2(Sr, Ca)4Cu3O y with T c=110 K is examined by high resolution electron microscopy. Most of the perovskite-related layers are composed of three CuO2 and four (Sr, Ca)O layers, separating two Bi2O2 layers by 1.8 nm. Intergrowths of perovskite-related layers containing two, four and five CuO2 layers are observed, where the Bi2O2 layers are separated by 1.5, 2.1 and 2.4 nm, respectively. The structural modulation, similar to that reported in the 80 K low-T c superconductor Bi2(Sr, Ca)3Cu2O y (Y. Matsui et al.: Jpn. J. Appl. Phys. 27 (1988) L372), is also observed.