Discommensuration patterns in the BiSrCaCuO high Tc superconductors

Abstract We present a transmission electron microscopy study of the discommensuration (DC) walls in the superconducting bismuth-cuprates. High resolution evidence for the translation slip across a wall is obtained for the first time in these materials. A consistent relationship is established between the observed characteristics of the walls in several phases of this structural family: number of walls merging at a node, average distance between DCs, and value of the modulation wavenumber. We show that a wide range of ‘latent’ commensurate periods, between 4 b and 9 b , determine the characteristics of the walls.