An electron diffraction and group theoretical study of the new Bi-based high-temperature superconductor

Abstract

An electron microscopy study of the new Bi-based high-temperature superconductor reveals an incommensurately modulated, pseudo-tetragonal, layered structure strongly reminiscent of the so-called Aurivillius phases. The systematic extinction conditions associated with the matrix and satellite reflections allow two possible space group symmetries for the average structure and two possible superspace group symmetries for the modulated structure. A structural model consistent with the above symmetry constraints is presented.