A transmission electron microscope and group theoretical study of the new Bi-based high-Tc superconductors and some closely related Aurivillius phases
The Bi-based superconductors of approximate compositions Bi2Sr2CuO6 and Bi2Sr2CaCu2O8, and the closely related Aurivillius phases, Bi2BaNb2O9 and Bi4Ti3O12, are discussed from a group theoretical point of view. The structural complexities associated with these phases are treated in terms of successive modulation of an appropriately chosen parent structure. The space-group symmetries of the two Aur