THE COMPARISON OF STRUCTURAL CHARACTERISTICS BETWEEN 2212 AND 2201 PHASES IN THE BI-SR-CA-CU-O SYSTEM

The Laue and Bragg diffraction patterns of a Bi-based 2212-phase (Bi2Sr2CaCu2Oy) single crystal have been investigated by Laue photography using continuous radiation and monochromatic radiation, and compared with those of a Bi-based 2201-phase (Bi2Sr2CuOz) single crystal. It is found that there are a two-dimensional lattice and a three-dimensional lattice in the Bi-based 2212-phase crystal, which are structurally independent of each other. However, there is only a three-dimensional superlattice in the Bi-based 2201-phase crystal. Combining these results with the reported results of high-resolution electron microscope research, it is suggested that ''Bi-concentrated'' bands of the Bi-based 2201 phase have entirely entered into the lattice of the parent structure formed by CaCuO2 [1], but not of the Bi-based 2212 phase, i n which the ''Bi-concentrated'' band formed a lattice itself.