DIFFUSE SCATTERING STUDY OF Bi₂Sr₂CaCu₂O_d CRYSTALS. Lei Shi^1,2, Takuya Ohba¹, Toru Hara¹, Masahiko Tanaka³, Yuheng Zhang², ¹Departmernt of Materials Science and Engineering, Teikyo University, Utsunomiya 320, Japan, ²Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China, ³Photo Factory, KEK, Tsukuba 305, Japan

Although the crystal structures of Bi-based high-Tc super-conductor, which is distinguished by incommensurate modulations, have been solved for several years, their implications for superconductivity are as yet uncertain. This indicates that the deviation from the average structure also should be considered, which may play an important role for the superconductivity. For this purpose the contour maps of the scattering intensity on b*-c* plane for Bi₂Sr₂CaCu₂O_d single crystals have been observed by both ordinary x-ray and synchrotron radiation. The characteristic feature were obtained in this experiments; that is, the intensity distribution around both the Bragg reflection and its satellites show a strong asymmetry. Both of them are elongated along the c axis, especially for the satellites which connect each other and almost form a rod shape. This reveals that the structure has a strong two-dimensionsl feature, which is coincide with the two-dimensional characteristics of physical transportation. Our observation also confirms the previous results that the modulated wavevector q=q2b*+c* (q2=2.0 - 2.1).

*This work was carried out as part of Teikyo University USTC (University of Science and Technology of China) Coorperative Program.