Abstract A set of x-ray powder diffraction data of the high-Tc superconductor Bi2Sr2Ca1Cu2Oy (Bi-2212) was simulated based on the experimental single-crystal diffraction data by merging together reflections with diffraction angles (2$\theta$) closer to each other than 0.04 degrees. There are three types of overlapping in the powder diffraction data, i.e. (i) overlapping of main reflections; (ii) overlapping of satellite reflections and (iii) overlapping of main and satellite reflections. The third type of overlapping was first separated into main and satellite components according to the ratio between the average intensity of that of types (i) and (ii). Then the overlapped reflections of main reflections and those of the satellites were uniformly partitioned. Heavy-atom sites in the basic/average structure were found using the uniformly decomposed main reflections by the conventional direct method. Phases of the satellites were derived by the multidimensional direct method. The resultant four-dimensional Fourier maps revealed correctly the essential feature of the modulation. No assumption on either the basic structure or the modulation is needed.
Received: 04 April 2003
Revised: 12 May 2003
Accepted manuscript online:
Fund: Project supported by the National Natural Science Foundation of China, (Grant No 19974068) and the Ministry of Science and Technology of China, (Grant No NKBRSF G1999064603).
Cite this article:
Chen Jian-Rong (陈建荣), Gu Yuan-Xin (古元新), Zheng Chao-De (郑朝德), Fan Hai-Fu (范海福) Ab-initio determination of the incommensurate modulated structure of Bi-2212 from x-ray powder diffraction data －a simulation 2003 Chinese Physics 12 1261
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