Crystal Structure Analysis Using High-Resolution Synchrotron Radiation Powder Diffraction Data.

Abstract

Instrumentation and data analysis techniques for the crystal structure analysis using SR and laboratory X-ray powder diffraction data have been described. The SR powder diffractometer with the MDS has been developed, and it has been used for obtaining high-resolution powder diffraction intensity data at the PF in Tsukuba. The whole-powder-pattern decomposition method, incorporating the sophisticated profile function, has been developed, and integrated intensities of individual reflections could be extracted easily from complex powder patterns. The integrated intensity data sets thus obtained were used for solving crystal structures ab initio by direct methods and/or direct-space methods. At a final stage of crystal structure analysis of crystalline powder, structural parameters are refined by the Rietveld method. Accuracy of the refined structural parameters has been greatly improved by the introduction of the new weight function into the least-squares refinement. Developments of both the instrumentation and the analysis techniques operate complementarily in order to surmount the difficulty intrinsic in the powder diffraction method