New Techniques Development For CCD Detector X-ray Single Crystal Diffraction And Application In Modulated Structure

An X-ray diffractometer (made in Bruker Co. , Germany) with CCD has been installed in the X-ray diffraction Lab of China University of Geosciences (Beijing) in October 2000. In recent years the many of single crystal samples have been determined by the instrument. The samples include synthesize materials, function materials, organic matters, complexes, metal alloys, drugs, natural minerals, precious stones and so on. The new structure that have been published using the test data by the instrument are about 100. It is an important tool in the normal regulations crystal analytical. The new technique development and application in modulated structure research bases on the instrument, the CCD flat detector play an important part in aperiodic crystal diffraction experiment. The applicable fields of CCD have been further broadened especially in the study of modulated structure. In this work, the new results are obtained in the following aspects: Basing on the principle of CCD Diffractometer, 3D simulated experiment of single crystal x-ray diffraction was developed on computer. The software of simulated experiment can be used as diffraction data analysis, crystal directional analysis and diffraction education. A new method for powder-like diffractograms of small single crystals using a SMART CCD detector is introduced. Repeat rotation method and a support software program is developed. Representative data sets attest to the accuracy, efficiency and sensitivity of the method presented. The application of the method can analyze for the X-ray powder diffraction of rare samples. More than twenty specimens from the metal alloy mineral group were analyzed with this new method and dozens of mineral species were identified. The powder diffraction of incommensurate modulated structure of the ankangite was analyzed by this method too, and was indexed with four dimension superspace. Study of modulated structure by X-ray single crystal diffraction, the new results obtained. Incommensurate modulated structure single crystal diffraction data collection method by SMART CCD was introduced, and the many of single crystal diffraction data were obtained. The methods that modulated vectors measured basing on the single crystal diffraction data and reciprocal space diffraction spots indexed with four reciprocal vectors were introduced, and a program was developed for indexing satellite spots. Many of single crystal diffraction data that include commensurate and incommensurate modulated structure samples were collected, and put forward a classification according to reciprocal spots characteristics. The several of minerals of commensurate and incommensurate modulated structure were determined and refined, and acquired the new understanding to the structure characteristics of these minerals.