Crystal structures of silica clathrate compounds and absorption mechanism of guest molecules

（1）在400K下，用带CCD探测器的单晶衍射仪测量了黑金云母的X射线强度，分析了客体分子与硅骨架相互作用的动力学性质。建议CCD探测器足够精确，但需要更高角度的数据来分析相互作用。（2）使用安装有大规模存储器的计算机进行的分子动力学模拟未能成功地详细再现X射线结构、结构变化和变形。（3）水热合成了含CH_4、CO_2、N_2、NO、H_2O分子的SiO_2笼形物。成功地合成了黑金云母单晶，并确定了合成的具体步骤。（4）计划使用高压金刚石对顶砧室进行实验研究，例如X射线衍射，以研究客体分子与二氧化硅框架之间的相互作用，以避免在环境条件下实验遇到的困难，其中转化 关于我们 双晶化是不可避免的。这项工作正在进行中。（5）分子动力学模拟其他二氧化硅如石英通常是成功的。我们考虑了为什么这种低密度二氧化硅结构的计算失败。总之，我们得出了一个结论，无论是从实验还是理论的角度来看，对原子无序的详细研究都是必要的。鳞石英是一种具有开放结构的二氧化硅，迄今为止已经积累了大量研究的结构细节，预计这种类型的研究将更容易进行。然后，我们进行了X射线分析，用CCD检测器和拉曼研究测量强度。并发现原子无序运动与声子模之间存在很强的相关性。到目前为止，还没有基于这种类型的耦合的概念被提出用于这些二氧化硅结构。(6)To若进一步利用电脑模拟技术，我们可能需要更精密的势能模型，才能比较原子无序的细节。少

(1)X-ray intensities of melanophlogite were measured at 400K on a single crystal diffractometer with CCD detector to analyze dynamic nature of interactions betweenguest molecules and silica frameworks. It is suggested that CCD detector is accurate enough, but higher angle data are necessary for analyzing the interactions.(2)Molecular dynamics simulation, performed with a computer installed with large scale memories, did not succeed to reproduce the X-ray structures, structural changes and deformations in details.(3)Hydrothermal syntheses of silica clathrates containing CH4,CO2,N2,NO,H2O molecules were attempted. Melanophlogite single crystals were successfully synthesized and the details of syntheses were established.(4)Experimental studies such as X-ray diffractions to investigate interactions between guest molecules and silica frameworks were planned for the use of high pressure diamond anvil cell to avoid difficulties encountered in experiments at ambient conditions, where transform … More ation twinning is inevitable. This is under progress.(5)Molecular dynamics simulations for other silicas like quartz are usually successful. We considered why the calculations failed for such low-density silica-structures. After all we arrived at a conclusion that detailed studies about atomic disorder are essentially necessary for either experimental or theoretical point of view. This type of study is expected to be done more easily for tridymite, a silica with an open structure, on which structural details based on a large numbers of studies have been accumulated so far. We then performed X-ray analyses with intensities measured with a CCD detector and Raman studies. and found strong correlations between atom disordering motions and phonon modes. No concept based on this type of coupling has been proposed for these silica structures so far.(6)To go further with the computer simulation technique, we may need more sophisticated potential energy models to compare with the details involving atom disorder. Less