X-Ray Diffraction Studies of Quasicrystals and Other Crystalline Materials

w：\awards\awards96\*.doc 小行星9625585 将对Al-Pd-Mn的二十面体相进行各种X射线衍射实验。 由于这种合金可以制成具有高质量晶格结构的准晶，因此动态衍射是可行的。 最基本的问题仍然是，“原子在哪里？准晶体发现12年后 这个问题还没有完全 回答 在普渡大学和同步加速器光源，NSLS和 国际象棋，将包括定量研究的异常传输（博尔曼效应），驻波，并使用循环 极化 X光片 的 基本 问题 的 将检查中心对称性。 将进行一个实验，以确定苯偶酰分子晶体的空间群，可以发现在两个对映体空间群和相关的光学活性与结构。 各种X射线衍射技术，包括国家同步加速器光源和康奈尔高能同步加速器光源的实验，将被用来研究准晶中的原子排列。 这些是新材料，不像大多数其他固体物质那样表现出长程周期性。 其高强度、低密度、低表面摩擦和良好的抗氧化性使其成为表面涂层的理想选择。 法国的一家公司已经建立了一条生产线，在煎锅中使用准晶涂层代替特氟龙。 设想应用于滚珠轴承， 有些准晶体具有特殊的储氢性能。 ***

w:\awards\awards96\*.doc 9625585 Colella Various x-ray diffraction experiments will be carried out on the icosahedral phase of Al-Pd-Mn. Since this alloy can be made into a quasicrystal with a high quality lattice structure, dynamical diffraction is feasible. The basic question still remains, "Where are the atoms?" and twelve years after the discovery of quasicrystals this question has not been fully answered. Experiments at Purdue and at the synchrotron light sources, NSLS and CHESS, will include quantitative studies of anomalous transmission (the Borrman effect), standing waves, and the use of circularly polarized x-rays. The basic issue of the centrosymmetry will be examined. An experiment will be carried out to determine the space group of the benzil molecular crystal that can be found in two enantiomorphic space groups and correlate optical activity with structure. %%% Various x-ray diffraction techniques, including experiments at the National Synchrotron Light Source and the Cornell High Energy Synchrotron Source, will be used to investigate the atomic arrangements in quasicrystals. These are new materials that do not exhibit long range periodicity as do most other solid substances. Their high strength, low density, low surface friction, and good oxidation resistance make them ideal for surface coatings. A company in France has set up a production line for using quasicrystalline coatings in frying pans instead of Teflon. Applications are envisaged for ball bearings, Some quasicrystals have exceptional qualities for hydrogen storage. ***