Abstract
Some recent developments in the application of X-ray and neutron diffraction techniques to zeolite structural problems are summarized. Powder neutron diffraction (PND) has been applied further to studying hydrated materials, hydroxylic proton environments and zeolite-hydrocarbon complexes, as well as to refinements of the framework structures of a range of zeolite and aluminophosphate compositions. High resolution powder diffraction data collected using synchrotron X-radiation has been used for structure solutions and refinements, detection of subtle orderings or symmetry distortions, and quantitative studies of peak broadening phenomena, most notably arising from planar faulting. Techniques necessary for performing diffraction measurements on individual microcrystals >~5μm have been improved and the potential for using Laue geometry (with somewhat larger crystals) to accumulate diffraction data in time scales short enough to permit time-resolved structural studies has been demonstrated. In parallel, there have been continuous improvements in data analysis methods, notably in programs for Rietveld analyses of powder diffraction data, and the development of a new approach to framework structure solution using simulated annealing.
Published Version
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