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Crystal Structure Analysis of Zeolites by Quantitative HRTEM Study

通过定量 HRTEM 研究分析沸石的晶体结构

基本信息

批准号：
07650776
负责人：
OHNISHI Naoyuki
金额：
$ 1.41万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650776/
关键词：
high-resolution electron microscpy electron diffraction crystal structure analysis zeolite 電子回析

项目摘要

We have applied a quantitative high-resolution transmission electron microscopy (HRTEM) technique to the structure analysis for several kinds of zeolite crystals and incorporated molecules inside micropores. First, we applied a slow-scan CCD camera attached to a 400kV HRTEM for improvement in the experimental resolution of contrast details in the synthetic zeolite structure MFI.The additionally resolved contrast features are shown to be due to the presence of organic TPA+(tetrapropylammonium) ions in the structural cage (Channels) of atomic framework of this material. The improvement in the amount and quality of strucutural detail through the use of the CCD camera is also shown by a comparison of a Fourier synthesis, made by using the observed electron diffraction intensities, with another one calculated by using a structure model based on X-ray measurements. The phases for both Fourier maps were calculated from the X-ray data. A comparison of the two Fourier calculations results in a good agreement, although the calculation of the diffraction intensities are based on the kinematical approximation. Rfactors based on the normalized diffraction intensities have also been employed to evaluate the results of the structure analysis. For more detailed structure analysis, we have evaluated an effect of dinamical scattering of electrons by the calculation using the framework structure of zeolite FAU,which is one of the best popular zeolite structure type having a low atomic packing density. The results of calculations indicated that the kinematical approximation can be applied up to the specimen thickness of about 30 nm, and is useful especially for the structure analysis of incorporated guest materials.

本文应用高分辨透射电子显微镜（HRTEM）技术对几种沸石晶体及微孔中的分子进行了定量结构分析。首先，我们应用一个慢扫描CCD相机连接到一个400千伏高分辨透射电子显微镜的合成沸石结构MFI.The额外解决的对比度的细节的实验分辨率的改善被证明是由于有机TPA+（四丙基铵）离子的存在下，在这种材料的原子框架的结构笼（通道）。通过使用CCD相机的结构细节的量和质量的改善也示出了通过傅立叶合成的比较，通过使用所观察到的电子衍射强度，与另一个计算通过使用基于X射线测量的结构模型。从X射线数据计算两个傅立叶图的相位。虽然衍射强度的计算是基于运动学近似的，但两种傅里叶计算的比较结果吻合得很好。基于归一化衍射强度的R因子也被用来评估结构分析的结果。对于更详细的结构分析，我们已经通过使用沸石FAU的骨架结构的计算评估了电子的动力学散射的效果，所述沸石FAU是具有低原子堆积密度的最流行的沸石结构类型之一。计算结果表明，运动学近似可适用于厚度约为30 nm的样品，特别适用于掺杂客体材料的结构分析。