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.

我们已将定量的高分辨率透射电子显微镜（HRTEM）技术应用于微孔内部几种类型的沸石晶体和掺入分子的结构分析。首先，我们应用了连接到400kV HRTEM的慢速CCD摄像头，以改善合成沸石结构MFI中对比度细节的实验分辨率。其他分析的对比特征则是由于有机TPA+（四丙基氨基铵）的存在所致该材料原子框架的结构笼（通道）中的离子。通过使用观察到的电子衍射强度进行的傅立叶合成，通过使用CCD摄像机的使用，通过使用CCD摄像机来提高了结构性细节的数量和质量。射线测量。两个傅立叶图的相位是根据X射线数据计算得出的。对两个傅立叶计算的比较导致了良好的一致性，尽管衍射强度的计算基于运动学近似。基于归一化衍射强度的RFACTOR也已被用于评估结构分析的结果。对于更详细的结构分析，我们使用沸石FAU的框架结构进行了计算，评估了电子dinamical散射的效果，沸石FAU是具有低原子堆积密度的最佳最受欢迎的沸石结构类型之一。计算结果表明，可以将运动学近似值应用于大约30 nm的样品厚度，并且特别适用于掺入的宾客材料的结构分析。