Zhang Yaping, Smith Daniel, Readman Jennifer E, Mayoral Alvaro
Center for High-Resolution Electron Microscopy (CℏEM), School of Physical Science and Technology (SPST), ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, China.
School of Physical Sciences and Computing, University of Central Lancashire, Preston PR1 2HE, United Kingdom.
J Phys Chem C Nanomater Interfaces. 2021 Mar 25;125(11):6461-6470. doi: 10.1021/acs.jpcc.1c00550. Epub 2021 Mar 15.
The understanding of the structural framework and metal locations within zeolites are two critical aspects to tune and further exploit their properties as heterogeneous catalysts, advanced optical devices, or as water remediation materials. The development of electron microscopy has made it possible to observe directly the zeolitic framework and the distribution of extra framework cations within the pores at the atomic level. Here, we have studied the framework providing data with an unprecedented spatial resolution, which have allowed the analysis of the domains present in the framework. Additionally, potassium and lead (introduced by aqueous ion exchange), which were nonperiodically distributed in the pores have been located. An alternative image mode, annular bright field, has been used, proving its usefulness to extend the spatial resolution and increase the sensitivity toward light elements such as bridging oxygen. Finally, the combination of atomic imaging (local information) with the three-dimensional electron diffraction tomography analysis (averaged information) determined the lead- crystal symmetry to be 6 .
了解沸石内部的结构框架和金属位置是调整并进一步开发其作为多相催化剂、先进光学器件或水修复材料的性能的两个关键方面。电子显微镜的发展使得直接在原子水平上观察沸石骨架和孔内骨架外阳离子的分布成为可能。在这里，我们研究了该框架，以前所未有的空间分辨率提供数据，这使得对框架中存在的畴进行分析成为可能。此外，通过水离子交换引入的钾和铅在孔中呈非周期性分布，它们的位置已被确定。一种替代的成像模式，环形明场，已被使用，证明了它在扩展空间分辨率和提高对诸如桥连氧等轻元素的灵敏度方面的有用性。最后，原子成像（局部信息）与三维电子衍射断层分析（平均信息）的结合确定了铅晶体的对称性为6 。
