Direct imaging of local atomic structures in zeolite using novel low-dose scanning transmission electron microscopy

TL;DR

This study demonstrates a new low-dose STEM imaging technique that enables direct visualization of atomic structures in sensitive zeolites, revealing detailed local atomic arrangements and twin boundaries.

Contribution

The paper introduces and applies a novel low-electron-dose imaging method, OBF STEM, for atomic-resolution observation of zeolites, overcoming previous limitations due to electron sensitivity.

Findings

Successfully visualized all atomic sites in zeolite framework

Directly characterized twin boundary atomic structures

Enhanced imaging efficiency by two orders of magnitude

Abstract

Zeolites have been used in industrial applications such as catalysts, ion exchangers, and molecular sieves because of their unique porous atomic structures. However, the direct observation of zeolitic local atomic structures via electron microscopy is difficult owing to their low resistance to electron irradiation. Subsequently, the fundamental relationships between these structures and their properties remain unclear. A novel low-electron-dose imaging technique, optimum bright-field scanning transmission electron microscopy (OBF STEM) has recently been developed. It reconstructs images with a high signal-to-noise ratio and a dose efficiency approximately two orders of magnitude higher than that of conventional methods. Herein, we performed low-dose atomic-resolution OBF STEM observations of an FAU-type zeolite, effectively visualizing all the atomic sites in its framework. Additionally, the complex local atomic structure of the twin boundaries in the zeolite was directly characterized. The results of this study facilitate the characterization of the local atomic structures in many electron-beam-sensitive materials.