Atomic resolution analysis of porous solids: A detailed study of silver ion-exchanged zeolite A

Abstract

Currently, aberration corrected scanning transmission electron microscopy is a powerful technique to observe with the maximum resolution of all kinds of materials. Unfortunately, this advanced technique has failed in its application to porous solids such as zeolites, which are extremely beam sensitive inorganic solids. By controlling the beam current we have successfully managed to image the most beam sensitive zeolite, zeolite A (LTA type, Si/Al = 1) and observe the distribution of silver within the cages, observing for the first time silver octahedra composed of six atoms. These results open up the possibility of applying this technique to any zeolitic framework with the potential capability of even observing the oxygen distribution. Some preliminary results using an annular bright field (ABF) in combination with the HAADF detectors on ZSM-5 (MFI type) zeolite are also presented in this manuscript demonstrating the possibility of obtaining real atomic resolution images of the zeolitic framework.