Electron crystallography of zeolites: structure information from HREM images and electron diffraction patterns

摘要

High resolution electron microscope (HREM) images of zeolites have typically been used for crystal structure interpretation of frameworks. Only under strict conditions (weak phase object approximation), do HREM images represent directly the projected framework potential, otherwise the images are distorted. A large part of those distortions can be determined and compensated for by crystallographic image processing (CIP). This technique has been used to show that new zeolites SSZ-25 and porosil ITQ-1 are isomorphous to the MCM-22 zeolite. CIP and filtering can also be useful in HREM images of zeolite crystals doped with small particles, revealing directly the size and distribution of particles lying on the surface of zeolite matrix.