Atomic-resolution analysis of the structure and dopants of beam sensitive ordered porous materials

Abstract

With the modern transmission electron microscopes (TEM) sub‐angstrom resolution has become readily achievable overcoming the lateral resolution problem. However, there are many cases where its fully potential cannot be totally exploited due the strong interaction between the high energetic electron beam and the material. Zeolites, zeotypes and metal organic framework (MOFs) suffer from this interaction resulting in an irreversible framework disruption through a radiolytic mechanism[1].

Since the pioneers electron microscopy observations of zeolites in the 70's, its application and image resolution has been always been limited by this high sensitivity making impossible to fully exploit the TEM capabilities. However, in recent years with the introduction of the spherical aberration correctors and paying special attention to the electron dose, images with unprecedented resolution has been able to be obtained, making feasible the truly identification of the atoms conforming the structure.

In here, it will be presented atomic‐column resolution images which will provide new information on guest species[2] within the zeolite cavities, as well as the observation of structural defects[3] providing new information about the ion exchange properties of these solids. Figure 1 displays the data obtained after introducing rare earth metals into ETS‐10.

Furthermore, it will be shown how aberration corrected STEM provide unique information dealing with the analysis of new complex materials[4]; making able the observations of pores linked by single four‐rings, double four‐rings or oxygen linkers.