OBF STEM – Direct Imaging Of Local Atomic Structures In Zeolite

Because of their distinctive porous atomic structures, zeolites are utilized in various industrial applications as catalysts, ion exchangers, and molecular sieves. However, because of poor electron irradiation resistance, direct study of zeolitic local atomic structures by electron microscopy is challenging. Their essential structure-property correlations are, therefore, yet uncertain. Optimal bright-field scanning transmission electron microscopy (OBF STEM), a low-electron-dose imaging method, has just been created. Compared to conventional approaches, it reconstructs images with a high signal-to-noise ratio and dosage efficiency around two orders of magnitude greater.

Here, scientists used low-dose atomic-resolution OBF STEM observations to see every atomic site in the frameworks of two different kinds of zeolites. Additionally, they were able to see the intricate local atomic structure of the twin borders in a zeolite of the faujasite (FAU) type and the low occupancy Na+ ions in eight-membered rings in a zeolite of the Na-Linde Type A (LTA). The findings of this work make it easier to characterize local atomic structures in various materials susceptible to electron beams.

Conventional STEM employs a single annular detector to detect transmitted/scattered electrons to form images. The samples’ electromagnetic fields and phase information may be learned by analyzing these many STEM photos. Theoretically, scientists have created an optimal bright-field (OBF) STEM approach for low-dose imaging that detects atomic structures with the maximum signal-to-noise ratio (SNR) possible by employing segmented/pixelated detectors.

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