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MM: Fachverband Metall- und Materialphysik
MM 52: Topical Session: In Situ and Multimodal Microscopy in Materials Physics II
MM 52.7: Talk
Thursday, March 21, 2024, 12:30–12:45, C 130
Reducing electron beam-induced defect formation by using in situ TEM gas cell — •Carina B Maliakkal1, Paolo Dolcet2, Lukas Braun2, Maria Casapu2, Di Wang1, and Christian Kübel1 — 1Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMFi), Campus North, Karlsruhe Institute of Technology (KIT), Germany. — 2Institute of Technical and Polymer Chemistry, KIT
Ceria -- a very common oxide support used in exhaust gas catalysis -- was initially investigated to obtain spatially resolved quantitative information about the surface speciation. Electron energy loss spectroscopy (EELS) mapping in a Scanning Transmission Electron Microscope (STEM) was used for this purpose. We did not observe any noticeable change in the crystal structure or surface structure via simple STEM imaging. However, during our investigation to check the Ce oxidation state via EELS, we found that the extent of oxygen vacancies near the ceria surface is strongly affected by the electron beam under the TEM vacuum conditions. This is not surprising, as it is known that the electron beam can significantly alter some materials.[1] Traditional approaches to reduce electron-beam induced damage includes adjusting the high tension, electron dose and dose rate. However, since here the major damage/alteration to the ceria seems to be the induced creation of oxygen vacancies, we demonstrate that by working in oxygen atmosphere, the damage can be successfully compensated for.
Reference [1] Neelisetty et al. Microscopy and Microanalysis 2019 (25) 592.
Keywords: Transmission electron microscopy; Surface reduction; vacancy generation; Electron energy loss spectroscopy; TEM