Material Discrimination in Nanoparticle Hetero-Aggregates by Analysis of Scanning Transmission Electron Microscopy Images |
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Authors: | Beeke Gerken Christoph Mahr Jakob Stahl Tim Grieb Marco Schowalter Florian F. Krause Thorsten Mehrtens Lutz Mädler Andreas Rosenauer |
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Affiliation: | 1. Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany;2. Leibniz Institute for Materials Engineering – IWT, Badgasteiner Str. 3, 28359 Bremen, Germany |
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Abstract: | Hetero-contacts are interfaces between different materials at the nanoscale leading to novel functional properties. In hetero-aggregates, primary particles of at least two different materials are mixed at primary particle or cluster level. Double flame spray pyrolysis (DFSP) is a versatile technique for the controlled synthesis of such materials. Characterization of hetero-aggregates by scanning transmission electron microscopy (STEM) requires acquisition and evaluation of many aggregate images in order to derive statistically significant results. Usually, STEM energy dispersive X-ray spectroscopy (EDXS) is used to acquire elemental maps providing the material distribution of the primary particles within hetero-aggregates. However, the acquisition of a single EDXS map takes up to several minutes. For this reason, determination of material types of primary particles from the intensity in high-angle annular dark field STEM images alone is desirable. These images can be acquired within a couple of seconds. In the present work, a method is suggested which allows for achieving this objective. It can be applied to distinguish materials with a significant difference in their atomic number and hence sufficient material contrast in the STEM images. |
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Keywords: | double flame spray pyrolysis energy-dispersive X-ray spectroscopy hetero-aggregates hetero-contact nanoparticle mixing scanning transmission electron microscopy |
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