Gerken, Beeke
[Author];
Mahr, Christoph
[Author];
Stahl, Jakob
[Author];
Griebel, Tim
[Author];
Schowalter, Marco
[Author];
Krause, Florian Fritz
[Author];
Mahrtens, Thorsten
[Author];
Mädler, Lutz
[Author];
Rosenauer, Andreas
[Author]
Material discrimination in nanoparticle hetero-aggregates by analysis of scanning transmission electron microscopy images
Description:
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.