Beeke Gerken; Christoph Mahr;  Jakob Stahl; Tim Grieb; Marco Schowalte; Florian F. Krause; Thorsten Mehrtens; Lutz Mädler and Andreas Rosenauer

Particle and Particle Systems Characterization 40 (2023)

doi: https://doi.org/10.1002/ppsc.202300048

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.

© 2023 The Authors. Particle & Particle Systems Characterization published by Wiley-VCH GmbH.