Self-organization mechanisms in a Fe-Au film: from isolated core-shell to multicore nanoparticles
CEMES, CNRS UPR 8011 and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse, France
2 Centre de MicroCaractérisation Raimond Castaing, Université de Toulouse, 3 rue Caroline Aigle, F-31400 Toulouse, France
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Received in final form: 18 March 2022
Accepted: 28 March 2022
Published online: 1 June 2022
Many nanotechnological applications necessitate a high density of nanoparticles (NPs), making NP morphology control highly challenging. In this work, the morphology of bimetallic NPs formed by magnetron sputtering deposition of a Fe(3 nm)-Au(2 nm) bilayer film on an amorphous silica substrate is analyzed using high-angle dark-field scanning transmission electron microscopy (HAADF-STEM). While all the NPs adopt a Fe-Au core-shell chemical order, they can be sorted into three different types. Isolated NPs, displaying either a highly symmetric centered core geometry (CC-type) or an asymmetrical off-centered core geometry (OC-type), are observed despite the rather large metallic volume. The majority of the NPs however displays a multicore geometry, with Fe cores in the 10-12 nm range, larger than the NPs observed in a pure Fe (3nm) film grown under identical conditions. The driving forces leading to the different morphologies are discussed together with the role played by the environnement.
© S. Combettes et al., Published by EDP Sciences, 2022
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