Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 29: Nanostructures at Surfaces III: Dots, Particles, and Clusters
O 29.8: Vortrag
Dienstag, 2. April 2019, 12:15–12:30, H25
Structure and surface energies of nanoparticles from atomistic simulations — •David Holec1, Franz Fischer2, and Dieter Vollath3 — 1Department of Materials Science, Montanuniversität Leoben, Austria — 2Franz-Josef-Strasse 18 — 3NanoConsulting, Stutensee, Germany
Nanoparticles are fascinating objects not only from the point of view of diversity of their applications but also from the basic research perspective. In this contribution we review our recent activities directed towards revealing structure and surface energy of Au55 nanoparticle. It turns out that an amorphous structure possesses lower energy than a crystalline or well ordered structure. In this context, the two step process to increase the thermal stability should be mentioned. This process is a new, until now, never described phenomenon. Further on, we shown that surface energy changes dramatically as a function of the radius, in particular for a particle with small effective radius such as Au55. This small change of radius is physically corresponding to the presence of an electronic cloud surrounding atomic radii. By calibrating our calculations to bulk fcc Au mass density we propose that the radius should be about increased by 0.13 nm as compared to convex hull of only ionic positions. Eventually, this correction of the surface energy radius makes is possible to put the contradictory trends from theory (surface energy increases with decreasing particle size) and experiment (surface energy decreases with decreasing particle size) onto a common ground, finally yielding only a slight-to-no particle size dependence.