The effect of heat treatment on the morphology and mobility of Au nanoparticles

Sven Oras; Sergei Vlassov; Simon Vigonski; Boris Polyakov; Mikk Antsov; Vahur Zadin; Rünno Lõhmus; Karine Mougin

doi:10.3762/bjnano.11.6

The effect of heat treatment on the morphology and mobility of Au nanoparticles

Beilstein J Nanotechnol. 2020 Jan 6:11:61-67. doi: 10.3762/bjnano.11.6. eCollection 2020.

Authors

Sven Oras^{1

2

3}, Sergei Vlassov¹, Simon Vigonski⁴, Boris Polyakov⁵, Mikk Antsov¹, Vahur Zadin⁴, Rünno Lõhmus¹, Karine Mougin²

Affiliations

¹ Institute of Physics, University of Tartu, W. Ostwaldi tn 1, 50412, Tartu, Estonia.
² Université de Strasbourg, Université de Haute Alsace, Institut de Science des Matériaux, IS2M-CNRS-UMR 7361, 15 Rue Jean Starcky, 68057 Mulhouse, France.
³ Tallinn University of Technology, Tartu College, Puiestee 78, Tartu, 51008, Estonia.
⁴ Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia.
⁵ Institute of Solid State Physics, University of Latvia, Kengaraga street 8, LV-1063 Riga, Latvia.

Abstract

In the present paper, we investigate the effect of heat treatment on the geometry and mobility of Au nanoparticles (NPs) on a Si substrate. Chemically synthesized Au NPs of diameter ranging from 5 to 27 nm were annealed at 200, 400, 600 and 800 °C for 1 h. A change in the geometry from faceted to more rounded shapes were observed with increasing annealing temperature. Kinetic Monte Carlo simulations indicate that the NPs become rounded due to the minimization of the surface area and the transition to lower energy surface types {111} and {100}. The NPs were manipulated on a silica substrate with an atomic force microscope (AFM) in tapping mode. Initially, the NPs were immovable by AFM energy dissipation. However, annealed NPs became movable, and less energy was required to displace the NPs annealed at higher temperature. However, after annealing at 800 °C, the particles became immovable again. This effect was attributed to the diffusion of Au into the Si substrate and to the growth of the SiO₂ layer.

Keywords: Au nanoparticles; annealing; atomic force microscopy (AFM); manipulation; melting; nanotribology.

Grants and funding

This work was supported by The Centre National de la Recherche Scientifique (CNRS) of France and the French Embassy Program. The authors are also grateful for partial support by COST Action CA15216, the Estonian Science Foundation (grants PUT1689 and PUT1372), the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts, ZEBE, grant 2014-2020.4.01.15.0016 and Latvian Science Council grant lzp- 2018/2-0083.