Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 2: Topical Session TEM I

MM 2.5: Vortrag

Montag, 14. März 2011, 12:30–12:45, IFW A

Electron beam induced surface diffusion on metallic nanoparticles — •Alexander Surrey¹, Darius Pohl¹, Ulrich Wiesenhütter², Ludwig Schultz¹, and Bernd Rellinghaus¹ — ¹IFW Dresden, Helmholtzstr. 20, D-01156 Dresden, Germany — ²FZ Dresden, Postfach 510119, D-01314 Dresden, Germany.

The predominant mass transport mechanism during the coalescence of adjacent metallic nanoparticles is assumed to be surface diffusion. Upon exposure to an electron beam in a transmission electron microscope (TEM) the diffusion of surface atoms towards the sintering neck is stimulated thereby reducing the particles's surface free energy. This electron beam induced inter-particle coalescence is investigated in FePt and Au nanoparticles with icosahedral or truncated octahedral structure by means of aberration-corrected TEM. The particles are prepared by inert gas condensation which provides for free and uncovered surfaces. Aberration-corrected TEM is employed to monitor and analyze quantitatively temporal changes of the surface atom configurations on particle facets oriented parallel to the electron beam. It is observed that the path of the surface atoms towards the sintering neck is chosen to always optimize the local coordination. The influence of the electron energy (which can be chosen by adjusting the acceleration voltage) on the beam-induced surface diffusion is discussed.