Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 26: Particles and clusters I
O 26.1: Talk
Tuesday, March 28, 2006, 15:45–16:00, WIL A317
Growth and in-situ oxidation of Rhodium nanoparticles on α−Al2O3(0001) — •Philipp Nolte, A. Stierle, N. Kasper, C. Ellinger, N.Y. Jin-Philipp, G. Richter, and H. Dosch — Max-Planck-Institute for Metals Research, Heisenbergstraße 3, 70569 Stuttgart
To understand the catalytic activity of 4d transition metal nanoparticles, it is important to study their oxidation behaviour. In general, due to their reduced dimensions and their interaction with the support, the oxidation will differ from the corresponding single crystal surfaces, for example in the ability to form surface oxide layers. We studied the growth and oxidation of Rh particles on the α−Al2O3(0001) surface.
Rh-nanoparticles on α−Al2O3(0001) can be grown by electron beam evaporation in UHV. As we deduce from x-ray diffraction, the particles grow (111)-oriented and epitaxially. The surface lattice can nearly be described by a R(√3× √3)30∘-orientation on the substrate, but with a lattice mismatch of 2%. For an effective material deposition of 2 nm, the formation of flat particles with the shape of truncated hexagonal pyramids could be observed by transmission electron microscopy.
In an in-situ x-ray diffraction experiment at the MPI-MF beamline at ANKA, we studied changes of Crystal Truncation Rods of the Sapphire surface after evaporation of Rh to obtain information about the metal-support interface. The formation of Rh2O3 could be observed in an atmosphere of molecular oxygen with p=3·10−2 mbar and a substrate Temperature TS=400∘ C.