[Zurück]

H. Li, C Weilach, J. Choi, M. Schmid, G. Rupprechter:
"Preparation and characterization of Zr02 thin films grown on Pt3Zr";
Poster: COST Action CM1104 "Reducible oxide chemistry, structure and functions" Working Groups Meeting, Vienna, Austria; 18.04.2013 - 19.04.2013.

Introduction
Zr02 is widely used in the field of heterogeneous catalysis, and is known as an excellent
support and catalysts material itself [ 1]. However, microscopic mechanisms of the functions
of Zr02 and of the oxide-metal interactions need to be better understood. In order to conduct
fundamental studies on Zr02 via a surface science approach, thin film model catalysts have
been prepared and characterized.
Experimental
In this study, a previously described route was followed to obtain well-ordered and ultra-thin
zirconia film [2]: A cleaned Pt3Zr (0001) alloy substrate was oxidized at 673 K, followed by
post-annealing at 1023 K. The chemical composition of the film is investigated by high
resolution X-ray Photoelectron Spectroscopy (XPS). The structure ofthe film is characterized
by Scanning Tunneling Microscopy (STM).
Results
Besides a signal for metallic zirconium from the substrate (Zrrn,s), XPS showed two
distinctive oxidic species (Zr1,0 and Zr2,0 ) upon oxidation at 673 K and post-annealing at 1023
K. With increasing photon energy, the ratio between Zr2,o and Zri ,o increased, indicating that
Zr2,oare located in a deeper layer than Zr1,0 . After post-annealing ofthe oxide at 923 K, STM
detected many small clusters with a height of about lnm, in addition to the film terraces.
Increasing the annealing temperature to 1023 K led to the disappearance of a considerable
amount of the small clusters, accompanied by the significant decrease of the intensities of
Zr2,0 shown by XPS. Therefore, Zr1,0 and Zr2,0 could be assigned to Zr oxide species within the
trilayer thin film and Zr oxide specie in the clusters, respectively.

ZrO2, Thin film