[Zurück]

H. Li, Ch. Rameshan, C Weilach, G. Rupprechter:
"Using synchrotron based XPS to charactreize ZrO2 ultrathin film grown on Pt3Zr";
Poster: Research at European Neutron and Synchrotron Facilities by Austrian Scientists, Wien; 11.11.2013 - 12.11.2013; in: "Research at European Neutron and Synchrotron Facilities by Austrian Scientists", TU Wien, (2013), S. 65.

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.
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) based on synchrotron radiation. The structure of the film is characterized by
Scanning Tunneling Microscopy (STM).
Besides a signal for metallic zirconium from the substrate (Zr-substrate ), XPS showed two distinctive
oxidic species (Zrist and Zr20 ct) upon oxidation at 673 K and post-annealing at 1023 K. With increasing
photon energy, the ratio between Zr2nd and Zr181 increased, indicating that Zr2nd are located in a deeper
layer than Zr1st· After post-annealing of the 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 Zr2nct shown by XPS. Therefore, Zrist and Zr2nct could be assigned to Zr
oxide species within the trilayer thin film and Zr oxide specie in the clusters, respectively.

ZrO2, Thin film, Synchrotron