Growth, structure and annealing behaviour of epitaxial ZrO2 films on Pt(111)

For future investigations of catalytic reactions on sulfated ZrO2 surfaces by means of scanning tunneling microscopy (STM), ZrO2 films are prepared on Pt(111) and characterized by STM and low-energy electron diffraction (LEED). The films are prepared by vapor deposition of Zr in an O-2 atmosphere followed by annealing (also in an O-2 atmosphere). Conditions are searched where well-ordered, continuous and smooth ZrO2 films are formed. Depositing the films according to literature data at room temperature [Surf. Sci. 237 (1990) 166] yields films with, hillock morphology which decay during annealing and loose continuity. The desired film perfection is attained, however, if the films are deposited at 470 K and postannealed at 950 K. Continuous films are obtained displaying large terraces and a clear p(1 x 1) ZrO2(111) LEED pattern. A splitting of the LEED spots reveals that the films are slightly rotated with respect to Pt(111). However, annealing the films at temperatures >1000 K again yields discontinuous films which indicates the metastable character of the ZrO2 films on Pt(111) substrate. (C) 2003 Elsevier Science B.V. All rights reserved.