The growth and structure of titanium oxide films on Pt(111) investigated by LEED, XPS, ISS, and STM
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Titanium oxide films grown on Pt(111) have been investigated using LEED, XPS, ISS, and STM for coverages ranging from 1.0 to 5.0 ML. The oxide overlayers are prepared by vapor phase deposition of titanium metal followed by oxidation in 10-6 Torr O2. Partial dissolution of the overlayer into the Pt substrate occurs upon annealing to temperatures in excess of 500°C. Annealing in 1 × 10-6 Torr O2 at temperatures ranging from 500°C to 700°C leads to a three-fold symmetric structure with a unit cell of 18.2 A ̊ × 18.2 A ̊. This structure is observed at coverages ranging from 1.0 to 5.0 ML. XPS measurements of this phase show the stoichiometry of TiO2. Heating in vacuum at 650°C to 850°C leads to a new structure with a unit cell of 18.2 A ̊ × 13.9 A ̊ which is observed at coverages of 1.0 to 1.5 ML. This oxide overlayer is shown by XPS to have the stoichiometry of Ti4O7. Similarities are observed between the ordered overlayers and reported structures of stoichiometric and reduced rutile TiO2 surfaces. Angle resolved XPS measurements of disordered titanium oxide films, formed by annealing at temperatures below 500°C, indicate that reduced Ti3+ is concentrated at the oxide /Pt(111) interface. © 1995.
author list (cited authors)
Boffa, A. B., Galloway, H. C., Jacobs, P. W., Benítez, J. J., Batteas, J. D., Salmeron, M., Bell, A. T., & Somorjai, G. A.