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Structural and compositional characterization of ultrathin titanium oxide films grown on Pt(3)Ti(111).
MedLine Citation:
PMID:  23288493     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
We have investigated the growth of ultrathin titanium oxide (TiO(x)) films on a Pt(3)Ti(111) single crystal surface as a function of oxidation temperature (300-1000 K) and oxygen exposure (up to 4500 l) by means of Auger electron spectroscopy, low-energy electron diffraction, ultraviolet photoelectron spectroscopy and high-resolution electron energy loss spectroscopy (HREELS). Both the surface composition and the surface structure of the resulting TiO(x) films exhibit a strong dependence on the preparation conditions. Loss of the chemical order and Ti segregation are observed at the Pt(3)Ti(111) surface upon oxygen exposures of more than 135 l at 1000 K. Increasing oxygen exposure enhances Ti segregation and oxide growth. At a threshold of ≈220 l (at 1000 K) a transition in the oxide structure occurs, namely from a (6 × 3√3) rectangular structure (a = 16.6 Å, b = 14.4 Å) below 220 l to a (7 × 7)R21.8° hexagonal structure (a = b = 19.3 Å) above 220 l. Two additional incommensurate rectangular metastable structures are observed for the highest oxygen exposures (above 900 l) at intermediate oxidation temperatures (800-900 K). In all cases the changes in the valence band spectra and the work function with respect to the clean Pt(3)Ti(111) surface are independent of the chosen oxidation parameters. Based on their HREELS spectra we identify the (6 × 3√3) and (7 × 7)R21.8° structures grown at 1000 K with a stoichiometric TiO phase, while the other and less stable oxide phases grown at 800-900 K exhibit more complex phonon structures that could not simply be associated with any of the stoichiometric phases TiO, Ti(2)O(3) or TiO(2). Our results are rather similar to those found by Granozzi et al for the deposition of Ti onto a Pt(111) surface in an oxygen atmosphere, except a few interesting deviations as a consequence of the different preparation conditions.
Authors:
Séverine Le Moal; Marco Moors; Jan Markus Essen; Christian Breinlich; Conrad Becker; Klaus Wandelt
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-04
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  25     ISSN:  1361-648X     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  -    
Other Details:
Languages:  ENG     Pagination:  045013     Citation Subset:  -    
Affiliation:
Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, D-53115 Bonn, Germany. Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris Sud, UMR 8182, F-91405 Orsay cedex, France.
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