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Title: The influence of the bulk reduction state on the surface structure and morphology of rutile TiO{sub 2}(110) single crystals

Abstract

The authors have investigated the relationship between different types and amounts of bulk defects and the surface morphology of TiO{sub 2}(110) single crystals prepared by annealing in ultrahigh vacuum and in oxygen. Rutile TiO{sub 2}(110) specimens were cut from the same crystal and were heated in a furnace to different temperatures which resulted in different states of reduction (colors of the crystals). After characterization of the bulk defects with electron paramagnetic resonance (EPR), the specimens were studied with scanning tunneling microscopy (STM), low-energy He{sup +} ion scattering (LEIS), and work function measurements. EPR reveals that darker rutile crystals exhibit higher concentrations of extended Ti{sup 3+} related bulk defects such as crystallographic shear planes (CSP), with a decrease in substitutional and interstitial defects as compared to lighter crystals. Surface structures with (1 x 2) features are preferably formed upon UHV annealing on these darker crystals. LEIS measurements show that all of the crystals' (110) surfaces are reoxidized upon annealing in {sup 18}O{sub 2} (573 K, 1 x 10{sup {minus}6} mbar, 10 min) and that the {sup 18}O surface content is proportional to the bulk reduction state. UV-visible adsorption spectra and resistivity measurements also scale with the reduction states of crystals. Onlymore » the (1 x 1) structure is observed on the surface of slightly reduced crystals. Annealing in oxygen induces additional metastable structures, i.e., TiO{sub 2} clusters on blue crystals and rosette networks on dark blue crystals.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Tulane Univ., New Orleans, LA (US)
Sponsoring Org.:
National Science Foundation (NSF); USDOE
OSTI Identifier:
20075921
DOE Contract Number:  
AC06-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 104; Journal Issue: 20; Other Information: PBD: 25 May 2000; Journal ID: ISSN 1089-5647
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TITANIUM OXIDES; MORPHOLOGY; SURFACE PROPERTIES; DEFECTS; VALENCE; MONOCRYSTALS

Citation Formats

Li, M., Hebenstreit, W., Diebold, U., Tyryshkin, A.M., Bowman, M.K., Dunham, G.G., and Henderson, M.A. The influence of the bulk reduction state on the surface structure and morphology of rutile TiO{sub 2}(110) single crystals. United States: N. p., 2000. Web. doi:10.1021/jp9943272.
Li, M., Hebenstreit, W., Diebold, U., Tyryshkin, A.M., Bowman, M.K., Dunham, G.G., & Henderson, M.A. The influence of the bulk reduction state on the surface structure and morphology of rutile TiO{sub 2}(110) single crystals. United States. doi:10.1021/jp9943272.
Li, M., Hebenstreit, W., Diebold, U., Tyryshkin, A.M., Bowman, M.K., Dunham, G.G., and Henderson, M.A. Thu . "The influence of the bulk reduction state on the surface structure and morphology of rutile TiO{sub 2}(110) single crystals". United States. doi:10.1021/jp9943272.
@article{osti_20075921,
title = {The influence of the bulk reduction state on the surface structure and morphology of rutile TiO{sub 2}(110) single crystals},
author = {Li, M. and Hebenstreit, W. and Diebold, U. and Tyryshkin, A.M. and Bowman, M.K. and Dunham, G.G. and Henderson, M.A.},
abstractNote = {The authors have investigated the relationship between different types and amounts of bulk defects and the surface morphology of TiO{sub 2}(110) single crystals prepared by annealing in ultrahigh vacuum and in oxygen. Rutile TiO{sub 2}(110) specimens were cut from the same crystal and were heated in a furnace to different temperatures which resulted in different states of reduction (colors of the crystals). After characterization of the bulk defects with electron paramagnetic resonance (EPR), the specimens were studied with scanning tunneling microscopy (STM), low-energy He{sup +} ion scattering (LEIS), and work function measurements. EPR reveals that darker rutile crystals exhibit higher concentrations of extended Ti{sup 3+} related bulk defects such as crystallographic shear planes (CSP), with a decrease in substitutional and interstitial defects as compared to lighter crystals. Surface structures with (1 x 2) features are preferably formed upon UHV annealing on these darker crystals. LEIS measurements show that all of the crystals' (110) surfaces are reoxidized upon annealing in {sup 18}O{sub 2} (573 K, 1 x 10{sup {minus}6} mbar, 10 min) and that the {sup 18}O surface content is proportional to the bulk reduction state. UV-visible adsorption spectra and resistivity measurements also scale with the reduction states of crystals. Only the (1 x 1) structure is observed on the surface of slightly reduced crystals. Annealing in oxygen induces additional metastable structures, i.e., TiO{sub 2} clusters on blue crystals and rosette networks on dark blue crystals.},
doi = {10.1021/jp9943272},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
issn = {1089-5647},
number = 20,
volume = 104,
place = {United States},
year = {2000},
month = {5}
}