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Ionics

pp 1–10 | Cite as

Chromium segregation in Cr-doped TiO2 (rutile): impact of oxygen activity

  • Kazi A. Rahman
  • N. Sharma
  • A. J. Atanacio
  • T. Bak
  • E. D. Wachsman
  • M. Moffitt
  • J. NowotnyEmail author
Original Paper
  • 49 Downloads

Abstract

This work considers the effect of chromium surface segregation for polycrystalline Cr-doped TiO2 on surface vs. bulk defect disorder. It is shown that annealing of Cr-doped TiO2 (0.04 at% Cr) in the gas phase of variable oxygen activity at 1273 K results in a gradual transition in the valence of chromium at the surface from predominantly Cr3+ species in reduced conditions, p(O2) = 10−12 Pa, to comparable concentrations of both Cr3+ and Cr6+ species in oxidising conditions, p(O2) = 105 Pa. The reported data is considered in terms of defect equilibria leading to the formation of positively and negatively charged chromium in both the cation sub-lattice and interstitial sites. The derived theoretical models represent the effect of oxygen activity on the surface charge and the resulting electric field leading to migration mechanism of charged chromium species.

Keywords

Titanium dioxide Cr-doped TiO2 Segregation Oxygen activity XPS 

Notes

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Kazi A. Rahman
    • 1
  • N. Sharma
    • 2
  • A. J. Atanacio
    • 3
  • T. Bak
    • 1
  • E. D. Wachsman
    • 4
  • M. Moffitt
    • 5
  • J. Nowotny
    • 1
    Email author
  1. 1.Solar Energy TechnologiesWestern Sydney UniversityPenrithAustralia
  2. 2.School of ChemistryUniversity of New South WalesSydneyAustralia
  3. 3.Centre for Accelerator ScienceAustralian Nuclear Science and Technology OrganisationKirrawee DCAustralia
  4. 4.Maryland Energy Innovation InstituteUniversity of MarylandCollege ParkUSA
  5. 5.School of Science and HealthWestern Sydney UniversityPenrithAustralia

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