(Sub)Surface mobility of oxygen vacancies at the TiO 2 anatase (101) surface

Philipp Scheiber, Martin Fidler, Olga Dulub, Michael Schmid, Ulrike Diebold, Weiyi Hou, Ulrich Aschauer, Annabella Selloni

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Abstract

Anatase is a metastable polymorph of TiO 2. In contrast to the more widely studied TiO 2 rutile, O vacancies (V O's) are not stable at the anatase (101) surface. Low-temperature STM shows that surface V O's, created by electron bombardment at 105K, start migrating to subsurface sites at temperatures 200K. After an initial decrease of the V O density, a temperature-dependent dynamic equilibrium is established where V O's move to subsurface sites and back again, as seen in time-lapse STM images. We estimate that activation energies for subsurface migration lie between 0.6 and 1.2eV; in comparison, density functional theory calculations predict a barrier of ca. 0.75eV. The wide scatter of the experimental values might be attributed to inhomogeneously distributed subsurface defects in the reduced sample.

Original languageEnglish (US)
Article number136103
JournalPhysical review letters
Volume109
Issue number13
DOIs
StatePublished - Sep 28 2012

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Scheiber, P., Fidler, M., Dulub, O., Schmid, M., Diebold, U., Hou, W., Aschauer, U., & Selloni, A. (2012). (Sub)Surface mobility of oxygen vacancies at the TiO 2 anatase (101) surface. Physical review letters, 109(13), [136103]. https://doi.org/10.1103/PhysRevLett.109.136103