Physical Review Letters · 2012 · 208 citations · 25 references
Natural SciencesMaterials EngineeringMaterials SciencePhysical ChemistrySurface ChemistrySurface ScienceNucleationSurface KineticsSurface OxidationSurface Phase TransitionsSurface PhysicsSurface ThermodynamicsOxide Growth KineticsOxide NucleationOxygen VacanciesOxygen Vacancies In Metal OxidesOxygen Vacancy ChemistryOxygen Vacancy FormationSurface Oxidation MechanismsSurface Vacancy Diffusion
Anatase is a metastable polymorph of TiO2. In contrast to the more widely studied TiO2 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 105 K, start migrating to subsurface sites at temperatures ≥200 K. 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 1.2 eV; in comparison, density functional theory calculations predict a barrier of ca. 0.75 eV. The wide scatter of the experimental values might be attributed to inhomogeneously distributed subsurface defects in the reduced sample.
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The surface science of titanium dioxide
Ulrike Diebold · Surface Science Reports · 2003 · 7.8K citations
Natural Sciences, Materials Engineering, Materials Science +14