| Autor: |
Scheiber, Philipp, Fidler, Martin, Dulub, Olga, Schmid, Michael, Diebold, Ulrike, Hou, Weiyi, Aschauer, Ulrich, Selloni, Annabella |
| Rok vydání: |
2018 |
| Předmět: |
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| Zdroj: |
Physical Review Letters, 109, 136103 (2012) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevLett.109.136103 |
| Popis: |
Anatase is a metastable polymorph of TiO$_2$. In contrast to the more widely-studied TiO$_2$ rutile, O vacancies (V$_\mathrm O$'s) are not stable at the anatase (101) surface. Low-temperature STM shows that surface V$_\mathrm O$'s, created by electron bombardment at 105 K, start migrating to subsurface sites at temperatures $\geq$ 200 K. After an initial decrease of the V$_\mathrm O$ density, a temperature-dependent dynamic equilibrium is established where V$_\mathrm O$'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, DFT 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. |
| Databáze: |
arXiv |
| Externí odkaz: |
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