Network-like (7v2 × v2)R45° surface reconstruction on rutile TiO2(001) by non-equilibrium self-organization

Year: 1999

Authors: Nörenberg H., Dinelli F., Briggs G.A.D.

Autors Affiliation: University of Oxford, Department of Materials, Parks Road, Oxford OX1 3PH, United Kingdom

Abstract: A self-organized network structure has been discovered after annealing TiO2(001) rutile single crystals under non-equilibrium conditions. This novel structure appears after annealing under ultrahigh vacuum conditions to above 1000°C and subsequent quenching at a rate of approx. 100°C s(-1). The surface structure was investigated by scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). We observed one-dimensional structures running along the [110] and [110] directions, thus forming a two-dimensional network of ridges separated by 4nm. From atomically resolved STM images and RHEED observations, a two-domain (7v2 × v2)R45° surface reconstruction is concluded. The network formation requires a massive rearrangement of atoms starting from the initially epi-polished surface, suggesting that kinetic processes play a crucial role in establishing the network structure. After further annealing to 1500-1600°C the structure remains but the ridges appear fragmented, presumably as result of stress which is induced by deformation of the crystal after high-temperature annealing. Several factors such as readily available oxygen diffusing from the bulk to the surface, titanium diffusing from the surface to the bulk and a high surface energy of the (001) surface of TiO2 seem to favour the appearance of the network structure.

Journal/Review: SURFACE SCIENCE

Volume: 436 (1-3)      Pages from: L635  to: L640

KeyWords: Scanning tunnelling microscopy (STM); Self-organization; Surface reconstruction; Titanium dioxide (Tio2)
DOI: 10.1016/S0039-6028(99)00718-9

Citations: 28
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