When reduced TiO2(110) single crystals were oxidized at moderate temperatures (470 to 660K), the surfaces restructure. Interstitial Ti atoms from the bulk diffuse to the surface where they react with gaseous oxygen and form new, added TiO2 layers. These were characterized by three structural elements: small (1x1) islands, irregular networks of pseudohexagonal rosettes, and [001]-oriented strands. The strands exhibit the same structural characteristics as the (1x2) surface reconstruction, which forms upon annealing at higher temperatures. Atomic-resolution scanning tunnelling microscopy images of the strands were consistent with the added-Ti2O3-row model. UHV annealing of oxygen-restructured surfaces smoothed the surfaces and converts the rosette networks into strands and finally into regular (1x1) terraces. The composition of these oxygen-induced phases was quantified using 18O2 gas in combination with low-energy He+ ion scattering measurements. Dynamic processes for the conversion from rosette networks into (1x2) strands and ultimately into (1x1) terraces were discussed.

Morphology Change of Oxygen-Restructured TiO2 (110) Surfaces by UHV Annealing: Formation of a Low-Temperature (1x2) Structure. Li, M., Hebenstreit, W., Diebold, U.: Physical Review B, 2000, 61[7], 4926-33