Upon sputtering and annealing in ultra-high vacuum at ~1000K, the rutile TiO2(110) surface underwent a 1 x 1 →1 x 2 phase transition. The resulting 1 x 2 surface was Ti rich, formed by strands of double Ti rows as seen on scanning tunnelling microscopic images, but its detailed structure and composition were subject to debate in the literature for years. Park et alia (2006) had proposed a model in which Ti atoms were located on interstitial sites with Ti2O stoichiometry. This model, when it was analyzed using low-energy electron diffraction-IV data did not yield an agreement between theory and experiment as good as the previous best fit for Onishi and Iwasawa's model for the long-range 1 x 2 reconstruction. Therefore, the Ti2O3 added row was the preferred one from the point of view low-energy electron diffraction.

LEED-IV Study of the Rutile TiO2(110)-1 x 2 Surface with a Ti-Interstitial Added-Row Reconstruction. Blanco-Rey, M., Abad, J., Rogero, C., Méndez, J., López, M.F., Román, E., Martín-Gago, J.A., de Andrés, P.L.: Physical Review B, 2007, 75[8], 081402