LEED-IV study of the rutile $\mathrm{Ti}{\mathrm{O}}_2\left(110\right)\text{−}1\times 2$ surface with a Ti-interstitial added-row reconstruction

Upon sputtering and annealing in UHV at $\sim 1000\mathrm{K}$, the rutile $\mathrm{Ti}{\mathrm{O}}_2\left(110\right)$ surface undergoes a $1\times 1\to 1\times 2$ phase transition. The resulting $1\times 2$ surface is Ti rich, formed by strands of double Ti rows as seen on scanning tunneling microscopic images, but its detailed structure and composition have been subject to debate in the literature for years. Recently, Park et al. [Phys. Rev. Lett. 96, 226105 (2006)] have proposed a model where Ti atoms are located on interstitial sites with ${\mathrm{Ti}}_2\mathrm{O}$ stoichiometry. This model, when it is analyzed using LEED-IV data [Phys. Rev. Lett. 96, 0055502 (2006)], does 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 $1\times 2$ reconstruction. Therefore, the ${\mathrm{Ti}}_2{\mathrm{O}}_3$ added row is the preferred one from the point of view low-energy electron diffraction.

Figure 1

(Color online) Side and top views of the ball and stick model for the double-strand $\mathrm{Ti}\mathrm{O}\left(110\right)\text{−}1\times 2$ surface according to Park et al. (Ref. 12) with $\mathrm{Ti}{\left(ih\right)}_2\mathrm{O}$. Small (blue) balls (labeled by letters) represent Ti atoms, while large (red) balls (labeled by numbers) are O atoms. In the top view only top layer and reconstruction atoms are shown. Atomic positions have been allowed to relax to maximize the correlation between calculated LEED-IV curves for those models and the experimental ones. The best experiment-theory fit results in a Pendry $R$ factor $R_P=0.45$. The addition of O(1) rows [large yellow (light gray) balls] results in the $\mathrm{Ti}{\left(ih\right)}_2{\mathrm{O}}_3$ structure discussed in the text.

Figure 2

Experimental $I\left(V\right)$ curves (solid line) and calculated curves (dashed line) for the optimized geometry of Table .