TiO2, electron diffraction

Ti2O3-TiO2 (Ti O2 i) system, the shear operations of (121) [0il] and (132) [0il] are for 3 < n < 10 and 16 < n < 36, respectively. Between these compositions, i.e. between w = 10 and 16 (TiO 89 and TiOj 937), the shear planes seem to pivot around in a continuous manner from (121) to (132), which is unambiguously indicated in the electron diffraction patterns. A similar phenomenon has been observed in VjOg-TiOj, as shown below. 

Five samples with the nominal compositions shown in Table 2.8 were prepared by heating weighed mixtures of V2O3 and TiO2 in evacuated silica tubes at 1200 °C for 1-10 days. Electron diffraction patterns were taken for these samples, and the patterns on the [111] zone could be classified as Dj, D2, and Dj, as shown in Fig. 2.110. D, and D3 patterns come from the structures derived by the shear operations of (121) [0il] and (132) [O11], respectively. D2 patterns, on the other hand, show the arrays rotating between (121) and (132), which is very similar to the Ti O2 i system. Some of the examples with D2 patterns on the [111] zone axis are shown in Fig. 2.111. 

In Fig. 15a, O atoms would move to the right and Ti atoms to the left. The net effect of these displacement is to increase the effective coordination of the 5-fold coordinated Ti atoms [109]. To my knowledge, no experimental data on relaxations of the TiO2(100)(lxl) surface exist. X-ray photoelectron and Auger electron diffraction were performed but are insensitive to the details of the surface structure [111]. 

---