TiO2 rutile

Figure 2.1 shows the X-ray powder diffraction patterns (CuK ) of compounds TiO, between TijO, (x = 1.5) and TiO2 (x = 2.0). This clearly indicates the convergence of the diffraction patterns to that of TiO2 (rutile) with increasing x, which is why the Magneli school predicted the mother... 

Operation (7) The mother structure (for example, TiO2 (rutile)) is divided into blocks with the dimension of a = x (n is an integer), where is a shear plane with plane indices (hkl) and is the plane spacing of H. (Fig. 2.2(a)). 

Ishibashi, T, Uetsuka, H. and Onishi, H. (2004) An ordered retinoate monolayer prepared on rutile TiO2(110)./. Phys. Chem. B, 108, 17166-17170. 

According to this rule, rutile and, at high pressures, the modification with the cz-PbO2 structure are the most stable forms of TiO2. Numerous compounds crystallize in the rutile type and some in the a-PbO2 type, whereas scarcely any examples are known for the brookite and the anatase structures. 

Next, the rutile (TiO2) based shear structure is discussed. In the rutile-type structure (tetragonal), the metal and oxygen occupy the following positions as shown in Fig. 2.8 ... 

Carefully prepared Au catalysts have a relatively narrow particle size distribution, giving mean diameters in the range 2-10 nm with a standard deviation of about 30%. A major reason why Au particles remain as NPs even after calcination 573 K is the epitaxial contact of Au NPs with the metal oxide supports. Gold particles always expose its most densely packed plane, the (111) plane, in contact with a-Fe2O3(110), Co304(lll), anatase Ti02(112), and rutile TiO2(110). 

Materials. The titanium dioxide powders were rutile in structure (obtained from the Titanium Division, National Lead Co., Amboy, N. J.), with nominal specific surface areas of 10 and of 100 sq. meters per gram. Chemical analysis by the supplier showed negligible impurities except for 0.8% sodium oxide in the Ti02-100 and traces of iron in both the TiO2-10 and the TiO2-100. The presence of iron was confirmed by the nature of the decay of the neutron irradiation—induced radioactivities. 

Fig. 8.20. (a) Densities of states of the surface clusters (Ti40,5) (solid line) and (Ti40i6)" (dashed line) calculated by the DV-Za method, (b) Densities of states of the clusters (Ti30,4) (solid line) and (TijO,) - (dashed line) representative of solid bulk TiOj calculated by the DV-Za method, (c) Ultraviolet photoelectron spectra for the ordered (dashed line) and bombarded (solid line) (110) surface of rutile (TIO2) (after Tsukada et al., 1983 reproduced with the publisher s permission). 

Figure 1.9. Adsorption of water on rutile (TIO2). (Redrawn from A.C. Zettlemoyer, F.J. Micale and K. Klier, in Water, a Comprehensive Treatise, F. Franks. Ed., Plenum Press (1974). ch. 5.)...

Fig. 9 Electron transfer per bond A as a function of the difference SV ad in the Madelung potentials (in Hartree per electron) acting on the Ti and O in neutral stoichiometric clusters (filled circles), in bulk rutile Ti02 (plus), and on the TiO2(110) surface (diamonds) (from Ref. 243).

It was shown in Ref. 243, devoted to a study of Ti Om clusters, TiO2(110) surface and bulk rutile Ti02, that, although the AojCj S e not measurable quantities, their variations are strongly and systematically correlated to variations of bond-lengths (Fig. 10). They are thus pertinent quantities to discuss modifications of the iono-covalent character at surfaces. 

Only a few oxide surfaces have been quantitatively investigated by GIXS among them the surfaces of sapphire a-Al203(0001), MgO(OOl), rutile TiO2(110), NiO(lll), ZnO(OOOl) -O and -Zn, CrzOaCOOOl), SrTiOjCOOl). The... 

Fig. 16. Surface termination of the rutile TiO2(001) surface. Only one possibility exists to cut a Ti02 crystal in this direction, see the side view at the left side. Surface Ti atoms are 4-fold coordinated and surface O atoms 2-fold coordinated.

It is comforting that the elemental rules for predicting surface terminations outlined in section 3.1.1. work so well for predicting the structure of the (1x1) terraces and the step edges of all the orientations of both rutile and anatase. The extensive theoretical work has helped to refine the understanding of surface relaxations, and the level of detail on the atomic geometry of the TiO2(110) surface is certainly comparable to that of certain elemental semiconductors or metals. 

Photoreactions of organic compounds over model surfaces of wide band-gap oxide semiconductors have received considerable attention recently [43, 79-82]. The most-studied photocatalytic reactions on rutile TiO lllO) single-crystal surfaces include ethanol [43], acetic acid [78], trimethyl acetic acid [80, 81], and acetone [82]. In this section, we will focus on the photoreaction of ethanol over TiOj(llO). Ethanol is dissociatively adsorbed via its oxygen lone pair on fivefold coordinated Ti atoms to produce adsorbed ethoxide species (Fig. 7.6). STM studies of the adsorption of ethanol on TiO2(110) demonstrated the presence of both alkoxides and surface hydroxyls [83] confirming the adsorption is dissociative. Figure 7.11 is the XPS Cls spectra after the exposure of ethanol (9=0.5 with respect to Ti atoms). 

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