Mesostructured titania films

Usually, in the fabrication of mesostructured titania films by sol-gel templating, anatase, the kinetically more stable phase, is formed independent of the Ti precursor and template. Phase transformation of anatase to rutile occurs only upon heating to high temperature which however leads to collapse of the ordered mesoporous structure. 

Figure 29.3 TEM micrographs of mesostructured titania films calcined at 550°C (a) and 400°C (b). The inset is a small-angle electron diffraction pattern from a selected area. (Parts (a and b) are reprinted with permission from Refs [60,63], respectively.)...

Alberius, P. C. A. Frindell, K. L. Hayward, R. C. Kramer, E. J. Stucky, G. D. Chmelka, B. F. 2002. General predictive syntheses of cubic, hexagonal, and lamellar silica and titania mesostructured thin films. Chem. Mater. 14 3284-3294. 

Malfatti, L. Falcaro, P Amenitsch, H. Caramori, S. Argazzi, R. Bignozzi, C. A. Enzo, S. Maggini, M. Innocenzi, P. 2006. Mesostructured self-assembled titania films for photovoltaic applications. Microporous Mesoporous Mater. 88 304-311. 

The transmittance spectrum of a titania nanotube-film (transparent) on glass is shown in Fig. 5.33. The optical behavior of the Ti02 nanotube-arrays is quite similar to that reported for mesostructured titanium dioxide [133], The difference in the envelope-magnitude encompassing the interference fringe maxima and minima is relatively small compared to that observed in titania films deposited by rf sputtering, e-beam and sol-gel methods [134],... 

PC.A. Alberius, K.L. Frindell, R.C. Hayward, E.J. Kramer, G.D. Stucky, and B.F. Chmelka, General Predictive Syntheses of Cubic, Hexagonal, and Lamellar Silica and Titania Mesostructured Thin Films. Chem. Mater., 2002, 14, 3284—3294. 

The type of mesostructure obtained depends strongly on the surfactant to inorganic ratio. In fact, there is a close correlation between the surfactant to solvent ratio in the phase diagram of a surfactant and the surfactant to inorganic ratio in the mesostructured materials obtained. Alberius et al. demonstrated this correlation by the so-called general predictive synthesis approach. They used the phase diagrams of the water-surfactant system to guide the synthesis of mesoporous silica and titania films. There was a very close correlation between the values of the volume fraction of the surfactant over which different phases are obtained in the water-surfactant system and in the silica-surfactant and titania-surfactant systems. 

Bass, J.D., Grosso, D., Boissiere, C, and Sanchez, C. (2008) Pyrolysis, crystallization, and sintering of mesostructured titania thin films assessed by in situ thermal ellipsometry. /. Am. 

Crepaldi, E.L., G. Soler-Illia, D. Grosso, F. Cagnol, F. Ribot and C. Sanchez (2003). Controlled formation of highly organized mesoporous titania thin films From mesostructured hybrids to mesoporous nanoanatase Ti02. Journal of the American Chemical Society, 125(32),... 

Figure 35.4. Schematic pathway to mesostructured silica / titania mixed oxide films.

Crepaldi E.L., de A.A. Soler-IUia G.J., Grosso D., Sanchez C. Nanocrystallised titania and zirconia mesoporous thin films exhibiting enhanced thermal stabtiity. New J. Chem. 2003b 27 9-13 Crepaldi E.L., Grosso D., de A.A. Soler-IlUa G.J., Albouy P.-A., Amenitsch H., Sanchez C. Formation and stabilization of mesostructured vanadium-oxo-based hybrid thin films. Chem. Mater. 2002 14 3316-3325... 

Hilsing N., Launay B., Doshi D., Kickelbick G. Mesostructured silica-titania mixed oxide thin films. Chem. Mater. 2002 14 2429-2432... 

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