Titanium dioxide films

Rutile possesses a high refractive index, thus making it an ideal material for passive optical wave-guides [17, 18]. Many of the mentioned applications forTi02 require the employment of thin films. CVD techniques have been used widely for the fabrication of such films. Titanium dioxide films have been prepared by the hydrolysis of TiCU [19, 20], by the reaction of TiCU with oxygen [21] and by the decomposition of titanium alkoxides, Ti(OR)4 (R = alkyl), under an atmosphere of oxygen [14, 15, 17, 18, 22]. Anastase-type SniTii 02 solid solutions have been prepared from the CVD of a mixture of TiCU and SnCU in the presence of water at 630°C [23]. 

Thermolysis is used in the coating of glass and other surfaces with a film of titanium dioxide. When a lower alkoxide, eg, TYZOR TPT, vaporizes in a stream of dry air and is blown onto hot glass botdes above ca 500°C, a thin, transparent protective coating of Ti02 is deposited. 

Some of the chemicals mentioned above and others, such as chlorinated mbber or paraffin, antimony trioxide, calcium carbonate, calcium borate, pentaerythrithol, alumina trihydrate, titanium dioxide, and urea—melamine—formaldehyde resin, may be used to formulate fire retardant coatings. Many of these coatings are formulated in such a way that the films intumesce (expand) when exposed to fire, thus insulating the wood surface from further thermal exposure. Fire retardant coatings are mostly used for existing constmction. 

Chemical vapour deposition Example. The preparation of films of titanium dioxide. 

General Titanium is intrinsically very reactive, so that whenever the metal surface is exposed to air, or to any environment containing available oxygen, a thin tenacious surface film of oxide is formed. This oxide, which is present on fabricated titanium surfaces at normal or slightly elevated temperatures, has been identified as rutile, a tetragonal form of titanium dioxide, and it is the presence of this surface film which confers upon titanium excellent corrosion resistance in a wide range of corrosive media. 

Quite recently (2001) titanium dioxide has been used to coat "self-cleaning" windows with a very thin film about 5 x 10-6 cm thick. The titanium dioxide acts as a catalyst for the decomposition of dust and grime by solar ultraviolet light. Probably more important, it lowers surface tension so that rain water "sheets down" the window, washing away dirt. 

F. Hide, B.J. Schwartz, M. A. Diaz-Garcia, A.J. Hceger, Laser emission from solutions and films containing semiconducting polymer and titanium dioxide naiioerysials. Chem. Phys. Lett. 1996, 256, 424. 

Nanoparticles of the semicondnctor titanium dioxide have also been spread as mono-layers [164]. Nanoparticles of TiOi were formed by the arrested hydrolysis of titanium iso-propoxide. A very small amount of water was mixed with a chloroform/isopropanol solution of titanium isopropoxide with the surfactant hexadecyltrimethylammonium bromide (CTAB) and a catalyst. The particles produced were 1.8-2.2 nm in diameter. The stabilized particles were spread as monolayers. Successive cycles of II-A isotherms exhibited smaller areas for the initial pressnre rise, attributed to dissolution of excess surfactant into the subphase. And BAM observation showed the solid state of the films at 50 mN m was featureless and bright collapse then appeared as a series of stripes across the image. The area per particle determined from the isotherms decreased when sols were subjected to a heat treatment prior to spreading. This effect was believed to arise from a modification to the particle surface that made surfactant adsorption less favorable. 

Phillips, L.G. and Barbano, D.M., The influence of fat substitutes based on protein and titanium dioxide on the properties of low fat milks, J. Dairy Sci., 80, 2726, 1997. Choi, J.Y. et ah, Photocatalytic antibacterial effect of TiOj film formed on Ti and TiAg. J. Biomed. Mater. Res. B Appl. Biomater., epub., 2006. 

Lindgren, T., Mwabora, J.M., Avendano, E., Jonsson, J., Hoel, A., Granqvist, C.G., and Lindquist, S.-E., Photoelectrochemical and optical properties of nitrogen doped titanium dioxide films prepared by reactive DC magnetron sputtering, /. Phys. Chem. B, 107, 5709, 2003. 

Kale, S. S. Mane, R. S. Chung, H. Yoon, M.-Y. Lokhande, C. D. Han, S.-H. 2006. Use of successive ionic layer adsorption and reaction (SILAR) method for amorphous titanium dioxide thin films growth. Appl. Surf. Sci. 253 421 424. 

D.H. Kim, M.A. Anderson, Photo-electrocatalytic degradation of formic acid using a porous titanium dioxide fhin-film electrode, Environ. Sci. Technol. 28 (1994) 479-483. 

K. Hashimoto, Visible-light induced hydrophilicity on nitrogen-substituted titanium dioxide films, Chem. Commun. (2003) 1298-1299. 

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