Titanium rutile, synthesis

Tomita K, Petrykin V, Kobayashi M, Shiro M, Yoshimura M, Kakihana MA (2006) Water-soluble titanium complex for the selective synthesis of nanocrystaUine brookite, rutile, and anatase by a hydrothermal method. Angew Chem Int Edit 118 2438-2441... 

Titanium (IV) oxide crystallizes In three modifications of decreasing stability rutile, anatase and brookite. Whether the synthesis of brookite has been achieved is still in doubt. Anatase is formed via the hydrolysis of Ti halides at not too high a temperature (600°C) or via low-temperature calcining ( 700°C) of precipitated titanic acid. The lattice is stabilized by adsorbed anions, among which the most effective are sulfate and phosphate. Pure TiOg calcined at high temperature always yields the rutile lattice. 

The synthesis of pure rutile is difficult, as the crystallization normally yields mixtures of two, or even all three, polymorphs. Rutile is usually prepared via a hydrothermal synthesis from chlorides and oxychlorides of titanium seeded with rutile nanocrystals at temperatures below 250 °C. The addition of hydrochloric acid and aqueous alcohol solutions facilitates the preparation of rutile at temperatures between 40 and 90 °C [148]. Despite the risk of contamination, mineralizers (e.g., Sn02, NH4CI or N aCl) are often used in order to reduce the size of rutile crystals. The reaction times of the hydrothermal synthesis of rutile can be significantly reduced by microwave irradiation [149]. A single-phase rutile with nanosized, well-dispersed particles prepared by a 2 h treatment of partially hydrolyzed 0.5 M TiCU solution at 160 °C is shown in Figure 1.9. 

N.J. Marston, B. Vincent, N.G. Wright, The synthesis of spherical rutile titanium dioxide particles and their interaction with polystyrene latex particles of opposite charge. Prog. Colloid Polym. Sci. 1998, 109, 278-282. 

Titanium oxide nanostructures have versatile applications, for example, in photocatalysis, solar-energy conversion, sensors, and ductile ceramics. The synthesis of derivatives with all kinds of size and shape (spherical particles, nanotubes, and nanorods) has been described in numerous studies. Out of the three main titanium polymorphs (anatase, brookite, rutile), research so far has been centred on the synthesis of anatase nanoparticles. However, recently the generation of nanometer-sized rutile has received growing attention due to its promising potential as a photocatalyst and as an electrode material. 

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