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Titanium dioxide

News about Titanium dioxide



Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. It has a wide range of applications, from paint to sunscreen to food colouring. When used as a food colouring, it has E number E171.

Occurance
Titanium dioxide occurs in nature as well-known minerals rutile, anatase and brookite, and additionally as two high pressure forms, a monoclinic baddeleyite-like form and an orthorhombic α-PbO2-like form, both found recently at the Ries crater in Bavaria.[1][2] The most common form is rutile,[3] which is also the most stable form. Anatase and brookite both convert to rutile upon heating.[3] Rutile, anatase and brookite all contain six coordinated titanium.

Titanium dioxide has eight modifications - in addition to rutile, anatase and brookite there are three metastable forms produced synthetically (monoclinic, tetragonal and orthorombic), and five high pressure forms (α-PbO2-like, baddeleyite-like and cotunnite-like):

Applications
PigmentTitanium dioxide is the most widely used white pigment because of its brightness and very high refractive index (n = 2.7), in which it is surpassed only by a few other materials. Approximately 4 million tons of pigmentary TiO2 are consumed annually worldwide. When deposited as a thin film, its refractive index and colour make it an excellent reflective optical coating for dielectric mirrors and some gemstones like "mystic fire topaz". TiO2 is also an effective opacifier in powder form, where it is employed as a pigment to provide whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, medicines (i.e. pills and tablets) as well as most toothpastes. In paint, it is often referred to offhandedly as "the perfect white", "the whitest white", or other similar terms. Opacity is improved by optimal sizing of the titanium dioxide particles.

In ceramic glazes titanium dioxide acts as an opacifier and seeds crystal formation.

Titanium dioxide is often used to whiten skimmed milk; this has been shown statistically to increase skimmed milk's palatability.[17]

Titanium dioxide is used to mark the white lines on the tennis courts of the All England Lawn Tennis and Croquet Club, best known as the venue for the annual grand slam tennis tournament The Championships, Wimbledon.[18]