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Titanium dioxide, also known as titanium(IV) oxide or titania / t aɪ ˈ t eɪ n i ə /, is the inorganic compound derived from titanium with the chemical formula TiO 2. When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. [4] It is a white solid that is insoluble in water, although mineral forms can appear ...
Brookite is the orthorhombic variant of titanium dioxide (TiO 2), which occurs in four known natural polymorphic forms (minerals with the same composition but different structure). The other three of these forms are akaogiite ( monoclinic ), anatase ( tetragonal ) and rutile ( tetragonal ).
Akaogiite (IMA symbol Aka [1]) is an exceedingly rare mineral, one of the natural forms of titanium dioxide (TiO 2). It is a high-pressure polymorph of TiO 2, along with anatase, brookite and another high-pressure phase called "TiO 2 II". [2] [3] [4] Rutile is the stable polymorph of TiO 2, most commonly found at standard temperatures and ...
Anatase is metastable at all temperatures and pressures, with rutile being the equilibrium polymorph. Nevertheless, anatase is often the first titanium dioxide phase to form in many processes due to its lower surface energy, with a transformation to rutile taking place at elevated temperatures. [7]
Rutile is an oxide mineral composed of titanium dioxide (TiO 2), the most common natural form of TiO 2. Rarer polymorphs of TiO 2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high ...
Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure."
Via the Kroll process, TiCl 4 is used in the conversion of titanium ores to titanium metal. Titanium tetrachloride is also used to make titanium dioxide, e.g., for use in white paint. [19] It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation. [20]
Reidite, the high-pressure scheelite-structure polymorph of zircon, is known only from impact structures. Shatter cones developed in fine grained dolomite from the Wells Creek crater , USA. Two of the high-pressure polymorphs of titanium dioxide , one with a baddeleyite -like form and the other with a α-PbO 2 structure, have been found ...