In chemistry, titanate usually refers to

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemi ...

s composed of

titanium oxide Titanium oxide may refer to: * Titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), o ...

s. Together with niobate, titanate salts form the Perovskite group. In some cases, the term is used more generally for any titanium-containing

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

, e.g. iCl₆sup>2− and i(CO)₆sup>2−. This article focuses on the oxides. Many kinds of titanium oxides are known, and some are commercially important. Typically these materials are white,

diamagnetic Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted ...

, high-melting, and insoluble in water. They are often prepared at high temperatures, e.g. using tube furnaces, from titanium dioxide. In virtually all cases, titanium achieves octahedral coordination geometry..

Orthotitanates

Orthotitanates have the formula M₂TiO₄, where M is divalent. An example of such a material is magnesium titanate (Mg₂TiO₄), which adopts the spinel structure. Li₂TiO₃ is not considered an orthotitanate since it adopts the

rock-salt structure Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

and does not feature an identifiable titanium anion. Orthotitanates almost never feature identifiable TiO₄⁴⁻ centres, an exception being Ba₂TiO₄.

Titanic acid and its esters

Also called orthotitanic acid or titanium hydroxide, the substance H₄TiO₄ is called titanic acid. This material, which is not well defined, is obtained by hydrolysis of TiCl₄. The solid is unstable with respect to loss of water and formation of titanium dioxide. Esters of orthotitanic acid are known, however; one example being titanium isopropoxide. Esters derived from smaller alcohols adopt more complex structures wherein titanium does achieve octahedral coordination, e.g. Ti₄(OCH₃)₁₆ or titanium tetramethoxide. It is a weak acid, if it can be isolated.

Metatitanates

The metatitanates have the formula MTiO₃, where again M is divalent. They do not feature discrete TiO₃²⁻ centres. Some, like the commercially important mineral

ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...

(FeTiO₃), crystallize in the hexagonal close packing motif seen in

corundum Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the ...

. Alternatively, some materials with the formula MTiO₃ crystallize in the motif known as

perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure In crystallography, crystal ...

, which is also the name of the mineral form of

calcium titanate Calcium titanate is an inorganic compound with the chemical formula Ca Ti O3. As a mineral, it is called perovskite, named after Russian mineralogist, L. A. Perovski (1792-1856). It is a colourless, diamagnetic solid, although the mineral is of ...

(CaTiO₃). Barium titanate is one such perovskite-structured titanate with ferroelectric properties.

Complex titanates

More complex titanates are also known, such as bismuth titanate, Bi₄Ti₃O₁₂..

References

{{Titanium compounds Transition metal oxyanions Oxometallates