Titanate

In chemistry, titanate usually refers to inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

s composed of titanium oxides. In some cases, the term is used more generally for any titanium-containing anion, e.g. [TiCl₆]^2- and [Ti(CO)₇]^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, high-melting, and insoluble in water. They are often prepared at high temperatures, e.g. using tube furnace

Tube furnace

A tube furnace is an electric heating device used to conduct syntheses and purifications of inorganic compounds and occasionally in organic synthesis. The usual design consists of a cylindrical cavity surrounded by heating coils, which are embedded in a thermally insulating matrix. Temperature is...

s, from titanium dioxide. In virtually all cases, titanium achieves octahedral coordination geometry.

Orthotitanates

Orthotitanates have the formulae M₂TiO₄ where M is divalent. An example of such a material is the magnesium titanate (Mg₂TiO₄), which adopts the spinel

Spinel

Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4. Balas ruby is an old name for a rose-tinted variety.-Spinel group:...

 structure. Li₂TiO₃ is not considered a titanate since it adopts the rock-salt structure, and does not feature an identifiable titanium anion. Although orthotitanates almost never feature identifiable TiO₄^4- centres, the exception is Ba₂TiO₄.

Titanic acid and its esters

Also called orthotitanic acid or titanium hydroxide, the substance H₄TiO₄ (CASNo 20338-08-3) 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. 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 TiO₃^2- centres. They crystallize either in a hexagonal closest packing motif seen in corundum

Corundum

Corundum is a crystalline form of aluminium oxide with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red...

. This motif is illustrated by the commercially important mineral ilmenite

Ilmenite

Ilmenite is a weakly magnetic titanium-iron oxide mineral which is iron-black or steel-gray. It is a crystalline iron titanium oxide . It crystallizes in the trigonal system, and it has the same crystal structure as corundum and hematite....

 (FeTiO₃). Alternatively, some materials with the formula MTiO₃ crystallize in the motif known as Perovskite (structure), which is also the name of the mineral form of calcium titanate (CaTiO₃). Barium titanate

Barium titanate

Barium titanate is the inorganic compound with the chemical formula BaTiO3. Barium titanate is a white powder and transparent as larger crystals...

 is a ferroelectric peroviskite.

Complex titanates

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