In chemistry, titanate
usually refers to 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
. 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
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 have the formulae M2
where M is divalent. An example of such a material is the magnesium titanate (Mg2
), which adopts the 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:...
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 TiO44-
centres, the exception is Ba2
Titanic acid and its esters
Also called orthotitanic acid or titanium hydroxide, the substance H4
(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
. It is a weak acid, if it can be isolated.
The metatitanates have the formula MTiO3
, where again M is divalent. They do not feature discrete TiO32-
centres. They crystallize either in a hexagonal closest packing motif seen in 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 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....
). 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 is the inorganic compound with the chemical formula BaTiO3. Barium titanate is a white powder and transparent as larger crystals...
is a ferroelectric peroviskite.
More complex titanates are also known, such as bismuth titanate, Bi4