aluminate

Aluminate is a broad term in inorganic chemistry for compounds that contain aluminum in association with oxygen and/or hydroxide, often as salts of aluminic acid or as oxide/hydroxide networks. The name comes from aluminum and the -ate suffix, indicating a derivative of aluminic acid or an oxyanion of aluminum.

In aqueous solution the principal aluminate species is the tetrahydroxoaluminate anion, [Al(OH)4]−, formed when aluminum dissolves in strong base. Solid aluminates include sodium aluminate NaAlO2 and calcium aluminate CaAl2O4, which are used in cement chemistry and materials processing.

Calcium aluminates are key components of high-alumina cements, contributing rapid strength gain and heat resistance. Sodium aluminate is used as a coagulant in water treatment and as a precursor in various chemical syntheses.

Aluminate compounds can be prepared by reacting aluminum sources with alkali or hydroxide bases, or by high-temperature solid-state reactions between aluminum oxide and alkaline earth oxides. In solution, they tend to hydrolyze to aluminum hydroxide upon acidification.

Because of their ease of hydrolysis and strong Al–O interactions, aluminates are encountered in ceramics, cements, and various industrial processes. The term also covers related aluminates in which aluminum is part of oxide lattices or complex ions.