Aluminium diboride (AlB2) is a chemical compound made from the metal aluminium and the metalloid boron.It is a red solid under normal temperature and pressure. It loses its surface luster when heated, and is stable in cold dilute acid. It is decomposed in hot hydrochloric acid and nitric acid. It is one of two compounds of aluminium and boron, the other being AlB12, which are both commonly referred to as aluminium boride. AlB12 is black and glossy monoclinal crystal, specific gravity 2.55(18℃), insoluble in water, acid, alkali, decomposition in hot nitric acid,It is obtained by melting boron trioxide, sulfur and aluminum together.
Molar mass:48.604 g/mol
Density 3.19 g/cm3
Melting point:>920 °C (decomposes)
Solubility in water: insoluble
Structurally the B atoms form graphite-like sheets with Al atoms between them, and this is very similar to the structure of magnesium diboride. Single crystals of AlB2 exhibit metallic conductivity along the axis parallel to the basal hexagonal plane.
Aluminium boride is considered a hazardous substance as it reacts with acids and hydrogen gas to produce toxic gases.