Black Antimony Allotrope

Antimony’s three unstable allotropes are black, yellow, and explosive. An allotrope is a variation of the molecular structure of a single element. Differences in chemical structure will give an element different physical properties depending on the allotropic form. For example, carbon has two common allotropes; diamond and graphite. In the diamond form the carbon atoms are arranged in a tetrahedral lattice configuration. In the graphite form, on the other hand, carbon atoms are bonded in layers of a hexagonal lattice.

Black antimony is an amorphous black powder, with a specific gravity of 5.3. It can be obtained when metallic antimony vapor is shock cooled or when liquid antimony hydride is oxidized by air or oxygen at -40° C. Black antimony is more volatile than grey antimony. Chemically active, it oxidizes in the air at atmospheric temperature. When heated to 400° C in the absence of air, black antimony transforms rapidly into ordinary antimony crystals.