Aluminium Oxide

The chemical compound aluminium oxide, often abbreviated as Al2O3, is an inorganic substance with the formula AlO. It is a white, odorless, powder that is water insoluble. It is a basic anhydride that reacts with acids and weak bases. It is a strong reducing agent and acts as the base in a number of chromatographic techniques.

It is a major raw material in the production of advanced engineering ceramics. Its hardness, bio-inertness and resistance to attacks by acid and alkali substances makes it an excellent choice for producing everything from clay bowls to advanced electronics. It is also used for high-temperature electrical and voltage insulators, seal rings in gas laser tubes and other laboratory equipment. The hardness and low-reactivity of aluminium oxide also make it a valuable material in the production of synthetic sapphires and rubies.

The lack of acute toxicity, apart from skin irritation, and the slight chronic toxicity of aluminium oxide makes it an essential and cost-effective material for use in the medical industry where it is employed to treat diaper rash. It is also a common ingredient in many antacid products.

The crystalline form of aluminium oxide, called a-alumina or corundum, crystallizes with a hexagonal close-packed structure where the oxygen atoms are octahedrally coordinated by six aluminum atoms with trivalent aluminum cations filling two thirds of the octahedral interstices. This octahedral structure allows the formation of a number of different morphologies. These can be controlled by the method of synthesis.