# Aluminium sesquioxide, Al2O3

Al2O3, commonly known as alumina or aluminum oxide, is a ceramic material that has a wide range of applications due to its excellent mechanical and optical properties. This compound crystallizes in various phases, the most stable and common of which is the corundum structure. Alumina is transparent in the ultraviolet to the infrared range, making it a versatile material for a variety of optical applications such as protective windows and lenses. It has a high refractive index and is also known for its strong dielectric properties. One of the key attributes of Al2O3 is its remarkable thermal stability and resistance to chemical attack, which makes it suitable for harsh environment applications. Furthermore, the material has been investigated for its nonlinear optical characteristics, although it is generally less efficient in this regard compared to other nonlinear optical materials. Alumina can also serve as a substrate material for thin-film optical coatings. In summary, Al2O3 is a robust and multifunctional material that is extensively studied for its enduring relevance in both traditional and advanced optical systems.

## Other names

- Alumina
- Aluminium oxide
- Aloxite
- Aluminium oxide (α)
- Aluminium(III) oxide
- Dialuminium trioxide

## Mineral

- Corundum

## Gemstones

- Sapphire
- Ruby

## External links

- Aluminium oxide - Wikipedia
- Aluminium oxide (α) - WebElements
- Corundum - Wikipedia
- Sapphire - Wikipedia
- Ruby - Wikipedia