What Is The Structure Of Aluminium Selenide?

Aluminium selenide (Al2Se3) is a chemical compound that belongs to the family of binary compounds consisting of aluminium and selenium. It has a crystal structure characterized by a hexagonal unit cell, which contains two formula units of Al2Se3.

The aluminium atoms occupy two-thirds of the octahedral sites in the crystal structure, while the selenium atoms occupy one-third of the tetrahedral sites. The overall structure of Al2Se3 consists of layers of covalently bonded Se atoms stacked in an ABAB pattern, with Al atoms occupying the octahedral interstices between these layers.

The bonding in Al2Se3 is primarily covalent, with the aluminium atoms donating electron density to the selenium atoms to form Al-Se bonds. These bonds are polarized due to the electronegativity difference between aluminium and selenium, with the Al atoms carrying a partial positive charge and the Se atoms carrying a partial negative charge.

Overall, the crystal structure of aluminium selenide can be thought of as a series of covalently bonded layers held together by weak van der Waals forces between the layers. This arrangement gives rise to its characteristic physical properties, such as its high melting point, hardness, and electrical conductivity.