Al2Si2O7

Al2Si2O7 is an aluminosilicate compound that belongs to the disilicate family, characterized by units in which two silicon tetrahedra share an oxygen to form Si2O7 groups. In this compound, aluminum occupies tetrahedral sites (AlO4) alongside silicon, producing a neutral three‑dimensional aluminosilicate network balanced by seven oxygen atoms per formula unit. The arrangement of SiO4 and AlO4 tetrahedra can vary with temperature and pressure, giving rise to different polymorphs in some systems.

Natural occurrence of Al2Si2O7 as a discrete mineral is uncommon; it more often appears as a synthetic phase within aluminous disilicate systems or as a component in specific metamorphic or hydrothermal assemblages. It can be produced by high‑temperature solid‑state synthesis or hydrothermal crystallization and may also form as a dehydration product of related aluminosilicate minerals under suitable conditions.

In materials science and geology, Al2Si2O7 is studied to understand the behavior of aluminum in silicate networks and the stability of disilicate units within the Al–Si–O system. Its study informs phase relations important for ceramic and glass‑ceramics research, where aluminosilicate frameworks are relevant for controlling structure and properties in heat‑resistant materials and advanced ceramics. Related disilicate compositions illustrate how different metal cations balance Si2O7 units in solid‑state continua.

See also: disilicate, aluminosilicate, silicon-oxygen tetrahedra, polymorphs, ceramic materials.