AlSiO4

AlSiO4 is a term used in aluminosilicate chemistry to describe a framework motif rather than a discrete neutral molecule. It refers to arrangements in which silicon and aluminum occupy tetrahedral coordination with oxygen, forming a three-dimensional network in which SiO4 and AlO4 tetrahedra share corners. In natural and synthetic aluminosilicates, aluminum substitutes for silicon in the framework, introducing a negative charge that must be balanced by extra-framework cations such as sodium, potassium, or calcium.

Because of the charge-balancing requirement, a standalone neutral AlSiO4 molecule does not exist under ordinary conditions. Instead, the material is described by the combination of SiO4 and AlO4 units, the overall framework composition, and the compensating cations. The aluminum-to-silicon ratio (often denoted by x in Si1−xAlxO2x forms) reflects the degree of substitution and the resulting framework charge, which influences properties such as acidity, ion-exchange capacity, and thermal stability.

Occurrence and applications: Aluminosilicate frameworks are widespread in nature and technology. Natural minerals such as feldspars, micas, clays, and zeolites feature SiO4 and AlO4 tetrahedra linked into networks. Synthetic aluminosilicates are crucial in ceramics, catalysts, and industrial ion-exchange materials. Zeolites, in particular, rely on well-defined Al–Si frameworks to provide catalytic activity and selective adsorption, properties governed by the aluminum content and the balance of compensating cations.

Nomenclature: The shorthand AlSiO4 emphasizes the presence of both aluminum and silicon in a silicate framework, but precise descriptions rely on the full framework composition, including the distribution of AlO4 and SiO4 tetrahedra and the counterbalancing cations.