Germanate Zeolites: Contrasting the Behavior of Germanate and Silicate Structures Built from Cubic T8O20 Units (T=Ge or Si)

Cubic T8O20 clusters constructed from regular TO4 tetrahedra are flexible and can have large T-O-T angles suitable for T=Si (left). With lower T-O-T angles (right) they are suitable for T=Ge. The linkage of such units is compared and contrasted in silicate and in newly discovered germanate zeolitelike materials.