Crystal structures and X-ray powder diffraction data for AAlGe₂O₆ synthetic leucite analogs (A = K, Rb, Cs)

Leucites are tetrahedrally coordinated silicate framework structures with some of the silicon framework cations that are partially replaced by divalent or trivalent cations. These structures have general formulae A 2 B Si 5 O 12 and AC Si 2 O 6 , where A is a monovalent alkali metal cation, B is a divalent cation, and C is a trivalent cation. There are also leucite analogs with analogous tetrahedrally coordinated germanate framework structures. These have general formulae A 2 B Ge 5 O 12 and AC Ge 2 O 6 . In this paper, the Rietveld refinements of three synthetic Ge-leucite analogs with stoichiometries of A AlGe 2 O 6 ( A = K, Rb, Cs) are discussed. KAlGe 2 O 6 is I 4 1 /a tetragonal and is isostructural with KAlSi 2 O 6 . RbAlGe 2 O 6 and CsAlGe 2 O 6 are I4̄3d cubic and are isostructural with KBSi 2 O 6 .