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

Abstract

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 A2BSi5O12 and ACSi2O6, 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 A2BGe5O12 and ACGe2O6. In this paper, the Rietveld refinements of three synthetic Ge-leucite analogs with stoichiometries of AAlGe2O6 (A = K, Rb, Cs) are discussed. KAlGe2O6 is I41/a tetragonal and is isostructural with KAlSi2O6. RbAlGe2O6 and CsAlGe2O6 are $I\bar{4}3d$ cubic and are isostructural with KBSi2O6.