For the cubic structures of analcime Na1.71(Al1.8,Si4.2)O12·2H2O, pollucite CsAlSi2O6 and tetragonal (but pseudo-cubic) kirchhoffite CsBSi2O6 and leucite KAlSi2O6 the common stencil (pattern) of cation arrangement at the key positions of symmetry space groups related with configurations in spinel, diamond, garnet, and other structure types is determined. For the mutual ordering of the positions of large cations with anions the presence of two sublattices related by a pseudo-sixfold axis in the diffraction (reciprocal) space is shown.
- crystallographic analysis
- pseudosymmetry of cation-anion ordering
- stable stencil (pattern) of cation sublattices
- ELASTIC BEHAVIOR