DOI

The crystal structures of compounds with the general formula Cs{[6] Al2[[4] TP6O20]} (where T = Al, B) display order−disorder (OD) character and can be described using the same OD groupoid family. Their structures are built up by two kinds of nonpolar layers, with the layer symmetries Pc(n)2 (L2n+1‐type) and Pc(a)m (L2n‐type) (category IV). Layers of both types (L2n and L2n+1) alternate along the b direction and have common translation vectors a and c (a ~ 10.0 Å, c ~ 12.0 Å). All ordered polytypes as well as disordered structures can be obtained using the following partial symmetry operators that may be active in the L2n type layer: the 21 screw axis parallel to c [– – 21] or inversion centers and the 21 screw axis parallel to a [21 – –]. Different sequences of operators active in the L2n type layer ([– – 21] screw axes or inversion centers and [21 – –] screw axes) define the formation of multilayered structures with the increased b parameter, which are considered as non‐ MDO polytypes. The microporous heteropolyhedral MT‐frameworks are suitable for the migration of small cations such as Li+, Na+ Ag+. Compounds with the general formula Rb{[6]M3+[[4]T3+P6O20]} (M = Al, Ga; T = Al, Ga) are based on heteropolyhedral MT‐frameworks with the same stoichiometry as in Cs{[6] Al2[[4] TP6O20]} (where T = Al, B). It was found that all the frameworks have common natural tilings, which indicate the close relationships of the two families of compounds. The conclu-sions are supported by the DFT calculation data.

Original languageEnglish
Article number708
Number of pages14
JournalMinerals
Volume11
Issue number7
DOIs
StatePublished - 30 Jun 2021

    Scopus subject areas

  • Geology
  • Geotechnical Engineering and Engineering Geology

    Research areas

  • Aluminophosphates, Borophosphates, DFT, Heteropolyhedral framework, Modularity, OD structures, Polymorphism, Polytypism, Topology, borophosphates, ION CONDUCTORS, polytypism, polymorphism, DY3+, modularity, FAMILIES, heteropolyhedral framework, BOROPHOSPHATE GLASSES, METALLOBOROPHOSPHATES, aluminophosphates, topology, BEHAVIOR, CRYSTAL-CHEMISTRY, FRAMEWORKS, LAYERS, KIND

ID: 88647642