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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 language | English |
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Article number | 708 |
Number of pages | 14 |
Journal | Minerals |
Volume | 11 |
Issue number | 7 |
DOIs | |
State | Published - 30 Jun 2021 |
ID: 88647642