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 (L_2n+1-type) and Pc(a)m (L_2n-type) (category IV). Layers of both types (L_2n and L_2n+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 L_2n 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 L_2n 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 conclusions are supported by the DFT calculation data.

A scheme was proposed for the first time to produce analogs of the natural minerals sampleite NaCaCu₅(PO₄)₄Cl⋅5H₂O and lavendulan NaCaCu₅(AsO₄)₄Cl⋅5H₂O from intermediate products produced by AO Apatit and AO Kol’skaya GMK. The obtained compounds are promising functional materials: they exhibit antiferromagnetic properties in a magnetic field and can be used, e.g., in designing memory cells operating at low temperatures, and also as ionic conductors.