Hexagonal prism atom distribution

Fig. 3 Stereoscopic view of hexagonal prism atom distribution in nickel faujasite. Reproduced with permission from reference 17. (Copyright 1968 American Chemical Society)...

The linking pattern of two zeolites is shown in Fig. 16.24. They have the /I-cage as one of their building blocks, that is, a truncated octahedron, a polyhedron with 24 vertices and 14 faces. In the synthetic zeolite A (Linde A) the /3-cages form a cubic primitive lattice, and are joined by cubes. j3-Cages distributed in the same manner as the atoms in diamond and linked by hexagonal prisms make up the structure of faujasite (zeolite X). 

The distribution of cations in a hydrated zeolite is mainly controlled by their sizes and can be described by a statistical model. In the dehydrated state, most of the cations are located on the intraframework sites their occupancies are governed by mutual repulsions and cation—framework interactions [1]. By which, the environments of the framework silicon atoms and their corresponding ssi NMR spectra are affected [2,3]. The chemical shift and lineshape of Si NMR have been found to depend on the nature and the distribution of cations in the small sodalite and double hexagonal prism (D6R) cavities of the dehydrated Y zeolites [3] The irreversible migration of La3 ions from the supercages to the small sodalite and/or D6R cavities by... 

The cations, M, are distributed over cation sites located in the supercages, the sodalite cages and the hexagonal prisms of the faujasite structure (ref.9). The SiCl4 molecule has access to the supercages only. When the number of supercage cations is compared to the number of A1 atoms that were actually... 

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