The sodalite unit: truncated octrahedron. Euler’s theorem for polyhedra states that where is the number of faces, is the number of vertices, and the number of edges. There are 36 edges, 24 vertices, 6 square faces, and 8 hexagonal faces.
(a) TEM picture of zeolite-13X grains after sonication in alcohol, with a magnification of . (b) Illustration of the alumino-silicate framework of the X-type zeolite by joining the units of cubo octahedra linked with each other. The pointer shows the sodalite units.
(a) TEM picture of zeolite-Y grains after sonication in alcohol, with a magnification of . (b) Illustration of the framework of zeolite-Y type with the assembly of the sodalite units showing the supercage (Ref. 16).
Pore size distribution obtained from BET in (a) zeolite-Y and (b) zeolite-H (—●—for cage during adsorption and—엯—for cage during desorption) samples. (c) BET curve of adsorption-desorption isotherm for zeolite H showing hysteresis.
Positronium lifetime spectra for zeolite 13X (●) and zeolite H (엯) depicting the noticeable change in slope for the long-lifetime component (indicating larger cavity) of zeolite H (-axis channel ).
The wide-angle x-ray-diffraction studies showing the crystallinity factor and particle size measured from the Scherrer method.
The long-lived components of positronium annihilation parameters as determined from the positron lifetime spectroscopy and the evaluated void sizes from Eqs. (6) and (7) for the respective cases.
The pore structures as determined from BET adsorption-desorption isotherms for zeolite-Y and zeolite-H forms.
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