Database of Zeolite Structures
Framework Type *-SVY
Cell Parameters: hexagonal P 63 m c (# 186)  
    a = 14.4047 Å b = 14.4047 Å c = 50.3545Å  
  α = 90.000° β = 90.000° γ = 120.000°  
Volume = 9048.5Å3  
RDLS = 0.0042  
  Framework density (FDSi): 15.7 T/1000 Å3  
  Topological density: TD10 = 794  
Ring sizes (# T-atoms):  
Channel dimensionality: Topological (pore opening > 6-ring): 2-dimensional  
  Maximum diameter of a sphere:  
  that can be included 8.44 Å  
that can diffuse along a:   4.9 Å b:   4.9 Å c:   2.6 Å  
Accessible volume: 16.26   %  
Composite Building Units:
Natural Tiling t-kzd t-euo t-kah t-mel t-srs t-hpr t-mww-2 t_svy
* Disordered Type Material
The Type Material of this Framework Type is disordered. An ordered framwork structure is given here to facilitate the discription, but no bulk material with this stucture is presently known. A brief description of the disorder is given below. For more details see the original publication.
Brief description of the disorder
The framework of *-SVY can be described as a stacking of the 'MWW-type layer' shown in green on the right. There are two types of disorder present: (1) a disorder in the stacking sequence of the 'MWW-type layers' and (2) a disorder in the arrangement of the two different types of silanol groups on the surface of the 'MWW-typelayers'.
(1) The stacking of the 'MWW-type layers' is mostly ABAB but ABABCBCB-type stacking faults occur quite frequently resulting in in disorder along [001]. Faults of the type AA (MWW-type framework) are not observed.
(2) Two types of silanol groups are present on the 'MWW-type layer' surfaces, a single Si-OH (shown in purple in the green images on the right) and a cluster of 3 Si-OH (shown in red). The ratio between the two different groups is about 1:1. Although the silanol groups in the images are ordered, the arrangement is not actually known, and both groups may occur on both sides of the 'layers' in a random fashion.

Effect of the disorder on the channel system
The channel system within the 'layer' is, of course, not affected by either disorder. The stacking sequence of the 'MWW-type layers' does not affect the diffusion between the 'MWW-type layers', but the specific arrangement of the silanol groups might have an effect.
Framework images
(click on icon for larger image)

viewed normal to [001]

Projection along [100]
Projection along [110]
Projection along [001]
'layer' viewed normal to [001]
Side pocket in 'layer' surface
viewed normal to [001]
'layer' viewed normal to [001]
with silanol groups in different colors
projection of 'layer' along [001]
different silanol groups in different colors


Year code assigned 2018
Data last updated Jul 19, 2018