Database of Disordered Zeolite Structures
 
Intergrowth Family IM-18
Periodic Building Unit
 
  Periodic Building Unit (PerBU): Layer of isolated zig-zag chains  
 
  Layer symmetry P m m (2)  
 
  Comment To facilitate understanding of the connectivity patterns shown below, O atoms that connect to a single row of d4r units have been highlighted in the layer of isolated zig-zag chains shown to the right.
 
 
Connector
  Unit d4r  
 
  References

    Cichocka, M.O., Lorgouilloux, Y., Smeets, S., Su, J., Wan, W., Caullet, P., Bats, N., McCusker, L.B., Paillaud, J.L. and Zou, X.D.
   "Multidimensional disorder in zeolite IM-18 revealed by combining transmission electron microscopy and X-ray powder diffraction analyses"
   Crystal Growth Des., 18, 2441-2451 (2018)

Connectivity pattern
Examples


 
Symmetry
Operation*
Translation* Comment Image
0
  d4r units in position 1
1/2a
  d4r units in position 2
1/4a
  
-1/4a
  
 

* relative to the previous layer of connectors

Positions of d4r unit connectors in a row
There are two possible positions for a row of d4r units above two neighboring zig-zag chains in the layer. The position of the first d4r unit (along a) determines the positions of all the other d4r units in that row.

Disorder along b: arrangements of the rows of d4r unit connectors
The arrangement of the rows of d4r units is not necessarily periodic along b. Each row can be the same as the neighboring one or shifted by 1/2a.
Effect on channel system
  The disorder can block one or both of the straight 10-ring channels (e.g. those present in polymorphs A and B) when both d4r positions are present in a single layer of d4r units (see polymorph C).
Simplest ordered end members
Connectors are shown in light blue.
Adjacent PerBUs generated by the same connectivity pattern (with or without connectors in between) are shown with different shades of the same color for clarity.

 
  Polymorph EOS
 
Cell Parameters: monoclinic P 1 2/m 1: (# 10)
  a = 9.0869 Å b = 7.5548 Å c = 10.4762 Å  
  α = 90.000° β = 108.333° γ = 90.000°  
  Volume = 682.7 Å3
Framework Density (FDSi): 17.6
Ring sizes (# T-atoms): 10  8  6  5  4    
Channel dimensionality: Topological (pore opening > 6-ring): 3-dimensional  
  Maximum diameter of a sphere:  
    that can be included 4.96 Å  
    that can diffuse along a:  3.72 Å b:  4.43 Å c:  3.01 Å  
    [0 1 0] :  4.43 Å
    addional volume data  
Composite Building Units:
d4r
mtw
Note: This polymorph corresponds to the ordered framework EOS
 
 
  Polymorph IM-18_B
 
Cell Parameters: orthorhombic P m m a: (# 51)
  a = 17.1828 Å b = 7.5138 Å c = 10.4477 Å  
  α = 90.0000° β = 90.0000° γ = 90.0000°  
  Volume = 1348.9 Å3
Framework Density (FDSi): 17.8
Ring sizes (# T-atoms): 10  8  6  5  4    
Channel dimensionality: Topological (pore opening > 6-ring): 3-dimensional  
  Maximum diameter of a sphere:  
    that can be included 5.1 Å  
    that can diffuse along a:  3.88 Å b:  4.54 Å c:  2.88 Å  
    [0 1 0] :  4.54 Å
    addional volume data  
Composite Building Units:
d4r
mtw
In this space group and setting, the ordered connecting rows are along [001] and the layers are stacked along [100]

Note: This polymorph has NOT been observed as a pure ordered material
 
 
  Polymorph ITW
 
Cell Parameters: monoclinic C 1 2/m 1: (# 12)
  a = 10.4496 Å b = 15.0277 Å c = 8.9537 Å  
  α = 90.000° β = 105.640° γ = 90.000°  
  Volume = 1354.0 Å3
Framework Density (FDSi): 17.7
Ring sizes (# T-atoms): 8  6  5  4    
Channel dimensionality: Topological (pore opening > 6-ring): 2-dimensional  
  Maximum diameter of a sphere:  
    that can be included 4.73 Å  
    that can diffuse along a:  2.78 Å b:  1.54 Å c:  3.95 Å  
    addional volume data  
Composite Building Units:
d4r
In this space group and setting, the ordered connecting rows are along [001] and the layers are stacked along [100]

Note: This polymorph corresponds to the ordered framework ITW