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MINERALS AND SYNTHETIC COMPOUNDS, AmXn, WITH CLOSE
PACKED |
X
ATOMS AND A ATOMS OCCUPYING TRIGONAL PRISMATIC INTERSTICES |
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Molybdenite |
click here to see a key to this data bar
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trigonal prism |
50% |
hp |
layer |
3
edges |
A-
6c, X- 3c/hp |
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structure |
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The molybdenite layer
structure is similar to the gibbsite layer structure seen |
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before. However in molybdenite the
occupied layers are HP and alternate with |
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unoccupied layers that are packed
CCP.
The A atoms reside in 50% of the trigonal |
prismatic interstices of the occupied layer. |
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Ex. MoS2 ( molybdenum sulfide,
molybdenite ) ( Mo - A , S - X ) |
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Crystal lattice |
The lattice model shows
the occupied HP layers alternating with the unoccupied |
CCP layers. The intervening CCP layer
staggers the occupied layers relative to each |
other so that the vertical sequence of the X
atoms is AABBAA... |
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Figure 117 -
Molybdenite lattice |
click image to enlarge |
structure |
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Polyhedral framework |
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linking surfaces |
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Figure 118 - Molybdenite polyhedral |
framework model |
( 17 T, 20 S, 53 pinges ) |
3
edges |
click image to enlarge |
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The polyhedral
framework model demonstrates the AABB sequence of the X |
atoms, the staggering of the occupied AX6
groups in alternating layers, and their |
edge linkage. (the black triangles are braces) |
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Page
75 - Structure matters - Molybdenite |
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