Polymorf - Knowhwere- Molybdenite

MINERALS AND SYNTHETIC COMPOUNDS, A_mX_n, WITH CLOSE PACKED

X ATOMS AND A ATOMS OCCUPYING TRIGONAL PRISMATIC INTERSTICES

Molybdenite

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trigonal prism	50%	hp	layer	3 edges	A- 6c, X- 3c/hp

structure

The molybdenite layer structure is similar to the gibbsite layer structure seen

before. However in molybdenite the occupied layers are HP and alternate with

unoccupied layers that are packed CCP. The A atoms reside in 50% of the trigonal

prismatic interstices of the occupied layer.

Ex. MoS₂ ( molybdenum sulfide, molybdenite ) ( Mo - A , S - X )

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...

Polyhedral framework

.
linking surfaces
		Figure 118 - Molybdenite polyhedral
		framework model
		( 17 T, 20 S, 53 pinges )
3 edges		click image to enlarge
.

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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