MINERALS AND SYNTHETIC COMPOUNDS, AmXn, IN WHICH X ATOMS ARE
          CLOSE PACKED AND A ATOMS OCCUPY OCTAHEDRAL INTERSTICES
 
.

RhF3

                  click here to see a key to this data bar                                  

octa

1/3

hcp

3-d

6 vertices

A- 6c, X- 2c/hcp
.

  structure

 .
. .
     In the RhF3 structure 1/3 of the octahedral interstices of the HCP packed X atoms .
in each successive layer are occupied with A atoms. .
  .
Ex. RhF3   (Rh - A, F - X ) .
.
Crystal lattice
   The HCP staggered sequence of the occupied AX6 coordination groups results in
a unique "spiral staircase" structure for the crystal lattice.  This coupled with the 1/3
occupancy rate of each layer causes each occupied AX6 group to overly two
unoccupied octahedral interstices.
.      
 

RhF3.gif

  
       Figure 97 -  RhF3 lattice structure

click image to enlarge

                         
   
 
.      
Polyhedral framework
.

 

 

 

linking surfaces

RhF3.gif

RhF3.gif

 

Figure 98 -   RhF3

polyhedral

framework

6 vertices

 

click image to enlarge

overhead

front

( 74 T , 100 pinges )

 

 

 

 
     The polyhedral framework model shows the spiraling of the AX6 groups and the
vertex linkage. (the black triangles are braces)
.
Isostructural minerals/compounds
PdF3, IrF3, PtO3, PtF3
.

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