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MINERALS AND SYNTHETIC COMPOUNDS, AmXn, IN WHICH X
ATOMS ARE |
CLOSE PACKED AND A ATOMS OCCUPY OCTAHEDRAL INTERSTICES |
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RhF3 |
click here to see a key to this data bar
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octa |
1/3 |
hcp |
3-d |
6
vertices |
A-
6c, X- 2c/hcp |
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structure |
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In the RhF3
structure 1/3 of the octahedral interstices of the HCP packed X atoms |
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in each successive
layer are occupied with A atoms. |
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Ex. RhF3 (Rh - A, F - X ) |
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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. |
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Figure 97 - RhF3 lattice structure |
click image to enlarge |
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Polyhedral framework |
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linking surfaces |
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Figure 98 - RhF3 |
polyhedral |
framework |
6
vertices |
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click image to enlarge |
overhead |
front |
( 74
T , 100 pinges ) |
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The polyhedral
framework model shows the spiraling of the AX6 groups and the |
vertex linkage. (the black triangles are braces) |
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Isostructural minerals/compounds |
PdF3,
IrF3,
PtO3, PtF3 |
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Page
63 - Structure matters - RhF3 |
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