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

ReO3

                  click here to see a key to this data bar                                  

octa

25%

fcc

chain

6 vertices

A- 6c, X- 2c/fcc

.

  structure

.
. .
     The ReO3 structure is identical to perovskite except that there is only one species .
of FCC packed X atoms.  Also 1/4 of these anions are eliminated instead of being .
substituted for.  This leaves large unoccupied cuboctahedral shaped voids in the
structure with eight AX6 groups coordinated around each.  As with perovskite 25% of
the octahedral voids are occupied and the occupied AX6 groups form vertex linked
chains parallel to the [100] axis.
  .
Ex. ReO3  ( Re - A , O - X ) .
.
Crystal lattice
     Modeled the same as perovskite except that triangles are removed from the
regions of the lattice where the cuboctahedral voids are located (in the centers of
the eight AX6 groups coordinated around them).
.
Polyhedral framework
.      

linking surfaces

ReO3.gif

 

        Figure 103 -  ReO3 polyhedral
                  framework model
              ( 64 T, 6 S, 96 pinges )

6 vertices

                         click image to enlarge
.      
     The polyhedral framework model is similar to perovskite except that squares   
are used to brace the octahedra to indicate there is a cuboctahedral void in the
center.
.
Isostructural minerals/compounds
MoF3, NbF3, TaF3, WO3 (high temperature)
.

Back to mineral table

Back to Knowhere

Home page

page 65 of lesson

Page  66 - Structure matters - ReO3

page 67 of lesson

 

home   sitemap   products   Polywood   .networks   contact us   Knowhere   3Doodlings