Polymorf - Knowhwere- CdI2

MINERALS AND SYNTHETIC COMPOUNDS, A_mX_n, IN WHICH X ATOMS ARE

CLOSE PACKED AND A ATOMS OCCUPY OCTAHEDRAL INTERSTICES

CdI₂

click here to see a key to this data bar
octa	50%	hcp	layer	6 edges	A- 6c, X- 3c/hcp

structure

CdI₂ has a layer structure with A atoms occupying 100% of the octahedral voids of

every other layer for an overall occupancy rate of 50%. The structure is analogous to

the CdCl₂ layer structure shown previously except that the layers stack HCP not FCC.

Ex. CdI₂ (cadmium iodide) ( Cd - A , I - X )

Crystal lattice

The HCP layering arrangement of the structure is demonstrated by the lattice

model.

.

		Figure 85 - CdI₂ lattice structure
click image to enlarge


.

Polyhedral framework

Same as for CdCl₂ except that the layers are positioned in the HCP formation.

Isostructural minerals/compounds

Ag₂F, CaI₂, CdI₂, CoBr₂, CoI₂, CoTe₂, FeBr₂, FeI₂, GeI₂, HfS₂, HfSe₂, IrTe₂, MgBr₂,

MgI₂, MnBr₂, MnI₂, NiTe₂, PdI₂, PdTe₂, PtS₂, PtSe₂, PtTe₂, SiTe₂, SnS₂, SnSe₂,

a-TaS₂, TiBr₂, TiCl₂, TiI₂, TiSe₂, TiTe₂, VBr₂, VCl₂, VI₂, W₂C, ZrS₂, ZrSe₂, ZrTe₂,

Ca(OH)₂, Mn(OH)₂, Mg(OH)₂, Zn(OH)₂, Mg₄NiO(OH)₉

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Page 56 - Structure matters - CdI₂