THE SIMPLE IONIC STRUCTURE : CdS
- The crystal structure of Cadmium Sulfide is one of the
derivates structure of Cubic-Close packing.
- It”s Zinc Blende (Sphalerite).
- CdS = Cd2+ + S2- Thus, Cd2+ is a cation and S2- is an anion.
- In this unit cell there are 4 anions and 4 cations, so there
are 8 atoms, with a ratio of 4:4 cations and anions
- Coordination = 4,4
- Cation coord = Tetrahedron
- Anion coord = Tetrahedron
FRAMEWORK AND INTERSTITIAL HOLES
-
-
Atom S is very large than the Cd
The anion formed the framework
The framework is a FCC
And Cd, which is the cation, will fill the interstitial hole,
The cations occupy one type of tetrahedral hole, which is
one half the tetrahedral holes ( T+ ) present in this
structure.
THE LOCATION INTERSTITIAL HOLES
-
The projection representation of CdS (Zinc Blende)
Green : S
Red : Cd
We can divide it into 4 layers, starting from the
bottom, namely zero, ¼, ½, ¾, 4/4
- There are 4 cations in the interstitial hole, located
at ¼ and ¾, each of which has 2 atoms
THE COORDINATES
 In this structure, the anion coordinates :
 ( 0,0,0 ; ½,1/2,0 ; ½,0,1/2 ; 0,1/2,1/2. )
 The tetrahedral sites (T+) coordinates :
 ( ¼,1/4,1/4 ; ¾,3/4,1/4 ; ¾,1/4,3/4 ; ¼,3/4,3/4. )