Structure of hexagonal zinc sulfide

Symmetry in Chemistry 10.2.2 Structure of hexagonal zinc sulfide 

In the crystal structure of hexagonal zinc sulfide (wurtzite), the S atoms are arranged in hep, in which half of the tetrahedral interstices are filled with Zn atoms, and the space group is C v — P6imc. The positions of atoms in the hexagonal unit cell are 

The Zn atoms are each tetrahedrally coordinated by four S atoms, and likewise the S atoms are each connected to four Zn atoms, as shown in Fig. 10.2.2. The bonding has both covalent and ionic character. 

Note that an equivalent stmeture is obtained when the positions of the Zn and S atoms are interchanged, but in this case the polar direction of the crystal is reversed. This arises because Pfymc is a polar space group, and historically the polar sense of a single crystal of ZnS has been used to demonstrate the breakdown of Friedel s law under conditions of anomalous dispersion. 

Many binary compounds adopt the structure type of hexagonal zinc sulfide. Table 10.2.2 lists some of these compounds and their unit-cell parameters. 

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