1.10.1 Wurtzite (MX) structured compounds

• Compounds with M²⁺X^2- stoichiometry

• Examples are the polymorphs of Sphalerite structured compounds such as ZnS ZnO, SiC.

• Co-ordination of both anions and cations is 4, as in Sphalerite structured compounds.

• Anions form an HCP lattice with ½ of the tetrahedral sites occupied by cations.

• The only difference to Sphalerite structure is that here anions pack in the form of ABCABC… stacking.

Figure 1.38 Wurtzite structure and polyhedral model

• As you can notice, all the tetrahedrons point in one direction i.e. along the c-axis of the unit-cell and they share the corners.

• Lattice type: Primitive, HCP

• Motif: M: 0 0 0 and ; X:   and

• The filling of structure can be seen below.

Figure 1.39 Layer by layer filling in Wurtzite