Question

Question 61 [6 marks] (a) In the crystal structure of sphalerite (ZnS), the sulfur anions (S2) adopt a face-centred cubic arrangement. Using the cubic framework shown below, draw the anion locations in a face-centred cubic unit cell. (Represent each ion as a small solid circle). For the face-centred cubic unit cell you have drawn in (a), how many sulfur anions (b) make a contribution to the unit cell? What is the sulfur anion content of the face-centred cubic unit cell you have drawn in (a) (c) (i.e. how many sulfur anions are contained within the unit cell)? (d) In sphalerite (ZnS) the Zn2+ cations are accommodated in the tetrahed ral holes between the S2- anions. Circle the correct percentage of the total number of tetrahedral holes that are filled with a zinc cation. 100% 75% 50% 25%

Answer 1

ttoms cet corner. contributes = 1 Atoms at face centre cont ② Total number of se 2 x 8 + 1 X6 1 +3 = © 6 Sulphur atoms in unit cell = 4 @ 202+ occupy hath of telahedral voids - So answer is (50 %)