Zinc blende 6: the tetrahedral hole between close-packed layers

The image from the previous page is reproduced with only the critical atoms showing; the zinc ion is virtually in contact with its neighbours. You will need to rotate the tetrahedron so that a triangular face of sulfide ions is oriented horizontally, with the zinc ion between it and the remaining sulfide ion above. This shows how the central zinc ion nestles between the sulfide ions from close-packed layers above and below.

Since the zinc ions are quite a lot smaller than the sulfide ions, the latter are only pushed apart a small amount by the zinc. The ions in the holes should be larger than the holes in the surrounding close-packed lattice. If not, then the ions of the close-packed lattice would be in contact, and since like charges repel this would make the structure unstable.

The following pages take a more advanced approach.

Go to page 7 to consider the equivalence of the zinc and sulfide ions in the lattice.

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