The close-packed planes of a <cubic close-packed structure> are \b[$\{111\}$], with \b[$ABCABC\ldots$] stacking. Each layer is a triangular array; the third layer occupies the remaining set of hollows rather than returning above the first.

Solution

Past exam of the materials science course of the University of Cambridge / 2017 / Paper 1 / 4 / a / i / Solution

 Solution (source code)