How is the cubic close packed structure characterized?

The cubic close packed (CCP) structure, also known as face-centered cubic (FCC), is characterized by an ABCABC repeating pattern of layers. In this arrangement, the spheres (representing atoms) in one layer are positioned in the gaps of the layers above and below, allowing for maximum packing efficiency. This three-dimensional stacking maximizes the density of the material, which is a key feature of close-packed structures.

In each sequence, one layer is placed in a certain orientation, and the subsequent layer has its spheres placed in the octahedral and tetrahedral holes formed by the first layer. This alternation continues with the next layer repeating the positioning of the first, resulting in the ABCABC sequence.

This efficient packing arrangement is essential in many metals and contributes to their properties, including high density and structural stability. The arrangement ensures that each sphere is surrounded by a symmetrical coordination of other spheres, leading to a stable structure.

The other options do not correctly describe the cubic close packed structure. A simple ABAB pattern refers to a different packing structure known as hexagonal close packed (HCP), one layer of spheres does not capture the multi-layer nature of CCP, and a random arrangement would lead to a significant decrease in packing efficiency,