Which of the following is NOT a type of crystal defect?

In the context of crystallography and materials science, crystal defects are variations from perfect crystal structures that can significantly impact the properties of materials. The types of defects include point defects, line defects, and surface defects.

Point defects are localized disruptions within the crystal lattice, such as vacancies (missing atoms), interstitials (extra atoms positioned in the lattice), or substitutional defects (where an atom is replaced by a different atom).

Line defects, often referred to as dislocations, extend in one dimension and impact how materials deform under stress. They play a crucial role in the mechanical properties of metals and other materials.

Surface defects, also known as macroscopic defects, occur at the boundaries of grains or at the surfaces of crystals and can influence a material's reactivity and mechanical strength.

The term "atomic lattice," however, refers to the regular arrangement of atoms in a crystalline structure, rather than a type of defect. It describes the underlying framework of the crystal and does not represent any imperfection or variation within that structure. Therefore, it does not fit into the classification of defects, making it the correct answer for this question.