# Substructure

### From Online Dictionary of Crystallography

Sous-structure (*Fr*). Sottostruttura (*It*). 部分構造 (*Ja*).

A crystal structure is composed by a finite number N of crystallographic orbits. When N > 1, a subset N’ (1 ≤ N’ < N) of the crystallographic orbits of S defines a **substructure**.

In chemistry and material science literature a substructure is often but incorrectly called a sublattice. A lattice is a mathematical description of the periodicity of a crystal structure and does not possess atomic nature. Furthermore, the translation lattice built on the subset of atoms defining a substructure can either coincide with the lattice of the original structure or be a superlattice of it, but never a sublattice.