# Superstructure

### From Online Dictionary of Crystallography

Surstructure (*Fr*). Superstruttura (*It*). 超構造 (*Ja*).

A **superstructure** is a crystal structure S’ obtained from another crystal structure (called a **basic structure**) S under the following conditions:

- the space group G’ of S is a subgroup of the space group G of S;
- the translation subgroup T(G’) of S’ is a subgroup of translation subgroup T(G) of S, i.e. the unit cell of S’ is a supercell of the unit cell of S and the lattice of S’ is sublattice of the lattice of S;
- the point group of P’ of S’ may either coincide with the point group P of S or be a subgroup of it;
- at least one of the Wyckoff positions of S is split into two or more independent Wyckoff positions of S’ and the corresponding crystallographic orbits are occupied by chemically different atoms.

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## See also

- Derivative structure
- Substructure
- Martin J. Buerger:
*Journal of Chemical Physics***15**(1947) 1-16.