Crystallographic description of coincidence‐site lattice interfaces in homogeneous crystals

Coincidence-site lattice interfaces (CSLI) are frequently observed in crystals where a rigid framework remains invariant on both sides of the interface. They also seem to minimize the interface energy, for example, in metals where, empirically, the greater the density of the coincidence-site lattice the more stable the grain boundary becomes. Group-theory considerations allow the determination of all the possible interface operations which leave a given sublattice invariant. A classification of these CSLI with respect to the number of equivalent sublattices they leave invariant is a guide for the prediction of the most stable type of interfaces with respect to the sublattice considered. Examples from different types of crystals illustrate the method, which also applies for translation boundaries, twins and grain boundaries.