The crystallography of grain boundaries in crystals of lower symmetry was considered. It was suggested that only twin boundaries were singular in nature. There were difficulties in applying the CSL model to the analysis of interfaces in non-cubic materials. It was shown that the reciprocal volume density of coincident sites was not the primary parameter which governed the grain boundary structure and properties.

On the Applicability of the CSL Model to Grain Boundaries in Non-Cubic Materials. V.Y.Gertsman, J.A.Szpunar: Materials Science Forum, 1999, 294-296, 181-6