Solid-solid phase transitions between 2 polytypes were investigated by using an ab initio density functional scheme, beginning from a model that was based upon dislocations. As an example, the transformation from 6H-type to 3C-type material was studied in detail. The energy barrier to twinning a tetrahedron was calculated to be about 0.77eV per bond. This suggested that a dislocation mechanism might be responsible for the temperature and deformation-induced transitions which were observed experimentally.

Polytypic Transformations in SiC. P.Käckell, J.Furthmüller, F.Bechstedt: Physical Review B, 1999, 60[19], 13261-4