Partial disclinations

A twin in a crystal can terminate at a partial wedge disclination. This is the analogue to a stacking fault terminating at a partial dislocation. It is illustrated for an FCC crystal. Similarly, several twins can terminate at a partial disclination. This is also illustrated for an FCC crystal. Crystals with such defects, which are called pseudopentagonal twins have been observed. Their X-ray diffraction pattern should show the elastic distortion of the disclination.