Intrapolytypic and interpolytypic transformation in cadmium iodide crystals

Investigations are made of intra and interpolytypic transformations on a thirty-four layered hexagonal polytype of cadmium iodide. The detailed atomic structure of the initial and transformed polytypes is determined and structural geometrical schemes embodying the transformation are suggested. Evidence and arguments are advance to show that the intrapolytypic transformations proceeds through the changes in the base units. The base units gradually change from one to the other such that the changes are always towards the dominance of the more stable units. The interpolytypic transformations, on the other hand, follows the usual pattern of disordering of the ordered stacking faults producing a 4H disordered structure.