X-ray and electron diffraction studies of cadmium iodide crystals in relation to the hexagonal-rhombohedral polytypic transformation

X-ray and electron diffraction studies of as-grown CdI2 crystals from solution show that in a number of them hexagonal and rhombohedral polytypes coexist on the same basal face. Analyses of selected area electron diffraction patterns taken from different regions on the edges of various crystals reveal that the transformation of a hexagonal polytype into a rhombohedral along the basal face takes place as a result of formation of twinning in the orientation (11.n) [11.6/n] in the intermediate regions between them. (author)