The ordering of defects controlled by the symmetry of the CdI2 crystal lattice: Justification and experimental confirmation

The low symmetry of the crystals of the layered structure causes a clear spatial arrangement of associates of point defects. The generation of complexes of donor-acceptor-donor trimmers is the result of such a process. Crystals like CdI2 serve the ideal object for the justification of such associates creation. Peculiarities of the AX2 (CdI2) crystals causes the ordering of the local minimum of thermodynamic potentials at the sites occupied by cadmium cations. Model of donor-acceptor defects caused by mentioned above nonstoichiometric Cd inclusions is considered. The influence of the concentration of nonstoichiometric Cd inclusions on the electro-optical and photoelectric properties of CdI2 crystals is studied experimentally and theoretically using virtual crystal model and peculiarities of energy band due to different chemical bond in different directions.