Change in optical properties of CuI crystals upon annealing in vacuum

Copper iodide crystals with different compositions of crystalline defects have been prepared using the developed technique for their synthesis and annealing in vacuum with subsequent quenching. The spectra of absorption, excitation, and photoluminescence of the CuI crystals, as well as their electrical resistance, have been analyzed. It has been found that the optical properties of the crystals change as a result of the increase in the number of point defects and inclusions of the second phase in the samples after high-temperature annealings (as compared to low-temperature annealings). This effect is caused by the deviation of the composition of the material from stoichiometry during annealing in vacuum.