Abstract: Luminescence centers were created in the CsI host crystals by annealing of Pb-doped crystals at 400℃ in air. It was found that the excitation spectra of these luminescence centers are coincided
well with the excitation absorption of a series of compounds in the Cs-Pb-I system, which indicates that they are attributed to the creation of CsPbI₃, CsPbI₆
and other aggregates in the annealing process. The emission spectra of Pb:CsI crystals were measured in the 10-30K temperature range by 360nm and 410nm excitation respectively.
The relative intensities of emission bands depend strongly on annealing time, which implies that the creation and transformation of various Pb-based aggregates in Pb:CsI
crystals tend to active around 400℃ annealing temperature.

Key words: Pb-doped CsI, Pb²⁺-based aggregates, luminescence properties