Luminescent spectroscopy of Eu2+ centers in CsBr:Eu single crystals at 10–550 K

CsBr:Eu crystals with aggregate centers have been characterized by photoluminescence measured at the temperature range 10–550 K and thermostimulated luminescence. The aggregates have been created by annealing of the CsBr with 0.42 mol% of metallic Eu in air at temperature 430–520 K. It has been shown that crystals contain nanocrystals and precipitates of the Eu2+ compounds probably of the phases of CsEuBr3, Cs4EuBr6 and EuBr2, that emit with the bands peaked at 516, 490 and 409 nm, respectively, and the isolated dipole centers of Eu2+–VCs that emit with the band peaked at 431 nm. The excitation energy transfer between isolated dipole centers Eu2+–VCs and aggregate centers and influence of the F-like centers on this process have been analyzed. It has been shown that deexcitation of Eu2+ ions takes place mainly through luminescence of aggregate centers.