Abstract
The effect of BiI3 doping on the optical absorption spectra and roentgeno-, photo-, and thermoluminescence of CaI2 scintillator crystals has been studied in the temperature range 90–295 K. The crystals were grown by the Bridgman-Stockbarger method. Doping of CaI2 with BiI3 from the melt gives rise to absorption bands centered at 466, 400, and 350 nm, which can be interpreted as the A, B, and C bands due to electronic transitions from the 1 S 0 state to the 3 P 1, 3 P 2, and 1 P 1 levels of a free Bi3+ ion. The absorption band at 270–290 nm is assignable to near-activator excitons. Changes in spectral composition and the reduction in luminescence intensity caused by Bi3+ doping of CaI2 are associated mainly with the reabsorption of the emission from centers characteristic of the host by activator centers. Under x-ray excitation, the spectrum of heavily doped crystals shows, in addition, a weak emission centered around 620 nm, which is probably due to an impurity phase. The light sum of CaI2:Bi3+ under x-ray excitation is small and is due to shallow traps. Upon Bi3+ substitution on the cation site of CaI2, the excess charge of the activator is probably compensated by unintentional O2− impurity and vacancy pairs near Bi3+ centers—one vacancy in a neighboring cation site and the other in a neighboring anion site.
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Original Russian Text © S.S. Novosad, I.S. Novosad, O.S. Novosad, I.A. Khvyschun, 2008, published in Neorganicheskie Materialy, 2008, Vol. 44, No. 6, pp. 760–764.
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Novosad, S.S., Novosad, I.S., Novosad, O.S. et al. Effect of BiI3 doping on the optical properties of CaI2 . Inorg Mater 44, 664–668 (2008). https://doi.org/10.1134/S0020168508060216
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DOI: https://doi.org/10.1134/S0020168508060216