Impact of impurities Cs+, Mg2+, Fe2+, and Sn2+ on scintillation performance of SrI2(Eu)

Abstract

In this study, the impact of impurities on the scintillation performance of SrI2(Eu) was characterized along with their segregation behavior. Single crystals of SrI2 codoped with 4% Eu and 0.2% X = {Cs, Mg, Fe, Sn} were grown by the vertical Bridgman-Stockbarger method from the melt. Pulse-height gamma ray spectroscopy measurements demonstrated that samples codoped with Cs, Mg, and Fe were slightly degraded in light yield and energy resolution. No significant impact on the decay time and emission peak centroid, 1.5 μs and 428 nm, respectively, were observed. However, the Sn-codoped sample possessed only 55% of the light yield and only half the resolution of SrI2(Eu). In addition to its Eu2+ 5d-4f emission at 428 nm, a broader emission above 550 nm was observed in this sample, accompanied by a shorter decay time of 1.1 μs. Moreover, Sn did not segregate as well as Cs, Mg, and Fe, and thus cannot be removed as easily during growth or zone refining purification. Finally, the results of this study will aid in developing a better understanding of how codoping influences light output.