Yuntao Wu, Merry Koschan, et al.
Journal of Crystal Growth
Eu2+-doped alkali or alkali earth iodide scintillators with energy resolutions ≤3% at 662 keV promise the excellent discrimination ability for radioactive isotopes required for homeland-security and nuclear-nonproliferation applications. To extend their applications to x-ray imaging, such as computed tomography scans, the intense afterglow which delays the response time of such materials is an obstacle that needs to be overcome. However, a clear understanding of the origin of the afterglow and feasible solutions is still lacking. In this work, we present a combined experimental and theoretical investigation of the physical insights of codoping-based defect engineering which can reduce the afterglow effectively in KCaI3+ single-crystal scintillators. We illustrate that Sc3+ codoping greatly suppresses the afterglow, whereas Y3+, Gd3+, or La3+ codoping enhances the afterglow. Meanwhile, a light yield of 57 000 photons/MeV and an energy resolution of 3.4% at 662 keV can be maintained with the appropriate concentration of Sc3+ codoping, which makes the material promising for medical-imaging applications. Through our thermoluminescence techniques and density-functional-theory calculations, we are able to identify the defect structures and understand the mechanism by which codoping affects the scintillation performance of KCaI3+ crystals. The proposed defect-engineering strategy is further validated by achieving afterglow suppression in Mg2+ codoped KCaI3+ single crystals.
Yuntao Wu, Merry Koschan, et al.
Journal of Crystal Growth
Yuntao Wu, Qi Li, et al.
physica status solidi RRL
Yuntao Wu, Qi Li, et al.
Advanced Optical Materials
Minjung Kim, Subhasish Mandal, et al.
Computer Physics Communications