Compositional regulation of multi-component GYGAG:Ce scintillation ceramics:Self-sintering-aid effect and afterglow suppression

(Gd,Y,Ce)_(3)(Y_(x)Ga_(1−x))_(2)GaAl_(2)O_(12)(GYGAG:Ce)scintillation ceramics with different Y excess,where x=0.005−0.08,were fabricated by the solid-state reaction method.The effects of stoichiometry on the phase composition,optical quality,and microstructure of GYGAG:Ce ceramics were analyzed.GYGAG:Ce ceramics have a pure garnet phase and obtain good in-line transmittance when x<0.04,while more Y excess leads to the creation of the secondary phase.The change of x value influences the sintering behavior of the GYGAG:Ce ceramics:The excess of Y works as the self-sintering aid and significantly reduces the sintering temperature of ceramics.When x=0.01–0.04,the X-ray excited luminescence(XEL)spectra and light yields of GYGAG:Ce ceramics are similar.The fast scintillation decay time and afterglow intensity of GYGAG:Ce ceramics show a slight decrease with increasing x value.Finally,additional 50–500 ppm MgO and 100–500 ppm CaO were introduced to the GYGAG:Ce ceramic with x=0.04,and both were found to significantly increase the fast scintillation component and reduce the afterglow intensity by two orders of magnitude to 0.01%after X-ray cut-off.

Exciton-harvesting enabled efficient charged particle detection in zero-dimensional halides

Materials for radiation detection are critically important and urgently demanded in diverse fields,starting from fundamental scientific research to medical diagnostics,homeland security,and environmental monitoring.Lowdimensional halides(LDHs)exhibiting efficient self-trapped exciton(STE)emission with high photoluminescence quantum yield(PLQY)have recently shown a great potential as scintillators.However,an overlooked issue of excitonexciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications.Here,we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional(0D)Cs_(3)Cu_(2)I_(5):Tl halide single crystals by forming strongly localized Tl-bound excitons.Because of the suppression of nonradiative exciton-exciton interaction,an excellentα/βpulse-shape-discrimination(PSD)figure-of-merit(FoM)factor of 2.64,a superior rejection ratio of 10^(−9),and a high scintillation yield of 26000 photons MeV−1 under 5.49 MeVα-ray are achieved in Cs_(3)Cu_(2)I_(5):Tl single crystals,outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications.Furthermore,a radiation detector prototype based on Cs_(3)Cu_(2)I_(5):Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications.We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.