Mg-codoped Lu 3 Al 5 O 12 :Ce single crystal scintillators were prepared by a micropulling down method in a wide concentration range from 0 to 3000 ppm of Mg codopant. Their structure and chemical composition were checked by X-ray diffraction and electron probe microanalysis techniques. Absorption and luminescence spectra, photoluminescence decays, and thermoluminescence glow curves were measured together with several other scintillation characteristics, namely, the scintillation decay, light yield, afterglow, and radiation damage to reveal the effect of Mg codoping. Several material characteristics manifest a beneficial effect of Mg codopant. We propose a model explaining the mechanism of material improvement which is based on the stabilization of a part of the cerium dopant in the tetravalent charge state. The stable Ce 4+ center provides an additional fast radiative recombination pathway in the scintillation mechanism and efficiently competes with electron traps in garnet scintillators.

Photo‐ and radioluminescence characteristics of the Pr3+‐doped Lu3Al5O12 single crystal are reported and compared with those of Pr‐doped Y3Al5O12. With respect to the Y3Al5O12 host, lower emission quenching and better temperature stability round 300 K is obtained for the Pr3+ 5d–4f emission peaking round 308 nm and about a factor 2 higher radioluminescence intensity is observed around this temperature. The photoluminescence decay time is of about 17 ns, while the scintillation decay is dominated by the component of about 25 ns. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low‐dimensional halide perovskites with excellent luminescent properties have become leading candidates for optoelectronic and radiation‐detection applications. In this work, Tl cation is incorporated into 0D perovskite Cs3Cu2I5 host and an ultrabright and efficient scintillator is developed for X‐ray and γ‐ray detection. The Tl‐doped Cs3Cu2I5 crystals exhibit a high photoluminescence quantum efficiency of 79.2%. The radioluminescence emission of Cs3Cu2I5:Tl crystal under X‐ray excitation consists of a self‐trapped exciton emission at 440 nm and a Tl‐related emission at 510 nm at room temperature. With optimized Tl doping, the Cs3Cu2I5 not only demonstrates about five‐times enhanced steady‐state scintillation yield up to 150 000 photons/MeV and an improvement of X‐ray detection limit from 103.6 to 66.3 nGy s−1, but also maintains an extremely low afterglow of 0.17% at 10 ms after X‐ray cut‐off. The Cs3Cu2I5:Tl also possess a remarkable energy resolution of 3.4% at 662 keV and an ultrahigh light yield of 87 000 photons/MeV under 137Cs γ‐ray radiation.

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A novel all-inorganic CsCu2I3 single-crystalline perovskite as a nonhygroscopic and efficient X-ray and γ-ray scintillator is described herein. It is featured by a one-dimensional (1D) perovskite structure with an orthorhombic system and a space group of Cmcm. The CsCu2I3 crystal emits yellow light peaking at 570 nm originated from strongly localized 1D exciton emission. It appears self-absorption free because of the large Stokes shift of 1.54 eV. The photophysics process of the self-trapped exciton was studied using temperature dependent photoluminescene spectra and decay kinetics measurements. The CsCu2I3 crystal exhibits an extremely low afterglow level of 0.008% at 10 ms under X-ray excitation. Under 137Cs γ-ray irradiation, its light yield is 16 000 photons/MeV with an energy resolution of 7.8% at 662 keV.

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a b s t r a c tThe Mg and Ca co-doped Ce:Gd 3 Al 2 Ga 3 O 12 single crystals were prepared by micro pulling down method with a wide concentration range 0-1000 ppm of the codopants. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg and Ca co-doping. The scintillation decays were accelerated by both Mg and Ca codopants. Comparing to Ca co-doping, the Mg co-doped samples showed much faster decay and comparatively smaller light output decrease with increasing Mg dopant concentration.

Organic-inorganic hybrid halide perovskites, represented by CH 3 NH 3 PbX 3 (X ¼ Cl, Br, I), have demonstrated excellent optoelectronic and radiation detection properties. [1-3] All-inorganic CsPbX 3 perovskites (X ¼ Cl, Br, I) with better long-term stability are also considered as promising materials for optoelectronic devices and semiconductor γ-ray detectors. [4-6] Recently, there has been a surge of interest in low-dimensional perovskites due to their high photoluminescence quantum yield (PLQY). For example, the crystal structure of Cs 4 PbBr 6 that consist of spatially isolated [PbBr 6 ] 4À octahedra surrounding with Cs þ ions can be regarded as a 0D structure at molecular level, which leads to an intense quantum confinement effect. Excitons are strongly confined at each [PbBr 6 ] 4À octahedron, enabling a high exciton binding energy of 353 meV and a high PLQY of between 42% and 45%. [7,8] Quite a few low-dimensional allinorganic perovskites with remarkable luminescent properties were also reported as sensitive and efficient scintillators. Bulk crystals of 0D Cs 4 CaI 6 :Eu, Cs 4 SrI 6 :Eu, and Cs 4 EuBr 6 perovskites, isostructural to K 4 CdCl 6 trigonal system, have excellent light yields from 51 800 to 78 000 photons MeV À1 and energy resolutions from 3.3% to 4.3% at 662 keV. [9,10] However, due to a small Stokes shift of Eu 2þ ions, these materials suffer from strong self-absorption effect when scaling-up crystal size. Nanocrystals of 0D CsPbBr 3 /Cs 4 PbBr 6 perovskites show a high light yield of 64 000 photons MeV À1 and a fast decay time of <10 ns. [11] Onedimensional materials were also reported as sensitive X-ray scintillators, such as Rb 2 CuBr 3 and Rb 2 CuCl 3. [12,13] In particular, the Rb 2 CuBr 3 , that is self-absorption free and nonhygroscopic, was reported to achieve an ultrahigh scintillation yield of 90 000 photons MeV À1. [12] All-inorganic 0D perovskite Cs 3 Cu 2 I 5 was recently reported as a highly efficient blue-emitting material with a PLQY of 91.2%, and regarded as promising for application in photodetectors, light-emitting diodes, and memristors afterward. [14-17] In 2020, Cs 3 Cu 2 I 5 nanocrystals were developed for X-ray imaging with a light yield of 80 000 photons MeV À1. [18] To the best of our knowledge, the X-ray and γ-ray detection capability of bulk Cs 3 Cu 2 I 5 single crystal has not been reported. Thus, the aim of this work is to study the physical and optical properties and the scintillation performance under X-ray and γ-ray radiation of high-quality Cs 3 Cu 2 I 5 perovskite single crystal grown by the Bridgman method. The 7 mm diameter single crystal of Cs 3 Cu 2 I 5 was grown by the vertical Bridgman method. High-purity powders of CsI (99.99%, Grirem Advanced Materials) and CuI (99.999%, Sigma-Aldrich) were used as raw materials. These starting materials were mixed consistent with stoichiometric ratio and loaded into a quartz ampoule in a glovebox with <0.1 ppm moisture and oxygen. The loaded ampoule was sealed under a vacuum of 10 À6 torr after drying at 180 C for ...