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All‐inorganic halide perovskites appear as a promising class of scintillators for radiation detection applications due to their excellent optoelectronic properties. Herein, a self‐activated perovskite CsEuBr3 single crystal is developed as an efficient X‐ and γ‐ray scintillator. Single crystals of CsEuBr3 are grown by the Bridgman method. The phase structure, stability, photophysics properties, and scintillation performance of CsEuBr3 single crystals are studied. Under X‐ray irradiation, its emission peaks at 445 and 510 nm, associated with Eu2+ 5d–4f and defect‐related emission, respectively, are studied. Under 137Cs gamma irradiation, it has a decent light yield of 22 000 ± 2000 photons MeV−1 and an energy resolution of 6.2 ± 0.4% at 662 keV with a scintillation decay of 510 ns. [ABSTRACT FROM AUTHOR]

Low‐dimensional organic–inorganic hybrids have emerged as promising X‐ray scintillators due to efficient radioluminescence properties. Herein, stable and efficient X‐ray scintillator based on 0D (C40H38P2)MnBr4 hybrid single crystals grown by a facile solution‐processing method is reported. Its crystal structure is determined to be triclinic with P1¯ space group. It has good stability against moisture and irradiation. (C40H38P2)MnBr4 with tetrahedrally coordinated Mn2+ exhibits green emission peaking at 518 nm originating from d–d 4T1→6A1 transition of Mn2+ ion with a high photoluminescence quantum yield (PLQY) of 74.2%. Under X‐ray excitation, it shows high scintillation yield of 32 000 photons MeV−1, a decent detection limit of 288 nGyair s−1, and a low afterglow comparable to that of Bi4Ge3O12 (BGO). [ABSTRACT FROM AUTHOR]

0D halide perovskite Cs3Cu2I5‐based nanocrystals and bulk crystals are proven to be sensitive and efficient scintillators for X‐ray and γ‐ray detection. Herein, undoped and Tl‐doped Cs3Cu2I5 microcrystalline films are synthesized by a thermal evaporation method. Both films crystallize into a Pnma space group of orthorhombic crystal lattice with preferred (004) growth orientation. The undoped Cs3Cu2I5 thin film shows a sole emission peaking at 440 nm associated with the self‐trapped exciton emission. Doping of Tl+ ions introduces another emission that peaks at 520 nm. The scintillation efficiency of both undoped and Tl‐doped Cs3Cu2I5 thin films is about one‐third of that of CsI:Tl thin film with the same size and thickness. Within the first 5 s after X‐ray cutoff, afterglow signals of both the undoped and Tl‐doped Cs3Cu2I5 thin films are over one order of magnitude lower than that of CsI:Tl thin film. [ABSTRACT FROM AUTHOR]

Low‐dimensional halide perovskites with highly efficient luminescent properties have attracted huge attention in optoelectronic and radiation detection applications in recent years. Herein, a highly efficient 0D Cs3Cu2I5 perovskite crystal is presented for X‐ray and γ‐ray detection that can be easily grown from the melt by the Bridgman method. The crystal structure of Cs3Cu2I5 belongs to an orthorhombic system with a space group of Pnma. The Cs3Cu2I5 crystal is nonhygroscopic and self‐absorption free due to a large Stokes shift of 120 nm originated from its self‐trapped exciton emission. Its scintillation emission centers at 440 nm with a principal decay time of 967 ns. The Cs3Cu2I5 crystal not only demonstrates a high scintillation yield of about 32 000 photons MeV−1 and an extremely low afterglow of 0.03% at 10 ms under X‐ray radiation, but also possesses a high light yield of 29 000 photons MeV−1 with an excellent energy resolution of 3.4% at 662 keV under γ‐ray radiation. [ABSTRACT FROM AUTHOR]

This research deals with a novel approach for the self‐flux growth of Tb3Al5O12:Ce single crystal using the micro‐pulling‐down method. The self‐flux method enables the fabrication of the crystals with excellent photoconversion and scintillation properties. Tb3Al5O12:Ce (TbAG:Ce) efficiently converts the blue light‐emitting diode (LED) radiation into bright white light. The gradual change of crystal thicknesses (0.2–1 mm) allows for tuning white light temperature from cold to neutral white. The scintillation response is comparable with that of a high‐quality single crystalline film counterpart with a light yield value of around 4500 photons MeV−1 under α particle excitation from 239 Pu radioisotope. This is the highest value obtained for the TbAG:Ce crystal yet. [ABSTRACT FROM AUTHOR]

In this study, we demonstrated a drastic improvement in energy resolution of (Lu0.75Y0.25)3Al5O12:Pr (LuYAG) single crystal scintillators from 4.8% to 4.1% at 662 keV upon Li+ codoping, which is the best value ever reported in the class of oxide single crystal scintillators. Li+ codoping can also significantly enhance its scintillation yield from 16 000 to 25 000 photons MeV−1, but slightly prolong the scintillation decay time. As Li+ codoping was found to have a negligible effect on the light yield non‐proportionality, we attributed the significant improvement in energy resolution to the reduced statistical variance in the number of photoelectrons produced in the photomultiplier tube (Rstat). [ABSTRACT FROM AUTHOR]

The implementation of nanocrystal-based composite scintillators as a new generation of ultrafast particle detectors is explored using ZnO:Ga nanopowder. Samples are characterized with a spectral-time resolved photon counting system and pulsed X-rays, followed by coincidence time resolution (CTR) measurements under 511 keV gamma excitation. Results are comparable to CTR values obtained using bulk inorganic scintillators. Bringing the ZnO:Ga nanocrystal's timing performance to radiation detectors could pave the research path towards sub-20 ps time resolution as shown in this contribution. However, an efficiency boost when placing nanopowders in a transparent host constitutes the main challenge in order to benefit from sub-nanosecond recombination times. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Despite recent intensive study on scintillators, several fundamental questions on scintillator properties are still unknown. In this work, we use ab-initio calculations to determine the energy dependent group velocity of the hot electrons from the electronic structures of several typical scintillators. Based on the calculated group velocities and optical phonon frequencies, a Monte-Carlo simulation of hot electron transport in scintillators is carried out to calculate the thermalization time and diffusion range in selected scintillators. Our simulations provide physical insights on a recent trend of improved proportionality and light yield from mixed halide scintillators. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Time-resolved luminescence properties of Ce3+ doped Y3Al5O12 (YAG) nanocrystals have been studied by means of vacuum-ultraviolet excitation spectroscopy. It was discovered that additionally to the regular Ce3+ yellow-green emission which is well-known luminescence in YAG, new emission covering a broad spectral range from 2.7 eV to 3.5 eV was revealed in the luminescence spectra for all YAG:Ce nanocrystals studied. This blue-UV emission has fast decay time about 7 ns as well as intensive well-resolved excitation band peaking at 5.9 eV and, in contrast to green Ce3+ emission, practically is not excited at higher energies. The origin of the blue-UV emission is tentatively suggested and discussed. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A novel approach is reported to minimize various defect centers in Ce doped Gd3Ga3Al2O12 single crystals to improve the scintillation properties. The crystals of Gd3Ga3Al2O12 codoped with 0.2 at% Ce and B (GGAG:Ce,B) have been grown in air and argon ambient using the Czochralski technique. The scintillation light output of crystals grown in Ar ambient was significantly increased after annealing the crystals in air. The measured light output of 60000 ph/MeV for annealed crystals is the highest value reported among this class of materials. As a consequence, the energy resolution at 662 keV gamma-rays from a 137Cs source was improved from 8% for the crystals grown in air to 6% for crystals grown in Ar and subsequently annealed in air. Further, the thermal quenching energy of photoluminescence (PL) emission was increased to be 470 meV for the annealed crystals. The thermoluminescence (TL) measurements suggest that the crystals grown in Ar ambient and post-growth annealed in air may have a lesser concentration of trap centers which subsequently lead to the improvement in optical and scintillation properties leading to a superior detector performance. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We report for the first time the optimized content and excellent scintillation properties of single crystalline film (SCF) scintillators of multicomponent Gd3- xLu x Al5- yGa y O12:Ce garnet compounds grown by liquid phase epitaxy (LPE) method. The Gd1.5Lu1.5Al2.75Ga2.25O12:Ce and Gd3Al2.75-2Ga2.25-3O12:Ce SCF show the light yield (LY) comparable with that of high-quality bulk crystal analogues of these garnets but faster scintillation decay and very low thermoluminescence in the above room temperature range. To our knowledge, these SCF possess the highest LY values ever obtained in LPE grown garnet SCF scintillators exceeding by at least 1.5-1.6 times the values previously reported for SCF scintillators. [ABSTRACT FROM AUTHOR]

Ce-doped Lu3Al5O12 optical ceramics co-doped with Mg2+ are fabricated by solid-state reaction method and further optimized by an air-annealing process. Mg2+ co-doping leads to a significant decrease of thermoluminescence intensity above room temperature and an increase of scintillation light yield (LY) value and fast component content even if the overall scintillation efficiency decreases. Scintillation LY of ∼21900 ph/MeV has been achieved with a short shaping time of 1 μs, and the ratio of LY values for 1 μs and 10 μs shaping times was as high as 79%. The acceleration of scintillation response induced by Mg2+ co-doping and the role of Ce4+ ions in the scintillation mechanism are discussed. [ABSTRACT FROM AUTHOR]

Optical and luminescence properties were studied in the Ce3+ doped yttrium and lutetium aluminum garnets (YAG, LuAG) admixed by Gd3+ and Ga3+ ions. The single crystalline films were grown by liquid phase epitaxy. Energy transfer from Gd3+ sensitizer to Ce3+ activator ions was established. This energy transfer was observed in a broad range of Gd concentrations which may point to longer range interaction between Gd3+ and Ce3+ ions. [ABSTRACT FROM AUTHOR]

We determine the thermal ionization energy of the excited state of Ce3+ in a SrHfO3 host by a contactless optical method based on the measurement and analysis of delayed recombination decay following UV excitation. We show the applicability of the method for microcrystalline powder samples. The method provides a consistent value of thermal ionization energy of about 0.25 eV, as previously determined by a ther- mally stimulated luminescence (TSL) study after UV illumination. We reveal a low temperature contribution to the delayed recombination signal and address its origin. This contribution indicates a complex interaction of the luminescence center with the host lattice neighborhood and the presence of temperature independent losses of fast scintillation light. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Several outstanding questions, including why complex halide scintillator host structures allow higher light yield and flatter electron energy response than simple monovalent metal halides, have remained unanswered by current models of luminescence in dense ionization tracks. Our measurements of nonlinear quenching kinetic order, recent literature on hot-electron transport in scintillators, and calculations presented here of hot-electron velocity from band structure of SrI2 and NaI, lead us to expand our previously described diffusion and nonlinear quenching model to include hot-electron transport. Trends in multivalent versus monovalent metal halides, heavier versus lighter halides, and halides versus oxides versus semiconductors can be predicted based on optical phonon frequency, thermalized band edge mobilities, velocity in the upper conduction bands, and hole self-trapping. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Scintillators are materials that absorb a high energy particle (α,β,γ radiation) and downconvert it into a short pulse of visible or near‐visible light. As determined by photon detection statistics, the ultimate energy resolution for γ‐photon detection can only be approached for materials that show a perfect proportional response with γ‐energy. A large amount of research has resulted in the discovery of highly proportional materials, such as SrI2:Eu2+ and CsBa2I5:Eu2+. However, the resolution is still limited because of unavoidable self‐absorption of Eu2+ emission, especially when large‐sized scintillators are to be used. By co‐doping with Sm2+, the emission of Eu2+ can be efficiently shifted to the far‐red by exploiting nonradiative energy transfer. Herein, this new idea is applied to CsBa2I5, and Sm co‐doped CsBa2I5:Eu2+ can be considered as the first "black scintillator" with an emission wavelength around 755 nm, a remarkable high energy resolution of 3.2% at 662 keV gamma excitation, and a scintillation decay time of 2.1 μs. The proposed double‐doping principle can be used to develop an entirely new class of near‐infrared (NIR) scintillators. [ABSTRACT FROM AUTHOR]

Commercially available Lu2SiO5:Ce (LSO:Ce) scintillators for the nuclear medical imaging applications, such as positron electron tomography (PET), normally have a light yield of 30 000–32 000 photons/MeV and a scintillation decay time of 43–45 ns. We demonstrate a simultaneous improvement of light yield and decay time of LSO:Ce single crystal scintillators with lithium codoping. Li codoping significantly enhances the light yield of LSO:Ce from 32 500 to 39 000 photons/MeV, shortens the scintillation decay time from 45.4 to 42.1 ns, and reduces the room temperature afterglow by around one order of magnitude. The physical insights on the role of Li codopants in scintillation mechanism are provided by studying cerium oxidation state, luminescence properties of cerium activator centers, defect structure, and preferential occupation of lithium ions. The improved light yield and afterglow are explained in terms of the dissociation of spatially correlated oxygen vacancies (VO) and Ce centers or the suppression of VO formation, allowing a more efficient electron migration to Ce centers. We attribute the decay time shortening upon Li+ codoping to the reduction of slow Ce2 emissions via a non‐radiative energy transfer from six‐coordinated Ce2 to seven‐coordinated Ce1 centers. This letter reports a simultaneous improvement of light yield, decay time, and afterglow of Lu2SiO5:Ce3+ scintillation detectors by Li+ codoping. Analysis reveals the non‐conversion of stable Ce3+ to Ce4+ upon Li codoping, and the critical role of Li site occupancy on the suppression of oxygen vacancies. This strategy is also expected to be extended to other oxide scintillators. [ABSTRACT FROM AUTHOR]