Excellent Scintillation Research Articles

Optical Properties and Application Development of Glass-Ceramics

Due to the excellent optical properties, glass ceramics are widely used in LED lighting, optical information storage, and other fields. However, the nucleation and growth process of nanocrystals in amorphous glass media is still unclear as to the key to the subjective control of optical properties and its application development. Herein, we propose a real-time in situ TEM imaging method to study the nanocrystal nucleation growth kinetics in amorphous glass media. The results reveal the missing mystery of the nucleation kinetics of amorphous nanoclusters. By directly observing the crystallization process of nanocrystals, the coexistence of the non-classical nucleation theory and the classical nucleation theory was confirmed, and the subjective regulation of the optical properties of glass-ceramics was realized. Based on the excellent optical properties of the optimized glass-ceramic, its application in up-conversion laser, laser refrigeration, short-wave shielding, and other fields has been further realized. Quantum dots with excellent scintillation performance are embedded in the glass to obtain a transparent and uniform composite material. The three-dimensional network structure of the glass ensures its scintillation performance while giving it excellent physical and chemical stability, realizing low-dose high-resolution X-ray imaging, and realizing Repairable after high-dose radiation damage. A trap center and an efficient luminescence center are constructed in the glass to realize mechanoluminescence, and the passive self-driven fiber stress sensing is realized by coupling the optical waveguide effect of the highly transparent glass fiber.

Controllable Multi‐Exciton Zero‐Dimensional Antimony‐Based Metal Halides for White‐light Emission and β‐Ray Detection

AbstractSelf‐trapped exciton (STE) emission, typified by antimony (Sb), with broadband characteristics, represents the next generation of materials for solid‐state lighting and radiation detection. However, little is known about the multiexciton behavior of the Sb emission center. Here, we proposed a general approach for designing antimony‐centered multi‐exciton emitting materials through self‐assembly. Benefitting from controllable multiexciton behavior, dual‐band white light emission spanning the entire visible spectrum was achieved. Relying on the reduction of an effective atomic number brought by self‐assembly, excellent scintillation response to β‐rays was attained. This study offers unprecedented insight into hybrid single/triple STE emission and unveils new avenues for single‐emitter white‐light emission, as well as radiographic testing using low‐risk β‐rays as sources.

Controllable Multi-Exciton Zero-Dimensional Antimony-Based Metal Halides for White-light Emission and β-Ray Detection.

Self-trapped exciton (STE) emission, typified by antimony (Sb), with broadband characteristics, represents the next generation of materials for solid-state lighting and radiation detection. However, little is known about the multiexciton behavior of the Sb emission center. Here, we proposed a general approach for designing antimony-centered multi-exciton emitting materials through self-assembly. Benefitting from controllable multiexciton behavior, dual-band white light emission spanning the entire visible spectrum was achieved. Relying on the reduction of an effective atomic number brought by self-assembly, excellent scintillation response to β-rays was attained. This study offers unprecedented insight into hybrid single/triple STE emission and unveils new avenues for single-emitter white-light emission, as well as radiographic testing using low-risk β-rays as sources.

Rod‐Like Microcrystal Scintillators Based on Organic–Inorganic Hybrid Copper Halides for X‐Ray Imaging

AbstractCopper‐based organic–inorganic hybrid halides (OIHHs) have garnered significant interest in X‐ray imaging due to their flexible structural adjustability, efficient light emission, strong X‐ray absorption, etc. Herein, four copper‐based OIHH crystals composed of the same organic ligands (isopropyl triphenylphosphonium cations, IPP+) and inorganic parts (Cu2I42−) are synthesized by varying the ratios of raw materials and types of reaction solvents. Although these crystals share identical structures, they exhibit different luminescent behaviors (blue, green, white, and yellow) attributed to vacancy defects originating from CuI. Notably, the novel copper‐based OIHH (CP2) with green emission shows the best luminescence efficiency (99.54%) and excellent scintillation performance (50675 photons MeV−1). The traditional technology of scintillation screens mixing scintillator powders and polymers often results in light scattering due to powder aggregation and inhomogeneity. To address this challenge, the dispersant polyvinyl pyrrolidone is introduced to prepare uniform rod‐like microcrystals of CP2. The scintillation screen based on CP2 microcrystals achieves a high spatial resolution of 16–18 lp mm−1, surpassing the resolution of most copper‐based OIHH scintillators. Furthermore, it is imaging capabilities are validated using a commercial X‐ray flat panel detector, demonstrating imaging performance comparable to that of commercial scintillators.

Enhanced scintillating performance in Tb3+ doped oxyfluoride glass for high-resolution X-ray imaging

Scintillators that exhibit excellent scintillation performance coupled with superior radiation resistance are anticipated to cater the growing demand of X-ray detection across various fields including medicine and scientific research. Oxyfluoride glasses, which combine the benefits of both fluorine and oxide glasses, show significant potential as scintillator candidates. Here, highly transparent Tb3+ doped oxyfluoride glasses with splendid radioluminescence were successfully synthesized by melt quenching method with the aid of a two-step component tuning strategy. The luminescence excited by X-ray and ultraviolet light are significantly enhanced by boosting the effective atomic number of glass components and optimizing the B2O3/Al2O3 ratio. The integrated X-ray excited luminescence intensity of representative specimen reaches 219% of that of BGO. Exceptional anti-irradiation recoverability and thermal stability of 93% @ 573 K are conferred in the resultant glass. Moreover, X-ray imaging with a spatial resolution of up to 20 lp mm−1 was triumphantly achieved. These properties testify that the prepared oxyfluoride glass owns an enormous application foreground in X-ray imaging.

Vacuum-filtration fabrication of copper-based halide scintillation screen for high-resolution X-ray imaging

Zero-dimensional (0D) organic-inorganic Cu(I)-based halides have garnered significant attention due to their low toxicity, efficient emission, and moderate fabrication conditions. However, the challenge remains in developing stable and efficient 0D hybrid Cu(I)-based halides for effective X-ray imaging. In this study, a yellow-emitting 0D hybrid copper halide, (ETPP)2Cu2I4 (Ethyl triphenylphosphonium, ETPP), was successfully synthesized via a slow evaporation method. This compound demonstrated an impressive steady-state light yield of 23,200 photons/MeV under X-ray radiation and an ultralow detection limit of 150.9 nGyair s−1, approximately 35 times lower than the standard medical examination dosage. Utilizing a vacuum-filtration method, we fabricated a flexible film that outperforms traditional methods and achieved an exceptional X-ray imaging resolution of 16.0 lp/mm. This study introduces a novel approach to fabricating high-performance X-ray imaging scintillators based on 0D Cu-based halides, showcasing excellent scintillation performance and stability for non-destructive testing.

Investigation of optical properties of Ce and Eu-doped Gd2SiO5 insights from GGA + U calculations

Gadolinium silicate, (Gd2SiO5) co-doped with Ce and Eu has been found to exhibit enhanced luminescence efficiency, which makes it a promising material for use in scintillators and phosphors. It has excellent scintillation properties such as high density and high Zeff. In this study, we used density functional theory (DFT) calculations within the Wien2k software to investigate the effect of Ce and Eu concentration and native defects on the electronic structure and optical properties of Ce and Eu co-doped Gd2SiO5. We utilized the DFT + U method to treat the localized 4f electrons of Ce and Eu. Our results indicate that the electronic structure and optical properties of Ce and Eu co-doped Gd2SiO5 are significantly affected by the concentration of the dopants and presence of native defects. We found that increasing the concentration of Ce and Eu dopants leads to a shift in the bandgap to lower energies, resulting in enhanced absorption and emission spectra. Moreover, our calculations reveal that presence of oxygen vacancies and Gd interstitials can induce new defect levels in the bandgap, which may affect the luminescence properties of the material. Our study provides valuable insights into the atomic-level mechanisms that govern the luminescence properties of Ce and Eu co-doped Gd2SiO5 which can aid in the design and optimization of luminescent materials for various applications.

Phosphonium Iodide Featuring Blue Thermally Activated Delayed Fluorescence for Highly Efficient X‐Ray Scintillator

AbstractOrganic scintillators are praised for their abundant element reserves, facile preparation procedures, and rich structures. However, the weak X‐ray attenuation ability and low exciton utilization efficiency result in unsatisfactory scintillation performance. Herein, a new family of highly efficient organic phosphonium halide salts with thermally activated delayed fluorescence (TADF) are designed by innovatively adopting quaternary phosphonium as the electron acceptor, while dimethylamine group and halide anions (I−) serve as the electron donor. The prepared butyl(2‐[2‐(dimethylamino)phenyl]phenyl)diphenylphosphonium iodide (C4‐I) exhibits bright blue emission and an ultra‐high photoluminescence quantum yield (PLQY) of 100 %. Efficient charge transfer is realized through the unique n‐π and anion‐π stacking in solid‐state C4‐I. Photophysical studies of C4‐I suggest that the incorporation of I accounts for high intersystem crossing rate (kISC) and reverse intersystem crossing rate (kRISC), suppressing the intrinsic prompt fluorescence and enabling near‐pure TADF emission at room temperature. Benefitting from the large Stokes shift, high PLQY, efficient exciton utilization, and remarkable X‐ray attenuation ability endowed by I, C4‐I delivers an outstanding light yield of 80721 photons/MeV and a low limit of detection (LoD) of 22.79 nGy ⋅ s−1. This work would provide a rational design concept and open up an appealing road for developing efficient organic scintillators with tunable emission, strong X‐ray attenuation ability, and excellent scintillator performance.

Phosphonium Iodide Featuring Blue Thermally Activated Delayed Fluorescence for Highly Efficient X-Ray Scintillator.

Organic scintillators are praised for their abundant element reserves, facile preparation procedures, and rich structures. However, the weak X-ray attenuation ability and low exciton utilization efficiency result in unsatisfactory scintillation performance. Herein, a new family of highly efficient organic phosphonium halide salts with thermally activated delayed fluorescence (TADF) are designed by innovatively adopting quaternary phosphonium as the electron acceptor, while dimethylamine group and halide anions (I-) serve as the electron donor. The prepared butyl(2-[2-(dimethylamino)phenyl]phenyl)diphenylphosphonium iodide (C4-I) exhibits bright blue emission and an ultra-high photoluminescence quantum yield (PLQY) of 100 %. Efficient charge transfer is realized through the unique n-π and anion-π stacking in solid-state C4-I. Photophysical studies of C4-I suggest that the incorporation of I accounts for high intersystem crossing rate (kISC) and reverse intersystem crossing rate (kRISC), suppressing the intrinsic prompt fluorescence and enabling near-pure TADF emission at room temperature. Benefitting from the large Stokes shift, high PLQY, efficient exciton utilization, and remarkable X-ray attenuation ability endowed by I, C4-I delivers an outstanding light yield of 80721 photons/MeV and a low limit of detection (LoD) of 22.79 nGy ⋅ s-1. This work would provide a rational design concept and open up an appealing road for developing efficient organic scintillators with tunable emission, strong X-ray attenuation ability, and excellent scintillator performance.

Organic‐Inorganic Cuprous Halides With Reversible Photoluminescence for Multiple Optical Applications

Abstract0D organic‐inorganic Cu(I)‐based halides have gained significant attention due to their low toxicity, structural adjustability, and moderate fabrication conditions. However, it is still challenging to explore stable and efficient 0D hybrid Cu(I)‐based halides that have phase transition and tunable spectra for multifunctional photoelectric applications. Herein, two 0D copper halides, green‐emissive (MTPP)2CuI3 and yellow‐emissive (MTPP)2Cu4I6(MTPP = Methyltriphenylphosphonium), are successfully synthesized using a slow cooling method. Both compounds exhibit high photoluminescence quantum yield (PLQY) of 81.95 and 99.7%, and remarkable steady‐state light yield of 38 750 and 63 700 photons per MeV, respectively. The scintillation screen of the two compounds based on vacuum‐filtration enables high X‐ray imaging resolution of 17.83 and 18.49 lp mm−1, showing great potential in practical X‐ray imaging applications. Moreover, a reversible and fast phase transformation between them occurs when stimulated by ethanol or MTPP solutions, without requiring additional thermal treatment, which endows them with a high level of anti‐counterfeiting under room temperature (RT). It is worth noting that they display remarkable resistance to water, maintaining its phase purity even after being immersed in water for 30 days. This study introduces a new approach to investigate the 0D Cu‐based halides that exhibit excellent scintillation performance, stability, and efficient photoluminescence tunability for multiple applications.

In Situ Growth of Lead‐Free Double Perovskite Micron Sheets in Polymethyl Methacrylate for X‐Ray Imaging

AbstractPb‐free double‐perovskite (DP) scintillators are highly promising candidates for X‐ray imaging because of their superior optoelectronic properties, low toxicity, and high stability. However, practical applications require Pb‐free DP crystals to be ground and mixed with polymers to produce scintillator films. Grinding can compromise film uniformity and optical properties, thereby affecting imaging resolution. In this study, an in situ fabrication strategy is proposed to facilitate the crystalline growth of Pb‐free Cs2AgInxBi1‐xCl6 micron sheets in polymethyl methacrylate in a single step. By adjusting the In3+/Bi3+ ratio, Cs2AgIn0.9Bi0.1Cl6/PMMA composite films (CFs) with excellent scintillation properties are obtained, including a light yield of up to 32000 photons per MeV and an X‐ray detection limit of 87 nGyairs−1. This strategy also enabled the production of large Cs2AgIn0.9Bi0.1Cl6/PMMA CFs, which demonstrated favorable flexibility and stability, fabricating products with advanced eligibility for commercial applications. The CFs exhibited outstanding performances in X‐ray imaging, producing high‐resolution structures and providing a new avenue for the development of Pb‐free DP materials in fields such as medical imaging and safety detection.

Thermal stability and flexible X-Ray scintillation screen through in-situ assembling Cs3Cu2Cl5 nanocrystals in polymer matrix

Copper-based halides have emerged as promising scintillator materials for X-ray imaging, attributed to their favorable photophysical characteristics, such as negligible self-absorption, high light output, and fast decay. Within this category of materials, Cs3Cu2Cl5 composite polymer scintillator films stand out, delivering excellent performance as flexible X-ray detector screens. However, severe scattering and light degradation induced by the inevitable agglomeration during recombination restricted the application in high-resolution and flexible X-ray imaging. In this study, a Cs3Cu2Cl5@PMMA film prepared by in-situ growth strategy is successfully developed, which represents uniform area, adjustable flexibility and excellent scintillation performance. The prepared large-area film exhibits green emission at 527 nm, with a high light yield, low detection limit and excellent spatial resolution. Meanwhile, the Cs3Cu2Cl5@PMMA film exhibits a remarkable degree of flexibility, enabling imaging applications on non-planar surfaces. Furthermore, it also demonstrates excellent resistance to high temperature environment, maintaining its high-quality imaging performance at 403 K.

Bivalent metal ion co-doped methylammonium lead tribromide perovskite nanocrystal scintillator for X-ray imaging

Perovskite scintillators with low cost, easy preparation, environmental stability, and high-resolution have become candidates for X-ray imaging applications. Here, based on the calculation results of surface formation energy (Ef) and vacancy defect energy (Evac), a series of co-doped perovskite nanocrystals (NCs) with photoluminescence high quantum yield (PLQY) and fast luminescence decay time had been prepared by doping several bivalent metal ions into the B-site of methylammonium lead tribromide (MAPbBr3). In addition, the scintillator with flexibility was prepared using poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as the carrier, showing excellent stability and scintillation performance, with a light yield of 21,200 photons/MeV, imaging resolution reached 11.7 lp/mm, and low detection limits of 462 nGyair s−1. Finally, we demonstrated the scintillator characteristic with high-quality imaging results and excellent tolerance under high dose rate X-ray (25 mGy s−1). Therefore, the combination of co-doped nanocrystals with excellent optical properties and PVDF-HFP further paves the way for the development of a scintillator.

A Thermo-Responsive MOFs for X-Ray Scintillator.

Thermo-responsive smart materials have aroused extensive interest due to the particular significance of temperature sensing. Although various photoluminescent materials are explored in thermal detection, it is not applicable enough in X-ray radiation environment where the accuracy and reliability will be influenced. Here, a strategy is proposed by introducing the concept of radio-luminescent functional building units (RBUs) to construct thermo-responsive lanthanide metal-organic frameworks (Ln-MOFs) scintillators for self-calibrating thermometry. The rational designs of RBUs (including organic ligand and Tb3+/Eu3+) with appropriate energy levels lead to high-performance radio-luminescence. Ln-MOFs scintillators exhibit perfect linear response to X-ray, presenting low dose rate detection limit (min ≈156.1 nGyairs-1). Self-calibrating detection based on ratiometric XEL intensities is achieved with good absolute and relative sensitivities of 6.74 and 8.1%K-1, respectively. High relative light yield (max ≈39000 photons MeV-1), imaging spatial resolution (max ≈18 lpmm-1), irradiation stability (intensity ≈100% at 368 K in total dose up to 215 Gyair), and giant color transformation visualization benefit the applications, especially the in situ thermo-responsive X-ray imaging. Such strategy provides a promising way to develop the novel smart photonic materials with excellent scintillator performances.

Unveiling the effect of hypophosphorous acid for the growth of high quality Cs3Cu2I5 single crystals

The zero-dimensional copper halide perovskite Cs3Cu2I5 displays extraordinary luminescence and scintillation characteristics, and high-quality crystals are extremely desirable for exploring the commercial applications. Currently, the most critical issue in the solution growth of Cs3Cu2I5 crystals is the easy oxidation of halides, which significantly hinders the optimization of crystal qualities. The hypophosphorous acid (H3PO2) has been applied to inhibit the oxidation, nevertheless, the related mechanism is elusive and has been largely ignored. Herein, Cs3Cu2I5 crystals have been grown from N, N-Dimethylformamide (DMF) solvent by the antisolvent vapor-assisted crystallization (AVC) method. It is verified that H3PO2 effectively prevents the oxidation of Cs3Cu2I5 by rapidly reducing Cu2+ and I3−, maintaining the stability of the precursor solution and continuously suppressing oxidation during the whole growth process. Meanwhile, by increasing the acidity of the solution, H3PO2 dissolve precursor colloids and efficiently enhance the solubility of halides. Thus, the addition of H3PO2 favors the rapid growth of centimeter-sized Cs3Cu2I5 crystals with well-defined crystallographic planes within several days. As excellent gamma ray scintillator, the crystal exhibits high light yield of 38000 photons/MeV, with energy resolution of 5.6 % under 662 keV radiation from a 137Cs source. This work deeply elucidates new insight into the critical effect of H3PO2 in the DMF based solution crystal growth, facilitating the preparation of large-size and high-performance copper halide perovskite crystals.

Near‐unity broadband emissive hybrid manganese bromides as highly‐efficient radiation scintillators

AbstractZero‐dimensional (0D) hybrid manganese halides have gained wide attention for the various crystal structures, excellent optical performance and scintillation properties compared with 3D lead halide perovskite nanocrystals. In this work, a new family of 0D hybrid manganese halides of A2MnBr4 (A = BzTPP, Br‐BzTPP, and F‐BzTPP) based on discrete [MnBr4]2− tetrahedral units is reported as highly efficient lead‐free scintillators. Excited by UV or blue light, these hybrids emit bright green light originating from the d–d transition of Mn2+ with near‐unity PLQY (99.5%). Significantly, high PLQY and low self‐absorption render extraordinary radioluminescence properties with the highest light yield of 80,100 photons MeV−1, which reached the climax of present hybrid manganese halides and surpassed most commercial scintillators. The radioluminescence intensity features a linear response to X‐ray doses with a detection limit of 30 nGyair s−1, far lower than the requirement of medical diagnostic (5.5 µGyair s−1). X‐ray imaging demonstrates ultrahigh spatial resolution of 14.06 lp mm−1 and short afterglow of 0.3 ms showcasing promising application prospects in radiography. Overall, we demonstrated new hybrid manganese halides as promising scintillators for advanced applications in X‐ray imaging with multiple superiorities of nontoxicity, facile‐assembly process, high irradiation light yield, excellent resolution, and stability.

Fabrication and Properties for Thermal Neutron Detection of 6LiCl/Rb2CeCl5 Eutectic Scintillator

The 3He gas is commonly used for the detection of thermal neutrons. However, with the depletion of 3He gas, there is a need to develop new solid scintillators for thermal neutron detection. Solid scintillators containing 6Li, which have large neutron capture cross-sections and a large amount of energy released by transmutation reactions, are commonly used as alternative candidates. However, only single-crystal scintillators are currently used, and their 6Li concentration is limited by their chemical composition. In this study, we designed, grew, and evaluated a new eutectic scintillator, Rb2CeCl5/LiCl, which can improve the 6Li concentration compared with single-crystal scintillators. Rb2CeCl5, which was selected as the scintillator phase, has excellent scintillator properties (light yield: 36,000 photons/MeV, decay time: mostly 24 ns, slightly 153 ns), and is less deliquescent than other halide scintillators. The crystal grown using the vertical Bridgman method exhibited a eutectic phase composed of Rb2CeCl5 and LiCl. The eutectic crystals exhibited Ce3+ 5d-4f emissions, with a peak between 360 and 370 nm. The Rb2CeCl5 phase was identified as the luminescent phase via cathodoluminescence mapping, and 16,000 photons/neutron of the light yield and 56.1 ns of the decay time were observed. This study indicates that the Rb2CeCl5/LiCl eutectic scintillator is a promising candidate for use in thermal neutron detectors.

Yellow-emissive organic copper(i) halide single crystals with [Cu4I4] cubane unit as efficient X-ray scintillators

The (4-bzpy)4Cu4I4 compound exhibits excellent X-ray scintillation properties with a high light yield and great potential in X-ray imaging applications.

R&D of glass scintillator for nuclear radiation detection

In 2021, the Institute of High Energy Physics proposed a design of glass scintillator coupled with SiPM as a new solution for the next generation calorimeter, to explore the application of glass scintillators in high energy physics and nuclear radiation detection. The Large Area Glass Scintillator Collaboration Group was established to research and develop a glass scintillator with high density, high light yields and fast decay time. Through continuous optimization, the glasses have excellent scintillation performance with a light yield of 1000 ph/MeV and a density of 6 g/cm3. Moreover, the neutron response of the glasses was investigated, and different high-energy particles can be distinguished by signal amplitude. In addition, the radiation resistance of different glasses was tested under proton beam. All the glasses appeared opaque and produced a high radioactive background, because Gd element interacts with proton to produce radionuclides with high activity and long half-life.

Halogen-bonding boosting the high performance X-ray imaging of organic scintillators.

Organic scintillators with efficient X-ray excited luminescence are essential for medical diagnostics and security screening. However, achieving excellent organic scintillation materials is challenging due to low X-ray absorption coefficients and inferior radioluminescence (RL) intensity. Herein, supramolecular interactions are incorporated, particularly halogen bonding, into organic scintillators to enhance their radioluminescence properties. By introducing heavy atoms (X=Cl, Br, I) into 9,10-bis(4-pyridyl)anthracene (BPA), the formation of halogen bonding (BPA-X) enhances their X-ray absorption coefficient and restricts the molecular vibration and rotation, which boosts their RL intensity. The RL intensity of BPA-Cl and BPA-Br fluorochromes increased by over 2 and 6.3 times compared to BPA, respectively. Especially, BPA-Br exhibits an ultrafast decay time of 8.25ns and low detection limits of 25.95±2.49nGys-1. The flexible film constructed with BPA-Br exhibited excellent X-ray imaging capabilities. Furthermore, this approach is also applicable to organic phosphors. The formation of halogen bonding in bromophenyl-methylpyridinium iodide (PYI) led to a fourfold increase in RL intensity compared to bromophenyl-methyl-pyridinium (PY). It suggests that halogen bonding serves as a promising and effective molecular design strategy for the development of high-performance organic scintillator materials, presenting new opportunities for their applications in radiology and security screening.