Tunable Radioluminescence Perovskite Nanocrystal Scintillators

In recent years, the increasing demand of various fields of radiation detection materials has led to intensive researches in scintillation materials 1-2]. The scintillators can absorb high-energy X-ray photons and then convert them into low-energy visible photons, which are widely applied in radiation monitoring, security detection, X-ray astronomy and medical radiology 3"l].

Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

Nanosized cerium-doped lutetium aluminum garnet （LuAG：Ce） phosphors were prepared by nitrate-citrate solgel combustion process using 1：1 ratio of the citrate：nitrate. The prepared LuAG：Ce phosphors were characterized by XRD, TEM, photoluminescence and radioluminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG：Ce was obtained at 900 ℃ by directly crystallizing from amorphous materials. The resultant Lu- AG：Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 urn. Both photoluminescence and radioluminescence were well-known Ce^3＋ emissions located in the range of 470 -600 nm consisting of two emission bands because of the transition from the lowest 5d excited state （2D） to the 4f ground state of Ce^3＋, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.

具有高效发光性能的亚铜卤化物纳米团簇应用于X-射线闪烁体

闪烁体可以将高能辐射转化为可见光,作为一种光电功能材料已经广泛应用于各种放射探测领域.虽然三维Pb基钙钛矿纳米晶可以开发为X射线闪烁体材料,但是其较低的光产额和铅毒性问题在一定程度上限制了其应用.为解决这一问题,本文重点关注零维金属卤化物发光材料,合成了一系列基于孤立[Cu_(4)X_(6)]^(2−)纳米团簇的零维卤化物,并将其开发应用为闪烁体发光材料.在紫外线或蓝光激发下,该卤化物纳米团簇均显示出宽带光发射,发光颜色可覆盖绿色、橙色到红色,并且具有近乎100%的光量子产率和较大的Stokes位移(>1.3 eV).特别突出的是,该类卤化物纳米团簇由于较高的发光量子产率、较小的光学自吸收和较强的X射线衰减效率,表现出优异的X-射线闪烁发光性能,光产额最高可达到24,240 photons MeV−1.材料的闪烁发光强度与X射线剂量呈现线性关系,检测范围较宽,且检测极限(0.7563μGy_(air)s^(−1))远低于常规医学诊断所要求的计量(5.5μGy_(air)s^(−1)).X-射线成像结果表明该纳米团簇余晖衰减时间较短(1.3 ms),空间分辨率较高(14.83 lp mm^(−1)),在医学成像等领域具有潜在的应用价值.该项工作表明,亚铜卤化物纳米团簇具有高效、稳定、无毒、发光效率高等优点,有望成为一种优异的新型闪烁体发光材料.

Recent advances,challenges,and opportunities of inorganic nanoscintillators

This review article highlights the exploration of inorganic nanoscintillators for various scientific and technological applications in the fields of radiation detection,bioimaging,and medical theranostics.Various aspects of nanoscintillators pertaining to their fundamental principles,mechanism,structure,applications are briefly discussed.The mechanisms of inorganic nanoscintillators are explained based on the fundamental principles,instrumentation involved,and associated physical and chemical phenomena,etc.Subsequently,the promise of nanoscintillators over the existing single-crystal scintillators and other types of scintillators is presented,enabling their development for multifunctional applications.The processes governing the scintillation mechanisms in nanodomains,such as surface,structure,quantum,and dielectric confinement,are explained to reveal the underlying nanoscale scintillation phenomena.Additionally,suitable examples are provided to explain these processes based on the published data.Furthermore,we attempt to explain the different types of inorganic nanoscintillators in terms of the powder nanoparticles,thin films,nanoceramics,and glasses to ensure that the effect of nanoscience in different nanoscintillator domains can be appreciated.The limitations of nanoscintillators arc also highlighted in this review article.The advantages of nanostructured scintillators,including their property-driven applications,are also explained.This review article presents the considerable application potential of nanostructured scintillators with respect to important aspects as well as their physical and application significance in a concise manner.

Revisiting an ancient inorganic aggregation-induced emission system:An enlightenment to clusteroluminescence

Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood.Here,we employed a series of ancient inorganic complexes platinocyanides with aggregation-induced emission property to elucidate the mechanism of clusteroluminescence including how does the chromophore form and how does the solid structures influence the luminescence behaviors.The results indicate that the isolated platinocyanide cannot work as a chromophore to emit visible light,while their clusterization at aggregate state can trigger the d-orbitals coupling of the platinum atoms to facilitate the electron exchange and delocalization to form a new chromophore to emit visible light.Furthermore,the counter ions and H2O ligands help to rigidify the three-dimensional network structure of the platinocyanides to suppress the excited state nonradiative decay,resulting in the high quantum yield of up to 96%.This work fundamentally helps understanding both the organic and inorganic clusteroluminescence phenomenon.

Organic room-temperature phosphorescent polymers for efficient X-ray scintillation and imaging

Materials that exhibit visible luminescence upon X-ray irradiation show great potential in the medical and industrial fields.Pure organic materials have recently emerged as promising scintillators for X-ray detection and radiography,due to their diversified design,low cost,and facile preparation.However,recent progress in efficient radioluminescence has mainly focused on small molecules,which are inevitably associated with processability and repeatability issues.Here,a concise strategy is proposed to prepare radioluminescent polymers that exhibit multiple emission colors from blue to yellow with high brightness in an amorphous state by the radical copolymerization of negatively charged polyacrylic acid and different positively charged quaternary phosphonium salts.One of the obtained polymers exhibits excellent photostability under a high X-ray irradiation dosage of 27.35 Gy and has a detection limit of 149 nGy s^(−1).This performance is superior to that of conventional anthracene-based scintillators.Furthermore,by simply drop-casting a polymer methanol solution on a quartz plate,a transparent scintillator screen was successfully fabricated for X-ray imaging with a resolution of 8.7 line pairs mm^(−1).The pure organic phosphorescent polymers with a highly efficient radioluminescence were demonstrated for the first time,and the strategy reported herein offers a promising pathway to expand the application range of amorphous organic scintillators.