Effect of annealing atmospheres on the scintillation properties of Ce^(3+)‑doped YAG nanoscintillator

Background In this study,three sample detectors have been prepared by using cerium-activated YAG nanoscintillator(Y_(3)Al_(5)O_(12):Ce^(3+))synthesized by sol-gel method and heat-treat at 900°C for 2 h in different atmospheres such as vacuum,air and nitrogen.Purpose Many studies about YAG:Ce^(3+)single crystal have been carried out,but the material at the nanoscale remains not enough understood.The objective of the present paper is to investigate the effects of annealing atmosphere on the scintillation properties and identify the suitable atmosphere that allow to design radiation detectors with high scintillation efficiency.Methods In order to accurately assess the scintillation properties,the nanoscintillator sample powders have been designed as a detector,in which,preparation operations such as surface homogenization and efficiency coupling with photomultiplier tube(PMT)window were developed.The study was performed usingγ-rays 662 keV released from137Cs radioactive source,the bi-alkali GDB-4FF PMT was used as a photodetector.Nuclear instrumentation chain was set up in order to collect the pulse height spectra,NaI:Tl single-crystal scintillator was used as a reference detector to estimate the scintillation light yield.The delayed coincidence method was used for measuring the scintillation decay time of nanoscintillator sample detectors.Results The sample detector annealed at vacuum atmosphere exhibits the best scintillation properties,the scintillation light yield was estimated to be 14,600±3400 ph/MeV and the fast component in the scintillation decay was 90 ns.Conclusion The vacuum is the suitable atmosphere which allows the development of radiation detectors with high scintillation efficiency.

Enhancing light yield of Tb^(3+)-doped fluoride nanoscintillator with restricted positive hysteresis for low-dose high-resolution X-ray imaging

Developing scintillators with high light yield(LY),superior irradiation stability,and weak afterglow is of significance for the realization of low-dose high-resolution X-ray excited optical luminescence(XEOL)imaging.Lanthanide doped fluoride nanoparticles possess low toxicity,superior environmental stability,facial fabrication process,and tunable emissions,which are appropriate candidates for the next generation nanoscintillators(NSs).However,the low LY and strong positive hysteresis greatly restrict their practical application.Here,we propose an effective strategy that engineers energy gap to significantly enhance the LY.Our results verify that the tetragonal LiLuF4 host benefits the crystal level splitting of Tb^(3+)ions,which greatly promotes the electrons population on the Tb^(3+):5D4 level followed by the enhanced LY.The LY of LiLuF4:Tb@LiLuF4 NSs is calculated to be~31,169 photons/MeV,which is much higher than the lead halide perovskite colloidal CsPbBr3(~21,000 photons/MeV)and LuAG:Ce(~22,000 photons/MeV)scintillators.Moreover,the positive hysteresis is remarkably restricted after coating a thin shell.The X-ray detection limit and spatial resolution are measured to be~21.27 nGy/s and~7.2 lp/mm,respectively.We further verify that this core/shell NS can be employed as scintillating screen to realize XEOL imaging under the low dose rate of 13.86μGy/s.Our results provide an effective route to develop high performance NSs,which will promote great opportunities for the development of low-dose high-resolution XEOL imaging devices.

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.

高效X射线紫外发光稀土纳米闪烁体及其活体X射线激活肿瘤治疗应用

基于X射线纳米闪烁体的光响应疗法是一种新兴的有良好应用前景的活体肿瘤治疗策略,迫切需要开发具有高效X射线激发紫外发光性能的纳米闪烁体.然而,由于当前纳米闪烁体的X射线紫外发光性能仍较弱,实现高效的X射线激活肿瘤治疗仍然是一个巨大的挑战.为此,我们发展了一种新型的具有良好X射线紫外发光性能的Gd^(3+)/Ce^(3+)共掺杂的LiLuF4纳米闪烁体,并将其应用于活体肿瘤治疗.通过优化基质材料、掺杂剂和能量传递设计合成的纳米闪烁体,其X射线紫外发光强度比传统的Ce^(3+)单掺杂材料增强了约18倍.我们进一步将纳米闪烁体与一氧化氮(NO)前体结合以概念验证研究纳米闪烁体的应用.在X射线照射下,该纳米复合物能够可控地产生NO,并在X射线诱导的NO和放射治疗协同作用下实现了优异的抗肿瘤效果.此外,X射线激活的NO治疗可以抑制肿瘤向肝脏转移,抑制肿瘤再生,延长小鼠存活率.这项工作有望推动纳米闪烁体的发展及其在活体深层组织疾病治疗中的应用.