X射线激发发射光谱仪的设计及实现

基于时间相关单光子计数原理的探测系统,设计并实现了一种新型的X射线激发发射光谱仪,以有效探测高能X射线激发闪烁体的发光强度(尤其是微弱的发光)及相关的余辉特性测量。通过对常见的Cs I(Tl)、LYSO(Ce)闪烁晶体和Tb3+激活硅酸盐闪烁玻璃等的测试结果表明,所研制的X射线激发发射光谱仪能很好地满足闪烁材料的研发需要。

Preparation of Gd_2O_2S:Pr Scintillation Ceramics by Pressureless Reaction Sintering Method

Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothermal reaction using commercially available Then single phase Gd2O2SO4：Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4：Pr powder compacts can be sintered to single phase Gd2O2S：Pr ceramics with a relative density of 99% and mean grain size of 30um at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S：Pr ceramics were examined. Luminescence spectra of the Gd2O2S：Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ^3p0-3H4 transition of Pr^3＋ ions.

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.

红色荧光粉YF_3:Eu^(3+),Gd^(3+)的制备及发光性能

采用水热法合成了YF_3:xEu^(3+)和YF_3:0.14Eu^(3+),0.08Gd^(3+)系列荧光粉。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、光电子能谱(EDS)、光致发光(PL)和长余辉光谱分别对样品的物相、结构、形貌、表面元素、PL和荧光寿命进行了表征。XRD检测表明,合成的样品属正交晶系。ED数据验证了合成样品的表面元素组分。PL光谱测试表明,YF_3:xEu^(3+)的激发光谱由200~300nm的宽带和Eu^(3+)的系列窄带激发峰组成,YF_3:0.14Eu^(3+),0.08Gd^(3+)的激发光谱由200~300nm的宽带和Eu^(3+),Gd^(3+)的系列窄带激发峰组成。在319nm紫外光激发下,测得YF_3:xEu^(3+)材料的发射光谱为一个多峰谱,主峰位于593,613nm。当Eu^(3+)掺杂物质的量的浓度大于14%时,出现了浓度猝灭现象。在319nm紫外光激发下,YF_3:0.14Eu^(3+),0.08Gd^(3+)的发射光谱出现Eu^(3+)的5D0→7F1(593nm,橙光)、5D0→7F2(613nm,红光)跃迁发光峰,此时,Gd^(3+)的掺杂能增强Eu^(3+)的发光。通过色坐标分析可知,当激发波长为374nm时,YF_3:0.14Eu^(3+)的色坐标为(0.337 2,0.239 4),是很好的红色发光粉。对YF_3:xEu^(3+)和YF_3:0.14Eu^(3+),0.08Gd^(3+)的荧光衰减曲线的拟合证实,存在Gd^(3+)→Eu^(3+)的能量传递。

Effects of substitution of BaF_2 for GdF_3 on optical properties of dense oxyfluoride borogermanate scintillating glasses

Eu3＋-activated B2O3-GeO2-37Gd2O3-3Eu2O3-（15-x）GdF3-xBaF2 （0≤x≤15） scintillating glasses with the density of 6.1-6.3 g/cm3 were synthesized by a melt-quenching method. The substitution of BaF2 for expensive GdF3 in oxyfluoride borogermanate glasses slightly decreased the glass density within 3.0%. Their optical properties were characterized by transmittance, photolumines- cence （excitation and emission）, and X-ray excited luminescence （XEL） spectra in detail. The emission intensity of Eu3＋ ions increased with the elevated x values. The Eu-O covalancey nature and the local environment of Eu3＋ ions were evaluated by Judd-Ofelt results. It was found that the covalency property of Eu-O bond increased with increasing x values.

Influence of CeO_2 on scintillating properties of Tb^(3+)-doped silicate glasses

A series of Tb3+-,Ce3+-doped,and Tb3+/Ce3+-codoped silicate glasses were synthesized by melt-quenching technique.Some properties of the investigated glasses were characterized by X-ray photoelectron spectroscopy(XPS),photoluminescence(PL),X-ray excited luminescence(XEL) and thermoluminescence(TL) spectra.The result of XPS revealed that both Ce3+ and Ce4+ ions coexisted in these silicate glasses,and energy transfer from Ce3+ to Tb3+ ions was observed under UV excitation.However,under X-ray excitation the XEL...

Novel phosphors of Eu^(3+), Tb^(3+) or Tm^(3+) activated LaBGeO_5

Rare earth borogermanates as a group of stable compounds provided various potential properties important for modern sciences. Among the properties of interests, luminescence was manifested due to the variability of rare earth elements and the compounds constituted an important group of potential candidate. In this work, novel phosphors of Eu3＋, Tb3＋ or Tm3＋ doped LaBGeO5 with the stillwellite type structure were synthesized by the solid state reaction method. Their X-ray and UV excitation luminescent properties showed that LaBGeO5 was an excellent host lattice for the luminescence of Eu3＋, Tb3＋ and Tm3＋. The LaBGeO5：Eu3＋, LaBGeO5：Tb3＋ and LaBGeO5：Tm3＋ presented bright red, green and blue emission light for both UV and X-ray excitation.