钨酸铅(PbWO_4)晶体的发光均匀性研究

通过对下降法生长的全尺寸钨酸铅（ＰｂＷＯ４）晶体沿长轴方向不同点的透过率和光产额的测量、分段晶体的透过率和光产额的测量,研究了钨酸铅晶体的发光均匀性及其影响因素．结果表明：钨酸铅晶体发光均匀性主要由生长后期的钨酸铅晶体质量所决定,采用晶种为大头的加工取向有利于提高钨酸铅晶体的发光均匀性．     

193 nm激光下不同含量Y杂质CaF2晶体辐照损伤研究(英文)

氟化钙晶体的抗辐照性能是其在深紫外光刻应用中的关键性能之一,目前氟化钙晶体在193nm激光辐照下的损伤过程尚不清楚。本文报道了193 nm激光辐照下氟化钙晶体的损伤行为及影响损伤的关键缺陷因素。通过193nm激光辐照试验,发现晶体损伤主要表现为晶体内部产生的辐照诱导色心与表面产生的辐照诱导损伤坑。通过紫外–可见分光光度计对辐照诱导色心分析,并将不同色心吸收系数与Y杂质含量进行线性拟合。结果表明:Y离子具有与F心结构波函数发生重叠的低位轨道,两者发生轨道杂化易形成色心稳定结构;线性拟合结果表明Y离子含量与氟化钙晶体本征色心之间存在线性关系,说明Y元素是影响色心形成的关键杂质离子。实验表征了辐照诱导损伤坑的元素分布和结构缺陷。EDS结果表明损伤坑处伴随着钙元素含量上升和氟元素含量下降,证实H心扩散、F心聚集导致了辐照损伤;EBSD结果表明表面辐照损伤优先在位错处产生。因此,降低杂质含量及位错密度是提高氟化钙晶体在193 nm激光下抗辐照损伤性能的重要途径。     

Y3+:PbWO4晶体低剂量辐照行为研究

三价稀土离子（La^3 ,Lu^3 ,和Y^3 等）掺杂显著地提高了钨酸铅晶体的辐照硬度,但是部分Y^3 掺杂钨酸铅晶体表现出特殊的低剂量辐照行为,即光产额辐照后升高,并且辐照硬度对退火温度较敏感,研究研究挑选了存在这一现象的Y^3 :PbWO4晶体,测试冰同温度的退火处理对晶体透过率,光产额和辐照硬度的关系,发现,辐照后光产额升高的现象同时存在于晶体的晶种端,而不是只集中在晶体顶端,并且和辐照前后晶体在400－500nm波段附近的透过率变化有关;生长态Y^3 :PbWO4晶体中导致430nm吸收带的色心的稳定性很低,低剂量辐照对该色心有“漂白”作用,辐照剂量率加大则晶体表现出光产额的降低,分段晶体的系列退火实验解释了辐照硬度对退火温度较为敏感这一现象,为进一步深入研究提供了实验基础。     

Y3+:PbWO4晶体低剂量辐照行为研究

三价稀土离子(Ｌａ^３＋、Ｌｕ^３＋和Ｙ^３＋等)掺杂显著地提高了钨酸铅晶体的辐照硬度,但是部分Ｙ^３＋掺杂钨酸铅晶体表现出特殊的低剂量辐照行为,即光产额辐照后升高,并且辐照硬度对退火温度较敏感 本研究挑选了存在这一现象的Ｙ^３＋:ＰｂＷＯ_４晶体,测试不同温度的退火处理对晶体透过率、光产额和辐照硬度的关系,发现:辐照后光产额升高的现象同时存在于晶体的晶种端,而不是只集中在晶体顶端,并且和辐照前后晶体在４００~５００ｕｍ波段附近的透过率变化有关;生长态Ｙ^３＋:ＰＷＯ晶体中导致４３０ｕｍ吸收带的色心的稳定性很低,低剂量辐照对该色心有“漂白”作用,辐照剂量率加大则晶体表现出光产额的降低;分段晶体的系列退火实验解释了辐照硬度对退火温度较为敏感这一现象,为进一步深入研究提供了实验基础．     

钨酸铅(PbWO4)晶体的发光均匀性研究

通过对下降法生长的全尺寸钨酸铅（PbWO4）晶体沿长轴方向不同点的透过率和光产额的测量、分段晶体的透过率和光产额的测量,研究了钨酸铅晶体的发光均匀性及其影响因素。结果表明：钨酸铅晶体发光均匀性主要由生长后期的钨酸铅晶体质量所决定,采用晶种为大头的加工取向有利于提高钨酸铅晶体的发光均匀性。     

钨酸铅(PbWO_4)晶体的研究进展

钨酸铅(PWO)晶体由于自身特点:高密度(8.28g/cm~3)、短辐射长度(0.87cm)和Moliere半径(2.12cm)、快的闪烁衰减时间((?)<50ns)以及较强的抗辐照损伤能力,已经成为了最具发展潜力的闪烁晶体之一,作为一种良好的闪烁晶体,PWO晶体在高能物理、核医学等领域有着广泛的应用。主要综述了PWO晶体的结构、发光机制、自身缺陷、晶体生长的研究现状,着重阐述了生长工艺改善和离子掺杂改性对钨酸铅晶体性能的影响,分析了PWO晶体的发展前景。     

钨酸铅（PbWO4）闪烁晶体研究进展

钨酸铅（ＰｂＷＯ４）闪烁晶体是拟使用于西欧大型强子对撞机（ＬＨＣ）中精密电磁量能器量有希望的候选者，本文概要介绍了近年来国际上对于钨酸铅晶体的研究进展。包括它的闪烁性能、发光机制、辐照硬度和杂质效应等。本文最后列出了欧洲核子研究中心（ＣＥＲＮ）的ＣＣＣ组最近对７５根大尺寸ＰＷＯ晶体综合测试的统计结果。这有助于建立批量生产ＰＷＯ晶体的质量监控方法。     

Cherenkov辐射材料的研究历史和现状

追溯了Cherenkov效应和Cherenkov辐射材料的研究历史,重点介绍了曾成功用作Cherenkov辐射探测器的铅玻璃和立方氟化铅晶体的性能特点,并对目前正在研究的钨酸铋钠和重掺杂钨酸铅晶体进行了评述和讨论.     

钨酸铅（PbW04）晶体的研究进展

钨酸铅（PWO）晶体由于其自身特点：高密度（8．28g／cm^3）、短辐射长度（0．87cm）和Moliere半径（2．12cm）、快的闪烁衰减时间（t〈50ns）以及较强的抗辐照损伤能力，已经成为了最具发展潜力的闪烁晶体之一，作为一种良好的闪烁晶体，PWO晶体在高能物理、核医学等领域有着广泛的应用。主要综述了PWO晶...     

Mo^6＋，Gd^3＋，PbF2组合掺杂对钨酸铅发光的改善和光谱分析

坩埚下降法生长了（Mo^6＋、PbF2），（Mo^6＋、Gd^3＋），（PbF2，Gd^3＋）组合掺杂，及PbF2单掺杂钨酸铅晶体，对样品进行了吸收光谱、光产额、x射线和紫外激发发光光谱等测试和表征，讨论了掺杂对钨酸铅发光的增强效果。掺杂钨酸铅总发光额都得到了增强；在门宽100ns内晶体的光产额都有提高，但在测试门宽在200ns内，（Gd^3＋、PbF2）掺杂样品光产额有所下降。x射线激发发光显示，PbWO4：（Mo^6＋、Gd^3＋）的蓝发光和绿发光分量都有提高；PbWO4：（Mo^6＋、PbF2）蓝发光受到拟制，提高了绿发光成分，晶体光学吸收边明显红移。PbWO4：（Gd^3＋、PbF2）蓝发光得到增强，绿发光得到一定的拟制。光致发光光谱分析表明，Gd^3＋掺杂对PbWO4基质发光有敏化作用。实验证实，F在PbWO4生长中非常不稳定，显示很差的掺杂均匀性。     

Luminescent properties of CdSe single crystals doped with antimony or bismuth

CdSe single crystals were doped with Bi and Sb from Sb₂Se₃ and Bi₂Se₃ vapors. The introduction of Sb and Bi was found to produce new luminescence centers. Both bismuth and antimony generate deep levels in the band gap of CdSe. The maxima in the photoconductivity spectra of Sb and Bi-doped CdSe are redshifted. Both doped and undoped CdSe crystals are shown to be photosensitive     

溶胶-凝胶法和微波辐射法制备Mg2SiO4Mn2＋红色荧光粉制备及发光性质的研究

采用溶胶-凝胶法和微波辐射法制备了Mg2SiO4Mn2＋红色发光材料。研究了以Mg2SiO4为基质,在掺杂Mn2＋的情况下,微波合成时间和Mn2＋的掺杂浓度对发光性能的影响。选择最佳微波合成时间和Mn2＋的掺杂浓度,制备了在410nm激发下,发光中心位于690nm的红色发光材料。     

Prompt and delayed recombination mechanisms in Lu4Hf3O12 nanophosphors

We study lutetium hafnate, Lu₄Hf₃O₁₂, prepared by acetate and citrate combustion in the form of nanometric powders. Optical properties including X-ray excited luminescence, steady-state and time resolved photoluminescence as well as thermally stimulated luminescence are investigated for undoped as well as Eu³⁺ and Tb³⁺ doped samples. We identify recombination centers in the host matrix and we tentatively associate the principal emission with a radiative transition of the F⁺ center. We also demonstrate that athermal tunneling of charge carriers between traps and recombination centers is the predominant mechanism of delayed radiative recombination following irradiation by ionizing radiation.     

Fabrication of luminescent silver doped PbS nanowires in polymer

We report here fabrication of silver (0 to 1.76 mol%) doped PbS nanowires (radius r approximately 1.75 nm) in polymer by a simple wet chemical process. An X-ray photoelectron spectroscopy study clearly confirms the possibility of silver (Ag) doping in PbS nanowires. Both absorption and photoluminescence spectra reveal very strong quantum confinement effect in PbS nanowires as expected for a r/Bohr radius ratio approximately 0.0972 nm. Visible excitonic emission is observed at room temperature in the photoluminescence spectra of undoped and silver doped PbS nanowires in polymer. The excitonic emission is appreciably blue-shifted when doped by silver (1.76 mol%) indicating strong modification of the electronic states by magnetic silver ions. While Ag2+ centers at the substitutional lattice site show an emission band around 525 nm, Ag0 at the interstitial site act as nonradiative recombination centers. Effect of silver doping on the luminescence intensity is also discussed.     

Effect of annealing on luminescence properties of the undoped and rare earth doped lead tungstate crystals

The paper reports results of comparable spectral investigation of thermal treatment effects on luminescent properties of the undoped and rare earth doped lead tungstate crystals. Annealing at 950 °C leads to pronounced changes in the emission and excitation spectra of the undoped PbWO₄ crystals whereas observed effect of annealing on the spectra of the RE-doped crystals is weak. Decrease of the relative contribution of blue luminescence emission band and changes at the sharp long wavelength edge of the excitation spectra are the most distinctive results of annealing on the spectra of the undoped crystals. Observed changes can be explained by manifestations of two exciton transitions in the corresponded spectra. Two types of exciton luminescence bands arise from the lattice regions with different defects of the crystal structure (e.g., with vacancies in the anion or cation sublattices). Adding of the RE ions decreases content of vacancies in the PWO crystal lattice and improves in such a way thermal stability of spectral properties of the blue luminescence of these crystals.     

The poly(ethylene terephthalate)/polyaniline composite: AFM, DRS and EPR investigations of some doping effects

A composite based on PET as a matrix and a thin layer of PANI produced by chemical polymerisation of aniline in the surface layer of the PET is investigated by means of four probe conductivity method, standard and conducting AFM, DRS and EPR techniques. Conducting AFM shows that PANI forms conducting clusters. Standard AFM topographical images prove that the undoped form of the composite has a flat surface, whereas the doped one exhibits mountainous features. DRS spectra revealed that the transition from the undoped form to the doped one is accompanied with an increase of the high frequency peak associated to conductivity of the clusters leading to the appearance of two low frequency relaxation processes connected with interfacial polarization phenomena. It is found that the relaxation behaviors of the composite doped by HClO₄ and HCl acids are similar. The EPR spectra obtained in both doped and undoped forms of the composite are induced by two kinds of paramagnetic centres (PC). Irrespective to the dopant, anomalous thermal behaviors of the PC spin relaxation times and susceptibilities are evidenced above 180 K. These effects are connected with changes in the electronic transport properties.     

Luminescence and photoconductivity of alkali-metal-doped cadmium sulfide films

Data are presented on the luminescence and photosensitivity of cadmium sulfide films doped with an alkali metal (Na or K) in the presence of chlorine. The doping is shown to increase the luminescence quantum yield by more than one order of magnitude in comparison with undoped CdS films. The doped films are resistant to high-intensity UV radiation, which usually initiates photochemical reactions.     

Structural and optoelectronic characterization of prepared and Sb doped ZnO nanoparticles

This paper briefly reports the structural and optoelectronics properties of prepared pure and Sb doped ZnO nanoparticles. Doping with suitable elements offers an efficient method to control and enhance the optical properties of ZnO nanoparticles, which is essential for various optoelectronics applications. Sb doped ZnO nanoparticles have significant concern due to their unique and unusual electrical and optical properties. In the present work, we report the synthesis of Sb doped ZnO successfully with average particle size range from 26 to 29 nm via direct precipitation method. The phase purity and crystallite size of synthesized ZnO and Sb doped nano-sized particles were characterized and examined via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The elemental analyses of undoped and doped ZnO nanoparticles were examined by using energy-dispersive X-ray spectroscopy (EDAX).We investigated and measured the optoelectronics properties of synthesized ZnO and Sb doped ZnO nanoparticles by employing photoluminescence and UV–Visible spectroscopy. The influence of Sb doping on photoluminescence (PL) spectra of ZnO nanoparticles, which consists of UV emission and broad visible emission band, is found to be strongly dependent upon the Sb concentration for all the Sb doped ZnO nanoparticles samples under investigation. The UV–Visible absorption study shows an increase in band gap energy as Sb is incorporated on the ZnO nanoparticles.     

Spectrally resolved luminescence of undoped and Dy3+ doped Na2SO4

Structural phase transitions influence the luminescence characteristics by modifying the spectra, sensitivity and luminescence efficiency in each phase. This has implications for dosimetric materials both for sensitivity and reproducibility. Previous work with dosemeter materials has not documented effects of different phases on thermoluminescence but Na2SO4 exists in several phases in the temperature range of interest for thermoluminescence dosimetry. Therefore spectrally resolved TL and radiothermoluminescence analyses of undoped and Dy3+ doped Na2SO4 have been performed. Dramatic differences between TL of slow cooled and quenched Na2SO4:Dy are explained in terms of the initial phase of the samples at room temperature. For undoped material the effect of phase conversions during heating shift the wavelengths of the emission bands. A model of Dy in small precipitate phases is considered.     

Photoluminescence characteristics of Ti2S3 nanoparticles embedded in sol–gel derived silica xerogel

Ti₂S₃ nanocrystallites embedded in sol–gel derived silica xerogel have been prepared. Their photoluminescence (PL) characteristics have been evaluated and compared with those of pure silica xerogel. UV–vis absorption spectra, transmission electron micrograph, excitation spectra and PL spectra of the doped and undoped samples have all been investigated. Two emission peaks have been observed from the doped samples, one at 440 nm (λ_ex=380 nm) while the other at 600 nm (λ_ex=550 nm). The latter has been assigned to the Ti₂S₃ nanocrystallites in the silica xerogel. Therefore, a novel luminescence property can be observed by introducing the semiconductor nanoparticles into the silica xerogel.