Photoluminescence spectra of thenardite Na2SO4 activated with rare-earth ions, Ce, Sm, Tb, Dy and Tm

Five Na₂SO₄:RE³⁺ phosphors activated with rare-earth (RE) ions (RE³⁺=Ce³⁺, Sm³⁺, Tb³⁺, Dy³⁺ and Tm³⁺) were synthesized by heating natural thenardite Na₂SO₄ from Ai-Ding Salt Lake, Xinjiang, China with small amounts of rare-earth fluorides, CeF₃, SmF₃, TbF₃, DyF₃ and TmF₃, at 920 °C in air. The photoluminescence (PL) and optical excitation spectra of the obtained phosphors were measured at 300 and 10 K. In the PL spectrum of Na₂SO₄:Ce³⁺ at 300 K, two overlapping bands with peaks at 335 and 356 nm due to Ce³⁺ were first observed. Narrow bands observed in PL and excitation spectra of Na₂SO₄:RE³⁺ (RE³⁺=Sm³⁺, Tb³⁺, Dy³⁺ and Tm³⁺) phosphors were well identified with the electronic transitions within the 4fⁿ (n=5, 8, 9 and 12) configurations of RE³⁺. The existence of excitation bands with high luminescence efficiency at wavelengths shorter than 230 nm is characteristic of Na₂SO₄:RE³⁺ (RE³⁺=Sm³⁺, Tb³⁺, Dy³⁺ and Tm³⁺) phosphors. The obtained results suggest that these phosphors are unfavorable as the phosphor for usual fluorescence tubes, i.e., mercury discharge tubes, but may be favorable as the phosphor for UV-LED fluorescent tubes and as cathodoluminescence, X-ray luminescence and thermoluminescence phosphors.     

Dy3+激活无水芒硝在真空紫外光激发下的发光性质

在空气中900℃温度下,将纯天然无水芒硝( Na2 SO4)和DyF3的混合粉末加热25 min,制备了Na2SO4:Dy3+新型发光材料.通过同步辐射研究了NaSO4:Dy3+的发光性质.并测量了在室温中真空紫外-紫外光下的发射和激发光谱.根据发射光谱得到了不同Dy3+掺杂浓度和不同激发下发光的黄蓝比(Y/B)是不同的.通过监测黄色发光得到的激发光谱,分别由Dy3+,4f9→4f85d跃迁(172 nm)、O2--Tm3+之间的电荷转移带(165 nm)引起的强激发谱和基质吸收(138,245 nm)、对应Dy3+,6 H15/2→4 D7/2,6H15/2→6 P3/2,6 H15/2→6P7/2跃迁(299,325,351nm)引起的弱激发谱组成.     

Photoluminescence properties of thenardite activated with Eu

Na₂SO₄:Eu phosphors were prepared by heating pure natural thenardite with EuF₃ at 900 °C for 20 min in air. The photoluminescence (PL) and excitation spectra of as-prepared and γ-ray-irradiated phosphors were observed at 300 K. The PL spectrum under 394 nm excitation consisted of strong narrow bands with peaks at 579, 592, 616, 652, 697 and 741 nm, assigned to the ⁵D₀→⁷F_J (J=0, 1, 2, …, 5) transitions, respectively, within Eu³⁺. The PL spectrum under 340 nm excitation consisted of a broad Eu²⁺ band with a peak at 435 nm. The excitation spectrum obtained by monitoring the violet luminescence consisted of a weak band with a peak at approximately 261 nm and a broad Eu²⁺ band with a peak at approximately 338 nm. The relative efficiency of the violet luminescence of the γ-ray-irradiated phosphor at the exposure of 46 kGy increased up to 3.0 times that of the unirradiated phosphor. The enhancement of violet luminescence by γ-ray irradiation was ascribed to the conversion of Eu³⁺ to Eu²⁺ in Na₂SO₄.     

火电厂燃煤和粉煤灰及炉渣中天然放射性水平分析

本文采用低本底γ能谱仪对乌鲁木齐市华电和国电两个电厂的燃煤、粉煤灰和炉渣中的天然放射性核素含量进行了测量.测量结果:226Ra、232Th、40K含量的平均值,煤中分别为5.54、3.51、69.15Bq/Kg,粉煤灰中分别为26.99、15.89、122.69Bq/Kg,炉渣样中分别为28.79、15.98、116.72Bq/Kg.并依据国家标准对粉煤灰进行分类,结果表明,粉煤灰的使用不受限制.     

基于PGNAA法检测输油管道油垢厚度的初步实验研究

为改进石油输送过程中的油垢检测方法,应用PGNAA(瞬发γ射线中子活化分析)法对管道同一横截面处不同探测角度时不同石蜡(模拟油垢)厚度进行γ光子计数,研究发现γ光子计数响应与探测角度有很大关系.探测角度为135°时线性相关系数的平方和测量精度都是最佳,达到0.9986和0.906mm.本工作对PGNAA法检测油垢厚度选...     

Dy~(3+),Sm~(3+)共掺杂Ca_2A1[AlSiO_7]荧光粉的发光性质研究

采用高温固相反应法合成了一系列Dy~(3+)、Sm~(3+)单掺杂和共掺杂铝方柱石发光材料,详细地研究了Dy~(3+)、Sm~(3+)掺杂对铝方柱石的结构和发光性质的影响。XRD结果表明Dy~(3+)、Sm~(3+)离子单掺杂和共掺杂样品均形成了单相的铝方柱石结构化合物,并没有改变基质的晶体结构。发光光谱表明,通过调节Dy~(3+)、Sm~(3+)离子的掺杂比例,发光颜色可实现从黄色到黄白色的可控调节。此外,发射和激发光谱表明,Dy~(3+)与Sm~(3+)离子之间存在有效的光谱重叠,暗示着Dy~(3+)→Sm~(3+)的能量传递。荧光寿命衰减结果进一步证实Dy~(3+)与Sm~(3+)离子之间是一种无辐射共振能量传递方式。     

Ce激活氯化钠在真空紫外光激发下的发光性质

采用水热蒸发法制备了NaCl∶Ce3+荧光粉,并通过X射线衍射(XRD)研究了材料的晶体结构。测量并分析材料在室温下的真空紫外激发光谱及相应的发射光谱。结果表明309和324nm的发射峰,对应于Ce3+离子的5d→4f(2 F5/2,2 F7/2)跃迁;激发谱显示6个峰,峰位分别为148,190,205,216,232和247nm。148nm的激发峰是基质吸收引起的;190,205,216,232和247nm是Ce3+的4f→5d跃迁引起的。     

检测输油管道实际油垢样品的实验研究

在石蜡实验基础上,本工作运用γ射线散射法检测油垢样品进行对比实验研究,并在进一步的实验研究中探讨康普顿散射光子数与油垢样品厚度之间的线性关系．发现放射源与油垢样品之间的距离与提高线性度有很大关系．本实验测得最佳线性相关系数平方值为0．9871,测量精度为0．671mm．     

用γ射线Compton散射法来测定管道内油垢厚度

论文中讨论了散射截面与散射角和能量的关系．采用Compton散射总截面,推导出并分析了近水平入射小角度散射法的相应函数与靶介质厚度关系公式．数值拟合结果显示相应函数与油垢厚度之间存在立方性关系．     

非离子型微乳液存在下5-Br-PADAP光度法测定微量Co(Ⅱ)的研究

研究了在含水量 90 %的非离子型微乳液——乳化剂 op/正丁醇 /正庚烷 /水中 ,在室温下用 5- Br- PADAP与 Co( )的显色反应进行 ,分光光度法测定钴 ,配合物最大吸收波长在 588nm,摩尔吸光系数达 1 .1 3*1 0 5 L· mol-1· cm-1 ,与相同含水量的乳化剂 OP胶束体系相比 ,本法测定的灵敏度明显提高 .Co含量 0～ 30μg/ 2 5ml范围符合比耳定律