Tm3+和 Yb3+共掺杂PGETYA玻璃的直接敏化上转换发光

制备了一种稀土离子掺杂的PGETYA氟氧玻璃材料,它不仅具有较高的上转换发光效率,而且还避免了氟化物基质的缺点。其组分为58.52PbF₂-34.43GeO₂-3Al₂O₃ -0.05Tm₂O₃-4Yb₂O₃,以共掺杂Tm³⁺和Yb³⁺离子为上转换研究的对象。测量了该玻璃系统在980 nm LD激发下的上转换发光光谱,观察到很强的476 nm的蓝色荧光,它来源于Tm³⁺离子的¹G₄→³H₆跃迁。同时,还有两个较弱的红色荧光来源于Tm³⁺离子的¹G₄→³H₄和³F₃→³H₆跃迁。对上转换发光强度与泵浦电流关系曲线的拟合结果表明:此材料的蓝色上转换为三光子过程,红色上转换为双光子过程。     

交换纤维柱分离ICP-AES测定高纯氧化镱中La、Nd、Eu和Gd

以强酸型离子交换纤维柱分离富集高纯Yb₂O₃中La,Nd,Eu和Gd等痕量杂质元素,并用Optima 5300 DV ICP-AES测定分离富集后的这4种元素。供试纤维对Yb的动态吸附容量为134 mg·g-1,4.0 g纤维柱的分离条件为：pH 3.00的试液以1.0 mL·min-1流速上柱后,分离柱先以流速为1.5 mL·min-1的pH 3.00 HNO₃溶液80 mL预淋洗,再以同样流速pH 5.00的0.01 mol·L-1 EDTA铵溶液淋洗。结果表明：10 mg Yb与各为0.100 μg的La,Nd,Eu和Gd能达到基线分离;分离含100 mg Yb的试液后,在杂质富集液中Yb的残留浓度仅为0.017 1 μg·mL-1。 研究显示,当待测试液中Yb₂O₃的浓度小于100 μg·mL-1(如Yb 87.8 μg·mL-1)时,它对测定La,Nd,Eu和Gd等杂质元素的基体干扰可以忽略不计。富集倍数分别为La₂O₃ 3.68×105,Nd₂O₃ 4.20×105,Eu₂O₃ 3.82×105,Gd₂O₃ 4.01×105。方法检出限分别为La₂O₃ 0.005 0 pg·mL-1,Nd₂O₃ 0.014 pg·mL-1,Eu₂O₃ 0.001 8 pg·mL-1,Gd₂O₃ 0.008 2 pg·mL-1。本方法已用于99.99% Yb₂O₃样品中4种稀土杂质的测定,标准加入的平均回收率分别为La₂O₃ 94.2%,Nd₂O₃ 107%,Eu₂O₃ 97.8%,Gd₂O₃ 102%,RSD (%, n=5)分别为La₂O₃ 6.2,Nd₂O₃ 5.9,Eu₂O₃ 7.3,Gd₂O₃ 2.5,校正曲线不需进行Yb的基体匹配,分析周期为4 h。     

掺铋BaF2晶体的制备及其近红外发光研究

通过温度梯度法制备了Bi₂O₃:BaF₂以及BiF₃:BaF₂晶体.在Bi₂O₃:BaF₂晶体中观察到了发光峰位于961 nm,半高宽202 nm的超宽带红外发光.在BiF₃:BaF₂晶体中检测到Bi²⁺和Bi³⁺可见区的发光,但是没有观察到红外发光.通过γ射线辐照实现了BiF₃:BaF₂晶体的近红外发光, 发光峰位于1135 nm,半高宽192 nm.讨论了Bi₂O₃和BiF₃掺杂BaF₂晶体的红外发光的机理. 关键词： 近红外发光 铋 氟化钡晶体 γ辐照     

(Sr,Ca)4Si3O8Cl4基质中Eu2+的发光特性研究

采用高温固相法合成Sr4-xCaxSi3O8Cl4：Eu^2＋荧光材料,利用Van Uitert公式讨论Sr4-xCaxSi3O8Cl4：Eu^2＋中yEu^2＋的晶格环境和发光特性,确定晶体中有蓝色和黄绿色两种发光中心,并讨论了它们与光谱结构的对应关系。当0〈x〈0．5,Ca^2＋固溶入Sr4Si3O8Cl4基质晶格,Eu^2＋占据八配位Si^2＋格位,晶体主要产生蓝色中心的蓝绿色发射;当0．5〈x〈2,较大的Ca^2＋掺杂使晶胞参数变小,品格中的杂质束缚激子态的束缚增强,Eu^2＋处于杂质束缚激子中心所形成的激发态能量进一步降低,发射位于长波段方向并具有较大的Stokes位移,Sr4-xCaxSi3O8Cl4：yEu^2＋主要产生黄绿色中心的黄绿色发射光。     

长余辉发光粉Ba1-xCaxAl2O4:Eu2+, RE3+的发光特性及光谱分析

采用高温固相法制备了长余辉发光粉Ba1-xCaxAl2O4:Eu^2 ,RE^3 (RE^3 =Dy^3 ,Nd^3 ),测量了其发射光谱、激发光谱、余辉衰减光谱和热释光谱,分析了其发光特性。在紫外线的激发下样品的发射波长随着x的变化而变化,x从0到0．6的范围变化时,发射波长相应地从498nm减小到440nm,当x大于0．6以后,波长保持440nm不再变化。通过XRD光谱对其结构进行了分析,得出Ca离子在BaAl2O4基质中有极限溶解度x0=0．4,当x大于0．4时,基质结构中出现杂相。通过热释光谱,对基质中的陷阱情况进行了分析,解释了由于x值的不同而造成的余辉时间长短的差异。     

980nm激光激发下Er3+和Yb3+共掺杂氟氧玻璃的上转换发光

制备了一种新型的上转换发光材料,它不仅具有较高的上转换发光效率,而且还避免了氟化物基质的缺点。其组分为58.52%PbF₂-34.43% GeO₂-3% Al₂O₃-0.05% Er₂O₃-4%Yb₂O₃,其中GeO₂为玻璃形成体氧化物,PbF₂和Al₂O₃为调整剂,以共掺杂Er³⁺和Yb³⁺离子为上转换研究的对象。测量了该玻璃系统在980nm半导体激光器激发下的上转换发光光谱,观察到很强的658nm的红光和548,526nm的绿光,而且红光的发射强度远远强于绿光。通过对上转换发光强度与激发强度关系曲线的拟合,表明此材料的绿光发射和红光发射都为双光子过程。研究了激发光的工作电流与上转换荧光强度的关系,讨论了其上转换发光特性。     

一种制备银－氧化铝覆盖的滤纸基片的新方法

一种制备银－氧化铝覆盖的滤纸基片的新方法左晨，周群，王焕茹，郁鉴源（清华大学化学系北京１０００８４）ＡＭｅｔｈｏｄｆｏｒＰｒｅｐａｒｉｎｇＳｕｒｆａｃｅ－ＥｎｈａｎｃｅｄＲａｍａｎＳｃａｔｔｅｒｉｎｇＳｉｌｖｅｒ－Ａｌｕｍｉｎａ－ｐａｐｅｒＳｕｂｓｔ...     

Low thermal expansion and broad band photoluminescence of Zr0.1Al1.9Mo2.9V0.1O12

A new material of Zr0.1Al1.9Mo2.9V0.1O12 is synthesized by the traditional solid state synthesis method.The phase transition,coefficient of thermal expansion,and luminescence properties of Zr0.1Al1.9Mo2.9V0.1O12 are explored with Raman spectrometer,dilatometer,and x-ray diffraction(XRD)diffractometer.The results show that the Zr0.1Al1.9Mo2.9V0.1O12 possesses the strong broad-band luminescence characteristics almost in the whole visible region.The sample is crystallized in a monoclinic structure group of P21/a(No.14)crystallized at room temperature(RT).The crystal is changed from monoclinic to orthorhombic structure when the temperature increases to 463 K.The material has very low thermal expansion performance in a wide temperature range.Its excellent low thermal expansion and strong pale green light properties in a wide temperature range suggest its potential applications in light-emitting diode(LED)and other optoelectronic devices.     

Er3+/Yb3+/Tm3+共掺杂氟化物中红色上转换发光研究

氧化铒的质量增加到原来的10倍左右时发现两种配方的发光性质有明显不同。根据情况作研究了Er^3 ／Tm^3,Er^3 ／Er^3-和Er^3 ／Yb^3 /Tm^3 发光系统在980nm抽运下的荧光光谱和上转换发光的性质,以及在声子能量较低的氟化物中,3个发光系统建立的优先性和Er^3 离子浓度的关系。根据实验发现当Er^3 离子浓度由小逐渐变大时,绿光和红光的强弱比例也有明显的变化。其中作认为起决定性作用的是Er^3 离子浓度。因为在均匀体系中每个稀土离子的和另一个稀土离子的结合形成发光系统的机会是平等的,组成发光系统的稀土离子间的距离变化,即其中一种起决定作用的离子浓度变化时,那么它所组成的发光系统也就相应发生变化(稀土离子的优先结合性也会在此得到体现),从而发出的主色的光也就跟着变化。     

酶催化动力学光度法测定抗坏血酸

基于抗坏血酸对血红蛋白模拟酶催化体系的抑制作用,建立酶催化动力学光度法测定抗坏血酸的新方法。研究了体系的最佳条件及动力学行为,测定的线性范围为2.0×10-7—5.9×10-5mol/L,方法检出限为7.0×10-8mol/L。对6.0×10-6mol/L的抗坏血酸进行11次平行测定相对标准偏差为2.5%。此方法可用于药剂和蔬菜中抗坏血酸含量的测定。     

纳米棒状长余辉材料BaAl_2O_4:Eu~(2+),Dy~(3+)的制备与发光性能

利用硝酸铝、硝酸钡、尿素为原料,以一定比例H_2O/正丁醇及H_2O/正丁醇/SBS的混合液作传递压力的介质,进行反应,然后将得到的前驱体在还原气氛下高温煅烧,得到亮度高,余辉时间长的BaAl_2O_4:Eu~(2+),Dy~(3+)纳米棒状长余辉发光材料。TEM和SEM测试表明高温煅烧后得到的BaAl_2O_4:Eu~(2+),Dy~(3+)为棒状结构,其激发光谱和发射光谱均为宽带,主发射峰分别为498 nm,是典型的Eu~(2+)5d→4f跃迁。该方法的特点在于:采用水热法合成的BaAl_2O_4:Eu~(2+),Dy~(3+)长余辉发光材料一般需经过高温煅烧,容易结块,而在合成制得的产品经1 300℃高温煅烧后仍呈现分散性良好的棒状结构,不需球磨,且发光性能良好,可直接应用。同时将2种不同的实验条件进行比较,发现在不使用表面活性剂的条件下依然可得到分散性良好的棒状BaAl_2O_4:Eu~(2+),Dy~(3+)长余辉发光材料。该制备方法有望在其他铝酸盐和硅酸盐系长余辉发光材料的制备中得到应用。     

基质组成对Eu,Dy共掺杂铝酸锶发光性能的影响

研究了基质组成对xSrO·yAl₂O₃:Eu²⁺,Dy³⁺体系长余辉发光性能的影响,并对其影响机理进行了探讨.XRD分析结果和长余辉发光性能表明,改变Al₂O₃/SrO比率可以获得长余辉发光性能较好的三种基质相:SrAl₂O₄:Eu²⁺,Dy³⁺、Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺和SrAl₄O₇:Eu²⁺,Dy³⁺.激发与发射光谱性能分析和余辉衰减特性分析结果表明,随着基质中Sr/Al比例的减小,激发光谱向短波方向延伸,发射峰蓝移,初始余辉亮度越高,余辉持续时间越长.热释光谱分析表明,贫锶相晶格中的陷阱深度与密度较大,因而显示出较好的长余辉发光性能.     

On the response of semitransparent nanoparticulated films of LuPO<Subscript>4</Subscript>:Eu in poly-energetic X-ray imaging applications

In the present work, we demonstrate the fabrication technique of highly translucent layers of nanoparticulated (~50 nm) LuPO₄:Eu phosphor, present their basic luminescent properties and give results of their performance in a planar imaging system coupled to a CMOS photodetector. For comparison, the imaging performance of an opaque Gd₂O₂S:Eu phosphor screen prepared by sedimentation is also shown. The X-ray detection parameters as well as the luminescence efficiency of the investigated films were discussed. Results show that the in-line transmittance at ~600–700 nm, in the range of the phosphor luminescence, varies with respect to the thickness of the films from 40 to 50 % for a film of 67 μm thick to 4–12 % when the thickness increases to 460 μm. Yet, X-ray detection parameters get enhanced as the thickness of the films increases. Those results affect the luminescence efficiency curves of the films under poly-energetic X-ray radiation of various tube energies. The normalized noise power spectrum values were found similar for LuPO₄:Eu films and a phosphor screen made using commercial Gd₂O₂S:Eu powder. The detective quantum efficiency of our films is clearly lower compared to the Gd₂O₂S:Eu screen from 2 to 10 cycles mm^?1 frequency range while the modulation transfer function is lower from 0 to 5.5 cycles mm^?1 frequency range. The acquired data allow to predict that high-temperature sintering of our films under pressure may help to improve their imaging quality, since such a processing should increase the luminescence efficiency without significant growth of the grains and thus without sacrificing their translucent character.     

Review of gallium oxide based field-effect transistors and Schottky barrier diodes

Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.     

Local Structure Analysis of Lead Zinc Niobate-Barium Titanate Ceramic by X-Ray Absorption Spectroscopy and Density Functional Calculation

The local structure of an alternative Pb(Zn_(1/3)Nb_(2/3))O3-based perovskite ceramic is investigated. The 0.07 BaTiO_3-0.93 Pb(Zn_(1/3)Nb_(2/3))O_3 ceramic is synthesized using a combination of Zn_3 Nb_2 O_8 B-site precursor and BaTiO_3 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2+ is found to replace_Pb)~(2+) in A-site with Zn~(2+) occupying B-site in Pb(2 n_(1/3)Nb_(2/3))O_3, while in the neighboring structure, Ti~(4+)replaces Nb~(5+) in B-site with Pb~(2+) occupying A-site. With the substitution of BaTiO_3 in Pb(Zn_(1/3)Nb_(2/3))O_3, the bond length between Zn2+ and Pb~(2+) is longer than that of the typical perovskite phase of Pb(Zn_(1/3)Nb_(2/3))O_3.This indicates the key role of BaTiO_3 in decreasing the steric hindrance of Pb~(2+) lone pair, and the mutual interactions between Pb~(2+) lone pair and Zn2+ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO_3 in stabilizing the perovskite phase in PbZn_(1/3)Nb_(2/3)O_3-based materials,which in turn will lead to an improved preparation technique for desired electrical properties.     

Molten-salt synthesis and composition-dependent luminescent properties of barium tungsto-molybdate-based solid solution phosphors

Pr~(3+)-activated barium tungsto-molybdate solid solution phosphor Ba(Mo_(1-z)W_z)O_4:Pr~(3+)is successfully fabricated via a facile molten-salt approach. The as-synthesized microcrystal is of truncated octahedron and exhibits deep-red-emitting upon blue light excitation. Powder x-ray diffraction and Raman spectroscopy techniques are utilized to investigate the formation of solid solution phosphor. The luminescence behaviors depend on the resulting composition of the microcrystals with fixed Pr~(3+)-doping concentration, while the host lattices remain in a scheelite structure. The forming solid solution via the substitution of [WO_4] for [MoO_4] can significantly enhance its luminescence, which may be due to the fact that Ba(Mo_(1-z)W_z)O_4:Pr~(3+)owns well-defined facets and uniform morphologies. Owing to its properties of high phase purity,well-defined facets, highly uniform morphologies, exceptional chemical and thermal stabilities, and stronger emission intensity, the resulting solid solution phosphor is expected to find potential applications in phosphor-converted white lightemitting diodes(LEDs).     

非晶La_(1-x)Nd_xP_5O_(14)的拉曼散射研究

本文利用拉曼散射对非晶 La_(1-X)Nd_XP_5O_(14)及其晶化过程进行了研究。拉曼散射表明在非晶La_(1-X)Nd_XP_5O_(14)中仍保留着晶态 La_(1-X)Nd_XP_5O_(14)中具有的 PO_4~(3-)四面体结构单元。非晶La_(1-X)Nd_XP_5O_4在不同温度下晶化,其拉曼谱线的频率不同,这一现象可用应力模型给予解释。     

Er3+/Tm3+共掺碲酸盐玻璃光谱特性及能量传递

采用高温熔融法制备了两系列不同掺杂比的Er³⁺/Tm³⁺共掺的碲酸盐玻璃,测试了样品的吸收光谱和在980 nm LD激发下的发光光谱、上转换发光光谱及发光寿命。讨论了Er³⁺与Tm³⁺掺杂浓度对样品光谱性质的影响,Tm³⁺离子的掺入会减弱Er³⁺的1.53 μm发光强度,但通过共振能量传递可以获得Tm³⁺的1.8 μm发光,并随着Tm³⁺离子浓度的增加而增强。同时表明Tm³⁺离子的增加会减弱Er³⁺离子在528 nm和545 nm附近的上转换绿光强度,而上转换红光出现了先增强后减弱的现象。研究了Er³⁺/Tm³⁺共掺杂碲酸盐玻璃的能量传递机制与传递效率,分析了Tm³⁺/Er³⁺离子掺杂浓度比对上转换发光的影响。     

H_2O_2诱导的植物叶片光子辐射的变化及意义

为了研究植物叶片光子辐射与氧化胁迫的关系,将鹅掌木叶片用不同浓度的H_2O_2进行了处理,从而形成氧化胁迫.实验结果表明,随着H_2O_2处理时间的延长,浓度为7.5%、15%和30% 的H_2O_2处理均使鹅掌木叶片光子辐射中的自发发光较未受处理的对照有明显增长,各处理组叶片的延迟发光动力学曲线均呈现双曲性弛豫.通过建立延迟发光非线性动力学方程和数学模拟,得到了延迟发光的特征参量初始光子数I_0、相干时间τ和衰减参量β,发现随着H_2O_2处理时间的延长,各处理组叶片的I_0都呈现先下降,后回升,再下降的波动趋势;而浓度为7.5%和15%的两个处理组的叶片τ值和β值呈现波动变化,浓度为30%的处理组的叶片τ和β呈现单调下降的趋势.推测H_2O_2胁迫下叶片光子辐射中自发发光的变化反映了叶片活性氧含量的变化;叶片延迟发光中I_0的变化反映了细胞总体代谢的变化,延迟发光中的τ值和β值的变化反映了叶片细胞对H_2O_2胁迫的适应和损伤过程.     

Preparation and Time-Resolved Luminescence Bioassay Application of Multicolor Luminescent Lanthanide Nanoparticles

Because highly luminescent lanthanide compounds are limited to Eu³⁺ and Tb³⁺ compounds with red (Eu, ~615 nm) and green (Tb, ~545 nm) emission colors, the development and application of time-resolved luminescence bioassay technique using lanthanide-based multicolor luminescent biolabels have rarely been investigated. In this work, a series of lanthanide complexes covalently bound silica nanoparticles with an excitation maximum wavelength at 335 nm and red, orange, yellow and green emission colors has been prepared by co-binding different molar ratios of luminescent Eu³⁺–Tb³⁺ complexes with a ligand N,N,N¹,N¹-(4′-phenyl-2,2′:6′,2′′-terpyridine-6,6′′-diyl)bis(methylenenitrilo) tetrakis (acetic acid) inside the silica nanoparticles. The nanoparticles characterized by transmission electron microscopy and luminescence spectroscopy methods were used for streptavidin labeling, and time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) as well as time-resolved luminescence imaging detection of an environmental pathogen, Giardia lamblia. The results demonstrated the utility of the new multicolor luminescent lanthanide nanoparticles for time-resolved luminescence bioassays.