Eu3+离子在微晶玻璃研究中的探针作用

制备出单掺Eu³⁺离子的氟氧化物玻璃陶瓷系列样品，利用Eu³⁺离子作为荧光探针，通过热处理前后Eu³⁺离子发射光谱中电偶极子跃迁与磁偶极子跃迁强度比值的变化表征在玻璃材料中微晶是否形成，分析了Eu³⁺离子荧光发射谱中电偶极子跃迁与晶体场对称性的关系，进一步表征了稀土离子所处微晶晶格场的变化. 关键词： 微晶玻璃 探针 3+离子')" href="#">Eu³⁺离子     

Luminescence and scintillation of Eu2+‐doped high silica glass

High silica glass doped with Eu²⁺ ions was prepared as a scintillating material by impregnation of Eu ions into a porous silica glass followed by reduction sintering in CO atmosphere. A dominant emission band of the Eu²⁺ 5d–4f transition peaking around 430 nm was observed in the luminescence spectrum with the excitation peak around 280 nm and no emission from Eu³⁺ was present. Photoluminescence decay kinetics was governed by decay times of a few microseconds. The Eu²⁺‐doped high silica glass exhibited comparable energy resolution and slightly higher photoelectron yield with respect to the Bi₄Ge₃O₁₂ crystal in the pulse height spectra for X‐ray photon energies within 22–60 keV. Furthermore, a factor of 1.2 higher radioluminescence intensity was observed as well. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

钕离子掺杂和钕铝共掺高硅氧玻璃的光谱性质研究

基于多孔玻璃烧结的方法制备了钕离子掺杂和钕铝共掺高硅氧玻璃，测量了掺钕高硅氧玻璃的吸收光谱、荧光光谱和荧光寿命. 利用Judd-Ofelt理论计算得到了钕离子在高硅氧玻璃中的强度参数，计算并对比了掺钕高硅氧玻璃和钕铝共掺高硅氧玻璃的理论荧光寿命、受激发射截面和发光量子效率.讨论了钕铝共掺高硅氧玻璃中铝离子的掺入对玻璃发光性质的影响. 通过与其他掺钕氧化物玻璃和一些商用硅酸盐玻璃的主要光谱性质的比较，掺钕高硅氧玻璃显示了较好的光谱性质，有可能成为一种应用于高能和高频激光领域的新型激光材料. 关键词： 掺钕高硅氧玻璃 钕铝共掺 光谱性质 Judd-Ofelt理论     

Er,Yb:YAG微晶玻璃发光特性的研究

高温熔制Er³⁺，Yb³⁺离子掺杂CaO-Y₂O₃-Al₂O₃-SiO₂系统玻璃，并进行微晶化处理，研究了微晶玻璃中Er³⁺离子的发光及上转换发光特性，分析了微晶玻璃上转换发光机理.结果表明：原始玻璃经热处理得到了Er,Yb:YAG微晶玻璃，微晶玻璃中Er³⁺离子在室温下⁴I_13/2→⁴I_15/2跃迁产生横盖1450—1650nm区间的超宽带荧光，荧光半高宽达180nm，这可能由于YAG微晶相中Er³⁺离子与玻璃相中残留Er³⁺离子的共同发光；Er³⁺与Yb³⁺离子局域基质声子能量的降低使微晶玻璃Er³⁺离子上转换发光强度与原始玻璃相比显著提高，绿光、红光上转换荧光强度比玻璃样品分别增强约7和3倍；微晶化后Er³⁺，Yb³⁺离子局域环境发生变化也导致微晶玻璃中Er³⁺离子绿光、红光上转换发光相对强度发生变化. 关键词： 铒 镱:钇铝石榴石 微晶玻璃 荧光光谱     

氟化物、氟磷酸盐和磷酸盐玻璃中Er3+离子的发光研究

测定了氟化物、氟磷酸盐和磷酸盐玻璃中Er³⁺离子的吸收、荧光和激发光谱,解释了基质玻璃对Er³⁺离子发光的影响。进一步研究了在这三种基质玻璃中Er³⁺离子发光的浓度效应和温度效应,讨论了Er³⁺离子内和离子间的能量转移过程。 关键词：     

Electrochemical luminescence of n-type ZnO semiconductor electrodes doped with rare earth metals under the anodic polarization

Electrochemical luminescence (ECL) at n-type ZnO semiconductor electrode was measured under anodic polarization. Scanning the potential imposed on the ZnO electrode, emission was suddenly observed around +20 V. Using the ZnO electrodes doped with rare earth metal ions as Sm³⁺, Eu³⁺, Dy³⁺, Ho³⁺ and Er³⁺, much brighter emission was obtained than the ECL of non-doped ZnO. These emission spectra are ascribed to the rare earth metal ions, respectively. This result would show that emission centers of doped ions were selectively excited by electrons that were injected from electrolyte to the electrode by avalanche breakdown under strong anodic bias on the ZnO.     

Dy3+掺杂硼硅酸盐玻璃的发光特性

采用高温熔融法制备了Dy3+掺杂硼硅酸盐玻璃,通过测试激发光谱和发射光谱,研究了其光谱性质.研究了玻璃组分及Dy3+掺杂浓度对发射光谱及发光强度的影响,并计算了色坐标,均位于白光区域.通过改变玻璃组分及掺杂浓度,调节黄、蓝发射峰的强度比,在387 nm长紫外光激发下实现了单一基质上有效的白光发射.     

Sensitized fluorescence of Ce3+/Mn2+ system in phosphate glass

The preparation of sodium phosphate glasses singly and doubly doped with rare earth ion Ce³⁺ and transition metal ion Mn²⁺ by a melt quench method is described. The spectroscopic characterizations of the samples are conducted by absorption, excitation, and emission spectra. The orange red emission of divalent manganese sensitized by trivalent cerium ions in a phosphate glassy matrix has been investigated. Energy transfer (ET) from optically excited Ce³⁺ to Mn²⁺ in sodium phosphate glass, by nonradiative process is confirmed by fluorescence studies with various activator concentrations. The mechanism of ET is mainly electric dipole–dipole in nature.     

Luminescence properties of the Eu-doped porous glass and spontaneous reduction of Eu to Eu

The luminescent properties of Eu³⁺-doped porous glass were investigated and reduction of Eu³⁺ to Eu²⁺ was observed when the Eu³⁺-doped porous glasses were heat treated in air. The absorption, emission and excitation spectra of Eu³⁺-doped porous glasses were measured and the results significantly depended on the treating temperature. The integral intensity of Eu³⁺ and Eu²⁺ ions at different temperatures was also investigated to investigate this reduction process. Electron spin resonance (ESR) spectra of the samples were also measured, which also confirmed the reduction effect. A possible mechanism was discussed to explain this process.     

Spectroscopic features of Pr, Nd, Sm and Er ions in Li2O-MO (Nb2O5, MoO3 and WO3)-B2O3 glass systems

Li₂O-MO (Nb₂O₅, MoO₃ and WO₃)-B₂O₃ glasses doped with four rare earth ions, viz., Pr³⁺, Nd³⁺, Sm³⁺ and Er³⁺ (of 1.0 mol% each) were prepared. The glasses were characterized by X-ray diffraction, differential scanning calorimetry, ESR, optical absorption and photoluminescence spectra. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters Ω₂, Ω₄ and Ω₆ have been evaluated. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of these glasses. From this theory, various radiative properties like transition probability A, branching ratio β_r, the radiative life time τ_r and the emission cross-section σ^E for various emission levels of these glasses have been determined and reported. An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of all the three glasses. The analysis of the data indicated high non-radiative losses in Nb₂O₅ mixed glasses.     

Near-infrared broadband luminescence in Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-GeO<Subscript>2</Subscript> binary glass system

Near-infrared broadband luminescence from 1100 to 1600 nm was observed in Bi₂O₃-GeO₂ binary glasses. The strongest emission can be observed with 30 mol % Bi₂O₃ when pumped at 808 nm. The lifetimes of all samples are longer than 200 μs. The glass network was studied by Raman spectra and Bi⁺ ions are proposed as the infrared luminescence centers in this glass system. Thermal treatment in air results in partly oxidation of Bi⁺ to Bi²⁺.     

The effect of alkaline earth metallic ions on the photoluminescence properties of sol-gel silica glass

Mg²⁺-, Ca²⁺-, Sr²⁺- and Ba²⁺-doped silica glasses have been prepared using sol-gel processing by employing Si(OC₂H₅)₄, MgCl₂6H₂O, CaCl₂2H₂O, SrCl₂6H₂O and BaCl₂2H₂O as precursors, with HCl as a catalyst. The UV–visibleabsorption spectra of the doped samples are almost the same as those of the undoped sample. The absorption bands of alkaline earth metallic ions have not been observed in the doped samples. Strong visible light has been observed from sol- gel silica glasses doped with alkaline earth metallic ions. The relative fluorescence intensity of the Sr²⁺-doped (the impurity mole ratio of Sr²⁺ was 0.268%) and the Ba²⁺-doped (the impurity mole ratio of Ba²⁺ was 0.448%) samples was about 4 times that of the undoped sample. The relative fluorescence intensity of the Mg²⁺-doped (the impurity mole ratio of Mg²⁺ was 0.069%) sample was about 2.5 times that of the pure glass sample. The relative fluorescence intensity of the Ca²⁺- doped (the impurity mole ratio of Ca²⁺ was 0.179%) sample was about 3 times that of the pure glass sample. Alkaline earth metallic ions affect the formation and conversion of luminescent defects in sol-gel silica glass. Thus, the relative fluorescence intensity of the doped samples increases more than that of the undoped sample. Received: 17 April 2001 / Accepted: 6 June 2001 / Published online: 30 August 2001     

Spectroscopic properties of neodymium doped high silica glass and aluminum codoping effects on the enhancement of fluorescence emission

Nd³⁺-codoped and Al³⁺-Nd³⁺-codoped high silica glasses have been prepared by sintering nanoporous glasses impregnated with Nd³⁺ and Al³⁺ ions. The Judd–Ofelt intensity parameters Ω_2,4,6 of Nd³⁺-doped high silica glasses were obtained and used to analyze aluminum codoping effects. Fluorescence properties of Nd³⁺-doped high silica glasses strongly depend on the Al³⁺ concentration. While Nd³⁺ ion absorption and emission intensities of obviously increase when aluminum is added to Nd³⁺-doped high silica glasses, fluorescence lifetimes decrease and aluminum codoping has almost no influence on the radiative quantum efficiencies. This indicates that aluminum codoping is responsible for an anti-quenching effect through a local modification of rare-earth environments rather than through physical cluster dispersion. PACS 78.55.Qr; 42.70.-a     

The effect of Ce3+ ions on the spectral and decay characteristics of luminescence phosphate-borate glasses doped with rare-earth ions

The luminescent characteristics of Li₂O-B₂O₃-P₂O₅-CaF₂ (LBPC) glasses doped with Gd³⁺ and Tb³⁺ ions and codoped with Ce³⁺ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce³⁺ and Gd³⁺ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (⁶ P _J → ⁸ S _7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce³⁺ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed.     

Optical properties of sol-gel fabricated Mn/SiO2 nanocomposites: Observation of surface plasmon resonance in Mn nanoparticles

Manganese nanoparticles were grown in silica glass and silica film on silicon substrate by annealing of the sol-gel prepared porous silicate matrices doped with manganese nitrate. Annealing of doped porous silicate matrices was performed at various conditions that allowed to obtain the nanocomposite glasses with various content of metallic Mn. TEM of Mn/SiO₂ glass indicates the bimodal size distribution of Mn nanoparticles with mean sizes of 10.5 nm and 21 nm. The absorption and photoluminescence spectra of Mn/SiO₂ glasses were measured. In the absorption spectra at 300 nm (4.13 eV) we observed the band attributed to the surface plasmon resonance in Mn nanoparticles. The spectra proved the creation of Mn²⁺ and Mn³⁺ ions in silica glass as well. The absorption spectra of Mn/SiO₂ glasses annealed in air prove the creation of manganese oxide Mn₂O₃. The measured reflection spectra of Mn/SiO₂ film manifest at 240-310 nm the peculiarity attributed to surface plasmons in Mn nanoparticles.     

Infrared to visible upconversion luminescence in Er3+/Yb3+ doped titanate glass prepared by containerless processing

Er³⁺ doped TiO₂–La₂O₃ glasses modified by ZrO₂ have been successfully fabricated by the containerless method with incorporated Yb³⁺ ions as sensitizers. Under the excitation of 980 and 808 nm diode lasers, visible emissions centered at 534, 554 and 674 nm are observed, which are assigned to the Er³⁺ transitions of ²H_11/2→⁴I_15/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2, respectively. The emission signals are so strong that they can be observed by naked eyes even at pumping power as low as 20 mW. Measurements of pump-power dependent intensity and time-resolved decay behavior of upconversion luminescence show that two-photon excited state absorption (ESA) and energy transfer (ET) between rare earth ions are the predominant mechanisms for upconversion emissions. Besides, the intensity of upconversion luminescence has been enhanced by increasing the concentration of ZrO₂ in these rare earth doped bulk titanate glasses.     

Luminescence of yttrium niobium-tantalate doubly activated by europium and/or terbium under X-ray and electron beam excitation

This paper reports the luminescence emission spectra of Y(Ta,Nb)O₄ activated by rare earth ions such as Eu³⁺ and Tb³⁺. The influence of these rare earth ions on the luminescence of yttrium niobium-tantalate phosphors was investigated. The luminescent properties were studied under X-ray and electron beam excitations. Under these excitations, the emission centers of the rare earth activators (Eu³⁺,Tb³⁺) were found to contribute efficiently to the overall luminescence. Changing the mol concentration of the incorporated activators resulted in a broad variation of visible photoluminescence. Color cathodoluminescence images showed clearly the dependence of chromaticity on the different activators. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing a broad variation of visible photoluminescence from blue to red.     

Luminescence properties and radiation response of sodium borate glasses scintillators

We examined basic luminescence properties and radiation response of sodium borate glass scintillators activated with Pb²⁺, Cu⁺, Ti⁴⁺, V⁵⁺, W⁶⁺ and Yb³⁺ ions, respectively. These glasses had more than 80% transparency for emission wavelength range, and strong absorption bands due to the charge transition of the ions were observed. In the photoluminescence spectra, all glasses demonstrated intense emission peak in visible region, which are corresponding to the ions with s² (Pb²⁺), d¹⁰ (Cu⁺) and d⁰ (Ti⁴⁺, V⁵⁺, W⁶⁺) configuration. Additionally charge transfer emission was observed in Yb³⁺-doped glass. When ²⁴¹Am 5.5 MeV alpha-ray excited the glasses, they showed weak emission intensity because of low energy transfer efficiency from host lattice to emission center. By ²⁴¹Am irradiated pulse height spectra, Cu⁺-doped glass demonstrated the highest scintillation output in the glasses.     

Investigation on luminescence and energy transfer in Tb-doped lead telluroborate glasses

This work reports on the visible luminescence properties and energy transfer processes responsible for non-exponential nature of the decay curves and also quenching of luminescence intensity of the ⁵D₃→⁷F_J transitions of Tb³⁺ ions in lead telluroborate (PTB) glasses containing different Tb³⁺ concentrations. The XRD and FT-IR spectra were measured to study the glassy nature and composition of the prepared glasses. The radiative properties are determined using the Judd-Ofelt theory to judge the suitability of studied glasses as practical photonic material. These parameters suggest that the PTBTb20 glass has the potential to produce intense green emission (544 nm) through the ⁵D₄→⁷F₅ transition.     

Thermal and optical properties of Er-doped oxyfluorotellurite glasses

Er³⁺-doped oxyfluorotellurite glasses with four different concentrations of Er³⁺ ions have been prepared and investigated their thermal, optical absorption, excitation and luminescence properties. From the DSC spectra, glass transition and onset of crystallization temperatures have been found. Judd-Ofelt intensity parameters have been derived from the absorption spectrum and are in turn used to calculate radiative properties for the important luminescent levels of Er³⁺ ions. The calculated radiative properties are comparable to experimental values. The glasses show intense green and weak red emission under normal excitation with 451 nm. The decrease in emission intensities and lifetimes of the ⁴S_3/2 level with concentration of Er³⁺ ions has been explained as due to energy transfer processes between Er³⁺ ions. The stimulated emission cross-sections and quantum efficiencies of the green and infrared emissions have been determined. The results indicate that the glasses may be suitable for use as a laser medium in making solid-state green laser by normal pumping route and as laser medium and optical amplifier in the 1.5 μm region.