Photoacoustic Spectra of Sm3+, Eu3+, Dy3+ Complexes

The complexes crystals of Sm(Ac)3.4H₂O, Eu(Ac)3.4H₂O and a new complex Dy2(Ac)(NO3)4.12H₂O were synthesized and their PA spectra were determined firstly. All their PA spectra absorptions are interpreted. The fluorescence properties of Sm³⁺, Eu³⁺, Dy³⁺ and the relaxation process models were studied by their PA spectra.     

多体系多波长计算光度法同时测定镧铈镨钕钐铕钆

本文以DBC-偶氮氯膦为显色剂,并且在显色体系中加入不同量的EDTA-Na2P2O7作为竞争配位剂,使得七组分轻稀土组分间吸收光谱灵敏度的差别逐渐加大,从而增加了轻稀土混合物体系组分间吸收光谱的线性独立性.利用数值稳定性较强的约束优化算法--可变容差法处理光谱数据,对不同浓度比例的七组分轻稀土混合物体系(La3+,Ce3+,Pr3+,Nd3+,S m3+,Eu3+,Gd3+)的测定,取得了较满意的结果.     

ZBLAN玻璃中Nd3+,Tm3+,Yb3+的上转换发光特性

采用高温固相法制备了Nd,Tm和Yb掺杂的ZBLAN玻璃上转换材料.Tm3+,Yb3+的摩尔浓度分别固定为0.01%,0.3%,Nd3+摩尔浓度变化范围为0.1%～2%.在室温下,测试了样品在300～1 000nm间的吸收光谱.在798 nm近红外光激发下,测试了样品的上转换光谱.实验发现,样品在798 nm红外光激发下发出了较强的多波段(红,蓝和绿)的可见光.由上转换可见光各波段的发射谱线,给出了能级跃迁机制.蓝光主要来源于Tm3+的激发态1G4到基态3H6的跃迁,绿光来源于Nd3+的2H7/2到基态4I9/2的跃迁,红光来源于Nd3+的2H11/2到基态4i9/2的跃迁.研究发现,在Nd3+,Tm3+,Yb3+:ZBLAN玻璃样品中存在激发态吸收,能最转移和交叉弛豫等上转换过程.其发光机理是Nd3+,TM3+和Yb3+离子之间的能量转移.根据Nd3+摩尔浓度不同其上转换发光强度不同,分析了掺入稀土的浓度对上转换发光效率的影响.当Nd3+浓度为1.5%(摩尔分数)时上转换发光最强,大于1.5%后发光开始减弱.     

CaS∶Eu~(2+),Sm~(3+)的制备与表征

采用湿法工艺在还原气氛下制备了CaS∶Eu2+,Sm3+光存储材料。研究了灼烧温度和灼烧时间对样品性能的影响。XRD图谱表明,样品在700℃—1200℃均形成CaS晶格。光谱分析表明,在紫外光(295nm)激发后,用980nm半导体激光照射样品,具有光激励发光现象,发射光谱峰值波长为649nm。     

Luminescence properties of Eu3+ and Sm3+ coactivated Gd(III) tungstate phosphor for light-emitting diodes

Rare-earth ions coactivated red phosphors Gd_0.2RE_1.8(WO₄)₃ (RE=Eu³⁺ and Sm³⁺) were synthesized by conventional solid-state reaction using boric acid as a flux agent. The samples were characterized by X-ray diffractometer (XRD), energy-dispersive X-ray spectrometer (EDS) and luminescence spectrometer (LS). The results showed that the Eu–Sm system exhibits higher emission intensity than those of the Eu single-doped system and Sm separate-doped system under ultraviolet (UV) radiation. Samarium(III) ions are effective in broadening and strengthened absorptions around 400 nm. Furthermore, it exhibits enhanced luminescence emission. when the mole ratio of boric acid is about 0.16, the luminescence capability is optimum. Two strongest lines at ultraviolet (394 nm) and blue (465 nm) in excitation spectra of these phosphors match well with the output wavelengths of UV and blue GaN-based light-emitting diodes (LEDs) chips.     

NaYF4:Eu3+,Tm3+,Yb3+材料中Stokes和反Stokes发光研究

合成了Eu3+,Tm3+和Yb3+掺杂的NaYF4材料.360 nm光激发呈蓝色发光,峰值位于452 nm,对应Tm3+的1D2→3F4跃迁;395 nm光激发旱橙色发光,峰值位于591 nm,对应Eu3+的5D0→7F1跃迁;409 nml光激发呈红色发光,峰值位于613 nm,对应Eu3+的5D0→7F2跃迁;980 nm光激发呈蓝色和红色发光,发光峰位于474和646 nm.蓝光来源Tm3+的1G4→3H6跃迁,红光来源Tm3+的1G4→3F4跃迁.在双对数曲线中,蓝光474 nm和红光646 nm的斜率分别为2.1和2.4,在980 nm光激发下,蓝光和红光发射都是双光子过程.还研究了材料的吸收光谱,并利用X射线衍射,扫描电镜测试了材料的物相结构和微观彤貌.结果表明:NaYF4:Eu3+,Tm3+,Yb3+材料具有较规则的六方相结构,结品良好.     

Preparation and photoluminescence properties of the Eu2+, Sm3+ co-doped Li2SrSiO4 phosphors

A series of Eu²⁺ and Sm³⁺ co-doped Li₂SrSiO₄ phosphors are prepared by the high temperature solid-state reaction. The morphology, structure and spectroscopic properties of the prepared samples are characterized by scanning electron microscopy, X-ray diffraction, diffuse reflection spectra, photoluminescence spectra and electron paramagnetic resonance spectra, respectively. The effect of Sm³⁺ doping concentration on the photoluminescence intensity of the prepared samples is also investigated. The results indicate that the crystal structure of Li₂SrSiO₄ is not changed with the Eu²⁺, Sm³⁺ co-doping. The spherical-like particle size of the obtained product is about 20–30 nm in diameter. When the Sm³⁺ concentration is 0.3 mol% and the Eu²⁺ concentration is 0.7 mol%, the phosphors show the maximum emission intensity, which is 50% higher than that of Eu²⁺ doped Li₂SrSiO₄. Excited at 420 nm, the phosphor presents a single broad emission band peaking at 558 nm, which is ascribed to the 4f⁶5d¹ → 4f⁷ transitions of Eu²⁺ and ⁴G_5/2 → ⁶H_5/2 and ⁴G_5/2 → ⁶H_7/2 transitions of Sm³⁺. The Commission International de I′Eclairage chromaticity coordinates of Li₂SrSiO₄:0.7 mol% Eu²⁺, 0.3 mol% Sm³⁺ are x = 0.28, y = 0.28.     

Li~+、Na~+和Eu~(3+)共掺Lu_2O_3的制备及发光特性研究

用高温固相法合成了不同掺杂浓度的Li~+、Na~+和Eu~(3+)共掺Lu2O3闪烁体发光材料,使用XRD进行结构表征,用扫描电镜观察了样品形貌,测量了激发光谱、发射光谱,分析了Li+、Na+和Eu3+的掺杂浓度以及温度对合成样品发光强度的影响。结果显示,Li~+、Na~+掺杂摩尔分数分别为2.5%和1%,在800℃空气中煅烧2 h制备的Lu2O3∶5%Eu~ (3+)样品的发光最强。在同样条件下,比单掺2.5%Na+的样品发光强度提高1.89倍,比单掺2.5%Li+的样品发光强度提高3.97倍,比不掺Li+和Na+的样品发光强度提高6.43倍。     

Luminescence properties of Y2O3:Bi3+, Ln3+ (Ln=Sm,Eu, Dy,Er, Ho) and the sensitization of Ln3+ by Bi3+

The spectroscopic characterization of yttria, singly and doubly doped with Ln³⁺ (Ln=Sm, Eu, Dy, Er, Ho) and Bi³⁺ ions, is performed through excitation spectra, emission spectra and decay time measurements. The obtained spectroscopic data clearly indicate that energy transfer takes place from Bi³⁺ to Ln³⁺ ions. The energy transfer efficiency of Bi³⁺→Ln³⁺ and quantum efficiency of Ln³⁺ were calculated. Upon excitation of 370 nm (Bi³⁺ excitation band), the quantum efficiency of Ln³⁺ varies from ～4% to ～44%. The energy transfer efficiency increases continuously with increasing Ln³⁺ concentrations, whereas the variation of the quantum efficiency of Ln³⁺ is complicated. The quantum efficiency of Ln³⁺ is discussed in terms of electron transfer and cross relaxation.     

Eu3+．Dy3+,Sm3+掺杂Ca(Sr,Ba)W04的光谱性质

采用共沉淀方法制备了稀土离子Eu3+,Dy3+,Sm3掺杂的Ca(Sr,Ba) WO4发光材料,目的是研究金属阳离子改变对稀土离子发光性质的影响.X射线衍射光谱数据表明,CaWO4、SrWO4、BaWO4都是四方晶系I41/a(88)结构,随着阳离子半径增大,衍射峰向小角移动.不同温度制备的BaWO4样品X射线衍射光谱数据表明,温度较低时制备的晶体样品X射线衍射峰较宽;当制备温度升高后,晶体样品X射线衍射峰宽变窄.样品的SEM照片表明,低温制备的样品晶粒尺寸较小,约为100～300 nm;高温制备样品晶粒尺寸较大,约为2～6 μm.测试了Eu3+,Dy3+,sm3+掺杂的Ca( Sr,Ba) WO4发光材料的激发和发射光谱.计算了Eu3+掺杂的Ca(sr,Ba) WO.的J-O强度参数Ωλ(λ=2,4),Ω2值随着阳离子半径增大迅速减小,经分析它是导致Eu3+掺杂的Ca(Sr,Ba) WO4的发射强度随着阳离子半径增大迅速减弱的原因.然而Sm3+掺杂的SrWO4其他两种晶体相比,其发射强度反而增强.根据激发光谱和文献报道,我们认为可能是由于钨酸根离子与稀土离子的能量传递引起的.从Dy3+,Sm3+掺杂的Ca(Sr,Ba)WO4的发射光谱可以看到,随着阳离子半径增大发射峰蓝移,发射峰的Stark劈裂减弱.我们用位形坐标图解释了这一现象产生的原因.     

Eu和Dy包覆纳米ZnO的发光特性的研究

通过共沉淀法制备了Eu和Dy包覆的纳米ZnO材料.X射线衍射被用来测量样品的结构和粒径.光致发光测量显示325 nm的紫外光能很好激发Eu3+的612 nnm的红光发射和Dy3+的484和575 nm发射,显示氧化锌基质与Eu3+和Dy3+之间实现了能量传递,并对能量传递的机制进行了讨论.在Eu和Dy共同包覆的样品中,通过能量传递可能在紫外激发下实现白光发射.     

Mössbauer studies of57Fe intercalated CdPS3

The results of Mössbauer Investigation of⁵⁷Fe, Intercalated in layered CdPS₃ of two differrent concentrations (0.05, 0.1) of iron point out that the guest species occupies three distinguishable sites in the Van der Waals gap and exhibits three doublets. Moreover, for the case of Fe_0.1 CdPS₃ in addition to these three doublets arising from Fe²⁺, three sets of magnetically split patterns Indicating ordering appear. The isomer shift, quadrupolar splitting, and Internal magnetic field for all the specimens studied, have been measured.     

Luminescence properties of NaGd(PO3)4:Eu3+ and energy transfer from Gd3+ to Eu3+

The luminescence properties of polyphosphates NaEu _x Gd_(1?x)(PO₃)₄ (x = 0–1.00) and the energy transfer from Gd³⁺ to Eu³⁺ were studied. In undoped NaGd(PO₃)₄ sample, the photon cascade emission of Gd³⁺ was observed under ⁸S_7/2 → ⁶G_J excitation (201 nm) in which the emission of a red photon due to ⁶G_J → ⁶P_J transition is followed by an ultraviolet photon emission due to ⁶P_J → ⁸S_7/2 transition. When part of Gd³⁺ ions in the host NaGd(PO₃)₄ were substituted by Eu³⁺ ions, the NaGd(PO₃)₄:Eu³⁺ sample showed intensive red emission under 172-nm vacuum-ultraviolet (VUV) excitation which is suitable for mercury-free fluorescent lamps and plasma display panel applications. Based on the VUV–visible spectroscopic characteristics and the luminescence decay properties of NaGd(PO₃)₄:Eu³⁺, it was found that the quantum cutting by a two-step energy transfer from Gd³⁺ to Eu³⁺ can improve the red emission of Eu³⁺ ions under VUV excitation but only a part of the excitation energy in the excited ⁶P_J states within Gd³⁺ ions can be transferred to Eu³⁺ ions for its red emission, and the nonradiative energy transfer efficiencies from the excited ⁶P_J states within Gd³⁺ to Eu³⁺ were calculated.     

Optical properties of Sm3+:CaO-Li2O-B2O3-BaO glass and codoped Sm3+:Eu3+:

Calibo glasses of Sm³⁺ with and without BaO have been synthesized and the optical properties (like absorption and photoluminescence) analyzed in terms of Judd–Ofelt theory. The fluorescence yield of Sm³⁺ enhances with BaO, and is optimum at 10% BaO. The effect of temperature on the energy transfer probability in (Sm³⁺:Eu³⁺) codoped glass has been reported and it can be inferred that the combination may serve as a temperature sensor. PACS 42.70.Ce     

Ce3+离子敏化Eu3+∶Cr3+∶Sm3+∶YAG外延层的荧光现象

对Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG处延层中的荧光敏化现象进行了报道和分析 ,在较高浓度的Ce3+ 离子掺杂时 ,外延层在蓝色、绿色波段出现了新的荧光谱线 ,可解释为在Ce3+ 离子敏化作用下 ,Eu3+ 离子产生了由高位激发态能级5Di(i=1,2 ,3)直接到基态能级7Fj(j =0 ,1,2 ,3)的辐射跃迁过程 ,并且这种Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG外延层还是一种新颖的白色单晶荧光材料。     

Photoluminescence properties and energy transfer of Ca3WO6:Sm3+ co-doped Eu3+

A reddish-orange phosphor, Ca₃WO₆:Sm³⁺, was synthesized by the convenient solid-state reaction method and characterized by X-ray diffraction (XRD). Photoluminescence properties and concentration quenching of Ca₃WO₆:Sm³⁺ phosphor have been discussed in the excitation and emission spectra. Ca₃WO₆:Sm³⁺ phosphor is able to generate a strong excitation peak, which matches the emission wavelength from near-UV LEDs. Energy transfer from Sm³⁺ to Eu³⁺ in Ca₃WO₆ host is observed and investigated in detail. The chromaticity coordinates of Ca₃WO₆:Sm³⁺ can be regulated to approach the NTSC standard values of red phosphor by codoping Eu³⁺ ions. The photoluminescence properties suggest that novel Ca₃WO₆:Sm³⁺, Eu³⁺ phosphor might have a potential application for near-UV LEDs.     

Luminescence properties of the compounds of Eu3+ and Tb3+ with some aromatic acids

The excited states of some organic acids are calculated in the electron approximation taking into account the n electrons. The calculations were performed by two methods: in the frozen core approximation (method of the potential V(^N–1)) and by a method which enables taking into account the relaxation of the electronic core accompanying the excitation of the electron in the molecule. The luminescence properties of the compounds studied with Eu³⁺ and Tb³⁺ are studied based on the calculations performed. The results are compared with experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 53–57, February, 1986.     

Synthesis and photoluminescence properties of YVO4:Eu3+, Al3+ phosphor

The Y_0.95?xAl_xVO₄:5%Eu³⁺ (0≤x≤0.1) phosphors were successfully synthesized by solid state reaction at 900 °C for 6 h, and their luminescence properties were investigated under UV and VUV excitation. Monitoring at 619 nm, a strong broad absorption was enhanced by co-doping of Al³⁺ into the YVO₄:Eu³⁺ lattices at 256 nm under UV excitation. The VUV excitation spectra also showed the enhanced excitation bands at about 156 and 200 nm. Under 254 or 147 nm excitation, it was found that Y_0.95?xAl_xVO₄:Eu³⁺(0≤x≤0.1) phosphors showed strong red emission at about 619 nm corresponding to the electric dipole ⁵D₀^–7F₂ transition of Eu³⁺. The improvement of luminescence intensity of YVO₄:Eu³⁺ was also observed after partial substituting Y³⁺ by Al³⁺ and the optimal luminescence intensity appeared with incorporation of 2.5 mol% Al³⁺.     

Synthesis and luminescence properties of Eu3+,Bi3+-doped BaWO4 phosphors

BaWO₄:Eu³⁺,Bi³⁺ phosphors have been prepared by the conventional high-temperature solid-state reaction and chemical precipitation. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) technologies. When the phosphors are prepared by the high-temperature solidstate reaction, Bi³⁺ doping into BaWO₄:Eu³⁺ can increase the emission intensity of 613 nm. However, maximum emission at about 595 nm was observed in Eu³⁺,Bi³⁺-doped BaWO₄ phosphors prepared by the chemical precipitation. The decay constants (monitored at 595 and/or 613 nm) are within 45–100 s. The color purity of the Ba_0:865WO₄: Eu_0:11,Bi_0:025 phosphor (prepared by chemical precipitation) was 100%. The emission mechanism of Eu³⁺,Bi³⁺ in the BaWO₄ phosphors is briefly discussed.