Synthesis and characterization of submicron PMMA particles containing rare earth ions on the surface

Emulsifier‐free emulsion polymerization was adopted to synthesize rare earth containing submicron polymer particles under microwave irradiation. To control the size and distribution of the particle, the relationship between reaction time, monomer content, and particle radius was studied for the polymerization of methyl methacrylate (MMA) in the absence and presence of rare earth ions, in which water was used as solvent, and potassium persulfate was used as initiator. In the latter polymerization, the solution of MMA and europium octanoate (EOA) was used instead of MMA itself as EOA can be dissolved in MMA within certain concentrations, and the result shows that the polymerization process is affected by existence of EOA except when the amount of MMA is 2 ml. For particles containing rare earth ions, characterization shows that mole percentage of Eu(III) ion in the surface layer with a thickness of 5 nm, which is estimated from X‐ray photo electron spectroscopy (XPS), is always larger than the value estimated by inductively coupled plasma atomic emission spectrometer (ICP‐AES) for the whole particle, indicating that surface enrichment of rare earth ions took place during the polymerization. Further characterization by XPS depth measurement after Ar⁺ sputtering shows the same result. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1124–1131, 2003     

Photosensized controlling benzyl methacrylate-based matrix enhanced eu(3+) narrow-band emission for fluorescence applications

This study synthesized a europium (Eu(3+)) complex Eu(DBM)(3)Cl-MIP (DBM = dibenzoyl methane; Cl-MIP = 2-(2-chlorophenyl)-1-methyl-1H-imidazo[4,5-f][1,10]phenanthroline) dispersed in a benzyl methacrylate (BMA) monomer and treated with ultraviolet (UV) light for polymerization. Spectral results showed that the europium complex containing an antenna, Cl-MIP, which had higher triplet energy into the Eu(3+) energy level, was an energetically enhanced europium emission. Typical stacking behaviors of π-π interactions between the ligands and the Eu(3+)-ion were analyzed using single crystal X-ray diffraction. Regarding the luminescence performance of this europium composite, the ligand/defect emission was suppressed by dispersion in a poly-BMA (PBMA) matrix. The underlying mechanism of the effective enhancement of the pure Eu(3+) emission was attributed to the combined effects of structural modifications, defect emissions, and carrier charge transfer. Fluorescence spectra were compared to the composite of optimized Eu3+ emission where they were subsequently chelated to four metal ions via carboxylate groups on the BMA unit. The optical enhanced europium composite clearly demonstrated highly efficient optical responses and is, therefore a promising application as an optical detection material.     

A carbazole–triphenylamine copolymer‐bearing pendant europium complexes: Synthesis and luminescence properties

A novel carbazole–triphenylamine copolymer‐bearing pendant bipyridine PM1TPA and corresponding europium (III) complexed polymer PM1TPA–Eu–x, in which the values of x are 0.1, 0.5, and 1.0 representing the molar ratio of bipyridine ligands complexed with Eu(III), were designed and synthesized. Their chemical structures were confirmed by ¹H NMR, FT‐IR, and elemental analysis. Both PM1TPA and PM1TPA–Eu shows good solubility in common organic solvents such as tetrahydrofuran (THF) and CHCl₃. The 5% weight loss temperature (T_d^5%) of PM1TPA and PM1TPA–Eu–1.0 are 363^oC and 306^oC, respectively. The photoluminescence (PL) spectra of PM1TPA–Eu in solution consists of two emission bands, one in the 400–570 nm region and another at 612 nm, corresponding to the emission of polymer main chain and europium complexes, respectively. When the concentration of PM1TPA–Eu–1.0 in THF solution increases, the PL intensity in the 400–570 nm regions became more and more weaker. And only the characteristic emission of europium complex was observed in the solid film, which indicates that the excited energy absorbed by the polymer backbone was efficiently transferred to the europium complexes. Furthermore, nearly monochromatic red electroluminescence from europium complex was observed from the polymeric light‐emitting diode using PM1TPA–Eu–1.0 as the emissive layer under 25 V forward bias. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42746.     

聚苯乙烯-聚4-乙烯基吡啶-稀土铕(Ⅲ)发光配合物的微观结构及荧光性能表征

含共轭结构氮杂环的非离子嵌段共聚物能与铕(Ⅲ)络合反应形成发光配合物,研究了该发光配合物的配位结构及其荧光性能。以聚苯乙烯-聚4-乙烯基吡啶(PS-b-P4VP)作为高分子配体,以邻菲罗啉(Phen)作为小分子配体,通过吡啶环的氮原子与Eu(Ⅲ)离子配位发生络合反应形成了以网状的Eu(Ⅲ)-P4VP核层以及PS链段为壳层的共聚物-稀土配合物,通过电子透射电镜(TEM)分析了其微观形态结构。用荧光分光光度计分别表征了嵌段聚合物-稀土铕(III)配合物不同链段的荧光发光强度并且进行了荧光强度的对比。此外,还研究了不同的Eu(Ⅲ)离子浓度对荧光强度的影响,得到了制备共聚物-稀土配合物荧光的最佳Eu(Ⅲ)离子浓度。     

Copolymers of styrene with a quaternary europium complex

A complex of Eu³⁺, benzoate (BA), acrylate (AA), and 1,10‐phenanthroline (Phen) was synthesized in this work. The structure of Eu(BA)₂(AA)(Phen) was characterized with elemental analysis, FTIR, and UV spectroscopy. Copolymers containing rare earth complex were prepared via the copolymerization of Eu³⁺(BA)₂(AA)(Phen) with styrene. Semitransparent, luminescent polymer materials with high fluorescent intensity were obtained. The as‐synthesized materials were further characterized by means of IR and UV spectra, which indicated that they were copolymers instead of blends. The fluorescence spectra of the copolymers revealed the intense UV absorption characteristics of the rare earth complex present in the materials, as long as only a small portion of the complex was incorporated into the copolymers. Moreover, thermal analysis showed that the copolymer had excellent heat stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1506–1510, 2006     

白光LED用稀土离子掺杂硼硅酸盐玻璃的发光性能

用熔体淬冷法在空气中制备了稀土(Tm,Dy,Tb,Eu)离子单掺和共掺的硼硅酸盐发光玻璃.研究了制得玻璃的发射光谱和激发光谱特性.结果表明:Eu离子单掺玻璃的发射光谱中出现了Eu2 和Eu3 的特征发射带,证明在此玻璃系统中,有部分Eu3 转化为Eu2 .Eu3 →Eu2 的转化效率与玻璃基质中B2O3的含量和网络调整体的类型有关,并且Eu2 的发射峰随玻璃基质中碱土离子半径的增大而出现红移.Eu/Dy和Tm/Tb/Eu共掺的硼硅酸盐玻璃的发射光谱中出现蓝、黄/绿、红发射带.这些发射带的复合可以使玻璃在紫外光激发下产生白光,并且各发射带的强度比例可以通过改变玻璃基质的组成来调节,表明所制备的稀土离子掺杂硼硅酸盐发光玻璃有可能取代荧光粉应用于制备白光发光器件.     

苯丙烯酸邻菲罗啉铕钇配合物的合成及荧光特性

在乙醇介质中，合成了标题化合物，测定了其组成，红外光谱及荧光光谱，结果表明，羧酸的羟基氧及邻菲罗啉中的氮原子均与稀土离子配位，铕钇配合物的荧光强度值高于铕配合物。     

Design and intelligent colour regulation of luminescent silk chemically bonded with Eu(III) and Eu(III)/Tb(III)

Design and successful synthesis of a series of novel luminescent silk chemically modified with europium(III) [Eu(III)] and europium(III)/terbium(III) [Eu(III)/Tb(III)] is reported. The modified silk specimens were characterised by infrared spectroscopy, fluorescence spectroscopy, scanning electron microscopy, and evaluated for their colour fastness. The rare earth ions were linked to the silk fibre via chemical bonds with the aid of tetracarboxylic acids used as the bridging ligands. Therefore, the modified silk had excellent luminescent stability and colour fastness to water and sunlight. Based on the blue fluorescence of silk along with the red and green luminescence of Eu(III) and Tb(III), respectively, under ultraviolet irradiation intelligent colour regulation was easily achieved by adjusting either the amount of Eu(III) or the ratio of Eu(III)/Tb(III). The Commission International de l'Eclairage chromaticity co‐ordinates calculated from the emission spectra also confirm the colour changes. Benefiting from the tunable colour and high stability, the modified silk could be an excellent candidate for applications in anti‐counterfeiting and flexible tunable light‐ emitting materials.     

Local microstructure characterization of rare earth‐doped PMMA with low‐ion content by fluorescence EXAFS

Fluorescence‐extended X‐ray absorption fine structure (EXAFS), and emission spectrum and excitation spectrum (ESES) were used to characterize the local structure of rare earth‐doped poly(methyl methacrylate)s (Re‐PMMAs) with ion concentration of 600–1000 ppm. Fluorescence EXAFS shows that the chemical state of Sm in Sm‐PMMA is the same as that in Sm₂O₃ and samarium octanoate (SOA), while that of Eu in Eu‐PMMA is different from that in Eu₂O₃ and europium octanoate. ESES also proves the concomitance of Eu²⁺ with Eu³⁺ ions in Eu‐PMMA. And, the almost identical peak positions of Eu L₃ edge at ～6976.7 eV in fluorescence EXAFS of Eu‐PMMA with various Eu content suggests the proportions of Eu²⁺ to Eu³⁺ are the same in these samples. The simulation of fluorescence EXAFS shows that the first‐shell coordination number of Sm³⁺ in Sm‐PMMA is 9.12, and the average first‐shell distance around Sm³⁺ in Sm‐PMMA is 2.43 Å. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1294–1298, 2006     

Er3+ Ions‐Doped Germano‐Gallate Oxyfluoride Glass‐Ceramics Containing BaF2 Nanocrystals

Er³⁺ ions‐doped germano‐gallate oxyfluoride glass‐ceramic containing BaF₂ nanocrystals was prepared through conventional melt quenching and subsequent thermal treatment method. X‐ray diffraction patterns and transmission electron microscope images confirmed the formation of BaF₂ nanocrystals in glass‐ceramics. Preferential incorporation of Er³⁺ ions into the BaF₂ nanocrystals were confirmed by the absorption spectra and emission spectra, and enhanced upconversion emission and infrared emission were observed. Relatively high transmittance in the mid‐infrared region indicated great potential of this germano‐gallate oxyfluoride glass‐ceramics as host materials for the efficient mid‐infrared emission from rare‐earth ions.     

The separation of europium from a middle rare earth concentrate by combined chemical reduction,precipitation and solvent-extraction methods

The chemical reduction of pure europium(III) chloride solutions was investigated using reagents comprising reactive metals (Zn and Mg), metal amalgams (Zn-Hg, Na-Hg and Eu-Hg), metal hydride (NaBH₄) and nitrogenous reductants (N₂H₄ and NH₂OH). Using 100% excess of reducing agent and of ammonium sulphate, efficient precipitation of europium(II) sulphate was obtained with the metal amalgams (99·7–99·9%) and with zinc metal (99·8%), whereas only partial precipitation was obtained with magnesium metal (69%), and no precipitation was observed with the other reagents. Application of the method to synthetic rare earth chloride solutions containing europium 7·5, neodymium 5, samarium 35 and gadolinium 20 g dm⁻³ gave efficient precipitation of europium(II) sulphate with zinc and europium amalgams, but no selective precipitation with sodium amalgam. Reduction of an authentic middle rare earth chloride solution with zinc amalgam gave 97·5% recovery of europium(II) sulphate containing (as a percentage of the total rare earths) europium 92, samarium 3·5, neodymium 2, cerium 1, praseodymium 0·6 and gadolinium 0·5%. Conversion of the europium(II) sulphate to europium(II) chloride, followed by re-precipitation of the sulphate increased the europium content only to 96·5%, whereas replacement of the re-precipitation by solvent extraction of the trivalent rare earth impurities into solutions of commercial organophosphorus or carboxylic acids in xylene increased the europium content to > 99·98%. The zinc ions introduced into the middle rare earth mother liquor during the reduction procedure can be removed by solvent extraction into a commercial phosphine oxide (Cyanex 925), without loss of rare earth values.     

Effect of BaF2 Content on Luminescence of Rare‐Earth Ions in Borate and Germanate Glasses

Rare‐earth‐doped oxyfluoride germanate and borate glasses were synthesized and next studied using spectroscopic methods. Influence of fluoride modifier on luminescence properties of rare earths in different glass hosts was examined. The excitation and emission spectra of Pr³⁺ and Er³⁺ ions in the studied glasses were registered. The emission spectra of Pr³⁺ ions in germanate and borate glasses are quite different and depend strongly on the glass host. In samples doped with Er³⁺ ions emission bands located around 1530 nm corresponding to the main ⁴I_13/2→⁴I_15/2 laser transition were registered, independently of the glass host. Quite long‐lived near‐infrared luminescence of Er³⁺ ions was observed for germanate glasses with low BaF₂ content, while in borate glass systems influence of barium fluoride on luminescence lifetimes is not so evident. The Judd–Ofelt calculations were used in order to determine quantum efficiencies of excited states of rare‐earth ions in germanate and borate glasses.     

Photoluminescence of Ag Nanoparticles and Tm3+ Ions in the Bismuth Germanate Glasses for the Blue Light‐Excited W‐LED

Materials containing rare‐earth ions and Ag nanoparticles (NPs) have been widely applied due to prior demonstration of increase in their luminescence properties. Here, Tm³⁺ ions‐doped bismuth germanate glasses were synthesized by a chemical reduction method based on the conventional melting‐quenching technique. The Ag NPs were facilely precipitated in the glass matrix by the chemical reduction method during the annealing process. TEM image shows that the Ag NPs are closely dispersed in the glass matrix. The luminescence properties and energy‐transfer mechanism were systematically investigated by means of absorption, emission, and excitation spectra. Significant enhancements of Tm³⁺ ions emission and a broad emission band centered at 568 nm caused by Ag NPs are observed upon 474‐nm excitation. Our research may illustrate the interactions between Tm³⁺ ions and Ag NPs and provide a simplified way to synthesize the high‐efficiency luminescent materials for the blue light‐excited W‐LEDs.     

Low-temperature solid-state synthesis and luminescent performance of a novel Li2NaBP2O8-based phosphor activated with europium (III)

For the application of inorganic phosphors in solid-state lighting field, exploring a synthesis route with low energy consumption and low cost is the current research focus. In this study, a low-temperature solid-state synthesis route for a novel Li₂NaBP₂O₈:Eu³⁺ (LNBP:Eu) phosphor is reported. The phase structure, morphology, and elemental composition of its powder phase are characterized. According to photoluminescence and X-ray photoelectron spectroscopy data, the occupancy site and oxidation state of doping europium are discussed. Under near-UV (395 nm) excitation, the powder phase exhibits reddish-orange emission with a dominant ⁵D₀ → ⁷F₁ transition of europium. The intensity of visible photoluminescence is closely influenced by the europium doping content. The optimal content is 0.04 mol, and concentration quenching is ascribed to energy transfer among the nearest-neighbor europium ions. Moreover, chromatic properties are investigated in detail. The obtained data show that the LNBP:Eu powder phase is a prospective phosphor for application in near-UV-converted warm white light-emitting diodes.     

对羟基苯甲酸稀土(铕)配合物及其荧光纤维的制备

合成了Eu3+与对羟基苯甲酸、1,10-邻菲啰啉(phen)的具有新型结构的稀土配合物。通过TEM、元素分析、IR、TG及荧光光谱分析对其表观形貌、粒径、组成结构及荧光性能进行了分析表征。结果表明:对羟基苯甲酸稀土配合物呈球状,粒径在100nm左右;配合物具有良好的热稳定性。配合物的荧光发射峰分别与稀土铕5D0→7FJ(J=0,1,2,4)的跃迁相对应,最强发射峰位于616.3nm处。将制得的配合物与聚丙烯树脂进行熔融纺丝,制得稀土荧光纤维。测试结果表明:纤维具有优异的荧光性能,最强发射峰位于618nm处,是Eu3+的特征红色发射谱带。     

稀土Eu~(3+)与牛血清白蛋白配合物合成及其分子光谱表征

研究了稀土 Eu3 +与牛血清白蛋白 ( BSA)的固体配合物合成方法 ,产物经傅里叶红外光谱分析表明 :Eu3 + 与牛血清白蛋白羧基的氧和胺基或酰胺基的氮形成强烈配位的配合物。在模拟生理条件下研究了 Eu3 + 与 BSA的结合性质。荧光光谱表明 :Eu3 + 与 BSA形成 2 .75∶ 1的配合物 ,表观配位常数为 lg K=1 2 .2 6     

超长余辉蓄能发光涂料的制备

通过选用透明度高、太阳能吸收率高的丙烯酸树脂和高亮度、长余辉时间的镝和铕稀土离子共掺杂的稀土硅酸盐光致发光粉末材料aCaO·bZnO·cBaO·dMgO·nSiO2:Eu,Dy,制备出了具有较强的蓄光能力和较长发光时间的夜光涂料,并论述了其制备方法和特性。     

Dy and Eu activated Ca3B2O6 phosphors for near ultraviolet‐based light‐emitting diodes

The Dy‐ and Eu‐activated Ca₃B₂O₆ phosphors were synthesized by a high‐temperature solid‐state reaction technique and their structural and luminescent properties were investigated. The phosphors are characterized by X‐ray diffraction, photoluminescence spectra, and Commission International de I'Eclairage (CIE) chromaticity coordinates. It is found that the charge compensator Na⁺ plays an important role in modifying the emission spectral profiles of Dy and Eu ions in the phosphors. The ratio of the emission located at the yellow wavelength portion to that located at the blue wavelength region of the Dy³⁺ ions can be apparently tuned by changing the Na⁺ content. The luminescence intensity of the phosphors can be enhanced with introducing Na⁺ ions as well. The emission colors of Dy/Eu codoped phosphors change from blue to white and successfully acquire the superior white light emission (x = 0.330, y = 0.329) by appropriately tuning the Na⁺/Dy³⁺ content and the excitation wavelength. The energy transfer process from Eu²⁺ to Dy³⁺ and Eu³⁺ occurs in the Dy/Eu codoped phosphors, providing a further approach to modify the emission spectral profile of the examined phosphors. The phosphors presented here have promising applications in the fields of light‐emitting diodes.     

Enhancement of the luminescent intensity of the novel system containing Eu3+‐β‐diketonate complex doped in the epoxy resin

Photoluminescent properties of the europium tris(thenoyltrifluoroacetonate) dihydrate [Eu(TTA)₃(H₂O)₂] incorporated in epoxy resin in the solid state are reported. The polymeric Eu³⁺ complex and the precursor compound were characterized by elemental analysis, thermogravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy, nuclear magnetic resonance (NMR), and electronic spectroscopy. Due to efficient energy transfer from the polymer to the rare earth ion, the polymer phosphorescence intensity was observed to decrease with an increase of the Eu³⁺ ion concentration. High values of the Ω₂ intensity parameter were obtained, reflecting the hypersensitive character of the ⁵D₀ → ⁷F₂ transition and indicating that the Eu³⁺ ions are in a highly polarizable chemical environment. This is consistent with systems containing epoxy resin that generally show a higher value for the Ω₄ parameter as a consequence of the difference in the basicity of the oxygen donor from the polymer. Lifetime measurement (τ = 0.442 ms) suggests that the Eu³⁺ luminescence has a higher efficiency than in the case of hydrated compound (τ = 0.260 ms). The emission quantum efficiency shows higher luminescence for the polymer containing 1% of Eu³⁺‐β‐diketonate complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2716–2726, 2002     

Synthesis and photoluminescent properties of four novel trinuclear europium complexes based on two tris-β-diketones ligands

Four novel trinuclear europium complexes with two tris-β-diketones ligands have been synthesized, and the chemical structures of ligands and complexes were characterized by FT-IR, UV-vis, ¹H NMR, ¹³C NMR, XRD, ESI-MS, and element analysis. The potoluminescent properties of trinuclear complexes in solid and THF solution were investigated. All trinuclear complexes exhibited strong relative luminescent intensity and long luminescent lifetime. Meanwhile, the results of lifetime decay curves indicated that only one chemical environment existed around the europium ion. The intrinsic luminescent quantum yields (Φ_LN) and experimental intensity parameters of trinuclear complexes were obtained based on the emission spectra and luminescent lifetime of ⁵D₀ excited state for europium ion. All trinuclear europium complexes exhibited relative high intrinsic luminescent yield and intensity parameters. Especially, due to the contribution of addition two europium lumophors in trinuclear europium complexes, the trinuclear complexes containing TTA exhibited much longer lifetime and higher intrinsic quantum yield than mononuclear europium complex Eu(TTA)₃phen.