SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION

In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.

Direct Determination of Rare Earth Impurities in High Purity Europium Oxide by ICP-MS

A novel inductively coupled plasma mass spectrometry method for direct determination of trace rare earth impurities in high purity europium oxide (Eu_2O_3) was developed. The spectral interference,matrix effect,instrument parameters fluctuation were investigated and the optimized experimental conditions were established. Under the selected conditions,the detection limits of the method are 3～7 ng·L (-1),the RSD is varied between 2.1%～8.4%,and the percentage recovery is ranged from 90% to 113% for the analytes. The solid detection limit for gross amount of 13 rare earth impurities is 0.19 μg·g (-1) when the matrix (Eu) concentration of 0.1 mg·ml (-1) was chosen. Compared with the reported methods in the literature,this method has several attractive features: simple,small sample amount required,no internal standard and matrix matching requirements.

Adsorption of Rare Earth Ion La(Ⅲ) on Yunnan Bowl Tea Surface from Aqueous Solution

The adsorption characteristics of rare earth ion La(Ⅲ) on Yunnan bowl tea surface from aqueous solution and effects of various surfactants on the adsorption were studied. It was found that Yunnan bowl tea can adsorb strongly La(Ⅲ) and pH may affect drastically the adsorption amount of La(Ⅲ). The adsorption law of La(Ⅲ) on Yunnan bowl tea surface follows the Langmuir equation. The maximum adsorption amount of La(Ⅲ) can reach 15 mg·g (-1). A comprehensive adsorption model is suggested according to the experimental results.

Local vibration around rare earth ions in alkaline earth fluorosilicate transparent glass and glass ceramics using Eu^(3+) probe

By heat treating the alkaline earth fluorosilicate glass, transparent glass ceramics containing alkaline earth fluoride nanocrystallites were prepared. The luminescence spectra and phonon sideband associated with the Eu^3＋：^5D2→^7F0 in glass and glass ceramics were investigated to analyze the local environment around Eu^3＋. Judd-Ofelt parameters were also calculated from emission spectra, which indicated that the Eu^3＋ ions entered the precipitated CaF2, SrF2, and BaF2 nanocrystallites. Heat treating could not pledge Eu^3＋ ions to coordinate with F^- in the precipitated MgF2 nanocrystallites, owing to the smaller radius of Mg^2＋ than that of Eu^3＋.

Progresses in electroluminescence based on europium(Ⅲ) complexes

The research on electroluminescence based on europium（III） complexes has come to an important phase. This article reviewed the progresses in photoluminescence and electrohiminescence of Eu（III） complexes in recent years from the views of the design of Eu（III） complexes and optimization of device structures, and discussed some important factors influencing electroluminescence performance. The problems existing in the practical application such as the volatility and thermal stability of Eu（III） complexes in this area were discussed, and the possible corresponding solutions were briefly prospected.

Crystal Structure and Fluorescent Study of a Binuclear Europium(Ⅲ) Complex

A novel binuclear Eu（Ⅲ） complex [Eu2（dpa dioxide）2（NO3）4（bpdioxide）-（EtOH）] （dpa dioxide = di-2-pyridylamine N,N＇-dioxide, bpdioxide = 2,2＇-bipyridine N,N＇-dioxide） has been synthesized and it exhibits strong and sharp fluorescent emission at 614 nm under UV radiation of 245 nm at room temperature. X-ray structural determination indicates two independent Eu（Ⅲ） ions in the structure with different EuO8N and EuOgN environments. The compound crystallizes in the triclinic system, space group P1, with a = 10.8089（7）, b = 11.4670（8）, c = 17.1440（12） A, α = 92.834（2）, β = 93.854（3）, γ = 95.433（2）°, Z = 2, Dc = 1.876 g/cm3, V= 2107.3（2） A3, F（000） = 1168.0, the final R = 0.032 and wR = 0.086 for 6331 observed reflections with I 〉 2σ（I）.

Synthesis and Characteristic Study on Complexes of Europium(Ⅲ) and Maleic Acid Doped with Non-Fluorescent Ions

Complex of europium （Ⅲ） with maleic acid, and binuclear complexes of europium（Ⅲ）with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8：2. The order of Eu^3＋ fluorescence strengthened by three doped rare earths was Gd^3＋ 〉La^3＋ 〉Y^3＋

Photoluminescence and electrochemiluminescence studies of chosen rare earths systems

Eu（Ⅲ） complexes with chosen Keggin polyoxomatalates, POM, containing organic counter cations （tetrabutylarnmonium, tetrabutylphosphonium, triphenylethylphosphonium）, were synthesized, and their photophysical properties were studied. The synthesized complexes had the general formula of XnH5-n[EuSiW11O39], formulated based on the results of elemental and thermogravimetric analysis and FTIR spectroscopy. The photophysical properties of the obtained compounds were investigated using photoluminescence and electrochemiluminescence, ECL, methods in solutions and solids. The most intense luminescence of Eu（Ⅲ） was observed for the complexes with tetrabutylarnmonium cations. After the addition of phenanthroline to the XnH5-n[EuSiW11O39] solutions, a large increase in the Eu（Ⅲ） luminescence intensity and a lengthening of its luminescence lifetime were observed as a result of the formation of ternary complexes. Attempts to apply ECL as a method of light emission by generating species capable of forming excited states in Ln/POMs, i.e., Tb（Ⅲ） and Eu（Ⅲ） in the Na9EuW10O36 and Na9TbW10O36 complexes, were made. The influence of the POM complexes on the ECL was also tested using the Tb/EDDHA （EDDA=ethylenediamine di（o-hydroxyphenylacetic acid）） complex, which is effective in generating ECL.

Preparation, Photo and Electroluminescence Properties of Novel Rare Earth Aromatic Carboxylates

Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb 3+ and Eu 3+ aromatic carboxylates and lifetimes were investigated, which indicated that these rare earth complexes have high quantum efficiency. Because of their excellent solubility, polymer-doping rare earth carboxylates were fabricated as thin films by spin-coating method and their luminescence properties were studied. Some rare earth organic light-emitting diodes were successfully fabricated which performed high pure color. The maximum luminance of the device of ITO/PVK/PVK∶Tb(AS) 3Phen∶PBD/PBD/Al is 32 cd·m -2 at 28 V.

Synthesis,Characterization,and Luminescence Properties of a Multi-benzoic Acid Rare Earth Complex Applied to Fluorescence Nanometer and Micrometer Fiber

The design and synthesis of a novel multi-benzoic acid ligand and the luminescence properties of the rare earth complex with the ligand and Eu3 +were focused on. The composition and structure of ligand and complex were characterized by Fourier transform infrared( FT-IR) spectroscopy,1H nuclear magnetic resonance(1H NMR) techniques, and element analysis. The luminescent properties,heat resistant performance,morphology and distribution in fibers of the complex were also measured. The fluorescent spectra indicate that as-synthesized complex owns excellent luminescent properties. The maximum relative fluorescence intensity of the complex is more than 7 000. The thermo-gravimetric analysis( TGA) results confirm that the initial degradation temperature of as-synthesized complex is at 413 ℃. Transmission electron microscope( TEM) and field-emission scanning electron microscope( FESEM) photos show that the particle size of assynthesized complex is 50-60 nm,and can be uniformly distributed in fiber. Based on these results, it can be concluded that the synthesized complex has excellent luminescent properties, good thermal stability,and extensively application prospect.

Preparation and Characteristics of Rare Earth Loaded Titanium Dioxide

Composite oxide catalysts Eu/TiO 2, Ce/TiO 2, Y/TiO 2 (RE/TiO 2) were prep ared by impregnation method and characterized by means of UV-Vis spectroscopy, TEM and BET. The results indicate that the size of TiO 2 has different effect o n the modification effic iency. The catalytic activity of micron scale TiO 2 increases by 136% and 59% o w ing to the addition of Y and Ce, respectively, while the catalytic activity of n anoscale TiO 2 decreases due to the doping of Y and Ce.

Synthesis and Photoluminescence of Three Europium (Ⅲ) Ternary Complexes with New Secondary Ligands of Different Structure

Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium (Ⅲ) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium (Ⅲ) ternary complexes were confirmed by elementary analysis, IR and (()~1H-NMR) spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(Ⅲ) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(Ⅲ) complexes are good red-emitiing materials for potential application in fabrication of organic electroluminescence devices.

Synthesis, Structure and Photoluminescent Properties of A Novel Oxadiazole-Functionalized Europium(Ⅲ) Complex

A new oxadiazole-functionalized ligand, 2-benzamide-5-phenyl-[ 1,3,4 ] oxadiazole （HL1） was synthesized. With it as the first ligand, 2-Phenyl-imidazo[4,5-f] 1, 10-phenanthroline （L2） as the second ligand, a novel europium complex [Eu（L1）3L2] was prepared and characterized by X-ray structure analysis and photoluminescent spectrum. The complex crystallizes in triclinic with space group of Pi. The crystal data are as follows： a = 1.4892（3） nm, b = 1.6639 （3） nm, c=1.7258（4） nm, α =9.290（3） nm, β=11.014（3） nm, γ=11.554（3） nm, V=3520.7（12） nm^3, Z= 2, M = 1244, Dc = 1.292 g·cm^-3, μ = 1.381 mm^-1 and F（000） = 1389. The final R and wR values are 0. 0680 and 0. 1557 for 6607 [ I 〉 2σ （I）] unique reflections. In the complex, each Eu（ Ⅲ ） ion is eight-coordinated by three carbonyl oxygen atoms and three oxadiazole nitrogen atoms from L1, two nitrogen atoms from the L2, forming a distorted square antiprism coordination geometry. The complex shows intense red emission typical of Eu^3＋ ion under UV excitation, both ligands L1 and L2 exhibit strong antenna effects.

Syntheses aod Crystal Structures of Rare Earth Complexes with Adamantanecarboxylic Acid, [LnL_3(HL)(H_2O)]_2·2EtOH·2H_2O (Ln=Nd (1), La (2))

The title complexes （LnL3 （HL） （H2O） ]2· 2EtOH·2H2O （Ln= Nd （1）, La （2）, HL=adamantanecarboxylic acid） were prepared and determined by single-crystal X-ray diffraction. Both complexes crystallize in triclinic system with space group P 1^-, cell parameters are： complex （1） a = 1.0556（2） nm, b =1.4913（3） nm, c = 1.4920（3） nm, a = 106.26 （3）°, β=93.51（3）°, γ=97.23（3）°, V=2.2253 （5） nm^3, Dcal=1.409 g · cm^-3, Z = I , F （ 000 ） = 990, μ（Mo Kα） = 1. 225 mm^-1, M, = 1884.50; complex （2） a = 1.0453（2） nm, b = 1.4971（3）nm, c = 1.5052（3） nm, α = 106.07（3）°, β =93.58 （3）°, γ=97.56（3）°, V=2.2391（5）nm^3, Dcal= 1.397 g·cm^-3, Z = 1, F（000） =984, μ（Mo Kα） = 1.015 mm^-1, Mr= 1877.88. The final R and wR are 0. 0396 and 0. 1062 for 8589 （1 ≥ 2σ （I）） observed reflections for complex （1）, 0.0505 and 0. 1344 for 8417 （ 1 ≥ 2σ （1） ） observed reflections for complex （2）, respectively. The crystals are consisted of a binuelear molecule. The coordination geometry of the Ln（ Ⅲ ） ion can be described as trieapped trigonal prism.

Determination of Light Rare Earths by a Spectrophoto-metry Based on the Linear Combination of Multiwavelength Data

The present paper proposes a new method of spectrophotometry based on linear combination of multiwavelength data by means of selecting a set of properly weighted coefficients and combination methods. It is clear that the weighted combination absorbance attained is only in direct proportion to the concentration of the analysed component and independent of coexisting interferents.The accuracy of the analytical results is improved greatly for the analysis of light rare earths with the coexistence of heavy rare earths.The analyti- cal error from the reagent blank and co-coloration of light and heavy rare earths have also been overcome. The greatly improved linearity and additivity of absorbance are obtained.

Fractionation characteristics of rare earth elements(REEs) linked with secondary Fe, Mn, and Al minerals in soils

Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs(La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs(LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs(HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs.The substantial fractions of REEs in soils extracted byoxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile(10 %–30 %), which were similar to the mass fraction of Fe(10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.

高度支化聚芳酰胺/稀土铕(Ⅲ)发光材料的合成及表征

通过溶液聚合的方法以氮三乙酸(NTA),4,4′-二氨基二苯醚(ODA)为原料合成了高度支化聚芳酰胺(PNOA),并以PNOA为配体与EuCl3配位制备出Eu/PNOA高分子发光材料。采用红外光谱分析了PNOA和Eu/PNOA的结构,用热重(TG)分析了Eu/PNOA的热稳定性,用紫外及荧光光谱法表征了它们的光学性能。结果表明,PNOA与稀土离子Eu3+发生了配位作用,Eu/PNOA在被350nm的紫外光激发后发出616nm的红色荧光,是一种具有潜力的高分子功能材料。

新的β-二酮及其Eu(Ⅲ)三元配合物的合成与发光研究

合成了一种新的β 二酮,4 甲氧基联苯甲酰三氟丙酮(1 (4′ meothoxybiphenyl 4yl ) 4,4,4, trifluoro butane 1,3 dione,MBPTFA),以元素分析和1H NMR谱确定了其组成;进而以MBPTFA作第一配体和邻菲罗啉(1,10 phenanthroline,Phen)为第二配体,与EuCl3反应,合成了一种三元配合,Eu(MBPTFA)3Phen。用元素分析、红外、紫外 可见吸收光谱和荧光光谱进行了表征。荧光分析结果表明:配体本身是一种良好的蓝色发光材料;配合物中的有机配体能够有效地的把吸收的能量传递给中心Eu3+离子,强烈敏化Eu3+发光,且发射谱线很窄,主发射峰为Eu3+的5D0-7F2发射。这对寻找新型稀土配合物发光材料和制备有机电郅发光器件具有一定的价值。

铕(Ⅲ)-4-乙烯基吡啶共聚物稀土高分子配合物的合成及其光物理行为的研究

以 4 乙烯基吡啶 (4VP)与甲基丙烯酸甲酯 (MMA)的共聚物为配体 ,并以邻菲洛啉 (Phen)及 2 ,2′ 联吡啶 (Bipy)小分子配体协同反应 ,与Eu(Ⅲ )配位 ,合成了稀土高分子配合物 ;通过FTIR表征了配合物的结构 ;通过紫外光谱与荧光光谱的测定 ,较充分地研究了稀土高分子配合物光致发光的光物理过程。实验结果表明 ,4 乙烯基吡啶共聚物通过吡啶环上的氮原子与稀土离子可直接配位 ;小分子配体的协同配位 ,可使稀土离子配位数趋于满足 ,且由于小分子配体能有效地加强能量吸收及分子内的能量传递 ,大大增强了配合物的荧光强度。

含有不同结构第二配体的铕(Ⅲ)三元有机配合物的合成与发光

合成了3种新的1,10 菲罗啉的衍生物:二吡啶[3,2 f:2′,3′ h]喹喔啉(DPQN),咪唑并[5,6 f]邻菲罗啉(IP)和苯基咪唑并[5,6 f]邻菲罗啉(PIP),以它们作为第二配体,并以二苯甲酰甲烷(DBM)为第一配体,合成了3种新的铕(Ⅲ)三元有机配合物。通过元素分析、红外光谱、1H 核磁共振光谱确定了它们的组成,研究了3种配合物的热稳定性、成膜性能和光致发光性能(发光强度,荧光量子效率和寿命),并初步从理论上探讨了含有不同结构的第二配体对铕(Ⅲ)配合物发光的影响,为筛选有机电致发光新材料提供了认识基础。