Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO_3 Ceramics

Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO3 structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba （ Ti1 -x Cex ） O3 （x = 0. 05, 0. 10 ） （CBT） and （ Ba1-y Euy ） Ti1-x/8O3 （ y = 0. 05, 0. 10） （EBT）. Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO3 ceramics were discussed. The CBT ceramics exhibit a pseudocubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu2Ti2O7 phase. The Curie peak of BaTiO3 shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms（ Eu≤5% ）, respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution（ 1 μm）, a lower porosity and a higher density（5.85 g/cm^3）, more stable dielectric-temperature dependence（ ε′= 1600-1800 at t 〈 50℃ ） and a lower dissipation factor（ 〈 0. 05 ）. The stability of dielectric constant with frequency in BaTiO3 can extend to 107 Hz due to Ce and Eu doping.

Effects of Lanthanum and Europium on Rooting of Plantlet Eriobotrya Japonica Lindl. in vitro

The effect of La 3+ and Eu 3+ on the rooting of Eriobotrya japonica Lindl. plantlet in vitro was studied with adding La 3+ and Eu 3+ to the rooted medium. The rooting rate, the number of root and the length of root were studied after transplanting 20 d. The activity of peroxidase, nitrate reductase and fresh weight of roots were determined after transplanting 44 d. The results show that the optimum concentration range of La 3+ (1.0～3.0 μmol·L -1), Eu 3+ (2.0～3.0 μmol·L -1) in the rooted medium can increase the rooting rate and the fresh weight of roots, and promote the length of root and raise the activities of peroxidase and nitrate reductase significantly. La 3+ has more effect in improving the rooting rate, root length and the activities of peroxidase and less effect in promoting root fresh weight and the activities of nitrate reductase than Eu 3+.

Time-resolved fluoroimmunoassay of zearalenone in cereals with a europium chelate as label

A competitive indirect time-resolved fluoroimmunoassay(TRFIA) was developed for detection of zearalenone(ZEN) in cereals,in which ZEN conjugated to bovine serum albumin(BSA) is used as solid-phase antigen.A competitive indirect TRFIA was conducted by simultaneously incubating ZEN in standard or extracted samples with anti-ZEN monoclonal antibody over ZEN-BSA coated plates,and then determining the bound ZEN monoclonal antibody with goat anti-mouse europium conjugate.Samples were extracted with methanol/water...

Synthesis,Characterization and Fluorescence Properties of Europium,Terbium Complexes with Biphenyl-4-Carboxylic Acid and o-Phenanthroline

Two series of solid complexes of europium and terbium with biphenyl 4-carboxylic acid and phen were synthesized and characterized in this report. Their elemental analysis, molar conductivities and TG-DTA studies indicate that the complexes have the composition of Eu(phen)L3·1/2H2O, Eu0.5RE0.5(phen)L3·1/2H2O; Tb(phen)L3·H2O and Tb0.5RE0.5(Phen)L3·1/2H2O. (RE=Y3+, La3+ and Gd3+; L=biphenyl 4-carboxylic acid; phen=o-Phenanthroline). The studies of their IR, UV 1H NMR and molar conductivities demonstrate that biphenyl 4-carboylic acid is bounded with RE(Ⅲ) ion. Rare earth ions coordinate with two nitrogen atoms of phen molecules directly in these rare earth complexes. The fluorescence spectra and fluorescence lifetimes of the rare earth complexes show that the fluorescent intensity and lifetime of a series of europium complexes are longer than those of the series of terbium complexes as having the some ligands. There are better fluorescent intensity and lifetime of hetero-nuclear rare earth complexes than homo-nuclear rare earth complexes for europium complexes. The fluorescence emission intensity of Eu3+ is raised by inert fluorescent rare earth ions (Y3+, Gd3+ and La3+), but in Tb3+ hetero-nuclear rare earth complexes the intensity of Tb3+ ions are quenched by the inert fluorescent rare earth ions.

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 Properties of Europium m-Chlorobenzoate Complex with 1,10-Phenanthroline

A europium m-chlorobenzoate complex with 1,10-phenanthroline [Eu(m-ClBA)_3(phen)]_2 single crystal, where m-ClBA=m-chlorobenzoate and phen=1,10- phenanthroline,was prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic, space group P1- with a=1.10138(8)nm, b=(1.18606(9) nm,) c=1.32516(10) nm, α=112.5390(10)°, β=92.1700(10)°, γ=101.6220(10)°,(C_(66))H_(40)N_4O_(12)Cl_6Eu_2, M_r=1597.64, V=1.5533(2) nm^3, Z=1, D_c=1.708 g·cm^(-3), μ(Mo Kα)=2.325 mm^(-1), (F(000))= 788, the final R=0.0424 and wR=0.0899 for 6856 independent reflections with R_(int)=(0.0776.)The crystal consists of binuclear molecules of the title compound. Each Eu^(3+) ion is nine-coordinated to one 1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups. The carboxylate groups are bonded to the europium ion in three modes: the chelating bidentate, the bridging bidentate and bridging-chelating thridentate. Excitation and luminescence data observed at room temperature show that the title complex (emits) very intensive red fluorescence under ultraviolet light. The results of thermal analysis indicate that the complex [Eu(m-ClBA)_3(phen)]_2 is quite stable to heat.

Synthesis,crystal structure and fluorescence of a new europium complex with 2-bromobenzoate and 2,2'-bipyridine

A new complex of {[Eu2(2-BrBA)6(2,2’-bpy)2]2·CH3CH2OH·H2O} (2-BrBA=2-bromobenzoate; 2,2’-bpy=2,2’-bipyridine) was prepared by solvent method and characterized with X-ray single-crystal diffraction, IR spectroscopy, UV spectroscopy, and fluorescence spectroscopy. The complex crystallized in triclinic crystal system, Pī space group, with a=1.17196(4) nm, b=2.36142(9) nm, c=2.59151(9) nm, α=113.266(2)°, β=101.100(2)°, and γ=94.400(2)°. Two independent dinuclear molecules were contained in the asymmetric unit. The two molecules were similar to each other. Each Eu(Ⅲ) ion was nine-coordinated with seven oxygen atoms from five 2-BrBA ligands and two nitrogen atoms from 2,2’-bpy molecule. The carboxylate groups acted as bidentate-chelating, bidentate-bridging and chelating-bridging coordination modes. The complex adopted a distorted monocapped square-antiprism coordination geometry. Five peaks at 579, 591, 613, 652, and 697 nm appeared in the fluorescence spectrum, corresponding to 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transition emissions of the Eu(Ⅲ) ion, respectively.

Synthesis and Photoluminescence of New Europium Complex Eu(DBM)_3(DPPZ) with Dipyridophenazine Ligand

Dipyrido [3, 2-a:2,3-c] phenazine moiety has been introduced as neutral ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent intensity and good solubility was designed and synthesized for the first time. Its photoluminescence and UV properties were examined. The experimental results showed that this new Eu-complex could be used as red electroluminescent materials.

Hydrothermal Synthesis and Characterization of Europium-doped Barium Titanate Nanocrystallites

Barium titanate nanocrystallites were synthesized by a hydrothermal technique from barium chloride and tetrabutyl titanate. Single-crystalline cubic perovskite Ba TiO_3 consisting of spherical particles with diameters ranging from 10 to 30 nm was easily achieved by this route. In order to study the influence of the synthesis process on the morphology and the optical properties, barium titanate was also prepared by a solid-state reaction. In this case, only the tetragonal phase which crystallizes above 900 was observed. High-temperature X-ray diffraction measurements were performed to investigate the crystallization temperatures as well as the particle sizes via the Scherrer formula. The lattice vibrations were evidenced by infrared spectroscopy. Eu^(3+)was used as a structural probe, and the luminescence properties recorded from Ba TiO_3 :Eu^(3+)and elaborated by a solid-state reaction and hydrothermal process were compared. The reddish emission of the europium is increased by the nanometric particles.

Coating Carbon Nanotubes with Europium Oxide

Carbon nanotubes (CNTS) coating with europium oxide by a simple method is reported in this letter for the first time. The CNTS were refluxed in a solution of nitric acid containing europium nitrate, and the pH value was subsequently ajusted with ammonia solution. At last, the mixture was filtered and annealed. The TEM micrograph showed that the CNTS were covered with a uniform thin layer with thickness of about 15 nm. The XRD results revealed that the CNTS were coated with europium oxide.

Synthesis,Fluorescence and Magnetic Properties of a New Europium(Ⅲ)Complex Eu(C14H9O3)2(C12H8N2)2(NO3)

A new europium(III)complex Eu(CHO)(CHN)(NO)has been synthesized with 2-benzoylbenzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P2/c,a=9.6733(6),b=22.9521(14),c=19.7701(12)?,β=94.9800(10)o,V=4372.8(5)?~3,D=1.557 g/cm~3,Z=4,μ(Mo Kα)=1.501 mm,F(000)=2064,the final R=0.0214 and w R=0.0510.The Eu(III)ion is coordinated by ten atoms to give a bicapped square antiprism coordination geometry.The complex shows two intense fluorescence emission bands arising from the transitions of Eu:~5D→~7F(594 nm)and ~5D→~7F(618 nm).In addition,its XT decreases from 1.29767 cm~3?mol?K at 300 K to 0.01531 cm~3?mol?K at 2 K.

Rapid europium-sensitized fluorescent determination of ulifloxacin,the active metabolite of prulifloxacin,in human serum and urine

A new fluorescent method was developed based on the ulifloxacin-europium（Ⅲ）-sodium dodecylbenzene sulfonate system for the determination of ulifloxacin,the active metabolite of prulifloxacin.Sodium dodecylbenzene sulfonate formed a ternary complex with ulifloxacin-europium（Ⅲ）and significantly enhanced the characteristic fluorescence of europium（Ⅲ）.The enhanced fluorescence intensity showed a good linear relationship with the concentration of ulifloxacin in the range of 5.0×10^-8-2.0×10^-6M with a detection limit of 2.0×10^-10 M（3σ）.This method is rapid and sensitive,and has been successfully applied to the determination of ulifloxacin in human urine and serum samples.

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＋

Crystal Structure and Luminescence of 1,10-Phenanthroline-tris(4-methoxybenzoato)Europium

1,10 Phenanthroline tris(4 methoxybenzoate)europium, Eu( p MOBA) 3phen(where p MOBA= p methoxybenzoate and phen=1,10 phenanthroline) has been obtained in the ethanol solution. The crystal consists of binuclear molecules of the title compound. In the binuclear molecule each Eu 3+ ion is coordinated not only by four oxygen atoms from the bridging carboxylates, but also by two oxygen atoms of a bidentate carboxyl group and two nitrogen atoms of a phen chelating ligand, giving coordination number of eight. Eu O distances range from 0 2336(3) to 0 2483(3) nm. The average Eu N distance is 0 2624(4) nm. Luminescence data indicate that one Eu 3+ ion site is in low symmetry in the complex.

Red Electroluminescence and Photoluminescence from Novel Binuclear Europium Complex with Squaric Acid Ligand

A novel binuclear europium P-diketone complex with squaric acid ligand was synthesized for the first time. Its structure was elucidated by IR, UV, and Elemental Analysis. Red light emitting diode (LED) was fabricated by using the novel europium complex as an emitting layer, tris(8-quinolinolate) aluminum (III) (Alq(3)) as an electron-transporting layer, N, N'-diphenyl-N, N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole-transporting layer. A cell structure of indium-tin-oxide/TPD/Eu-complex/Alq(3)/Mg: Ag was employed. Red electroluminescence was observed at room temperature with dc bias voltage of 2 V in this cell. 2 Red emission peaks at about 613 nm with maximum luminance of over 106 cd/m(2). Compared with the EL luminance from those europium complexes reported before, one from the Eu-complex is best in the same cells.

Synthesis and Fluorescent, Magnetic and Thermal Stability Properties of a New Europium（Ⅲ） Complex Eu2(C15H11O3)6(C12H8N2)2

A new europium(III)complex Eu2(C15H11O3)6(C12H8N2)2 has been synthesized with 2-(4-Methylbenzoyl)benzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P21/n,a=15.1238(5),b=13.5928(4),c=22.9840(7)?,β=104.132(3) ,V=4582.0(2)?3,Dc=1.522 g/cm3,Z=4,μ(MoKα)=1.433 mm-1,F(000)=2128,the final R=0.0447 and wR=0.0826.The Eu(III)ion is coordinated by eight atoms to give a distorted square antiprism coordination geometry.The complex shows two intense fluorescence emission bands arising from the transitions of Eu3+:5D0→7F1(594 nm)and 5D0→7F2(617 nm).The complex is an antiferromagnetism system in the range of 150~300 K.Also reported in the paper is the thermal stability property of the title complex.

The preparation and fluorescence properties of europium nanoparticles

A new structured metallic nanomaterial of europium nanoparticle was prepared using tannic acid as the reductive agent, and nanoeuropium protein conjugates were synthesized by the method of lipoic acid modification on the surface of nanoparticle, which opens a new field of application of lanthanides in nanotechniques. Their properties were also characterized by UV-vis absorption spectroscopy, transmission electron microscopy （TEM）, and fluorescence spectroscopy. The europium nanoparticle and its protein conjugates solution were stable and water-soluble. The fluorescence intensity of the composite europium nanoparticles was significantly increased in the presence of trace protein, and was linear proportional to the concentration of proteins under optimum conditions. According to this, a fluorimetric method for the determination of nrotein was develooed in this paper.

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 photovoltaic properties of new europium complex Eu(DBM)3(CPyBM)

A new europium（Ⅲ） complex, tris（dibertzoylmethanate）{ 1-[9-hexyl-9-carbazole]-2-（2-pyridyl）-bertzimidazole}europium（Ⅲ） [Eu（DBM）a（CPyBM）] was synthesized and used as an electron-acceptor and electron-transport layer in organic photovoltaic （PV） device. Power conversion efficiency achieved from the device was 1.04% under illumination with 365 nm UV light at 1.6 mW/cm^2. Compared with the previous reported devices based on Eu（Ⅲ） complexes, the PV performances were improved. The working mechanism of the organic PV device was discussed.

Synthesis and Fluorescence Properties of Europium, Terbium Doped Zn^(2+), Cd^(2+) and Cr^(3+) Complexes

Europium and terbium complexes with strong fluorescence intensity and long fluorescence lifetime were prepared. By replacing half of the europium or terbium ion with M （M = Zn^2＋, Cd^2＋, and Cr^3＋） using the doped method, and then incorporating it with 18-crown-6 ether and terephthalic acid, six heteronuclear samples EuZnLL＇Cl3·3H2O（1）, EuCdLL2＇Cl3·5H2O（2）, EuCrLL＇Cl4· 4H2O（3）, TbZnLL＇Cl3·4H2O（4）, TbCdLL＇2Cl3·4H2O（5）, and TbCrLL＇2Cl4 ·4H2O（6） （L = terephthalic acid, L＇= 18-Crown-6 ether） were obtained. The elemental analysis, molar conductivities, rare earth complexometry, Fourier Transform Infrared Spectroscopy （FT-IR）, ultraviolet （UV）, TGA, fluorescence intensity, and fluorescence lifetime of the samples were measured. The results showed that there were good luminescence properties for heteronuclear complexes （1）, （2）, （4）, and （5）, which were even stronger than those of the homonuclear complexes Eu2LL＇2Cl4·4H2O and Tb2LL＇2Cl4 ·4H2O, but the luminescence properties of EuCrLL＇Cl4·4H2O, TbCrLL＇Cl4·4H2O were very weak. A possible luminescence mechanism was suggested by the organic-inorganic doped mechanism and the law of intramolecular energy transfer.