Europium Chloride Research Articles

Novel class of functionalized ionic liquids with grafted CMPO-moieties for actinides and rare-earth elements recovery

The general approach to a novel class of functionalized ionic liquids 4-6 bearing grafted diphenylcarbamoylmethylphosphine oxide complexing groups in the cation has been elaborated. The synthetic route comprises the preparation of the intermediate (diphenylphosphorylmethylcarbamoyl)propylimidazole 3, followed by sequential quaternization by alkyl halides (chlorides or bromides) and anionic exchange in the case of ionic liquids bearing the hexafluorophosphate anion. The structures of two ionic liquids were confirmed by X-ray analysis, revealing the strong intramolecular hydrogen bond formed by the acidic protons of the heterocycle and oxygen atom either of the P=O or C=O group, depending on the anion nature. In neutral media, these ionic ligands form complexes ML(2) with europium chloride or europium nitrate via an O,O-bidentate mode similar to known neutral CMPO compounds. The solid phase extractants prepared by immobilization of these FILs on solid matrixes possess sorption activity towards actinides and rare-earth elements in nitric acid solutions.

Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine_coordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

Arc discharge ion source for europium and other refractory metals implantation

The best method for the impurity doping to the host material is the ion implantation. Due to high melting point of the rare earth standard metal ion sources are useless. One of the solution is to use chemical compounds of rare earths characterized by low melting point. In this paper we describe the novel design of the ion source suitable for refractory metal (e.g., rare earths) ion implantation. The dependencies of Eu(+) current on cathode and arc currents as well as on hydrogen flow are presented. Europium (III) chloride as the source of the europium atoms was used. Europium ions were produced during collisions of evaporated and decomposed EuCl(3) molecules with fast electrons. The typical current of the europium ion beam extracted from the ion source was 25 microA for the extraction voltage of 25 kV. The ion source works without maintenance breaks for approximately 50 h, which enables high dose implantation. The presented ion source needs neither advanced high power supplies nor high vacuum regime.

Synthesis and characterization Y 2O 3:Eu 3+ nanocrystals prepared via solvothermal refluxing route

Y 2O 3:Eu 3+ nanocrystals were prepared via co-precipitation–solvothermal refluxing–calcination method using three kinds of organic solvents, propylene glycol, 1,3-butanediol and polyethylene glycol and yttrium chloride hexahydrate and europium chloride as starting materials. The Y 2O 3:Eu 3+ nanocrystals with diameter of 20–50 nm prepared by refluxing in polyethylene glycol followed by calcinations at 800–1000 °C exhibited the strongest luminescence at 611 nm under the excitation wavelength of 254 nm than the reference sample prepared via conventional co-precipitation method. The photoluminescence spectra of the samples were recorded at room temperature. The effect of concentration of Eu 3+ (Eu 3+/Y 3+ atomic ratio: 0.01–0.1) on the photoluminescence intensity was also investigated. The samples with the Eu 3+/Y 3+ atomic ratio of 0.07 exhibited the strongest emission at 611 nm and quenching effect was observed above 0.10.

Crystal growth of nanoscaled europium selenide having characteristic crystal shapes

Tetrapod-shaped EuSe nanocrystals were prepared through the thermal reduction of europium chloride an organic selenide complex, n-hexadecylamine, and two additives oleic acid and oleylamine. The obtained EuSe nanoparticles were characterized by X-ray diffraction (XRD). The crystal grain size from the XRD spectrum was estimated to be 50 nm. In contrast, observation of the transmission electron microscope (TEM) gave larger sized EuSe (average size: 200 nm). Anisotropic crystal-growth of EuSe nanocrystals was achieved by addition of a small amount of oleic acid in the crystal growth process.

Multibubble sonoluminescence of europium(III) chloride in heavy water

A weak glow in the region of the Eu3+ photoluminescence spectrum was detected against the background of the continuum of the solvent emission during multibubble sonolysis of air- or argon-saturated EuCl3 solutions (0.1 mol L−1) in heavy water. No characteristic sonoluminescence of the europium ion in aqueous solutions was observed earlier. Possible reasons for the low yield of Eu3+ sonoluminescence compared with other lanthanide ions (Ln3+) are discussed and the influence of europium on the spectrum of the solvent continuum related, in particular, to quenching of the electron-excited sonolysis products H2O* (D2O*) and Eu3+* in electron transfer reactions.

A Novel 3D Europium (III) Coordination Polymer Constructed from 3,5-Pyridinedicarboxylate Acid: Synthesis, Crystal Structure and Emission Spectrum

A novel 3D coordination polymer Eu2(PDC)3(H2O)3 (1) has been synthesized by hydrothermal reaction of europium chloride with 3,5-pyridinedicarboxylate acid (H2PDC) under acidic condition (pH 2–3). Complex 1 is a 3D coordination polymer via 1D infinite chains built by the pyridinium moieties of the PDC2− anions. The thermal analyses and luminescent properties of 1 have also been investigated. A novel 3D coordination polymer Eu2(PDC)3(H2O)3 has been synthesized by hydrothermal reaction of europium chloride with 3,5-pyridinedicarboxylate acid under acidic conditions (pH 2–3). The formation of the title complex demonstrates that pH plays an important role during the synthesis.

Photoinduced electron transfer from higher excited singlet states of tryprophan: 1. Effects of the excitation wavelength, pH, and temperature on quenching of Tryptophan fluorescence by europium(III) ions

Effects of the excitation energy, temperature, and pH on the quantum yield and the Stern-Volmer quenching constant for tryptophan fluorescence quenching by europium(III) chloride were studied. Competition between intracomplex reversible photoinduced electron transfer from tryptophan to Eu(III) ions and the processes of internal conversion and vibrational relaxation of higher excited singlet states S n (n > 1) of tryptophan was revealed.

Dielectric investigations and ac conductivity of polyvinyl alcohol films doped with europium and terbium chloride

Differential scanning calorimetry (DSC) was used to identify the phase transitions of polyvinyl alcohol (PVA) doped with europium chloride (EuCl 3) and terbium chloride (TbCl 3). The dielectric constant and the loss tangent behavior of the investigated samples were studied as a function of temperature in the frequency range 1–100 kHz. The detailed analysis of the results showed that dielectric dispersion consists of both dipolar and interfacial polarization. The temperature coefficient of permittivity (TCP) and the electrical dipole moment ( μ) were calculated. Also, the activation energy for the glass relaxation process from the dielectric loss tangent measurements was calculated. Measurements of the ac conductivity as a function of frequency at different temperatures indicated that the correlated barrier hopping (CBH) model is the most suitable mechanism for the ac conduction behavior. The ac parameters, such as hopping distance ( R, R min), polaron binding energy ( U M) and Coulombic barrier height ( U h) were calculated.

Studies on the synthesis of europium activated yttrium oxide by wet-chemical method

Abstract Europium activated yttrium oxide phosphor powders (Y 2 O 3 :Eu 3+ ) were prepared from yttrium–europium precursors obtained by wet-chemical method. With this purpose in view, precursors were prepared using the reagent simultaneous addition SimAdd technique from yttrium–europium nitrate and chloride as rare-earth supplier and urea, ammonium oxalate, ammonium carbonate and oxalic acid as precipitating agents. Precursors, obtained under controlled concentration, temperature and pH conditions, were fired at 1200 °C in order to generate Y 2 O 3 :Eu 3+ phosphor powders. Yttrium–europium precursors and Y 2 O 3 :Eu 3+ phosphor powders were investigated by FTIR, TGA–DTA, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and photoluminescence spectroscopy (PL) in order to put in evidence the influence of the quality of yttrium–europium precursors obtained by wet-chemical method, using the SimAdd technique on the properties of Y 2 O 3 :Eu 3+ phosphor powders.

Measurement of the Binding of Cholera Toxin to GM1 Gangliosides on Solid Supported Lipid Bilayer Vesicles and Inhibition by Europium (III) Chloride

In this paper the immobilization of small unilamellar DMPC/GM1 lipid vesicles containing a water-soluble bodipy dye is described. The binding of the complete alphabeta toxin expressed by Vibrio cholerae to the attached vesicles was measured using Surface Plasmon Resonance (SPR) and a value of the dissociation constant K d obtained. Further measurements showed that the interaction of both the alphabeta-toxin and the beta-subunit alone resulted in the permeation of the lipid membrane, with release of a fluorophore contained within the vesicle being measured by combined SPR and Surface Plasmon enhanced Fluorescence Spectroscopy (SPFS). The leakage of dye through the membrane, measured by following the change in fluorescence, was fitted to a simple diffusion model. Finally, SPFS measurements of the effect of europium(III) chloride (EuCl 3) showed that cholera toxin binding and subsequent membrane permeation could be blocked by 1 micromol dm (-3) europium chloride. In view of the low oral toxicity of europium chloride, we speculate on the potential pharmaceutical applications of this molecule in the treatment of cholera infection.

Identification and Characterization of Nonchromate Corrosion Inhibitor Synergies Using High-Throughput Methods

Abstract The replacement of chromate corrosion inhibitors will require synergistic combinations of materials that can only be identified and characterized through experimentation at the present time. One approach to accelerate the discovery and characterization of materials is through the use of high-throughput screening (HTS) methods. This paper presents three methods developed for the HTS of corrosion inhibitors and their combinations for the aluminum aerospace alloy, AA2024-T3 (UNS A92024). Rapid assays for corrosion determination included direct current (DC) polarization, surface copper assessment, and fluorometric detection of Al3+. These methods increased experimental throughput by a factor of more than 1,000. Tests were conducted on single and binary combinations of cerium chloride (CeCl3), yttrium chloride (YCl3), lanthanum chloride (LaCl3), europium chloride (EuCl3), gadolinium chloride (GdCl3), neodymium chloride (NdCl3), sodium metatungstate (NaWO4-3WO3), sodium metavanadate (NaVO3), sodium mol...

Europium separation from a middle rare earths concentrate derived from Egyptian black sand monazite

Europium separation from a middle rare earth concentrate has been achieved successfully by using the combined chemical reduction–precipitation technique. The separation method depends on the reduction of europium by metallic zinc to its bivalent oxidation state followed by selective precipitation of the sparingly soluble europium (II) sulphate, while leaving the other rare earth sulphates in solution. This process consists of two steps; the first is reduction, which involves passing europium (III) chloride solution through a column packed with zinc particles. The other step involves the precipitation of the produced europium (II) chloride using a sulphate salt under inert atmosphere. Variables such as column dimensions, acidity, europium concentration in feed solution, contact time, ageing time, and concentration of the precipitating agent, have been evaluated with a pure europium synthetic solution. Based on the obtained results, a separation process was suggested for the separation of europium from a middle rare earth concentrate extracted from an Egyptian beach sand monazite. The result of this working-up is a europium yield of about 91% of the amount employed with a purity of about 97%.

Synthesis, characterization and optical properties ofEu2O3 mesoporous thin films

For the first time, nanocrystallineEu2O3 thin films,exhibiting ∼50% of porous volume, highly accessible mesoporosity, pore diameter of about 10 nm, and thermal stabilityup to 830 °C, were prepared using the evaporation-induced self-assembly (EISA) process from europium(III) chloride and specific polyethylene oxide based copolymer structuring agent.Crystallization of the inorganic network was achieved through a controlled thermaltreatment sequence that was followed by in situ time-resolved SAXS/WAXS analysisinvolving synchrotron radiation. Atomic force microscopy (AFM) and x-ray diffraction(XRD) were used to complete the characterization of the crystallization of the film. Porousstructures were additionally analysed by transmission electron microscopy (TEM), andenvironmental ellipsometry porosimetry (EEP), while the composition of the films wascharacterized by Rutherford back-scattering (RBS). Finally, the luminescence properties ofthese layers were investigated.

Novel fluorescent probe for low density lipoprotein, based on the enhancement of Europium emission band

We report here the observation of the enhancement of Europium-tetracycline complex emission in Low Density Lipoprotein (LDL) solutions. Europium emission band of tetracycline solution containing Europium (III) chloride hexahydrate was tested to obtain effective enhancement in the presence of native LDL and oxidized LDL. Europium emission lifetime in the presence of lipoproteins was measured, resulting in a simple method to measure the lipoproteins quantity in an aqueous solution at physiological pH. This method shows that the complex can be used as a sensor to determine the different states of native and oxidized LDL in biological fluids.

Characterization of the hyperfine interaction in europium-doped yttrium orthosilicate and europium chloride hexahydrate

We present characterization of the hyperfine interaction for the europium in hydrated europium chloride and as a dopant in yttrium orthosilicate. The Zeeman and pseudoquadrupole tensors were determined by measuring the hyperfine splittings while rotating the direction of a weak $(\ensuremath{\sim}300\phantom{\rule{0.3em}{0ex}}\mathrm{G})$ magnetic field. The hyperfine spectra were recorded using Raman-heterodyne spectroscopy, an radio-frequency optical double resonance technique. For both materials magnetic field values were identified where there is no first order Zeeman shift in a europium hyperfine transition. These field insensitive transitions will have application in achieving very long hyperfine coherence times.

The high throughput assessment of aluminium alloy corrosion using fluorometric methods. Part I – Development of a fluorometric method to quantify aluminium ion concentration

This paper examines a new method developed for the rapid assessment of corrosion inhibitors and their combinations for aluminium alloy 2024-T3 (AA2024-T3). Two fluorometric probes, lumogallion and morin, were used to rapidly assess the concentration of aluminium ions in solution through the use of a spectrophotometric plate reader. Fourteen potential inhibitor compounds and other assay constituents were screened for fluoroprobe interference: sodium chromate, sodium metavanadate, cerium chloride, lanthanum chloride, europium chloride, gadolinium chloride, neodymium chloride, yttrium chloride, barium metaborate, sodium metatungstate, potassium phosphate, sodium metasilicate, sodium phosphate, and sodium molybdate. Calibration curves were established for the two probes.

Thermochemistry of europium and dithiocarbamate complex Eu(C5H8NS2)3(C12H8N2)

A solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen⋅H2O) in absolute ethanol. IR spectrum of the complex indicated that Eu3+ in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms from the o-phen. TG-DTG investigation provided the evidence that the title complex was decomposed into EuS.

Kinetics of electrode processes and thermodynamic properties of europium chlorides dissolved in alkali chloride melts

Electroreduction of EuCl 3 in alkali chloride melts (NaCl–KCl, KCl, CsCl) was studied in the temperature range 973–1173 K by different electrochemical methods. The diffusion coefficients ( D ) for Eu(III) and Eu(II) were determined by linear sweep voltammetry, chronopotentiometry and chronoamperometry methods, showing that D decreases with increase of europium oxidation state, while the activation energy for diffusion increases. Decreasing values of D were also obtained when the cation in the second coordination sphere changed from Na to Cs. It was shown that such changes are due to the decreasing counter polarizing effect of cations at increasing cationic radius. The standard rate constants of charge transfer ( k s ) for Eu(III)/Eu(II) redox couple were calculated on the basis of cyclic voltammetry data. It was found that k s increase from NaCl–KCl to CsCl melt and electron transfer for the redox reaction proceeds over outer-sphere cation. The larger values for k s were determined in CsCl melt, because of caesium larger polarizability. The formal standard potentials E Eu ( II ) / Eu ∗ , E Eu ( III ) / Eu ∗ and formal redox potentials E Eu ( III ) / Eu ( II ) ∗ were determined from open-circuit potentiometry and linear sweep voltammetry data. Some thermodynamic properties relative to the formation of europium di- and trichloride dilute solutions in alkali chloride melts were obtained. The relative partial molar enthalpies of mixing EuCl 2 with alkali chloride melts when dilute solutions are formed, have been measured by electrochemical transient techniques. It was shown that the values determined from electrochemical measurements are in fairly good agreement with those data obtained by a calorimetric method.

Effect of Europium(III) Chloride on the Aggregation Behavior of Sodium Dodecyl Sulfate

The effect of EuCl3 on the aggregation processes of sodium dodecyl sulfate was investigated. Electrical conductivity data, combined with Eu(III) luminescence measurements, suggest that the formation of micelles involving EuCl3 and SDS occurs at low SDS concentration; the formation of these mixed aggregates was also monitored by light scattering, which indicates that the addition of EuCl3 to SDS concentration at values below the critical micelle concentration of the pure surfactant results in a much higher light scattering than that found just with SDS micelles. It was also found that the Eu(III)/DS- complexes are formed with a binding ratio which varies between 20 and 4, depending on the initial concentration of Eu(III). As the concentration increases, turbidity occurs initially, but solutions become clear subsequently. In contrast to the behavior of SDS in the presence of aluminum(III), no flocculation was observed. From the analysis of electrical conductivity data and comparison with other systems, it is suggested that growth of aggregates happens, probably with formation of nonspherical systems. At the highest concentrations these may involve just Eu(III) and DS- ions. The effect of temperature on the SDS micellization process was studied. The calculated free energy of SDS micellization is not dependent on the initial EuCl3 but is dependent on the final balance between the presence of counterions in solution (ionic strength) and the temperature.