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[en] This letter describes the nature of rare-earth dopant state in oxides/borates/vanadate hosts. The dopant charge is controlled by host structure, but not by charge-matching. In the preparation of Eu²⁺ activated blue phosphor Eu(NO₃)₃ is the starting material. Even in the oxidation environment of combustion process Eu³⁺ ion gets reduced into Eu²⁺ in the blue phosphor synthesis. Synthesis of Eu³⁺ activated red phosphor is a straight-forward reaction

[en] It is established that the Eu ions form two type of the luminescence centers. These centers have the energy transfer. The mechanism of energy transfer is reabsorption of radiation. (author)

[en] One of the most intriguing properties involving crystals is their ability to emit light when fractured. While this property was discovered over 200 years ago, no one has ever been able to come up with a complete theory that can predict the physical principles associated with triboluminescence. However, this has not stopped scientists from coming up with various uses for these materials. One such application is to use these materials as the active element for smart impact sensors that can warn of catastrophic impacts. If these sensors are to become a reality however, the material must emit a bright light when fractured. One of the brightest triboluminescent materials found thus far is europium dibenzoylmethide triethylammonium (EuD₄TEA). This material was discovered by Hurt in 1966 and is bright enough to be seen in daylight. In 2011, the authors discovered that synthesizing EuD₄TEA using europium nitrate instead of chloride significantly increased the triboluminescence yield and made the synthesis much easier and more consistent. However, to date, there are few investigations into the effects of dopants on the triboluminescence of EuD₄TEA. This paper reports the investigation of the effects of various dopants on: (1) The triboluminescent light yield, (2) Crystal size and structure, (3) Synthesis time, and (4) Prompt decay time. Results show that inclusion of dopants during synthesis increases the triboluminescence emission of EuD₄TEA by 55%, significantly reduces the synthesis time, and controls the decay time. All of these properties can be useful for constructing the first prototype of a customized impact sensor. - Highlights: ► Doped europium dibenzoylmethide triethylammonium (EuD₄TEA) was synthesized. ► Effects of dopants was studied from EuD₄TEA during low velocity (<10 m/s) impacts. ► The triboluminescent light yield, decay time, and synthesis time were measured. ► A specially-built drop tower was developed to measure triboluminescence from impacts.

[en] A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid-solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H₂SO₄ solution and the grafted resin could be regenerated and reused. (author)

[en] In this paper the results of studying the excitation and fluorescence spectra of co-ordinating compounds of carbamide and biuret with europium nitrate, and influence of organic components on intensity of spectra of initial europium nitrate are presented. It was found that the photoluminescence of europium ions in carbamide compounds possesses a considerable brightness. This is indicative of probability of excited europium ion deactivation. Most bright emission is observed in compounds of europium nitrate with four carbamide molecules and two water ones. (authors)

[en] In this study, we report the comparison between Eu³⁺-doped silica nanoparticles synthesized by Stoeber method using Eu(NO₃)₃ or Eu(acac)₃ as precursors. The impact of different europium species on the properties of the final silica nanospheres is investigated in details in terms of size, morphology, reachable doping amount, and luminescence efficiency. Moreover, the results obtained for different thermal treatments are presented and discussed. It is shown that the organic complex modify the silica growing process, leading to bigger and irregular nanoparticles (500-800 nm) with respect to the perfectly spherical ones (400 nm) obtained by the nitrate salt, but their luminescence intensity and lifetime is significantly higher when 800-900 ^oC annealing is performed.

[en] Mg₃Eu₂(NO₃)₁₂x24H₂O crystals are prepared by crystallization from aqueous solutions. X-ray diffraction analysis is used to determine its crystal structure. Crystals are trigonal; sp.gr. R3-bar, a=13.116(1)A, α=49.34(1) deg, V=1193.1(7) A₃, z=1, ρ_calc=2.161(1) and ρ_meas=2.17(2) g/cm³. Structure is of Mg₃Ce₂(NO₃)₁₂x24H₂O type and is composed of [Mg(H₂O)₆]²⁺ and [Eu(NO₃)₆]^3- complex ions and water molecules arranged between them

[en] To minimize the use of organic solvents and achieve a selective adsorption separation of minor actinides (MA(III)) and Ln(III), adsorbents consisting of SiO₂-P particles impregnated with hexaoctylnitrilotriacetamide (HONTA) were prepared. Batch experiments were performed to evaluate the adsorption properties of the HONTA/SiO₂-P adsorbent for MA(III) and simulated fission products in HNO₃ solution. The uniform distribution of Eu(III) on the adsorbent was confirmed via particle-induced X-ray emission analysis, and X-ray photoelectron spectroscopy revealed that EuNO₃ was the adsorbed species. This study provides a simplified process for the separation of MA(III) using a HONTA/SiO₂-P-packed column. (author)

[en] The extraction of europium(III) nitrate from sodium nitrate with a series of tetrahexylmalonamides has been investigated. The tetrahexylmalonamides considered were N,N,N prime N prime-tetrahexylmalonamide (THMA), N,N,N prime N prime-tetrahexyl-2-methylmalonamide (MeTHMA), and N,N,N primeN prime-tetrahexyl-2,2-dimethylmalonamide (DiMeTHMA). This series allowed for a systematic determination of the effects of alkyl substitution of the methylene carbon. Equilibrium modeling of the extraction data indicates that the malonamide/Eu ratio in the extracted complexes is 3 for all three malonamides investigated. This stoichiometry is different than that determined for isolated complexes. This can be rationalized by the formation of complexes with monodentate-bound diamide ligands in the extracts. The extraction constant for Eu decreases by seven-fold in going from THMA to MeTHMA, and a precipitous drop in the extraction constant occurs upon substitution of a second methyl group on the methylene carbon (i.e., for DiMeTHMA)