Facile synthesis of visible light excited La_1-xGd_xF₃:Eu³⁺ micro-meter sphere using polyvinylpyrrolidone as a template

Lanthanide fluorides exhibited unique luminescent properties in terms of their low phonon energy can restrict the luminescence quenching and extend luminescent lifetimes.Here,a room-temperature co-precipitation method was used to synthesize europium(III) activated La1-xGdxF3 solid phosphors.X-ray diffraction(XRD) data confirmed the crystalline phases of synthesized sample belongs to orthorhombic system.All the as-derived materials exhibited red luminescence(5D0→7F1) under the excitation at longer wavelengths(394 and 466 nm).The powder with the most intense emission was achieved in terms of 10 mol.% doping concentration(Eu content,La/Gd=1/9) and sample sintered at 700 oC.Scanning electron microscopy(SEM) investigated the morphology and crystalline of the samples,showing that many regular and large balls(5-10 μmol/L) were dispersed within the micro-meter scale composites.We proved that the above crystal growth structures were controllable and predicable based on the surface functionalization by polyvinylpyrrolidone ligand.     

Photophysical properties of a new ternary europium complex with 2-thenoyltrifluoroacetone and 5-nitro-1,10-phenanthroline

A ligand, 5-nitro-1,10-phenanthroline (phenNO2), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR and 1H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (36.0%) upon ligand excitation and a long 5D0 lifetime (458 μs), which indicated that the ligand phenNO2 could sensitize the luminescence of Eu(III) ion efficiently.     

Evaluation of D113 cation exchange resin for the removal of Eu(III) from aqueous solution

Batch adsorption experiments were conducted for the adsorption of Eu(III) ions from aqueous solution by D113 resin. The results indicated that D113 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 turned from 3.50 to 7.00 and the optimal adsorption condition was in HAc-NaAc medium with pH value of 6.50. The maximum uptake capacity of Eu(III) ions was 290.9 mg/g D113 at 298 K, at an initial pH value of 6.50. The overall adsorption process was best described by Lagergren-first-order kinetics. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The thermodynamic parameters such as free energy (?G) which were all negative, indicated that the adsorption of Eu(III) ions onto D113 resin was spontaneous and the positive value of enthalpy (?H) showed that the adsorption was endothermic in nature. Thomas model was applied to experimental column data to determine the characteristic parameters of column useful for process design. Furthermore, Eu(III) could be eluted by using 3.0 mol/L HCl solution and the D113 resin could be regenerated and reused.     

Photoluminescence of Eu~(2+)-activated Na_(1-x)Al_(1-x)Si_(1+x)O_4 upon UV excitation

A convenient high temperature solid-state reaction method was developed to fabricate Na1-xAl1-xSi1+xO4:Eu2+ phosphors.The as-prepared products were characterized by X-ray diffraction(XRD),photoluminescence(PL),and photoluminescence excitation(PLE).The luminescence of Na1-xAl1-xSi1+xO4:Eu2+ phosphors were characterized by the two corresponding emission centers at 535 and 440 nm.The excitation spectrum extended from 250 to 400 nm.A white light was observed by naked eye upon ultraviolet excitation.The relative...     

锌-铕抗菌材料的制备

通过溶胶-凝胶法制备出Zn-Eu抗菌白炭黑,该产品是一种含有稀土Eu3+的新型无机抗菌材料,与只单载Zn2+的抗菌白炭黑相比,该新型无机抗菌材料的抗菌性能更加显著.通过单因素实验探究Zn2+浓度、Eu3+浓度和反应时间对产品杀菌率的影响,得到最佳制备方案:Zn2+浓度为0.8 mol·L-1、Eu3+浓度0.005 mol·L-1、反应时间1 h.最佳条件下制备得到抗菌性能优良的Zn-Eu抗菌白炭黑,并对其进行FTIR、SEM和ICP-OES表征.FTIR结果显示,Zn2+和Eu3+加入后没有明显改变载体白炭黑的基本结构.SEM和ICP-OES分析表明,Zn-Eu抗菌白炭黑粒径较小,分散性较好并且Zn2+和Eu3+均担载在了载体白炭黑上.     

The Recovery of a Mixed Rare-Earth Oxide and the Preparation of Cerium,Europium and Neodymium Oxides from a South African Phosphoric Acid Sludge by Solvent Extraction

Abstract

A novel process based largely on solvent-extraction methods has been developed for the recovery of rare-earth oxides from waste calcium sulphate sludges obtained during the manufacture of phosphoric acid from a South African apatite ore. A mixed rare-earth oxide (90-98% purity) was first recovered from calcium nitrate leach liquors by extraction with TBP or DBBP, after which it was dissolved in nitric acid to enable pure cerium dioxide (99.98%) to be prepared by selective extraction of cerium(IV) nitrate into TBP. The heavy (yttrium), middle, and light rare-earth fractions were then separated by sequential extraction into D2EHPA at controlled pH values. Pure europium oxide (99.98%) was isolated from the middle fraction by reductive precipitation of europim(II) sulphate, followed by conversion to soluble europium(II) chloride and removal of trivalent rare-earth impurities by extraction with D2EHPA or Versatic 10 acid. Finally, magnet-grade neodymium oxide (95-96%) was obtained from the light rare-earth fraction by extraction of the contained lanthanum, cerium and praseodymium into Aliquat 336 nitrate.     

Structural and photoluminescence studies of Eu3+ doped zinc oxide nanorods prepared by precipitation method

Trivalent europium doped zinc oxide (ZnO:Eu3+) nanocrystals were synthesized via room temperature chemical co-precipitation and they were systematically characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectroscopy. The as-synthesized samples were found to have hexagonal wurtzite coexisted with the intermediate Zn5(OH)8Cl2·H2O phase, while the single hexagonal phase was facilitated due to the calcinations. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods were formed due to low temperature annealing of the as-synthesized samples. The crystallite size of the nanoflakes and nanorods (40-90 nm) were extracted from the XRD pattern which was found to be consistent with scanning electron microscopy (SEM) measurements. The photolumi-nescence (PL) spectra of nanophosphors showed bright red and orange emissions at 618 and 594 nm respectively with efficient broad blue green emission spectrum due to ZnO lattice. Further, a good energy transfer process from ZnO host to Eu3+ was observed in PL emission and excitation spectra of Eu3+ doped ZnO ions. In all, the present nanophosphors were found to have great potentiality for bio-applications.     

Na2BaMg（PO4）2： synthesis, crystal structure and europium photoluminescence properties

Na2BaMg(PO4)2 was synthesized and characterized by X-ray diffraction, differential thermal analysis (DTA), 31P NMR spectroscopy and photoluminescence measurements. This compound crystallized in the P3m...     

Luminescence properties of polymers containing europium complexes with 4-tert-butylbenzoic acid

The binary europium complex EuL3 (L=4-tert-butylbenzoate) and ternary europium complexes EuL3TTA0.1 (TTA=2-thenoyltrifluoroacetone), EuL3DBM0.5 (DBM=dibenzoylmethane) and EuL3phen0.5 (phen=1, 10-phenan...     

Hydrothermal synthesis and luminescent properties of GdVO4 : Eu3+ nanophosphors

Eu³⁺-doped GdVO₄ has been synthesised via hydrothermal method by altering the hydrothermal temperature, reaction time and surfactant. The microstructure and morphology information of the phosphors were investigated via the techniques of X-ray powder diffraction and scanning electronic microscopy, which show that the phosphors wear tetragonal phase and the products present various regular morphologies under different reaction conditions such as bulk and nanoparticle. Moreover, the morphologies of the products have been controlled by altering reaction temperature. In addition, the surfactant was also included to control the morphologies of the products and the phosphors present different morphologies. All the phosphors exhibit the characteristic fluorescence of Eu ion (⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₂). The electric dipole transition ⁵D₀ → ⁷F₂ of Eu³⁺ is dominant indicating that most sites of Eu³⁺ ions in GdVO₄ have no inversion centre. Furthermore, we found that the reaction time and the morphologies have great influence on optical properties.