Europium Oxide Research Articles

Thermal properties of europium nitrate hexahydrate Eu(NO3)3·6H2O

The hexahydrate of europium nitrate hexahydrate Eu(NO3)3·6H2O shows no phase transitions in the range of −40 to 76 °C when it melts in its own water of crystallization. It was shown that the thermal decomposition is a complex step-wise process, which starts with the simultaneous condensation of 6 mol of the initial monomer Eu(NO3)3·6H2O into a cyclic cluster 6[Eu(NO3)3·6H2O]. This hexamer gradually loses water and nitric acid, and a series of intermediate amorphous oxynitrates is formed. The removal of HNO3 azeotrope is essentially a continuous process occurring in the liquid phase. At higher temperatures, oxynitrates undergo further degradation, lose water, nitrogen dioxide, and oxygen, and finally, after having lost lattice water, are transformed into europium oxide. All mass losses are satisfactorily accounted for under the proposed scheme of thermal decomposition.

Effects of Eu2O3 addition on microstructure, grain-boundary cohesion and wear resistance of high-alumina ceramics

The effects of europium oxide addition on microstructure, bulk density, grain-boundary cohesion and wear resistance of high-alumina ceramics (>97 wt% Al2O3) composed of CaO-MgO-SiO2-Al2O3 have been investigated by normal pressure sintering. The content of Eu2O3 varies from 0 to 0.8 wt%. Test results show that doping with a small amount of Eu2O3 decreases the bulk density and wear resistance of high-alumina ceramics. The phase compositions and microstructure of samples were measured by XRD and FESEM, respectively. XRD result shows that Eu can be dissolved into CaAl12O19 crystallites to form a solid solution. SEM result shows that adding Eu2O3 is easier to generate the plate-like grain and decrease grain size compared with undoped-Eu2O3 of alumina ceramics. The wear resistance mechanism was discussed. The break form of cross-section happened from transgranular fracture to intergranular fracture, which causing by weaker grain-boundary cohesion, leads to the reduction of wear resistance.

A hydrometallurgical process for the recovery of terbium from fluorescent lamps: Experimental design, optimization of acid leaching process and process analysis

Terbium and rare earths recovery from fluorescent powders of exhausted lamps by acid leaching with hydrochloric acid was the objective of this study. In order to investigate the factors affecting leaching a series of experiments was performed in according to a full factorial plan with four variables and two levels (42).The factors studied were temperature, concentration of acid, pulp density and leaching time. Experimental conditions of terbium dissolution were optimized by statistical analysis. The results showed that temperature and pulp density were significant with a positive and negative effect, respectively. The empirical mathematical model deducted by experimental data demonstrated that terbium content was completely dissolved under the following conditions: 90 °C, 2 M hydrochloric acid and 5% of pulp density; while when the pulp density was 15% an extraction of 83% could be obtained at 90 °C and 5 M hydrochloric acid. Finally a flow sheet for the recovery of rare earth elements was proposed. The process was tested and simulated by commercial software for the chemical processes. The mass balance of the process was calculated: from 1 ton of initial powder it was possible to obtain around 160 kg of a concentrate of rare earths having a purity of 99%. The main rare earths elements in the final product was yttrium oxide (86.43%) following by cerium oxide (4.11%), lanthanum oxide (3.18%), europium oxide (3.08%) and terbium oxide (2.20%). The estimated total recovery of the rare earths elements was around 70% for yttrium and europium and 80% for the other rare earths.

Selective separation of yttrium and europium using Cyanex 572 for applications in fluorescent lamp waste processing

The quest for a circular economy has directed attention towards processing of end-of-life products and industrial streams to recover the valuable fractions these contain. Fluorescent lamp waste is acknowledged to be an important source of yttrium and europium, two of the rare earth elements presently regarded as having critical supply risk. In this study, a commercial extractant for solvent extraction separations of REEs, Cyanex 572, was successfully applied to separate yttrium and europium from solutions obtained during processing of fluorescent lamp waste streams. Yttrium was selectively separated from europium at pHeq=0, followed by further recovery of europium at pHeq=1. Better extraction efficiencies of REEs were achieved using aliphatic diluents e.g. kerosene in comparison to aromatic diluents or long chain alcohols. Increases in temperature in the range 25–65°C led to decreases in the separation factors between yttrium and europium. Stripping with hydrochloric acid solutions at concentrations higher than 3M led to complete recovery of extracted yttrium and europium. Precipitation of these elements from their respective stripping products with oxalic acid, followed by calcination of the precipitate, led to yttrium and europium oxides of 99.82% and 91.60% purity, respectively. A flowsheet that encompass the main steps for fluorescent lamp waste processing is also presented.

Thermochemical synthesis of luminescent materials in the Y2O3–ZnO system doped with Eu3+ ions

Powders were synthesized in the yttrium oxide + zinc oxide system doped with europium oxide by the method of redox combustion of a mixture of yttrium, zinc, and europium nitrates in the presence of saccharose (fuel). The structure and the physicochemical and luminescent properties of the particles being formed and of a ceramic on their basis were examined.

In Vivo 3-Dimensional Radiopharmaceutical-Excited Fluorescence Tomography.

The enhanced optical signals of various radiopharmaceuticals (including Na131I, 18F-FDG, 68GaCl3, Na99mTcO4) by EO nanoparticles were detected in vitro. The location and 3D distribution of the radiopharmaceuticals of REFT were then reconstructed and compared with those of Cerenkov luminescence tomography through the experiments with the phantom, artificial source-implanted mouse models, and mice bearing hepatocellular carcinomas. The mixture of 68GaCl3 and EO nanoparticles possessed the strongest optical signals compared with the other mixtures. The in vitro phantom and implanted mouse studies showed that REFT revealed more accurate 3D distribution of 68GaCl3 REFT can detect more tumors than small-animal PET in hepatocellular carcinoma-bearing mice and achieved more accurate 3D distribution information than Cerenkov luminescence tomography. REFT with EO nanoparticles significantly improves accuracy of localization of radiopharmaceuticals and can precisely localize the tumor in vivo.

Europium oxide containing catalysts for oxidative dehydrogenation of alkanes

A method is developed to incorporate europium into Mg–Al hydrotalcites, which are precursors for oxide catalysts of oxidative dehydrogenation (ODH) of alkanes; samples of oxide catalysts are prepared, where europium oxide and gallium, magnesium, aluminum, chromium, vanadium, molybdenum, and niobium oxides are contained in various combinations. The catalytic properties of these catalysts in the reactions of ethane, propane, and butane ODH are studied. The incorporation of europium into some of our studied multicomponent catalysts enhances the reaction selectivity and increases yields of desired products.

X-ray diffraction, calorimetric, and spectroscopic studies of lithium borate glass activated with various oxide admixtures based on europium

Lithium borate glass activated with europium oxide, europium borate, and europium molybdate has been obtained by melt quenching. It has been found that by excitation with UV light of λex = 365 nm, the highest luminescence intensity is observed in the samples activated with europium molybdate. The extreme europium molybdate concentration at which a sharp drop in the glass optical quality starts is measured. The thermal regions of stability are determined and the thermophysical characteristics (jumps of the thermal capacity in the glass-transition point and thermal effects of crystallization) for lithium borate glass doped with various oxides based on europium are calculated.

Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes 154Sm and 153Eu

Abstract The crystal structures of monoclinic samarium and cubic europium sesquioxide, Sm2O3 and Eu2O3, were reinvestigated by powder diffraction methods (laboratory X-ray, synchrotron, neutron). Rietveld analysis yields more precise structural parameters than previously known, especially for oxygen atoms. Interatomic distances d(Sm–O) in Sm2O3 range from 226.3(4) to 275.9(2) pm [average 241.6(3) pm] for the monoclinic B type Sm2O3 [space group C2/m, a = 1418.04(3) pm, b = 362.660(7) pm, c = 885.48(2) pm, β = 100.028(1)°], d(Eu–O) in Eu2O3 from 229.9(2) to 238.8(2) pm for the cubic bixbyite (C) type [space group Ia3̅, a = 1086.87(1) pm]. Neutron diffraction at 50 K and 2 K did not show any sign for magnetic ordering in Sm2O3. Isotopically enriched 154Sm2O3 and 153Eu2O3 were used for the neutron diffraction work because of the enormous absorption cross section of the natural isotopic mixtures for thermal neutrons. The isotopic purity was determined by inductively coupled plasma – mass spectrometry to be 98.9% for 154Sm and 99.8% for 153Eu. Advanced analysis of the neutron diffraction data suggest that the bound coherent scattering lengths of 154Sm and 153Eu need to be revised. We tentatively propose b c(154Sm) = 8.97(6) fm and b c(153Eu) = 8.85(3) fm for a neutron wavelength of 186.6 pm to be better values for these isotopes, showing up to 8% deviation from accepted literature values. It is shown that inaccurate scattering lengths may result in severe problems in crystal structure refinements causing erroneous structural details such as occupation parameters, which might be critically linked to physical properties like superconductivity in multinary oxides.

Plasma sputtering of Pb1–x Eu x Te films with varied composition and structure

We investigate the sputtering of single-crystal and polycrystalline films of Pb1–xEuxTe (x = 0.02–0.10) in high-frequency inductively coupled argon plasma. Layers of Pb1–xEuxTe are grown via molecular beam epitaxy on barium-fluoride substrates of the (111) orientation at 340 and 200°C. For single-crystal films, the dependence of the sputtering rate on the europium concentration is found. For polycrystalline layers, a decrease in the sputtering rate is observed. This is caused by the effect of europium oxidation at the surface of the polycrystallites.

Glycols functionalized fluorescent Eu2O3 nanoparticles: Functionalization effect on the structural and optical properties

Herein, we report the facile synthesis and detailed characterization of glycols-functionalized Europium oxide (Eu2O3) nanoparticles prepared by simple solution process. For the functionalization of Eu2O3 nanoparticles, four glycols, namely ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG) and tetraethylene glycol (TeEG) were used. All the synthesized glycols-functionalized Eu2O3 nanoparticles were characterized in detail in terms of their morphological, structural, compositional and optical properties. From the detailed characterizations, it was observed that the variation of glycols allow the modulation of water solubility and size control (DLS data: 110 nm for EG, 80 nm for DEG, 135 nm for TEG and 150 nm for TeEG) of synthesized Eu2O3 nanoparticles. The regular changes in the chain length of glycol have provided a direct evidence to investigate the effect on the optical and luminescent properties of synthesized Eu2O3 nanoparticles. The current approach presents a simple and facile method to prepare fluorescent Eu2O3 nanoparticles at ambient reaction conditions.

Luminescent Eu2O3nanocrystals byAspalathus linearis’ extract: structural and optical properties

This contribution reports on the synthesis and the main physical properties of europium oxide nanocrystals synthesized for the first time by a completely green physical–chemistry process using Aspalathus linearis’ leaves natural extract as an effective chelating agent. The structural and optical properties of such biosynthesized nanocrystals were investigated by electron microscopy, selective electron diffraction, energy dispersive spectroscopy, x-rays diffraction, Raman and x-rays photoelectron spectroscopies, as well as room-temperature photoluminescence. The luminescence properties of such cubic nanocrystals with a 16.5 nm average size were characterized by an intense red emission centered at 614.8 nm (D05−F37) with an average time decay of 7.808 μs.

Raman, photoluminescence and EPR spectroscopic characterization of europium(III) oxide–lead dioxide–tellurite glassy network

Raman, photoluminescence and EPR spectroscopies were used to characterize some xEu2O3·(100−x)[4TeO2·PbO2] glasses with x=0–50mol% obtained by melt quenching technique. Raman spectra of these glasses were interpreted in terms of vibration modes of deformed Te–O–Te linkages due to the intercalation of [PbOn] and [EuOn] entities produced by addition of Eu2O3 to the host lead–tellurite glass. Photoluminescence spectra of xEu2O3·(100−x)[4TeO2·PbO2] glasses reveal the presence of Pb2+, Eu2+ and Eu3+ ions. EPR data confirm the presence of Eu2+ ions in the europium–lead–tellurite glassy network and offer information about the compositional evolution of the Eu2+ ions local environment and Eu3+↔Eu2+ redox process. PL and EPR data show that the decrease of the Eu2+ ions luminescence intensity for the x≥40mol% Eu2O3 region is not due to the clusterization of europium ions but is due the decrease of the amount of Eu2+ ions as result of changes in the Eu3+→Eu2+ redox equilibrium.

Structural and luminescent properties of Gd oxide doped with Eu3+ embedded in mesopores of SiO2 particles

In this work, we investigated monodisperse spherical particles of mesoporous silica filled with gadolinium and europium oxide based material (admittedly – gadolinium oxide doped with europium) – mSiO2/a-Gd2O3:Eu3+. The composition of the samples was studied by the electron microprobe analysis. The size distribution and shape of the particles were characterized by scanning electron microscopy. Structural properties of the material were studied by transmission electron microscopy and x-ray diffraction analysis. The local cathodoluminescence (CL) technique was used to study luminescent properties of the material and to thoroughly investigate its structural features. It was demonstrated that CL study of the material enables to identify local environment of luminescent centers that is hard to investigate with conventional structural analysis techniques. The comprehensive study made it possible to conclude that with the suggested synthesis technique the gadolinium and europium based material inside SiO2 mesopores reacts with Si forming an amorphous oxyapatite-like structure that crystalizes into hexagonal Gd4.67(SiO4)3O with P63/m space group.

(Invited) Luminescent Rare-Earth Doped Thin Film Nanostructures As Building Blocks for Nanophotonic and Lighting Applications

Active light emitting nanostructured materials are essential elements for the development of compact and efficient devices in applications such as photonics, lighting, safety, sensing and biotechnology. These nanostructured materials require a suitable design and specific choice of wavelength depending on the targeted application. Rare-earth(RE) ions are known for providing a robust and high purity light emission Within this context we aim to design and fabricate nanostructured efficient emitters that will be used as building blocks for the development of the next generation of complex photonic devices that will have integrated functionalities such as emission, switching, processing and detection of light, operating in a wide wavelength range covering the visible-infrared spectrum. In this talk we will present the recent results obtained by our group using the methodology of embedding nanolayers of rare-earth ions into thin film oxides and oxinitrides with the aim to build efficient nanoemitters. By suitably choosing the nature, composition and crystallinity of the matrix, and the oxidation state of the RE-ion and its concentration and distribution in the nanolayers we will show several examples of functionalized emission. The examples will include the demonstration of narrow emission from pure europium oxide thin films in which fine tuning of the emission is shown by exploiting crystal field effects triggered by stress, the development of efficient wide band emitters in the visible based on Eu2+ doped oxide and oxinitride films, and the demonstration of RGB emission based on a combined doping of RE-ions.

Interface Engineering to Create a Strong Spin Filter Contact to Silicon.

Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: (i) an in situ hydrogen-Si (001) passivation and (ii) the application of oxygen-protective Eu monolayers–without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime–and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si (001) in order to create a strong spin filter contact to silicon.

Enhancement of the photocatalytic activity of europium(III) oxide by the deposition of gold for the removal of atrazine

Europium(III) oxide nanoparticles were prepared using a hydrothermal method. Gold was deposited by a photo-assisted deposition method. Europium(III) oxide and gold deposited europium(III) oxide were characterized using different techniques. The results demonstrated that gold was present as a metallic gold, and it was well-dispersed on the europium(III) oxide surface. The photocatalytic activity of europium(III) oxide and gold deposited europium(III) oxide was measured by the degradation of atrazine using visible light irradiation. The photocatalytic activity of gold deposited europium(III) oxide is higher than that of europium(III) oxide. This finding can be attributed to the synergic effect between europium(III) oxide and gold. Moreover, the results revealed that an increase in the weight percent of gold increases the photocatalytic activity of europium(III) oxide, and the most active photocatalyst is 0.20 wt % gold deposited europium(III) oxide. The photocatalyst of 0.20 wt % gold deposited europium(III) oxide has high photocatalytic stability and can be reused five times without a decrease in photocatalytic activity.

Hydrothermally driven three-dimensional evolution of mesoporous hierarchical europium oxide hydrangea microspheres for non-enzymatic sensors of hydrogen peroxide detection

Hydrothermal synthesis of mesoporous europium oxide hierarchical hydrangea microspheres for electrochemical detection of hydrogen peroxide (H2O2) has been successfully achieved.

FTIR and Optical Properties of Europium Doped Lithium Zinc Bismuth Borate Glasses

Alkali oxide,zinc bismuth borate glasses with composition xLi2O-15ZnO-20Bi2O3-(63-x) - B2O3-2EuO [where x= 0, 5, 10, 15 mole%] doped with Europium oxide (2% in the total composition),were prepared by melt quenching technique. The amorphous nature of the prepared glasses was confirmed by X-ray diffraction studies.The glass transition temperature (Tg) values were evaluated from Differential scanning calorimetry (DSC) thermograms, which confirms the glassy nature. By using Archimedes principle,density of the samples was evaluated. Molar volume was calculated from the density data. The IR vibrational studies and structural changes in the boron and bismuth co-ordination with composition were investigated using FT-IR spectroscopy. The optical absorption spectra were recorded in the wave length 200-900nm, cutoff wavelengths, direct, indirect optical band gaps, Urbach energy, reflection loss, refractive index, Molar refraction (Rm), Molar electronic polarizability (αm) values were evaluated.

Europium Oxide-Hematite Magnetic Ceramic Nanoparticles

ABSTRACTNanoparticle system with the composition xEu2O3-(1-x)α-Fe2O3 (x = 0.1 and 0.5) was successfully synthesized by mechanochemical activation of Eu2O3 and α-Fe2O3 mixtures for 0-12 hours of ball milling time. The study is of relevance to catalysis, biomedical, sensing and energy-related applications. 57Fe and 151Eu Mössbauer spectroscopy were used to investigate the phase evolution, solid solution formation and hyperfine parameters of xEu2O3-(1-x)α-Fe2O3 nanoparticle system under the mechanochemical activation process. The 57Fe Mössbauer studies showed that the spectrum of the ball milled samples evolved from a sextet for hematite to sextets and a doublet upon duration of the milling process with europium oxide. This indicated the formation of the EuFeO3 perovskite for large x values and long milling times. The 151Eu Mössbauer investigations showed that the isomer shift decreased with increasing milling time for all molar concentrations employed.