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Sample records for emitting rare-earth oxides

  1. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  2. Electrochemical Extraction of Rare Earth Metals in Molten Fluorides : Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives

    NARCIS (Netherlands)

    Abbasalizadeh, A.; Malfliet, Annelies; Seetharaman, Seshadri; Sietsma, J.; Yang, Y.

    2017-01-01

    In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation

  3. Rare earth doped zinc oxide varistors

    Science.gov (United States)

    McMillan, April D.; Modine, Frank A.; Lauf, Robert J.; Alim, Mohammad A.; Mahan, Gerald D.; Bartkowiak, Miroslaw

    1998-01-01

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2-4.0% oxide of at least one rare earth element, 0.5-4.0% Co.sub.3 O.sub.4, 0.05-0.4% K.sub.2 O, 0.05-0.2% Cr.sub.2 O.sub.3, 0-0.2% CaO, 0.00005-0.01% Al.sub.2 O.sub.3, 0-2% MnO, 0-0.05% MgO, 0-0.5% TiO.sub.3, 0-0.2% SnO.sub.2, 0-0.02% B.sub.2 O.sub.3, balance ZnO.

  4. Radioluminescence of rare-earth doped aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, M.; Molina, P. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Barros, V. S.; Khoury, H. J.; Elihimas, D. R., E-mail: msantiag@exa.unicen.edu.ar [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, Recife, PE 50740-540 (Brazil)

    2011-10-15

    Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al{sub 2}O{sub 3} samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)

  5. Numerical Simulation on the Device of Rare Earth Oxide Preparation by Rare Earth Chloride Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2015-01-01

    Full Text Available Based on the industrial applications of jet pyrolysis technology and it being used for the production of rare earth oxides, the paper hopes to find out an efficient, economic, and environmental friendly new technology which is suitable for production of rare earth oxides. In this paper, a chloride pyrolysis water model is designed, and standard κ-ε turbulence model and VOF model were coupled to simulate the three-dimensional steady gas-liquid flow in jet reactor. The valuable parameter we got provides strong basis for the experimental equipment manufacturing in thermal state and determining test program. Conclusions show that when the drainage tube diameter is 3 mm, it can guarantee that two-phase distribution of the gas-liquid is more uniform and easy for gas-liquid mixing in the tail region of the Venturi tube. If the fluid near the middle of the duct in front of the Venturi starts to reach equilibrium as constant speed flowing, it proves that elongated pipe is conducive to obtain a stable flow of air required by experiments. In the adjustable pipeline location of the Venturi tube, fluid can form a closed loop and generate reflux in the export where atomization and gas-liquid mixing have good effects.

  6. Robust Visible and Infrared Light Emitting Devices Using Rare-Earth-Doped GaN

    National Research Council Canada - National Science Library

    Steckl, Andrew

    2006-01-01

    Rare earth (RE) dopants (such as Er, Eu, Tm) in the wide bandgap semiconductor (WBGS) GaN are investigated for the fabrication of robust visible and infrared light emitting devices at a variety of wavelengths...

  7. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Science.gov (United States)

    Kaminaga, Kenichi; Sei, Ryosuke; Hayashi, Kouichi; Happo, Naohisa; Tajiri, Hiroo; Oka, Daichi; Fukumura, Tomoteru; Hasegawa, Tetsuya

    Rare earth sesquioxides like Y2O3 are known as widegap insulators with the highly stable closed shell trivalent rare earth ions. On the other hand, rare earth monoxides such as YO have been recognized as gaseous phase, and only EuO and YbO were thermodynamically stable solid-phase rock salt monoxides. In this study, solid-phase rock salt yttrium monoxide, YO, was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO possesses unusual valence of Y2+ ([Kr] 4d1) . In contrast with Y2O3, YO was narrow gap semiconductor with dark-brown color. The electrical conductivity was tunable from 10-1 to 103 Ω-1 cm-1 by introducing oxygen vacancies as electron donor. Weak antilocalization behavior was observed indicating significant spin-orbit coupling owing to 4 d electron carrier. The absorption spectral shape implies the Mott-Hubbard insulator character of YO. Rare earth monoixdes will be new platform of functional oxides. This work was supported by JST-CREST, the Japan Society for the Promotion of Science (JSPS) with Grant-in-Aid for Scientific Research on Innovative Areas (Nos. 26105002 and 26105006), and Nanotechnology Platform (Project No.12024046) of MEXT, Japan.

  8. International strategic minerals inventory summary report; rare-earth oxides

    Science.gov (United States)

    Jackson, W.D.; Christiansen, Grey

    1993-01-01

    Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the

  9. Hydrothermal synthesis of nanostructured rare earth oxide – based phosphors

    OpenAIRE

    Mančić, Lidija; Lojpur, Vesna; Marinković, Bojan; Rabanal, Maria Eugenia; Dramićanin, Miroslav; Milošević, Olivera

    2012-01-01

    Synthesis of nanostructured rare earth oxide-based phosphor particles with enhanced optical characteristics leads to the creation of the new photonic devices with diverse applications. Tailoring of the phosphors quality depends on our ability to utilize the best of their intrinsic structure through the control of nucleation and growth process of the desired phase. A large number of works have contributed to the better control of particle shape and crystal growth in soft-chemistry routes. Here...

  10. New rare-earth quinolinate complexes for organic light-emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, H. [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil); Paolini, T.B. [Chemistry Institute, Department of Fundamental Chemistry, University of São Paulo, USP, 05599-970 São Paulo (Brazil); Niyama, E. [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil); Brito, H.F. [Chemistry Institute, Department of Fundamental Chemistry, University of São Paulo, USP, 05599-970 São Paulo (Brazil); Cremona, M., E-mail: cremona@fis.puc-rio.br [Physics Department, Pontifical Catholic University of Rio de Janeiro, 22453-900 Rio de Janeiro (Brazil)

    2013-01-01

    Because of its thermal and morphological stability and optical and electrical properties, tris(8-hydroxyquinoline) aluminum (Alq{sub 3}) is one of the most widely used electron transporting materials in organic light-emitting devices (OLEDs). The search for substitutes for this compound constitutes an important field of research in organic electronics. We report on a study of a new rare-earth tetrakis 8-hydroxyquinoline complex. Synthesis of tris complexes with rare-earth metals and 8-hydroxyquinoline resulted in unstable compounds. However, the inclusion of an additional quinoline group stabilized these compounds. Li[RE(q){sub 4}] (where RE = La{sup 3+}, Lu{sup 3+} and Y{sup 3+} and q = 8-hydroxyquinoline) were synthesized and then used as the electron-transporting and emitting layer in OLEDs. Thin films were deposited in a high-vacuum environment by thermal evaporation on quartz and silicon substrates. Optical characterization of the RE complexes revealed emission in the 510–525 nm range, the same as that observed for Alq{sub 3}, while absorption was observed at wavelengths of 382 nm for the Y/La complexes and 388 nm for the Lu complex. The OLEDs were fabricated with an indium tin oxide layer (ITO) as the anode, (N,N′-bis (1-naphtyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine) NPB as the hole-transporting layer (25 nm), Li[RE(q){sub 4}] as the electron-transporting and emitting layer (40 nm) and aluminum as the cathode (120 nm). The electroluminescence (EL) spectra showed a broad band from 520 to 540 nm and green-colored emission associated with the 8-hydroxyquinoline ligand. There was an interesting dependence of the maximum energy peak position and half-width of the emission band in the EL spectra on the atomic radius of the RE ion used. The best luminance for the OLEDs produced in this study was achieved with the Li[RE(q){sub 4}] compound. The optical and electrical properties of this OLED were comparable to those of similar devices based on Alq{sub 3

  11. Phase transitions of rare earth oxide films grown on Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Wilkens, Henrik

    2014-01-15

    In this work the structural transitions of the rare earth oxides praseodymia and ceria grown on Si(111) are investigated. It is demonstrated that several of the rare earth intermediate phases can be stabilized by post deposition annealing in ultra high vacuum. However, in most cases no single phased but coexisting species are observed. In addition, the surface structure and morphology of hex-Pr{sub 2}O{sub 3}(0001) as well as reduced ceria films are investigated.

  12. AB-INITIO SIMULATION OF ELECTRONIC FEATURES OF HYPERFINE RARE EARTH OXIDE FILMS FOR SENSORY NANOSYSTEMS

    Directory of Open Access Journals (Sweden)

    A. V. Gulay

    2014-01-01

    Full Text Available Ab-Initio simulation of electronic features of sensoring nanomaterials based on rare earth oxides has been made by the example of yttrium oxide. The simulation method for thin films of nanometer scale consisted in the simulation of the material layer of the thickness equal to unit crystal cell size has been proposed within the VASP simulation package. The atomic bond breakdown in the crystal along one of the coordinate axes is simulated by the increase of a distance between the atomic layers along this axis up to values at which the value of free energy is stabilized. It has been found that the valence and conductivity bands are not revealed explicitly and the band gap is not formed in the hyperfine rare earth oxide film (at the film thickness close to 1 nm. In fact the hyperfine rare earth oxide film loses dielectric properties which were exhibited clear enough in continuum.

  13. Some major aspects of the chemical behavior of rare earth oxides: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S. [Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, E-11510 Puerto Real, Cadiz (Spain)]. E-mail: serafin.bernal@uca.es; Blanco, G. [Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, E-11510 Puerto Real, Cadiz (Spain); Calvino, J.J. [Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, E-11510 Puerto Real, Cadiz (Spain); Omil, J.A. Perez [Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, E-11510 Puerto Real, Cadiz (Spain); Pintado, J.M. [Departamento de Ciencia de los Materiales, Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Universidad de Cadiz, Apartado 40, E-11510 Puerto Real, Cadiz (Spain)

    2006-02-09

    The chemical behavior of sesquioxides and higher rare earth oxides is briefly reviewed. In the first case processes implying no change in the lanthanoid oxidation state are considered, whereas in the second one the analysis is focused on their redox behavior.

  14. Effect of surface deposited rare earth oxide gel characteristics on cyclic oxidation behavior of Fe20-Cr alloys

    Directory of Open Access Journals (Sweden)

    Stela Maria Cristina Fernandes

    2006-06-01

    Full Text Available Rare earths have been used to increase high temperature oxidation resistance of many chromium dioxide and alumina forming alloys. These rare earths can be added as elements (or as oxide dispersions to the alloys or applied as an oxide coating to the alloy surface. The sol-gel technique is considered to be very efficient to apply fine oxide particle coatings. Oxide gel coatings of various rare earths such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, dysprosium, yttrium, erbium and ytterbium have been applied to an iron-chromium alloy to determine their influence on the cyclic oxidation behavior (RT-900 °C of the alloy. The morphology and coverage of the rare earth oxide gels varied with the type of rare earth. The cyclic oxidation resistance of the alloy increased with increase in time at temperature required to reach a specific chromium dioxide layer thickness and this in turn was influenced by the rare earth ion radius and characteristics of the rare earth oxide coating such as morphology, stability, coverage, resistance to thermal stresses and consequently adhesion.

  15. Recycling of the rare earth oxides from spent rechargeable batteries using waste metallurgical slags

    Directory of Open Access Journals (Sweden)

    Tang K.

    2013-01-01

    Full Text Available A high temperature process for recycling spent nickel-metal hydride rechargeable batteries has been recently developed at SINTEF/NTNU. The spent battery modules were first frozen with liquid nitrogen for the de-activation and brittle fracture treatment. The broken steel scraps and plastics were then separated by the mechanical classification and magnetic separation. The remaining positive and negative electrodes, together with the polymer separator, were heated to 600-800oC in order to remove the organic components and further separate the Ni-based negative electrode. XRF analyses indicate that the heat-treated materials consist mainly of nickel, rare earth and cobalt oxides. The valuable rare earth oxides were further recovered by the high-temperature slagging treatment. The waste metallurgical slags, consist mainly of SiO2 and CaO, were used as the rare earth oxide absorbent. After the high temperature slagging treatment, over 98% of nickel and cobalt oxides were reduced to the metal phase; meanwhile almost all rare earth oxides remain in the molten slags. Furthermore, EPMA and XRF analyses of the slag samples indicate that the rare earth oxides selectively precipitate in the forms of solid xSiO2•yCaO•zRe2O3. The matrix of slag phase is Re2O3 deficient, typically being less than 5 wt%. This provides a sound basis to further develop the high-temperature process of concentrating the Re2O3 oxides in slags.

  16. Effects of rare earth doping on multi-core iron oxide nanoparticles properties

    Science.gov (United States)

    Petran, Anca; Radu, Teodora; Borodi, Gheorghe; Nan, Alexandrina; Suciu, Maria; Turcu, Rodica

    2018-01-01

    New multi-core iron oxide magnetic nanoparticles doped with rare earth metals (Gd, Eu) were obtained by a one step synthesis procedure using a solvothermal method for potential biomedical applications. The obtained clusters were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS) and magnetization measurements. They possess high colloidal stability, a saturation magnetization of up to 52 emu/g, and nearly spherical shape. The presence of rare earth ions in the obtained samples was confirmed by EDX and XPS. XRD analysis proved the homogeneous distribution of the trivalent rare earth ions in the inverse-spinel structure of magnetite and the increase of crystal strain upon doping the samples. XPS study reveals the valence state and the cation distribution on the octahedral and tetrahedral sites of the analysed samples. The observed shift of the XPS valence band spectra maximum in the direction of higher binding energies after rare earth doping, as well as theoretical valence band calculations prove the presence of Gd and Eu ions in octahedral sites. The blood protein adsorption ability of the obtained samples surface, the most important factor of the interaction between biomaterials and body fluids, was assessed by interaction with bovine serum albumin (BSA). The rare earth doped clusters surface show higher afinity for binding BSA. In vitro cytotoxicity test results for the studied samples showed no cytotoxicity in low and medium doses, establishing a potential perspective for rare earth doped MNC to facilitate multiple therapies in a single formulation for cancer theranostics.

  17. Magnetic interactions in new fluorite-related rare earth oxides LnLn’{sub 2}RuO{sub 7} (Ln, Ln’=rare earths)

    Energy Technology Data Exchange (ETDEWEB)

    Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp; Doi, Yoshihiro

    2016-07-15

    New fluorite-related quaternary rare earth oxides Pr{sub 2}YRuO{sub 7} and La{sub 2}TbRuO{sub 7} have been prepared. They crystallize in an orthorhombic superstructure of cubic fluorite with space group Cmcm. Through magnetic susceptibility and specific heat measurements, Pr{sub 2}YRuO{sub 7} shows an antiferromagnetic transition at 27 K, which is considerably lowered compared with that for Pr{sub 3}RuO{sub 7}. Analysis of the magnetic specific heat indicates that the magnetic behavior observed at 27 K for Pr{sub 2}YRuO{sub 7} is predominantly due to the magnetic interactions between Ru ions, and that the interactions between the Pr{sup 3+} and Ru{sup 5+} ions are also important. La{sub 2}TbRuO{sub 7} shows magnetic ordering at 9.0 K, which is ascribed to the magnetic ordering between Ru{sup 5+} ions from the analysis of the magnetic specific heat data. - Graphical abstract: New fluorite-related quaternary rare earth oxides Pr{sub 2}YRuO{sub 7} and La{sub 2}TbRuO{sub 7} have been prepared. Through magnetic susceptibility and specific heat measurements, Pr{sub 2}YRuO{sub 7} and La{sub 2}TbRuO{sub 7} show an antiferromagnetic transition at 27 and 9.0 K, respectively. Display Omitted - Highlights: • New fluorite-related quaternary rare earth oxides LnLn’{sub 2}RuO{sub 7} have been prepared. • Pr{sub 2}YRuO{sub 7} shows an antiferromagnetic transition at 27 K. • La{sub 2}TbRuO{sub 7} shows magnetic ordering at 9.0 K. • Their magnetic exchange mechanism has been elucidated by the magnetic entropy change.

  18. Oxidative dehydrogenation of ethane on rare-earth oxide-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Buyevskaya, O.; Baerns, M. [Institut fuer Angewandte Chemie Berlin-Adlershof e.V., Berlin (Germany)

    1998-12-31

    Results on the oxidative dehydrogenation of ethane on rare-earth oxide (REO) based catalysts (Na-P-Sm-O, Sm-Sr(Ca)-O, La-Sr-O and Nd-Sr-O) are described. Oxygen adsorption was found to be a key factor which determines the activity of this type of catalysts. Continuous flow experiments in the presence of catalysts which reveal strong oxygen adsorption showed that the reaction mixture is ignited resulting in an enhanced heat generation at the reactor inlet. The heat produced by the oxidative reactions was sufficient under the conditions chosen for the endothermic thermal pyrolysis which takes place preferentially in the gas phase. Ignition of the reaction mixture is an important catalyst function. Contrary to non-catalytic oxidative dehydrogenation, reaction temperatures above 700 C could be achieved without significant external heat input. Ethylene yields of up to 34-45% (S=66-73%) were obtained on REO-based catalysts under non-isothermal conditions (T{sub max}=810-865 C) at contact times in the order of 30 to 40 ms. (orig.)

  19. Rare earth oxide aero- and xerogels. Tuning porosity and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Bjoern

    2013-11-15

    Heterogeneous catalysts to this day are still largely developed on the basis of trial and error. This is due to the great difficulty of creating custom-designed structures at the nanometer scale using traditional preparation methods. In the course of recent rapid developments in the material sciences, however, it has become possible to create materials with custom-designed properties from the macroscopic down into the nanometer range. The purpose of the present study was to make use of this potential for catalysis. The task was to modify the porosity and composition of selected rare earth oxides that promise well as catalysts with the goal of obtaining good results in terms of oxidative reactions and oxidative coupling. One major focus was on chemical sol-gel methods and in particular on what is referred to as the epoxide addition method. Extensive work was put into the characterisation and catalytic testing of aerogels and xerogels of pure rare earth oxides as well as of hybrid systems of rare earth oxides and aluminium oxide. Furthermore, thin xerogel films and macroporous monoliths were produced, the latter using a direct foaming method. The results of this work confirm the high potential of sol-gel chemistry for making porous materials of variable and controllable porosity and composition available for heterogeneous catalysis and creating more powerful catalysts. [German] Bis heute werden heterogene Katalysatoren ueberwiegend per ''trial and error'' entwickelt. Dies liegt daran, dass es mit Hilfe der traditionellen Herstellungsmethoden sehr schwierig ist, auf der Nanometerskala Strukturen gezielt herzustellen. Im Zuge der rasanten Entwicklungen in den Materialwissenschaften ist es jedoch moeglich geworden, verschiedenste Materialen mit massgeschneiderten Eigenschaften vom makroskopischen bis hinein in den Nanometerbereich herzustellen. Ziel dieser Arbeit war es, dieses Potential fuer die Katalyse zu nutzen. Dabei bestand die Aufgabe darin

  20. Synthesis, characterization and photoluminescent properties of rare-earth hydroxides and oxides nanorods by hydrothermal route

    Science.gov (United States)

    Liu, Shuyang; Liu, Yongjun; Mu, Qiuying; Zhang, Fei; Li, He; Wang, Yude

    2013-06-01

    The stable and crystalline pure phase Ln(OH)3 (Ln=La, Nd, Sm, Eu, Gd, Tb, and Dy) nanorods are synthesized by a facile hydrothermal method using the simple chemical materials (rare-earth chloride hexahydrate LnCl3ṡ6H2O and NH3ṡH2O) and polymer polyvinypyrrolidone (PVP). The as-prepared Ln(OH)3 nanorods can be successfully converted to Ln2O3 nanorods via calcination under appropriate conditions. X-ray diffraction (XRD) spectra, Fourier transformed infrared (FTIR) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-Resolution TEM (HRTEM), and Raman spectroscopy were used to examine the morphologies and microstructures to find out the cause. The analyzed results indicate that the obtained nanorods are rare-earth hydroxides and oxides with 1D nanostructures. The formation mechanism of the Ln(OH)3 and Ln2O3 nanorods was investigated. Optical properties of the Ln(OH)3 and Ln2O3 nanorods were determined by photoluminescence (PL). Ln(OH)3 and Ln2O3 nanorods exhibit a strong blue emission with the strongest narrow bands at about 469 nm corresponding to the intra-4f transitions 5D2→7F6, which have potential applications in fluorescent devices.

  1. Use of rare earth oxides as tracers to identify sediment source areas for agricultural hillslopes

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    C. Deasy

    2010-11-01

    Full Text Available Understanding sediment sources is essential to enable more effective targeting of in-field mitigation approaches to reduce diffuse pollution from agricultural land. In this paper we report on the application of rare earth element oxides to arable soils at hillslope scale in order to determine sediment source areas and their relative importance, using a non-intrusive method of surface spraying. Runoff, sediments and rare earth elements lost from four arable hillslope lengths at a site in the UK with clay soils were monitored from three rainfall events after tracer application. Measured erosion rates were low, reflecting the typical event conditions occurring at the site, and less than 1% of the applied REO tracers were recovered, which is consistent with the results of comparable studies. Tracer recovery at the base of the hillslope was able to indicate the relative importance of different hillslope sediment source areas, which were found to be consistent between events. The principal source of eroded sediments was the upslope area, implying that the wheel tracks were principally conduits for sediment transport, and not highly active sites of erosion. Mitigation treatments for sediment losses from arable hillslopes should therefore focus on methodologies for trapping mobile sediments within wheel track areas through increasing surface roughness or reducing the connectivity of sediment transport processes.

  2. Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

    KAUST Repository

    Li, Yongfeng

    2013-04-29

    As a long-lived theme in solid-state physics, the Kondo effect reflects the many-body physics involving the short-range Coulomb interactions between itinerant electrons and localized spins in metallic materials. Here we show that the Kondo effect is present in ZnO, a prototypical wide-band-gap oxide, doped with a rare-earth element (Gd). The localized 4f electrons of Gd ions do not produce remanent magnetism, but interact strongly with the host electrons, giving rise to a saturating resistance upturn and negative magnetoresistance at low temperatures. Furthermore, the Kondo temperature and resistance can be electrostatically modulated using electric-double-layer gating with liquid ionic electrolyte. Our experiments provide the experimental evidence of tunable Kondo effect in ZnO, underscoring the magnetic interactions between localized and itinerant electrons and the emergent transport behaviors in such doped wide-band-gap oxides.

  3. White OLED using {beta}-diketones rare earth binuclear complex as emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, W.G. [LOEM, Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, PUC-Rio, P.O.Box 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil); Legnani, C. [LOEM, Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, PUC-Rio, P.O.Box 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil); Cremona, M. [LOEM, Departamento de Fisica, Pontificia Universidade Catolica do Rio de Janeiro, PUC-Rio, P.O.Box 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil)]. E-mail: cremona@fis.puc-rio.br; Lima, P.P. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, UFPE-CCEN, Recife, PE, 50670-901 (Brazil); Junior, S.A. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, UFPE-CCEN, Recife, PE, 50670-901 (Brazil); Malta, O.L. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, UFPE-CCEN, Recife, PE, 50670-901 (Brazil)

    2006-01-03

    In this work, the fabrication and the characterization of a white triple-layer OLED using a {beta}-diketones binuclear complex [Eu(btfa){sub 3}phenterpyTb(acac){sub 3}] as the emitting layer is reported. The devices were assembled using a heterojunction between three organic molecular materials: the N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) as hole-transporting layer, the {beta}-diketones binuclear complex and the tris(8-hydroxyquinoline aluminum) (Alq{sub 3}) as the electron transporting layer. All the organic layers were sequentially deposited under high vacuum environment by thermal evaporation onto ITO substrates and without breaking vacuum. Continuous electroluminescence emission was obtained varying the applied bias voltage from 10 to 22 V showing a wide emission band from 400 to 700 nm with about 100 cd/m{sup 2} of luminance. The white emission results from a combined action between the binuclear complex, acting as hole blocking and emitting layer, blue from NPB and the typical Alq{sub 3} green emission. The intensity ratio of the peaks is determined by the layer thickness and by the bias voltage applied to the OLED, allowing us to obtain a color tunable light source.

  4. The Development of HfO2-Rare Earth Based Oxide Materials and Barrier Coatings for Thermal Protection Systems

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan James

    2014-01-01

    Advanced hafnia-rare earth oxides, rare earth aluminates and silicates have been developed for thermal environmental barrier systems for aerospace propulsion engine and thermal protection applications. The high temperature stability, low thermal conductivity, excellent oxidation resistance and mechanical properties of these oxide material systems make them attractive and potentially viable for thermal protection systems. This paper will focus on the development of the high performance and high temperature capable ZrO2HfO2-rare earth based alloy and compound oxide materials, processed as protective coating systems using state-or-the-art processing techniques. The emphasis has been in particular placed on assessing their temperature capability, stability and suitability for advanced space vehicle entry thermal protection systems. Fundamental thermophysical and thermomechanical properties of the material systems have been investigated at high temperatures. Laser high-heat-flux testing has also been developed to validate the material systems, and demonstrating durability under space entry high heat flux conditions.

  5. Thermal conductivity of rare earth-uranium ternary oxides of the type RE 6UO 12

    Science.gov (United States)

    Krishnaiah, M. V.; Seenivasan, G.; Srirama Murti, P.; Mathews, C. K.

    2002-11-01

    The knowledge of thermophysical properties of the rare earth uranium ternary oxides of the type RE 6UO 12 (RE=La, Gd and Dy) is essential to understand the fuel performance during reactor operation and for modeling fuel behavior. Literature on the high temperature properties of this compound is not available and there is no report at all on the thermal conductivity of these compounds. Hence a study of thermal conductivity of this compound has been taken up. The compounds were synthesized by a solution combustion method using metal nitrates and urea. Thermal diffusivity of these compounds was measured by the laser flash method in the temperature range 673-1373 K. The specific heat data was computed using Neumann-Kopp's law. Thermal conductivity was calculated using the measured thermal diffusivity value, density and specific heat data for different temperatures. The temperature dependence of thermal conductivity and the implication of structural aspects of these compounds on the data are discussed here.

  6. Anomalous positive flatband voltage shifts in metal gate stacks containing rare-earth oxide capping layers

    KAUST Repository

    Caraveo-Frescas, J. A.

    2012-03-09

    It is shown that the well-known negative flatband voltage (VFB) shift, induced by rare-earth oxide capping in metal gate stacks, can be completely reversed in the absence of the silicon overlayer. Using TaN metal gates and Gd2O3-doped dielectric, we measure a ∼350 mV negative shift with the Si overlayer present and a ∼110 mV positive shift with the Si overlayer removed. This effect is correlated to a positive change in the average electrostatic potential at the TaN/dielectric interface which originates from an interfacial dipole. The dipole is created by the replacement of interfacial oxygen atoms in the HfO2 lattice with nitrogen atoms from TaN.

  7. Effect of hydrocarbon adsorption on the wettability of rare earth oxide ceramics

    Science.gov (United States)

    Preston, Daniel J.; Miljkovic, Nenad; Sack, Jean; Enright, Ryan; Queeney, John; Wang, Evelyn N.

    2014-07-01

    Vapor condensation is routinely used as an effective means of transferring heat, with dropwise condensation exhibiting a 5 - 7x heat transfer improvement compared to filmwise condensation. However, state-of-the-art techniques to promote dropwise condensation rely on functional hydrophobic coatings, which are often not robust and therefore undesirable for industrial implementation. Natural surface contamination due to hydrocarbon adsorption, particularly on noble metals, has been explored as an alternative approach to realize stable dropwise condensing surfaces. While noble metals are prohibitively expensive, the recent discovery of robust rare earth oxide (REO) hydrophobicity has generated interest for dropwise condensation applications due to material costs approaching 1% of gold; however, the underlying mechanism of REO hydrophobicity remains under debate. In this work, we show through careful experiments and modeling that REO hydrophobicity occurs due to the same hydrocarbon adsorption mechanism seen previously on noble metals. To investigate adsorption dynamics, we studied holmia and ceria REOs, along with control samples of gold and silica, via X-Ray photoelectron spectroscopy (XPS) and dynamic time-resolved contact angle measurements. The contact angle and surface carbon percent started at ≈0 on in-situ argon-plasma-cleaned samples and increased asymptotically over time after exposure to laboratory air, with the rare earth oxides displaying hydrophobic (>90°) advancing contact angle behavior at long times (>4 days). The results indicate that REOs are in fact hydrophilic when clean and become hydrophobic due to hydrocarbon adsorption. Furthermore, this study provides insight into how REOs can be used to promote stable dropwise condensation, which is important for the development of enhanced phase change surfaces.

  8. Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

    Science.gov (United States)

    Hemmer, Eva; Venkatachalam, Nallusamy; Hyodo, Hiroshi; Hattori, Akito; Ebina, Yoshie; Kishimoto, Hidehiro; Soga, Kohei

    2013-11-01

    In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln3+), nanoscopic host materials doped with Ln3+, e.g. Y2O3:Er3+,Yb3+, are promising candidates for NIR-NIR bioimaging. Ln3+-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er3+,Yb3+, have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near

  9. Surface chemistry of rare-earth oxide surfaces at ambient conditions: reactions with water and hydrocarbons

    Science.gov (United States)

    Külah, Elçin; Marot, Laurent; Steiner, Roland; Romanyuk, Andriy; Jung, Thomas A.; Wäckerlin, Aneliia; Meyer, Ernst

    2017-03-01

    Rare-earth (RE) oxide surfaces are of significant importance for catalysis and were recently reported to possess intrinsic hydrophobicity. The surface chemistry of these oxides in the low temperature regime, however, remains to a large extent unexplored. The reactions occurring at RE surfaces at room temperature (RT) in real air environment, in particular, in presence of polycyclic aromatic hydrocarbons (PAHs), were not addressed until now. Discovering these reactions would shed light onto intermediate steps occurring in automotive exhaust catalysts before reaching the final high operational temperature and full conversion of organics. Here we first address physical properties of the RE oxide, nitride and fluoride surfaces modified by exposure to ambient air and then we report a room temperature reaction between PAH and RE oxide surfaces, exemplified by tetracene (C18H12) on a Gd2O3. Our study evidences a novel effect - oxidation of higher hydrocarbons at significantly lower temperatures (~300 K) than previously reported (>500 K). The evolution of the surface chemical composition of RE compounds in ambient air is investigated and correlated with the surface wetting. Our surprising results reveal the complex behavior of RE surfaces and motivate follow-up studies of reactions between PAH and catalytic surfaces at the single molecule level.

  10. Metal oxide nanoparticles embedded in rare-earth matrix for low temperature thermal imaging applications

    Science.gov (United States)

    Rauwel, E.; Galeckas, A.; Rauwel, P.; Hansen, P.-A.; Wragg, D.; Nilsen, O.; Fjellvåg, H.

    2016-05-01

    We report on the synthesis and characterization of nanocomposites comprising of oxide nanoparticles (NPs) (ZnO, CaHfO3 and SrHfO3) embedded in rare-earth oxide (Eu2O3, Nd2O3) matrices by using atomic layer deposition. The different oxide surroundings allowed highlighting the role of interface defects in the recombination processes of charge carriers in the NPs. We provide a comparative analysis of optical absorption and emission properties of the constituents: thin films, free-standing and embedded NPs, and discuss the intrinsic and extrinsic nature of the luminescent sites in different nanocomposites. The photoluminescence properties of ZnO nanocomposites are clearly distinguishable from those of free-standing NPs in terms of overall quantum efficiency as well as intensity ratios of the characteristic blue and green emission bands associated with radiative transitions involving excitons and intrinsic defects, respectively. In contrast to PL enhancement due to surface-passivating effect of the surrounding media in the case of ZnO nanocomposites, the embedment of hafnia perovskites into oxide matrices generally leads to suppressed luminescence in the visible range, thus confirming its extrinsic, surface-defect related nature.

  11. Facile fabrication of graphene-based aerogel with rare earth metal oxide for water purification

    Science.gov (United States)

    Pan, Liupeng; Liu, Shunli; Oderinde, Olayinka; Li, Kewen; Yao, Fang; Fu, Guodong

    2018-01-01

    We report a one-step facile fabrication of macroscopic multifunctional graphene-based aerogel with three-dimensional interconnected networks under the synergistic effects of the reduction of graphene oxide sheets by L-ascorbic acid and in situ simultaneous deposition of nanoparticles on graphene sheets. The functional components, Nd2O3 nanoparticles, can be easily incorporated with graphene sheets to assemble bulk macroscopic graphene materials under mild conditions. The reduced graphene oxide/neodymium oxide (rGO/Nd2O3) aerogel showed remarkable adsorption capacity towards different types of dyes, especially for anionic dyes, with the adsorption capacity for indigo disulphonate (ID) being more than 220 mg g-1 within one hour while the adsorption capacity at equilibrium is as high as 397 mg g-1. The method proposed is proven to be universal to induce macroscopic assembly of reduced graphene sheets with rare earth metal oxides and thus facilitates to accessing various graphene-based multifunctional nanocomposites in the form of macroscopic aerogels.

  12. Microlasers based on high-Q rare-earth-doped aluminum oxide resonators on silicon (Conference Presentation)

    Science.gov (United States)

    Bradley, Jonathan D. B.; Su, Zhan; Frankis, Henry C.; Magden, Emir Salih; Li, Nanxi; Byrd, Matthew; Purnawirman, Purnawirman; Shah Hosseini, Ehsan; Adam, Thomas N.; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R.

    2017-02-01

    One of the key challenges in the field of silicon photonics remains the development of compact integrated light sources. In one approach, rare-earth-doped glass microtoroid and microdisk lasers have been integrated on silicon and exhibit ultra-low thresholds. However, such resonator structures are isolated on the chip surface and require an external fiber to couple light to and from the cavity. Here, we review our recent work on monolithically integrated rare-earth-doped aluminum oxide microcavity lasers on silicon. The microlasers are enabled by a novel high-Q cavity design, which includes a co-integrated silicon nitride bus waveguide and a silicon dioxide trench filled with rare-earth-doped aluminum oxide. In passive (undoped) microresonators we measure internal quality factors as high as 3.8 × 105 at 0.98 µm and 5.7 × 105 at 1.5 µm. In ytterbium, erbium, and thulium-doped microcavities with diameters ranging from 80 to 200 µm we show lasing at 1.0, 1.5 and 1.9 µm, respectively. We observe sub-milliwatt lasing thresholds, approximately 10 times lower than previously demonstrated in monolithic rare-earth-doped lasers on silicon. The entire fabrication process, which includes post-processing deposition of the gain medium, is silicon-compatible and allows for integration with other silicon-based photonic devices. Applications of such rare earth microlasers in communications and sensing and recent design enhancements will be discussed.

  13. β-Zn3BPO7:Mn2+: A novel rare-earth-free possible deep-red emitting phosphor

    Science.gov (United States)

    Han, Bing; Li, Pengju; Zhang, Jie; Jin, Lin; Luo, Wen; Shi, Hengzhen

    2015-04-01

    Novel rare-earth-free deep-red emitting phosphors, β-Zn3(1-x)Mn3xBPO7, were prepared successfully by high temperature solid-state reaction and their photoluminescence properties were investigated. The excitation spectrum consists of a broad excitation band peaking at 255 nm and a group of line-shaped excitation peaks around 350 nm and 500 nm, which can be attributed to the charge transfer transition in Mn2+-O2- bonds and the inner d-d electron transitions of Mn2+ ion, respectively. The emission bands are due to 4T1(4G) → 6A1(6S) transition of the Mn2+ ion and there exists efficient energy transfer from charge transfer state of Mn2+-O2- bonds to Mn2+ ions. The dependence of emission wavelength on Mn2+ concentration is studied. The decay curve of Mn2+ ions luminescence in β-Zn3BPO7:Mn2+ is also measured.

  14. A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li{sub 2}O Salt

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon [Chungbook National University, Chungju (Korea, Republic of); Sohn, Jung Min [Chonbuk National University, Jeonju (Korea, Republic of)

    2016-05-15

    In this study, the electrochemical reduction of RE{sub 2}O{sub 3} (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li{sub 2}O. The electrochemical reduction behavior of the mixed RE{sub 2}O{sub 3}-NiO oxide has been investigated and the reduction path of RE{sub 2}O{sub 3} has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl{sub 3} in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li{sub 2}O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE{sub 2}O{sub 3} on the produced Ni to form intermetallic RENi{sub 5}. The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd{sub 2}O{sub 3} was successfully converted to the metal in the presence of NiO.

  15. Exploring the Role of Adsorption and Surface State on the Hydrophobicity of Rare Earth Oxides.

    Science.gov (United States)

    Lundy, Ross; Byrne, Conor; Bogan, Justin; Nolan, Kevin; Collins, Maurice N; Dalton, Eric; Enright, Ryan

    2017-04-19

    Rare earth oxides (REOs) are attracting attention for use as cost-effective, high-performance dropwise condensers because of their favorable thermal properties and robust nature. However, to engineer a suitable surface for industrial applications, the mechanism governing wetting must be first fully elucidated. Recent studies exploring the water-wetting state of REOs have suggested that these oxides are intrinsically hydrophobic owing to the unique electronic structure of the lanthanide series. These claims have been countered with evidence that they are inherently hydrophilic and that adsorption of contaminants from the environment is responsible for the apparent hydrophobic nature of these surfaces. Here, using X-ray photoelectron spectroscopy and dynamic water contact angle measurements, we provide further evidence to show that REOs are intrinsically hydrophilic, with ceria demonstrating advancing water contact angles of ≈6° in a clean surface state and similar surface energies to two transition metal oxides (≳72 mJ/m(2)). Using two model volatile species, it is shown that an adsorption mechanism is responsible for the apparent hydrophobic property observed in REOs as well as in transition metal oxides and silica. This is correlated with the screening of the polar surface energy contribution of the underlying oxide with apparent surface energies reduced to <40 mJ/m(2) for the case of nonane adsorption. Moreover, we show that the degree of surface hydroxylation plays an important role in the observed contact angle hysteresis with the receding contact angle of ceria increasing from ∼10° to 45° following thermal annealing in an inert atmosphere. Our findings suggest that high atomic number metal oxides capable of strongly adsorbing volatile species may represent a viable paradigm toward realizing robust surface coating for industrial condensers if certain challenges can be overcome.

  16. Understanding and Tuning the Intrinsic Hydrophobicity of Rare-Earth Oxides: A DFT+U Study.

    Science.gov (United States)

    Carchini, Giuliano; García-Melchor, Max; Łodziana, Zbigniew; López, Núria

    2016-01-13

    Rare-earth oxides (REOs) possess a remarkable intrinsic hydrophobicity, making them candidates for a myriad of applications. Although the superhydrophobicity of REOs has been explored experimentally, the atomistic details of the structure at the oxide-water interface are still not well understood. In this work, we report a density functional theory study of the interaction between water and CeO2, Nd2O3, and α-Al2O3 to explain their different wettability. The wetting of the metal oxide surface is controlled by geometric and electronic factors. While the electronic term is related to the acid-base properties of the surface layer, the geometric factor depends on the matching between adsorption sites and oxygen atoms from the hexagonal water network. For all the metal oxides considered here, water dissociation is confined to the first oxide-water layer. Hydroxyl groups on α-Al2O3 are responsible for the strong oxide-water interaction, and thus, both Al- and hydroxyl-terminated wet. On CeO2, the intrinsic hydrophobicity of the clean surface disappears when lattice hydroxyl groups (created by the reaction of water with oxygen vacancies) are present as they dominate the interaction and drive wetting. Therefore, hydroxyls may convert a intrinsic nonwetting surface into a wetting one. Finally, we also report that surface modifications, like cation substitution, do not change the acid-base character of the surface, and thus they show the same nonwetting properties as native CeO2 or Nd2O3.

  17. Rare Earth Oxide Fluoride Nanoparticles And Hydrothermal Method For Forming Nanoparticles

    Science.gov (United States)

    Fulton, John L.; Hoffmann, Markus M.

    2003-12-23

    A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

  18. On the evaluation of stability of rare earth oxides as face coats for investment casting of titanium

    Science.gov (United States)

    Saha, R. L.; Nandy, T. K.; Misra, R. D. K.; Jacob, K. T.

    1990-06-01

    Attempts have been made to evaluate the thermal stability of rare earth oxide face coats against liquid titanium. Determination of microhardness profiles and concentration profiles of oxygen and metallic constituents of oxide in investment cast titanium rods has allowed grActation of relative stability of rare earth oxides. The relative stability of evaluated oxides in the order of increasing stability follows the sequence CeO2 — ZrO2 — Gd2O3 — didymium oxide — Sm2O3 —Nd2O3 — Y2O3. The grading does not follow the free energy data of the formation of these oxides. A better correlation with the experimental observations is obtained when the solubility of the metallic species in titanium is also taken into consideration.

  19. Nanocomposites of graphene oxide and upconversion rare-earth nanocrystals with superior optical limiting performance

    KAUST Repository

    Wei, Wei

    2012-04-20

    Upconversion rare-earth nanomaterials (URENs) possess highly efficient near-infrared (NIR), e.g., 980 nm, laser absorption and unique energy upconversion capabilities. On the other hand, graphene and its derivatives, such as graphene oxide (GO), show excellent performance in optical limiting (OL); however, the wavelengths of currently used lasers for OL studies mainly focus on either 532 or 1064 nm. To design new-generation OL materials working at other optical regions, such as the NIR, a novel nanocomposites, GO-URENs, which combines the advantages of both its components, is synthesized by a one-step chemical reaction. Transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and fluorescence studies prove that the α-phase URENs uniformly attach on the GO surface via covalent chemical bonding, which assures highly efficient energy transfer between URENs and GO, and also accounts for the significantly improved OL performance compared to either GO or URENs. The superior OL effect is also observed in the proof-of-concept thin-film product, suggesting immediate applications in making high-performance laser-protecting products and optoelectronic devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    Science.gov (United States)

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-09

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

  1. OXIDATIVE DEHYDROGENATION OF PROPANE BY RARE EARTH PHOSPHATES SUPPORTED ON AL-PILC

    Directory of Open Access Journals (Sweden)

    Carolina De Los Santos

    2012-12-01

    Full Text Available Catalytic activity in propane oxidative dehydrogenation of rare earth phosphates LnPO4 (where Ln = La, Ce, Pr, Nd, Sm and of the same supported by an aluminum pillared clay, of high specific surface area, is presented. The solids were characterized by TGA, XRD, nitrogen adsorption and immediate analysis after reaction in order to determine eventual carbon formation. Catalytic assays were performed at temperatures in the range 400oC-600oC, the reaction mixture was C3H8/O2/Ar = 10/10/80. All the catalysts were active. The reaction products were H2, CO, CO2, CH4, C2H4 and C3H6 and there were no organic oxygenated compounds detected. Although all the investigated systems were active, the Al-PILC supported catalysts presented a higher activity than the bulk materials. In this context, the samarium supported catalyst showed a propene yield increase from 4% to 10% compared with bulk samarium phosphate at 600°C. This effect was attributed to the increase in the specific surface area.

  2. Synthesis and characterization of rare-earth oxide transition-metal arsenides and selenides

    Energy Technology Data Exchange (ETDEWEB)

    Peschke, Simon Friedrich

    2017-04-06

    The present thesis includes two different quaternary systems that have been studied extensively. On the one hand, several samples of the REFeAsO{sub 1-x}F{sub x} family of iron-based superconductors were prepared using a novel solid state metathesis reaction, which also provided a possibility to prepare late rare-earth compounds of this family at ambient pressure. Comparison of structural and physical properties of those samples with samples from conventional solid state and high pressure syntheses revealed both, commonalities as well as striking differences. The observations gave reason to the conclusion that superconducting properties strongly depend, beside electronic infl uence, on the structural parameters. On the other hand, the quaternary system RE-T-Se-O with T = Ti-Mn was investigated using a NaI/KI flux mediated synthesis route. It has been shown that oC -La{sub 2}O{sub 2}MnSe{sub 2} is exclusively accessible in su fficient purity by the use of a fl ux material. Therefore, further syntheses in this quaternary system were performed by a flux mediated synthesis route leading to a large amount of new materials. Among them, a new polymorph mC-La{sub 2}O{sub 2}MnSe{sub 2} which forms, together with La{sub 4}MnSe{sub 3}O{sub 4} and La{sub 6}MnSe{sub 4}O{sub 6}, the series La{sub 2n+2}MnSe{sub n+2}O{sub 2n+2}. In addition, the alternative preparation method also enabled a large scale synthesis of the first examples of rare-earth chromium oxyselenides with chromium in the oxidation state +II, namely RE{sub 2}CrSe{sub 2}O{sub 2} (RE = La-Nd), which opened the door to study their magnetism in detail by powder neutron diffraction and muon spin rotation techniques. Research into the La-V-Se-O system revealed the first fi ve quaternary compounds of this family with interesting magnetic properties including ferromagnetism, antiferromagnetism, metamagnetism and more complex behaviour. In addition, the crystal structure of two new quaternary titanium containing

  3. Pseudopotential description of rare earths in oxides: The case of Er2Si2O7

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2001-01-01

    The applicability of ultrasoft pseudopotentials to the problem of rare-earth incorporation in silicates is investigated using the compound Er2Si2O7 as a test case. It is found that density-functional theory within the generalized gradient approximation provides a good description of the structural...

  4. Byproduct metals and rare-earth elements used in the production of light-emitting diodes—Overview of principal sources of supply and material requirements for selected markets

    Science.gov (United States)

    Wilburn, David R.

    2012-01-01

    The use of light-emitting diodes (LEDs) is expanding because of environmental issues and the efficiency and cost savings achieved compared with use of traditional incandescent lighting. The longer life and reduced power consumption of some LEDs have led to annual energy savings, reduced maintenance costs, and lower emissions of carbon dioxide, sulfur dioxide, and nitrogen oxides from powerplants because of the resulting decrease in energy consumption required for lighting applications when LEDs are used to replace less-energy-efficient sources. Metals such as arsenic, gallium, indium, and the rare-earth elements (REEs) cerium, europium, gadolinium, lanthanum, terbium, and yttrium are important mineral materials used in LED semiconductor technology. Most of the world's supply of these materials is produced as byproducts from the production of aluminum, copper, lead, and zinc. Most of the rare earths required for LED production in 2011 came from China, and most LED production facilities were located in Asia. The LED manufacturing process is complex and is undergoing much change with the growth of the industry and the changes in demand patterns of associated commodities. In many respects, the continued growth of the LED industry, particularly in the general lighting sector, is tied to its ability to increase LED efficiency and color uniformity while decreasing the costs of producing, purchasing, and operating LEDs. Research is supported by governments of China, the European Union, Japan, the Republic of Korea, and the United States. Because of the volume of ongoing research in this sector, it is likely that the material requirements of future LEDs may be quite different than LEDs currently (2011) in use as industry attempts to cut costs by reducing material requirements of expensive heavy rare-earth phosphors and increasing the sizes of wafers for economies of scale. Improved LED performance will allow customers to reduce the number of LEDs in automotive, electronic

  5. Emission Properties, Solubility, Thermodynamic Analysis and NMR Studies of Rare-Earth Complexes with Two Different Phosphine Oxides

    Directory of Open Access Journals (Sweden)

    Hiroki Iwanaga

    2010-07-01

    Full Text Available The paper proposes novel molecular designs for rare-earth complexes involving the introduction of two different phosphine oxide structures into one rare-earth ion. These designs are effective for improving solubility and emission intensity. Additionally, the complexes are indispensable for realizing high performances in LEDs and security media. The thermodynamic properties of Eu(III complexes are correlated with the solubility. Correlations between coordination structures and emission intensity were explained by NMR analysis. The luminous flux of red LED devices with Eu(III complexes is very high (20 mA, 870 m lumen. A new white LED has its largest spectra intensity in the red region and a human look much more vividly under this light.

  6. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

    Science.gov (United States)

    Schneemeyer, L. F.; Siegrist, T.; Besara, T.; Lundberg, M.; Sun, J.; Singh, D. J.

    2015-07-01

    The family of rare earth molybdenum bronzes, reduced ternary molybdates of composition LnMo16O44, was synthesized and a detailed structural study carried out. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO3-type Mo8O36 structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μB moments on each Mo. We suggest that the Mo8O36 units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal.

  7. Study on silicon oxide coated on silver nanocrystal to enhance fluorescence intensity of rare earth complexes

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Yan-rong; Lin, Xue-mei; Wang, Ai-ling; Wang, Zhong-xia; Kang, Jie; Chu, Hai-bin, E-mail: binghai99@gmail.com; Zhao, Yong-liang, E-mail: hxzhaoyl@163.com

    2014-10-15

    Twelve kinds of rare earth complexes were synthesized using halo-benzoic acid as anion ligand and Sm{sup 3+} and Dy{sup 3+} as central ions, respectively. The complexes were characterized by elemental analysis, rare earth coordination titration and electrospray ionization mass spectra, from which the compositions of the complexes were confirmed to be RE(p-FBA){sub 3}·H{sub 2}O, RE(p-ClBA){sub 3}·2H{sub 2}O, RE(p-BrBA){sub 3}·H{sub 2}O, RE(o-FBA){sub 3}·2H{sub 2}O, RE(o-ClBA){sub 3}·H{sub 2}O, RE(o-BrBA){sub 3}·H{sub 2}O (RE=Sm{sup 3+}, Dy{sup 3+}). Besides, IR spectra and UV–visible absorption spectroscopy indicated that the carboxyl oxygen atoms of ligands coordinated to the rare earth ions. Moreover, Ag@SiO{sub 2} core–shell nanoparticles (NPs) were prepared via a modified Stöber method. The average diameters of silver cores were typically between 60 nm and 70 nm, and the thicknesses of the SiO{sub 2} shells were around 10 nm, 15 nm and 25 nm, respectively. The influence of Ag@SiO{sub 2} NPs on the luminescence properties of the rare earth complexes showed that the luminescence intensities of rare earth complexes were enhanced remarkably. As the thickness of SiO{sub 2} shell increases in the range of 10–25 nm, the effect of metal-enhanced fluorescence become obvious. The mechanism of the changes of the fluorescence intensity is also discussed. - Highlights: • Among 10–25 nm, the thicker the shell thickness, the better the fluorescence effect. • The strong the intensity of the pure complexes, the smaller the multiple enhanced. • The intensity of Sm(p-BrBA){sub 3}·H{sub 2}O is the strongest among Sm(p-XBA){sub 3}·nH{sub 2}O complexes. • The intensity of Dy(p-ClBA){sub 3}·2H{sub 2}O is the strongest among Dy(p-XBA){sub 3}·nH{sub 2}O complexes. • When halogen is in o-position, the intensity of RE(o-ClBA){sub 3}·H{sub 2}O is the strongest.

  8. Novel precursors for the deposition of rare earth oxides; Neuartige Precursor zur Abscheidung von Selten-Erd-Oxiden

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, Mareike

    2010-02-22

    During this work rare earth solvates with nitrate and perchlorate anions have been investigated. All compounds have been structurally characterized and analyzed using thermal gravimetric analysis. The decomposition residues were analyzed using powder diffraction methods. Almost all compounds showed a characteristically intense exothermic decomposition step during the thermal decomposition, most likely caused by an intramolecular redox reaction between the nitrate or perchlorate anion respectively and the organic solvent molecules. The nitrates RE(NO{sub 3}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 2} (RE = Sm, Eu) were isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. The known compound group of dimethoxyethane solvates was then expanded with RE(NO{sub 3}){sub 3}(O{sub 2}C{sub 4}H{sub 10}) (RE = La, Sm, Eu). Considering the possible use as precursor material the already described neodymium compound is also discussed. The thermal decomposition of these compounds yields the respective cubic rare earth oxide and shows the typical intense exothermic decomposition reaction. A variety of different precursor system based on nitrate solvates for the deposition of rare earth oxide layers on a silicon surface was developed and investigated in collaboration with the group of Prof. Dr. Al-Shamery (Univ. Oldenburg). Ultra thin films on a H-Si(111) surface were obtained via the deposition of the precursor, which was dissolved in organic solvents. An oxide layer was detected after the heating of the sample. The film thickness was measured as < 10 nm, whereas the thickness of the film was controlled by the concentration of the precursor solution. Sm(ClO{sub 4}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 3} was isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. Eu(ClO{sub 4}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 2}(MeOH){sub 2} was obtained without

  9. Rare-Earth Free Self-Activated Graphene Quantum Dots and Copper-Cysteamine Phosphors for Enhanced White Light-Emitting-Diodes under Single Excitation

    OpenAIRE

    Dai, Wubin; Lei, Yifeng; Xu, Man; Zhao, Pei; Zhang, Zhanhui; Zhou, Jia

    2017-01-01

    Rare-earth (RE) based phosphors are attractive due to their potential applications. However, owing to the resource issue, these kinds of phosphors are expensive and costly. On the contrary, as for phosphor-convert white light-emitting-diodes (pc-WLEDs), a solution-processed tunable warm white emission LED composite is fabricated in this study under single excitation, with both RE free phosphors graphene quantum dots (GQDs) and Copper-Cysteamine (Cu-Cy). By using microwave-assisted wet-chemica...

  10. Potency of (doped) rare earth oxide particles and their constituent metals to inhibit algal growth and induce direct toxic effects.

    Science.gov (United States)

    Joonas, Elise; Aruoja, Villem; Olli, Kalle; Syvertsen-Wiig, Guttorm; Vija, Heiki; Kahru, Anne

    2017-09-01

    Use of rare earth elements (REEs) has increased rapidly in recent decades due to technological advances. It has been accompanied by recurring rare earth element anomalies in water bodies. In this work we (i) studied the effects of eight novel doped and one non-doped rare earth oxide (REO) particles (aimed to be used in solid oxide fuel cells and gas separation membranes) on algae, (ii) quantified the individual adverse effects of the elements that constitute the (doped) REO particles and (iii) attempted to find a discernible pattern to relate REO particle physicochemical characteristics to algal growth inhibitory properties. Green algae Raphidocelis subcapitata (formerly Pseudokirchneriella subcapitata) were used as a test species in two different formats: a standard OECD201 algal growth inhibition assay and the algal viability assay (a 'spot test') that avoids nutrient removal effects. In the 24h 'spot' test that demonstrated direct toxicity, algae were not viable at REE concentrations above 1mgmetal/L. 72-hour algal growth inhibition EC50 values for four REE salts (Ce, Gd, La, Pr) were between 1.2 and 1.4mg/L, whereas the EC50 for REO particles ranged from 1 to 98mg/L. The growth inhibition of REEs was presumably the result of nutrient sequestration from the algal growth medium. The adverse effects of REO particles were at least in part due to the entrapment of algae within particle agglomerates. Adverse effects due to the dissolution of constituent elements from (doped) REO particles and the size or specific surface area of particles were excluded, except for La2NiO4. However, the structure of the particles and/or the varying effects of oxide composition might have played a role in the observed effects. As the production rates of these REO particles are negligible compared to other forms of REEs, there is presumably no acute risk for aquatic unicellular algae. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

    Energy Technology Data Exchange (ETDEWEB)

    Schneemeyer, L.F. [Department of Chemistry, Montclair State University, Montclair, NJ 07043 (United States); Siegrist, T., E-mail: tsiegrist@fsu.edu [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Besara, T. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Lundberg, M. [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Sun, J. [Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6056 (United States); Singh, D.J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6056 (United States)

    2015-07-15

    The family of rare earth molybdenum bronzes, reduced ternary molybdates of composition LnMo{sub 16}O{sub 44,} was synthesized and a detailed structural study carried out. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO{sub 3}-type Mo{sub 8}O{sub 36} structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μ{sub B} moments on each Mo. We suggest that the Mo{sub 8}O{sub 36} units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal. - Graphical abstract: LnMo{sub 16}O{sub 44} phases comprise corner sharing tetrahedral and octahedral molybdenum ions. The MoO{sub 6} octahedra form Mo{sub 8}O{sub 36} units that are well separated and act like pseudo-atoms, accommodating 11 electrons each. - Highlights: • Single crystal X-ray diffraction refinements of LnMo{sub 16}O{sub 44} single crystals for Ln=Ce, Pr, Nd, Tb, Dy and Ho. • DFT calculations based on LaMo{sub 16}O{sub 44}. • [Mo{sub 8}O{sub 36}] units behaving as superatoms with a net magnetic moment of 1 µ

  12. Review- Magnetic orientation and magnetic anisotropy in paramagnetic layered oxides containing rare-earth ions

    Directory of Open Access Journals (Sweden)

    Shigeru Horii, Atsushi Ishihara, Takayuki Fukushima, Tetsuo Uchikoshi, Hiraku Ogino, Tohru S Suzuki, Yoshio Sakka, Jun-ichi Shimoyama and Kohji Kishio

    2009-01-01

    Full Text Available The magnetic anisotropies and easy axes of magnetization at room temperature were determined, and the effects of rare-earth (RE ions were clarified for RE-based cuprates, RE-doped bismuth-based cuprates and RE-doped Bi-based cobaltite regarding the grain orientation by magnetic field. The easy axis, determined from the powder orientation in a static field of 10 T, depended qualitatively on the type of RE ion for all three systems. On the other hand, the magnetization measurement of the c-axis oriented powders, aligned in static or rotating fields, revealed that the type of RE ion strongly affected not only the directions of the easy axis but also the absolute value of magnetic anisotropy, and an appropriate choice of RE ion is required to minimize the magnetic field used for grain orientation. We also studied the possibility of triaxial grain orientation in high-critical-temperature superconductors by a modulated oval magnetic field. In particular, triaxial orientation was attempted in a high-oxygen-pressure phase of orthorhombic RE-based cuprates Y2Ba4Cu7Oy. Although the experiment was performed in epoxy resin, which is not practical, in-plane alignment within 3° was achieved.

  13. Influence of rare-earth based orthovanadate nanoparticles and cerium oxide on bioenergetic processes in mitochondria of hepatocytes

    Directory of Open Access Journals (Sweden)

    Е. А. Аверченко

    2015-10-01

    Full Text Available The features of influence of newly synthesized nanoparticles (NPs based on the rare earth elements, namely orthovanadates and cerium oxide, with the different geometrical parameters on the mitochondrial potential (ΔΨm and respiration and oxidative phosphorylation of the liver were investigated. Reduction of ΔΨm, as well as the ATP level in isolated mitochondria under influence of orthovanadates and CeO2 (1-2 nm NPs suggests that energy processes in the mitochondria are the target of the action of NPs. The highest inhibitory effect was shown by ekstrasmall spherical (orthovanadate and CeO2 of 1-2 nm particles and only CeO2 with sizes of 8-10 nm have no a negative influence on all investigated parameters.

  14. Environmental life cycle assessment on the separation of rare earth oxides through solvent extraction.

    Science.gov (United States)

    Vahidi, Ehsan; Zhao, Fu

    2017-12-01

    Over the past decade, Rare Earth Elements (REEs) have gained special interests due to their significance in many industrial applications, especially those related to clean energy. While REEs production is known to cause damage to the ecosystem, only a handful of Life Cycle Assessment (LCA) investigations have been conducted in recent years, mainly due to lack of data and information. This is especially true for the solvent extraction separation of REEs from aqueous solution which is a challenging step in the REEs production route. In the current investigation, an LCA is carried out on a typical REE solvent extraction process using P204/kerosene and the energy/material flows and emissions data were collected from two different solvent extraction facilities in Inner Mongolia and Fujian provinces in China. In order to develop life cycle inventories, Ecoinvent 3 and SimaPro 8 software together with energy/mass stoichiometry and balance were utilized. TRACI and ILCD were applied as impact assessment tools and LCA outcomes were employed to examine and determine ecological burdens of the REEs solvent extraction operation. Based on the results, in comparison with the production of generic organic solvent in the Ecoinvent dataset, P204 production has greater burdens on all TRACI impact categories. However, due to the small amount of consumption, the contribution of P204 remains minimal. Additionally, sodium hydroxide and hydrochloric acid are the two impactful chemicals on most environmental categories used in the solvent extraction operation. On average, the solvent extraction step accounts for 30% of the total environmental impacts associated with individual REOs. Finally, opportunities and challenges for an enhanced environmental performance of the REEs solvent extraction operation were investigated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Pyro-Electrochemical Reduction of a Mixture of Rare Earth Oxides and NiO in LiCl molten Salt

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Woo; Jeong, Sang Mun [Department of Chemical Engineering, Chungbuk National University, Cheongju (Korea, Republic of)

    2017-06-15

    An electrochemical reduction of a mixture of NiO and rare earth oxides has been conducted to increase the reduction degree of rare earth oxides. Cyclic voltammetry (CV) measurement was carried out to determine the electrochemical reduction behavior of the mixed oxide in molten LiCl medium. Constant voltage electrolysis was performed with various supplied charges to understand the mechanism of electrochemical reduction of the mixed oxide as a working electrode. After completion of the electrochemical reduction, crystal structure of the reaction intermediates was characterized by using an X-ray diffraction method. The results clearly demonstrate that the rare earth oxide was converted to RE-Ni intermetallics via co-reduction with NiO.

  16. Use of rare earth oxides and iron oxides as soil erosion tracers in water erosion experiments at hillslope scale

    Science.gov (United States)

    Guzmán, G.; Cañasveras, J. C.; Barrón, V.; Boulal, H.; Gómez, H.; Conde, E.; Fernández, M.; Gómez, J. A.

    2010-05-01

    The characteristics of the ideal soil erosion have been defined by several authors, for example by Zhang et al. (2001). Despite intensive research on erosion tracers in the last decades there is not a single tracer fulfilling all these characteristics. That is why research on different soil erosion tracers remains as an active field. Two desirable characteristics in erosion tracers are that they should be relatively inexpensive (to purchase and analyze) and that they should be determined with high accuracy in soil or sediment. The availability of multiple tracers is another of the key requirements. In this communication we present our preliminary results on the use of two different sets of erosion tracers. One set are iron oxides with different magnetic and optical properties (Fe3O4, α-Fe2O3 and FeOOH) analyzed by NIRS and magnetic susceptibility measurements. The other set consists of five rare earth oxides (La2O3, Pr6O11, Nd2O3, Sm2O3 and Gd2O3) analyzed using inductively coupled plasma mass spectrometry (ICP-MS). These two groups were studied under controlled and natural conditions, through several water erosion experiments, in field plots with different soil management, crops and scale. In one experiment these tracers were used to determine the source of sediment within sprinkle irrigated fields planted with cotton on shoulders. For this purpose, rainfall simulations were performed under controlled conditions at two scales, one with a portable rainfall simulator at small scale (0.81m2) and with the sprinkler irrigation system in the whole cotton field (2450 m2). Furrows were tagged with both groups of tracers, keeping shoulders untagged (where cotton was planted). Soil samples before and after the rainfall simulations were collected as well as sediment samples. In another experiment four olive orchard plots (330 m2) with different soil managements (cover crop and conventional tillage) were also tagged with the two groups of tracers. Soil samples were taken at

  17. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    Science.gov (United States)

    Li, Jinhuan; Yang, Xia; Yu, Xiaodan; Xu, Leilei; Kang, Wanli; Yan, Wenhua; Gao, Hongfeng; Liu, Zhonghe; Guo, Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+/TiO 2, where RE = Eu 3+, Pr 3+, Gd 3+, Nd 3+, and Y 3+) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+, Pr 3+)/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+/TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  18. Energy Migration Engineering of Bright Rare-Earth Upconversion Nanoparticles for Excitation by Light-Emitting Diodes.

    Science.gov (United States)

    Zhong, Yeteng; Rostami, Iman; Wang, Zihua; Dai, Hongjie; Hu, Zhiyuan

    2015-11-04

    A novel Nd(3+) -sensitized upconversion nanoparticle (UCNP) that can be excited by near-infrared 740 nm light-emitting diode (LED) lamps with bright upconversion luminescence is designed. Yb(3+) ion distribution is engineered to increase the energy migration efficiency. The benefit of the novel LED-excited UCNPs is demonstrated by imaging of breast cancer cells and enabling an economic handheld semiquantitative visual measurement device. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Design of Higher-k and More Stable Rare Earth Oxides as Gate Dielectrics for Advanced CMOS Devices

    Directory of Open Access Journals (Sweden)

    Yi Zhao

    2012-08-01

    Full Text Available High permittivity (k gate dielectric films are widely studied to substitute SiO2 as gate oxides to suppress the unacceptable gate leakage current when the traditional SiO2 gate oxide becomes ultrathin. For high-k gate oxides, several material properties are dominantly important. The first one, undoubtedly, is permittivity. It has been well studied by many groups in terms of how to obtain a higher permittivity for popular high-k oxides, like HfO2 and La2O3. The second one is crystallization behavior. Although it’s still under the debate whether an amorphous film is definitely better than ploy-crystallized oxide film as a gate oxide upon considering the crystal boundaries induced leakage current, the crystallization behavior should be well understood for a high-k gate oxide because it could also, to some degree, determine the permittivity of the high-k oxide. Finally, some high-k gate oxides, especially rare earth oxides (like La2O3, are not stable in air and very hygroscopic, forming hydroxide. This topic has been well investigated in over the years and significant progresses have been achieved. In this paper, I will intensively review the most recent progresses of the experimental and theoretical studies for preparing higher-k and more stable, in terms of hygroscopic tolerance and crystallization behavior, Hf- and La-based ternary high-k gate oxides.

  20. Rare-earth free yellow-green emitting NaZnPO4:Mn phosphor for lighting applications

    Science.gov (United States)

    Haranath, D.; Mishra, S.; Yadav, S.; Sharma, R. K.; Kandpal, L. M.; Vijayan, N.; Dalai, M. K.; Sehgal, G.; Shanker, V.

    2012-11-01

    Manganese-doped sodium zinc phosphate (NaZnPO4:Mn) phosphor with exceptional features having ultra-violet (UV) to visible absorption (300-470 nm), yellow-green (˜543 nm) broad-band photoluminescence (PL), and appreciable color co-ordinates (x = 0.39, y = 0.58) is reported. It has a crystal structure consisting of discrete PO4 tetrahedra linked by ZnO4 and NaO4 distorted tetrahedral such that three tetrahedra, one of each kind, share one corner. The presence of UV sensitive Zn-O-Zn bonds and their efficient energy transfer to Mn2+ ions resulted in brightest PL and external quantum yield of 63% at 418 nm. Our experiment demonstrated the possibility of producing inexpensive white-light emitting devices for future.

  1. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Yang, Ping, E-mail: pyang@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Zhang, Hailu [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Deng, Zongwu, E-mail: zwdeng2007@sinano.ac.cn [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2013-11-15

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al{sub 2}O{sub 3} were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al{sub 2}O{sub 3} catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al{sub 2}O{sub 3} for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al{sub 2}O{sub 3}. For Pt–Ce/Al{sub 2}O{sub 3} catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy.

  2. Calcium-borosilicate glass-ceramics wasteforms to immobilize rare-earth oxide wastes from pyro-processing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Miae [Department of Materials Science and Engineering and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Heo, Jong, E-mail: jheo@postech.ac.kr [Department of Materials Science and Engineering and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Department of Materials Engineering, Adama Science and Technology University (ASTU), PO Box 1888, Adama (Ethiopia)

    2015-12-15

    Glass-ceramics containing calcium neodymium(cerium) oxide silicate [Ca{sub 2}Nd{sub 8-x}Ce{sub x}(SiO{sub 4}){sub 6}O{sub 2}] crystals were fabricated for the immobilization of radioactive wastes that contain large portions of rare-earth ions. Controlled crystallization of alkali borosilicate glasses by heating at T ≥ 750 °C for 3 h formed hexagonal Ca–silicate crystals. Maximum lanthanide oxide waste loading was >26.8 wt.%. Ce and Nd ions were highly partitioned inside Ca–silicate crystals compared to the glass matrix; the rare-earth wastes are efficiently immobilized inside the crystalline phases. The concentrations of Ce and Nd ions released in a material characterization center-type 1 test were below the detection limit (0.1 ppb) of inductively coupled plasma mass spectroscopy. Normalized release values performed by a product consistency test were 2.64·10{sup −6} g m{sup −2} for Ce ion and 2.19·10{sup −6} g m{sup −2} for Nd ion. Results suggest that glass-ceramics containing calcium neodymium(cerium) silicate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing. - Highlights: • Glass-ceramic wasteforms containing Ca{sub 2}Nd{sub 8-x}Ce{sub x}(SiO{sub 4}){sub 6}O{sub 2} crystals were synthesized to immobilize lanthanide wastes. • Maximum lanthanide oxide waste loading was >26.8 wt.%. • Ce and Nd ions were highly partitioned inside Ca–Nd–silicate crystals compared to glass matrix. • Amounts of Ce and Nd ions released in the material characterization center-type 1 were below the detection limit (0.1 ppb). • Normalized release values performed by a PCT were 2.64• 10{sup −6} g m{sup −2} for Ce ions and 2.19• 10{sup −6} g m{sup −2} for Nd ions.

  3. Nuclear analysis of a rare earth containing protective oxide on aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, J.D.; Paterson, P.J.K. [Royal Melbourne Inst. of Tech., VIC (Australia); Hughes, A.E. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Melbourne, VIC (Australia). Div. of Materials Science

    1996-12-31

    The aim is study was to examine the thickness of the conversion coating as well as the elemental depth distribution of cerium and molybdenum using Rutherford Backscattering Spectroscopy (RBS), Scanning Electron Microscopy (SEM), Scanning Auger Electron Spectroscopy and Forward Recoil Spectroscopy (FRS). In addition, RBS has been used to examine how changes in processing conditions, particularly the treatment temperatures, influences the coating thickness and Ce distribution at each process step. SEM established that a crazed oxide structure was developed over the matrix of the alloy using the above process steps. RBS was chosen to provide elemental concentration versus depth information on these samples since it is largely insensitive to surface topography when the detector is set to high scattering angles. A other advantage of using RBS for this particular system is that the heavy elements incorporated into the coating such as Ce and Mo because of their high atomic number compared to the aluminium oxide, are well separated from aluminium and oxygen at their higher recoil energies. Forward Recoil Spectroscopy is capable of detecting hydrogen and it has been used to confirm that the coating is hydrated and to establish the hydrogen distribution within the final oxide coating on each alloy. 7 refs., 1 tab., 4 figs.

  4. Ethyl Acetate Abatement on Copper Catalysts Supported on Ceria Doped with Rare Earth Oxides.

    Science.gov (United States)

    Carabineiro, Sónia Alexandra Correia; Konsolakis, Michalis; Marnellos, George Emmanouil-Nontas; Asad, Muhammad Faizan; Soares, Olívia Salomé Gonçalves Pinto; Tavares, Pedro Bandeira; Pereira, Manuel Fernando Ribeiro; Órfão, José Joaquim de Melo; Figueiredo, José Luís

    2016-05-17

    Different lanthanide (Ln)-doped cerium oxides (Ce0.5Ln0.5O1.75, where Ln: Gd, La, Pr, Nd, Sm) were loaded with Cu (20 wt. %) and used as catalysts for the oxidation of ethyl acetate (EtOAc), a common volatile organic compound (VOC). For comparison, both Cu-free (Ce-Ln) and supported Cu (Cu/Ce-Ln) samples were characterized by N₂ adsorption at -196 °C, scanning/transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed reduction in H₂. The following activity sequence, in terms of EtOAc conversion, was found for bare supports: CeO₂ ≈ Ce0.5Pr0.5O1.75 > Ce0.5Sm0.5O1.75 > Ce0.5Gd0.5O1.75 > Ce0.5Nd0.5O1.75 > Ce0.5La0.5O1.75. Cu addition improved the catalytic performance, without affecting the activity order. The best catalytic performance was obtained for Cu/CeO₂ and Cu/Ce0.5Pr0.5O1.75 samples, both achieving complete EtOAc conversion below ca. 290 °C. A strong correlation was revealed between the catalytic performance and the redox properties of the samples, in terms of reducibility and lattice oxygen availability. Νo particular correlation between the VOC oxidation performance and textural characteristics was found. The obtained results can be explained in terms of a Mars-van Krevelen type redox mechanism involving the participation of weakly bound (easily reduced) lattice oxygen and its consequent replenishment by gas phase oxygen.

  5. The roles of rare-earth dopants in solution-processed ZnO-based transparent conductive oxides

    Science.gov (United States)

    Hu, Wenbing; Peterson, Rebecca L.

    2017-09-01

    Zinc oxide (ZnO) doped with group III A elements such as boron, aluminum, gallium, and indium forms a transparent conductive oxide with low sheet resistance. The group III B rare-earth elements scandium (Sc) and yttrium (Y) also have three valence electrons and thus may similarly act as n-type dopants. Here, we use an ink process to deposit Sc:ZnO and Y:ZnO nanocrystalline films with Sc and Y concentration of a few atomic percent. After annealing in forming gas, the resistivity of all films was reduced by four orders of magnitude. However, the Sc or Y-doped ZnO films are more resistive than undoped ZnO, and their resistivity is more strongly dependent on film thickness; Sc and Y do not act as electron donors. The cause of this anomalous behavior was studied by electrical measurements, x-ray photoelectron spectroscopy, and scanning spreading resistance spectroscopy. The high resistivity of Y:ZnO and Sc:ZnO compared to ZnO is attributed to phase segregation of insulating yttria and scandia at the nanocrystalline grain boundaries. The strong thickness dependence of Sc:ZnO and Y:ZnO film resistivity is due to surface and bulk depletion, which may be enhanced by the slowing of grain growth caused by the insulating grain boundary layer.

  6. Rare-Earth Free Self-Activated Graphene Quantum Dots and Copper-Cysteamine Phosphors for Enhanced White Light-Emitting-Diodes under Single Excitation.

    Science.gov (United States)

    Dai, Wubin; Lei, Yifeng; Xu, Man; Zhao, Pei; Zhang, Zhanhui; Zhou, Jia

    2017-10-09

    Rare-earth (RE) based phosphors are attractive due to their potential applications. However, owing to the resource issue, these kinds of phosphors are expensive and costly. On the contrary, as for phosphor-convert white light-emitting-diodes (pc-WLEDs), a solution-processed tunable warm white emission LED composite is fabricated in this study under single excitation, with both RE free phosphors graphene quantum dots (GQDs) and Copper-Cysteamine (Cu-Cy). By using microwave-assisted wet-chemical method and with graphite as raw material, cold white fluorescence of the GQDs is obtained. Cu-Cy which shows intense photoluminescence in the red region has the structure where both the thio and amine groups connected with copper and forming cysteamine. Warm white light is achieved by mixing the two self-activated RE free phosphors at the weight ratio of 1: 1.7 under the excitation at 365 nm. The designed optimal LED device has the properties of CIE (x, y) = (0.341, 0.327), T = 4436 K, R = 87.9 EQE = 0.31%. The experimental results demonstrate that RE free phosphor(s) excited under a single chip can open up a new avenue to develop much lower device for warm WLEDs.

  7. Rare-earth free self-luminescent Ca2KZn2(VO4)3 phosphors for intense white light-emitting diodes

    Science.gov (United States)

    Bharat, L. Krishna; Jeon, Soo-Kun; Krishna, Kurugundla Gopi; Yu, Jae Su

    2017-02-01

    The commercially available white-light-emitting diodes (WLEDs) are made with a combination of blue LEDs and yellow phosphors. These types of WLEDs lack certain properties which make them meagerly applicable for general illumination and flat panel displays. The solution for such problem is to use near-ultraviolet (NUV) chips as an excitation source because of their high excitation efficiency and good spectral distribution. Therefore, there is an active search for new phosphor materials which can be effectively excited within the NUV wavelength range (350-420 nm). In this work, novel rare-earth free self-luminescent Ca2KZn2(VO4)3 phosphors were synthesized by a citrate assisted sol-gel method at low calcination temperatures. Optical properties, internal quantum efficiency and thermal stability as well as morphology and crystal structure of Ca2KZn2(VO4)3 phosphors for their application to NUV-based WLEDs were studied. The crystal structure and phase formation were confirmed with XRD patterns and Rietveld refinement. The optical properties of these phosphor materials which can change the NUV excitation into visible yellow-green emissions were studied. The synthesized phosphors were then coated onto the surface of a NUV chip along with a blue phosphor (LiCaPO4:Eu2+) to get brighter WLEDs with a color rendering index of 94.8 and a correlated color temperature of 8549 K.

  8. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Li Jinhuan [Key Laboratory of Education Ministry for Enhanced Oil Recovery, Daqing Petroleum Institute, Daqing 163318 (China); Yang Xia; Yu Xiaodan; Xu, Leilei [School of Chemistry, Northeast Normal University, Changchun 130024 (China); Kang Wanli [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China) and Enhanced Oil Recovery Research Center, China University of Petroleum, Qingdao 266555 (China)], E-mail: kangwanli@126.com; Yan Wenhua; Gao Hongfeng; Liu Zhonghe [Key Laboratory of Education Ministry for Enhanced Oil Recovery, Daqing Petroleum Institute, Daqing 163318 (China); Guo Yihang [School of Chemistry, Northeast Normal University, Changchun 130024 (China)], E-mail: guoyh@nenu.edu.cn

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE{sup 3+}/TiO{sub 2}, where RE = Eu{sup 3+}, Pr{sup 3+}, Gd{sup 3+}, Nd{sup 3+}, and Y{sup 3+}) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO{sub 2} were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu{sup 3+} (Gd{sup 3+}, Pr{sup 3+})/TiO{sub 2} composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE{sup 3+}/TiO{sub 2} composite was put forward based on the intermediates produced during the photocatalysis procedure.

  9. Thermochemistry of rare earth doped uranium oxides Ln x U 1-x O 2-0.5x+y (Ln = La, Y, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Navrotsky, Alexandra

    2015-10-01

    Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10–50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

  10. Toxicity of Nine (Doped) Rare Earth Metal Oxides and Respective Individual Metals to Aquatic Microorganisms Vibrio fischeri and Tetrahymena thermophila.

    Science.gov (United States)

    Kurvet, Imbi; Juganson, Katre; Vija, Heiki; Sihtmäe, Mariliis; Blinova, Irina; Syvertsen-Wiig, Guttorm; Kahru, Anne

    2017-07-05

    Despite the increasing use of rare earth elements (REEs) and oxides (REOs) in various technologies, the information on their ecotoxicological hazard is scarce. Here, the effects of La(3+), Ce(3+), Pr(3+), Nd(3+), Gd(3+), CeO₂, and eight doped REOs to marine bacteria Vibrio fischeri and freshwater protozoa Tetrahymena thermophila were studied in parallel with REO dopant metals (Co(2+), Fe(3+), Mn(2+), Ni(2+), Sr(2+)). The highest concentrations of REOs tested were 100 mg/L with protozoa in deionized water and 500 mg/L with bacteria in 2% NaCl. Although (i) most REOs produced reactive oxygen species; (ii) all studied soluble REEs were toxic to bacteria (half-effective concentration, EC50 3.5-21 mg metal/L; minimal bactericidal concentration, MBC 6.3-63 mg/L) and to protozoa (EC50 28-42 mg/L); and (iii) also some dopant metals (Ni(2+), Fe(3+)) proved toxic (EC50 ≤ 3 mg/L), no toxicity of REOs to protozoa (EC50 > 100 mg/L) and bacteria (EC50 > 500 mg/L; MBC > 500 mg/L) was observed except for La₂NiO₄ (MBC 25 mg/L). According to kinetics of V. fischeri bioluminescence, the toxicity of REEs was triggered by disturbing cellular membrane integrity. Fortunately, as REEs and REOs are currently produced in moderate amounts and form in the environment insoluble salts and/or oxides, they apparently present no harm to aquatic bacteria and protozoa.

  11. The effect of rare earth ions on structural, morphological and thermoelectric properties of nanostructured tin oxide based perovskite materials

    Science.gov (United States)

    Rajasekaran, P.; Alagar Nedunchezhian, A. S.; Yalini Devi, N.; Sidharth, D.; Arivanandhan, M.; Jayavel, R.

    2017-11-01

    Metal oxide based materials are promising for thermoelectric applications especially at elevated temperature due to their high thermal stability. Recently, perovskite based oxide materials have been focused as a novel thermoelectric material due to their tunable electrical conductivity. Thermoelectric properties of BaSnO3 has been extensively investigated. However, the effect of various rare earth doping on the thermoelectric properties of BaSnO3 is not studied in detail. In the present work, Ba1‑x RE x SnO3 (RE  =  La and Sr) materials with x  =  0.05 were prepared by polymerization complex (PC) method in order to study the effect of RE incorporation on the structural, morphological and thermoelectric characteristics of BaSnO3. The structural and morphological properties of the synthesized materials were studied by XRD and TEM analysis. XRD analysis confirmed the mixed phases of the synthesized samples. The TEM images of Ba1‑x Sr x SnO3 shows hexagonal and cubic morphology while, Ba1‑x La x SnO3 exhibit rod like morphology. Various functional groups of the perovskite material were identified using FTIR analysis. Formation of the perovskite material was further confirmed by XPS analysis. The Seebeck coefficient of Ba0.95La0.05SnO3 was relatively higher than that of Ba0.95Sr0.05SnO3, especially at high temperature. The rod like morphology of Ba0.95La0.05SnO3 may facilitate fast electron transport which results high thermal power compared to Ba0.95Sr0.05SnO3 despite of its poor crystalline nature. The substitution of La3+ on the Ba2+ site could vary the carrier density which results high Seebeck coefficient of Ba0.95La0.05SnO3 compared to Ba0.95Sr0.05SnO3. From the experimental results, it is obvious that Ba0.95La0.05SnO3 could be a promising thermoelectric material for high temperature application.

  12. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  13. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  14. Combustion synthesis and thermal expansion measurements of the rare earth-uranium ternary oxides RE 6UO 12 (RE=La, Nd and Sm)

    Science.gov (United States)

    Jena, Hrudananda; Asuvathraman, R.; Govindan Kutty, K. V.

    2000-08-01

    Rare earth-uranium ternary oxides were synthesized by a solution combustion route. The starting materials were the corresponding metal nitrates and urea. In these preparations, the metal nitrates act as oxidizer and urea as fuel. Highly exothermic decomposition of the metal nitrate-urea complexes on heating at about 500 K leads to a combustion process yielding RE 6UO 12 fine powders. Thermal expansion measurements of these compounds were carried out in the temperature range of 298-1173 K by high temperature X-ray powder diffractometry. The observed axial thermal expansion behaviour is explained on the basis of the crystal chemistry of the compounds.

  15. The synthesis and characterization of novel 2D rare earth oxides for the study of frustrated magnetism

    Science.gov (United States)

    Sanders, Marisa Brooke

    Geometric frustration is a rich area of study in condensed matter physics. Competing interactions can result in highly degenerate low temperature states and unusual quantum phenomena, yielding models for probing exotic quasi-particle excitations and statistical mechanics. This dissertation details the synthesis and characterization of novel materials that exhibit geometric frustration. Chapter 1 provides an introduction to solid state chemistry, including the methods and tools of materials characterization. In Chapter 2, the fundamentals of magnetic frustration are explored. Discovering new rare earth-derived geometrically frustrated materials has been of great interest to enhance the fundamental understanding of lanthanide exchange interactions in frustrated magnetism. In particular, the triangular kagome lattice, which resembles the Chinese checkerboard or the Star of David, is notorious for its frustrated geometry. Chapters 3 through 7 focus on novel materials that assume this kagome structure. In Chapters 3 and 4, the synthesis and properties of compounds with an ideal 2D rare earth kagome lattice, RE3Sb3Zn2O14 (RE= La, Pr, Nd, Sm, Eu, Gd) and RE3Sb3Mg2O14 (RE=La, Pr, Sm, Eu, Sm, Tb, Ho), are investigated. Both sets of materials evade magnetic ordering down to 1.8 K. Chapter 5 juxtaposes the magnetism and crystal structures of the 2D kagome Nd3Sb3Mg2O14 with that of a corresponding 3D pyrochlore, Nd2ScNbO7. These materials reveal magnetic ordering transitions below 0.6 K. Chapters 6 and 7 demonstrate the ease of manipulation of the kagome structure with chemical substitution. In Chapter 6, dilution experiments are performed on Nd3-xLaxSb3Mg2O14 and the structures and magnetic properties are assessed. Chapter 7 details the synthesis and physical properties of kagome materials containing both a magnetic rare earth and transition metal, RE3Sb3MnCaO14 and RE3Sb3CoCaO14 (RE=La, Pr, Nd, Sm, Eu). Chapter 8 focuses on the magnetism of KBaRE(BO3)2 (RE=Sm, Eu, Gd, Tb, Dy

  16. Determining hillslope-channel connectivity in an agricultural catchment using rare-earth oxide tracers and random forests.

    Science.gov (United States)

    Masselink, Rens; Temme, Arnaud; Giménez, Rafael; Casalí, Javier; Keesstra, Saskia

    2017-04-01

    Soil erosion from agricultural areas is a large problem, because of off-site effects like the rapid filling of reservoirs. To mitigate the problem of sediments from agricultural areas reaching the channel, reservoirs and other surface waters, it is important to understand hillslope-channel connectivity and catchment connectivity. To determine the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel, it is necessary to obtain data on sediment transport from the hillslopes to the channels. Simultaneously, the factors that influence sediment export out of the catchment need to be studied. For measuring hillslope-channel sediment connectivity, Rare-Earth Oxide (REO) tracers were applied to a hillslope in an agricultural catchment in Navarre, Spain, preceding the winter of 2014-2015. The results showed that during the winter there was no sediment transport from the hillslope to the channel. Analysis of precipitation data showed that total precipitation quantities did not differ much from the mean. However, precipitation intensities were low, causing little sediment mobilisation. To test the implication of the REO results at the catchment scale, two conceptual models for sediment connectivity were assessed using a Random Forest (RF) machine learning method. One model proposes that small events provide sediment for large events, while the other proposes that only large events cause sediment detachment and small events subsequently remove these sediments from near and in the channel. The RF method was applied to a daily dataset of sediment yield from the catchment (N=2451 days), and two subsets of the whole dataset: small events (N=2319) and large events (N=132). For sediment yield prediction of small events, variables related to large preceding events were the most important. The model for large events underperformed and, therefore, we could not draw any immediate conclusions whether small events influence the

  17. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  18. Rare-earth elements

    Science.gov (United States)

    Van Gosen, Bradley S.; Verplanck, Philip L.; Seal, Robert R.; Long, Keith R.; Gambogi, Joseph; Schulz, Klaus J.; DeYoung, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The rare-earth elements (REEs) are 15 elements that range in atomic number from 57 (lanthanum) to 71 (lutetium); they are commonly referred to as the “lanthanides.” Yttrium (atomic number 39) is also commonly regarded as an REE because it shares chemical and physical similarities and has affinities with the lanthanides. Although REEs are not rare in terms of average crustal abundance, the concentrated deposits of REEs are limited in number.Because of their unusual physical and chemical properties, the REEs have diverse defense, energy, industrial, and military technology applications. The glass industry is the leading consumer of REE raw materials, which are used for glass polishing and as additives that provide color and special optical properties to the glass. Lanthanum-based catalysts are used in petroleum refining, and cerium-based catalysts are used in automotive catalytic converters. The use of REEs in magnets is a rapidly increasing application. Neodymium-iron-boron magnets, which are the strongest known type of magnets, are used when space and weight are restrictions. Nickel-metal hydride batteries use anodes made of a lanthanum-based alloys.China, which has led the world production of REEs for decades, accounted for more than 90 percent of global production and supply, on average, during the past decade. Citing a need to retain its limited REE resources to meet domestic requirements as well as concerns about the environmental effects of mining, China began placing restrictions on the supply of REEs in 2010 through the imposition of quotas, licenses, and taxes. As a result, the global rare-earth industry has increased its stockpiling of REEs; explored for deposits outside of China; and promoted new efforts to conserve, recycle, and substitute for REEs. New mine production began at Mount Weld in Western Australia, and numerous other exploration and development projects noted in this chapter are ongoing throughout the world.The REE-bearing minerals are

  19. Layered rare-earth hydroxide nanocones with facile host composition modification and anion-exchange feature: topotactic transformation into oxide nanocones for upconversion.

    Science.gov (United States)

    Zhong, Yishun; Chen, Gen; Liu, Xiaohe; Zhang, Dan; Zhang, Ning; Li, Junhui; Liang, Shuquan; Ma, Renzhi; Qiu, Guanzhou

    2017-06-22

    Conical structures with hollow interiors, namely, nanocones (NCs), may exhibit better carrier transport properties than nanorods or nanotubes, which make them promising candidates for potential applications in optical/display devices, electronics and optoelectronics. Generally, conical structures belong to a metastable state between lamellar and tubular forms due to the extreme curvature causing the increase of internal strain energy. Therefore, it is very difficult to prepare NCs in high yield and purity under mild conditions. Here we firstly demonstrate a general strategy for the synthesis of layered rare-earth hydroxide (LRH) NCs intercalating dodecyl sulfate anions (C12H25SO4-, DS-) using hexamethylenetetramine (C6H12N4, HMT) hydrolysis. The rare-earth cations (RE3+) in the host layer can be conveniently modified and/or doped, resulting in a large family of monometallic (Y, Tb, Er), bi- (Y-Tb, Y-Er) and even tri-metallic (Y-Yb-Er) LRH NCs with adjustable ratios. Moreover, the DS--intercalated LRH NCs can be readily modified with various inorganic or organic anions (e.g., NO3-, Cl-, and CH3COO-, etc.) through a conventional anion-exchange procedure, and the original conical morphology can be perfectly maintained. The anion-exchanged product, for example, NO3--intercalated NCs, can be more easily and topotactically transformed into oxide NCs than the original DS--intercalated form, exempt from the formation of rare-earth oxysulfates induced by the combustion of interlayer DS anions. Taking advantage of this protocol, tri-metallic (Y-Yb-Er) LRH NCs were anion-exchanged into the NO3--intercalated form and subsequently calcined into Y2O3:Yb,Er oxide NCs, which showed efficient upconversion photoluminescence properties. The current strategy may become a general method for the designed synthesis of other related hydroxide and oxide NCs for a wide range of potential applications.

  20. Europium-activated phosphors containing oxides of rare-earth and group-IIIB metals and method of making the same

    Science.gov (United States)

    Comanzo, Holly Ann; Setlur, Anant Achyut; Srivastava, Alok Mani; Manivannan, Venkatesan

    2004-07-13

    Europium-activated phosphors comprise oxides of at least a rare-earth metal selected from the group consisting of gadolinium, yttrium, lanthanum, and combinations thereof and at least a Group-IIIB metal selected from the group consisting of aluminum, gallium, indium, and combinations thereof. A method for making such phosphors comprises adding at least a halide of at least one of the selected Group-IIIB metals in a starting mixture. The method further comprises firing the starting mixture in an oxygen-containing atmosphere. The phosphors produced by such a method exhibit improved absorption in the UV wavelength range and improved quantum efficiency.

  1. Fabrication and sealing performance of rare-earth containing glass–ceramic seals for intermediate temperature solid oxide fuel cell applications

    DEFF Research Database (Denmark)

    Abdoli, H.; Alizadeh, P.; Agersted, Karsten

    2014-01-01

    The opportunity of using two rare-earth metal oxides in an aluminosilicate glass for seal applications was investigated in this work. Substitution of La2O3 with Y2O3 in the system changed thermal and physical properties such as transition temperature, flowing behavior, and thermal expansion...... containing strontium in the composition, well bonded interface was obtained in contact with 8YSZ and SS430 ferritic stainless steel. The hermeticity of the glass seals was maintained after 100h isothermal aging at 800°C. Also the OCV showed insignificant fluctuations with stable average values after 24...

  2. Scarcity of rare earth elements.

    Science.gov (United States)

    de Boer, M A; Lammertsma, K

    2013-11-01

    Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Rare earth element geochemistry of feldspars: examples from Fe-oxide Cu-Au systems in the Olympic Cu-Au Province, South Australia

    Science.gov (United States)

    Kontonikas-Charos, Alkis; Ciobanu, Cristiana L.; Cook, Nigel J.; Ehrig, Kathy; Krneta, Sasha; Kamenetsky, Vadim S.

    2017-10-01

    Rare earth element (REE) fractionation trends in feldspars are reported from Olympic Dam (including Wirrda Well and Phillip's Ridge) and Cape Donington (Port Lincoln), for comparison with two other igneous-hydrothermal terranes within the eastern Gawler Craton: Moonta-Wallaroo and Hillside. The case studies were selected as they represent 1590 Ma Hiltaba Suite and/or 1845 - 1810 Ma Donington Suite granites, and, aside from Cape Donington, are associated with Mesoproterozoic iron-oxide copper gold (IOCG)-type mineralization. Both plagioclase and alkali feldspar were analyzed within selected samples with the purpose of constraining and linking changes in REE concentrations and fractionation trends in feldspars to local and whole-rock textures and geochemistry. Two unique, reproducible fractionation trends were obtained for igneous plagioclase and alkali feldspars, distinguished from one another by light rare earth element enrichment, Eu-anomalies and degrees of fractionation (e.g. La/Lu slopes). Results for hydrothermal albite and K-feldspar indicate that REE concentrations and fractionation trends are generally inherited from igneous predecessors, however in some instances, significant amounts of REE appear to have been lost to the fluid. These results may have critical implications for the formation of world-class IOCG systems, in which widespread alkali metasomatism plays a key role by altering the physical and chemical properties of the host rocks during early stages of IOCG formation, as well as trapping trace elements (including REE).

  4. Structural/surface characterization and catalytic evaluation of rare-earth (Y, Sm and La) doped ceria composite oxides for CH3SH catalytic decomposition

    Science.gov (United States)

    He, Dedong; Chen, Dingkai; Hao, Husheng; Yu, Jie; Liu, Jiangping; Lu, Jichang; Liu, Feng; Wan, Gengping; He, Sufang; Luo, Yongming

    2016-12-01

    A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO2 were synthesized and evaluated by conducting CH3SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H2-TPR, XPS, FT-IR, CO2-TPD and CH3SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH3SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce0.75Y0.25O2-δ), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce0.75La0.25O2-δ) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce2S3) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce0.75Sm0.25O2-δ sample was comparable to that of pure CeO2 catalyst.

  5. Evaluation of rare earth oxides doping SnO2.(Co1/4,Mn3/4O-based varistor system

    Directory of Open Access Journals (Sweden)

    Alessandro Dibb

    2006-09-01

    Full Text Available The present paper aims to verify the inuence of rare earth oxide such as lanthanum (La2O3 and neodymium (Nd2O3 doping SnO2 + 0.25%CoO + 0.75%MnO2 + 0.05%Ta2O5 system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM at different regions of the samples. From such analysis it was found that La2O3 and Nd2O3 oxides cause heterogeneous segregation and precipitation at grain boundary concerning cobalt and manganese, decreasing the nonohmic electrical properties, as discussed, likely due to the increasing of grain boundary non-active potential barriers.

  6. Hydrogen Production from Water by Photolysis, Sonolysis and Sonophotolysis with Solid Solutions of Rare Earth, Gallium and Indium Oxides as Heterogeneous Catalysts

    Directory of Open Access Journals (Sweden)

    Marta Penconi

    2015-07-01

    Full Text Available In this work, we present the hydrogen production by photolysis, sonolysis and sonophotolysis of water in the presence of newly synthesized solid solutions of rare earth, gallium and indium oxides playing as catalysts. From the experiments of photolysis, we found that the best photocatalyst is the solid solution Y0.8Ga0.2InO3 doped by sulphur atoms. In experiments of sonolysis, we optimized the rate of hydrogen production by changing the amount of water, adding ethanol and tuning the power of our piezoelectric transducer. Finally, we performed sonolysis and sonophotolysis experiments in the presence of S:Y0.8Ga0.2InO3 finding a promising synergistic effect of UV-visible electromagnetic waves and 38 kHz ultrasound waves in producing H2.

  7. High temperature oxidation resistance of rare earth chromite coated Fe-20Cr and Fe-20Cr-4Al alloys

    Directory of Open Access Journals (Sweden)

    Marina Fuser Pillis

    2007-09-01

    Full Text Available Doped lanthanum chromite has been used in solid oxide fuel cell (SOFC interconnects. The high costs involved in obtaining dense lanthanum chromite have increased efforts to find suitable metallic materials for interconnects. In this context, the oxidation behavior of lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys at SOFC operation temperature was studied. Isothermal oxidation tests were carried out at 1000 °C for 20, 50 and 200 hours. Cyclic oxidation tests were also carried out and each oxidation cycle consisted of 7 hours at 1000/°C followed by cooling to room temperature. The oxidation measurements and the results of SEM/EDS as well as XRD analyses indicated that lanthanum chromite coated Fe-20Cr and Fe-20Cr-4Al alloys were significantly more resistant to oxidation compared with the uncoated alloys.

  8. Effects of Rare Earth Metals on Steel Microstructures

    OpenAIRE

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Kuo, Chia-Liang; Su, Yen-Hao; Chen, Shin-Hau; Lin, Kuan-Ju; Hsieh, Ping-Hung; Hwang, Weng-Sing

    2016-01-01

    Rare earth metals are used in semiconductors, solar cells and catalysts. This review focuses on the background of oxide metallurgy technologies, the chemical and physical properties of rare earth (RE) metals, the background of oxide metallurgy, the functions of RE metals in steelmaking, and the influences of RE metals on steel microstructures. Future prospects for RE metal applications in steelmaking are also presented.

  9. Distribution of rare earths in uranium oxides of the main types of uranium deposits: Causes and genetic meaning

    Science.gov (United States)

    Vinokurov, S. F.; Golubev, V. N.; Trunova, A. N.; Yudintsev, S. V.

    2017-03-01

    Three groups of industrial uranium deposits that differ in the distribution of lanthanides in U oxides have been recognized. A dependence of the REE distribution type on the Yttrium content and Yttrium index YI = (La + Ce)/Y that controls the formation of REE phases capable of selective accumulation of lanthanides has been discovered. This indicates the important role of crystal-chemical fractionation in the distribution of lanthanides. Preferable accumulation of Sm-Gd by U oxides has been found to occur at relatively low contents of Y. In Proterozoic uranium deposits, the yttrium specialization of oxides predominates, while in most Phanerozoic deposits the lanthanum-cerium specialization is typical. These results extend the possibilities of using REEs in ores for purposes of study of the genesis of various uranium deposits.

  10. Rare-Earth Free Self-Activated Graphene Quantum Dots and Copper-Cysteamine Phosphors for Enhanced White Light-Emitting-Diodes under Single Excitation

    National Research Council Canada - National Science Library

    Wubin Dai; Yifeng Lei; Man Xu; Pei Zhao; Zhanhui Zhang; Jia Zhou

    2017-01-01

    .... On the contrary, as for phosphor-convert white light-emitting-diodes (pc-WLEDs), a solution-processed tunable warm white emission LED composite is fabricated in this study under single excitation, with both RE free phosphors graphene quantum dots (GQDs...

  11. Thin-Film Photoluminescent Properties and the Atomistic Model of Mg2TiO4 as a Non-rare Earth Matrix Material for Red-Emitting Phosphor

    Science.gov (United States)

    Huang, Chieh-Szu; Chang, Ming-Chuan; Huang, Cheng-Liang; Lin, Shih-kang

    2016-12-01

    Thin-film electroluminescent devices are promising solid-state lighting devices. Red light-emitting phosphor is the key component to be integrated with the well-established blue light-emitting diode chips for stimulating natural sunlight. However, environmentally hazardous rare-earth (RE) dopants, e.g. Eu2+ and Ce2+, are commonly used for red-emitting phosphors. Mg2TiO4 inverse spinel has been reported as a promising matrix material for "RE-free" red light luminescent material. In this paper, Mg2TiO4 inverse spinel is investigated using both experimental and theoretical approaches. The Mg2TiO4 thin films were deposited on Si (100) substrates using either spin-coating with the sol-gel process, or radio frequency sputtering, and annealed at various temperatures ranging from 600°C to 900°C. The crystallinity, microstructures, and photoluminescent properties of the Mg2TiO4 thin films were characterized. In addition, the atomistic model of the Mg2TiO4 inverse spinel was constructed, and the electronic band structure of Mg2TiO4 was calculated based on density functional theory. Essential physical and optoelectronic properties of the Mg2TiO4 luminance material as well as its optimal thin-film processing conditions were comprehensively reported.

  12. Preparation and characterization of PbTi0{sub 3} ceramics modified by a natural mixture of rare earth oxides of xenotime

    Energy Technology Data Exchange (ETDEWEB)

    Baltazar-Rodrigues, Jair; Rodrigues Junior, Pedro; Cruz, Gerson K. da, E-mail: jbr@uepg.br [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Departamento de Fisica; Lente, Manuel H.; Eiras, Jose A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Fisica

    2014-01-15

    Lead titanate ceramics modified by xenotime (Xm) with nominal composition (Pb, Xm)TiO{sub 3}, Xm 10 or 15 mol %, were prepared by the conventional oxide mixture technique. Xenotime is a natural mineral consisting of a mixture of rare earth oxides. Thermal, structural and electric properties were investigated through differential and gravimetric thermal analysis, X-ray diffraction and dielectric measurements as a function of temperature. The results of both compositions revealed a higher density and free of cracks ceramic body, compared to pure PbTiO{sub 3} prepared by the same procedure. On the other hand, the structural characteristics and Curie temperature are nearly the same as those of pure PbTiO{sub 3}. The hysteresis loop measured at room temperature revealed a hard ferroelectric material with coercive field of 10.7 kV/cm and a remanent polarization of 0.2 μC/cm{sup 2}. These finding reveal a material with properties that highlight potential to be used as electronic devices that operate at high temperature and high frequencies. (author)

  13. Trace amounts of rare earth elements in high purity samarium oxide by sector field inductively coupled plasma mass spectrometry after separation by HPLC

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira, W.R. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil) and Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), 05409-002 Sao Paulo, SP (Brazil)]. E-mail: walter.pedreira@fundacentro.gov.br; Queiroz, C.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Abrao, A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Rocha, S.M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Vasconcellos, M.E. de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), 05508-900 Sao Paulo, SP (Brazil); Boaventura, G.R. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil); Pimentel, M.M. [Instituto de Geociencias, Universidade de Brasilia (UnB), 70910-900 Brasilia, DF (Brazil)

    2006-07-20

    Today there is an increasing need for high purity rare earth compounds in various fields, the optical, the electronics, the ceramic, the nuclear and geochemistry. Samarium oxide has special uses in glass, phosphors, lasers and thermoelectric devices. Calcium chloride crystals treated with samarium have been employed in lasers, which produce light beams intense enough to burn metal. In general, the inductively coupled plasma mass spectrometry (ICP-MS) presents some advantages for trace element analysis, due to high sensitivity and resolution, when compared with other analytical techniques such as ICP optical emission spectrometry (ICP-OES). In this work, sector field inductively coupled plasma mass spectrometry was used. Sixteen elements (Sc, Y and 14 lanthanides) were determined selectively with the ICP-MS system using a concentration gradient method. The detection limits with the ICP-MS system were about 0.2 (La) pg mL{sup -1} to 8 (Gd) pg mL{sup -1}. The %R.S.D. of the methods varying between 0.9 and 1.5% for a set of five (n = 5) replicates was found for the IPEN's material and for the certificate reference sample. Determination of trace REEs in two high pure samarium oxides samples (IPEN and JMC) was performed. IPEN's material is highly pure (>99.99%) and was successfully analyzed without spectral interference (MO{sup +} and MOH{sup +})

  14. Rare Earth Optical Temperature Sensor

    Science.gov (United States)

    Chubb, Donald L. (Inventor); Jenkins, Phillip (Inventor)

    2004-01-01

    A rare earth optical temperature sensor is disclosed for measuring high temperatures. Optical temperature sensors exist that channel emissions from a sensor to a detector using a light pipe. The invention uses a rare earth emitter to transform the sensed thermal energy into a narrow band width optical signal that travels to a detector using a light pipe. An optical bandpass filter at the detector removes any noise signal outside of the band width of the signal from the emitter.

  15. Rare earth oxide reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics for inert coating of metallic parts for petroleum extraction

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Yoggendra Prasad; Rego, Sheila Alves Bezerra da Costa; Ferreira, Ricardo Artur Sanguinetti [Universidade Federal de Pernambuco (UFPE), Recife (Brazil)

    2012-07-01

    Recent findings of largest known pre-salt petroleum reservoir in Brazil have created an intense demand for new materials capable of withstanding direct contact with the crude petroleum as it is a highly corrosive and chemically reactive fluid. Petroleum drilling equipment, storage tanks and transportation systems suffer from constant physical stress caused by chemical attack of crude petroleum on its structure. Ceramics are materials with high chemical stability in hostile environment and therefore can be used as an inert coating material to resolve such problems. To date, ceramics based on alumina are most widely used in practice where there is demand for high mechanical strength and high fracture toughness. However intrinsic fragility of ceramics is still a fatal factor for their use in mechanical structures. To improve these characteristics, usually ceramics are reinforced with one or more ceramic additives. Mechanical properties of alumina based ceramics improve considerably with the addition of TiO{sub 2}, TiN, ZrO{sub 2} etc. ceramic additives. Nucleation and propagation of cracks is a major problem for ceramic coating applications. Initial studies show that addition of small percentages of rare earth oxides can increase the toughness of the alumina based ceramics. In the present work, we have produced rare-earth oxide (CeO{sub 2}) reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics in proportions of 5-20 wt% TiO{sub 2} and 2%wt% CeO{sub 2} through thermomechanical processing and sintering techniques and studied there microstructural characteristics and mechanical properties. To evaluate the potential of these ceramics as inert coatings for crude petroleum extraction, storage and transportation systems, we have studied the physic-chemical and mechanical stability of these ceramics in crude petroleum environment. Our studies presented satisfactory results in terms of physic-chemical and mechanical stability of these materials for the use of 2wt% of CeO{sub 2

  16. Regional framework and geology of iron oxide-apatite-rare earth element and iron oxide-copper-gold deposits of the Mesoproterozoic St. Francois Mountains Terrane, southeast Missouri

    Science.gov (United States)

    Day, Warren C.; Slack, John F.; Ayuso, Robert A.; Seeger, Cheryl M.

    2016-01-01

    This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite province. The province formed during two major pulses of igneous activity: (1) an older early Mesoproterozoic (ca. 1.50–1.44 Ga) episode of volcanism and granite plutonism, and (2) a younger middle Mesoproterozoic (ca. 1.33–1.30 Ga) episode of bimodal gabbro and granite plutonism. The volcanic rocks are predominantly high-silica rhyolite pyroclastic flows, volcanogenic breccias, and associated volcanogenic sediments with lesser amounts of basaltic to andesitic volcanic and associated subvolcanic intrusive rocks. The iron oxide deposits are all hosted in the early Mesoproterozoic volcanic and volcaniclastic sequences. Previous studies have characterized the St. Francois Mountains terrane as a classic, A-type within-plate granitic terrane. However, our new whole-rock geochemical data indicate that the felsic volcanic rocks are effusive derivatives from multicomponent source types, having compositional similarities to A-type within-plate granites as well as to S- and I-type granites generated in an arc setting. In addition, the volcanic-hosted IOA and IOCG deposits occur within bimodal volcanic sequences, some of which have volcanic arc geochemical affinities, suggesting an extensional tectonic setting during volcanism prior to emplacement of the ore-forming systems.The Missouri iron orebodies are magmatic-related hydrothermal deposits that, when considered in aggregate, display a vertical zonation from high-temperature, magmatic ± hydrothermal IOA deposits emplaced at moderate depths (~1–2 km), to magnetite-dominant IOA veins and IOCG deposits emplaced at shallow

  17. TEMPERATURE TRENDS OF THE PERMITTIVITY IN COMPLEX OXIDES OF RARE-EARTH ELEMENTS WITH PEROVSKITE-TYPE STRUCTURE

    Directory of Open Access Journals (Sweden)

    A.G.Belous

    2003-01-01

    Full Text Available Ceramic materials based on complex oxides with both the perovskite structure (Ln2/3Nb2O6 and the structure of tetragonal tungsten bronze (Ba6-xLn8+2x/3Ti18O54 have been investigated over a wide frequency and temperature ranges. The results obtained for certain structures denote the presence of the temperature anomalies of dielectric parameters (ε, tanδ. These anomalies occur over the wide frequency range including submilimeter (SMM wavelength range, and are related neither with the processing peculiarities nor with the presence of the phase transitions. Temperature behavior of the permittivity has been considered in terms of the polarization mechanism based on the elastic-strain lattice oscillations. It has been assumed that the observed anomalies could be ascribed to a superposition of harmonic and anharmonic contribution to lattice oscillations that determines τε sign and magnitude.

  18. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    Science.gov (United States)

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Structural/surface characterization and catalytic evaluation of rare-earth (Y, Sm and La) doped ceria composite oxides for CH{sub 3}SH catalytic decomposition

    Energy Technology Data Exchange (ETDEWEB)

    He, Dedong; Chen, Dingkai; Hao, Husheng; Yu, Jie; Liu, Jiangping; Lu, Jichang; Liu, Feng [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Wan, Gengping [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Research Center for Analysis and Measurement, Hainan University, Haikou, 570228 (China); He, Sufang [Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming, 650093 (China); Luo, Yongming, E-mail: environcatalysis222@yahoo.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China)

    2016-12-30

    Highlights: • Ce{sub 0.75}RE{sub 0.25}O{sub 2-δ} (RE = Y, Sm and La) were synthesized by citrate complexation method. • Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ} exhibited the best stability for the decomposition of CH{sub 3}SH. • Cation radius played a key role in determining structure and surface characteristics. • Catalytic behavior depended on synergistic role of oxygen vacancies and basic sites. • Ce{sub 2}S{sub 3} accumulation on the surface was responsible for the deactivation of catalyst. - Abstract: A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO{sub 2} were synthesized and evaluated by conducting CH{sub 3}SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H{sub 2}-TPR, XPS, FT-IR, CO{sub 2}-TPD and CH{sub 3}SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH{sub 3}SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ}), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce{sub 0.75}La{sub 0.25}O{sub 2-δ}) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce{sub 2}S{sub 3}) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce{sub 0.75}Sm{sub 0.25}O{sub 2-δ} sample was comparable to that of pure Ce

  20. Replacing the Rare Earth Intellectual Capital

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl

    2011-04-01

    The rare earth crisis slowly evolved during a 10 to 15 year period beginning in the mid-1980s, when the Chinese began to export mixed rare earth concentrates. In the early 1990s, they started to move up the supply chain and began to export the individual rare earth oxides and metals. By the late 1990s the Chinese exported higher value products, such as magnets, phosphors, polishing compounds, catalysts; and in the 21st century they supplied finished products including electric motors, computers, batteries, liquid-crystal displays (LCDs), TVs and monitors, mobile phones, iPods and compact fluorescent lamp (CFL) light bulbs. As they moved to higher value products, the Chinese slowly drove the various industrial producers and commercial enterprises in the US, Europe and Japan out of business by manipulating the rare earth commodity prices. Because of this, the technically trained rare earth engineers and scientists who worked in areas from mining to separations, to processing to production, to manufacturing of semifinished and final products, were laid-off and moved to other fields or they retired. However, in the past year the Chinese have changed their philosophy of the 1970s and 1980s of forming a rare earth cartel to control the rare earth markets to one in which they will no longer supply the rest of the world (ROW) with their precious rare earths, but instead will use them internally to meet the growing demand as the Chinese standard of living increases. To this end, they have implemented and occasionally increased export restrictions and added an export tariff on many of the high demand rare earth elements. Now the ROW is quickly trying to start up rare earth mines, e.g. Molycorp Minerals in the US and Lynas Corp. in Australia, to cover this shortfall in the worldwide market, but it will take about five years for the supply to meet the demand, even as other mines in the ROW become productive. Unfortunately, today there is a serious lack of technically trained

  1. Thermochemistry of rare earth doped uranium oxides Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} (Ln = La, Y, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu

    2015-10-15

    Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10–50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO{sub 1.5}, UO{sub 2} and UO{sub 3} in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3} for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U{sup 5+}, U{sup 6+}, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements. - Highlights: • We synthesize, characterize Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} solid solutions (Ln = La, Y, Nd). • Formation enthalpies become more exothermic with increasing rare earth content. • Oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3}. • Direct calorimetric measurements are in good agreement with free energy data.

  2. Rietveld refinement and dielectric relaxation of a new rare earth based double perovskite oxide: BaPrCoNbO6

    Science.gov (United States)

    Bharti, Chandrahas; Das, Mrinmoy K.; Sen, A.; Chanda, Sadhan; Sinha, T. P.

    2014-02-01

    A new rare earth based double perovskite oxide barium praseodymium cobalt niobate, BaPrCoNbO6 (BPCN) is synthesized by solid-state reaction technique. Rietveld analysis of X-ray diffraction (XRD) data shows that the compound crystallizes in a perovskite like tetragonal structure which belongs to the I4/mmm space group with lattice parameters a=b=5.6828(9) Å, c=8.063(2) Å. Structural analysis reveals 1:1 ordered arrangement for the Co2+ and Nb5+ cations over the six-coordinate B-sites of BPCN. The superlattice line (1 0 1) at 2θ=19.10° arising from the alternate ordering of Co2+ and Nb5+ sites is observed in the XRD pattern which confirms the presence of cation ordering in BPCN. Fourier transform infrared spectrum shows two phonon modes of the sample due to the antisymmetric NbO6 stretching vibration. The relaxation dynamics of the conductive process in BPCN is investigated in the temperature range 303 to 503 K and in the frequency range 100 Hz to 1 MHz using impedance spectroscopy. The relaxation mechanism of the sample in the framework of electric modulus formalism is modeled by Davidson-Cole model (DCM). The values of α (distribution of relaxation time) for the DCM varies from 0.1 to 0.3 which suggests the asymmetric distribution of relaxation time for BPCN. The activation energy of the sample, calculated from both conductivity and modulus spectra, are found to be almost the same ~0.4 eV, which indicates that the conduction mechanism for BPCN is polaron hopping. The scaling behaviour of the imaginary part of electric modulus suggests that the relaxation follows the same mechanism at various temperatures.

  3. Doped to Rare Earth Ions

    African Journals Online (AJOL)

    In the present work, we are interested by studying the spectroscopic properties for optical applications, mainly laser amplification, of MF2 crystals, where M is an alkaline earth (Ba, Sr) or Cadmium (Cd) doped with rare earth ions (Tb3+, Er3+, Ho3+. So far, we present the absorption and emission properties and also the ...

  4. Scarcity of rare earth elements

    NARCIS (Netherlands)

    de Boer, M.A.; Lammertsma, K.

    2013-01-01

    Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other

  5. Effects of Rare Earth Metals on Steel Microstructures

    Directory of Open Access Journals (Sweden)

    Fei Pan

    2016-05-01

    Full Text Available Rare earth metals are used in semiconductors, solar cells and catalysts. This review focuses on the background of oxide metallurgy technologies, the chemical and physical properties of rare earth (RE metals, the background of oxide metallurgy, the functions of RE metals in steelmaking, and the influences of RE metals on steel microstructures. Future prospects for RE metal applications in steelmaking are also presented.

  6. Methods for preparation of nanocrystalline rare earth phosphates for lighting applications

    Science.gov (United States)

    Comanzo, Holly Ann; Manoharan, Mohan; Martins Loureiro, Sergio Paulo; Setlur, Anant Achyut; Srivastava, Alok Mani

    2013-04-16

    Disclosed here are methods for the preparation of optionally activated nanocrystalline rare earth phosphates. The optionally activated nanocrystalline rare earth phosphates may be used as one or more of quantum-splitting phosphor, visible-light emitting phosphor, vacuum-UV absorbing phosphor, and UV-emitting phosphor. Also disclosed herein are discharge lamps comprising the optionally activated nanocrystalline rare earth phosphates provided by these methods.

  7. Studies on solid phase synthesis,characterization and fluorescent property of the new rare earth complexes

    Directory of Open Access Journals (Sweden)

    Jianwei SHI

    2015-04-01

    Full Text Available Rare earth-β-diketone ligand complex luminescent material has stable chemical properties and excellent luminous property. Using europium oxide and (γ-NTA as raw materials, novel rare earth-β-dione complexes are synthesized by solid state coordination chemistry. The synthesis temperature and milling time are discussed for optimization. Experimental results show that the suitable reaction situation is at 50 ℃ and 20 h for solid-phase synthesis. The compositions and structures of the complexes are characterized by means of elemental analysis, UV-Vis and FTIR methods, and the phase stability of the complex is determined by using TG-DTA technique. It is proved that preparation of waterless binary rare earth complexes by the solid phase reaction method results in a higher product yield. The fluorescence spectra show that between Eu (Ⅲ and γ-NTA, there exists efficient energy transfer, and the rare earth complexes synthesis is an excellent red bright light-emitting material with excellent UV excited luminescence properties.

  8. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS.

    Science.gov (United States)

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-03-22

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs ((89)Y, (139)La, (140)Ce, (141)Pr, (146)Nd, (147)Sm, (153)Eu, (157)Gd, (159)Tb, (163)Dy, (165)Ho, (166)Er, (169)Tm, (172)Yb and (175)Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001-1.000 μg ∙ L(-1) with r² > 0.997. The limits of detection and quantification for this method were in the range of 0.009-0.010 μg ∙ L(-1) and 0.029-0.037 μg ∙ L(-1), the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg ∙ L(-1)), Ce (1.492 ± 0.995 μg ∙ L(-1)), Nd (0.014 ± 0.009 μg ∙ L(-1)) and Gd (0.023 ± 0.010 μg ∙ L(-1)) among the exposed workers were significantly higher (p elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend than previous reports.

  9. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

    Directory of Open Access Journals (Sweden)

    Yan Li

    2016-03-01

    Full Text Available Rare earth elements (REEs have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1, Ce (1.492 ± 0.995 μg∙L−1, Nd (0.014 ± 0.009 μg∙L−1 and Gd (0.023 ± 0.010 μg∙L−1 among the exposed workers were significantly higher (p < 0.05 than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a

  10. Geochemistry, Nd-Pb Isotopes, and Pb-Pb Ages of the Mesoproterozoic Pea Ridge Iron Oxide-Apatite–Rare Earth Element Deposit, Southeast Missouri

    Science.gov (United States)

    Ayuso, Robert A.; Slack, John F.; Day, Warren C.; McCafferty, Anne E.

    2016-01-01

    Iron oxide-apatite and iron oxide-copper-gold deposits occur within ~1.48 to 1.47 Ga volcanic rocks of the St. Francois Mountains terrane near a regional boundary separating crustal blocks having contrasting depleted-mantle Sm-Nd model ages (TDM). Major and trace element analyses and Nd and Pb isotope data were obtained to characterize the Pea Ridge deposit, improve identification of exploration targets, and better understand the regional distribution of mineralization with respect to crustal blocks. The Pea Ridge deposit is spatially associated with felsic volcanic rocks and plutons. Mafic to intermediate-composition rocks are volumetrically minor. Data for major element variations are commonly scattered and strongly suggest element mobility. Ratios of relatively immobile elements indicate that the felsic rocks are evolved subalkaline dacite and rhyolite; the mafic rocks are basalt to basaltic andesite. Granites and rhyolites display geochemical features typical of rocks produced by subduction. Rare earth element (REE) variations for the rhyolites are diagnostic of rocks affected by hydrothermal alteration and associated REE mineralization. The magnetite-rich rocks and REE-rich breccias show similar REE and mantle-normalized trace element patterns.Nd isotope compositions (age corrected) show that: (1) host rhyolites have ɛNd from 3.44 to 4.25 and TDM from 1.51 to 1.59 Ga; (2) magnetite ore and specular hematite rocks display ɛNd from 3.04 to 4.21 and TDM from 1.6 to 1.51 Ga, and ɛNd from 2.23 to 2.81, respectively; (3) REE-rich breccias have ɛNd from 3.04 to 4.11 and TDM from 1.6 to 1.51 Ga; and (4) mafic to intermediate-composition rocks range in ɛNd from 2.35 to 3.66 and in TDM from 1.66 to 1.56. The ɛNd values of the magnetite and specular hematite samples show that the REE mineralization is magmatic; no evidence exists for major overprinting by younger, crustal meteoric fluids, or by externally derived Nd. Host rocks, breccias, and

  11. Synthesis and characterization of monoclinic rare earth titanates ...

    Indian Academy of Sciences (India)

    Wintec

    to the high cost of reactants and the limitations of upscaling the process. Therefore, such compound oxides are still ... energy saving process (Hwang 2004). Rare earth (RE) titanates are generally prepared by .... decomposition and fuel oxidation take place. Gases such as NO2, H2O and CO2 evolve favouring the forma- ...

  12. Effect of thermally growth oxides (TGO) on adhesion strength for high purity yitria stabilised zirconia (YSZ) and rare - Earth lanthanum zirconates (LZ) multilayer thermal barrier coating before and after isothermal heat treatment

    Science.gov (United States)

    Yunus, Salmi Mohd; Johari, Azril Dahari; Husin, Shuib

    2017-12-01

    Investigation on the effect of Thermally Growth Oxides (TGO) on the adhesion strength for thermal barrier coating (TBC) was carried out. The TBC under studied was the multilayer systems which consist of NiCrAlY bond coat and YSZ/LZ ceramic coating deposited on Ni-based superalloy substrates. The development of thermally growth oxides (TGO) for both TBC systems after isothermal heat treatment was measured. Isothermal heat treatment was carried out at 1100 ˚C for 100 hours to age the samples. ASTM D4541: Standard Test Method for Pull-off Strength of Coatings using Portable Adhesion Tester was used to measure the adhesion strength of both TBC systems before and after heat treatment. The effect of the developed TGO on the measured adhesion strength was examined and correlation between them was established individually for both TBC systems. The failure mechanism of the both system was also identified; either cohesive or adhesive or the combination of both. The results showed that TGO has more than 50% from the bond coat layer for rare-earth LZ system compared to the typical YSZ system, which was less than 10 % from the bond coat layer. This leads to the lower adhesion strength of rare-earth LZ coating system compared to typical YSZ system. Failure mechanism during the pull-off test also was found to be different for both TBC systems. The typical YSZ system experienced cohesive failure whereas the rare-earth LZ system experienced the combination of cohesive and adhesive failure.

  13. Alaska's rare earth deposits and resource potential

    Science.gov (United States)

    Barker, James C.; Van Gosen, Bradley S.

    2012-01-01

    Alaska’s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ‘green’ energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010).

  14. Recycling of Rare Earth Elements

    Science.gov (United States)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

    Any development of an effective process for rare earth (RE) recycling has become more and more challenging, especially in recent years. Since 2011, when commodity prices of REs had met their all-time maximum, prices have dropped rapidly by more than 90 %. An economic process able to offset these fluctuations has to take unconventional methods into account beside well-known strategies like acid/basic leaching or solvent extraction. The solid-state chlorination provides such an unconventional method for mobilizing RE elements from waste streams. Instead of hydrochloric acid this kind of chlorination decomposes NH4Cl thermally to release up to 400 °C hot HCl gas. After cooling the resulting solid metal chlorides may be easily dissolved in pH-adjusted water. Without producing strongly acidic wastes and with NH4Cl as cheap source for hydrogen chloride, solid-state chlorination provides various advantages in terms of costs and disposal. In the course of the SepSELSA project this method was examined, adjusted and optimized for RE recycling from fluorescent lamp scraps as well as Fe14Nd2B magnets. Thereby many surprising influences and trends required various analytic methods to examine the reasons and special mechanisms behind them.

  15. Rare Earth Elements - A New Challenge for the World Economy

    Directory of Open Access Journals (Sweden)

    Cristina Bumbac

    2013-01-01

    Full Text Available Rare Earth Elements or Rare Earth Metals (REM are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium and fifteen lanthanides. The term "rare earth" arises from the rare earth minerals from which they were first isolated. They are uncommon oxide-type minerals (earths found in Gandolinite extracted from one mine in Sweden. The first discovery was made in 1794, but it was only in 1940 that the scientist Frank Spedding developed an ion exchange procedure for separating and purifying the REM. For the next decades, they were hardly used in some "minor" industrial fields. Only after 2000 their importance grew, once the multitude of possibilities to use them was discovered due to technological progress. Now REM are incorporated into almost all modern technological devices: superconductors, magnets, electronic polishers, refining catalysts hybrid car components and military techniques. They are used in small quantities, but due to their extraordinary properties the prices are very high. The main problem is that China dominates this market, with 97% of total global supply. The highest concentration of rare earth metals are in Inner Mongolia in China, Mountain Pass in California U.S.A. and in Mount Weld in Australia. The developed countries are far behind China regarding production and are indeed depending on Chinese exports. Hence, there is a difficult situation on this particular market, with an uncertain future.

  16. Elaboration, structural and spectroscopic properties of rare earth-doped yttrium-hafnium sol-gel oxide powders for scintillation applications

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva-Ibanez, M.; Le Luyer, C.; Dujardin, C.; Mugnier, J

    2003-12-15

    Hafnium dioxide (HfO{sub 2}) presents a high crystalline density ({approx}10 g/cm{sup 3}) which makes it attractive for host lattice activated by rare earths (RE) for applications as scintillating materials. The potentiality to prepare Eu{sup 3+} and Tb{sup 3+} activated HfO{sub 2} sol-gel powders, with high scintillation yield, is explored. The powders are heat-treated at 1000 deg. C before analyses. The incorporation of yttrium (Y{sup 3+}) in various concentrations is conducted to vary the lattice phase and to stabilize the trivalent terbium ions. The influence of Y{sup 3+} on the microstructure and then on the scintillation properties of the material is presented. A high concentration of Y{sup 3+} (20 mol%) stabilizes pure HfO{sub 2} tetragonal phase whatever RE (1 mol%) doping. The powders with the highest relative scintillation yield are Eu{sup 3+}:HfO2 without Y{sup 3+} incorporation and crystallized into the monoclinic phase and Y{sup 3+} (20 mol%): Tb{sup 3+}:HfO2 crystallized into the tetragonal phase. Sequential energy transfer process is assumed to explain these results.

  17. Rare earth ion controlled crystallization of mica glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Garai, Mrinmoy; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in

    2016-09-05

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO{sub 2}, Nd{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} doped K{sub 2}O−MgO−B{sub 2}O{sub 3}−Al{sub 2}O{sub 3}−SiO{sub 2}−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm{sup −3}) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T{sub g}) and crystallization temperature (T{sub c}). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg{sub 3}(AlSi{sub 3}O{sub 10})F{sub 2} by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10{sup −6}/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque

  18. Rare earth elements and strategic mineral policy

    NARCIS (Netherlands)

    Kooroshy, J.; Korteweg, R.; Ridder, M. de

    2010-01-01

    Newspapers report almost daily on international tensions around ‘strategic’ or ‘critical’ minerals such as rare earth elements. The temporary freeze of rare earth exports from China to Japan in late 2010 in retaliation of the capture of a Chinese captain is but one example of the strategic use of

  19. Synthesis and characterization of monoclinic rare earth titanates ...

    Indian Academy of Sciences (India)

    Rare earth titanates; SHS; phase pure RE2Ti2O7; inorganic activator; MW dielectrics; ... the oxide/nitrate precursors using an inorganic compound, ammonium acetate, in place of the general type of organic activators such as urea, alanine etc.

  20. Page 1 Solubility of Rare Earth Hydroxides in Aqueous Sodium ...

    Indian Academy of Sciences (India)

    Solubility of Rare Earth Hydroxides in Aqueous Sodium Potassium Tartrate 317 undissolved after treatment with Rochelle Salt solution. The quantity measured was the weight of oxide in the filtrate. This was done by igniting the precipitated oxalate and also by titrating its sulphuric acid solution against standard potassium ...

  1. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    OpenAIRE

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near ...

  2. Super-resolution microscopy of single rare-earth emitters

    OpenAIRE

    Kolesov, R.; Lasse, S.; Rothfuchs, C.; Wieck, A. D.; Xia, K.; Kornher, T.; Wrachtrup, J.

    2017-01-01

    We demonstrate super-resolution imaging of single rare-earth emitting centers, namely, trivalent cerium, in yttrium aluminum garnet (YAG) crystals by means of stimulated emission depletion (STED) microscopy. The achieved all-optical resolution is $\\approx$ 80nm. Similar results were obtained on H3 color centers in diamond with resolution of $\\approx$ 60nm. In both cases, STED resolution is improving slower than the inverse square-root of the depletion beam intensity. This is caused by excited...

  3. Rare Earth Metals: Resourcefulness and Recovery

    Science.gov (United States)

    Wang, Shijie

    2013-10-01

    When we appreciate the digital revolution carried over from the twentieth century with mobile communication and the Internet, and when we enjoy our high-tech lifestyle filled with iDevices, hybrid cars, wind turbines, and solar cells in this new century, we should also appreciate that all of these advanced products depend on rare earth metals to function. Although there are only 136,000 tons of annual worldwide demand, (Cho, Rare Earth Metals, Will We Have Enough?)1 rare earth metals are becoming such hot commodities on international markets, due to not only to their increasing uses, including in most critical military hardware, but also to Chinese growth, which accounts for 95% of global rare earth metal production. Hence, the 2013 technical calendar topic, planned by the TMS/Hydrometallurgy and Electrometallurgy Committee, is particularly relevant, with four articles (including this commentary) contributed to the JOM October Issue discussing rare earth metals' resourcefulness and recovery.

  4. Magnetic Partitioning Nanofluid for Rare Earth Extraction from Geothermal Fluids

    Energy Technology Data Exchange (ETDEWEB)

    McGrail, Bernard P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Jian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nune, Satish K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-08-21

    Rare earth metals are critical materials in a wide variety of applications in generating and storing renewable energy and in designing more energy efficient devices. Extracting rare earth metals from geothermal brines is a very challenging problem due to the low concentrations of these elements and engineering challenges with traditional chemical separations methods involving packed sorbent beds or membranes that would impede large volumetric flow rates of geothermal fluids transitioning through the plant. We are demonstrating a simple and highly cost-effective nanofluid-based method for extracting rare earth metals from geothermal brines. Core-shell composite nanoparticles are produced that contain a magnetic iron oxide core surrounded by a shell made of silica or metal-organic framework (MOF) sorbent functionalized with chelating ligands selective for the rare earth elements. By introducing the nanoparticles at low concentration (≈0.05 wt%) into the geothermal brine after it passes through the plant heat exchanger, the brine is exposed to a very high concentration of chelating sites on the nanoparticles without need to pass through a large and costly traditional packed bed or membrane system where pressure drop and parasitic pumping power losses are significant issues. Instead, after a short residence time flowing with the brine, the particles are effectively separated out with an electromagnet and standard extraction methods are then applied to strip the rare earth metals from the nanoparticles, which are then recycled back to the geothermal plant. Recovery efficiency for the rare earths at ppm level has now been measured for both silica and MOF sorbents functionalized with a variety of chelating ligands. A detailed preliminary techno-economic performance analysis of extraction systems using both sorbents showed potential to generate a promising internal rate of return (IRR) up to 20%.

  5. A study on the Deactivation of Usy Zeolites with Different Rare Earth Contents

    Directory of Open Access Journals (Sweden)

    Henriques C.A.

    1998-01-01

    Full Text Available The deactivation of USY zeolites with different rare earth contents due to the coke formed from n-heptane at 450oC was studied. The results show that the presence of rare earth elements decreases the cracking and coking activities, increasing catalytic stability. However, reaction selectivity was not significantly influenced. The greater the rare earth content, the lower the coking rates and the coke contents. The TPO/DSC profiles suggested that the catalytic effect of the rare earth elements promoted coke oxidation.

  6. Surface Disturbance Analysis in Rare Earth Mining

    Science.gov (United States)

    Li, H. K.; Yang, L.; Liu, Z. W.

    2017-02-01

    Mining ion-type rare-earth ore made the landscape and ecological environment degraded in mining area, and the tailing produced by rare-earth mining also led large areas land desertification, which resulted in surface temperature variations and significant differences in other types of mining disturbances. In order to analyse surface disturbance of rare-earth mining area, this paper applied the methods based on Normalized Difference Vegetation Index (NDVI) and Temperature different Coefficient (TDC) as the ecological disturbance indicator, compared and validated their applicability in Lingbei rare-earth mining area of Southern China. The results illustrated that, compared to NDVI, the TDC which reflected the characteristic of rare-earth mining technology has better discrimination of disturbance, especially for in-situ leach mining area. The places of tailing and the in-situ leach mining plants were the most dramatic mining disturbance. They had the biggest TDC value, followed by orchards and farmlands, reclamation plants, they had relatively small disturbance. And the last was the plant with the smallest TDC value. TDC in rare-earth mining could better correspond to the level of surface ecological disturbance. Therefore, TDC as the indicator of ecological disturbance factor had better performance than NDVI in rare-earth mining area.

  7. Rare earth element mines, deposits, and occurrences

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset contains location, geologic and mineral economic data for world rare earth mines, deposits, and occurrences. The data in this compilation were derived...

  8. Rare earth elements in nuclear medicine

    Directory of Open Access Journals (Sweden)

    Kodina G.E.

    2014-12-01

    Full Text Available The review focuses on the key applications of stable and radioactive isotopes of rare earth elements in the technology of nuclear medicine, radionuclide diagnostics and therapy, as well as magnetic resonance imaging and binary radiotherapy technologies.

  9. PETROLOGY AND RARE EARTH ELEMENTS (REE ...

    African Journals Online (AJOL)

    USER

    LTD PRINTED IN NIGERIA. ISSN 1596-6798 www.globaljournalseries.com, Email: info@globaljournalseries.com. PETROLOGY AND RARE EARTH ELEMENTS (REE) DISTRIBUTION. PATTERNS OF MAGMATIC ROCKS IN GBOKO AREA, LOWER. BENUE TROUGH NIGERIA: IMPLICATION FOR TECTONIC. EVOLUTION.

  10. Electronic Structure of Rare-Earth Metals. II. Positron Annihilation

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    The angular correlation of the photons emitted when positrons annihilate with electrons has been studied in single crystals of the rare-earth metals Y, Gd, Tb, Dy, Ho, and Er, and in a single crystal of an equiatomic alloy of Ho and Er. A comparison of the results for Y with the calculations...... of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood...... surface normal to the c axis. The same aspects of the Fermi surface are believed to be important in determining the stability of the periodic magnetic structures formed in some of the metals, and there is a strong correlation between the structure in the angular distribution and the magnetic properties...

  11. Ternary rare earth-lanthanide sulfides

    Science.gov (United States)

    Takeshita, Takuo; Gschneidner, Jr., Karl A.; Beaudry, Bernard J.

    1987-01-06

    A new ternary rare earth sulfur compound having the formula: La.sub.3-x M.sub.x S.sub.4 where M is a rare earth element selected from the group europium, samarium and ytterbium and x=0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000.degree. C.

  12. Adsorbate-modified growth of ultrathin rare-earth oxide films on silicon and complementary studies of cerium oxide on ruthenium; Adsorbat-modifiziertes Wachstum ultraduenner Seltenerdoxid-Filme auf Silizium und komplementaere Studien von Ceroxid auf Ruthenium

    Energy Technology Data Exchange (ETDEWEB)

    Kaemena, Bjoern

    2013-11-27

    Rare-earth oxides (REOx) are extensively investigated due to their extraordinary physical and chemical properties, which essentially arise from the unfilled 4f electron shell, in order to reveal the nature of these exceptional properties and ultimately to utilize them for multiple technological applications. To maintain the exponential increase in integration density in CMOS technology, which is also known as Moore s law, there is a strong desire for ultrathin, well-ordered, epitaxial REOx layers with a precisely engineered interface, which is essential for reliable, ultrahigh-performance devices. So far this has been considerably impeded by RE-promoted silicon oxidation, leading to amorphous silicon oxide and RE silicon formation. By using complementary synchrotron radiation methods such as X-ray standing waves (XSW), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), structural and spectroscopic information are inferred simultaneously from ultrathin ceria and lanthana films grown on chlorine, silver and gallium passivated silicon(111). In general, it is revealed that the chemical and structural composition of the interface and the crystallinity of ultrathin REOx layers on silicon can be precisely controlled by adsorbate-mediated growth. This might represent a crucial step towards a perfectly engineered interface, eventually allowing for the integration of REOx as high-k gate oxides in microelectronics. In catalysis inverse model catalysts are studied with the aim of getting an in-depth understanding of the basic principles of catalysis. These model systems are employed to study, e. g., the nature of active sites and the reaction pathways in complex catalytic converters. However, a lot remains unknown about the chemical activity and selectivity as a function of the growth mechanism, structure and morphology of these model systems. The powerful spectroscopic photoemission and low-energy electron microscope, which is able to reveal the surface

  13. Rare earth element ore geology of carbonatites

    Science.gov (United States)

    Verplanck, Philip L.; Mariano, Anthony N.; Mariano, Anthony

    2016-01-01

    For nearly 50 years, carbonatites have been the primary source of niobium and rare earth elements (REEs), in particular the light REEs, including La, Ce, Pr, and Nd. Carbonatites are a relatively rare type of igneous rock composed of greater than 50 vol % primary carbonate minerals, primarily calcite and/or dolomite, and contain the highest concentrations of REEs of any igneous rocks. Although there are more than 500 known carbonatites in the world, currently only four are being mined for REEs: the Bayan Obo, Maoniuping, and Dalucao deposits in China, and the Mountain Pass deposit in California, United States. The carbonatite-derived laterite deposit at Mount Weld in Western Australia is also a REE producer. In addition to REEs, carbonatite-related deposits are the primary source of Nb, with the Araxá deposit, a carbonatite-derived laterite in Minas Gerais state, Brazil, being the dominant producer. Other commodities produced from carbonatite-related deposits include phosphates, iron, fluorite, copper, vanadium, titanium, uranium, and calcite.Types of ores include those formed as primary magmatic minerals, from late magmatic hydrothermal fluids, and by supergene enrichment in weathered horizons. Although the principal REE-bearing mineral phases include fluorocarbonates (bastnäsite, parisite, and synchysite), hydrated carbonates (ancylite), and phosphates (monazite and apatite), the dominant mineral exploited at most mines is bastnäsite. Bastnäsite typically is coarse grained and contains approximately 75 wt % RE2O3 (rare earth oxides; REOs). Processes responsible for REE enrichment include fractional crystallization of the carbonatitic magma, enrichment of REEs in orthomagmatic or hydrothermal fluids and subsequent precipitation or subsolidus metasomatic redistribution of REEs, and breakdown of primary carbonatitic mineral phases by chemical weathering and sequestration of REEs in secondary minerals or in association with clays. Carbonatites are primarily

  14. Structures and stabilities of trivalent and tetravalent rare earth ions in sevenfold and eightfold coordination in fluorite-related complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Morss, L.R.

    1991-12-31

    This paper reports the preparation and characterization of a series of oxides containing 3+ or 4+ lanthanide (M = Ce, Pr, or Tb) ions, with different ionic sizes and varying M{sup 4+}/M{sup 3+} reduction potentials, in nearly cubic coordination. The objective of the study was to demonstrate how oxidation-reduction characteristics and ionic size trends explain the properties of these oxides and to compare the oxidation-reduction stability of M{sup 3+} and M{sup 4+} lanthanide ions in high (CN 7 or 8) coordination in fluorite-related oxides versus low (CN 6) coordination in perovskite oxides. Efficient preparative methods are reported, as well as powder diffraction and thermogravimetric measurements for oxides CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x}. These oxides were characterized by X-ray powder diffraction and by thermogravimetric analysis. CaCeTi{sub 2}O{sub 7} is a pyrochlore, a = 10.142(4) {Angstrom}, with Ce{sup 4+} much more easily reducible than in the perovskite BaCeO{sub 3}. By contrast, a preparation with the stoichiometry ``CaPbTi{sub 2}O{sub 7-x}`` is a two-phase mixture-of perovskite CaTiCo{sub 3} and a presumably Pr{sup 3+}-rich pyrochlore Pr{sub 2}Ti{sub 2}O{sub 7}(?). CaTbTi{sub 2}O{sub 7-x} appears to be a Tb{sup 3+} pyrochlore, a = 10.149(2) {Angstrom}. CaCeZr{sub 2}O{sub 7} is a pyrochlore, a = 10.524(1) {Angstrom}. A preparation of ``CaPbZr{sub 2}O{sub 7-x}`` also appeared to yield a two-phase mixture, perovskite CaZrO{sub 3} and pyrochlore Pr{sub 2}Zr{sub 2}O{sub 7}. In this paper, the structures, f-element ion sites, and M(4)-M(3) stability trends in the CaMTi{sub 2}O{sub 7-x} and CaMZr{sub 2}O{sub 7-x} oxides are compared with the structural and stability trends in the perovskites BaMO{sub 3} which have M{sup 4+} ions in sixfold (tilted octahedra) coordination.

  15. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

    Ott, Ryan T.; McCallum, Ralph W.; Jones, Lawrence L.

    2017-08-08

    A method of treating rare earth metal-bearing permanent magnet scrap, waste or other material in a manner to recover the heavy rare earth metal content separately from the light rare earth metal content. The heavy rare earth metal content can be recovered either as a heavy rare earth metal-enriched iron based alloy or as a heavy rare earth metal based alloy.

  16. Use of Radioactive Ion Beams for Biomedical Research 2. in-vivo dosimetry using positron emitting rare earth isotopes with the rotating prototype PET scanner at the Geneva Cantonal Hospital

    CERN Multimedia

    2002-01-01

    % IS331 \\\\ \\\\ The use of radioactive metal ions (such as $^{90}$Y, $^{153}$Sm or $^{186}$Re) in cancer therapy has made some progress, but has been hampered by factors that could be addressed at CERN with a greater likelihood of success than at any other installation in the world. The present proposal seeks to use the unique advantage of CERN ISOLDE to get round these problems together with the PET scanners at the Cantonal Hospital Geneva (PET~=~positron emission tomography). Radioisotope production by spallation at ISOLDE makes available a complete range of isotopes having as complete a diversity of types and energy of radiation, of half-life, and of ionic properties as one would wish. Among these isotopes several positron-emitters having clinical relevance are available.\\\\ \\\\Some free rare earth chelatas are used presently in palliation of painful bone metastases. Curative effects are not able for the moment with this kind of radiopharmaceuticals. More and better data on the biokinetics and bio-distribution...

  17. Research on determination of the rare-earth content in metal phases of steel

    Science.gov (United States)

    Keming, Fang; Ruiming, Ni

    1986-02-01

    The behavior of the rare-earth dissolved in a-Fe, of the iron-cerium intermetallic compounds and of the rare-earth inclusions in electrolytic separation process has been studied by means of counting measurements of radioactivity, the electron probe, and X-ray analysis. The experimental results show that the rare-earth sulfide and the rare-earth oxide are stable completely in the electrolytic separation process, when the composition of the electrolytic solution is 1 pct 4-methyl ammonium chloride, 5 pct triethanolamine, 5 pct glycerin, and 89 pct methyl alcohol, and the controlling anode current density is ≤100 mA/cm2. But Fe-Ce intermetallic compounds and the rare-earth dissolved in a-Fe enter into electrolytic solution as ions. When the cerium ion concentration in electrolytic solution is >7.87 X 10-5 mol/liter electrolyte, precipitates of cerium hydroxide will be formed. When the inclusions are separated quantitatively, the electrolytic solution must be filtered by using a funnel with filter paper pulp thick up to 6 mm, and not be filtered directly with single filter paper. Samples without rare-earth were remelted and a radioactive isotope141Ce was added to the steel. Inclusions were separated by the electrolytic method in the nonaqueous solution. The counting of 14lCe in the electrolytic solution was measured. Thus the rare-earth content in the metal phases can be calculated. Experimental results show that the rare-earth content in the metal phases increases with the total rare-earth content in steel. The rare-earth content in the metal phases of the steel was also found to increase as the aluminum content in steel was increased. This method for determining the rare-earth content in the metal phases of steel is very sensitive. The sensitivity is 10-6 pct.

  18. Precursors for MOCVD and ALD of rare earth oxides-complexes of the early lanthanides with a donor-functionalized alkoxide ligand.

    Science.gov (United States)

    Aspinall, Helen C; Bickley, Jamie F; Gaskell, Jeffrey M; Jones, Anthony C; Labat, Gael; Chalker, Paul R; Williams, Paul A

    2007-07-23

    Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp = HOCMe(2)CH(2)OMe, 1-methoxy-2-methylpropan-2-ol) are excellent precursors for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of lanthanide oxides; however, their coordination chemistry, which is the subject of this paper, is rather complex. Precursors for MOCVD and ALD of lanthanide oxides are prepared by the reaction of [Ln{N(SiMe(3))(2)}(3)] with 3 equiv of the alcohol Hmmp in toluene in the presence of 1 equiv of tetraglyme and are indefinitely stable in solution. Reaction of [Ln{N(SiMe(3))(2)}(3)] with 3 equiv of Hmmp in the absence of stabilizing Lewis bases gives complex condensed products with empirical formula [{Ln(mmp)(3-n)}(2)O(n)]. These condensed products show poor volatility and are unsatisfactory precursors for MOCVD or ALD of oxides. The cluster complex [La(3)(mu(3),kappa(2)-mmp)(2)(mu(2),kappa(2)-mmp)(3)(mmp)(4)] has been prepared by careful reaction of [La{N(SiMe(3))(2)}(3)] with 4 equiv of Hmmp and has been characterized by single-crystal X-ray diffraction. Salt metathesis reactions using M(mmp) (M = Li or Na) are unreliable routes to [Ln(mmp)(3)]. Crystals of the heterometallic cluster complex [NaLa(3)(mu(3)-OH)(mu(3),kappa(2)-mmp)(2)(mu(2),kappa(2)-mmp)(4)(mmp)(3)] were isolated from the reaction of [La(NO(3))(3)(tetraglyme)] with 3 equiv of Na(mmp), and crystals of [Li(kappa(2)-Hmmp)Pr(mu(2),eta(2)-mmp)(4))LiCl] were isolated from the reaction of PrCl(3) with 3 equiv of Li(mmp); both of these complexes have been characterized by single-crystal X-ray diffraction.

  19. China’s Rare Earths Supply Forecast in 2025: A Dynamic Computable General Equilibrium Analysis

    Directory of Open Access Journals (Sweden)

    Jianping Ge

    2016-09-01

    Full Text Available The supply of rare earths in China has been the focus of significant attention in recent years. Due to changes in regulatory policies and the development of strategic emerging industries, it is critical to investigate the scenario of rare earth supplies in 2025. To address this question, this paper constructed a dynamic computable equilibrium (DCGE model to forecast the production, domestic supply, and export of China’s rare earths in 2025. Based on our analysis, production will increase by 10.8%–12.6% and achieve 116,335–118,260 tons of rare-earth oxide (REO in 2025, based on recent extraction control during 2011–2016. Moreover, domestic supply and export will be 75,081–76,800 tons REO and 38,797–39,400 tons REO, respectively. The technological improvements on substitution and recycling will significantly decrease the supply and mining activities of rare earths. From a policy perspective, we found that the elimination of export regulations, including export quotas and export taxes, does have a negative impact on China’s future domestic supply of rare earths. The policy conflicts between the increase in investment in strategic emerging industries, and the increase in resource and environmental taxes on rare earths will also affect China’s rare earths supply in the future.

  20. Analysis of electrical and microstructural characteristics of a ZnO-based varistor doped with rare earth oxide; Analise das caracteristicas microestruturais e eletricas de um varistor a base de ZnO dopado com oxidos de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, J.M. de; Dias, R.; Furtado, J.G. de M. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Assuncao, F.C.R. [Pontificia Univ. Catolica do Rio de Janeiro (PUC/Rio), RJ (Brazil)

    2010-07-01

    Varistor is a semiconductor device, used in the protection of electrical systems, characterized to have a high no-linear electric resistance. Its properties are directly dependents of its chemical composition and microstructural characteristics. In this work were analyzed microstructural and electrical characteristics of a ZnO-based varistor doped with rare earth oxide, with chemical composition (mol%) 98,5.ZnO - 0,3.Pr{sub 6}O{sub 11} - 0,2.Dy{sub 2}O{sub 3} - 0,9.Co{sub 2}O{sub 3} - 0,1.Cr{sub 2}O{sub 3}. X-ray diffraction for phase characterization, scanning electron microscopy and energy dispersive X-ray spectroscopy were used for microstructural analysis. Measurement of average grain size and electrical and dielectric characteristics complete the characterization. The results show the formation of biphasic microstructure and with high densification, presenting relevant varistors characteristics but that would need improvements.(author)

  1. Determination of trace/ultratrace rare earth elements in environmental samples by ICP-MS after magnetic solid phase extraction with Fe3O4@SiO2@polyaniline-graphene oxide composite.

    Science.gov (United States)

    Su, Shaowei; Chen, Beibei; He, Man; Hu, Bin; Xiao, Zuowei

    2014-02-01

    A novel Fe3O4@SiO2@polyaniline-graphene oxide composite (MPANI-GO) was prepared through a simple noncovalent method and applied to magnetic solid phase extraction (MSPE) of trace rare earth elements (REEs) in tea leaves and environmental water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The prepared MPANI-GO was characterized by transmission electron microscopy and vibrating sample magnetometer. Various parameters affecting MPANI-GO MSPE of REEs have been investigated. Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.04-1.49 ng L(-1) and the relative standard deviations (RSDs, c=20 ng L(-1), n=7) were 1.7-6.5%. The accuracy of the proposed method was validated by analyzing a Certified Reference Material of GBW 07605 tea leaves. The method was also successfully applied for the determination of trace REEs in tea leaves and environmental water samples. The developed MPANI-GO MSPE-ICP-MS method has the advantages of simplicity, rapidity, high sensitivity, high enrichment factor and is suitable for the analysis of trace REEs in samples with complex matrix. © 2013 Elsevier B.V. All rights reserved.

  2. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    Unknown

    CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to ...

  3. Magnetic excitations in rare earth systems

    Science.gov (United States)

    Jensen, Jens

    1982-10-01

    The observation of magnetic excitations, by means of inelastic neutron scattering, provides valuable information on the magnetic forces acting in rare-earth systems. The RPA (random-phase approximation) theory, developed into its final form in the early seventies, is now a widely used tool for analyzing the excitation spectra in systems with well-defined local moments. These excitations reflect both the dynamics of the single moments and the interactions of these moments with their surroundings. A discussion of the information which has been obtained from studies of the magnetic excitations in the rare-earth metal is presented. The emphasis is laid on Pr-metal which has attracted much interest in recent years. Recent progress in the investigation of rare-earth intermetallic compounds, like the Laves-phase and the CsCl-type-compounds and the rare-earth pnictides, is also condidered. Some aspects of the magnetic properties of the actinides can be understood in terms of a model of localized moments, and we include a discussion of USb, where the spin-wave spectrum contains direct evidence that the spins are ordered in a triple- q structure. The magnetic excitations may be coupled to the phonons and in the metallic systems they interact with the electron- hole excitations of the conduction electrons. Therefore the sound velocities and the effective mass of the conduction electrons can be strongly affected by the spin system. Recent developments within these areas are also reviewed.

  4. Non-rare earth magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, Everett E.; Huba, Zachary J.; Carroll, Kyler J.; Farghaly, Ahmed; Khanna, Shiv N.; Qian, Meichun; Bertino, Massimo

    2017-09-26

    Continuous flow synthetic methods are used to make single phase magnetic metal alloy nanoparticles that do not contain rare earth metals. Soft and hard magnets made from the magnetic nanoparticles are used for a variety of purposes, e.g. in electric motors, communication devices, etc.

  5. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of ...

  6. Rare Earth Fluorescent Nanomaterials for Enhanced Development of Latent Fingerprints.

    Science.gov (United States)

    Wang, Meng; Li, Ming; Yu, Aoyang; Wu, Jian; Mao, Chuanbin

    2015-12-30

    The most commonly found fingerprints at crime scenes are latent and, thus, an efficient method for detecting latent fingerprints is very important. However, traditional developing techniques have drawbacks such as low developing sensitivity, high background interference, complicated operation, and high toxicity. To tackle this challenge, we have synthesized two kinds of rare earth fluorescent nanomaterials, including the fluoresce red-emitting YVO4:Eu nanocrystals and green-emitting LaPO4:Ce,Tb nanobelts, and then used them as fluorescent labels for the development of latent fingerprints with high sensitivity, high contrast, high selectivity, high efficiency, and low background interference, on various substrates including noninfiltrating materials, semi-infiltrating materials, and infiltrating materials.

  7. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...... to account for all alloys except the Sc based. The exceptional behavior of the Sc alloys is due to a low density of states for Sc. A brief discussion is given of the effect on the mean-field results of changes in volume or c/a ratio and of critical fluctuations. Since the physical mechanisms of these ideal...

  8. SEPARATION OF RARE EARTHS BY SOLVENT EXTRACTION

    Science.gov (United States)

    Peppard, D.F.; Mason, G.W.

    1960-10-11

    A process is given for separating lanthanide rare earths from each other from an aqueous mineral acid solution, e.g., hydrochloric or nitric acid of a concentration of above 3 M, preferably 12 to 16 M, by extraction with a water- immiscible alkyl phosphate, such as tributyl phosphate or a mixture of mono-, di- and tributyl phosphate, and fractional back-extraction with mineral acid whereby the lanthanides are taken up by the acid in the order of increasing atomic number.

  9. Tens of micron-sized unilamellar nanosheets of Y/Eu layered rare-earth hydroxide: efficient exfoliation via fast anion exchange and their self-assembly into oriented oxide film with enhanced photoluminescence

    Science.gov (United States)

    Zhu, Qi; Li, Ji-Guang; Li, Xiaodong; Sun, Xudong; Qi, Yang; Zhu, Miaoyong; Sakka, Yoshio

    2014-02-01

    Layered rare-earth hydroxide (LRH) crystals of (Y0.95Eu0.05)2(OH)5NO3·nH2O with a lateral size of ˜ 300 μm and a thickness of ˜ 9 μm have been synthesized via a hydrothermal reaction of mixed nitrate solutions in the presence of mineralizer NH4NO3 at 200 °C for 24 h. LRH exhibits the ability to undergo intercalation and anion exchange with DS- (C12H25OSO3-) via hydrothermal treatment. Compared with traditional anion exchange at room temperature, hydrothermal processing not only shortens the anion exchange time from 720 to 24 h but also increases the basal spacing. The arrangements of DS- in the interlayer of LRH are significantly affected by the DS- concentration and reaction temperature, and the basal spacing of the LRH-DS sample in the crystal edge is assumed to be larger than that in the crystal center. A higher DS- concentration and reaction temperature both induce more intercalation of DS- anions into the interlayer gallery, thus yielding a larger basal spacing. Unilamellar nanosheets with a lateral size of ⩾60 μm and a thickness of ˜ 1.6 nm can be obtained by delaminating LRH-DS in formamide. The resultant unilamellar nanosheets are single crystalline. Transparent (Y0.95Eu0.05)2O3 phosphor films with a uniform [111] orientation and a layer thickness of ˜ 90 nm were constructed with the nanosheets as building blocks via spin-coating, followed by proper annealing. The oriented oxide film exhibits a strong red emission at 614 nm (the 5D0-7F2 transition of Eu3+), whose intensity is ˜ 2 times that of the powder form owing to the significant exposure of the (222) facets.

  10. Tens of micron-sized unilamellar nanosheets of Y/Eu layered rare-earth hydroxide: efficient exfoliation via fast anion exchange and their self-assembly into oriented oxide film with enhanced photoluminescence

    Directory of Open Access Journals (Sweden)

    Qi Zhu

    2014-01-01

    Full Text Available Layered rare-earth hydroxide (LRH crystals of (Y0.95Eu0.052(OH5NO3centerdotnH2O with a lateral size of ~ 300 μm and a thickness of ~ 9 μm have been synthesized via a hydrothermal reaction of mixed nitrate solutions in the presence of mineralizer NH4NO3 at 200 °C for 24 h. LRH exhibits the ability to undergo intercalation and anion exchange with DS− (C12H25OSO3− via hydrothermal treatment. Compared with traditional anion exchange at room temperature, hydrothermal processing not only shortens the anion exchange time from 720 to 24 h but also increases the basal spacing. The arrangements of DS− in the interlayer of LRH are significantly affected by the DS− concentration and reaction temperature, and the basal spacing of the LRH-DS sample in the crystal edge is assumed to be larger than that in the crystal center. A higher DS− concentration and reaction temperature both induce more intercalation of DS− anions into the interlayer gallery, thus yielding a larger basal spacing. Unilamellar nanosheets with a lateral size of ≥60 μm and a thickness of ~ 1.6 nm can be obtained by delaminating LRH-DS in formamide. The resultant unilamellar nanosheets are single crystalline. Transparent (Y0.95Eu0.052O3 phosphor films with a uniform [111] orientation and a layer thickness of ~ 90 nm were constructed with the nanosheets as building blocks via spin-coating, followed by proper annealing. The oriented oxide film exhibits a strong red emission at 614 nm (the 5D0–7F2 transition of Eu3+, whose intensity is ~ 2 times that of the powder form owing to the significant exposure of the (222 facets.

  11. Electro-kinetic Separation of Rare Earth Elements Using a Redox-Active Ligand.

    Science.gov (United States)

    Fang, Huayi; Cole, Bren E; Qiao, Yusen; Bogart, Justin A; Cheisson, Thibault; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

    2017-10-16

    Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C6 H4 CH2 }3 N]3- . Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electro-kinetic separation of rare earth elements using a redox-active ligand

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Huayi; Cole, Bren E.; Qiao, Yusen; Bogart, Justin A.; Cheisson, Thibault; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA (United States)

    2017-10-16

    Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C_6H_4CH_2}{sub 3}N]{sup 3-}. Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Ionic liquid technology for recovery and separation of rare earths

    OpenAIRE

    Binnemans, Koen

    2015-01-01

    End-of-life neodymium-iron-boron and samarium-cobalt permanent magnets, fluorescent lamps and metal hydride batteries are valuable secondary resources of rare earths. These resources are characterised by relatively small volumes, but high concentrations of rare earths [1]. On the other hand, industrial process residues such as bauxite residue (red mud) and phosphogypsum contain low concentrations of rare earths, but are available in huge volumes [2]. Recovery of rare earths from end-of-life c...

  14. Enhanced separation of rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Greenhalgh, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Herbst, R. S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Garn, T. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Welty, A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Soderstrom, M. D. [Cytec Solvay Group, Tempe, AZ (United States); Jakovljevic, B. [Cytec Solvay Group, Niagara Falls, ON (Canada)

    2016-09-01

    Industrial rare earth separation processes utilize PC88A, a phosphonic acid ligand, for solvent extraction separations. The separation factors of the individual rare earths, the equipment requirements, and chemical usage for these flowsheets are well characterized. Alternative ligands such as Cyanex® 572 and the associated flowsheets are being investigated at the pilot scale level to determine if significant improvements to the current separation processes can be realized. These improvements are identified as higher separation factors, reduced stage requirements, or reduced chemical consumption. Any of these improvements can significantly affect the costs associated with these challenging separation proccesses. A mid/heavy rare earth element (REE) separations flowsheet was developed and tested for each ligand in a 30 stage mixer-settler circuit to compare the separation performance of PC88A and Cyanex® 572. The ligand-metal complex strength of Cyanex® 572 provides efficient extraction of REE while significantly reducing the strip acid requirements. Reductions in chemical consumption have a significant impact on process economics for REE separations. Partitioning results summarized Table 1 indicate that Cyanex® 572 offers the same separation performance as PC88A while reducing acid consumption by 30% in the strip section for the mid/heavy REE separation. Flowsheet Effluent Compositions PC88A Cyanex® 572 Raffinate Mid REE Heavy REE 99.40% 0.60% 99.40% 0.60% Rich Mid REE Heavy REE 2.20% 97.80% 0.80% 99.20% Liquor Strip Acid Required 3.4 M 2.3 M Table 1 – Flowsheet results comparing separation performance of PC88A and Cyanex® 572 for a mid/heavy REE separation.

  15. Rare earth elements complexation with humic acid

    OpenAIRE

    Pourret, Olivier; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

    2007-01-01

    The binding of rare earth elements (REE) to humic acid (HA) was studied by combining ultrafiltration and Inductively Coupled Plasma Mass Spectrometry techniques. REE­HA complexation experiments were performed at various pH conditions (ranging from 2 to 10.5) using a standard batch equilibration method. Results show that the amount of REE bound to HA strongly increases with increasing pH. Moreover, a Middle-REE (MREE) downward concavity is evidenced by REE distribution patterns at acidic pH. M...

  16. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  17. Rare-Earth-Free Traction Motor: Rare Earth-Free Traction Motor for Electric Vehicle Applications

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-01

    REACT Project: Baldor will develop a new type of traction motor with the potential to efficiently power future generations of EVs. Unlike today’s large, bulky EV motors which use expensive, imported rare-earth-based magnets, Baldor’s motor could be light, compact, contain no rare earth materials, and have the potential to deliver more torque at a substantially lower cost. Key innovations in this project include the use of a unique motor design, incorporation of an improved cooling system, and the development of advanced materials manufacturing techniques. These innovations could significantly reduce the cost of an electric motor.

  18. Thermoelectric transport in rare-earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Ulrike

    2007-07-01

    This work focuses on the thermoelectric transport in rare-earth compounds. The measurements of the thermal conductivity, thermopower, and Nernst coefficient are supplemented by investigations of other quantities as magnetic susceptibility and specific heat. Chapter 2 provides an introduction to the relevant physical concepts. Section 1 of that chapter summarizes the characteristic properties of rare-earth systems; section 2 gives an overview on thermoelectric transport processes in magnetic fields. The applied experimental techniques as well as the new experimental setup are described in detail in Chapter 3. The experimental results are presented in Chapter 4-6, of which each concentrates on a different subject. In Chapter 4, various Eu clathrates and the skutterudite-like Ce{sub 3}Rh{sub 4}Sn{sub 13} are presented, which have been investigated as potential thermoelectric materials for applications. Chapter 5 focusses on the study of the energy scales in the heavy-fermion series Lu{sub 1-x}Yb{sub x}Rh{sub 2}Si{sub 2} and Ce{sub x}La{sub 1-x}Ni{sub 2}Ge{sub 2} by means of thermopower investigations. Chapter 6 is dedicated to the thermoelectric transport properties of the correlated semimetal CeNiSn with special emphasis on the Nernst coefficient of this compound. (orig.)

  19. Alternative value chains for rare earths

    DEFF Research Database (Denmark)

    Machacek, Erika; Fold, Niels

    2014-01-01

    The 2011 peak in rare earth element (REE) prices revealed a vast knowledge gap on the REE-based industry considered to be almost monopolized by Chinese players. A global value chain (GVC) framework is used to provide an understanding of value-adding segments of REE in their transformation from mi...... competence are uncovered. On this basis the significance of alternative Anglo-REE-developer supplies is discussed and positioned in the perspective of Chinese industrial upgrading.......The 2011 peak in rare earth element (REE) prices revealed a vast knowledge gap on the REE-based industry considered to be almost monopolized by Chinese players. A global value chain (GVC) framework is used to provide an understanding of value-adding segments of REE in their transformation from mine...... to market but inquiries on the currently most-advanced company strategies for alternative REE supplies form the cornerstone of this paper. The Anglo-REE deposit developer strategies are aligned with the value-adding segments and different approaches to integration and co-optation of REE processing...

  20. High purity neodymium acetate from mixed rare earth carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos A. da Silva; Rocha, Soraya M. Rizzo da; Vasconcellos, Mari E. de; Lobo, Raquel M.; Seneda, Jose A., E-mail: cqueiroz@ipen.b, E-mail: smrrocha@ipen.b, E-mail: mstela@ipen.b, E-mail: rmlobo@ipen.b, E-mail: jaseneda@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pedreira, Walter dos R., E-mail: walter.pedreira@fundacentro.gov.b [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Sao Paulo, SP (Brazil)

    2011-07-01

    A simple and economical chemical process for obtaining high purity neodymium acetate is discussed. The raw material in the form rare earth carbonate is produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography technique with a strong cationic resin, proper to water treatment, and without the use of retention ions was used for the fractionating of the rare earth elements (REE). In this way, it was possible to obtain 99.9% pure Nd{sub 2}O{sub 3} in yields greater than or equal 80%, with the elution of the REE using ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in pH controlled. The complex of EDTA-neodymium was transformed into neodymium oxide, which was subsequently dissolved in acetic acid to obtain the neodymium acetates. Molecular absorption spectrophotometry was used to monitor the neodymium content during the process and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the neodymium acetates. The typical neodymium acetates obtained contain the followings contaminants in {mu}g g{sup -1}: Sc(5.1); Y (0.9); La (1.0); Ce (6.1); Pr (34,4); Sm (12.8); Eu (1.1); Gd (15.4); Tb (29.3); Dy (5.2), Ho(7.4); Er (14.6); Tm (0.3); Yb (2.5); Lu (1.0). The high purity neodymium acetates obtained from this procedure have been applied, replacing the imported product, in research and development area on rare earth catalysts. (author)

  1. INFLUENCE OF RARE-EARTH DOPING ON THE ELECTRICAL PROPERTIES OF HIGH VOLTAGE GRADIENT ZnO VARISTORS

    Directory of Open Access Journals (Sweden)

    LEI KE

    2013-03-01

    Full Text Available The influence of rare-earth doping on the electrical properties of ZnO varistors was investigated. In a lower doping region, the electrical properties were greatly improved with the increase of rare-earth contents. The highest voltage gradient value of 1968.0 V/mm was obtained with a rare-earth concentration of 0.06 mol. %. The microstructure of samples with different amounts of rare-earth oxides was examined and the notable decrease of grain size was identified as the origin for the increased voltage gradient. The doped rare-earth oxides dissolved at the grain boundaries and the excessive doping reduced the voltage across the single grain/grain boundary from 2.72 V to 0.91 V. The poor electrical properties in a higher doping region resulted from the degeneration of grain boundaries and the decrease of block density.

  2. Phase equilibria and thermodynamic properties of oxide systems on the basis of rare earth, alkaline earth and 3d-transition (Mn, Fe, Co metals. A short overview of

    Directory of Open Access Journals (Sweden)

    V. A. Cherepanov

    2015-12-01

    Full Text Available Review is dedicated studies of phase equilibria in the systems based on rare earth elements and 3d transition metals. It’s highlighted several structural families of these compounds and is shown that many were found interesting properties for practical application, such as high conductivity up to the superconducting state, magnetic properties, catalytic activity of the processes of afterburning of exhaust gases, the high mobility in the oxygen sublattice and more.

  3. Light Emission from Rare-Earth Doped Silicon Nanostructures

    Directory of Open Access Journals (Sweden)

    P. Mascher

    2008-05-01

    Full Text Available Rare earth (Tb or Ce-doped silicon oxides were deposited by electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD. Silicon nanocrystals (Si-ncs were formed in the silicon-rich films during certain annealing processes. Photoluminescence (PL properties of the films were found to be highly dependent on the deposition parameters and annealing conditions. We propose that the presence of a novel sensitizer in the Tb-doped oxygen-rich films is responsible for the indirect excitation of the Tb emission, while in the Tb-doped silicon-rich films the Tb emission is excited by the Si-ncs through an exciton-mediated energy transfer. In the Ce-doped oxygen-rich films, an abrupt increase of the Ce emission intensity was observed after annealing at 1200∘C. This effect is tentatively attributed to the formation of Ce silicate. In the Ce-doped silicon-rich films, the Ce emission was absent at annealing temperatures lower than 1100∘C due to the strong absorption of Si-ncs. Optimal film compositions and annealing conditions for maximizing the PL intensities of the rare earths in the films have been determined. The light emissions from these films were very bright and can be easily observed even under room lighting conditions.

  4. Electronic structure of rare earth bismuthides

    CERN Document Server

    Drzyzga, M; Deniszczyk, J; Michalczewski, T

    2003-01-01

    The electronic structure of rare earth bismuthides - Gd sub 4 Bi sub 3 , Tb sub 4 Bi sub 3 and R sub 5 Bi sub 3 (R = Gd, Tb, Dy, Ho, Er) - has been investigated with use of x-ray and ultraviolet photoelectron spectroscopies and calculated with the tight-binding linear muffin-tin orbital method. The spectra simulated on the basis of ab initio results reproduce correctly the experimental ones. This enabled analysis of the character of the electronic states, their hybridization and influence on magnetic properties. The temperature dependence of the valence band photoemission of ferromagnetic Gd sub 4 Bi sub 3 and Tb sub 4 Bi sub 3 has been studied and compared to the results obtained with the spin-polarized, non-polarized and open core methods of calculation.

  5. Rare earth elements in river waters

    Science.gov (United States)

    Goldstein, Steven J.; Jacobsen, Stein B.

    1988-01-01

    To characterize the input to the oceans of rare earth elements (REE) in the dissolved and the suspended loads of rivers, the REE concentrations were measured in samples of Amazon, Indus, Mississippi, Murray-Darling, and Ohio rivers and in samples of smaller rivers that had more distinct drainage basin lithology and water chemistry. It was found that, in the suspended loads of small rivers, the REE pattern was dependent on drainage basin geology, whereas the suspended loads in major rivers had relatively uniform REE patterns and were heavy-REE depleted relative to the North American Shale composite (NASC). The dissolved loads in the five major rivers had marked relative heavy-REE enrichments, relative to the NASC and the suspended material, with the (La/Yb)N ratio of about 0.4 (as compared with the ratio of about 1.9 in suspended loads).

  6. Determination of trace elements in high pure rare earth oxide by double focusing inductively coupled plasma mass spectrometry (HR ICP-MS) and high performance liquid chromatography (HPLC) techniques; Determinacao de impurezas metalicas em oxidos de terras raras de alta pureza pela espectrometria de massa (setor magnetico) com fonte de plasma induzida por argonio (HR ICP-MS) e cromatografia liquida de alto desempenho (HPLC)

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira Filho, Walter dos Reis

    2000-07-01

    Rare earth oxides are used in several technological fields whose applications can be observed in several areas of modern technology, among which are included: lasers, semiconductors semi, high purity materials and metallic alloys. The field of applications of the rare earth elements is quite wide. Several important industrial applications are ceramics, catalysts and metallurgical as well as research areas and high technology sectors. Such applications have been presenting an accentuated growth in the last years. Chemical characterization of rare earth oxides of high purity has been constituting one of the major challenges of analytical chemistry. Several analytical techniques were used for chemical characterization of high purity rare earth the oxides. Even so, those techniques present limitations when one needs to characterize materials of a high level of purity, as in the case of rare earth oxides. Some of those limitations are associated, for example, to spectral interference. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a powerful analytical tool for quantitative analysis of metal impurities in high purity materials. The Instituto de Pesquisas Energeticas e Nucleares (IPEN) has an unit of production and purification of rare earth oxides, with above 99,9% level of purity. In this work, the rare earth impurities were characterized in samples (La{sub 2}O{sub 3}; CeO{sub 2}; Pr{sub 6}O{sub 11}; Nd{sub 2}O{sub 3}; Sm{sub 2}O{sub 3}; Gd{sub 2}O{sub 3}; Y{sub 2}O{sub 3}) produced at the IPEN and certified standard materials produced by Johnson Matthey Chemical (JMC). The technique of high performance liquid chromatography (HPLC) was used in the separation of the impurities. Quantification of metallic impurities was carried out as inductively coupled plasma mass spectrometer (HR-ICP MS). In this work it is presented a new analytical methodology in the chemical characterization of metallic impurities in rare earth oxides of high purity (> 99,9%) with and

  7. Enhanced pinning in mixed rare earth-123 films

    Science.gov (United States)

    Driscoll, Judith L [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

    2009-06-16

    An superconductive article and method of forming such an article is disclosed, the article including a substrate and a layer of a rare earth barium cuprate film upon the substrate, the rare earth barium cuprate film including two or more rare earth metals capable of yielding a superconductive composition where ion size variance between the two or more rare earth metals is characterized as greater than zero and less than about 10.times.10.sup.-4, and the rare earth barium cuprate film including two or more rare earth metals is further characterized as having an enhanced critical current density in comparison to a standard YBa.sub.2Cu.sub.3O.sub.y composition under identical testing conditions.

  8. Rare-Earth nanoparticles with enhanced upconversion emission and suppressed rare-Earth-ion leakage.

    Science.gov (United States)

    Wang, Ye-Fu; Sun, Ling-Dong; Xiao, Jia-Wen; Feng, Wei; Zhou, Jia-Cai; Shen, Jie; Yan, Chun-Hua

    2012-04-27

    Upconversion emissions from rare-earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF(4):Yb,Er@CaF(2) nanoparticles (NPs) with a small size (10-13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF(2) shell protects the rare-earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF(4):Yb,Er@CaF(2) NPs, HeLa cells were imaged with low background interference. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The Strategic Implications of China's Rare Earths Policy

    Directory of Open Access Journals (Sweden)

    Shane Bilsborough

    2012-08-01

    Full Text Available Drawing on literature in China studies, strategic theory, and expert interviews, this article analyzes the possibility of "rare earths" being leveraged by the People's Republic of China (PRC in a crisis. The evidence suggests China's position in the rare earths market could constitute a significant security liability for the United States. It also seems that even if coercion fails to materialize, China's rare earths policies have the potential to intensify security dilemmas in Sino-American relations.

  10. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  11. Rare earth-ruthenium-magnesium intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Sebastian; Kersting, Marcel; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2017-07-01

    Eight new intermetallic rare earth-ruthenium-magnesium compounds have been synthesized from the elements in sealed niobium ampoules using different annealing sequences in muffle furnaces. The compounds have been characterized by powder and single crystal X-ray diffraction. Sm{sub 9.2}Ru{sub 6}Mg{sub 17.8} (a=939.6(2), c=1779(1) pm), Gd{sub 11}Ru{sub 6}Mg{sub 16} (a=951.9(2), c=1756.8(8) pm), and Tb{sub 10.5}Ru{sub 6}Mg{sub 16.5} (a=942.5(1), c=1758.3(4) pm) crystallize with the tetragonal Nd{sub 9.34}Ru{sub 6}Mg{sub 17.66} type structure, space group I4/mmm. This structure exhibits a complex condensation pattern of square-prisms and square-antiprisms around the magnesium and ruthenium atoms, respectively. Y{sub 2}RuMg{sub 2} (a=344.0(1), c=2019(1) pm) and Tb{sub 2}RuMg{sub 2} (a=341.43(6), c=2054.2(7) pm) adopt the Er{sub 2}RuMg{sub 2} structure and Tm{sub 3}Ru{sub 2}Mg (a=337.72(9), c=1129.8(4) pm) is isotypic with Sc{sub 3}Ru{sub 2}Mg. Tm{sub 3}Ru{sub 2}Mg{sub 2} (a=337.35(9), c=2671(1) pm) and Lu{sub 3}Ru{sub 2}Mg{sub 2} (a=335.83(5), c=2652.2(5) pm) are the first ternary ordered variants of the Ti{sub 3}Cu{sub 4} type, space group I4/mmm. These five compounds belong to a large family of intermetallics which are completely ordered superstructures of the bcc subcell. The group-subgroup scheme for Lu{sub 3}Ru{sub 2}Mg{sub 2} is presented. The common structural motif of all three structure types are ruthenium-centered rare earth cubes reminicent of the CsCl type. Magnetic susceptibility measurements of Y{sub 2}RuMg{sub 2} and Lu{sub 3}Ru{sub 2}Mg{sub 2} samples revealed Pauli paramagnetism of the conduction electrons.

  12. The Rare Earth Magnet Industry and Rare Earth Price in China

    Directory of Open Access Journals (Sweden)

    Ding Kaihong

    2014-07-01

    Full Text Available In the past four years, the price of rare earth metal fluctuates sharply for many reasons. Currently, it has become more stable and more reasonable. This presentation is focused on the effect about the rare earth metal price. Some motor manufacturers have shifted from rare earth permanent magnet to ferrite magnet. Many motor manufacturers changed the design for the motor cooling system to make the motor function at a lower temperature. Thus the consumption of Dy can be markedly reduced. As for manufacturer of NdFeB magnet, we are also trying to optimize our process to reduce to dependence of HREE such as Dy and Tb. HS process have been introduced to solve the problem. With more and more people focusing and engaging on the REE industry, the price of REE will be more transparent without too many fluctuations. China is considering the problems of balancing the environment, energy sources, and labor sources. The application field about NdFeB such as wind turbine generator, HEV/EV, FA /OA is flourishing.

  13. Chromatographic Techniques for Rare Earth Elements Analysis

    Science.gov (United States)

    Chen, Beibei; He, Man; Zhang, Huashan; Jiang, Zucheng; Hu, Bin

    2017-04-01

    The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled. Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.

  14. Lateritic, supergene rare earth element (REE) deposits

    Science.gov (United States)

    Cocker, Mark D.

    2014-01-01

    Intensive lateritic weathering of bedrock under tropical or sub-tropical climatic conditions can form a variety of secondary, supergene-type deposits. These secondary deposits may range in composition from aluminous bauxites to iron and niobium, and include rare earth elements (REE). Over 250 lateritic deposits of REE are currently known and many have been important sources of REE. In southeastern China, lateritic REE deposits, known as ion-adsorption type deposits, have been the world’s largest source of heavy REE (HREE). The lateritized upper parts of carbonatite intrusions are being investigated for REE in South America, Africa, Asia and Australia, with the Mt. Weld deposit in Australia being brought into production in late 2012. Lateritic REE deposits may be derived from a wide range of primary host rocks, but all have similar laterite and enrichment profiles, and are probably formed under similar climatic conditions. The weathering profile commonly consists of a depleted zone, an enriched zone, and a partially weathered zone which overlie the protolith. Lateritic weathering may commonly extend to depths of 30 to 60 m. REE are mobilized from the breakdown of primary REE-bearing minerals and redeposited in the enriched zone deeper in the weathering horizon as secondary minerals, as colloids, or adsorbed on other secondary minerals. Enrichment of REE may range from 3 to 10 times that of the source lithology; in some instances, enrichment may range up to 100 times.

  15. Accumulation of rare earth elements by siderophore-forming Arthrobacter luteolus isolated from rare earth environment of Chavara, India.

    Science.gov (United States)

    Emmanuel, E S Challaraj; Ananthi, T; Anandkumar, B; Maruthamuthu, S

    2012-03-01

    In this study, Arthrobacter luteolus, isolated from rare earth environment of Chavara (Quilon district, Kerala, India), were found to produce catechol-type siderophores. The bacterial strain accumulated rare earth elements such as samarium and scandium. The siderophores may play a role in the accumulation of rare earth elements. Catecholate siderophore and low-molecular-weight organic acids were found to be present in experiments with Arthrobacter luteolus. The influence of siderophore on the accumulation of rare earth elements by bacteria has been extensively discussed.

  16. Compact High Current Rare-Earth Emitter Hollow Cathode for Hall Effect Thrusters

    Science.gov (United States)

    Hofer, Richard R. (Inventor); Goebel, Dan M. (Inventor); Watkins, Ronnie M. (Inventor)

    2012-01-01

    An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

  17. Rare earth silicide nanowires on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina

    2008-11-10

    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti {gamma} point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi{sub 2}-monolayer and the Dy{sub 3}Si{sub 5}-multilayer on the Si(111) surface are investigated in comparison to the known ErSi{sub 2}/Si(111) and Er{sub 3}Si{sub 5}/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the (vector)k {sub parallel} space is elliptical at the anti M points, while the hole pocket at the anti {gamma} point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas

  18. Magnetic form factors of rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Deckman, H.W.

    1977-02-01

    The magnetic scattering of neutrons by atoms has been investigated by exploiting its similarity to the radiation problem in spectroscopy. Expressions for the magnetic scattering amplitude have been developed for cases in which an atom in the l/sup n/ electronic configuration is described by a Hamiltonian. For each case, the magnetic scattering amplitude can be expressed in terms of matrix elements of magnetic and electric multipole operators. For a nonrelativistic atom, the calculation of these matrix elements has been separated into evaluating radial matrix elements and matrix elements of Racah tensors W/sup (0,k)k/ and W/sup (1,k')k/. For a relativistic atom the effective operator approach has been used to define effective multipole operators so that a relativistic result is obtained by taking matrix elements of these effective operators between nonrelativistic states of the atom. The calculation of matrix elements of these effective operators has been reduced to evaluating relativistic radial integrals and matrix elements of the Racah tensors taken between nonrelativistic states of the atom. It is shown that for the case of elastic scattering by either a relativistic or nonrelativistic atom in single Russell-Saunders state, the magnetic scattering amplitude can be written in the conventional form p(vector q)vector q/sub m/ . vector sigma. General expressions for p(vector q) as well as elastic magnetic form factors have been obtained. The formalism has been illustrated throughout by applying it to the case of scattering by rare earth ions. Detailed calculations for the form factors of Er and Gd ions are presented.

  19. MBE growth and characterisation of light rare-earth superlattices

    DEFF Research Database (Denmark)

    Ward, R.C.C.; Wells, M.R.; Bryn-Jacobsen, C.

    1996-01-01

    The molecular beam epitaxy growth techniques which have already successfully produced a range of heavy rare-earth superlattices have now been extended to produce superlattices of two light rare-earth elements, Nd/Pr, as well as superlattices and alloy films of a heavy/light system, Ho/Pr. High...

  20. Replacing critical rare earth materials in high energy density magnets

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

    High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

  1. Bragg-grating-based rare-earth-ion-doped channel waveguide lasers and their applications

    NARCIS (Netherlands)

    Bernhardi, Edward

    2012-01-01

    The research presented in this thesis concerns the investigation and development of Bragggrating-based integrated cavities for the rare-earth-ion-doped Al2O3 (aluminium oxide) waveguide platform, both from a theoretical and an experimental point of view, with the primary purpose of realizing

  2. Tracing sediment movement on semi-arid watershed using Rare Earth Elements 1988

    Science.gov (United States)

    A multi-tracer method employing rare earth elements (REE) was used to determine sediment yield and to track sediment movement in a small semiarid watershed. A 0.33 ha watershed near Tombstone, AZ was divided into five morphological units, each tagged with one of five REE oxides. Relative contributi...

  3. PROCESS FOR SEPARATING AMERICIUM AND CURIUM FROM RARE EARTH ELEMENTS

    Science.gov (United States)

    Baybarz, R.D.; Lloyd, M.H.

    1963-02-26

    This invention relates to methods of separating americium and curium values from rare earth values. In accordance with the invention americium, curium, and rare earth values are sorbed on an anion exchange resin. A major portion of the rare earth values are selectively stripped from the resin with a concentrated aqueous solution of lithium chloride, and americium, curium, and a minor portion of rare earth values are then stripped from the resin with a dilute aqueous solution of lithium chloride. The americium and curium values are further purified by increasing the concentration of lithium chloride in the solution to at least 8 molar and selectively extracting rare earth values from the resulting solution with a monoalkylphosphoric acid. (AEC)

  4. Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent.

    Science.gov (United States)

    Kifle, Dejene; Wibetoe, Grethe

    2013-09-13

    One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658nm after post column derivatization with Arsenazo III. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Sensing using rare-earth-doped upconversion nanoparticles.

    Science.gov (United States)

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit.

  6. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    Science.gov (United States)

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

  7. Separation of the rare-earth fission product poisons from spent nuclear fuel

    Science.gov (United States)

    Christian, Jerry D.; Sterbentz, James W.

    2016-08-30

    A method for the separation of the rare-earth fission product poisons comprising providing a spent nuclear fuel. The spent nuclear fuel comprises UO.sub.2 and rare-earth oxides, preferably Sm, Gd, Nd, Eu oxides, with other elements depending on the fuel composition. Preferably, the provided nuclear fuel is a powder, preferably formed by crushing the nuclear fuel or using one or more oxidation-reduction cycles. A compound comprising Th or Zr, preferably metal, is provided. The provided nuclear fuel is mixed with the Th or Zr, thereby creating a mixture. The mixture is then heated to a temperature sufficient to reduce the UO.sub.2 in the nuclear fuel, preferably to at least to 850.degree. C. for Th and up to 600.degree. C. for Zr. Rare-earth metals are then extracted to form the heated mixture thereby producing a treated nuclear fuel. The treated nuclear fuel comprises the provided nuclear fuel having a significant reduction in rare-earths.

  8. Rare earth element deposits in China

    Science.gov (United States)

    Xie, Yu-Ling; Hou, Zeng-qian; Goldfarb, Richard J.; Guo, Xiang; Wang, Lei

    2016-01-01

    China is the world’s leading rare earth element (REE) producer and hosts a variety of deposit types. Carbonatite- related REE deposits, the most significant deposit type, include two giant deposits presently being mined in China, Bayan Obo and Maoniuping, the first and third largest deposits of this type in the world, respectively. The carbonatite-related deposits host the majority of China’s REE resource and are the primary supplier of the world’s light REE. The REE-bearing clay deposits, or ion adsorption-type deposits, are second in importance and are the main source in China for heavy REE resources. Other REE resources include those within monazite or xenotime placers, beach placers, alkaline granites, pegmatites, and hydrothermal veins, as well as some additional deposit types in which REE are recovered as by-products. Carbonatite-related REE deposits in China occur along craton margins, both in rifts (e.g., Bayan Obo) and in reactivated transpressional margins (e.g., Maoniuping). They comprise those along the northern, eastern, and southern margins of the North China block, and along the western margin of the Yangtze block. Major structural features along the craton margins provide first-order controls for REE-related Proterozoic to Cenozoic carbonatite alkaline complexes; these are emplaced in continental margin rifts or strike-slip faults. The ion adsorption-type REE deposits, mainly situated in the South China block, are genetically linked to the weathering of granite and, less commonly, volcanic rocks and lamprophyres. Indosinian (early Mesozoic) and Yanshanian (late Mesozoic) granites are the most important parent rocks for these REE deposits, although Caledonian (early Paleozoic) granites are also of local importance. The primary REE enrichment is hosted in various mineral phases in the igneous rocks and, during the weathering process, the REE are released and adsorbed by clay minerals in the weathering profile. Currently, these REE-rich clays are

  9. [Content of rare earth elements in wild Hypericum japonicum Thunb].

    Science.gov (United States)

    Wei, Zhen-Lin; Rui, Yu-Kui; Tian, Zhi-Huan

    2009-06-01

    Rare earth elements are important nutritional elements for human health, and today more and more attention has been paid to the effective components in Chinese traditional medicine, especially to rare earth elements. Fifteen rare earth elements in wild hypericum japonicum Thunb were analyzed by the methods of ICP-MS. The results showed that the concentrations of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Tm, Lu and Y ranged from 6 ng x g(-1) x DW to 14 522 ng x g(-1) x DW, and among them the concentrations of La, Ce and Nd were higher than 2 000 ng x g(-1) x DW. Compared with the concentration of rare earth elements in rice, corn, wheat and barley, the total concentration of rare earth elements in hypericum japonicum Thunb was much higher, which could be the mechanism of curative effect of hypericum japonicum Thunb on liverish diseases. The character of elements and the content of rare earth elements in soil should be responsible for the difference, but the distributive mechanism of rare earth elements in hypericum japonicum Thunb should be further studied.

  10. Bioleaching of rare earth elements from monazite sand.

    Science.gov (United States)

    Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

    2016-02-01

    Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

  11. Rare earth element enrichment using membrane based solvent extraction

    Science.gov (United States)

    Makertiharta, I. G. B. N.; Dharmawijaya, P. T.; Zunita, M.; Wenten, I. G.

    2017-01-01

    The chemical, catalytic, electrical, magnetic, and optical properties of rare earth elements are required in broad applications. Rare earth elements have similar physical and chemical properties thus it is difficult to separate one from each other. Rare earth element is relatively abundant in earth's crust but rarely occur in high concentrated deposits. Traditionally, ion-exchange and solvent extraction techniques have been developed to separate and purify single rare earth solutions or compounds. Recently, membrane starts to gain attention for rare earth separation by combining membrane and proven technologies such as solvent extraction. Membrane-based process offers selective, reliable, energy efficient and easy to scale up separation. During membrane-based separation process, one phase passes through membrane pores while the other phase is rejected. There is no direct mixing of two phases thus the solvent loss is very low. Membrane can also lower solvent physical properties requirement (viscosity, density) and backmixing, eliminate flooding phenomenon and provide large interfacial area for mass transfer. This paper will summarize research efforts in developing membrane technology for rare earth element separation. Special attention will be given to solvent extraction related process as the commonly used method for rare earth element separation. Furthermore, membrane configuration and its potentials will also be discussed.

  12. Crystallization behavior of rare-earth doped fluorochlorozirconate glasses.

    Science.gov (United States)

    Paßlick, C; Ahrens, B; Henke, B; Johnson, J A; Schweizer, S

    2011-06-01

    A series of fluorochlorozirconate (FCZ) glasses, each doped with a different rare-earth, was prepared and examined to determine thermal stability and activation energy, Ea , of the dopant dependent BaCl2 crystallization. Non-isothermal differential scanning calorimetry (DSC) measurements were done to investigate the endothermic and exothermic reactions upon heat treatment of the glass samples. In comparison to the rare-earth free FCZ glass, significant changes in the Hruby constant, Hr , and Ea were found due to the addition of a rare-earth and also between the individual dopants.

  13. Electrochemical performance of the rare-earth perovskite-type oxide La0.6Sr0.4Co0.2Fe0.8O3 as negative electrode material for Ni/oxide rechargeable batteries

    Directory of Open Access Journals (Sweden)

    John Henao

    2017-08-01

    Full Text Available Abstract In this paper, the perovskite-type oxide La0.6Sr0.4Co0.2Fe0.8O3 was evaluated as a novel negative electrode material for Ni/oxide rechargeable batteries. The structure and morphology of the as-prepared powder was studied by scanning electron microscopy and X-ray diffraction. The electrochemical performance of the perovskite-type oxide was investigated using chronopotentiometric, chronoamperometric and potentiodynamic polarization techniques. The maximum discharge capacity values of the perovskite-type electrodes were obtained during the first three cycles (51, 172 and 462 mAh g−1 at 298, 313 and 333 K, respectively. The maximum adsorption capability of hydrogen in the perovskite-type electrode was 1.72% wt. hydrogen at a current rate of 125 mA g−1, 333 K and 6 M KOH. The cycling ability was fairly good with 64% capacity conservation after 20 cycles at 333 K. The electrochemical evaluation was also performed using different electrolyte concentrations; interestingly, the maximum discharge capacity of the perovskite-type electrodes increased in a linear-like manner with the incremental changes in electrolyte concentration. The hydrogen diffusion coefficient and exchange current density were also estimated to discuss the kinetics of the process.

  14. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  15. Life cycle inventory of the production of rare earths and the subsequent production of NdFeB rare earth permanent magnets.

    Science.gov (United States)

    Sprecher, Benjamin; Xiao, Yanping; Walton, Allan; Speight, John; Harris, Rex; Kleijn, Rene; Visser, Geert; Kramer, Gert Jan

    2014-04-01

    Neodymium is one of the more critical rare earth elements with respect to current availability and is most often used in high performance magnets. In this paper, we compare the virgin production route of these magnets with two hypothetical recycling processes in terms of environmental impact. The first recycling process looks at manual dismantling of computer hard disk drives (HDDs) combined with a novel hydrogen based recycling process. The second process assumes HDDs are shredded. Our life cycle assessment is based both on up to date literature and on our own experimental data. Because the production process of neodymium oxide is generic to all rare earths, we also report the life cycle inventory data for the production of rare earth oxides separately. We conclude that recycling of neodymium, especially via manual dismantling, is preferable to primary production, with some environmental indicators showing an order of magnitude improvement. The choice of recycling technology is also important with respect to resource recovery. While manual disassembly allows in principle for all magnetic material to be recovered, shredding leads to very low recovery rates (<10%).

  16. Rare earth elements exploitation, geopolitical implications and raw materials trading

    Science.gov (United States)

    Chemin, Marie-Charlotte

    2015-04-01

    Rare earth elements (REE) correspond to seventeen elements of the periodic table. They are used in high technology, cracking, electric cars' magnet, metal alloy for batteries, and also in phone construction or ceramics for electronic card. REEs are an important resource for high technology. This project targets 16 years old students in the subject "personalized aid" and will last six weeks. The purpose of this project is to develop autonomy and research in groups for a transdisciplinary work. This project gathers knowledge in geology, geography and economics. During the first session students analyze the geology applications of the REE. They begin the analysis with learning the composition in different rocks such as basalt and diorite to make the link with crystallization. Then they compare it with adakite to understand the formation of these rocks. In the second session, they study REE exploitation. We can find them as oxides in many deposits. The principal concentrations of rare earth elements are associated with uncommon varieties of igneous rocks, such as carbonatites. They can use Qgis, to localize this high concentration. In the third session, they study the environmental costs of REE exploitation. Indeed, the exploitation produces thorium and carcinogenic toxins: sulphates, ammonia and hydrochloric acid. Processing one ton of rare earths produces 2,000 tons of toxic waste. This session focuses, first, on Baotou's region, and then on an example they are free to choose. In the fourth session, they study the geopolitical issues of REE with a focus on China. In fact this country is the largest producer of REE, and is providing 95% of the overall production. REE in China are at the center of a geopolitical strategy. In fact, China implements a sort of protectionism. Indeed, the export tax on REE is very high so, as a foreign company, it is financially attractive to establish a manufacturing subsidiary in China in order to use REE. As a matter of fact

  17. A reactive distillation process for the treatment of LiCl-KCl eutectic waste salt containing rare earth chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Eun, H.C., E-mail: ehc2004@kaeri.re.kr; Choi, J.H.; Kim, N.Y.; Lee, T.K.; Han, S.Y.; Lee, K.R.; Park, H.S.; Ahn, D.H.

    2016-11-15

    The pyrochemical process, which recovers useful resources (U/TRU metals) from used nuclear fuel using an electrochemical method, generates LiCl-KCl eutectic waste salt containing radioactive rare earth chlorides (RECl{sub 3}). It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste salt in a hot-cell facility. For this reason, a reactive distillation process using a chemical agent was achieved as a method to separate rare earths from the LiCl-KCl waste salt. Before conducting the reactive distillation, thermodynamic equilibrium behaviors of the reactions between rare earth (Nd, La, Ce, Pr) chlorides and the chemical agent (K{sub 2}CO{sub 3}) were predicted using software. The addition of the chemical agent was determined to separate the rare earth chlorides into an oxide form using these equilibrium results. In the reactive distillation test, the rare earth chlorides in LiCl-KCl eutectic salt were decontaminated at a decontamination factor (DF) of more than 5000, and were mainly converted into oxide (Nd{sub 2}O{sub 3}, CeO{sub 2}, La{sub 2}O{sub 3}, Pr{sub 2}O{sub 3}) or oxychloride (LaOCl, PrOCl) forms. The LiCl-KCl was purified into a form with a very low concentration (<1 ppm) for the rare earth chlorides.

  18. Local magnetic susceptibility in rare-earth compounds

    CERN Document Server

    Shiozawa, H; Obu, K

    2003-01-01

    The element specific magnetic susceptibilities of some rare-earth compounds are estimated by measuring magnetic circular dichroism at rare-earth M sub 4 sub , sub 5 absorption edges. The temperature dependences of the rare-earth 4f local magnetic susceptibilities in dense Kondo materials, CeNi, CeSn sub 3 and CeRu sub 4 Sb sub 1 sub 2 , are remarkably different from those of the bulk magnetic susceptibilities measured by a conventional magnetometer, although the 4f electron is regarded to mainly hold the magnetic moment in these compounds. In contrast, the rare-earth 4f local magnetic susceptibility of ferromagnetic NdFe sub 4 P sub 1 sub 2 shows almost as similar behavior as the bulk one.

  19. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...

  20. Rare earths: Market disruption, innovation, and global supply chains

    Science.gov (United States)

    Eggert, Roderick; Wadia, Cyrus; Anderson, Corby; Bauer, Diana; Fields, Fletcher; Meinert, Lawrence D.; Taylor, Patrick

    2016-01-01

    Rare earths, sometimes called the vitamins of modern materials, captured public attention when their prices increased more than ten-fold in 2010 and 2011. As prices fell between 2011 and 2016, rare earths receded from public view—but less visibly they became a major focus of innovative activity in companies, government laboratories and universities. Geoscientists worked to better understand the resource base and improve our knowledge about mineral deposits that will be mines in the future. Process engineers carried out research that is making primary production and recycling more efficient. Materials scientists and engineers searched for substitutes that will require fewer or no rare earths while providing properties comparable or superior to those of existing materials. As a result, even though global supply chains are not significantly different now than they were before the market disruption, the innovative activity motivated by the disruption likely will have far-reaching, if unpredictable, consequences for supply chains of rare earths in the future.

  1. Radioluminescence study of rare earth doped some yttrium based phosphors

    Science.gov (United States)

    Ayvacıklı, Mehmet; Ege, Arzu; Ekdal, Elçin; Popovici, Elisabeth-Jeanne; Can, Nurdoğan

    2012-09-01

    This paper reports the luminescence emission spectra of Y(Ta,Nb)O4 activated by rare earth ions such as Eu3+ and Tb3+. The influence of these rare earth ions on the radioluminescence (RL) of yttrium niobate and tantalate phosphors was investigated. The luminescent properties were studied under X-ray and preliminary RL measurements to further evaluate prepared materials. The emission centers of the rare earth activators (Eu3+, Tb3+) were found to contribute efficiently to the total luminescence. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing the broad band variation of visible RL from blue to red.

  2. Monolithic Rare Earth Doped PTR Glass Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of the project is to demonstrate the feasibility of a monolithic solid state laser on the basis of PTR glass co-doped with luminescent rare earth ions....

  3. Preparation of Pt Ru/C + rare earths by the method of reduction by alcohol for the electro-oxidation of ethanol; Preparacao de eletrocatalisadores PtRu/C + terras raras pelo metodo da reducao por alcool para a eletro-oxidacao do etanol

    Energy Technology Data Exchange (ETDEWEB)

    Tusi, M.M.; Rodrigues, R.M.S.; Spinace, E.V.; Oliveira Neto, A., E-mail: aolivei@ipen.b, E-mail: espinace@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2010-07-01

    PtRu/C electrocatalyst was prepared in a single step, while that PtRu/85%C-15%Ce, PtRu/85%C-15%La, PtRu/85%C-15%Nd and PtRu/85%C-15%Er electrocatalyst were prepared in a two step. In the first step a Carbon Vulcan XC72 + rare earth supports were prepared. In the second step PtRu electrocatalyst were prepared by an alcohol-reduction process using ethylene glycol as solvent and reducing agent and supported on Vulcan XC72 + earth rare. The obtained electrocatalysts were characterized by EDAX, XRD and chronoamperometry. The electro-oxidation of ethanol was studied by chronoamperometry at room temperature. PtRu/85%C- 15%Ce electrocatalyst showed a significant increase of performance for ethanol oxidation compared to PtRu/C electrocatalyst. (author)

  4. Electroluminescent devices based on rare-earth tetrakis {beta}-diketonate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, W.G.; Legnani, C. [CeDO-Centro de Dispositivos Organicos, Dimat-Inmetro, 25250-020, Duque de Caxias, Rio de Janeiro, RJ (Brazil); Santos, R.M.B. dos [LOEM-Laboratorio de Optoeletronica Molecular, Physics Department, PUC-Rio, 22452-970, Rio de Janeiro, RJ (Brazil); Teixeira, K.C. [CeDO-Centro de Dispositivos Organicos, Dimat-Inmetro, 25250-020, Duque de Caxias, Rio de Janeiro, RJ (Brazil); LOEM-Laboratorio de Optoeletronica Molecular, Physics Department, PUC-Rio, 22452-970, Rio de Janeiro, RJ (Brazil); Cremona, M. [CeDO-Centro de Dispositivos Organicos, Dimat-Inmetro, 25250-020, Duque de Caxias, Rio de Janeiro, RJ (Brazil); LOEM-Laboratorio de Optoeletronica Molecular, Physics Department, PUC-Rio, 22452-970, Rio de Janeiro, RJ (Brazil)], E-mail: cremona@fis.puc-rio.br; Guedes, M.A. [CeDO-Centro de Dispositivos Organicos, Dimat-Inmetro, 25250-020, Duque de Caxias, Rio de Janeiro, RJ (Brazil); Brito, H.F. [Instituto de Quimica, Departamento de Quimica Fundamental, USP, 05599-970, Sao Paulo, SP (Brazil)

    2008-12-01

    In this paper the synthesis, photoluminescence and electroluminescence investigation of the novel tetrakis {beta}-diketonate of rare-earth complexes such as, M[Eu(dbm){sub 4}] and M[Tb(acac){sub 4}] with a variety of cationic ligands, M = Li{sup +}, Na{sup +} and K{sup +} have been investigated. The emission spectra of the Eu{sup 3+} and Tb{sup 3+} complexes displayed characteristic narrow bands arising from intraconfigurational transitions of trivalent rare-earth ions and exhibited red color emission for the Eu{sup 3+} ion ({sup 5}D{sub 0}{yields}{sup 7}F{sub J}, J = 0-6) and green for the Tb{sup 3+} ion ({sup 5}D{sub 4}{yields}{sup 7}F{sub J}, J = 6-0). The lack of the broaden emission bands arising from the ligands suggests the efficient intramolecular energy transfer from the dbm and acac ligands to Eu{sup 3+} and Tb{sup 3+} ions, respectively. In accordance to the expected, the values of PL quantum efficiency ({eta}) of the emitting {sup 5}D{sub 0} state of the tetrakis({beta}-diketonate) complexes of Eu{sup 3+} were higher compared with those tris-complexes. Therefore, organic electroluminescent (EL) devices were fabricated with the structure as follows: indium tin oxide (ITO)/hole transport layer (HTL) NPB or MTCD/emitter layer M[RE({beta}-diketonate){sub 4}] complexes)/Aluminum (Al). All the films were deposited by thermal evaporation carried out in a high vacuum environment system. The OLED light emission was independent of driving voltage, indicating that the combination of charge carriers generates excitons within the M[RE({beta}-diketonate){sub 4}] layers, and the energy is efficiently transferred to RE{sup 3+} ion. As a best result, a pure red and green electroluminescent emission was observed from the Eu{sup 3+} and Tb{sup 3+} devices, confirmed by (X,Y) color coordinates.

  5. Rare Earth-Activated Silica-Based Nanocomposites

    Directory of Open Access Journals (Sweden)

    C. Armellini

    2007-01-01

    Full Text Available Two different kinds of rare earth-activated glass-based nanocomposite photonic materials, which allow to tailor the spectroscopic properties of rare-earth ions: (i Er3+-activated SiO2-HfO2 waveguide glass ceramic, and (ii core-shell-like structures of Er3+-activated silica spheres obtained by a seed growth method, are presented.

  6. Negative Refraction in Rare-Earth Doped Crystals

    Science.gov (United States)

    2016-06-09

    AFRL-AFOSR-VA-TR-2016-0221 NEGATIVE REFRACTION IN RARE-EARTH DOPED CRYSTALS Deniz Yavuz UNIVERSITY OF WISCONSIN SYSTEM MADISON WI Final Report 06/09...DATES COVERED (From - To) March 2013-February 2016 4. TITLE AND SUBTITLE NEGATIVE REFRACTION IN RARE-EARTH DOPED CRYSTALS 5a. CONTRACT NUMBER...ABSTRACT In this project, our long-term goal is to demonstrate the first negative refraction in atomic systems. Although the concept of negative

  7. Theoretical prediction of topological insulator in ternary rare earth chalcogenides

    OpenAIRE

    Yan, Binghai; Zhang, Hai-Jun; Liu, Chao-Xing; Qi, Xiao-Liang; Frauenheim, Thomas; Zhang, Shou-Cheng

    2010-01-01

    A new class of three-dimensional topological insulator, ternary rare earth chalcogenides, is theoretically investigated with ab initio calculations. Based on both bulk band structure analysis and the direct calculation of topological surface states, we demonstrate that LaBiTe3 is a topological insulator. La can be substituted by other rare earth elements, which provide candidates for novel topological states such as quantum anomalous Hall insulator, axionic insulator and topological Kondo ins...

  8. Electrical and carrier transport properties of the Au/Y2O3/n-GaN metal-insulator-semiconductor (MIS) diode with rare-earth oxide interlayer

    Science.gov (United States)

    Venkata Prasad, C.; Rajagopal Reddy, V.; Choi, Chel-Jong

    2017-04-01

    The electrical and transport properties of rare-earth Y2O3 on n-type GaN with Au electrode have been investigated by current-voltage and capacitance-voltage techniques at room temperature. The Au/Y2O3/n-GaN metal-insulator-semiconductor (MIS) diode shows a good rectification behavior compared to the Au/n-GaN metal-semiconductor (MS) diode. Statistical analysis showed that a mean barrier height (BH) and ideality factor are 0.78 eV and 1.93, and 0.96 eV and 2.09 for the Au/n-GaN MS and Au/Y2O3/n-GaN MIS diodes, respectively. Results indicate that the high BH is obtained for the MIS diode compared to the MS diode. The BH, ideality factor and series resistance are also estimated by Cheung's function and Norde method. From the forward current-voltage data, the interface state density ( N SS) is estimated for both the MS and MIS Schottky diodes, and found that the estimated N SS is lower for the MIS diode compared to the MS diode. The results reveal that the introduction of Y2O3 interlayer facilitated the reduction of N SS of the Au/n-GaN interface. Experimental results suggest that the Poole-Frenkel emission is a dominant conduction mechanism in the reverse bias region of both Au/n-GaN MS and Au/Y2O3/n-GaN MIS diodes.

  9. Ferroelectricity of domain walls in rare earth iron garnet films.

    Science.gov (United States)

    Popov, A I; Zvezdin, K A; Gareeva, Z V; Mazhitova, F A; Vakhitov, R M; Yumaguzin, A R; Zvezdin, A K

    2016-11-16

    In this paper, we report on electric polarization arising in a vicinity of Bloch-like domain walls in rare-earth iron garnet films. The domain walls generate an intrinsic magnetic field that breaks an antiferroelectric structure formed in the garnets due to an exchange interaction between rare earth and iron sublattices. We explore 180° domain walls whose formation is energetically preferable in the films with perpendicular magnetic anisotropy. Magnetic and electric structures of the 180° quasi-Bloch domain walls have been simulated at various relations between system parameters. Singlet, doublet ground states of rare earth ions and strongly anisotropic rare earth Ising ions have been considered. Our results show that electric polarization appears in rare earth garnet films at Bloch domain walls, and the maximum of magnetic inhomogeneity is not always linked to the maximum of electric polarization. A number of factors including the temperature, the state of the rare earth ion and the type of a wall influence magnetically induced electric polarization. We show that the value of polarization can be enhanced by the shrinking of the Bloch domain wall width, decreasing the temperature, and increasing the deviations of magnetization from the Bloch rotation that are regulated by impacts given by magnetic anisotropies of the films.

  10. Characterization of rare-earth doped Si 3 N4 /SiC micro/nanocomposites

    Directory of Open Access Journals (Sweden)

    Peter Tatarko

    2010-03-01

    Full Text Available Influence of various rare-earth oxide additives (La2O3, Nd2O3, Sm2O3, Y2O3, Yb2O3 and Lu2O3 on the mechanical properties of hot-pressed silicon nitride and silicon nitride/silicon carbide micro/nano-composites has been investigated. The bimodal character of microstructures was observed in all studied materials where elongated β-Si3N4 grains were embedded in the matrix of much finer Si3N4 grains. The fracture toughness values increased with decreasing ionic radius of rare-earth elements. The fracture toughness of composites was always lower than that of monoliths due to their finer Si3N4/SiC microstructures. Similarly, the hardness and bending strength values increased with decreasing ionic radius of rare-earth elements either in monoliths or composites. On the other hand, the positive influence of finer microstructure of the composites on strength was not observed due to the present defects in the form of SiC clusters and non-reacted carbon zones. Wear resistance at room temperature also increased with decreasing ionic radius of rare-earth element. Significantly improved creep resistance was observed in case either of composite materials or materials with smaller radius of RE3+.

  11. Photo-Induced conductivity of heterojunction GaAs/Rare-Earth doped SnO2

    Directory of Open Access Journals (Sweden)

    Cristina de Freitas Bueno

    2013-01-01

    Full Text Available Rare-earth doped (Eu3+ or Ce3+ thin layers of tin dioxide (SnO2 are deposited by the sol-gel-dip-coating technique, along with gallium arsenide (GaAs films, deposited by the resistive evaporation technique. The as-built heterojunction has potential application in optoelectronic devices, because it may combine the emission from the rare-earth-doped transparent oxide, with a high mobility semiconductor. Trivalent rare-earth-doped SnO2 presents very efficient emission in a wide wavelength range, including red (in the case of Eu3+ or blue (Ce3+. The advantage of this structure is the possibility of separation of the rare-earth emission centers, from the electron scattering, leading to an indicated combination for electroluminescence. Electrical characterization of the heterojunction SnO2:Eu/GaAs shows a significant conductivity increase when compared to the conductivity of the individual films. Monochromatic light excitation shows up the role of the most external layer, which may act as a shield (top GaAs, or an ultraviolet light absorber sink (top RE-doped SnO2. The observed improvement on the electrical transport properties is probably related to the formation of short conduction channels in the semiconductors junction with two-dimensional electron gas (2DEG behavior, which are evaluated by excitation with distinct monochromatic light sources, where the samples are deposited by varying the order of layer deposition.

  12. MICROBIALLY MEDIATED LEACHING OF RARE EARTH ELEMENTS FROM RECYCLABLE MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Reed, D. W.; Fujita, Y.; Daubaras, D. L.; Bruhn, D. F.; Reiss, J. H.; Thompson, V. S.; Jiao, Y.

    2016-09-01

    Bioleaching offers a potential approach for recovery of rare earth elements (REE) from recyclable materials, such as fluorescent lamp phosphors or degraded industrial catalysts. Microorganisms were enriched from REE-containing ores and recyclable materials with the goal of identifying strains capable of extracting REE from solid materials. Over 100 heterotrophic microorganisms were isolated and screened for their ability to produce organic acids capable of leaching REE. The ten most promising isolates were most closely related to Pseudomonas, Acinetobacter and Talaromyces. Of the acids produced, gluconic acid appeared to be the most effective at leaching REE (yttrium, lanthanum, cerium, europium, and terbium) from retorted phosphor powders (RPP), fluidized cracking catalyst (FCC), and europium-doped yttrium oxide (YOEu). We found that an Acinetobacter isolates, BH1, was the most capable strain and able to leach 33% of the total REE content from the FCC material. These results support the continuing evaluation of gluconic acid-producing microbes for large-scale REE recovery from recyclable materials.

  13. The chemistry of rare earth elements in the solar nebula

    Science.gov (United States)

    Larimer, J. W.; Bartholomay, H. A.; Fegley, B.

    1984-01-01

    The high concentration of rare earth elements (REE) in primitive CaS suggests that the REE along with the other normally lithophile elements form stable sulfides under the unusual conditions which existed during the formation of enstatite chrondites. In order to acquire a more quantitative framework in which to interpret these data, the behavior of the REE in systems with solar, or slightly fractionated solar, composition is being studied. These new data introduce modest changes in the behavior of some of the REE when compared to previous studies. For example, the largest differences are in the stabilities of the gaseous monoxides of Ce, Eu, Tb, Ho, and Tm, all of which now appear to be less stable than previously thought, and YbO(g) which is somewhat more stable. Much more significant are the changes in REE distribution in the gas phase in fractionated systems, especially those made more reducing by changing the C/O ratio from the solar value of 0.6 to about 1.0. In almost all cases, the exceptions being Eu, Tm and Yb whose elemental gaseous species dominate, the monosulfides become more abundant. Moreover, the solid oxides of Eu, Tm and Yb become less stable under more reducing conditions which, in effect, should reduce the condensation temperature of all REE in more reduced systems.

  14. Advanced Characterization of Rare Earth Elements in Coal Utilization Byproducts

    Science.gov (United States)

    Verba, C.; Scott, M.; Dieterich, M.; Poston, J.; Collins, K.

    2016-12-01

    Rare earth elements (REE) in various forms (e.g., crystalline mineral phases; adsorbed/absorbed state on and into organic macerals, neoformed glass from flyash or bottom ash) from domestic feedstocks such as coal deposits to coal utilization byproducts (CUB) have the potential to reduce foreign REE dependence and increase domestic resource security. Characterization is critical for understanding environmental risks related to their fate and transport as well as determining the most practical and economical techniques for concentrating the REE and converting them into chemical stocks for manufacturing. Several complementary electron microscopy (SEM-EDS, EPMA-WDS, FIB-SEM, cathodoluminescence, and XRD) and post image processing techniques were used to understand REE transition from coal to CUB. Sites of interest were identified and imaged and respective elemental x-ray maps acquired and montaged. Pixel classification of SEM imagers was completed using image analysis techniques to quantify the distribution of REE associated features. Quantitative elemental analysis of phases were completed using EMPA-WDS followed by FIB-SEM. The FIB-SEM results were reconstructed into 3D volumes and features of interest (e.g. monazite) were analyzed to determine the structure and volumetric estimation of REEs and thus predict detrital REE phases to ICP-MS results. Trace minerals were identified as pyrite, zircon, REE-phosphates' (monazite, xenotime), and barite within the coal tailings. In CUB, amorphous aluminosilicates, iron oxide cenospheres, and calcium oxides were present; monazite appear to be unaltered and unaffected by the combustion process in these samples. Thermal decomposition may have occurred due to presence of detrital zircon and xenotime and subsequent thin Ca-oxide coating enriched in trace REEs.

  15. A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

    Science.gov (United States)

    Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

    2017-09-15

    Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Persistent-current switch for pancake coils of rare earth-barium-copper-oxide high-temperature superconductor: Design and test results of a double-pancake coil operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K)

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Timing; Michael, Philip C.; Bascuñán, Juan; Iwasa, Yukikazu, E-mail: iwasa@jokaku.mit.edu [Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, Massachusetts 02139 (United States); Voccio, John [Wentworth Institute of Technology, 550 Huntington Ave, Boston, Massachusetts 02115 (United States); Hahn, Seungyong [National High Magnetic Field Laboratory, Florida State University, Tallahassee, 2031 Paul Dirac Drive, Florida 32310 (United States)

    2016-08-22

    We present design and test results of a superconducting persistent current switch (PCS) for pancake coils of rare-earth-barium-copper-oxide, REBCO, high-temperature superconductor (HTS). Here, a REBCO double-pancake (DP) coil, 152-mm ID, 168-mm OD, 12-mm high, was wound with a no-insulation technique. We converted a ∼10-cm long section in the outermost layer of each pancake to a PCS. The DP coil was operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K). Over the operating temperature ranges of this experiment, the normal-state PCS enabled the DP coil to be energized; thereupon, the PCS resumed the superconducting state and the DP coil field decayed with a time constant of 100 h, which would have been nearly infinite, i.e., persistent-mode operation, were the joint across the coil terminals superconducting.

  17. BASIC RESEARCH ON THE SEPARATION OF SCANDIUM YTTRIUM, AND THE RARE EARTHS BY SOLVENT EXTRACTION.

    Science.gov (United States)

    RARE EARTH ELEMENTS, * SOLVENT EXTRACTION ), (*CHELATE COMPOUNDS, RARE EARTH ELEMENTS), PURIFICATION, ATOMIC SPECTROSCOPY, SCANDIUM, YTTRIUM, PRASEODYMIUM, SAMARIUM, EUROPIUM, GADOLINIUM, TERBIUM, FLUORINE COMPOUNDS, KETONES

  18. Development of a methodology for the separation of europium and samarium from a mixture of rare earth oxides by electroreduction/ precipitation; Desenvolvimento de uma metodologia para a separacao de samario e europio a partir de mistura de oxidos de terras raras por reducao eletroquimica/precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Chepcanoff, Vera

    2006-07-01

    The rare earths (RE) were first used in 1903, when Welsbach developed a lighter that is still used today. Nowadays, the RE are employed in many different fields, as in the production of super-alloys , as catalysts for petroleum industry, in the manufacture of non-ferrous alloys, color television tubes, x-ray screens, special glasses, ceramics, computer industries, nuclear medicine, lasers, pigments, etc., moving, in the last decade , a market of US$ 2 billions per year. Due to their similar properties, the RE elements are very difficult to separate, requiring complex processes, what make the products very expensive. Elements like Eu and Sm, which contents in the minerals are low (0.05% and 2.0%, respectively, in monazite) are extremely expensive, but their field of application justifies the research for looking for other processes, more simple and/or more effective. Trivalent state is a characteristic of all RE, but some of them presents oxidation state +2, like Ce, Eu, Sm and Yb. In the case of Eu and Sm, the focus of the present work, the divalent state is achieved by electro-reduction in the potentials -0.65 and -1.55 (SCE), respectively. This makes possible the separation of these elements from the other rare earths and from each other. Thus, making use of this characteristic, a process for the individual separation of Eu and Sm in (NH{sub 4}){sub 2}SO{sub 4} solution by electro-reduction/precipitation is proposed, where Sm is first separated from the solution as sulfate, and Eu, that remains in the solution, is precipitated after the decrease of temperature and potential applied. The process developed from a synthetic Eu and Sm solution was applied to a mixture of semi-heavy RE oxide, produced at IPEN-CNEN/SP, obtaining the separation of Sm. This product was analyzed by spectrophotometry, showing high purity. (author)

  19. Ultraviolet absorption and excitation spectroscopy of rare-earth-doped glass fibers derived from glassy and crystalline preforms

    Science.gov (United States)

    Dragic, Peter D.; Liu, Yuh-Shiuan; Galvin, Thomas C.; Eden, J. G.

    2012-02-01

    Ultraviolet absorption and laser excitation spectroscopy (LES) measurements are presented for rare-earth-doped optical fibers produced from both glassy and crystalline preforms. Absorption spectra are obtained via broad-spectrum UV LEDs emitting in the 250nm region. LES measurements are obtained utilizing a tunable UV laser source. The tunable laser employed is a frequency-doubled titanium:sapphire laser-pumped optical parametric amplifier (OPA) operating down to a minimum wavelength of about 225nm. Our results indicate a roughly linear relationship between the concentration of oxygen deficiency centers (ODC) and rare-earth content, regardless of the preform type, and the slope of the line is found to vary significantly with the rare earth. Additionally, LES measurements are used to elucidate the energy transfer mechanism from pumping in the UV to emission by the rare-earth. In all cases the fibers are Al codoped and those produced from glassy preforms are manufactured via standard methods. Fibers produced from crystalline preforms start with a pure silica-sleeved rare-earth doped YAG crystal rod that becomes glassy (amorphous) post-draw.

  20. Online preconcentration ICP-MS analysis of rare earth elements in seawater

    OpenAIRE

    Hathorne, Ed C.; Haley, Brian; Stichel, Torben; Grasse, Patricia; Zieringer, Moritz; Frank, Martin

    2012-01-01

    The rare earth elements (REEs) with their systematically varying properties are powerful tracers of continental inputs, particle scavenging intensity and the oxidation state of seawater. However, their generally low (?pmol/kg) concentrations in seawater and fractionation potential during chemical treatment makes them difficult to measure. Here we report a technique using an automated preconcentration system, which efficiently separates seawater matrix elements and elutes the preconcentrated s...

  1. Preliminary Study of Development of the Organization of Rare-Earth Exportation Countries (OREEC

    Directory of Open Access Journals (Sweden)

    Takashi Kamei

    2013-03-01

    Full Text Available The largest two sectors emitting CO2 in the world are electricity generation and land-transportation. Therefore, nuclear power plays an important role in generating electricity with low CO2 emission. An important aspect needs to be considered to ensure environmental sustainability is nuclear non-proliferation and less amount of radioactive waste generated. Thus the use of "thorium" as nuclear fuel has received increasing interest because thorium produces little amount of plutonium and very little amount of long-lived minor actinide. However, thorium cannot be used immediately due to its lack of fissile isotope indispensable to start fission reaction. At the same time, electric vehicle and hybrid-vehicle become more popular as low-carbon automobiles. Rare-earth elements are indispensable for manufacturing these low-carbon automobiles. However the problem with rare-earth production is its radioactive by-product of "thorium". Since the largest potential of consuming thorium by nuclear power still needs several decades for commercializing, there becomes a discrepancy in consumption and production of thorium causing unused stockpile of thorium. Several countries have announced to supply rare-earth but this cannot be safely and economically done unless thorium problem is solved. In this paper, an international framework called the "OREEC: Organization of Rare-Earth Exportation Countries" is proposed as a solution to this issue. The OREEC has mainly three functions: (1 ThAX, which is a financial collecting method, (2 Th FREE label, which is certification of adequate treatment of thorium and (3 The Bank, which stores separated thorium.

  2. Optical Frequency Comb Spectroscopy of Rare Earth Atoms

    Science.gov (United States)

    Swiatlowski, Jerlyn; Palm, Christopher; Joshi, Trinity; Montcrieffe, Caitlin; Jackson Kimball, Derek

    2013-05-01

    We discuss progress in our experimental program to employ optical-frequency-comb-based spectroscopy to understand the complex spectra of rare-earth atoms. We plan to carry out systematic measurements of atomic transitions in rare-earth atoms to elucidate the energy level structure and term assignment and determine presently unknown atomic state parameters. This spectroscopic information is important in view of the increasing interest in rare-earth atoms for atomic frequency standards, in astrophysical investigations of chemically peculiar stars, and in tests of fundamental physics (tests of parity and time-reversal invariance, searches for time variation of fundamental constants, etc.). We are presently studying the use of hollow cathode lamps as atomic sources for two-photon frequency comb spectroscopy. Supported by the National Science Foundation under grant PHY-0958749.

  3. Thermal shock behavior of rare earth modified alumina ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junlong; Liu, Changxia [Ludong Univ., Yantai (China). School of Transportation

    2017-05-15

    Alumina matrix ceramic composites toughened by AlTiC master alloys, diopside and rare earths were fabricated by hot-pressing and their thermal shock behavior was investigated and compared with that of monolithic alumina. Results showed that the critical thermal shock temperature (ΔT) of monolithic alumina was 400 C. However, it decreased to 300 C for alumina incorporating only AlTiC master alloys, and increased with further addition of diopside and rare earths. Improvement of thermal shock resistance was obtained for alumina ceramic composites containing 9.5 wt.% AlTiC master alloys and 0.5 wt.% rare earth additions, which was mainly attributed to the formation of elongated grains in the composites.

  4. Spectroscopic properties of rare earths in optical materials

    CERN Document Server

    Parisi, Jürgen; Osgood, R; Warlimont, Hans; Liu, Guokui; Jacquier, Bernard

    2005-01-01

    Aimed at researchers and graduate students, this book provides up-to-date information for understanding electronic interactions that impact the optical properties of rare earth ions in solids. Its goal is to establish a connection between fundamental principles and the materials properties of rare-earth activated luminescent and laser optical materials. The theoretical survey and introduction to spectroscopic properties include electronic energy level structure, intensities of optical transitions, ion-phonon interactions, line broadening, and energy transfer and up-conversion. An important aspect of the book lies in its deep and detailed discussions on materials properties and the potential of new applications such as optical storage, information processing, nanophotonics, and molecular probes that have been identified in recent experimental studies. This volume will be a valuable reference book on advanced topics of rare earth spectroscopy and materials science.

  5. Study On The Separation And Extraction Of Rare-Earth Elements From The Phosphor Recovered From End Of Life Fluorescent Lamps

    Directory of Open Access Journals (Sweden)

    Shin D.-W.

    2015-06-01

    Full Text Available In this study, recovered phosphor from end of life three-wavelength fluorescent lamp was selected for reuse rare earth elements in the phosphor. The effect of a type of acid, concentration, and time was investigated as solubility of rare earth elements. In addition, precipitate heat-treated was investigated as possibility of reusable phosphor. The results showed that the amount of the rare earth elements was different values depending on the type of acid, and it was investigated with concentration of acid and reaction time. After precipitation reaction, the precipitate was sintered in electric furnace in order to reuse rare earth elements as phosphor. It was confirmed that yttrium, europium, oxygen, and carbon through X-ray diffraction and inductively coupled plasma analysis. Following the results, it can assume that rare earth oxide reuse the phosphor as three-wavelength fluorescent lamp.

  6. Rare-Earth Elements in Lighting and Optical Applications and Their Recycling

    Science.gov (United States)

    Song, Xin; Chang, Moon-Hwan; Pecht, Michael

    2013-10-01

    Rare-earth elements (REEs) are used in lighting and optical applications to enable color and light adjustment, miniaturization, and energy efficiency. Common applications of REEs include phosphors for light-emitting diodes, lasers, and electronic video displays. This article reviews how REEs are widely used in these applications. However, supply constraints, including rising prices, environmental concerns over mining and refining processes, and China's control over the supply of the vast majority of REEs, are of concern for manufacturers. In view of these supply constraints, this article discusses ways for manufacturers of lighting and optical devices to identify potential substitutes and recycling methods for REEs.

  7. Direct Reuse of Rare Earth Permanent Magnets—Coating Integrity

    DEFF Research Database (Denmark)

    Høgberg, Stig; Holbøll, Joachim; Mijatovic, Nenad

    2017-01-01

    Rare earth permanent magnets can be reused directly as an alternative to traditional recycling methods, in which scrapped magnets are reprocessed into new magnets by undergoing many of the original energy-intensive and expensive production processes. Direct reuse entails using segmented magnet...... assemblies built by several small standard-sized magnets that can be reused directly in a number of different applications. A central part of the direct reuse strategy is to separate and demagnetize magnets by heating them to the Curie temperature. We investigated the validity of direct reuse as a rare earth...

  8. Rare earth element abundances in presolar SiC

    Science.gov (United States)

    Ireland, T. R.; Ávila, J. N.; Lugaro, M.; Cristallo, S.; Holden, P.; Lanc, P.; Nittler, L.; Alexander, C. M. O'D.; Gyngard, F.; Amari, S.

    2018-01-01

    Individual isotope abundances of Ba, lanthanides of the rare earth element (REE) group, and Hf have been determined in bulk samples of fine-grained silicon carbide (SiC) from the Murchison CM2 chondrite. The analytical protocol involved secondary ion mass spectrometry with combined high mass resolution and energy filtering to exclude REE oxide isobars and Si-C-O clusters from the peaks of interest. Relative sensitivity factors were determined through analysis of NIST SRM reference glasses (610 and 612) as well as a trace-element enriched SiC ceramic. When normalised to chondrite abundances, the presolar SiC REE pattern shows significant deficits at Eu and Yb, which are the most volatile of the REE. The pattern is very similar to that observed for Group III refractory inclusions. The SiC abundances were also normalised to s-process model predictions for the envelope compositions of low-mass (1.5-3 M⊙) AGB stars with close-to-solar metallicities (Z = 0.014 and 0.02). The overall trace element abundances (excluding Eu and Yb) appear consistent with the predicted s-process patterns. The depletions of Eu and Yb suggest that these elements remained in the gas phase during the condensation of SiC. The lack of depletion in some other moderately refractory elements (like Ba), and the presence of volatile elements (e.g. Xe) indicates that these elements were incorporated into SiC by other mechanisms, most likely ion implantation.

  9. Recovery of rare earths from spent NdFeB magnets of wind turbine: Leaching and kinetic aspects.

    Science.gov (United States)

    Kumari, Aarti; Sinha, Manish Kumar; Pramanik, Swati; Sahu, Sushanta Kumar

    2018-01-31

    Increasing demands of rare earth (RE) metals for advanced technological applications coupled with the scarcity of primary resources have led to the development of processes to treat secondary resources like scraps or end of life products that are often rich in such metals. Spent NdFeB magnet may serve as a potential source of rare earths containing around ∼30% of neodymium and other rare earths. In the present investigation, a pyro-hydrometallurgical process has been developed to recover rare earth elements (Nd, Pr and Dy) from the spent wind turbine magnet. The spent magnet is demagnetized and roasted at 1123 K to convert rare earths and iron to their respective oxides. Roasting of the magnet not only provides selectivity, but enhances the leaching efficiency also. The leaching of the roasted sample with 0.5 M hydrochloric acid at 368 K, 100 g/L pulp density and 500 rpm for 300 min selectively recovers the rare earth elements almost quantitatively leaving iron oxide in the residue. Leaching of rare earth elements with hydrochloric acid follows the mixed controlled kinetic model with activation energy (E a ) of 30.1 kJ/mol in the temperature range 348-368 K. The leaching mechanism is further established by characterizing the leach residues obtained at different time intervals by scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Individual rare earth elements from the leach solution containing 16.8 g/L of Nd, 3.8 g/L Pr, 0.28 g/L of Dy and other minor impurity elements could be separated by solvent extraction. However, mixed rare earth oxide of 99% purity was produced by oxalate precipitation followed by roasting. The leach residue comprising of pure hematite has a potential to be used as pigment or can find other applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Global demand for rare earth resources and strategies for green mining.

    Science.gov (United States)

    Dutta, Tanushree; Kim, Ki-Hyun; Uchimiya, Minori; Kwon, Eilhann E; Jeon, Byong-Hun; Deep, Akash; Yun, Seong-Taek

    2016-10-01

    Rare earth elements (REEs) are essential raw materials for emerging renewable energy resources and 'smart' electronic devices. Global REE demand is slated to grow at an annual rate of 5% by 2020. This high growth rate will require a steady supply base of REEs in the long run. At present, China is responsible for 85% of global rare earth oxide (REO) production. To overcome this monopolistic supply situation, new strategies and investments are necessary to satisfy domestic supply demands. Concurrently, environmental, economic, and social problems arising from REE mining must be addressed. There is an urgent need to develop efficient REE recycling techniques from end-of-life products, technologies to minimize the amount of REEs required per unit device, and methods to recover them from fly ash or fossil fuel-burning wastes. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Investigation of recovery and recycling of rare earth elements from waste fluorescent lamp phosphors

    Science.gov (United States)

    Eduafo, Patrick Max

    Characterization techniques and experimental measurements were used to evaluate a process for recycling rare earth elements (REEs) from spent fluorescent lamp phosphors. QEMSCAN analysis revealed that over 60% of the rare earth bearing minerals was less than 10 microm. A representative sample of the as-received feed contained 14.59 wt% total rare earth elements (TREE) and upon sieving to below 75 microm, the grade increased to 19.60 wt% REE with 98.75% recovery. Based on experimental work, a new process for extracting the chief REEs from end of life fluorescent lamps has been developed. The proposed flowsheet employs a three-stage leaching and precipitation process for selective extraction and recovery of the REEs. Hydrochloric acid was used as lixiviant in batch leach experiments on the phosphor powder. The maximum extraction obtained was 100% for both yttrium and europium under the following leaching conditions: 2.5 M HCl, 70°C, 1 hour, 180 g/L and 600 rpm. However, the solubility of cerium, lanthanum and terbium remained low at these conditions. Kinetic data of the leaching of yttrium and europium showed best fit to the logarithmic rate expression of the empirical model of leaching. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298 to 343 K. Precipitation tests demonstrate that at least 50% excess the stoichiometric amount of oxalic acid is needed to recover yttrium and europium efficiently to produce a pure (Y, Eu) mixed oxide. Total recovery of the REEs was achieved even at very low pH or without any base added. Over 99% pure mixed rare earth oxide at 99% recovery has been attained. An economic assessment of the developed process using operating and capital cost have be undertaken and based on the analysis of the three economic scenarios, two are economic and one is non-economic.

  12. Complex Electronic Structure of Rare Earth Activators in Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Aberg, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yu, S. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zhou, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-27

    To aid and further the understanding of the microscopic mechanisms behind the scintillator nonproportionality that leads to degradation of the attainable energy resolution, we have developed theoretical and experimental algorithms and procedures to determine the position of the 4f energy levels of rare earth dopants relative to the host band edge states.

  13. Local magnetism in rare-earth metals encapsulated in fullerenes

    NARCIS (Netherlands)

    De Nadai, C; Mirone, A; Dhesi, SS; Bencok, P; Brookes, NB; Marenne, [No Value; Rudolf, P; Tagmatarchis, N; Shinohara, H; Dennis, TJS; Marenne, I.; Nadaï, C. De

    Local magnetic properties of rare-earth (RE) atoms encapsulated in fullerenes have been characterized using x-ray magnetic circular dichroism and x-ray absorption spectroscopy (XAS). The orbital and spin contributions of the magnetic moment have been determined through sum rules and theoretical

  14. THE EFFECTS OF RARE EARTHS ON ACTIVITY AND SURFACE ...

    African Journals Online (AJOL)

    KEY WORDS: Rare earths, Ruthenium-based catalyst, Water gas shift reaction. INTRODUCTION. The water gas shift reaction (WGSR) is one of basic processes in the chemical fertilizer industry and the key step in H2 production by reforming of hydrocarbons for fuel cells. The conventional iron-chromium WGSR catalysts do ...

  15. Upconversion studies in rare earth ions-doped lanthanide materials

    Indian Academy of Sciences (India)

    2014-02-08

    Feb 8, 2014 ... for direct vision applications. There are many applications of rare earth-doped materials. [1,2]. Er3+ ion has low photon absorption coefficient at around 976 nm. The 976 nm laser excitation wavelength is cheaply available and absorption of this wavelength in water is also low. Therefore, many researchers ...

  16. Rare earth point defects in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, S.

    2007-12-14

    In this work we investigate rare earth doped GaN, by means of theoretical simulations. The huge unit cells necessary to model the experimental system, where dilute amount of rare earth ions are used, are handled with the charge self consistent density-functional based-tight binding (SCC-DFTB) calculational scheme. The method has been extended to include LDA+U and simplified self interaction corrected (SIC)-like potentials for the simulation of systems with localised and strongly correlated electrons. A set of tight-binding parameters has been created to model the interaction of GaN with some dopants, including a selection of lanthanide ions interesting due to their optical or magnetic properties (Pr, Eu, Gd, Er and Tm). The f-electrons were treated as valence electrons. A qualitatively correct description of the band gap is crucial for the simulation of rare earth doped GaN, because the luminescence intensity of the implanted samples depends on the size of the host band gap and because the rare earths could introduce charge transition levels near the conduction band. In this work these levels are calculated with the Slater-Janak (SJ) transition state model, which allows an approximate calculation of the charge transition levels by analysing the Kohn-Sham eigenvalues of the DFT. (orig.)

  17. Preliminary investigation of the rare earth element (REE ...

    African Journals Online (AJOL)

    Shales belonging to the Oshosun Formation exposed at the Sagamu quarry of the West African Portland Cement have been mapped and assessed for their abundances in rare earth elements (REE). The shale thickness, which measures approximately 15m and overlies the Ewekoro Formation is separated by a very thin ...

  18. Rare earth element behaviour in zironc-melt systems

    NARCIS (Netherlands)

    Hanchar, John M.; van Westrenen, W.

    2007-01-01

    Natural zircon crystals incorporate rare earth elements (REE) into their structure at concentrations determined by the pressure, temperature, and composition of their growth environment. In principle, REE concentrations in magmatic zircon crystals can be used to infer their conditions of growth and

  19. Dissolved rare earth elements in the Black Sea

    NARCIS (Netherlands)

    Schijf, Johan; Baar, Hein J.W. de; Wijbrans, Jan R.; Landing, William M.

    1991-01-01

    Concentrations of rare earths in the deep anoxic Black Sea are about one order of magnitude higher than in normal open ocean waters. From a minimum at the suboxic-anoxic interface at about 107 m depth, concentrations increase strongly to a maximum at about 300–400 m depth. Concentrations of Ce range

  20. Mother Lode: The Untapped Rare Earth Mineral Resources of Vietnam

    Science.gov (United States)

    2013-11-01

    and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any...Marc Humphries . CRS Report R41347. Washington, DC: Office of Congressional Information and Publishing, June 8, 2012. ―. Rare Earth Elements in

  1. Determination of rare earth and refractory trace element ...

    Indian Academy of Sciences (India)

    Experimental and analytical procedures devised for measurement of rare earth element (REE) abundances using a secondary ion mass spectrometer (ion microprobe) are described. This approach is more versatile than the conventional techniques such as neutron activation analysis and isotope dilution mass spectrometry ...

  2. Systematic hardness measurements on some rare earth garnet ...

    Indian Academy of Sciences (India)

    Unknown

    microwave and magnetic bubble devices. When doped with Nd, some of the rare earth garnets act as excellent laser hosts. Their photoemission spectra are ..... Grants Commission, New Delhi, for financial support by way of an emeritus fellowship. References. Chin G Y 1975a Deformation of ceramic materials (New York:.

  3. An introduction to the economics of rare earths

    NARCIS (Netherlands)

    Bartekova, E.

    2014-01-01

    The aim of this paper is to examine the supply risk of rare earths and its impact on low carbon technologies deployment. Bringing together seemingly disconnected strands of scientific literature, this multidisciplinary approach allows to provide an overarching overview of the economics of rare

  4. Facile and Efficient Decontamination of Thorium from Rare Earths Based on Selective Selenite Crystallization.

    Science.gov (United States)

    Wang, Yaxing; Lu, Huangjie; Dai, Xing; Duan, Tao; Bai, Xiaojing; Cai, Yawen; Yin, Xuemiao; Chen, Lanhua; Diwu, Juan; Du, Shiyu; Zhou, Ruhong; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Liu, Ning; Wang, Shuao

    2018-02-19

    The coexistence of radioactive contaminants (e.g., thorium, uranium, and their daughters) in rare earth minerals introduces significant environmental, economic, and technological hurdles in modern rare earth production. Efficient, low cost, and green decontamination strategies are therefore desired to ameliorate this problem. We report here a single-step and quantitative decontamination strategy of thorium from rare earths based on a unique periodic trend in the formation of crystalline selenite compounds across the lanthanide series, where Ce(III) is fully oxidized in situ to Ce(IV). This gives rise to a crystallization system that is highly selective to trap tetravalent f-blocks while all other trivalent lanthanides completely remain in solution when coexist. These results are bolstered by first-principles calculations of lattice energies and an examination of bonding in these compounds. This system is contrasted with typical natural and synthetic systems, where trivalent and tetravalent f-block elements often cocrystallize. The separation factors after one round of crystallization were determined from binary systems of Th(IV)/La(III), Th(IV)/Eu(III), and Th(IV)/Yb(III) to reach 2.1 × 10 5 , 1.2 × 10 5 , and 9 × 10 4 , respectively. Selective crystallization of thorium from a simulated monazite composite yields a separation factor of 1.9 × 10 3 with nearly quantitative removal of thorium.

  5. Intense luminescence emission from rare-earth-doped MoO3 nanoplates and lamellar crystals for optoelectronic applications

    Science.gov (United States)

    Vila, M.; Díaz-Guerra, C.; Jerez, D.; Lorenz, K.; Piqueras, J.; Alves, E.

    2014-09-01

    Strong and stable room-temperature photoluminescence (PL) emission is achieved in MoO3 nanoplates and lamellar crystals doped with Er and Eu by ion implantation and subsequent annealing. Micro-Raman and PL spectroscopy reveal that optical activation of the rare earth ions and recovery of the original MoO3 structure are achieved for shorter annealing treatments and for lower temperatures in nanoplates, as compared with lamellar crystals. Er seems to be more readily incorporated into optically active sites in the oxide lattice than Eu. The influence of the dimensionality of the host sample on the characteristics of the PL emission of both rare earth dopants is addressed.

  6. Rare Earth-doped Ceria Catalysts for ODHE Reaction in a Catalytic Modified MIEC Membrane Reactor

    OpenAIRE

    Lobera González, Maria Pilar; Balaguer Ramirez, Maria; García Fayos, Julio; Serra Alfaro, José Manuel

    2012-01-01

    An intensification process for the selective oxidation of hydrocarbons integrates a catalytic reactor and an oxygen separation membrane. This work presents the study of oxidative dehydrogenation of ethane at 1123 K in a catalytic membrane reactor based on mixed ionic-electronic conducting (MIEC) membranes. The surface of a membrane made of Ba0.5Sr0.5Co0.8Fe0.2O3-d has been activated using different porous catalytic layers based on rare earth-doped cerias (fluorite structure) and the porous ca...

  7. Effect of annealing on chemical, structural and electrical properties of Au/Gd2O3/n-GaN heterostructure with a high-k rare-earth oxide interlayer

    Science.gov (United States)

    Prasad, C. Venkata; Reddy, M. Siva Pratap; Rajagopal Reddy, V.; Park, Chinho

    2018-01-01

    The chemical, structural and electrical characteristics of a fabricated Au/Gd2O3/n-GaN heterostructure with gadolinium oxide (Gd2O3) as an insulating layer are explored by XPS, XRD and I-V techniques at room temperature and 400 °C annealing. XPS and XRD results reveal that the Gd2O3 films are formed at the interface. The electrical results of heterostructure are correlated with the conventional Au/n-GaN Schottky structure results. The as-deposited and 400 °C annealed heterostructures exhibited excellent rectifying behavior and very low reverse leakage current compared to the Schottky structure. Higher barrier height (BH) and on/off ratio are achieved for the heterostructure compared to the Schottky structure, which has led the barrier height modified by Gd2O3 insulating layer. Also, the results indicate that the BH slightly increases for the 400 °C annealed heterostructures. Further, the BH, ideality factor and series resistance are evaluated by Cheung's, Norde functions and ΨS-V plot and the values are found to be similar with one another that indicates their consistency and validity. In addition, the mechanism of the BH modulation could be explained by feasible energy level band diagrams. These findings indicate that the Gd2O3 films could be a favored dielectric material for the development of metal/insulating/semiconductor devices.

  8. Thermochemistry of Rare Earth Silicates for Environmental Barrier Coatings

    Science.gov (United States)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

    Rare earth silicates are promising candidates as environmental protective coatings (EBCs) for silica-forming ceramics and composites in combustion environments since they are predicted to have lower reactivity with the water vapor combustion products. The reactivity of rare earth silicates is assessed by the thermodynamic activity of the silica component which is best measured by Knudsen effusion mass spectrometry (KEMS). Here, we discuss a novel method based on a reducing agent to increase the partial pressure of SiO(g) which is then used to calculate thermodynamic activity of silica in Y2O3-SiO2 and Yb2O3-SiO2 systems. After the KEMS measurements, samples were probed by X-ray diffraction and their phase content was calculated from Rietveld refinement.

  9. Thermochemical properties of the rare earth complexes with pyromellitic acid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijun; Liu, Fei [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), Shaanxi Key Laboratory of Physico-Inorganic Chemistry, Department of Chemistry, Northwest University, Xi' an 710069 (China); Yang, Xuwu, E-mail: yangxuwu@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), Shaanxi Key Laboratory of Physico-Inorganic Chemistry, Department of Chemistry, Northwest University, Xi' an 710069 (China); Wang, Xiaoyan; Liu, Ruiping; Zhao, Sa; Chen, Sanping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry (Ministry of Education), Shaanxi Key Laboratory of Physico-Inorganic Chemistry, Department of Chemistry, Northwest University, Xi' an 710069 (China)

    2009-06-01

    Fourteen rare earth complexes with pyromellitic acid were synthesized and characterized by means of chemical and elemental analysis, and TG-DTG. The constant-volume combustion energies of complexes, {Delta}{sub c}U, were measured by a precise rotating-bomb calorimeter (RBC-type II). Their standard molar enthalpies of combustion, {Delta}{sub c}H{sub m}{sup {theta}}, and standard molar enthalpies of formation, {Delta}{sub f}H{sub m}{sup {theta}}, were calculated at T = 298.15 K. The relationship of {Delta}{sub c}H{sub m}{sup {theta}} and {Delta}{sub f}H{sub m}{sup {theta}} with the atomic numbers of the elements in the lanthanide series was examined. The results show that a certain amount of covalence is present in the chemical bond between rare earth cations and the ligand.

  10. Spectroscopic identification of rare earth elements in phosphate glass

    Science.gov (United States)

    Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

    2018-01-01

    In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV–VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

  11. The occurrence of rare earth elements in some Finnish mires

    Directory of Open Access Journals (Sweden)

    Yliruokanen, I.

    1995-12-01

    Full Text Available The content of the more abundant rare earths (RE (Y, La, Ce, Pr, Nd and Sm in the ash of 399 peat samples from 26 Finnish mires was determined by X-ray fluorescence spectrometry. The content of all rare earths (La-Lu, Y in 29 samples was also determined by spark source mass spectrometry. The median RE contents in peat ashes from areas where the bedrock consists of rapakivi granite, granite or archean gneiss are reported. Detailed data concerning the individual mires are also presented. The highest RE contents were found in samples from rapakivi granite areas where a strong negative Eu anomaly was also observed. The RE contents were in general highest at the basal peat layers.

  12. Ionoluminescence of trivalent rare-earth-doped strontium barium niobate

    Energy Technology Data Exchange (ETDEWEB)

    Calvo del Castillo, H. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid, Modulo C-VI, Campus de Cantoblanco, 28049 Cantoblanco, Madrid (Spain); Universidad Nacional Automoma de Mexico, Instituto de Fisica, 04510 Ciudad Universitaria, Mexico D.F. (Mexico); Ruvalcaba, J.L. [Universidad Nacional Automoma de Mexico, Instituto de Fisica, 04510 Ciudad Universitaria, Mexico D.F. (Mexico); Bettinelli, M.; Speghini, A. [Dipartimento Scientifico e Tecnologico, Universita di Verona and INSTM, UdR Verona, Ca Vignal, Strada Le Grazie 15, I-37134 Verona (Italy); Barboza Flores, M. [Centro de Investigacion en Fisica, Universidad de Sonora, Hermosillo, Sonora (Mexico); Calderon, T. [Departamento de Geologia y Geoquimica, Universidad Autonoma de Madrid, Modulo C-VI, Campus de Cantoblanco, 28049 Cantoblanco, Madrid (Spain)], E-mail: tomas.calderon@uam.es; Jaque, D.; Garcia Sole, J. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)

    2008-05-15

    Ionoluminescence spectra for different rare-earth ion (Pr{sup 3+} and Eu{sup 3+})-activated Sr{sub x}Ba{sub 1-x}Nb{sub 2}O{sub 6} strontium barium niobate crystals (x=0.33 and 0.60) have been induced with a 3 MeV proton beam for a variety of beam current intensities (45, 40 and 20 nA). The proton-beam induced luminescent spectra have shown features associated with the presence of the rare-earth ion and some spectral features mostly related to the host crystal, which appear only for high beam current intensities. We have compared the ionoluminescence results to those obtained under UV light excitation (photoluminescence technique) where a direct excitation of the band gap would occur.

  13. Electrons and Spin Waves in Heavy Rare Earth Metals

    DEFF Research Database (Denmark)

    Mackintosh, A. R.

    1972-01-01

    Although the main principles governing the magnetic interactions and magnetic ordering in rare earth metals have been qualitatively understood for some time, it is only relatively recently that a sufficiently detailed study has been made of their electronic and magnetic excitations to place...... this understanding on a more quantitative basis. The experimental evidence on the electronic structure of the rare earths is still rather meager but, so far as it goes, is in accord with the detailed description provided by band structure calculations. On the other hand, the experimental study of the magnon...... dispersion relations by inelastic neutron scattering has provided a wealth of information about the interactions between the local moments, associated with the incompletely filled 4f subshell, and the rest of the crystal. The main emphasis in these notes will be on the interrelation between the electronic...

  14. Characterization of Rare Earth Element Minerals in Coal Utilization Byproducts

    Energy Technology Data Exchange (ETDEWEB)

    Montross, Scott N. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Verba, Circe A. [National Energy Technology Lab. (NETL), Albany, OR (United States). Research Innovation Center; Collins, Keith [National Energy Technology Lab. (NETL), Albany, OR (United States). Research Innovation Center

    2017-07-17

    The United States currently produces over 100 million tons of coal utilization byproducts (CUB) per year in the form of fly ash, bottom ash, slag, and flue gas (American Coal Ash Association (ACCA), 2015). But this “waste material” also contains potentially useful levels of rare earth elements (REE). Rare earth elements are crucial for many existing and emerging technologies, but the U.S. lacks a domestic, sustainable REE source. Our project explored the possibility of developing a supply of REEs for U.S. technologies by extracting REEs from CUBs. This work offers the potential to reduce our dependence on other countries for supply of these critical elements (NETL, REE 2016 Project Portfolio). Geologic and diagenetic history, industrial preparation methods, and the specific combustion process all play major roles in the composition of CUB. During combustion, inorganic mineral phases of coal particles are fluidized at temperatures higher than 1400oC, so inorganic mineral materials are oxidized, fused, disintegrated, or agglomerated into larger spherical and amorphous (non-crystalline) particles. The original mineralogy of the coal-containing rock and heating/cooling of the material significantly affects the composition and morphology of the particles in the combustion byproduct (Kutchko and Kim, 2006). Thus, different types of coal/refuse/ash must be characterized to better understand mineral evolution during the combustion process. Our research focused on developing a working model to address how REE minerals behave during the combustion process: this research should help determine the most effective engineering methods for extracting REEs from CUBs. We used multimodal imaging and image processing techniques to characterize six rock and ash samples from different coal power plants with respect to morphology, grain size, presence of mineral phases, and elemental composition. The results of these characterization activities provided thresholds for realizing the

  15. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    OpenAIRE

    DeVol, Timothy A.; Basak Yazgan-Kukouz; Baris Kokuoz; DiMaio, Jeffrey R.; Sprinkle, Kevin B.; Tiffany L. James; Courtney J. Kucera; Luiz G. Jacobsohn; John Ballato

    2010-01-01

    This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE) doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP) that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminesc...

  16. Syntheses and structural properties of rare earth carbodiimides.

    Science.gov (United States)

    Neukirch, Michael; Tragl, Sonja; Meyer, H-Jürgen

    2006-10-02

    Crystalline samples of rare earth carbodiimides were synthesized by solid-state metathesis reactions of rare earth trichlorides with lithium cyanamide in sealed silica ampules. Two distinct structures were determined by single-crystal X-ray diffraction. The structure determined for Sm2(CN2)3 [C2/m, Z = 2, a = 14.534(2) A, b = 3.8880(8) A, c = 5.2691(9) A, beta = 95.96(2) degrees , R1 = 0.0267, and wR2 = 0.0667] was assigned for RE2(CN2)3 compounds with RE = Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, and the structure determined for Lu2(CN2)3 [R32, Z = 3, a = 6.2732(8) A, c = 14.681(2) A, R1 = 0.0208, and wR2 = 0.0526] was assigned for the smallest rare earth ions with RE = Tm, Yb, and Lu by powder X-ray diffraction. Both types of crystal structures are characterized by layers of [NCN](2-) ions whose arrangements can be derived from the motif of a closest packed layer of sticks. These layers alternate with layers of rare earth ions in a one-by-one sequence. Different tilting arrangements of the N-C-N-axes relative to the stacking directions (c) and different arrangements of RE3+ ions within metal atom layers account for the two distinct structures in which Sm3+ and Lu3+ ions adopt the coordination numbers 7 and 6, respectively.

  17. Implications of Competition for Rare Earth Elements (REE) in Africa

    Science.gov (United States)

    2011-03-15

    Reef of the Bushveld Complex have shown trace element patterns in magma flows for some REEs. However, further exploratory mining is required to...rare earth element mine located in the Mojave Desert at Mountain Pass, California. The Transitional era lasted from 1985 to 1991 as global dominance...shocking data. For example, the PMCP’s report entitled Resources for Freedom showed that consumption rates for coal rose by two hundred and fifty

  18. Growth of oriented rare-earth-transition-metal thin films

    Energy Technology Data Exchange (ETDEWEB)

    Fullerton, E.E.; Sowers, C.H.; Bader, S.D. [Argonne National Lab., IL (United States); Wu, X.Z. [Argonne National Lab., IL (United States)]|[Northern Illinois Univ., DeKalb, IL (United States)

    1996-04-01

    Rare-earth-transition-metal thin films are successfully grown by magnetron sputtering onto single-crystal MgO substrates with epitaxial W buffer layers. The use of epitaxial W buffer layers allows oriented single-phase films to be grown. Sm-Co films grown onto W(100), have strong in-plane anisotropy and coercivities exceeding 5 T at 5 K whereas Fe-Sm films have strong perpendicular anisotropy and are magnetically soft.

  19. Rare Earth Borohydrides—Crystal Structures and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Christoph Frommen

    2017-12-01

    Full Text Available Rare earth (RE borohydrides have received considerable attention during the past ten years as possible hydrogen storage materials due to their relatively high gravimetric hydrogen density. This review illustrates the rich chemistry, structural diversity and thermal properties of borohydrides containing RE elements. In addition, it highlights the decomposition and rehydrogenation properties of composites containing RE-borohydrides, light-weight metal borohydrides such as LiBH4 and additives such as LiH.

  20. THE EFFECTS OF RARE EARTHS ON ACTIVITY AND SURFACE ...

    African Journals Online (AJOL)

    A series of Ru-RE/γ-AL2O3 (RE = Ce, Pr, La, Sm, Tb or Gd) and Ru/γ-AL2O3 catalysts were prepared by impregnation method. The influence of rare earths on the catalytic performance of Ru/γ-AL2O3 catalyst for the water gas shift reaction was studied. The catalysts were characterized by X-ray diffraction (XRD), ...

  1. Synthesis and study of double sodium rare earth vanadates (3)

    Energy Technology Data Exchange (ETDEWEB)

    Molodkin, A.K.; Bogatov, Yu.Eh.; Moskalenko, V.I.; Remizov, V.G.; Skorikov, V.M.; Belan, V.N.; Kurilkin, V.V.; Golik, G.D. (Universitet Druzhby Narodov, Moscow (USSR))

    1982-04-01

    The method of solid-phase synthesis has been used to prepare the double vanadates (3) of rare earths with sodium of the Na/sub 3/Ln(VO/sub 3/)/sub 2/ composition, where Ln=Y, La, Nd-Lu. Thermal stability of synthesized compounds in the air is studied. Infrared spectroscopic investigations testify that in the crystalline lattice vanadium is coordinated with 6 atoms of oxygen.

  2. An Integrated Rare Earth Elements Supply Chain Strategy

    Science.gov (United States)

    2011-02-24

    of the Master of Strategic Studies Degree. The views expressed in this student academic research paper are those of the author and do not reflect...U.S. Secretary of Education and the Council for Higher Education Accreditation. The views expressed in this student academic research paper are...Resource Transformation Act of 2010 – S. 3521, Section 2. Findings. LexisNexis Congressional (accessed November 24, 2010). 26 Mark Humphries, Rare Earth

  3. Social and Environmental Impact of the Rare Earth Industries

    Directory of Open Access Journals (Sweden)

    Saleem H. Ali

    2014-02-01

    Full Text Available The use of rare earth elements in various technologies continues to grow despite some alternatives being found for particular uses. Given a history of ecological concerns about pollution from rare earth mines, particularly in China, there are growing social and environmental concerns about the growth of the mining and mineral processing in this sector. This is best exemplified by the recent social and environmental conflict surrounding the development of the Lynas Advanced Materials Plant (LAMP in Kuantan, Malaysia which led to international activism and claims of environmental and social injustice. This paper analyses the structure of environmental and social conflicts surrounding rare earth minerals and opportunities for improving the social and environmental performance of the sector. Many of these elements are used for green technologies. Opportunities exist that offer a more circular supply chain following industrial ecological principles through which reuse and recycling of the materials can provide a means of mitigating social and environmental conflicts in this sector. In addition, public engagement processes that recognize community concerns about radiation, and transparent scientifically predicated decision-making through an appropriate governance structure within regulatory organizations are also presented.

  4. Uncovering the end uses of the rare earth elements.

    Science.gov (United States)

    Du, Xiaoyue; Graedel, T E

    2013-09-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging and conventional established technologies. However, quantitative knowledge of REE remains sparse, despite the current heightened interest in future availability of the resources. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supply vulnerable to short term disruption. We have drawn upon the published literature and unpublished materials in different languages to derive the first quantitative annual domestic production by end use of individual rare earth elements from 1995 to 2007. The information is illustrated in Sankey diagrams for the years 1995 and 2007. Other years are available in the supporting information. Comparing 1995 and 2007, the production of the rare earth elements in China, Japan, and the US changed dramatically in quantities and structure. The information can provide a solid foundation for industries, academic institutions and governments to make decisions and develop strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Pilot-scale recovery of rare earths and scandium from phosphogypsum and uranium leachates

    Directory of Open Access Journals (Sweden)

    Mashkovtsev Maxim

    2016-01-01

    Full Text Available Ural Federal University (UrFU and VTT have performed joint research on development of industrial technologies for the extraction of REM and Scandium compounds from phosphogypsum and Uranium ISL leachate solutions. Leaching-absorption experiments at UrFU have been supported with multicomponent solution modelling by VTT. The simulations have been performed with VTT’s ChemSheet/Balas program and can be used for speciation calculations in the lixiviant solution. The experimental work combines solvent extraction with advanced ion exchange methodology in a pilot facility capable of treating 5 m3 solution per hour. Currently, the plant produces cerium carbonate, lanthanum oxide, neodymium oxide and concentrate of heavy rare earth metals. A batch of 45 t solids has been processed with the gain of 100 kg’s of REM concentrate. A mini-pilot plant with productivity above 50 liters per hour has been applied to recover scandium oxide and REE concentrates from the uranium ISL solution. As the preliminary product contains radioactivity (mainly strontium, an additional decontamination and cleaning of both concentrates by extraction has rendered a necessity. Finally a purified 99% concentrate of scandium oxide as well as 99% rare earth concentrate are received.

  6. Crystal Fields in Dilute Rare-Earth Metals Obtained from Magnetization Measurements on Dilute Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.

    1974-01-01

    Crystal field parameters of Tb, Dy, and Er in Sc, Y, and Lu are summarized. These parameters are obtained from magnetization measurements on dilute single crystals, and successfully checked by a number of different methods. The crystal field parameters vary unpredictably with the rare-earth solute....... B40, B60, and B66 are similar in Y and Lu. Crystal field parameters for the pure metals Tb, Dy, and Er are estimated from the crystal fields in Y and Lu....

  7. Transferred hyperfine interaction between the rare-earth ions and the fluorine nuclei in rare-earth trifluorides

    DEFF Research Database (Denmark)

    Hansen, P. E.; Nevald, Rolf; Guggenheim, H. G.

    1978-01-01

    The isotropic and anisotropic transferred hyperfine interactions between F ions in the two chemically inequivalent sites and the rare-earth ions (R) have been derived from 19F NMR measurements in the temperature region 100-300 K on single crystals of TbF3 and DyF3. The isotropic interactions are ...... to vary only slightly with temperature. They are further assigned to definite R's in the unit cell, which cannot be done from macroscopic magnetic measurements....

  8. Radiation defects in oxide crystals doped with rare earth ions

    NARCIS (Netherlands)

    Matkovskii, A; Durygin, A; Suchocki, A; Sugak, D; Wallrafen, F; Vakiv, M

    1999-01-01

    The nature of stable and transient color centers in Y3Al5O12, Gd3Ca5O12, YAlO3 and LiNbO3 crystals is studied. The color centers are created by various types of irradiation. The effect of irradiation on crystal optical properties in visible and ultraviolet range is presented.

  9. Associative correlations between TH and U and rare earth elements in the living matter

    OpenAIRE

    Коваль, Е. В.; Барановская, Наталья Владимировна

    2016-01-01

    The article introduces the results of studying the correlations between radioactive and rare earth elements in living matter of the Tomsk region. Peculiarities in the distribution of districts for ratios of radioactive elements in the rare earth elements.

  10. Wheat leaves emit nitrous oxide during nitrate assimilation.

    Science.gov (United States)

    Smart, D R; Bloom, A J

    2001-07-03

    Nitrous oxide (N(2)O) is a key atmospheric greenhouse gas that contributes to global climatic change through radiative warming and depletion of stratospheric ozone. In this report, N(2)O flux was monitored simultaneously with photosynthetic CO(2) and O(2) exchanges from intact canopies of 12 wheat seedlings. The rates of N(2)O-N emitted ranged from microorganisms on root surfaces and emitted in the transpiration stream. In vitro production of N(2)O by both intact chloroplasts and nitrite reductase, but not by nitrate reductase, indicated that N(2)O produced by leaves occurred during photoassimilation of NO(2)(-) in the chloroplast. Given the large quantities of NO(3)(-) assimilated by plants in the terrestrial biosphere, these observations suggest that formation of N(2)O during NO(2)(-) photoassimilation could be an important global biogenic N(2)O source.

  11. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction

    OpenAIRE

    Cramer, Alisha J.; Cole, Jacqueline M.; Fitzgerald, Vicky; Honkimaki, Veijo; Roberts, Mark A.; Brennan, Tessa; Martin, Richard A.; Saunders, George A.; Newport, Robert J.

    2013-01-01

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3) x(R�2O3)y(P2O 5)1-(x+y), where (R, R�) denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP 5O14. Thereupon, the effects of rare-earth co-dopin...

  12. Propagation of magnetostatic modes on aperiodic rare-earth multilayers

    Science.gov (United States)

    Santiago, F. A. L.; Anselmo, D. H. A. L.; Almeida, N. S.; Vasconcelos, M. S.; Cottam, M. G.; Mello, V. D.

    2018-01-01

    The localization behavior and scaling properties of magnetostatic modes propagating on magnetic aperiodic superlattices made up by rare-earth materials is analyzed. Both surface and bulk modes are obtained, considering two different aperiodic rules of stacking: Thue-Morse and Fibonacci. The magnetization is considered to be perpendicular to the superlattice's interfaces. Our model consider as magnetic materials both dysprosium and holmium, at different temperatures. A scaling behavior is observed for the allowed bulk bands, through specific ordering parameters, meaning that the allowed bands have a fractal (or multifractal) structure.

  13. Resonance electronic Raman scattering in rare earth crystals

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G.M.

    1988-11-10

    The intensities of Raman scattering transitions between electronic energy levels of trivalent rare earth ions doped into transparent crystals were measured and compared to theory. A particle emphasis was placed on the examination of the effect of intermediate state resonances on the Raman scattering intensities. Two specific systems were studied: Ce/sup 3 +/(4f/sup 1/) in single crystals of LuPO/sub 4/ and Er/sup 3 +/(4f/sup 11/) in single crystals of ErPO/sub 4/. 134 refs., 92 figs., 33 tabs.

  14. Small hole polarons in rare-earth titanates

    Energy Technology Data Exchange (ETDEWEB)

    Bjaalie, L.; Moetakef, P.; Cain, T. A.; Janotti, A.; Himmetoglu, B.; Stemmer, S.; Van de Walle, C. G. [Materials Department, University of California Santa Barbara, California 91306-5050 (United States); Ouellette, D. G.; Allen, S. J. [Department of Physics, University of California, Santa Barbara, California 91306-5050 (United States)

    2015-06-08

    We investigate the behavior of hole polarons in rare-earth titanates by combining optical conductivity measurements with first-principles hybrid density functional calculations. Sr-doped GdTiO{sub 3} (Gd{sub 1−x}Sr{sub x}TiO{sub 3}) was grown by molecular beam epitaxy. We show that a feature in the optical conductivity that was previously identified with the Mott-Hubbard gap is actually associated with the excitation of a small polaron. The assignment is based on an excellent match between the experimental spectra and first-principles calculations for polaron excitation mechanisms.

  15. Optical Properties of Rare Earth Doped SrS Phosphor: A Review

    Science.gov (United States)

    Khare, Ayush; Mishra, Shubhra; Kshatri, D. S.; Tiwari, Sanjay

    2017-02-01

    Rare earth (RE) doped SrS phosphor has attracted a lot of attention on a wide range of photo-, cathodo-, thermo-, and electroluminescent applications. Upon doping with different RE elements (e.g., Ce, Pr, Eu, Yb), the luminescence from SrS can be varied over the entire visible region by appropriately choosing the composition of the strontium sulfide host. The main applications include flat panel displays and SrS-based powder electroluminescence (EL) for back lights. Sulfide materials known for providing Eu2+ based red emission band and preferred as a color conversion material in white light emitting diodes are discussed. Especially, the applications of RE doped SrS are described in light of their utility as conversion and storage phosphors. The effect of energy level splitting, EL efficiency, post-annealing, milling time, and impurity on luminescence properties for SrS are also discussed.

  16. Investigation on the status of rare earth elements contained in the powder of spent fluorescent lamps

    Energy Technology Data Exchange (ETDEWEB)

    Belardi, G. [Institute of Environmental Geology and Geoengineering (CNR) Area della Ricerca CNR, via Salaria km 29300, Monterotondo, Rome 00016 (Italy); Ippolito, N. [Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, via Eudossiana 84, Rome 00184 (Italy); Piga, L., E-mail: luigi.piga@uniroma1.it [Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, via Eudossiana 84, Rome 00184 (Italy); Serracino, M. [Institute of Environmental Geology and Geoengineering (CNR) Area della Ricerca CNR, via Salaria km 29300, Monterotondo, Rome 00016 (Italy)

    2014-09-10

    Highlights: • Most of rare earth elements are contained in particles of size finer than 7 μm. • Most of Si, K and Na are contained in the coarser size-fractions. • The phases in the size-fractions of the fluorescent powder have been determined. • Europium is contained in yttrium oxide and in vanadium–yttrium oxides. • The crystallo–chemical composition of all the phases has been determined. - Abstract: The aim of this study is to examine the status of rare earth elements (REE) contained in the chemical compounds that make up the powder of spent fluorescent lamps, with a view of their recovery. The status of REE in the as-received powder, as well as in a few size-class fractions of it, has been established. This way, only those size-class fractions containing high REE concentrations can be considered in a recovery process. The investigation has been carried out using particle-size, chemical, TGA/DTA, XRPD, SEM-EDS and EMPA analyses. The last technique enabled to establish the status of REE within the lattice of the chemical compounds present in the powder. The fineness of the as-received powder and the higher REE concentration in the finest size-classes suggest that physical methods of separation should not be used to separate the REE-containing chemical compounds from each other. Leaching methods seem more suitable with a material of such size.

  17. Spectroscopic Data for Neutral and Ionized Rare Earth Elements

    Science.gov (United States)

    Lawler, J. E.; den Hartog, E. A.; Sneden, C.

    2005-05-01

    The spectra of neutral and ionized rare earth elements have been receiving renewed attention from laboratory spectroscopists during recent years. These efforts have been motivated by data needs of the astrophysics and lighting research communities. In astrophysics studies of metal-poor Galactic halo stars are providing a deeper understanding of the origins of heavy elements, of the chemical evolution of the Galaxy, and some insights into the rapid and slow neutron-capture mechanisms. Rare earth elements are widely used in Metal Halide High Intensity Discharge lamps. The superior performance of such lamps has motivated further development of these devices. Basic spectroscopic data are needed for modeling and diagnosing new lamp designs. This paper reviews progress on determining atomic transition probabilities for neutral and singly ionized rare elements. The most widely used experimental method involves combining radiative lifetimes from laser induced fluorescence measurements, with emission branching fractions from Fourier transform spectra. Theoretical methods for determining atomic transition probabilities have also been improved in recent years. Progress on hyperfine structure and isotopic data is also discussed in this paper.

  18. Rare-earth doped (alpha'/beta')-sialon ceramics

    CERN Document Server

    Gajum, N R

    2001-01-01

    combination of light and heavy rare-earth (Yb-Nd and Gd-Nd), and then pressureless sintered and compared with the single cation materials. Materials in the as sintered state were composed of a high alpha' sialon content with a minor amount of beta' sialon and 12H A1N polytype indicating that the heavy rare-earth (which is the principal alpha' stabilizer) has a dominant effect although EDAX analysis confirmed the presence of both cations (light and heavy) within the alpha' structure. The research also compared, and developed an understanding of, the thermal stability of alpha'-sialon using single Yb or mixed cations. The Yb single cation alpha'/beta' materials exhibited excellent stability over a range of temperature (1200 - 1600 deg C) and for different periods of time up to 168 hrs. The heat treatments result in the crystallisation of the residual phase as a Yb garnet phase which formed at approx 1300 deg C. The mixed cation alpha'/beta' materials showed some alpha'-beta' transformation. The transformation w...

  19. Magnetic and Magnetoelectric Properties of Rare Earth Molybdates

    Directory of Open Access Journals (Sweden)

    B. K. Ponomarev

    2012-01-01

    Full Text Available We present results on ferroelectric, magnetic, magneto-optical properties and magnetoelectric effect of rare earth molybdates (gadolinium molybdate, GMO, and terbium molybdate, TMO, and samarium molybdate, SMO, belonging to a new type of ferroelectrics predicted by Levanyuk and Sannikov. While cooling the tetragonal β-phase becomes unstable with respect to two degenerate modes of lattice vibrations. The β-β′ transition is induced by this instability. The spontaneous polarization appears as a by-product of the lattice transformation. The electric order in TMO is of antiferroelectric type. Ferroelectric and ferroelastic GMO and TMO at room temperature are paramagnets. At low temperatures GMO and TMO are antiferromagnetic with the Neel temperatures TN=0.3 K (GMO and TN=0.45 K (TMO. TMO shows the spontaneous destruction at 40 kOe magnetic field. Temperature and field dependences of the magnetization in TMO are well described by the magnetism theory of singlets at 4.2 K ≤ T ≤ 30 K. The magnetoelectric effect in SMO, GMO and TMO, the anisotropy of magnetoelectric effect in TMO at T = (1.8–4.2 K, the Zeeman effect in TMO, the inversion of the electric polarization induced by the laser beam are discussed. The correlation between the magnetic moment of rare earth ion and the magnetoelectric effect value is predicted. The giant fluctuations of the acoustic resonance peak intensity near the Curie point are observed.

  20. Bacterial Cell Surface Adsorption of Rare Earth Elements

    Science.gov (United States)

    Jiao, Y.; Park, D.; Reed, D.; Fujita, Y.; Yung, M.; Anderko, A.; Eslamimanesh, A.

    2015-12-01

    Rare earth elements (REE) play a critical role in many emerging clean energy technologies, including high-power magnets, wind turbines, solar panels, hybrid/electric vehicle batteries and lamp phosphors. In order to sustain demand for such technologies given current domestic REE shortages, there is a need to develop new approaches for ore processing/refining and recycling of REE-containing materials. To this end, we have developed a microbially-mediated bioadsorption strategy with application towards enrichment of REE from complex mixtures. Specifically, the bacterium Caulobacter crescentus was genetically engineered to display lanthanide binding tags (LBTs), short peptides that possess high affinity and specificity for rare earth elements, on its cell surface S-layer protein. Under optimal conditions, LBT-displayed cells adsorbed greater than 5-fold more REE than control cells lacking LBTs. Competition binding experiments with a selection of REEs demonstrated that our engineered cells could facilitate separation of light- from heavy- REE. Importantly, binding of REE onto our engineered strains was much more favorable compared to non-REE metals. Finally, REE bound to the cell surface could be stripped off using citrate, providing an effective and non-toxic REE recovery method. Together, this data highlights the potential of our approach for selective REE enrichment from REE containing mixtures.

  1. Coal fly ash as a resource for rare earth elements.

    Science.gov (United States)

    Franus, Wojciech; Wiatros-Motyka, Małgorzata M; Wdowin, Magdalena

    2015-06-01

    Rare earth elements (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many elements, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare earth element content. All the fly ashes have a broadly similar distribution of rear earth elements, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67-93, 2012) classification can be considered promising REE raw materials.

  2. Rare Earth Element Concentrations in Brazilian Benchmark Soils

    Directory of Open Access Journals (Sweden)

    Ygor Jacques Agra Bezerra da Silva

    Full Text Available ABSTRACT: Studies regarding background concentrations of rare earth elements (REEs are scarce and have mainly focused on a limited number of soil types from the northern hemisphere. The aim of this study was to determine REE concentrations in thirty-five benchmark soils of Brazil. Composite soil samples were taken from areas under native vegetation or with minimal anthropogenic influence. Concentrations of La, Ce, Pr, Nd, Sm, Eu, Gd, Yb, Lu, Dy, Er, Ho, Tb, Tm, Y, Sc, and Fe were determined by ICP-OES using a cyclonic spray chamber/nebulizer system after microwave acid digestion. Results were assessed by descriptive statistics, Pearson correlation, and principal component analysis (PCA. Regression analyses among Fe, organic carbon, and REEs were performed to provide a tool for estimating REE concentrations in soils. The REE concentrations in the Brazilian benchmark soils were in the following order: Ce > La > Nd > Pr > Y > Sm > Gd > Sc > Dy > Yb > Eu > Er > Tb > Ho > Lu > Tm. The clear decoupling between light and heavy rare earth elements in soils, indicated by multivariate analysis, is mainly related to differences in parent material. The lowest REE concentrations were found in sandy sediments, whereas the highest REE concentrations were observed in basalt, biotite gneiss, and clayey sediments. The organic carbon and Fe concentrations can properly predict REE concentrations in soils; such a finding can assist in estimating REE concentrations in soils not only in Brazil but also in similar soils developed under tropical conditions.

  3. RARE EARTH ELEMENT IMPACTS ON BIOLOGICAL WASTEWATER TREATMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Y.; Barnes, J.; Fox, S.

    2016-09-01

    Increasing demand for rare earth elements (REE) is expected to lead to new development and expansion in industries processing and or recycling REE. For some industrial operators, sending aqueous waste streams to a municipal wastewater treatment plant, or publicly owned treatment works (POTW), may be a cost effective disposal option. However, wastewaters that adversely affect the performance of biological wastewater treatment at the POTW will not be accepted. The objective of our research is to assess the effects of wastewaters that might be generated by new rare earth element (REE) beneficiation or recycling processes on biological wastewater treatment systems. We have been investigating the impact of yttrium and europium on the biological activity of activated sludge collected from an operating municipal wastewater treatment plant. We have also examined the effect of an organic complexant that is commonly used in REE extraction and separations; similar compounds may be a component of newly developed REE recycling processes. Our preliminary results indicate that in the presence of Eu, respiration rates for the activated sludge decrease relative to the no-Eu controls, at Eu concentrations ranging from <10 to 660 µM. Yttrium appears to inhibit respiration as well, although negative impacts have been observed only at the highest Y amendment level tested (660 µM). The organic complexant appears to have a negative impact on activated sludge activity as well, although results are variable. Ultimately the intent of this research is to help REE industries to develop environmentally friendly and economically sustainable beneficiation and recycling processes.

  4. Assessing rare earth elements in quartz rich geological samples.

    Science.gov (United States)

    Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J

    2016-01-01

    Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Antimony film sensor for sensitive rare earth metal analysis in environmental samples.

    Science.gov (United States)

    Makombe, Martin; van der Horst, Charlton; Silwana, Bongiwe; Iwuoha, Emmanuel; Somerset, Vernon

    2016-07-02

    A sensor for the adsorptive stripping voltammetric determination of rare earth elements has been developed. The electrochemical procedure is based on the oxidation of the rare earth elements complexed with alizarin complexone at a glassy carbon electrode that was in situ modified with an antimony film, during an anodic scan from -0.2 V to 1.1 V (vs. Ag/AgCl) and deposition potential of -0.1 V (vs. Ag/AgCl). The factors influencing the adsorptive stripping capability were optimised, including the complexing agent concentration, plating concentration of antimony and deposition time. The detection of rare earth elements (La, Ce and Pr) were realised in 0.08 M sodium acetate (pH = 5.8) solution as supporting electrolyte, with 2 × 10(-6) M alizarin complexone and 1.0 mg L(-1) antimony solution. Under the optimised conditions, a deposition time of 360 s was obtained and a linear response was observed between 1 and 25 µg L(-1). The reproducibility of the voltammetric measurements was found to be within 5.0% RSD for 12 replicate measurements of cerium(III) concentration of 5 µg L(-1) using the same electrode surface. The detection limits obtained using stripping analysis was 0.06, 0.42 and 0.71 μg L(-1) for Ce(III), La(III) and Pr(III), respectively. The developed sensor has been successfully applied for the determination of cerium, lanthanum and praseodymium in municipal tap water samples.

  6. China’s Rare Earths Production Forecasting and Sustainable Development Policy Implications

    Directory of Open Access Journals (Sweden)

    Xibo Wang

    2017-06-01

    Full Text Available Because of their unique physical and chemical properties, Rare earth elements (REEs perform important functions in our everyday lives, with use in a range of products. Recently, the study of China’s rare earth elements production has become a hot topic of worldwide interest, because of its dominant position in global rare earth elements supply, and an increasing demand for rare earth elements due to the constant use of rare earth elements in high-tech manufacturing industries. At the same time, as an exhaustible resource, the sustainable development of rare earth elements has received extensive attention. However, most of the study results are based on a qualitative analysis of rare earth elements distribution and production capacity, with few studies using quantitative modeling. To achieve reliable results with more factors being taken into consideration, this paper applies the generic multivariant system dynamics model to forecast China’s rare earth elements production trend and Hubbert peak, using Vensim software based on the Hubbert model. The results show that the peak of China’s rare earth elements production will appear by 2040, and that production will slowly decline afterwards. Based on the results, the paper proposes some policy recommendations for the sustainable development of China’s—and the world’s—rare earth elements market and rare earth-related industries.

  7. Rare earth elements as a by-catch of sedimentary deposits. Exploration program of rare earth elements; Selten Erd Elemente als Beifang sedimentaerer Lagerstaetten. Erkundungsprogramm Selten Erd Elemente

    Energy Technology Data Exchange (ETDEWEB)

    Linhardt, E.; Gebhardt, A. (comps.)

    2014-02-15

    The increasing demand for rare earth elements (REE) in the field of ''green technologies'' on the one hand and the shortage of raw materials on the world markets on the other hand confronted also Bavaria as an industrial location with growing supply problems in these ''high tech raw materials''. The aim of exploration was the clarification of the feedstock REE potential of heavy mineral concentrates which are obtained in the industrial extraction and processing of sand and kaolin in existing extraction operations in northern Bavaria as by catch and are potentially winnable or marketable. The in-depth investigation enabled the potential of found rare earth elements and other high-tech metal oxides that can be classified as very likely find it in terms of an economic recovery. [German] Der zunehmende Bedarf an Selten Erd Elementen (SEE) im Bereich der ''Gruenen Technologien'' zum Einen sowie die Rohstoffverknappung auf den Weltmaerkten zum Anderen konfrontiert auch Bayern als Industriestandort mit wachsenden Versorgungsproblemen bei diesen ''high tech-Grundstoffen''. Ziel der Erkundung war die Klaerung des rohstofflichen SEE-Potenzials von Schwermineralkonzentraten, die bei der grosstechnischen Gewinnung und Aufbereitung von Sand und Kaolin in vorhandenen Gewinnungsbetrieben Nordbayerns als Beifang anfallen und potenziell gewinn- bzw. vermarktbar sind. Im Zuge der Untersuchung konnten nutzbare Potenziale von Selten Erd Elementen und anderen high-tech - Metalloxiden gefunden werden, die sehr wahrscheinlich als fuendig im Hinblick auf eine wirtschaftliche Gewinnung eingestuft werden koennen.

  8. Structurally triggered metal-insulator transition in rare-earth nickelates.

    Science.gov (United States)

    Mercy, Alain; Bieder, Jordan; Íñiguez, Jorge; Ghosez, Philippe

    2017-11-22

    Rare-earth nickelates form an intriguing series of correlated perovskite oxides. Apart from LaNiO3, they exhibit on cooling a sharp metal-insulator electronic phase transition, a concurrent structural phase transition, and a magnetic phase transition toward an unusual antiferromagnetic spin order. Appealing for various applications, full exploitation of these compounds is still hampered by the lack of global understanding of the interplay between their electronic, structural, and magnetic properties. Here we show from first-principles calculations that the metal-insulator transition of nickelates arises from the softening of an oxygen-breathing distortion, structurally triggered by oxygen-octahedra rotation motions. The origin of such a rare triggered mechanism is traced back in their electronic and magnetic properties, providing a united picture. We further develop a Landau model accounting for the metal-insulator transition evolution in terms of the rare-earth cations and rationalizing how to tune this transition by acting on oxygen rotation motions.

  9. SEPARATION OF TRANSURANIC ELEMENTS FROM RARE EARTH COMPOUNDS

    Science.gov (United States)

    Kohman, T.P.

    1961-11-21

    A process of separating neptunium and plutonium values from rare earths and alkaline earth fission products present on a solid mixed actinide carrier (Th or U(IV) oxalate or fluoride) --fission product carrier (LaF/sub 3/, CeF/sub 3/, SrF/sub 2/, CaF/sub 2/, YF/sub 3/, La oxalate, cerous oxalate, Sr oxalate, Ca oxalate or Y oxalate) by extraction of the actinides at elevated temperature with a solution of ammonium fluoride and/or ammonium oxalate is described. Separation of the fission-product-containing carriers from the actinide solution formed and precipitation of the neptunium and plutonium from the solution with mineral acid are also accomplished. (AEC)

  10. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Timothy A. DeVol

    2010-03-01

    Full Text Available This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

  11. Rare earth elements in parasol mushroom Macrolepiota procera.

    Science.gov (United States)

    Falandysz, Jerzy; Sapkota, Atindra; Mędyk, Małgorzata; Feng, Xinbin

    2017-04-15

    This study aimed to investigate occurrence and distribution of 16 rare earth elements (REEs) in edible saprobic mushroom Macrolepiota procera, and to estimate possible intake and risk to human consumer. Mushrooms samples were collected from sixteen geographically diverse sites in the northern regions of Poland. The results showed that for Ce as the most abundant among the RREs in edible caps, the mean concentration was at 0.18±0.29mgkg -1 dry biomass. The mean concentration for Σ16 REEs determined in caps of fungus was 0.50mgkg -1 dry biomass and in whole fruiting bodies was 0.75mgkg -1 dry biomass. From a point of view by consumer, the amounts of REEs contained in edible caps of M. procera could be considered small. Hence, eating a tasty caps of this fungus would not result in a health risk for consumer because of exposure to the REEs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Rapidly solidified Mg-Al-Zn-rare earth alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.F.; Das, S.K.; Raybould, D.

    1987-01-01

    Among the light metal alloys, magnesium is the lightest structural material except for beryllium, and yet magnesium alloys have not seen extensive use because of their poor strength and corrosion resistance. Rapid solidification technology offers a possible solution to these problems. A number of Mg-Al-Zn alloys containing rare earth (RE) elements (e.g. Ce, Pr, Y, and Nd) have been investigated using rapid solidification processing for possible structural applications. The processing consists of planar flow or jet casting into ribbons, pulverization of ribbon to powder, and consolidation of powder into bulk shapes. The mechanical properties of some of these alloys show attractive combinations of strength, ductility and corrosion resistance. The microstructures of these alloys are correlated with their mechanical properties. The rapidly solidified Mg-Al-Zn-RE alloys show great potential for applications in automotive and aerospace industries. 7 references.

  13. Luminescent rare-earth-based MOFs as optical sensors.

    Science.gov (United States)

    Mahata, Partha; Mondal, Sudip Kumar; Singha, Debal Kanti; Majee, Prakash

    2017-01-03

    Rare-earth-based metal-organic frameworks (ReMOFs) have emerged as an interesting family of compounds, for which new properties are increasingly being found. Based on the potential of ReMOFs, resulting from their optical properties, large numbers of investigations have been carried out during the last decade. Among these investigations, ReMOFs as optical sensors, using their luminescence properties, are increasingly becoming an attractive and useful topic of research. In this study, we have provided the basics of the luminescence behaviour of ReMOFs, various possible sensing mechanisms, and a summary of the uses of ReMOFs for the sensing of nitro explosives, cations, anions, small molecules, pH, and temperature.

  14. Addressing Criticality in Rare Earth Elements via Permanent Magnets Recycling

    Science.gov (United States)

    Nlebedim, I. C.; King, A. H.

    2018-02-01

    Rare earth elements (REEs) are critical for many advanced technologies and are faced with potential supply disruptions. Recycling of permanent magnets (PMs) can be good sources for REEs which can help minimize global dependence on freshly mined REEs, but PMs are rarely recycled. Recycling of PMs has been discussed with respect to improving REEs resource sustainability. Some challenges to be addressed in order to establish industrially deployable technologies for PMs recycling have also been discussed, including profitability, energy efficiency and environmental impacts. Key considerations for promoting circular economy via PMs recycling is proposed with the focus on deciding the target points in the supply chain at which the recycled products will be inserted. Important technical considerations for recycling different forms of waste PMs, including swarfs, slags, shredded and intact hard disk drives magnets, have been presented. The aspects of circular economy considered include reusing magnets, remanufacturing magnets and recovering of REEs from waste PMs.

  15. Addressing Criticality in Rare Earth Elements via Permanent Magnets Recycling

    Science.gov (United States)

    Nlebedim, I. C.; King, A. H.

    2017-12-01

    Rare earth elements (REEs) are critical for many advanced technologies and are faced with potential supply disruptions. Recycling of permanent magnets (PMs) can be good sources for REEs which can help minimize global dependence on freshly mined REEs, but PMs are rarely recycled. Recycling of PMs has been discussed with respect to improving REEs resource sustainability. Some challenges to be addressed in order to establish industrially deployable technologies for PMs recycling have also been discussed, including profitability, energy efficiency and environmental impacts. Key considerations for promoting circular economy via PMs recycling is proposed with the focus on deciding the target points in the supply chain at which the recycled products will be inserted. Important technical considerations for recycling different forms of waste PMs, including swarfs, slags, shredded and intact hard disk drives magnets, have been presented. The aspects of circular economy considered include reusing magnets, remanufacturing magnets and recovering of REEs from waste PMs.

  16. Gaps and pseudogaps in perovskite rare earth nickelates

    Directory of Open Access Journals (Sweden)

    S. James Allen

    2015-06-01

    Full Text Available We report on tunneling measurements that reveal the evolution of the quasiparticle state density in two rare earth perovskite nickelates, NdNiO3 and LaNiO3, that are close to a bandwidth controlled metal to insulator transition. We measure the opening of a sharp gap of ∼30 meV in NdNiO3 in its insulating ground state. LaNiO3, which remains a correlated metal at all practical temperatures, exhibits a pseudogap of the same order. The results point to both types of gaps arising from a common origin, namely, a quantum critical point associated with the T = 0 K metal-insulator transition. The results support theoretical models of the quantum phase transition in terms of spin and charge instabilities of an itinerant Fermi surface.

  17. Gaps and pseudogaps in perovskite rare earth nickelates

    Energy Technology Data Exchange (ETDEWEB)

    Allen, S. James; Ouellette, Daniel G.; Kally, James; Kozhanov, Alex [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Hauser, Adam J.; Mikheev, Evgeny; Zhang, Jack Y.; Moreno, Nelson E.; Son, Junwoo; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106 (United States); Balents, Leon [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)

    2015-06-01

    We report on tunneling measurements that reveal the evolution of the quasiparticle state density in two rare earth perovskite nickelates, NdNiO{sub 3} and LaNiO{sub 3}, that are close to a bandwidth controlled metal to insulator transition. We measure the opening of a sharp gap of ∼30 meV in NdNiO{sub 3} in its insulating ground state. LaNiO{sub 3}, which remains a correlated metal at all practical temperatures, exhibits a pseudogap of the same order. The results point to both types of gaps arising from a common origin, namely, a quantum critical point associated with the T = 0 K metal-insulator transition. The results support theoretical models of the quantum phase transition in terms of spin and charge instabilities of an itinerant Fermi surface.

  18. Thermodynamic properties of mixed-ligand rare earth pivalates

    Energy Technology Data Exchange (ETDEWEB)

    Dobrokhotova, Zh.V., E-mail: Zhdobro@yandex.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Tyurin, A.V., E-mail: tac@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Fomina, I.G., E-mail: fomina@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Gavrichev, K.S., E-mail: gavrich@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Ryumin, M.A., E-mail: Ryumin80@mail.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Bykov, M.A., E-mail: mich@td.chem.msu.ru [Department of Chemistry, Lomonosov Moscow State University, 1 Leninskie Gory, 119889 Moscow (Russian Federation); Emelina, A.L., E-mail: emelina@td.chem.msu.ru [Department of Chemistry, Lomonosov Moscow State University, 1 Leninskie Gory, 119889 Moscow (Russian Federation); Novotortsev, V.M., E-mail: vmnov@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation); Eremenko, I.L., E-mail: ilerem@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky Prosp., 119991 Moscow (Russian Federation)

    2013-03-20

    Highlights: ► 12 rare earth pivalate complexes were measured by adiabatic calorimetry and DSC. ► Thermodynamic functions in the studied temperature range were calculated. ► No phase transitions for the (phen){sub 2}Ln{sub 2}(piv){sub 6} were found from 5 K to temperature of ligand removal. - Abstract: For structurally characterized dinuclear rare earth pivalate complexes, Ln{sub 2}(piv){sub 6}(Hpiv){sub 6}·Hpiv (Hpiv is pivalic acid, Ln = La (1), Sm (2), Eu (3), and Gd (4)), Tb{sub 2}(piv){sub 6}(Hpiv){sub 6} (5), (bpy){sub 2}Ln{sub 2}(piv){sub 6}, (bpy = 2,2′-bipyridine, Ln = Sm (6), Eu (7), Gd (8), and Er (9)), and (phen){sub 2}Ln{sub 2}(piv){sub 6} (phen = 1,10-phenanthroline, Ln = Sm (10), Eu (11), and Tb (12)), the temperature dependences of the heat capacities were measured by adiabatic and differential scanning calorimetry, and the thermodynamic functions C{sub p}{sup 0}(T), S{sup 0}(T), φ{sup 0}(T), and H{sup 0}(T) − H{sup 0}(0) were calculated. The C{sub p}{sup 0}(T) curves for the complexes with pivalic acid and 2,2′-bipyridine show anomalies, whereas no structural changes are observed for the complexes with 1,10-phenanthroline between the temperature range from 5 K to the temperature of the ligand removal.

  19. Influence of selected rare earth metals on structural characteristics of 42CrMo4 steel

    Directory of Open Access Journals (Sweden)

    J. Drápala

    2016-10-01

    Full Text Available The influence of rare earth metals (REM addition on solidification structure of the low-carbon 42CrMo4 steel was investigated. Alloys were prepared by means of a centrifugal casting. The addition of cerium, praseodymium or mischmetal in the steel produced greatly improved solidification structure with a suppressed columnar grain zone, finer grain size in the equiaxed grain zone. The additions occurred in the steel bath in the form of REM oxide and/or oxide-sulphide inclusions and as dissolved REM segregated along with other elements at prior grain boundaries and interdendritic spaces. Microstructure (light microscope, SEM/EDX chemical microanalysis, and TOF-SIMS analysis – mapping of elements in the structure of alloys were obtained.

  20. Health risk assessment of rare earth elements in cereals from mining area in Shandong, China.

    Science.gov (United States)

    Zhuang, Maoqiang; Wang, Liansen; Wu, Guangjian; Wang, Kebo; Jiang, Xiaofeng; Liu, Taibin; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhang, Junli; Zhou, Jingyang; Zhao, Jinshan; Chu, Zunhua

    2017-08-29

    To investigate the concentrations of rare earth elements in cereals and assess human health risk through cereal consumption, a total of 327 cereal samples were collected from rare earth mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The medians of total rare earth elements in cereals from mining and control areas were 74.22 μg/kg and 47.83 μg/kg, respectively, and the difference was statistically significant (P rare earth elements concentrations (109.39 μg/kg and 77.96 μg/kg for mining and control areas, respectively) and maize had the lowest rare earth elements concentrations (42.88 μg/kg and 30.25 μg/kg for mining and control areas, respectively). The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes of rare earth elements through cereal consumption were considerably lower than the acceptable daily intake (70 μg/kg bw). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to rare earth elements on children.

  1. Applications of Transparent Conducting Oxides in Organic Light Emitting Devices.

    Science.gov (United States)

    Yan, Meng; Zhang, Qiaoxia; Zhao, Yanghua; Yang, Jianping; Yang, Tao; Zhang, Jian; Li, Xing'ao

    2015-09-01

    Organic light emitting devices (OLEDs) have received great attention in the field of flat panel display. The transparent metal oxide semiconductor materials play crucial roles in the applications of OLEDs and have strong influence on the performance of OLEDs. In this review, we mainly pay attention to the application of transparent conducting oxides (TCOs) as anodes and buffer layers in OLEDs. Currently indium tin oxide (ITO) is the most widely used anode material in OLEDs owing to the advantage on electrical and optical properties, such as high work function, low resistivity and high transparency. TCO materials, such as ZnO et al., as the anode candidates also have been discussed and analyzed. The energy level can be controlled by semiconductor doping which improve the carrier density and Hall mobility. Interfacial engineering between the anodes and the overlying organic layers is an important process to obtain the high performance of the devices. Physical, chemical and the combined treatment methods to modify the TCO/organic interfaces are reviewed. The property of anode/organic interfaces can be modified and enhanced by introducing the buffer layers between anodes and hole transport layers.

  2. A Novel Synthesis Routine for Woodwardite and Its Affinity towards Light (La, Ce, Nd) and Heavy (Gd and Y) Rare Earth Elements.

    Science.gov (United States)

    Consani, Sirio; Balić-Žunić, Tonci; Cardinale, Anna Maria; Sgroi, Walter; Giuli, Gabriele; Carbone, Cristina

    2018-01-14

    A synthetic Cu-Al-SO₄ layered double hydroxide (LDH), analogue to the mineral woodwardite [Cu1-xAlx(SO₄)x/2(OH)₂·nH₂O], with x rare earth elements (LREEs) (La, Ce, and Nd) and heavy rare earth elements (HREEs) (Gd and Y) in order to test the affinity of the Cu-Al-SO₄ LDH to the incorporation of REEs. The concentration of rare earth elements (REEs) in the solid fraction was in the range of 3.5-8 wt %. The results showed a good affinity for HREE and Nd, especially for materials synthesised at pH 10.0, whereas the affinities for Ce and La were much lower or non-existent. The thermal decomposition of the REE-doped materials generates a mixture of Cu, Al, and REE oxides, making them interesting as precursors in REE oxide synthesis.

  3. Combinatorial investigation of rare-earth free permanent magnets

    Science.gov (United States)

    Fackler, Sean Wu

    The combinatorial high throughput method allows one to rapidly study a large number of samples with systematically changing parameters. We apply this method to study Fe-Co-V alloys as alternatives to rare-earth permanent magnets. Rare-earth permanent magnets derive their unmatched magnetic properties from the hybridization of Fe and Co with the f-orbitals of rare-earth elements, which have strong spin-orbit coupling. It is predicted that Fe and Co may also have strong hybridization with 4d and 5d refractory transition metals with strong spin-orbit coupling. Refractory transition metals like V also have the desirable property of high temperature stability, which is important for permanent magnet applications in traction motors. In this work, we focus on the role of crystal structure, composition, and secondary phases in the origin of competitive permanent magnetic properties of a particular Fe-Co-V alloy. Fe38Co52V10, compositions are known as Vicalloys. Fe-CoV composition spreads were sputtered onto three-inch silicon wafers and patterned into discrete sample pads forming a combinatorial library. We employed highthroughput screening methods using synchrotron X-rays, wavelength dispersive spectroscopy, and magneto-optical Kerr effect (MOKE) to rapidly screen crystal structure, composition, and magnetic properties, respectively. We found that in-plane magnetic coercive fields of our Vicalloy thin films agree with known bulk values (300 G), but found a remarkable eight times increase of the out-of-plane coercive fields (˜2,500 G). To explain this, we measured the switching fields between in-plane and out-of-plane thin film directions which revealed that the Kondorsky model of 180° domain wall reversal was responsible for Vicalloy's enhanced out-of-plane coercive field and possibly its permanent magnetic properties. The Kondorsky model suggests that domain-wall pinning is the origin of Vicalloy's permanent magnetic properties, in contrast to strain, shape, or

  4. Preparation of volatile rare earth tris-acetylacetonates by heating their hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Martynenko, L.I.; Murav' eva, I.A.; Khalmurzaev, N.K.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1984-06-01

    Heating the rare earth tris-acetylacetonate hydrates in the vacuum atmosphere saturated with vapors of dry acetylacetone brings about sublimation of dehydrated acetllacetonates and, in some cases, their hydrated or hydrolized forms, as evident from the data on chemical and IR-spectroscopy analysis. Under these conditions light rare earths do not form sublimating compounds. The sublimate yield in the rare earth series of the yttrium subgroup, insignificant for dysprosium, increase up to 100% for lutetium and ytterbium.

  5. [Physiological effects of rare earth elements and their application in traditional Chinese medicine].

    Science.gov (United States)

    Zhou, Jie; Guo, Lanping; Xiao, Wenjuan; Geng, Yanling; Wang, Xiao; Shi, Xin'gang; Dan, Staerk

    2012-08-01

    The process in the studies on physiological effects of rare earth elements in plants and their action mechanisms were summarized in the aspects of seed germination, photosynthesis, mineral metabolism and stress resistance. And the applications of rare earth elements in traditional Chinese medicine (TCM) in recent years were also overviewed, which will provide reference for further development and application of rare earth elements in TCM.

  6. Promising wastewater treatment using rare earth-doped nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.A., E-mail: moala47@hotmail.com [Materials Science Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Bishay, Samiha T.; Khafagy, Rasha M. [Physics Department, Girls College for Arts, Science and Education, Ain Shams University, Cairo (Egypt); Saleh, N.M. [Physics Department, Faculty of Science, Western Mountain University (Libya)

    2014-01-15

    Single-phases of the spinel nanoferrites Zn{sub 0.5}Co{sub 0.5}Al{sub 0.5}R{sub 0.04}Fe{sub 1.46}O{sub 4}; R=Sm, Pr, Ce and La, were synthesized using the flash auto combustion method. X-ray diffraction (XRD) results indicated that doping nanoferrites with small concentrations of rare earth elements (RE) allowed their entrance to the spinel lattice. Transmission electron microscope (TEM) images revealed that doping with different RE elements resulted in the formation of different nanometric shapes such as nanospheres and nanowires. Doping with Sm{sup 3+} and Ce{sup 3+} resulted in the formation of nanospheres with average diameter of 14 and 30 nm respectively. In addition to the granular nanospheres, doping with Pr{sup 3+} and La{sup 3+} resulted in the formation of some nanowires with different aspect ratios (average length of ≈100 nm and diameter of ≈9 nm) and (average length of ≈150 nm and outer diameter of ≈22 nm) respectively. At fixed temperature, the Ac conductivity (σ) increased as the RE ionic radius increases except for Ce, due to the role of valance fluctuation from Ce{sup 3+} to Ce{sup 4+} ions. La- and Pr-doped nanoferrites showed the highest ac conductivity values, which is most probably due to the presence of large numbers of nanowires in these two types of ferrites. For all entire samples, the effective magnetic moment (μ{sub eff}) decreased, while the Curie temperature (T{sub C}) increased as the RE ionic radius increases. The synthesized rare earth nanoferrites showed promising results in purifying colored wastewater. La-doped ferrite was capable for up-taking 92% of the dye content, followed by Pr-doped ferrite, which adsorbed 85% of the dye, while Sm- and Ce-doped ferrites showed lower dye removal efficiency of 80% and 72% respectively. High dye uptake shown by La- and Pr-doped ferrites is most probably due to the presence of nanowires and their higher Ac conductivity values. These excellent results were not previously reported

  7. Diagenetic uptake of rare earth elements by conodont apatite

    Science.gov (United States)

    Zhang, L.; Algeo, T. J.; Cao, L.; Zhao, L.; Chen, Z. Q.; Li, Z.

    2015-12-01

    The rare earth element (REE) composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction, based on the assumption of preservation of a hydrogenous (seawater-derived) REE signal. Recent work, however, has begun to question the provenance of REEs in conodonts, emphasizing the importance of REEs released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment. Here, we investigate patterns of REE and trace-element abundance in conodonts and their host sediments from the Early to Late Ordovician Huanghuachang and Chenjiahe sections of Hubei Province, South China. Several lines of evidence indicate that REEs in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis: (1) REEs in conodonts show a strong positive correlation to Th and other lithogenic elements; (2) conodonts and whole-rock samples show general patterns of REE and trace-element enrichment that are highly similar to each other and bear no resemblance to seawater elemental concentrations; (3) similar patterns are observed in Triassic conodonts and whole-rock samples; and (4) Y/Ho ratios in conodonts are mostly 90% of REEs from lithogenous sources. Conodonts show pronounced middle rare earth element (MREE) enrichment, a pattern that is unambiguously of diagenetic origin owing to its association with lower Y/Ho ratios. With increasing MREE enrichment of conodont samples, U concentrations and LaN/YbN ratios shift from high to low, and Mn concentrations from low to high. These patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions (i.e., in the zone of Mn(IV) and Fe(III) reduction) but continued at greater burial depths, with most acquisition of secondary REEs at later diagenetic stages. Our findings indicate that (1) conodont apatite frequently does not preserve a recognizable

  8. Monolithically integrated active waveguides and lasers using rare-earth doped spin-on glass

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Sullivan, C.T.; Vawter, G.A. [and others

    1996-09-01

    This LDRD program No. 3505.230 explored a new approach to monolithic integration of active waveguides and rare-earth solid state lasers directly onto III-V substrates. It involved selectively incorporating rare-earth ions into spin-on glasses (SOGs) that could be solvent cast and then patterned with conventional microelectronic processing. The patterned, rare-earth spin-on glasses (RESOGs) were to be photopumped by laser diodes prefabricated on the wafer and would serve as directly integrated active waveguides and/or rare-earth solid state lasers.

  9. Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands.

    Science.gov (United States)

    Li, Tianshu; Kaercher, Sabrina; Roesky, Peter W

    2014-01-07

    A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2(-)) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR(2-)) and P(3-) ligands; and (3) the pure inorganic polyphosphide ligands (Pn(x-)), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides.

  10. Crystallization studies on rare-earth co-doped fluorozirconate-based glasses.

    Science.gov (United States)

    Paßlick, C; Johnson, J A; Schweizer, S

    2013-07-01

    This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In a first step, only europium in its divalent and trivalent oxidation states, Eu(2+) and Eu(3+), is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu(2+) increase the activation energy of the phase transition to an orthorhombic crystal structure. In a second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu(2+) and trivalent Gd(3+), Nd(3+), Yb(3+), or Tb(3+), due to the different atomic radii and electro-negativity of the co-dopants.

  11. Three-color integration on rare-earth-doped GaN electroluminescent thin films

    Science.gov (United States)

    Wang, Y. Q.; Steckl, A. J.

    2003-01-01

    We have realized full color integration on rare-earth-doped thin-film electroluminescent (EL) GaN using lateral integration. Tm, Er, and Eu dopants were in situ doped into GaN thin films during growth in order to obtain blue, green, and red emission, respectively. Three color pixel arrays have been fabricated using spin-on-glass films as the sacrificial layers for lift-off lithography. The pixel dimensions are 0.2×0.7 mm2, and the separation is 0.2 mm. dc EL devices were fabricated using indium tin oxide transparent electrodes. Typical applied voltage was 30-40 V. The blue emission from Tm-doped GaN has a peak at 477 nm, the green emission from Er-doped GaN has two peaks at 537 and 558 nm, while the red emission from Eu-doped GaN has a peak at 621 nm.

  12. Preparation and properties of rare earth element complexes with pyridine-2,6-dicarboxylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Brzyska, Wanda; Ozga, Wanda (Department of Inorganic and General Chemistry, Marie Curie Skodowska University, Lublin (Poland))

    1994-12-12

    The conditions of the formation of rare earth element (Y, La-Lu) dipicolinates were studied, and their quantitative compositions and solubilities in water at 293 K were determined (10[sup -2] to 10[sup -3] mol dm[sup -3]). The IR spectra of the hydrated complexes were recorded and their thermal decomposition in air was determined. During heating the hydrated dipicolinates Ln[sub 2](C[sub 7]H[sub 3]NO[sub 4])[sub 3][center dot]nH[sub 2]O (n=9-25) lose some or all of their water molecules of crystallization water in one, two or three steps; then the anhydrous or hydrated complexes decompose either directly to the oxides (Y, Ce, Sm-Dy, Tm-Lu) or with intermediate formation of oxocarbonates Ln[sub 2]O[sub 2]CO[sub 3] (La, Pr, Nd, Ho, Er).

  13. Normalized rare earth elements in water, sediments, and wine: identifying sources and environmental redox conditions

    Science.gov (United States)

    Piper, David Z.; Bau, Michael

    2013-01-01

    The concentrations of the rare earth elements (REE) in surface waters and sediments, when normalized on an element-by-element basis to one of several rock standards and plotted versus atomic number, yield curves that reveal their partitioning between different sediment fractions and the sources of those fractions, for example, between terrestrial-derived lithogenous debris and seawater-derived biogenous detritus and hydrogenous metal oxides. The REE of ancient sediments support their partitioning into these same fractions and further contribute to the identification of the redox geochemistry of the sea water in which the sediments accumulated. The normalized curves of the REE that have been examined in several South American wine varietals can be interpreted to reflect the lithology of the bedrock on which the vines may have been grown, suggesting limited fractionation during soil development.

  14. Determination of rare earths and thorium in apatites by thermal and epithermal neutron-activation analysis.

    Science.gov (United States)

    Brunfelt, A O; Roelandts, I

    1974-06-01

    A procedure is described for the non-destructive determination of Na, Mn, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu and Th in apatites by thermal and epithermal neutron-activation of independent portions of the material. The method was applied to three apatites with different contents. The precision obtained was better than +/-5% for La, Ce, Sm, Eu, Gd, Tb and Dy and +/-20% for Yb, Nd, Ho, Er and Lu for an apatite with a total rare-earth oxide content of the order of 1%. Determination of Ce, Tb and Yb could only be carried out with thermal neutron-activation analysis, while Gd, Ho and Er could only be determined after irradiation with epithermal neutrons.

  15. Thermodynamic Investigation of the Reduction-Distillation Process for Rare Earth Metals Production

    Science.gov (United States)

    Judge, W. D.; Azimi, G.

    2017-10-01

    Owing to their high vapor pressure, the four rare earth metals samarium, europium, thulium, and ytterbium are produced by reduction-distillation whereby their oxides are reduced with metallic lanthanum in vacuo, and the produced metal is subsequently vaporized off. Here, we performed a thorough thermodynamic investigation to establish a fundamental understanding of the reduction-distillation process. Thermodynamic functions including vapor pressures, Gibbs free energies, and enthalpies of reaction were calculated and compared with available experimental data. Furthermore, the kinetics of the process was explored and theoretical evaporation rates were calculated from thermodynamic data. The thermodynamic model developed in this work can help optimize processing conditions to maximize the yield and improve the overall process.

  16. Magnetic dipole electroexcitations in rare-earth nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Faessler, A.; Nojarov, R.; Scholtz, F.G. (Tuebingen Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)

    1990-08-27

    The M1 excitation of K{sup {pi}}=1{sup +} states through inelastic electron scattering is studied in rare-earth nuclei within a quasiparticle RPA approach with quadrupole-quadrupole, spin-spin and spin-quadrupole residual interactions. The spurious state is removed exactly by a procedure which restores the rotational invariance of the RPA hamiltonian and leads to almost purely isovector vibrations. The DWBA (e, e') form factors and the strongly orbital low-energy M1 spectrum are in a good agreement with the rich experimental data. The purely collective scissor state has largest overlaps with the orbital low-energy RPA excitations but a single overlap does not exceed 15%. Nevertheless, a number of low-lying 1{sup +} states, including the strongest experimentally observed M1 state, can be interpreted as isovector rotational vibrations due to their large overlaps with proposed phonon rotational states, in which only several quasiparticle pairs perform a scissor-type vibrational motion. (orig.).

  17. Light rare earth element depletion during Deepwater Horizon blowout methanotrophy.

    Science.gov (United States)

    Shiller, A M; Chan, E W; Joung, D J; Redmond, M C; Kessler, J D

    2017-09-04

    Rare earth elements have generally not been thought to have a biological role. However, recent work has demonstrated that the light REEs (LREEs: La, Ce, Pr, and Nd) are essential for at least some methanotrophs, being co-factors in the XoxF type of methanol dehydrogenase (MDH). We show here that dissolved LREEs were significantly removed in a submerged plume of methane-rich water during the Deepwater Horizon (DWH) well blowout. Furthermore, incubation experiments conducted with naturally methane-enriched waters from hydrocarbon seeps in the vicinity of the DWH wellhead also showed LREE removal concurrent with methane consumption. Metagenomic sequencing of incubation samples revealed that LREE-containing MDHs were present. Our field and laboratory observations provide further insight into the biochemical pathways of methanotrophy during the DWH blowout. Additionally, our results are the first observations of direct biological alteration of REE distributions in oceanic systems. In view of the ubiquity of LREE-containing MDHs in oceanic systems, our results suggest that biological uptake of LREEs is an overlooked aspect of the oceanic geochemistry of this group of elements previously thought to be biologically inactive and an unresolved factor in the flux of methane, a potent greenhouse gas, from the ocean.

  18. Continental shelves as potential resource of rare earth elements.

    Science.gov (United States)

    Pourret, Olivier; Tuduri, Johann

    2017-07-19

    The results of this study allow the reassessment of the rare earth elements (REE) external cycle. Indeed, the river input to the oceans has relatively flat REE patterns without cerium (Ce) anomalies, whereas oceanic REE patterns exhibit strong negative Ce anomalies and heavy REE enrichment. Indeed, the processes at the origin of seawater REE patterns are commonly thought to occur within the ocean masses themselves. However, the results from the present study illustrate that seawater-like REE patterns already occur in the truly dissolved pool of river input. This leads us to favor a partial or complete removal of the colloidal REE pool during estuarine mixing by coagulation, as previously shown for dissolved humic acids and iron. In this latter case, REE fractionation occurs because colloidal and truly dissolved pools have different REE patterns. Thus, the REE patterns of seawater could be the combination of both intra-oceanic and riverine processes. In this study, we show that the Atlantic continental shelves could be considered potential REE traps, suggesting further that shelf sediments could potentially become a resource for REE, similar to metalliferous deep sea sediments.

  19. Effects of Simulated Rare Earth Recycling Wastewaters on Biological Nitrification.

    Science.gov (United States)

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; Lencka, Malgorzata M; Anderko, Andrzej; Riman, Richard E; Navrotsky, Alexandra

    2015-08-18

    Increasing rare earth element (REE) supplies by recycling and expanded ore processing will result in generation of new wastewaters. In some cases, disposal to a sewage treatment plant may be favored, but plant performance must be maintained. To assess the potential effects of such wastewaters on biological treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50, and 100 ppm), and the extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions at 50 and 100 ppm inhibited N. europaea, even when virtually all of the REE was insoluble. Provision of TBP with Eu increased N. europaea inhibition, although TBP alone did not substantially alter activity. For N. winogradskyi cultures, Eu or Y additions at all tested levels induced significant inhibition, and nitrification shut down completely with TBP addition. REE solubility was calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, typically controlled by the precipitation of REE hydroxides but also likely affected by the formation of unknown phosphate phases, which determined aqueous concentrations experienced by the microorganisms.

  20. Syntheses and structures of new rare-earth metal tetracyanidoborates

    Energy Technology Data Exchange (ETDEWEB)

    Falk, Fanni; Hackbarth, Liisa; Koeckerling, Martin [Anorganische Festkoerperchemie, Institut fuer Chemie, Universitaet Rostock, Albert-Einstein-Str. 3a, 18059, Rostock (Germany); Herkert, Lorena; Mueller-Buschbaum, Klaus; Finze, Maik [Institut fuer Anorganische Chemie, Institut fuer nachhaltige Chemie and Katalyse mit Bor (ICB), Julius-Maximilians-Universitaet Wuerzburg, Am Hubland, 97074, Wuerzburg (Germany)

    2017-05-04

    Six new rare-earth metal tetracyanidoborates were prepared and characterized by single-crystal X-ray diffraction. Crystals of these salts contain co-crystallized solvent molecules, such as water, acetone, ethanol, or diethyl ether. In [La(EtOH){sub 3}(H{sub 2}O){sub 2}{B(CN)_4}{sub 3}] (1), [La(EtOH)(H{sub 2}O){sub 4}{B(CN)_4}{sub 3}].Et{sub 2}O (2), and [Y(EtOH)(H{sub 2}O){sub 4}{B(CN)_4}{sub 3}].EtOH (6) the tetracyanidoborate anions are all or in part bonded to the RE{sup 3+} ions, whereas in [Pr(H{sub 2}O){sub 9}][B(CN){sub 4}]{sub 3}.(CH{sub 3}){sub 2}CO (3), [Er(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.(CH{sub 3}){sub 2}CO (4), and [Lu(EtOH)(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3}.EtOH.0.5H{sub 2}O (5) the [B(CN){sub 4}]{sup -} anions are not coordinated to the central metal atoms. Only in 1, one of the three crystallographically independent [B(CN){sub 4}]{sup -} anions acts as a bridging ligand. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Mechanical and thermophysical properties of rare-earth monopnictides

    Science.gov (United States)

    Bhalla, Vyoma; Singh, Devraj; Jain, Sushil Kumar

    2016-08-01

    The present paper addresses the temperature dependent elastic, mechanical and thermal properties of NaCl structure (B1 type) holmium monopnictides, HoX (X = N, P, As, Sb, Bi) computed using Coulomb and Born repulsive potentials extended up to second nearest neighbors. The second-order elastic constants (SOECs) of single crystals HoX are calculated as a function of temperature in the range 0-500K. The compounds under study are found to be brittle in nature. Beside these calculations, the theoretical hardness has been obtained for various rare-earth monopnictides using the elastic properties in the polycrystalline approach. The obtained hardness values indicate HoN to be hard, but cannot be considered super hard. The anisotropic nature of the chosen single crystal is an important physical quantity in studying the directional dependent thermal properties such as Debye temperature and thermal conductivity computed using ultrasonic velocities along different crystallographic directions. The obtained results are discussed in correlation with mechanical and thermophysical properties of similar materials.

  2. Raman scattering study of rare-earth hexaboride

    Science.gov (United States)

    Ogita, N.; Nagai, S.; Udagawa, M.; Iga, F.; Sera, M.; Oguchi, T.; Akimitsu, J.; Kunii, S.

    2005-04-01

    The excitation-energy, polarization, pressure, and temperature dependences of Raman scattering spectra have been measured for the RB6 crystals ( R=Ca, La, Ce, Pr, Sm, Gd, Dy, and Yb). In the Raman spectra, the extra peaks have been clearly observed at around 200 cm-1, except for the Raman-active phonons and CEF excitations. The extra peaks show anomalous behavior in the temperature, polarization, and lattice parameter dependences. These anomalous behaviors originate from the vibration of the rare-earth ions in octahedral B 6 cage, and the extra peaks can be assigned as the second-order Raman excitations of T 1u[3]. To check the validity of our assignment, we have measured the pressure dependence. In this paper, the results of the “ extra peaks” at about 200 cm -1, and pressure dependence of SmB 6 are presented. The sample preparation and experimental details are explained in our previous report [3]. The Pm3m symmetry of RB 6 gives us the phonon numbers at Brilloiun zone center; Γ=A1g+Eg+T1g+T2g+3T1u+T2u. The Raman-active phonons are A1g, Eg, and T2g, which are the vibration of boron octahedra. In cubic symmetry, all Raman-active phonons appear in the (x+y,x+y) polarization geometry. In the notation of (x,y), x and y denote the polarization directions of incident and scattered light, respectively. x and y correspond to the crystal axes of [1 0 0] and [0 1 0], respectively. Fig. 1 shows the Raman spectra of trivalent RB6 at room temperature in the energy region below T2g phonons ( ≃700 cm-1). Each spectrum is depicted in the order of the decreasing lattice parameters from top to bottom. As shown in Fig. 1, the energy of T2g phonon decreases with increasing lattice parameter, and this is normal dependence. However, the extra peaks (arrows) show an anti-trend for T2g phonon's. Focusing on the size of cage space consisting of surrounding borons for rare earth ion a-rR( a and rR are lattice parameter and ionic radius, respectively), the energy of the peaks is

  3. Size distribution of rare earth elements in coal ash

    Science.gov (United States)

    Scott, Clinton T.; Deonarine, Amrika; Kolker, Allan; Adams, Monique; Holland, James F.

    2015-01-01

    Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is variably enriched in REEs relative to feed coal (e.g, Seredin and Dai, 2012) and that enrichment increases with decreasing size fractions (Blissett et al., 2014). In order to further explore the REE resource potential of coal ash, and determine the partitioning behavior of REE as a function of grain size, we studied whole coal and fly ash size-fractions collected from three U.S commercial-scale coal-fired generating stations burning Appalachian or Powder River Basin coal. Whole fly ash was separated into , 5 um, to 5 to 10 um and 10 to 100 um particle size fractions by mechanical shaking using trace-metal clean procedures. In these samples REE enrichments in whole fly ash ranges 5.6 to 18.5 times that of feedcoals. Partitioning results for size separates relative to whole coal and whole fly ash will also be reported. 

  4. Rare Earth elements in individual minerals in Shergottites

    Science.gov (United States)

    Wadhwa, Meenakshi; Crozaz, Ghislaine

    1993-01-01

    Shergottites (i.e., Shergotty, Zagami, EETA79001, ALHA77005, and LEW88516) are an important set of achondrites because they comprise the majority of the SNC group of meteorites (nine, in total, known to us), which are likely to be samples of the planet Mars. Study of these meteorites may therefore provide valuable information about petrogenetic processes on a large planetary body other than Earth. Rare earth element (REE) distributions between various mineral phases were found to be useful in geochemically modeling the petrogenesis of various rock types (terrestrial and meteoritic). However, with the exception of a few ion microprobe studies and analyses of mineral separates, there has previously not been any comprehensive effort to characterize and directly compare REE in individual minerals in each of the five known shergottites. Ion microprobe analyses were made on thin sections of each of the shergottites. Minerals analyzed were pyroxenes (pigeonite and augite), maskelynite, and whitlockite. The REE concentrations in each mineral type in each shergottite is given.

  5. Mechanisms affecting emission in rare-earth-activated phosphors

    Energy Technology Data Exchange (ETDEWEB)

    TALLANT,DAVID R.; SEAGER,CARLETON H.; SIMPSON,REGINA L.

    2000-05-23

    The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission.

  6. Separation characteristics of rare earth elements in the TOPO/DTPA - Salting-out reagent solution system

    Energy Technology Data Exchange (ETDEWEB)

    Miyahara, S.; Koma, Yoshikazu; Koyama, Tomozo; Tanaka, Yasumasa [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works; Kano, J.

    1998-11-01

    A test of mutual separation of rare earth elements was carried out using an organic phosphorus extraction solvent TOPO (tri-octyl phosphorus oxide). It was found that the distribution ratio monotonously increased with the atomic number and the separation factor of La/Ln was 10{sup 3}. Under the condition that a sufficient quantity of DTPA compared with the amount of rare earth metals and pH > 1.5 in which DTPA easily formed complexes with lanthanides, the following conclusions were obtained; (i) the separation factor was not affected by pH, the kind of salting-out reagent, or the concentration, (ii) the extraction reaction with TOPO and complex formation with DTPA mainly contributed to the separation of lanthanides, and (iii) the separation factor computed by means of the distribution ratio of TOPO extraction and complex formation constant for DTPA more or less agreed with the empirical value. Separation of rare earth elements using TOPO revealed similar characteristics to those of systems with CMPO and TBP. (H. Baba)

  7. Photocapacitance measurements on MOS light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Michael; Buerger, Danilo; Rebohle, Lars; Skorupa, Wolfgang; Helm, Manfred; Schmidt, Heidemarie [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, Dresden (Germany)

    2009-07-01

    The photocapacitance (PC) has been probed on MOS diodes with an Eu-implanted SiO{sub 2} layer. In general, rare earth implanted SiO{sub 2} layers in MOS diodes are of great interest for possible applications in integrated metal-oxide-semiconductor light emitting devices (MOSLEDs). For example, green and ultraviolet electroluminescence has been probed on SiO{sub 2}:Tb-MOSLEDs and SiO{sub 2}:Gd-MOSLEDs, respectively. MOSLEDs reach external quantum efficiencies between 1% and 16%, and the electroluminescence peaks are typically ascribed to 4f-intrashell transitions of trivalent rare earth ions. A clear capacitance change has been observed for different wavelengths under monochromatic illumination. Some of the detected peaks correspond to the energies of 4f-intrashell transitions of the Eu ions. According to this, the number of active luminescence centers in MOSLEDs may be determined from PC measurements. Some 4f-intrashell transitions have been also observed by means of electroluminescence measurements on the same MOSLEDs. To emphasize the physical significance of the PC data recorded on SiO{sub 2}:Eu-MOSLEDs, we also compare PC data recorded on different MOSLEDs implanted with other rare earth ions.

  8. The Influence of Strain Path on Rare Earth Recrystallization Textures in a Magnesium-Zinc-Rare Earth Alloy

    Science.gov (United States)

    Griffiths, D.; Davis, B.; Robson, J. D.

    2018-01-01

    In this study, the effect of strain path on texture evolution during cold rolled and annealing of hot rolled Mg-Zn-Rare-Earth (RE) alloy (ZEK100) sheet has been investigated. Strain path during cold rolling has been varied by changing rolling direction with respect to the original hot rolling (HR) direction of the sheet. Cold rolling either parallel or perpendicular to the HR direction leads to spread and split of basal poles in the transverse direction (TD) during annealing, characteristic of Mg-Zn-RE alloys. However, when the sheet is continuously rotated between cold rolling passes, this texture spread is not produced. It is demonstrated that a change in dislocation activity, as predicted by crystal plasticity modeling, cannot explain the unusual textures developed in Mg-Zn-RE alloys. Instead, the role of strain path in determining shear band evolution is considered to be critical. When shear bands are suppressed by continuously rotating the specimen, the distinct Zn-RE texture is not produced. Furthermore, it is demonstrated the dominance of the TD spread grains emerges gradually during recrystallization, leading to the final observed texture.

  9. Nano- and micro-sized rare-earth carbonates and their use as precursors and sacrificial templates for the synthesis of new innovative materials.

    Science.gov (United States)

    Kaczmarek, Anna M; Van Hecke, Kristof; Van Deun, Rik

    2015-04-21

    This review focuses on rare-earth carbonate materials of nano- and micro-size. It discusses in depth the different types of rare-earth carbonate compounds, diverse synthetic approaches and possibilities for chemical tuning of the size, shape and morphology. The interesting luminescence properties of lanthanide doped rare-earth carbonates and their potential applications for example as efficient white light sources and biolabels are reviewed. Additionally the use of these materials as precursors for the synthesis of nano-/micro-sized oxides, and their application as sacrificial templates for morphology-controlled synthesis of other materials such as YVO4, LaF3, NaYF4 and others is overviewed.

  10. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    Science.gov (United States)

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  11. Automated Quantitative Rare Earth Elements Mineralogy by Scanning Electron Microscopy

    Science.gov (United States)

    Sindern, Sven; Meyer, F. Michael

    2016-09-01

    Increasing industrial demand of rare earth elements (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE element deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become

  12. Rare-earth elements in human colostrum milk.

    Science.gov (United States)

    Poniedziałek, Barbara; Rzymski, Paweł; Pięt, Małgorzata; Niedzielski, Przemysław; Mleczek, Mirosław; Wilczak, Maciej; Rzymski, Piotr

    2017-11-01

    Rare-earth elements (REEs) are used in a growing number of applications, and their release to environment has increased over the decades. Knowledge of REEs in human milk and factors that could possibly influence their concentration is scarce. This study evaluated the concentrations of 16 REEs (Ce, Eu, Er, Gd, La, Nd, Pr, Sc, Sm, Dy, Ho, Lu, Tb, Tm, Y, and Yb) in human colostrum milk collected from Polish women (n = 100) with the ICP-OES technique. The concentrations (mean ± SD) of Pr (41.9 ± 13.2 μg L -1 ), Nd (11.0 ± 4.0 μg L -1 ), La (7.1 ± 5.2 μg L -1 ), and Er (2.2 ± 0.8 μg L -1 ) were found above detection limits. The total mean ± SD concentration of detected REEs was 60.9 ± 17.8 μg L -1 . Current smokers displayed significantly increased Nd concentrations compared to women who had never smoked. No other associations between REEs in colostrum milk and age, diet in pregnancy (food supplement use and frequency of fish, meat, and vegetable consumption) or place of living (urban/rural) were found. This study adds to general understanding of the occurrence and turnover of REEs in women and human fluids.

  13. Rare Earth Element Partitioning in Lunar Minerals: An Experimental Study

    Science.gov (United States)

    McIntosh, E. C.; Rapp, J. F.; Draper, D. S.

    2016-01-01

    The partitioning behavior of rare earth elements (REE) between minerals and melts is widely used to interpret the petrogenesis and geologic context of terrestrial and extra-terrestrial samples. REE are important tools for modelling the evolution of the lunar interior. The ubiquitous negative Eu anomaly in lunar basalts is one of the main lines of evidence to support the lunar magma ocean (LMO) hypothesis, by which the plagioclase-rich lunar highlands were formed as a flotation crust during differentiation of a global-scale magma ocean. The separation of plagioclase from the mafic cumulates is thought to be the source of the Eu depletion, as Eu is very compatible in plagioclase. Lunar basalts and volcanic glasses are commonly depleted in light REEs (LREE), and more enriched in heavy REEs (HREE). However, there is very little experimental data available on REE partitioning between lunar minerals and melts. In order to interpret the source of these distinctive REE patterns, and to model lunar petrogenetic processes, REE partition coefficients (D) between lunar minerals and melts are needed at conditions relevant to lunar processes. New data on D(sub REE) for plagioclase, and pyroxenes are now available, but there is limited available data for olivine/melt D(sub REE), particularly at pressures higher than 1 bar, and in Fe-rich and reduced compositions - all conditions relevant to the lunar mantle. Based on terrestrial data, REE are highly incompatible in olivine (i.e. D much less than 1), however olivine is the predominant mineral in the lunar interior, so it is important to understand whether it is capable of storing even small amounts of REE, and how the REEs might be fractionatied, in order to understand the trace element budget of the lunar interior. This abstract presents results from high-pressure and temperature experiments investigating REE partitioning between olivine and melt in a composition relevant to lunar magmatism.

  14. R. f. -sputtered luminescent rare earth and yttrium oxysulphide films

    Energy Technology Data Exchange (ETDEWEB)

    Sella, C.; Martin, J.C.; Charreire, Y.

    1982-04-16

    The rare earth and yttrium oxysulphides form a family of highly luminescent materials and are of practical importance for cathode ray tubes and other visual display devices. The conventional screens are composed of a phosphor powder and have limited brightness, resolution and contrast. The brightness is limited by heating of the phosphor and poor thermal conductivity between the particles and the substrate. The resolution is limited by the particle size. The contrast is reduced by a high diffuse reflectivity of ambient light. Continuous thin films are not subject to these limitations. In previous attempts to produce such films by classical evaporation or sputtering techniques most of the luminous efficiency of the material was lost. When r.f. sputtering was carried out in standard vacuum equipment (10/sup -6/ Torr), a sulphur deficiency in the films was observed owing to the residual oxygen pressure. To overcome these difficulties, we used a new sputtering system designed for high purity deposition and mounted in an ultrahigh vacuum unit. Two methods were used to prepare Y/sub 2/O/sub 2/S and La/sub 2/O/sub 2/S luminescent films activated by Eu/sup 3 +/ (red) and by Tb/sup 3 +/ (green): (1) deposition from a pure oxysulphide target with subsequent treatment in H/sub 2/S between 700 and 850/sup 0/C; (2) deposition from a mixed sulphide-oxysulphide target with subsequent treatment in argon or an Ar-H/sub 2/ mixture between 500 and 850/sup 0/C. All films were investigated by X-ray diffraction, scanning and transmission electron microscopies, cathodoluminescence and photoluminescence excited with a pulsed laser.

  15. Rare earth element mobility in the Roffna Gneiss, Switzerland

    Science.gov (United States)

    Vocke, Robert D.; Hanson, Gilbert N.; Grünenfelder, Marc

    1987-02-01

    The Roffna Gneiss, a deformed Hercynian granite porphyry within the Penninic nappes of eastern Switzerland, underwent extreme cataclasis with the progressive development of phengite towards the margins of the nappe under conditions of the glaucophane schist to greenschist facies. This resulted in the selective mobilization of major and trace elements over distances of 10's to 100's of meters and the resetting of the Rb — Sr whole rock isotopic systems some 100 my ago. The component ratios and compositionvolume relationships of progressively deformed gneiss samples studied here suggest that this process was essentially isovolumetric. The mineralogy of the deformation sequence appears to have been controlled by a reaction involving the breakdown of microcline, albite and biotite and the formation of phengite and quartz. The fluids introduced Mg and H2O, promoting the development of phengite, and removed the Na being released by the breakdown of albite. The fluids were most probably derived from the surrounding Triassic carbonates and quartzites. These relatively high fO2 and carbonate rich fluids also introduced rare earth elements (REE) into the gneiss. The gneiss was progressively enriched in Eu up to 60%, Y up to 40%, and Yb up to 100%. These enrichments are associated with the development of epitaxial xenotime around zircon in the most phengite-rich sample. While the REE were mobile, uranium and thorium were essentially immobile. The formation of xenotime was suggested to explain the observed heavy REE enrichment when large differences in the REE contents were found for replicate analyses using HF and then lithium metaborate for dissolution. These differences arose because xenotime, like monazite, can be difficult (if not impossible) to dissolve in hydrofluoric acid. Due to the possibility of incomplete sample dissolution, we now recommend fusion with lithium metaborate for all REE, Lu — Hf or Sm — Nd studies.

  16. Giant optical gain in rare-earth-ion-doped thin films and waveguides

    NARCIS (Netherlands)

    Geskus, D.; Aravazhi, S.; García Blanco, Sonia Maria; Pollnau, Markus

    In a rare-earth-ion-doped double tungstate channel waveguide amplifier, we demonstrate an ultra-high modal gain of 950 dB/cm, two order of magnitude higher than in other rare-earth-ion-doped materials and comparable to modal gain in semiconductors.

  17. Multiplet effects in the electronic structure of light rare-earth metals

    NARCIS (Netherlands)

    Lebegue, S.; Svane, A.; Katsnelson, M.I.; Lichtenstein, A.I.; Eriksson, O.

    2006-01-01

    The excited-state properties of the light rare-earth elemental metals praseodymium, neodymium, and samarium are studied within the Hubbard-I formalism. This method describes the multiplets of the rare-earth f shell by an exact diagonalization of the two-body part of the Hamiltonian. Subsequently,

  18. Study of rare earth local moment magnetism and strongly correlated phenomena in various crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Tai [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Benefiting from unique properties of 4f electrons, rare earth based compounds are known for offering a versatile playground for condensed matter physics research as well as industrial applications. This thesis focuses on three specific examples that further explore the rare earth local moment magnetism and strongly correlated phenomena in various crystal structures.

  19. Countering China’s Dominance in the Rare Earth Element Market System

    Science.gov (United States)

    2012-02-02

    scientists and inventors with the support that they need.‖55 16 Developing trade partnerships between other reliable trading partners and allies...www.usmagneticmaterials.com/documents/RARE-EARTHS-IN-US-DEFENSE- APPS - Hendrick.pdf. (accessed October 19, 2011). 12 REE - Rare Earth Elements and their Uses

  20. DFT Calculations using WIEN2K to determine oxygen defect structure of rare earth doped ceria

    CERN Document Server

    Khalife, Ali Rida

    2014-01-01

    We perform density functional calculations using the program WIEN2K in order to study oxygen vacancies in rare earth doped ceria. The calculation for all rare earth elements were prepared, however only those foe Cadmium and Europium were performed due to lack of time. Also a short description of my stay at CERN was presented

  1. Environmental Defects And Economic Impact On Global Market Of Rare Earth Metals

    Science.gov (United States)

    Charalampides, G.; Vatalis, K.; Karayannis, V.; Baklavaridis, A.

    2016-11-01

    Rare earth elements include the 14 lanthanides as well as lanthanium and often yttrium. Actually, most of them are not very rare and occur widely dispersed in a variety of rocks. Rare earth metals are vital to some of the world's faster growing industries: catalysts, Nd-magnets, ceramics, glass, metallurgy, battery alloys, electronics and phosphors. Worldwide, the main countries for distribution of rare earths deposits include China, USA, Russia, Brasil, India, Australia, Greenland and Malaysia. The mining and processing of rare earth metals usually result in significant environmental defects. Many deposits are associated with high concentrations of radioactive elements such as uranium and thorium, which requires separate treatment and disposal. The accumulation of rare earth elements in soils has occurred due to pollution caused by the exploitation of rare earth resources and the wide use of rare earths as fertilizers in agriculture. This accumulation has a toxic effect on the soil microfauna community. However, there are large differences in market prices due to the degree of purity determined by the specifications in the applications. The main focus of this article is to overview Rare Earth Metals’ overall impact on global economy and their environmental defects on soils during processing techniques and as they are used as fertilizers.

  2. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Science.gov (United States)

    2010-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare...

  3. Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by inductively coupled plasma-mass spectrometry

    Digital Repository Service at National Institute of Oceanography (India)

    Alagarsamy, R.; You, C.-F.; Nath, B; SijinKumar, A.V.

    Downcore variation of rare earth elements (REEs) in the authigenic Fe-Mn oxides of a sediment core (covering a record of last approx. 40 kyr) from the Andaman Sea, a part of the Indian Ocean shows distinctive positive Ce and Eu anomalies...

  4. PPy/graphene nanosheets/rare earth ions: A new composite electrode material for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wanhong [Experiment Center of Northwest University for Nationalities, Lanzhou 730030 (China); Mo, Zunli, E-mail: mozl@163.com [College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2013-05-01

    Highlights: ► Highly conductive PPy/graphene nanosheets/rare earth ions composites were prepared via in situ polymerization. ► Systematic studies revealed that the GNS and RE{sup 3+} may be simultaneously contributed to increase of the conductivity of PPy/GNS/RE{sup 3+} composites. ► A specific capacitance of as high as 238 F/g at a current density of 1 A/g was achieved over the PPy/GNS/Eu{sup 3+} composite. -- Abstract: Highly conductive PPy/graphene nanosheets/rare earth ions (PPy/GNS/RE{sup 3+}) composites were prepared via in situ polymerization with p-toluenesulfonic acid as a dopant and FeCl{sub 3} as an oxidant. The effects of GNS and RE{sup 3+} on the electrical conductivity of the composites were investigated. The results showed that the GNS as a filler had effect on the conductivity of PPy/GNS/RE{sup 3+} composites, which played an important role in forming a conducting network in PPy matrix. The microstructures of GNS and PPy/GNS/RE{sup 3+} were characterized by the SEM and TEM examinations. It was found that GNS and PPy nanospheres formed a uniform composite with the PPy nanospheres absorbed on the GNS surface and/or filled between the GNS. Such uniform structure together with the observed high conductivities afforded high specific capacitance when used as supercapacitor electrodes. A specific capacitance of as high as 238 F/g at a current density of 1 A/g was achieved over the PPy/GNS/Eu{sup 3+} composite.

  5. Hyperspectral REE (Rare Earth Element Mapping of Outcrops—Applications for Neodymium Detection

    Directory of Open Access Journals (Sweden)

    Nina Kristine Boesche

    2015-04-01

    Full Text Available In this study, an in situ application for identifying neodymium (Nd enriched surface materials that uses multitemporal hyperspectral images is presented (HySpex sensor. Because of the narrow shape and shallow absorption depth of the neodymium absorption feature, a method was developed for enhancing and extracting the necessary information for neodymium from image spectra, even under illumination conditions that are not optimal. For this purpose, the two following approaches were developed: (1 reducing noise and analyzing changing illumination conditions by averaging multitemporal image scenes and (2 enhancing the depth of the desired absorption band by deconvolving every image spectrum with a Gaussian curve while the rest of the spectrum remains unchanged (Richardson-Lucy deconvolution. To evaluate these findings, nine field samples from the Fen complex in Norway were analyzed using handheld X-ray fluorescence devices and by conducting detailed laboratory-based geochemical rare earth element determinations. The result is a qualitative outcrop map that highlights zones that are enriched in neodymium. To reduce the influences of non-optimal illumination, particularly at the studied site, a minimum of seven single acquisitions is required. Sharpening the neodymium absorption band allows for robust mapping, even at the outer zones of enrichment. From the geochemical investigations, we found that iron oxides decrease the applicability of the method. However, iron-related absorption bands can be used as secondary indicators for sulfidic ore zones that are mainly enriched with rare earth elements. In summary, we found that hyperspectral spectroscopy is a noninvasive, fast and cost-saving method for determining neodymium at outcrop surfaces.

  6. Geology and market-dependent significance of rare earth element resources

    Science.gov (United States)

    Simandl, G. J.

    2014-12-01

    China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

  7. The Effect of Fulvic Acid on the Leaching of a Weathered Rare-Earth Ore

    Science.gov (United States)

    Luo, Xian-ping; Feng, Bo; Wang, Peng-cheng; Zhou, He-peng; Chen, Xiao-ming

    2015-12-01

    The effect of fulvic acid on the leaching of a weathered crust elution-deposited rare-earth ore, using ammonium sulfate as lixiviant, has been investigated. The results show that fulvic acid can enhance the leaching process effectively. With the addition of fulvic acid to the lixiviant at a concentration of 0.1 wt pct, the leaching extraction of rare-earth elements increased by 8.38 pct and the ammonium sulfate concentration decreased by 25 wt pct. Fulvic acid promotes the leaching process. It also reacts with rare-earth ions, forms soluble complexes, reduces the activity of the leached rare-earth ions, and increases the concentration difference of ion diffusion. These results highlight a new approach for making the leaching process of low-grade weathered crust elution-deposited rare-earth ore more efficient and also for lowering the lixiviant consumption.

  8. Resonant Inelastic X-ray Scattering of Rare-Earth and CopperSystems

    Energy Technology Data Exchange (ETDEWEB)

    Kvashnina, Kristina [Uppsala Univ. (Sweden)

    2007-07-11

    Rare earths and copper systems were studied using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The use of monochromased synchotron radiation and improved energy resolution for RIXS made possible to obtain valuable information on the electronic structure in 4f, 5f and 3d systems. Experimental results for rare-earths (Ho, Gd, Cm, U, Np, Pu) were analyzed by atomic multiplet theory based on the Hartree-Fock calculations. The inelastic scattering structures in RIXS spectra at 5d edge of actinides found to be sensitive to actinide oxidation states in different systems. Comparison of experimental and calculated Cm 5d RIXS spectra gave direct information about valency of the 248-curium isotope in oxide. Scientific understanding of processes that control chemical changes of radioactive species from spent fuel is improved by studying interactions of actinide ions (U, Np, Pu) with corroded iron surfaces. RIXS measurements at the actinide 5d edge found to be sensitive to actinide oxidation states in different systems. Comparison of experimental and calculated Cm 5d RIXS spectra gave direct information about valency of the 248 curium isotope in oxide. Scientific understanding of processes that control chemical changes of radioactive species from spent fuel is improved by studying interactions of actinide ions (U, Np, Pu) with corroded iron surfaces. RIXS measurements at the actinide 5d edge indicate the reduction of U(VI), NP(V) and Pu(VI) to U(IV), Np(IV) and Pu(IV) by presence of iron ions. This thesis is also addressed to the study of changes in the electronic structure of copper films during interaction with synthetic groundwater solutions. The surface modifications induced by chemical reactions of oxidized 100 Angstrom Cu films with CL-, SO42- and HCO3- ions in aqueous solutions with various concentrations were studied in-situ using XAS. It was shown that the pH value, the

  9. Calculating Absolute Transition Probabilities for Deformed Nuclei in the Rare-Earth Region

    Science.gov (United States)

    Stratman, Anne; Casarella, Clark; Aprahamian, Ani

    2017-09-01

    Absolute transition probabilities are the cornerstone of understanding nuclear structure physics in comparison to nuclear models. We have developed a code to calculate absolute transition probabilities from measured lifetimes, using a Python script and a Mathematica notebook. Both of these methods take pertinent quantities such as the lifetime of a given state, the energy and intensity of the emitted gamma ray, and the multipolarities of the transitions to calculate the appropriate B(E1), B(E2), B(M1) or in general, any B(σλ) values. The program allows for the inclusion of mixing ratios of different multipolarities and the electron conversion of gamma-rays to correct for their intensities, and yields results in absolute units or results normalized to Weisskopf units. The code has been tested against available data in a wide range of nuclei from the rare earth region (28 in total), including 146-154Sm, 154-160Gd, 158-164Dy, 162-170Er, 168-176Yb, and 174-182Hf. It will be available from the Notre Dame Nuclear Science Laboratory webpage for use by the community. This work was supported by the University of Notre Dame College of Science, and by the National Science Foundation, under Contract PHY-1419765.

  10. The rare-earth elements: Vital to modern technologies and lifestyles

    Science.gov (United States)

    Van Gosen, Bradley S.; Verplanck, Philip L.; Long, Keith R.; Gambogi, Joseph; Seal, Robert R.

    2014-01-01

    Until recently, the rare-earth elements (REEs) were familiar to a relatively small number of people, such as chemists, geologists, specialized materials scientists, and engineers. In the 21st century, the REEs have gained visibility through many media outlets because of (1) the public has recognized the critical, specialized properties that REEs contribute to modern technology, as well as (2) China's dominance in production and supply of the REEs and (3) international dependence on China for the majority of the world's REE supply.Since the late 1990s, China has provided 85–95 percent of the world’s REEs. In 2010, China announced their intention to reduce REE exports. During this timeframe, REE use increased substantially. REEs are used as components in high technology devices, including smart phones, digital cameras, computer hard disks, fluorescent and light-emitting-diode (LED) lights, flat screen televisions, computer monitors, and electronic displays. Large quantities of some REEs are used in clean energy and defense technologies. Because of the many important uses of REEs, nations dependent on new technologies, such as Japan, the United States, and members of the European Union, reacted with great concern to China’s intent to reduce its REE exports. Consequently, exploration activities intent on discovering economic deposits of REEs and bringing them into production have increased.

  11. Intermode beating mode-locking technique for a rare-earth-doped fiber pulsed laser.

    Science.gov (United States)

    Luo, Zhengqian; Yang, Runhua; Du, Tuanjie; Ruan, Qiujun; Li, Weiwei; Chen, Nan

    2017-08-01

    In this paper, we report the intermode beating mode-locking of a 2  μm Tm 3+ -doped fiber laser (TDFL) pumped by a 1565 nm continuous-wave multi-longitudinal-mode laser. Because strong intermode beating of the 1565 nm pump source induces the periodic modulation of 2 μm intracavity power, stable mode-locking of the TDFL is successfully established by precisely matching the 2 μm cavity frequency with the intermode-beating frequency of the 1565 nm pump source. The mode-locked laser, without requiring any specific mode-locking element, can stably emit the rectangular nanosecond pulses. The mode-locking operation at the center wavelength of 1980.35 nm has a >61  dB signal-to-noise ratio and a 34.496 MHz repetition rate. Although the preliminary results are not better than those of conventional mode-locking, intermode beating mode-locking in combination with rare-earth-doped fiber lasers could provide a promising and alternative solution for compact, low-cost, and high-performance pulsed laser sources.

  12. Behaviour of Rare Earth Elements during the Earth's core formation

    Science.gov (United States)

    Faure, Pierre; Bouhifd, Mohamed Ali; Boyet, Maud; Hammouda, Tahar; Manthilake, Geeth

    2017-04-01

    Rare Earth Elements (REE) are classified in the refractory group, which means that they have a high temperature condensation and their volatility-controlled fractionation is limited to high-temperature processes. Anomalies have been measured for Eu, Yb and Sm, which are the REE with the lowest condensation temperatures in CAIs and chondrules (e.g. [1]). REE are particularly abundant in the sulfides of enstatite chondrites, 100 to 1000 times the CI value [e.g. 2,3], proving that these elements are not strictly lithophile under extremely reducing conditions. However by investigating experimentally the impact of Earth's core formation on the behavior of Sm and Nd, we have shown the absence of fractionation between Sm and Nd during the segregation of the metallic phase [4]. Recently, Wohlers and Wood [5] proposed that Nd and Sm could be fractionated in presence of a S-rich alloy phase. However, their results were obtained at pressure and temperature conditions below the plausible conditions of the Earth's core formation. Clearly, large pressure range needs to be covered before well-constrained model can be expected. Furthermore, our preliminary metal-silicate partitioning results show that Ce and Eu have higher metal/silicate partition coefficients than their neighboring elements, and that the presence of sulphur enhances the relative difference between partition coefficients. In this presentation, we will present and discuss new metal-silicate partition coefficients of all REE at a deep magma ocean at pressures ranging from those of the uppermost upper mantle ( 5 GPa) to a maximum pressure expected in the range of 20 GPa, temperatures ranging from 2500 to about 3000 K, and oxygen fugacities within IW-1 to IW-5 (1 to 5 orders of magnitude lower than the iron-wüstite buffer). We will discuss the effect of S, as well as the effect of H2O on the behaviour of REE during the Earth's core formation: recent models suggest that contrary to currently accepted beliefs, the

  13. Anomalous high pressure behaviour in nanosized rare earth sesquioxides

    Energy Technology Data Exchange (ETDEWEB)

    Dilawar, Nita; Varandani, Deepak; Mehrotra, Shalini; Bandyopadhyay, Ashis K [Pressure and Vacuum Standards, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110012 (India); Poswal, Himanshu K; Sharma, Surinder M [High Pressure Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2008-03-19

    We report Raman spectroscopic studies of the nanosized rare earth sesquioxides, namely yttrium sesquioxide (Y{sub 2}O{sub 3}), gadolinium sesquioxide (Gd{sub 2}O{sub 3}) and samarium sesquioxide (Sm{sub 2}O{sub 3}), under high pressure. The samples were characterized using x-ray diffraction, Raman spectroscopy and atomic force microscopy at atmospheric pressures. Y{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} were found to be cubic at ambient, while Sm{sub 2}O{sub 3} was found to be predominantly cubic with a small fraction of monoclinic phase. The strongest Raman peaks are observed at 379, 344 and 363 cm{sup -1}, respectively, for Y{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}. All the samples were found to be nanosized with 50-90 nm particle sizes. The high pressures were generated using a Mao-Bell type diamond anvil cell and a conventional laser Raman spectrometer is used to monitor the pressure-induced changes. Y{sub 2}O{sub 3} seems to undergo a crystalline to partial amorphous transition when pressurized up to about 19 GPa, with traces of hexagonal phase. However, on release of pressure, the hexagonal phase develops into the dominant phase. Gd{sub 2}O{sub 3} is also seen to develop into a mixture of amorphous and hexagonal phases on pressurizing. However, on release of pressure Gd{sub 2}O{sub 3} does not show any change and the transformation is found to be irreversible. On the other hand, Sm{sub 2}O{sub 3} shows a weakening of cubic phase peaks while monoclinic phase peaks gain intensity up to about a pressure of 6.79 GPa. However, thereafter the monoclinic phase peaks also reduce in intensity and mostly disordering sets in which does not show significant reversal as the pressure is released. The results obtained are discussed in detail.

  14. Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds.

    Science.gov (United States)

    Pindwal, Aradhana; Yan, KaKing; Patnaik, Smita; Schmidt, Bradley M; Ellern, Arkady; Slowing, Igor I; Bae, Cheolbeom; Sadow, Aaron D

    2017-11-07

    Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)3}3 (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI3THFn and 3 equiv of KC(SiHMe2)3. X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C3-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)3}3 and DFT calculations. The Ln↼HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in 1a (ΔH(⧧) = 8.2(4) kcal·mol(-1); ΔS(⧧) = -1(2) cal·mol(-1)K(-1)) and 1a-d9 (ΔH(⧧) = 7.7(3) kcal·mol(-1); ΔS(⧧) = -4(2) cal·mol(-1)K(-1)). Comparisons of lineshapes, rate constants (kH/kD), and slopes of ln(k/T) vs 1/T plots for 1a and 1a-d9 reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five β-Si-H⇀Ln and one γ-C-H⇀Ln. The calculations also suggest the pathway for Ln↼HSi/SiH exchange involves rotation of a single C(SiHMe2)3 ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 °C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)3}3 and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox(Me2))2) give {MeC(Ox(Me2))2}Ln{C(SiHMe2)3}2, and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).

  15. Structure and properties of intermetallic ternary rare earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Casper, Frederick

    2008-12-17

    The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

  16. [Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

    Science.gov (United States)

    Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

    2013-05-01

    A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

  17. Radiological Impacts and Regulation of Rare Earth Elements in Non-Nuclear Energy Production

    Directory of Open Access Journals (Sweden)

    Timothy Ault

    2015-03-01

    Full Text Available Energy industries account for a significant portion of total rare earth usage, both in the US and worldwide. Rare earth minerals are frequently collocated with naturally occurring radioactive material, imparting an occupational radiological dose during recovery. This paper explores the extent to which rare earths are used by various non-nuclear energy industries and estimates the radiological dose which can be attributed to these industries on absolute and normalized scales. It was determined that typical rare earth mining results in an occupational collective dose of approximately 0.0061 person-mSv/t rare earth elements, amounting to a total of 330 person-mSv/year across all non-nuclear energy industries (about 60% of the annual collective dose from one pressurized water reactor operated in the US, although for rare earth mining the impact is spread out over many more workers. About half of the collective dose from non-nuclear energy production results from use of fuel cracking catalysts for oil refining, although given the extent of the oil industry, it is a small dose when normalized to the energy equivalent of the oil that is used annually. Another factor in energy industries’ reliance on rare earths is the complicated state of the regulation of naturally occurring radiological materials; correspondingly, this paper also explores regulatory and management implications.

  18. Mechanical Properties of Magnesium-Rare Earth Alloy Systems: A Review

    Directory of Open Access Journals (Sweden)

    Sravya Tekumalla

    2014-12-01

    Full Text Available Magnesium-rare earth based alloys are increasingly being investigated due to the formation of highly stable strengthening phases, activation of additional deformation modes and improvement in mechanical properties. Several investigations have been done to study the effect of rare earths when they are alloyed to pure magnesium and other Mg alloys. In this review, the mechanical properties of the previously investigated different magnesium-rare earth based binary alloys, ternary alloys and other higher alloys with more than three alloying elements are presented.

  19. The LSF and MTF of rare-earth oxysulfide intensifying screens.

    Science.gov (United States)

    Arnold, B A; Eisenberg, H; Bjärngard, B E

    1976-11-01

    The line spread function (LSF) and modulation transfer function (MTF) of 9 rare-earth screen/film systems were measured and compared with those of two fast calcium tungstate systems, using double-emulsion films sandwiched between two screens and mounted in regular cassettes. The LSFs were found to fit exponential functions. These results indicate that the increased sensitivity of rare-earth phosphors over calcium tungstate can be used to construct screens with a higher MTF or increased speed. The fast rare-earth systems allow the use of smaller focal spots for increased resolution while reducing the radiation dose to the patient.

  20. Growth, structure and lattice dynamics of rare earth silicide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Anja

    2015-07-13

    In the present thesis the epitaxial growth, crystal structure, stoichiometry, thermal stability and lattice dynamics of self-organized EuSi{sub 2} and DySi{sub 2} films, nanoislands and nanowires are investigated. The rare earth silicide (RESi) nanostructures have attracted considerable interest due to their high conductivity, very low Schottky barrier heights, remarkable chemical stability, self-organization in high area density and defects-free nano-objects with tunable size and shape, and the direct integration into the Si technology. The extensive research is driven by the continuous downscaling of the CMOS electronics that require new approaches in the devices architecture and circuits interconnects. Although RESi nanostructures attracted a lot of interest already several years ago and a lot of research has been done in this field, the lattice dynamics of these materials are still unknown. Recent developments at third generation synchrotron radiation sources have brought their performance to a stage where phonon spectroscopy of nanostructures and thin layers became feasible using nuclear inelastic X-ray scattering. This novel experimental technique is based on the process of phonon-assisted nuclear resonant absorption/emission of X-rays from the nuclei of Moessbauer-active isotopes. The method provides direct access to the phonon density of states (DOS) of the investigated element. Together with the ab initio calculations it was possible to get a comprehensive understanding of the lattice dynamics. EuSi{sub 2} films and nanoislands and DySi{sub 2} films, nanoislands and nanowires have been grown on the vicinal Si(001) surface by molecular beam epitaxy. While DySi{sub 2} was grown following known growth procedures, the growth conditions for EuSi{sub 2} had to be established first. EuSi{sub 2} was grown at two different growth conditions to study the influence of crystal structure and morphology upon different growth temperatures. The structure has been

  1. Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

    Indian Academy of Sciences (India)

    annealed at 900–1200 ◦C for 240 min in Ar. X-ray diffraction analysis, field emission–scanning electron microscope and fluorescent ... powders with regular shape and narrow size distribution confirmed by FE–SEM observation, strong red emission at. 615 nm .... ing in the particle size increase and crystallization improves.

  2. Red-emitting alkaline-earth rare-earth pentaoxometallates powders ...

    Indian Academy of Sciences (India)

    Precursor pyrolyzed at 500 °C for 240 min was finally annealed at 900–1200 °C for 240 min in Ar. X-ray diffraction analysis, field emission–scanning electron microscope and fluorescent spectrophotometer were used to evaluate structural and optical properties. For the 1000 °C-annealed powders with regular shape and ...

  3. Ternary rare-earth based alternative gate-dielectrics for future integration in MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Juergen; Lopes, Joao Marcelo; Durgun Oezben, Eylem; Luptak, Roman; Lenk, Steffi; Zander, Willi; Roeckerath, Martin [IBN 1-IT, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2009-07-01

    The dielectric SiO{sub 2} has been the key to the tremendous improvements in Si-based metal-oxide-semiconductor (MOS) device performance over the past four decades. It has, however, reached its limit in terms of scaling since it exhibits a leakage current density higher than 1 A/cm{sup 2} and does not retain its intrinsic physical properties at thicknesses below 1.5 nm. In order to overcome these problems and keep Moore's law ongoing, the use of higher dielectric constant (k) gate oxides has been suggested. These high-k materials must satisfy numerous requirements such as the high k, low leakage currents, suitable band gap und offsets to silicon. Rare-earth based dielectrics are promising materials which fulfill these needs. We will review the properties of REScO{sub 3} (RE = La, Dy, Gd, Sm, Tb) and LaLuO{sub 3} thin films, grown with pulsed laser deposition, e-gun evaporation or molecular beam deposition, integrated in capacitors and transistors. A k > 20 for the REScO{sub 3} (RE = Dy, Gd) and around 30 for (RE = La, Sm, Tb) and LaLuO{sub 3} are obtained. Transistors prepared on SOI and sSOI show mobility values up to 380 cm{sup 2}/Vs on sSOI, which are comparable to such prepared with HfO{sub 2}.

  4. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  5. Optical and rheological study of gamma irradiated rare-earth nanoparticle based ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Nibedita [Nanoscience and Soft Matter Laboratory, Department of Physics, Tezpur University, PO Napaam, Tezpur 784 028, Assam (India); Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in [Nanoscience and Soft Matter Laboratory, Department of Physics, Tezpur University, PO Napaam, Tezpur 784 028, Assam (India); Department of Physics, School of Engineering and Applied Sciences, Harvard University, MA 02138 (United States); Saha, Abhijit [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8 Bidhannagar, Kolkata 700 098 (India)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Gd{sub 2}O{sub 3} nanoparticle based ferrofluids have been produced with ethanol as carrier medium. Black-Right-Pointing-Pointer PL emission show improvement in defect related emission with {gamma}-irradiation dose. Black-Right-Pointing-Pointer The ferrofluids show shear thinning behavior with bi-exponential decay characteristics. Black-Right-Pointing-Pointer Fast and slow components are found to increase with irradiation dose. - Abstract: The present work reports on the optical and rheological properties of unexposed and gamma irradiated rare-earth (RE) oxide nanoparticle-based ferrofluids (FF). The ferrofluids were prepared by dispersing surfactant coated gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticles in ethanol medium and later on subjected to energetic gamma irradiation (1.25 MeV) at select doses. As predicted from transmission electron microscopy and X-ray diffraction (XRD) studies, the synthesized nanoparticles are of {approx}7 nm size which crystallize into cubic crystal structure. The photoluminescence response reveals creation of defect states on nanoparticle surfaces when FFs are subjected to gamma irradiation. Whereas, rheology measurements showed unusual shear thinning behavior of the ferrofluids. The flow behavior of all the samples can be correlated to the bi-exponential decay curve fitting which reveals that decay phenomenon is governed by two independent mechanism: fast and slow events. The variation of the decay parameter with irradiation dose is attributed to the creation of point defects and weakening of inter nanoparticle bonding.

  6. Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

    Science.gov (United States)

    Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

    2015-08-18

    The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

  7. Development of AL{sub 2}O{sub 3} - ZrO{sub 2} ceramic composite reinforced with rare earth oxides (Y{sub 2}O)3) for inert coating of storage and transport systems of crude petroleum; Desenvolvimento de composito ceramico Al{sub 2}O{sub 3} - ZrO{sub 2} reforcada com oxido de terra rara para sistema de armazenamento e transporte de petroleo cru

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J.C.; Yadava, Y.P.; Sanguinetti Ferreira, R.A.; Albuquerque, L.T., E-mail: juliana.carvalhosilva@ufpe.br [Universidade Federal de Pernambuco (UFPE), Jaboatao de Guararapes, PE (Brazil). Centro de Tecnologia. Departamento de Engenharia Mecanica

    2014-07-01

    The advancement of the oil sector has generated the need for the use of materials resistant to aggressive environments to oil. Although ceramics have high melting point and high hardness is, on the other hand, more fragile and less tough, which can cause damage to the metal structure. The Al{sub 2}O{sub 3} based ceramics reinforced with rare earth oxide can improve tenaciousness and makes the ceramic material more resistant. This article aims to present the production of composite Al{sub 2}O{sub 3} - Y{sub 2}O{sub 3} stabilized ZrO{sub 2} by uniaxial pressing, following sintering (1200-1350 deg C). Structural and microstructural characterizations as XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) and mechanical tests as Vickers hardness, % absorption and % linear shrinkage were conducted to evaluate the feasibility of using the composite and ceramic coating for storage and transportation of oil tanks. The results indicate that the proportions of 5%, 10% and 30% ZrO{sub 2} make it suitable as a good composite suitable coating. (author)

  8. Two main and a new type rare earth elements in Mg alloys: A review

    Science.gov (United States)

    Kong, Linghang

    2017-09-01

    Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

  9. Rare Earth or Cosmic Zoo: Testing the Frequency of Complex Life in the Universe

    Science.gov (United States)

    Bains, W.; Schulze-Makuch, D.

    2017-02-01

    We propose how to test between two major hypotheses about the frequency of life in the universe (Rare Earth and Cosmic Zoo) using future remote sensing capabilities targeted at exoplanets and site visits of planetary bodies in our solar system.

  10. Rare earth element patterns of the Central Indian Basin sediments related to their lithology

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Roelandts, I.; Sudhakar, M.; Pluger, W.L.

    Rare earth element (REE) concentration have been determined in terrigenous, siliceous (nodule barren and nodule bearing), calcareous, and red clay from the Central Indian Basin. The bulk distribution of REE, and in particular the relative cerium...

  11. Assessment of trading partners for China's rare earth exports using a decision analytic approach.

    Science.gov (United States)

    He, Chunyan; Lei, Yalin; Ge, Jianping

    2014-01-01

    Chinese rare earth export policies currently result in accelerating its depletion. Thus adopting an optimal export trade selection strategy is crucial to determining and ultimately identifying the ideal trading partners. This paper introduces a multi-attribute decision-making methodology which is then used to select the optimal trading partner. In the method, an evaluation criteria system is established to assess the seven top trading partners based on three dimensions: political relationships, economic benefits and industrial security. Specifically, a simple additive weighing model derived from an additive utility function is utilized to calculate, rank and select alternatives. Results show that Japan would be the optimal trading partner for Chinese rare earths. The criteria evaluation method of trading partners for China's rare earth exports provides the Chinese government with a tool to enhance rare earth industrial policies.

  12. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    Science.gov (United States)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

  13. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I SBIR program is to develop polymer derived rare earth silicate nanocomposite environmental barrier coatings (EBC) for providing...

  14. Diagenetic remobilization of rare earth elements in a sediment core from the central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Banakar, V.K.

    Rare earth elements (REE) distribution in a 36 cm long sediment box core from the Central Indian Basin is studied. REE concentration is generally higher in the upper oxic zone than in intermediate suboxic zone suggesting REE diffusion upwards...

  15. A political economy of China's export restrictions on rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Pothen, Frank [Zentrum fuer Europaeische Wirtschaftsforschung GmbH (ZEW), Mannheim (Germany); Fink, Kilian [Frankfurt Univ. (Germany)

    2015-04-20

    We investigate why governments restrict exports of exotic raw materials taking rare earth elements as a case study. Trade restrictions on exotic materials do not have immediate macroeconomic effects. Relocating rare earth intensive industries is found to be the main reason behind China's export barriers. They are part of a more extensive strategy aiming at creating comparative advantages in these sectors and at overcoming path dependencies. Moreover, export barriers serve as a second-best instrument to reduce pollution and to slow down the depletion of exhaustible resources. Growing domestic rare earth consumption renders those increasingly ineffective. Rising reliance on mine-site regulation indicates that this fact is taken into account. Rare earth extraction is dominated by a few large companies; the demand side is dispersed. That speaks against successful lobbying for export restrictions. It appears as if the export barriers are set up to compensate mining firms.

  16. Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

    Directory of Open Access Journals (Sweden)

    Escudero Alberto

    2017-06-01

    Full Text Available Rare earth based nanostructures constitute a type of functional materials widely used and studied in the recent literature. The purpose of this review is to provide a general and comprehensive overview of the current state of the art, with special focus on the commonly employed synthesis methods and functionalization strategies of rare earth based nanoparticles and on their different bioimaging and biosensing applications. The luminescent (including downconversion, upconversion and permanent luminescence and magnetic properties of rare earth based nanoparticles, as well as their ability to absorb X-rays, will also be explained and connected with their luminescent, magnetic resonance and X-ray computed tomography bioimaging applications, respectively. This review is not only restricted to nanoparticles, and recent advances reported for in other nanostructures containing rare earths, such as metal organic frameworks and lanthanide complexes conjugated with biological structures, will also be commented on.

  17. Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

    Science.gov (United States)

    Schwandt, Craig S.; McKay, Gordon A.

    1997-01-01

    Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.

  18. Alloying Characteristics of the Rare Earth Elements with the Transition Elements

    National Research Council Canada - National Science Library

    Elliott, Rodney

    1964-01-01

    The alloying characteristics of the rare earth elements with the transition metals undergo a radical change as the atomic number of the transition series increases - - transition elements in Groups...

  19. Spectroscopy and Device Performance of Rare Earth Doped III-Nitrides

    National Research Council Canada - National Science Library

    Hommerich, Uwe

    2002-01-01

    The recent demonstration of visible thin-film electroluminescence (TFEL) devices based on rare earth doped GaN has spurred great interest in this class of materials for possible applications in full color displays...

  20. Polymer Derived Rare Earth Silicate Nanocomposite Protective Coatings for Nuclear Thermal Propulsion Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Leveraging a rapidly evolving state-of-the-art technical base empowered by Phase I NASA SBIR funding, NanoSonic's polymer derived rare earth silicate EBCs will...

  1. Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

    Science.gov (United States)

    Escudero, Alberto; Becerro, Ana I.; Carrillo-Carrión, Carolina; Núñez, Nuria O.; Zyuzin, Mikhail V.; Laguna, Mariano; González-Mancebo, Daniel; Ocaña, Manuel; Parak, Wolfgang J.

    2017-06-01

    Rare earth based nanostructures constitute a type of functional materials widely used and studied in the recent literature. The purpose of this review is to provide a general and comprehensive overview of the current state of the art, with special focus on the commonly employed synthesis methods and functionalization strategies of rare earth based nanoparticles and on their different bioimaging and biosensing applications. The luminescent (including downconversion, upconversion and permanent luminescence) and magnetic properties of rare earth based nanoparticles, as well as their ability to absorb X-rays, will also be explained and connected with their luminescent, magnetic resonance and X-ray computed tomography bioimaging applications, respectively. This review is not only restricted to nanoparticles, and recent advances reported for in other nanostructures containing rare earths, such as metal organic frameworks and lanthanide complexes conjugated with biological structures, will also be commented on.

  2. Rare earth element distribution and behaviour in buried manganese nodules from the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Banakar, V.K.

    ) 303-312 303 Elsevier Science Publishers B.V., Amsterdam Rare earth element distribution and behaviour in buried manganese nodules from the Central Indian Basin J.N. Pattan and V.K. Banakar National Institute of Oceanography, Dona Paula, Goa 403004..., India (Received September 15, 1992; revision accepted January 6, 1993) ABSTRACT Pattan, J.N. and Banakar, V.K., 1993. Rare earth element distribution and behaviour in buried manganese nodules from the Central Indian Basin. Mar. Geol., 112: 303...

  3. Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology

    OpenAIRE

    Moriwaki, Hiroshi; YAMAMOTO, Hiroki

    2013-01-01

    In recent years, rare earth elements (REEs) have been widely used in various modern technological devices and the global demand for REE has been increasing. The increased demand for REEs has led to environmental exposure or water pollution from rare earth metal mines and various commercial products. Therefore, the development of a safe technology for the separation and adsorption of REEs is very important from the perspective of green chemistry and environmental pollution. In this review, the...

  4. Antiferromagnetic correlations in icosahedral R-Mg-Zn quasicrystals (R rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, B.; Schmitt, D. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Powder neutron-diffraction experiments performed on R-Mg-Zn quasicrystals have shown for the first time the existence of magnetic ordering of the rare earth in these systems at low temperature (T{sub c} {<=} 6.5 K depending on the rare earth). Both narrow and broad magnetic diffraction peaks have been observed showing the presence of two different scales of magnetic correlations. (author). 3 refs.

  5. Voltage Control of Rare-Earth Magnetic Moments at the Magnetic-Insulator-Metal Interface

    Science.gov (United States)

    Leon, Alejandro O.; Cahaya, Adam B.; Bauer, Gerrit E. W.

    2018-01-01

    The large spin-orbit interaction in the lanthanides implies a strong coupling between their internal charge and spin degrees of freedom. We formulate the coupling between the voltage and the local magnetic moments of rare-earth atoms with a partially filled 4 f shell at the interface between an insulator and a metal. The rare-earth-mediated torques allow the power-efficient control of spintronic devices by electric-field-induced ferromagnetic resonance and magnetization switching.

  6. Theoretical and Computational Studies of Rare Earth Substitutes: A Test-bed for Accelerated Materials Development

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, Lorin X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    Hard permanent magnets in wide use typically involve expensive Rare Earth elements. In this effort, we investigated candidate permanent magnet materials which contain no Rare Earths, while simultaneously exploring improvements in theoretical methodology which enable the better prediction of magnetic properties relevant for the future design and optimization of permanent magnets. This included a detailed study of magnetocrystalline anisotropy energies, and the use of advanced simulation tools to better describe magnetic properties at elevated temperatures.

  7. Chemical burnup determination based on spectrophotometric measurement of total rare earth fission products, uranium, and plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, S.F.; Ortiz, M.R.; Rein, J.E.

    1975-10-01

    A chemical burnup procedure incorporates the ion-exchange separation of uranium, plutonium, and total rare earth fission products (as the fission monitor) followed by the spectrophotometric determination of each. The separation involves retaining uranyl and plutonyl chloride complexes on a macroporous anion exchange column from 12 M HCl, whereas the rare earths and most fission products pass through. Subsequently, plutonium is eluted with 0.1 M HI-12 M HCl and uranium with 0.1 M HCl. From the initial effluent of the first column, the rare earth group is separated on a second column of either (1) macroporous anion exchange resin from HNO/sub 3/-CH/sub 3/OH, or (2) pellicular cation exchange particles from HCl-C/sub 2/H/sub 5/OH. The HNO/sub 3/--CH/sub 3/OH system normally is used to separate the rare earth group from fuel cladding elements and other fission products. The HCl--C/sub 2/H/sub 5/OH system additionally separates the rare earth group from americium. Arsenazo III is the chromogenic agent for the spectrophotometric determination of the separated uranium, plutonium, and rare earth fractions.

  8. Efficient manganese luminescence induced by Ce3+-Mn2+ energy transfer in rare earth fluoride and phosphate nanocrystals

    Directory of Open Access Journals (Sweden)

    Ding Yun

    2011-01-01

    Full Text Available Abstract Manganese materials with attractive optical properties have been proposed for applications in such areas as photonics, light-emitting diodes, and bioimaging. In this paper, we have demonstrated multicolor Mn2+ luminescence in the visible region by controlling Ce3+-Mn2+ energy transfer in rare earth nanocrystals [NCs]. CeF3 and CePO4 NCs doped with Mn2+ have been prepared and can be well dispersed in aqueous solutions. Under ultraviolet light excitation, both the CeF3:Mn and CePO4:Mn NCs exhibit Mn2+ luminescence, yet their output colors are green and orange, respectively. By optimizing Mn2+ doping concentrations, Mn2+ luminescence quantum efficiency and Ce3+-Mn2+ energy transfer efficiency can respectively reach 14% and 60% in the CeF3:Mn NCs.

  9. Environmental geochemistry reflected by rare earth elements in Bohai Bay (North China) core sediments.

    Science.gov (United States)

    Xu, Ya-Yan; Song, Jin-Ming; Duan, Li-Qin; Li, Xue-Gang; Zhang, Ying; Sun, Pei-Yan

    2010-08-05

    In Bohai Bay sediment, two cores were collected to estimate the source of sediments, and assess the environmental changes. Sequential extractions were carried out in this study. Rare earth elements (REE) were leached out from four labile fractions: Exchangeable (L1), Bound to carbonates (L2), Bound to Fe-Mn oxides (L3), Bound to organic matter (L4), and the remainder was Residual (R5). The percentages of REE in different fractions follow the order: R5 > L3 > L2 > L4 > L1. With heavy REE depletion and no pronounced REE fractionation, NASC-normalized REE patterns of Bohai Bay sediments are quite consistent with that of Haihe River sediment, which is the key river of Bohai Bay. Y/Ho ratios of total contents are all much lower than the average value of continental crust, while Y/Ho ratios of L2 are higher than those of other fractions. Based on the patterns of REE and Y/Ho ratios of samples, sediments of Bohai Bay mainly come from terrigenous matters, which are mainly brought by Haihe River. And REE combined with carbonates may be partly inherited from anthropogenic matter. Moreover, environmental changes exert significant influences on the patterns and fractionations of REE, and they can be deduced from the characteristics of REE. Our results on the patterns and burial fluxes of REE reflect two environmental changes: Bohai Bay has been shifting towards more reducing conditions in the last one hundred years, and there was a large flood in 1939.

  10. Structural investigation of the negative thermal expansion in yttrium and rare earth molybdates

    Energy Technology Data Exchange (ETDEWEB)

    Guzman-Afonso, Candelaria; Torres, Manuel Eulalio; Sabalisck, Nanci; Sanchez-Fajardo, VIctor [Departamento de Fisica Basica, Universidad de La Laguna, Tenerife (Spain); Gonzalez-Silgo, Cristina; Gonzalez-Platas, Javier [Departamento de Fisica Fundamental II, Universidad de La Laguna, Tenerife (Spain); Lozano-GorrIn, Antonio Diego [Servicio Integrado de Difraccion de Rayos X, Universidad de La Laguna, Tenerife (Spain); Campo, Javier [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza (Spain); RodrIguez-Carvajal, Juan, E-mail: csilgo@ull.es [Institut Laue-Langevin, Grenoble (France)

    2011-08-17

    The Sc{sub 2}(WO{sub 4}){sub 3}-type phase (Pbcn) of Y{sub 2}(MoO{sub 4}){sub 3}, Er{sub 2}(MoO{sub 4}){sub 3} and Lu{sub 2}(MoO{sub 4}){sub 3} has been prepared by the conventional solid-state synthesis with preheated oxides and the negative thermal expansion (NTE) has been investigated along with an exhaustive structural study, after water loss. Their crystal structures have been refined using the neutron and x-ray powder diffraction data of dehydrated samples from 150 to 400 K. The multi-pattern Rietveld method, using atomic displacements with respect to a known structure as parameters to refine, has been applied to facilitate the interpretation of the NTE behavior. Polyhedral distortions, transverse vibrations of A{center_dot}{center_dot}{center_dot}O-Mo (A = Y and rare earths) binding oxygen atoms, non-bonded distances A{center_dot}{center_dot}{center_dot}Mo and atomic displacements from the high temperature structure, have been evaluated as a function of the temperature and the ionic radii.

  11. Modification of Non-Metallic Inclusions by Rare-Earth Elements in Microalloyed Steels

    Directory of Open Access Journals (Sweden)

    M. Opiela

    2012-04-01

    Full Text Available The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels was discussed in the paper. The investigated steels are assigned to production of forged elements by thermo- mechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0 g per 1 kg of steel. It was found that using material charge of high purity and a realization of metallurgical process in vacuous conditions result in a low concentration of sulfur (0.004%, phosphorus (from 0.006 to 0.008% and oxygen (6 ppm. The high metallurgical purity is confirmed by a small fraction of non-metallic inclusions averaging 0.075%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean size 17m2. The chemical composition and morphology of non-metallic inclusions was modified by Ce, La and Nd, what results a small deformability of non- metallic inclusions during hot-working.

  12. Rare Earth Element Behaviour in Apatite from the Olympic Dam Cu–U–Au–Ag Deposit, South Australia

    Directory of Open Access Journals (Sweden)

    Sasha Krneta

    2017-08-01

    Full Text Available Apatite is a common magmatic accessory in the intrusive rocks hosting the giant ~1590 Ma Olympic Dam (OD iron-oxide copper gold (IOCG ore system, South Australia. Moreover, hydrothermal apatite is a locally abundant mineral throughout the altered and mineralized rocks within and enclosing the deposit. Based on compositional data for zoned apatite, we evaluate whether changes in the morphology and the rare earth element and Y (REY chemistry of apatite can be used to constrain the fluid evolution from early to late hydrothermal stages at OD. The ~1.6 Ga Roxby Downs granite (RDG, host to the OD deposit, contains apatite as a magmatic accessory, locally in the high concentrations associated with mafic enclaves. Magmatic apatite commonly contains REY-poor cores and REY-enriched margins. The cores display a light rare earth element (LREE-enriched chondrite-normalized fractionation pattern with a strong negative Eu anomaly. In contrast, later hydrothermal apatite, confined to samples where magmatic apatite has been obliterated due to advanced hematite-sericite alteration, displays a conspicuous, convex, middle rare earth element (MREE-enriched pattern with a weak negative Eu anomaly. Such grains contain abundant inclusions of florencite and sericite. Within high-grade bornite ores from the deposit, apatite displays an extremely highly MREE-enriched chondrite-normalized fractionation trend with a positive Eu anomaly. Concentrations of U and Th in apatite mimic the behaviour of ∑REY and are richest in magmatic apatite hosted by RDG and the hydrothermal rims surrounding them. The shift from characteristic LREE-enriched magmatic and early hydrothermal apatite to later hydrothermal apatite displaying marked MREE-enriched trends (with lower U, Th, Pb and ∑REY concentrations reflects the magmatic to hydrothermal transition. Additionally, the strong positive Eu anomaly in the MREE-enriched trends of apatite in high-grade bornite ores are attributable to

  13. An x-ray absorption spectroscopic study of the electronic structure and bonding of rare-earth orthoferrites

    Science.gov (United States)

    Hayes, J. R.; Grosvenor, A. P.

    2011-11-01

    Rare-earth orthoferrites, REFeO3 (RE=rare earth; Y), are tremendously adaptable compounds that are being investigated for use in a wide variety of applications including gas sensors, vehicle catalytic converters, and solid-oxide fuel cells. They also exhibit interesting magnetic properties such as high-temperature antiferromagnetism, making them useful for data storage applications. The compounds adopt a distorted perovskite-type structure where the tilt angle of the octahedra increases (Fe-O-Fe bond angle decreases) as the size of the rare-earth atom decreases. Despite intensive study of the physical properties of these compounds, very few studies have investigated how the bonding and electronic structure of these systems change with substitution of the RE. X-ray absorption near-edge spectroscopy (XANES) is a technique well-suited for such a study, and, in view of this, Fe L-, Fe K- and O K-edge spectra from a series of REFeO3 compounds (RE=La, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y) have been collected, and are presented here. Fe L-edge spectra show that Fe is octahedrally coordinated and that the Fe-centered octahedra do not appear to distort with changes in the identity of the RE. The Fe K-edge spectra contain an intersite hybrid peak, which is an ill-studied feature that is attributed to non-local transitions of 1s electrons to 3d states on the next-nearest-neighbor atom that are hybridized with 4p states on the absorbing atom through O 2p states. In this study, it is shown that the intensity of this feature is strongly dependent on the Fe-O-Fe bond angle; the lower the Fe-O-Fe bond angle, the less intense the intersite hybrid peak is.

  14. Quantum efficiency of silica-coated rare-earth doped yttrium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes-Vásquez, D., E-mail: dcervant@cnyn.unam.mx [Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana No. 3918, Zona Playitas, C.P. 22860 Ensenada, B.C., México (Mexico); Contreras, O.E.; Hirata, G.A. [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, B.C., México (Mexico)

    2013-11-15

    The photoluminescent properties of rare earth-activated white-emitting Y{sub 2}SiO{sub 5}:Ce,Tb nanocrystalline phosphor prepared by two different methods, pressure-assisted combustion synthesis and sol–gel, were studied. The synthesized phosphor samples were post-annealed at 1373 K and 1623 K in order to obtain the X1-Y{sub 2}SiO{sub 5} and X2-Y{sub 2}SiO{sub 5} phases, respectively, which were confirmed by X-ray diffraction measurements. Photoluminescence analysis showed the contribution of two blue-emission bands within the 380–450 nm region originating from 5d–4f transitions in Ce{sup 3+} ions and a well-defined green emission of Tb{sup 3+} ions located at 545 nm corresponding to {sup 5}D{sub 4}→{sup 7}F{sub 5} electronic transitions. Thereafter, Y{sub 2}SiO{sub 5}:Ce,Tb powders were coated with colloidal silica in order to investigate the effect of silica coatings on their luminescent properties. Absolute fluorescence quantum efficiency measurements were carefully performed, which revealed an increase of 12% of efficiency in coated compared with bare-Y{sub 2}SiO{sub 5}:Ce,Tb phosphor. -- Highlights: • Y{sub 2}SiO{sub 5}:Ce,Tb phosphor powders were successfully coated with colloidal silica. • Post-annealing treatments improved the quantum efficiency of silica-coated Y{sub 2}SiO{sub 5}:Ce,Tb phosphors. • Absolute fluorescence quantum efficiency measurements showed an increase of 12%.

  15. Near UV-Blue Excitable Green-Emitting Nanocrystalline Oxide

    Directory of Open Access Journals (Sweden)

    C. E. Rodríguez-García

    2011-01-01

    Full Text Available Green-emitting Eu-activated powders were produced by a two-stage method consisting of pressure-assisted combustion synthesis and postannealing in ammonia. The as-synthesized powders exhibited a red photoluminescence (PL peak located at =616 nm when excited with =395 nm UV. This emission peak corresponds to the 5D0→7F2 transition in Eu3+. After annealing in ammonia, the PL emission changed to an intense broad-band peak centered at =500 nm, most likely produced by 4f65d1→4f7 electronic transitions in Eu2+. This green-emitting phosphor has excitation band in the near UV-blue region (=300–450 nm. X-ray diffraction analysis reveals mainly the orthorhombic EuAlO3 and Al2O3 phases. Transmission electron microscopy observations showed that the grains are formed by faceted nanocrystals (~4 nm of polygonal shape. The excellent excitation and emission properties make these powders very promising to be used as phosphors in UV solid-state diodes coupled to activate white-emitting lamps.

  16. Study of compounds emitted during thermo-oxidative decomposition of polyester fabrics

    Directory of Open Access Journals (Sweden)

    Dzięcioł Małgorzata

    2016-03-01

    Full Text Available Compounds emitted during thermo-oxidative decomposition of three commercial polyester fabrics for indoor outfit and decorations (upholstery, curtains were studied. The experiments were carried out in a flow tubular furnace at 600°C in an air atmosphere. During decomposition process the complex mixtures of volatile and solid compounds were emitted. The main volatile products were carbon oxides, benzene, acetaldehyde, vinyl benzoate and acetophe-none. The emitted solid compounds consisted mainly of aromatic carboxylic acids and its derivatives, among which the greatest part took terephthalic acid, monovinyl terephthalate and benzoic acid. The small amounts of polycyclic aromatic hydrocarbons were also emitted. The emission profiles of the tested polyester fabrics were similar. The presence of toxic compounds indicates the possibility of serious hazard for people during fire.

  17. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junghwan, E-mail: JH.KIM@lucid.msl.titech.ac.jp; Miyokawa, Norihiko; Ide, Keisuke [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Toda, Yoshitake [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan)

    2016-01-15

    We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS) because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  18. [Application of ICP-MS to Detect Rare Earth Elements in Three Economic Macroalgaes in China].

    Science.gov (United States)

    Zhao, Yan-fang; Shang, De-rong; Zhai, Yu-xiu; Ning, Jin-song; Ding, Hai-yan; Sheng, Xiao-feng

    2015-11-01

    In order to investigate the content and distribution of rare earth elements (REE) in main economic macroalgaes in our country, fifteen rare earth elements in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed that the total content of REE in different species of macroalgaes was different. The highest total content of REE was in Enteromorpha (16,012.0 ng · g⁻¹), while in kelp and laver, the total REE was similar for two macroalgaes (3887.4 and 4318.1 ng · g⁻¹ respectively). The content of fifteen rare earth elements in kelp ranged from 7.9 to 1496.4 ng · g⁻¹; in laver, it ranged from 8.2 to 1836.6 ng · g⁻¹. For Enteromorpha, the concentration of 15 rare earth elements were between 19.2 and 6014.5 ng · g⁻¹. In addition, the content and distribution of different rare earth elements in different macroalgaes was also different. For kelp, the highest content of REE was Ce (1 496.4 ng · g⁻¹), and the second was La (689.1 ng · g⁻¹). For laver, the highest was Y (1836.6 ng · g⁻¹), and the second was Ce (682.2 ng · g⁻¹). For Enteromorpha, the highest was Ce (6014.5 ng · g⁻¹), and the second was La (2902.9 ng · g⁻¹). Present results also showed that three macroalgaes accumulated the light rare earth elements much more than the high rare earth elements. The light rare earth elements occupied 90.9%, 87.3% and 91.1% for kelp, laver and Enteromorpha respectively. The result that the Enteromorpha had high content of rare earth elements could provide important support for opening new research directions for the utilization of Enteromorpha.

  19. Prospective analysis of the flows of certain rare earths in Europe at the 2020 horizon.

    Science.gov (United States)

    Rollat, Alain; Guyonnet, Dominique; Planchon, Mariane; Tuduri, Johann

    2016-03-01

    This paper proposes a forecast of certain rare earth flows in Europe at the 2020 horizon, based on an analysis of trends influencing various actors of the rare earth industry along the value chain. While 2020 is indicated as the forecast horizon, the analysis should be considered as more representative of the next decade. The rare earths considered here are used in applications that are important for a low-carbon energy transition and/or have a significant recycling potential: NdFeB magnets (Pr, Nd, Dy), NiMH batteries (Pr, Nd) and fluorescent lamp phosphors (Eu, Tb, Y). An analysis of major trends affecting the rare earth industry in Europe along the value chain (including extraction, separation, fabrication, manufacture, use and recycling), helps to build a scenario for a material flow analysis of these rare earths in Europe. The scenario assumes in particular that during the next decade, there exists a rare earth mine in production in Europe (with Norra Kärr in Sweden as a most likely candidate) and also that recycling is in line with targets proposed in recent European legislation. Results are presented in the form of Sankey diagrams which help visualize the various flows for the three applications. For example, calculations forecast flows from extraction to separation of Pr, Nd and Dy for magnet applications in Europe, on the order of 310 tons, 980 tons and 80 tons rare earth metal resp., while recycled flows are 35 tons, 110 tons and 30 tons resp. Calculations illustrate how the relative contribution of recycling to supply strongly depends on the situation with respect to demand. Considering the balance between supply and demand, it is not anticipated any significant shortage of rare earth supply in Europe at the 2020 horizon, barring any new geopolitical crisis involving China. For some heavy rare earths, supply will in fact largely outweigh demand, as for example Europium due to the phasing out of fluorescent lights by LEDs. Copyright © 2016 Elsevier Ltd

  20. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources.

    Science.gov (United States)

    Ganem, Joseph; Bowman, Steven R

    2013-11-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence.

  1. Rare earth-modified kaolin/NaY-supported Pd-Pt bimetallic catalyst for the catalytic combustion of benzene.

    Science.gov (United States)

    Zuo, Shufeng; Sun, Xuejie; Lv, Ningning; Qi, Chenze

    2014-08-13

    A new type of porous kaolin/NaY composite (KL-NY) with a large specific surface area and large pore sizes was synthesized through a one-step crystallization process, and rare earth-modified KL-NY-supported Pd-Pt catalysts were studied for benzene combustion. The results indicated that the pore volume and specific surface area of KL-NY after calcination and crystallization were 0.298 cm(3)/g and 365 m(2)/g, respectively, exhibiting appropriate pore structure and good thermal stability. Catalysts with rare earth metals greatly enhanced the activity of Pd/KL-NY, and the addition of Pt and Ce into the Pd catalyst improved the catalytic activity as well as the stability. The catalyst with an optimal Ce content and Pt/Pd molar ratio (0.2%Pd-Pt (6:1)/6%Ce/KL-NY) demonstrated the best activity for the complete oxidation of benzene at 230 °C, and the catalyst above maintained the 100% benzene conversion for 960 h.

  2. Leaching of rare earth elements from fluorescent powder using the tea fungus Kombucha.

    Science.gov (United States)

    Hopfe, Stefanie; Flemming, Katrin; Lehmann, Falk; Möckel, Robert; Kutschke, Sabine; Pollmann, Katrin

    2017-04-01

    In most modern technologies such as flat screens, highly effective magnets and lasers, as well as luminescence phosphors, Rare Earth Elements (REE) are used. Unfortunately no environmentally friendly recycling process exists so far. In comparison to other elements the interaction of microorganisms with REE has been studied to a less extent. However, as REE are ubiquitously present in nature it can be assumed that microorganisms play an important role in the biogeochemistry of REE. This study investigates the potential of organic acid-producing microbes for extracting REE from industrial waste. In Germany, 175 tons of fluorescent phosphor (FP) are collected per year as a distinct fraction from the recycling of compact fluorescent lamps. Because the FP contains about 10% of REE-oxides bound in the so-called triband dyes it is a readily accessible secondary resource of REE. Using the symbiotic mixed culture Kombucha, consisting of yeasts and acetic acid bacteria, REE were leached at a significant rate. The highest leaching-rates were observed in shake cultures using the entire Kombucha-consortium or its supernatant as leaching agent compared to experiments using the isolates Zygosaccharomyces lentus and Komagataeibacter hansenii as leaching organisms. During the cultivation, the pH decreased as a result of organic acid production (mainly acetic and gluconic acid). Thus, the underlying mechanism of the triband dye solubilisation is probably linked to the carboxyl-functionality or a proton excess. In accordance with the higher solubility of REE-oxides compared to REE-phosphates and -aluminates, the red dye Y 2 O 3 :Eu 2+ containing relatively expensive REE was shown to be preferentially solubilized. These results show that it is possible to dissolve the REE-compounds of FP with the help of microbial processes. Moreover, they provide the basis for the development of an eco-friendly alternative to the currently applied methods that use strong inorganic acids or toxic

  3. Rare Earth Dopant (Nd, Gd, Dy, and Er Hybridization in Lithium Tetraborate

    Directory of Open Access Journals (Sweden)

    Tony D. Kelly

    2014-05-01

    Full Text Available The four dopants (Nd, Gd, Dy, and Er substitutionally occupy the Li+ sites in lithium tetraborate (Li2B4O7: RE glasses as determined by analysis of the extended X-ray absorption fine structure. The dopants are coordinated by 6-8 oxygen at a distance of 2.3 to 2.5 Å, depending on the rare earth. The inverse relationship between the RE¬ O coordination distance and rare earth (RE atomic number is consistent with the expected lanthanide atomic radial contraction with increased atomic number. Through analysis of the X-ray absorption near edge structure, the rare earth dopants adopt the RE3+ valence state. There are indications of strong rare earth 5d hybridization with the trigonal and tetrahedral formations of BO3 and BO4 based on the determination of the rare earth substitutional Li+ site occupancy from the X-ray absorption near edge structure data. The local oxygen disorder around the RE3+ luminescence centers evident in the structural determination of the various glasses, and the hybridization of the RE3+ dopants with the host may contribute to the asymmetry evident in the luminescence emission spectral lines. The luminescence emission spectra are indeed characteristic of the expected f-to-f transitions; however, there is an observed asymmetry in some emission lines.

  4. The Link between Rare-Earth Peak Formation and the Astrophysical Site of the R Process

    Science.gov (United States)

    Mumpower, Matthew R.; McLaughlin, Gail C.; Surman, Rebecca; Steiner, Andrew W.

    2016-12-01

    The primary astrophysical source of the rare-earth elements is the rapid neutron capture process (r process). The rare-earth peak that is seen in the solar r-process residuals has been proposed to originate as a pile-up of nuclei during the end of the r process. We introduce a new method utilizing Monte Carlo studies of nuclear masses in the rare-earth region, that includes self-consistently adjusting β-decay rates and neutron capture rates, to find the mass surfaces necessary for the formation of the rare-earth peak. We demonstrate our method with two types of astrophysical scenario, one corresponding to conditions typical of hot winds from core-collapse supernovae and stellar-mass accretion disks, and one corresponding to conditions typical of the ejection of the material from the tidal tails of neutron star mergers. In each type of astrophysical condition, this method successfully locates a region of enhanced stability in the mass surface that is responsible for the rare-earth peak. For each scenario, we find that the change in the mass surface has qualitatively different features, thus future measurements can shed light on the type of environment in which the r process occurred.

  5. Bioavailable concentrations of germanium and rare earth elements in soil fractions

    Science.gov (United States)

    Hentschel, Werner; Wiche, Oliver

    2015-04-01

    As there is an increasing demand for germanium and the rare earth elements due to their diverse application in modern technologies (optical cables, permanent magnets in wind power stations), there is an interest to investigate a new approach to extract these ubiquitous but disperse existing elements - via Phytomining. But before this method can be established, a thorough understanding of processes regarding the intake of germanium (Ge) and the rare earth elements (REEs) is necessary. The aim of this work was to get insights or hints on correlations between the concentrations and the fractionation of Ge and REEs in the soil and the concentrations in plants - in other words we wanted to conduct research on bioavailable concentrations of Ge and REEs in soil fractions. On 18 sites situated around Freiberg, Saxony we took samples of soil and plants. To extract the elements from the plant material a decomposition with hydrofluoric acid was used. The soil samples was examined by a sequential extraction with seven steps (mobile, carbonatic, oxidisable, amorphic oxides, crystalline oxides, phytoliths and secondary clay minerals, residual or siliceous). The amounts of the REEs showed a high correlation between each other, so neodymium can be regarded as a proxy for all REEs. The average total amount of Ge in the soil samples was around 1.45 mg/kg, the one of neodymium (Nd) was around 25 mg/kg. Both values equal the overall average in the earth crust. Concerning the Ge concentration in soil the residual siliceous fractions constituted for 70% of total, whereas the fractions V and VI - dedicated as crystalline oxides and phytoliths/secondary clay minerals - made out for 25%. Only 5% of the total amount of Ge in soil accounted for the fractions I to IV. There was found a statistical significant correlation between the absolute Ge concentrations in these latter soil fractions with the Ge concentration in plant material of the same site. Therefore it seems that the fractions I to

  6. Cross Relaxation in rare-earth-doped oxyfluoride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lakshminarayana, G.; Weis, Eric M. [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lira, A.C. [Unidad Académica Profesional Nezahualcóyotl, Universidad Autónoma del Estado de México, Av. Bordo de Xochiaca s/n, Nezahualcóyotl, Estado de Mexico 57000, México (Mexico); Caldiño, Ulises [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, México D.F. 09340 (Mexico); Williams, Darrick J. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hehlen, Markus P., E-mail: hehlen@lanl.gov [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-07-15

    The excited-state relaxation dynamics of Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} doped into a 50SiO{sub 2}–20Al{sub 2}O{sub 3}–10Na{sub 2}O–20LaF{sub 3} (mol%) oxyfluoride glass are studied. Multiphonon relaxation of the primary emitting states in Tb{sup 3+} ({sup 5}D{sub 3} and {sup 5}D{sub 4}), Sm{sup 3+} ({sup 4}G{sub 5/2}), and Eu{sup 3+} ({sup 5}D{sub 0}) was found to be negligible in the present host. The relaxation of Tb{sup 3+} ({sup 5}D{sub 4}) and Eu{sup 3+} ({sup 5}D{sub 0}) is dominated by radiative decay. For Tb{sup 3+} ({sup 5}D{sub 3}) and Sm{sup 3+} ({sup 4}G{sub 5/2}) in contrast, radiative relaxation is in competition with several non-radiative cross-relaxation processes. This competition was found to be particularly pronounced for the {sup 5}D{sub 3} excited state in Tb{sup 3+}, where a 124-fold decrease of the ({sup 5}D{sub 3}→{sup 7}F{sub 5})/({sup 5}D{sub 4}→{sup 7}F{sub 5}) emission intensity ratio and a ∼10-fold shortening of the {sup 5}D{sub 3} lifetime was observed upon increasing the Tb{sup 3+} concentration from 0.01% to 1%. The Tb{sup 3+} concentration dependence of {sup 5}D{sub 3} also points to some degree of ion aggregation in the “as quenched” glasses. A Judd–Ofelt intensity analysis was performed for Sm{sup 3+} and used to estimate the relative magnitude of {sup 4}G{sub 5/2} cross-relaxation processes. Four cross-relaxation processes in particular were identified to account for 92% of the total {sup 4}G{sub 5/2} non-radiative decay, and a 11% quantum efficiency was estimated for the {sup 4}G{sub 5/2} excited state. Non-exponentiality in the {sup 5}D{sub 0} decay of Eu{sup 3+} is evidence for several Eu{sup 3+} coordination environments in the glass host that manifest in different {sup 5}D{sub 0} decay constants because of the hypersensitivity of the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. -- Highlights: ► Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} were doped into a LaF{sub 3}-rich oxyfluoride glass. ► The

  7. Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

    Science.gov (United States)

    Saha, Abhijit; Deb, S. B.; Nagar, B. K.; Saxena, M. K.

    An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO3) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100 mg of the refractory oxide using a mixture of sulphuric acid (H2SO4), phosphoric acid (H3PO4) and water (H2O) with 1400 W power, 10 min ramp and 60 min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250 mg L- 1. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥ 90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1-5 ng L- 1 and 7-64 μg kg- 1 respectively.

  8. Synthesis and photoluminescence properties of novel Schiff base type polymer-rare earth complexes containing furfural-based bidentate Schiff base ligands

    Science.gov (United States)

    Gao, Baojiao; Zhang, Dandan; Li, Yanbin

    2018-03-01

    Luminescent polymer-rare earth complexes are an important class of photoluminescence and electroluminescence materials. Via molecular design, two furfural-based bidentate Schiff base ligands, furfural-aniline (FA) type ligand and furfural-cyclohexylamine (FC) type ligand, were bonded on the side chains of polysulfone (PSF), respectively, forming two functionalized macromolecules, PSF-FA and PSF-FC. And then through respective coordination reactions of the two functionalized macromolecules with Eu(Ⅲ) ion and Tb(Ⅲ) ion, novel luminescent binary and ternary (with 1,10-phenanthroline as the second ligand) polymer-rare earth complexes were synthesized. For these complexes, on basis of the characterization of their chemical structures, they photoluminescence properties were main researched, and the relationship between their luminescent properties and structures was explored. The experimental results show that the complexes coming from PSF-FA and Eu(Ⅲ) ion including binary and ternary complexes emit strong red luminescence, indicating that the bonded bidentate Schiff base ligand FA can sensitize the fluorescence emission of Eu(III) ion. While the complexes coming from PSF-FC and Tb(Ⅲ) ion produce green luminescence, displaying that the bonded bidentate Schiff base ligand FC can sensitize the fluorescence emission of Tb(Ⅲ) ion. The fluorescence emission intensities of the ternary complexes were stronger than that of binary complexes, reflecting the important effect of the second ligand. The fluorescence emission of the solid film of complexes is much stronger than that of the solutions of complexes. Besides, by comparison, it is found that the furfural (as a heteroaromatic compound)-based Schiff base type polymer-rare earth complexes have stronger fluorescence emission and higher energy transfer efficiency than salicylaldehyde (as a common aromatic compound)-based Schiff base type polymer-rare earth complexes.

  9. Synthesis of vertically aligned metal oxide nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-03-03

    Metal oxide nanostructure and methods of making metal oxide nanostructures are provided. The metal oxide nanostructures can be 1 -dimensional nanostructures such as nanowires, nanofibers, or nanotubes. The metal oxide nanostructures can be doped or undoped metal oxides. The metal oxide nanostructures can be deposited onto a variety of substrates. The deposition can be performed without high pressures and without the need for seed catalysts on the substrate. The deposition can be performed by laser ablation of a target including a metal oxide and, optionally, a dopant. In some embodiments zinc oxide nanostructures are deposited onto a substrate by pulsed laser deposition of a zinc oxide target using an excimer laser emitting UV radiation. The zinc oxide nanostructure can be doped with a rare earth metal such as gadolinium. The metal oxide nanostructures can be used in many devices including light-emitting diodes and solar cells.

  10. Mössbauer study of the effect of rare earth substitution into montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E., E-mail: kuzmann@caesar.elte.hu; Singh, L. H.; Garg, V. K.; Oliveira, A. C. de [University of Brasília, Institute of Physics (Brazil); Kovács, E. M.; Molnár, Á. M. [University of Debrecen, Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary); Homonnay, Z. [Eötvös Loránd University, Institute of Chemistry (Hungary); Kónya, P. [Geological and Geophysical Institute of Hungary (Hungary); Nagy, N. M.; Kónya, J. [University of Debrecen, Isotope Laboratory, Department of Colloid and Environmental Chemistry (Hungary)

    2016-12-15

    Novel montmorillonites were prepared by the exchange of the interlayer cations with a series of rare earth cations (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Er) and characterized by XRD, XRF, SEM, chemical analysis and {sup 57}Fe Mössbauer spectroscopy. An unexpected magnetically split component, assigned to iron being in the interlayer space, was observed in the Mössbauer spectra at 78 K in some rare earth cation exchanged montmorillonite. This paper is the initial report about this observation. The transition of iron from the octahedral site to the interlayer and possible incorporation of rare earths in sites different from those which are in the interlayer space was concluded.

  11. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Saleh A. Alkahtani

    2016-01-01

    Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

  12. Crystal fields at light rare-earth ions in Y and Lu

    DEFF Research Database (Denmark)

    Touborg, P.; Nevald, Rolf; Johansson, Torben

    1978-01-01

    in Y and Lu hosts, indicating that these values for a specific rare-earth solute in Y and Lu may give a reliable estimate for the corresponding sites in rare-earth metal. This is confirmed for Pr, for which these values and the value of B20 deduced from paramagnetic-susceptibility measurements......Crystal-field parameters have been deduced for the light rare-earth solutes Ce, Pr, and Nd in Y or Lu hosts from measurements of the paramagnetic susceptibilities. In the analysis all multiplets in the lowest LS term were included. For a given host, crystal-field parameters divided by Stevens...... on the pure metal, correctly explain the transition observed by neutron spectroscopy and the level crossing observed in a high-field experiment. A weighted average of B20 for cubic and hexagonal sites in Nd and Sm was obtained from the paramagnetic susceptibilities of these metals at high temperatures....

  13. The effect of rare earth elements on the texture and formability of asymmetrically rolled magnesium sheet

    Energy Technology Data Exchange (ETDEWEB)

    Alderman, Dr. Martyn [Magnesium Elektron North America; Cavin, Odis Burl [ORNL; Davis, Dr. Bruce [Magnesium Elektron North America; Muralidharan, Govindarajan [ORNL; Muth, Thomas R [ORNL; Peter, William H [ORNL; Randman, David [Magnesium Elektron North America; Watkins, Thomas R [ORNL

    2011-01-01

    The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare earth elements to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare earth additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare earth additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.

  14. Separation of rare earth by column chromatography using organic resins XAD/DEPHA

    Energy Technology Data Exchange (ETDEWEB)

    Zini, J.; Ferreira, J.C.; Bergamaschi, V.S.; Santos, I.; Carvalho, F.M.S., E-mail: jcferrei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CCCH/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Celulas a Combustivel e Hidrogenio

    2013-07-01

    The designation of light and heavy rare earth was used the fractionation used in separation processes. In this study the process of separation of rare earth, in groups, by chromatographic column consisting in fixing of cations these elements in an organic resin Amberlite XAD16 functionalized with the extracting agent DEPHA and another portion functionalized with a mixture of extractors DEPHA/TOP. The preparation of these resins was performed in two forms, one directly as the extracting agent to the resin and the other to be used in ethyl alcohol. Conditioned resins were introduced in chromatographic columns in separation of groups, light and heavy, using a standard solution of cerium nitrate and standard solution of holmium nitrate groups to represent light and heavy respectively. The characterization technique used to identify the rare earth elements was Spectrometry X-Ray Fluorescence (XRF). The results using the technique of chromatography were satisfactory, obtaining 100% separation of the elements. (author)

  15. Pulsed Ultraviolet Light Emitting Diodes for Advanced Oxidation of Tartrazine

    Science.gov (United States)

    2015-03-26

    very aggressive and powerful oxidants that readily react with most organic compounds. The destructive effects of OH radicals are made possible due to...biofilms associated with periodontitis and peri- implantitis. Photodiagnosis and Photodynamic Therapy, Volume 10, Issue 2, May 2013, Pages 156–167

  16. Sources of nitrous oxide emitted from European forest soils

    DEFF Research Database (Denmark)

    Ambus, P.; Zechmeister-Boltenstern, S.; Butterbach-Bahl, K.

    2006-01-01

    Forest ecosystems may provide strong sources of nitrous oxide (N2O), which is important for atmospheric chemical and radiative properties. Nonetheless, our understanding of controls on forest N2O emissions is insufficient to narrow current flux estimates, which still are associated with great...

  17. Efficient dual-wavelength excitation of Tb3+ emission in rare-earth doped KYF4 cubic nanocrystals dispersed in silica sol-gel matrix

    Science.gov (United States)

    del-Castillo, J.; Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.

    2014-11-01

    Energy transfer from Ce3+ to Tb3+ ions under UV excitation, giving rise to visible emissions, is investigated in sol-gel derived transparent nano-glass-ceramics containing cubic KYF4 nanocrystals, for different doping concentrations of rare-earth ions. Moreover, visible emissions of Tb3+ are also obtained under near-infrared excitation through energy transfer from Yb3+ ions by means of cooperative up-conversion processes. Thus, Ce3+-Tb3+-Yb3+ doped nano-glass-ceramics can be activated in a dual-wavelength mode yielding efficient blue-green emissions of particular interest in photovoltaic silicon solar cells and white-light emitting diodes.

  18. Injection Laser Using Rare Earth Doped GaN Thin Films for Visible and Infrared Applications

    Science.gov (United States)

    2010-05-01

    MBE control software: Crystal V7. Fig 3.3 Spectrum of residual gas analyzer (RGA). Fig 3.4 RHEED pattern on (a) 2d wurtzite and (b) 3d cubic GaN...mixture subflow will help reactant gas of main flow to reach the surface and promote 2D growth but suppress 3D growth. The effect of AlN and GaN buffer...reported by Chu-Kung. 1.3. Rare Earth Elements: Mysterious Lighting Sources Rare earth (RE) elements, also called Lanthanides , include fifteen

  19. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

    Energy Technology Data Exchange (ETDEWEB)

    Malkin, B Z; Zakirov, A R [Kazan State University, Kazan 420008 (Russian Federation); Lummen, T T A; Van Loosdrecht, P H M [Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen (Netherlands); Dhalenne, G, E-mail: boris.malkin@ksu.r [Laboratoire de Physico-Chimie de L' Etat Solide, ICMMO, UMR 8182, Universite Paris-Sud, 91405 Orsay (France)

    2010-07-14

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R{sub 2}Ti{sub 2}O{sub 7} (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

  20. Interfacing superconducting qubits and telecom photons via a rare-earth-doped crystal.

    Science.gov (United States)

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-08

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of π pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered π pulses. We predict total transfer efficiencies on the order of 90%.

  1. [Effects of rare earth elements on soil fauna community structure and their ecotoxicity to Holotrichia parallela].

    Science.gov (United States)

    Li, Guiting; Jiang, Junqi; Chen, Jie; Zou, Yunding; Zhang, Xincai

    2006-01-01

    By the method of OECD filter paper contact, this paper studied the effects of applied rare earth elements on soil fauna community structure and their ecological toxicity to Holotrichia parallela in bean field. The results showed that there were no significant differences between the treatments and the control in soil fauna species, quantity of main species, and diversity index. Urgent and chronic toxic test showed that the differences between the treatments and the control were not significant. It was suggested that within the range of test dosages, rare earth elements had little ecological toxicity to Holotrichia parallela, and did not change the soil fauna community structure.

  2. Shape transition and coexistence in neutron-deficient rare earth isotopes

    CERN Multimedia

    We propose to study spectroscopic quadrupole moments of excited states and electromagnetic transition rates between them in the neutron-deficient rare earth nuclei $^{140}$Sm and $^{142}$Gd using projectile Coulomb excitation at energies of 4.7 MeV per nucleon. The rare earth nuclei below the N=82 shell closure form one of the few regions of the nuclear chart where oblate shapes are expected to occur near the ground state. Nuclear shapes are expected to change rapidly in this region, with coexistence of oblate and prolate shapes in some nuclei. The measurement of electromagnetic matrix elements represents therefore a particularly sensitive test of theoretical nuclear structure models.

  3. On the single-ion Magnetic Anisotropy of the Rare-Earth Metals

    DEFF Research Database (Denmark)

    Kolmakova, N.P.; Tishin, A.M.; Bohr, Jakob

    1996-01-01

    The temperature dependences of the single-ion magnetic anisotropy constants for Tb and Dy metals are calculated in terms of the multipole moments of the rare-earth ions utilizing the available crystal-field parameters. The results are compared with the existing experimental data.......The temperature dependences of the single-ion magnetic anisotropy constants for Tb and Dy metals are calculated in terms of the multipole moments of the rare-earth ions utilizing the available crystal-field parameters. The results are compared with the existing experimental data....

  4. Rare earth conversion coatings grown on AA6061 aluminum alloys. Corrosion studies

    Energy Technology Data Exchange (ETDEWEB)

    Brachetti S, S. B. [Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo y Sor Juana I. de la Cruz, Col. Los Mangos, 89440 Ciudad Madero, Tanaulipas (Mexico); Dominguez C, M. A.; Torres H, A. M.; Onofre B, E. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - Altamira, Carretera Tampico-Puerto Industrial Altamira Km. 14.5, 89600 Altamira, Tamaulipas (Mexico); De la Cruz H, W., E-mail: mdominguezc@ipn.mx [UNAM, Centro de Nanociencias y Nanotecnologia, Apdo. Postal 2681, 22800 Ensenada, Baja California (Mexico)

    2014-07-01

    The present work is aimed to investigate the corrosion resistance of rare earth protective coatings deposited by spontaneous deposition on AA6061 aluminum alloy substrates. Coatings were deposited from water-based Ce(NO{sub 3}){sub 3} and La(NO{sub 3}){sub 3} solutions by varing parameters such as rare earth solution concentration, bath temperature and immersion time. The values of the Tafel slopes indicate that the cathodic process is favored by concentration polarization rather than activation polarization. Chemical and morphological characterizations of the surface before and after electrochemical evaluations were performed by X-ray photoelectron spectroscopy and scanning electron microscopy. (Author)

  5. Rare earth element mineralogy and geochemistry in a laterite profile from Madagascar

    DEFF Research Database (Denmark)

    Berger, Alfons; Janots, Emilie; Gnos, Edwin

    2014-01-01

    In this study, rare earth element (REE) distribution has been investigated in a weathering profile from central Madagascar. Combination of bulk rock geochemical data (elements and isotopes) with mineral characterization reveals a remarkable evolution of the REE abundances and REE-minerals in the ......In this study, rare earth element (REE) distribution has been investigated in a weathering profile from central Madagascar. Combination of bulk rock geochemical data (elements and isotopes) with mineral characterization reveals a remarkable evolution of the REE abundances and REE...

  6. Synthesis and Characterization of Rare Earth Corrole-Phthalocyanine Heteroleptic Triple-Decker Complexes.

    Science.gov (United States)

    Lu, Guifen; Li, Jing; Yan, Sen; Zhu, Weihua; Ou, Zhongping; Kadish, Karl M

    2015-06-15

    We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole-phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M2[Pc(OC4H9)8]2[Cor(ClPh)3], where Pc = phthalocyanine, Cor = corrole, and M is Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), or Tb(III). The Y(III) derivative with OC4H9 Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y2[Pc(OC5H11)8]2[Cor(ClPh)3] was synthesized and characterized in a similar manner. The molecular structure of Eu2[Pc(OC4H9)8]2[Cor(ClPh)3] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with E1/2 values being linearly related to the ionic radius of the central ions. The energy (E) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole-phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles.

  7. The potential of sedimentary foraminiferal rare earth element patterns to trace water masses in the past

    Science.gov (United States)

    Osborne, Anne H.; Hathorne, Ed C.; Schijf, Johan; Plancherel, Yves; Böning, Philipp; Frank, Martin

    2017-04-01

    Dissolved rare earth element (REE) concentration data from intermediate and deep seawater form an array characterized by higher middle-REE enrichments (MREE/MREE*) in the North Atlantic and a progressive increase in heavy-to-light REE ratios (HREE/LREE) as water masses age. The REEs in foraminifera are fractionated toward higher MREE/MREE* and lower HREE/LREE relative to seawater. Calculations based on a scavenging model show that the REE patterns in uncleaned core-top foraminifera resemble those adsorbed onto calcite, particulate organic material, and hydrous ferric oxides but the full extent of the REE fractionation measured in foraminifera was not reproduced by the model. However, differences in the HREE/LREE and MREE/MREE* ratios and the cerium anomaly between ocean basins are preserved and are in agreement with the seawater REE distribution. Under oxic conditions, the HREE/LREE and MREE/MREE* compositions of uncleaned foraminifera at the sediment/seawater boundary are preserved during burial but the cerium anomaly is sensitive to burial depth. In suboxic sedimentary environments, all uncleaned foraminiferal REE concentrations are elevated relative to core-top values indicating addition of REEs from pore waters. The HREE/LREE ratio is highest when sedimentation rates were greatest and when high Fe/Ca ratios in the uncleaned foraminifera indicate that Fe was mobile. In sediments that have not experienced suboxic conditions during burial, uncleaned foraminifera preserve the seawater signal taken up at the sediment/seawater interface and are therefore suggested to be a suitable archive of changes in the REE signal of past bottom waters.

  8. Heavy rare earth elements affect early life stages in Paracentrotus lividus and Arbacia lixula sea urchins.

    Science.gov (United States)

    Oral, Rahime; Pagano, Giovanni; Siciliano, Antonietta; Gravina, Maria; Palumbo, Anna; Castellano, Immacolata; Migliaccio, Oriana; Thomas, Philippe J; Guida, Marco; Tommasi, Franca; Trifuoggi, Marco

    2017-04-01

    Heavy rare earth elements (HREEs) have been scarcely studied for their toxicity, in spite of their applications in several technologies. Thus HREEs require timely investigations for their adverse health effects. Paracentrotus lividus and Arbacia lixula embryos and sperm were exposed to trichloride salts of five HREEs (Dy, Ho, Er, Yb and Lu) and to Ce(III) as a light REE (LREE) reference to evaluate: 1) developmental defects (% DD) in HREE-exposed larvae or in the offspring of HREE-exposed sperm; 2) mitotic anomalies; 3) fertilization success; and 4) reactive oxygen species (ROS) formation, and nitric oxide (NO) and malondialdehyde (MDA) levels. Nominal HREE concentrations were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). HREEs induced concentration-related DD increases in P. lividus and A. lixula larvae, ranging from no significant DD increase at 10-7M HREEs up to ≅100% DD at 10-5M HREE. Larvae exposed to 10-5M Ce(III) resulted in less severe DD rates compared to HREEs. Decreased mitotic activity and increased aberration rates were found in HREE-exposed P. lividus embryos. Significant increases in ROS formation and NO levels were found both in HREE-exposed and in Ce(III) embryos, whereas only Ce(III), but not HREEs resulted in significant increase in MDA levels. Sperm exposure to HREEs (10-5-10-4M) resulted in a concentration-related decrease in fertilization success along with increase in offspring damage. These effects were significantly enhanced for Dy(III), Ho(III), Er(III) and Yb(III), compared to Lu(III) and to Ce(III). HREE-associated toxicity affected embryogenesis, fertilization, cytogenetic and redox endpoints showing different toxicities of tested HREEs. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Health effects and toxicity mechanisms of rare earth elements-Knowledge gaps and research prospects.

    Science.gov (United States)

    Pagano, Giovanni; Guida, Marco; Tommasi, Franca; Oral, Rahime

    2015-05-01

    In the recent decades, rare earth elements (REE) have undergone a steady spread in several industrial and medical applications, and in agriculture. Relatively scarce information has been acquired to date on REE-associated biological effects, from studies of bioaccumulation and of bioassays on animal, plant and models; a few case reports have focused on human health effects following occupational REE exposures, in the present lack of epidemiological studies of occupationally exposed groups. The literature is mostly confined to reports on few REE, namely cerium and lanthanum, whereas substantial information gaps persist on the health effects of other REE. An established action mechanism in REE-associated health effects relates to modulating oxidative stress, analogous to the recognized redox mechanisms observed for other transition elements. Adverse outcomes of REE exposures include a number of endpoints, such as growth inhibition, cytogenetic effects, and organ-specific toxicity. An apparent controversy regarding REE-associated health effects relates to opposed data pointing to either favorable or adverse effects of REE exposures. Several studies have demonstrated that REE, like a number of other xenobiotics, follow hormetic concentration-related trends, implying stimulatory or protective effects at low levels, then adverse effects at higher concentrations. Another major role for REE-associated effects should be focused on pH-dependent REE speciation and hence toxicity. Few reports have demonstrated that environmental acidification enhances REE toxicity; these data may assume particular relevance in REE-polluted acidic soils and in REE mining areas characterized by concomitant REE and acid pollution. The likely environmental threats arising from REE exposures deserve a new line of research efforts. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Domestic wastewater treatment using Pt,Ni-RE (rare earth electrodes

    Directory of Open Access Journals (Sweden)

    Eurico Moutinho

    2016-11-01

    Full Text Available Electrochemical technologies can be used for the treatment of domestic wastewaters, by eliminating their organic pollutants. They have advantages over conventional methods, such as environmental compatibility, versatility, energy efficiency, safety and cost. The organic compounds degradation process is based on the production of OH radicals, formed during water electrolysis, which oxidize the organic molecules to CO2. At the same time, hydrogen (H2 is produced through reduction of the water in the effluent, which can be later used in a fuel cell. Present study seeks to find effective electrocatalysts to produce H2 by electrolysis, using domestic wastewaters as the hydrogen source, with or without the addition of supporting electrolyte. Herein KOH is used as the supporting electrolyte, as the extra hydroxide can be used to degrade the organic matter. Nine different electrode materials are evaluated as cathodes for the hydrogen evolution reaction (HER in a domestic wastewater. The tested materials include platinum (Pt and platinum-rare earth (Pt-RE binary alloys, and nickel (Ni and Ni-RE alloys, with the REs being cerium (Ce, samarium (Sm, dysprosium (Dy, and holmium (Ho. Linear scan voltammetry measurements are conducted at temperatures ranging from 25 to 85 ºC. Several kinetic parameters are calculated, such as the Tafel slopes, charge transfer coefficients and exchange current densities. The data obtained at the different electrode materials is compared and it is clear that Pt-RE alloys show superior activity for the HER. It is also noticeable that the wastewater effluent containing the supporting electrolyte leads to significantly better HER performances.

  11. All-solution processed polymer light-emitting diodes with air stable metal-oxide electrodes

    NARCIS (Netherlands)

    de Bruyn, P.; Moet, D. J. D.; Blom, P. W. M.

    We present an all-solution processed polymer light-emitting diode (PLED) using spincoated zinc oxide (ZnO) and vanadium pentoxide (V2O5) as electron and hole injecting contact, respectively. We compare the performance of these devices to the standard PLED design using PEDOT:PSS as anode and Ba/Al as

  12. All-solution processed polymer light-emitting diodes with air stable metal-oxide electrodes

    NARCIS (Netherlands)

    Bruyn, P. de; Moet, D.J.D.; Blom, P.W.M.

    2012-01-01

    We present an all-solution processed polymer light-emitting diode (PLED) using spincoated zinc oxide (ZnO) and vanadium pentoxide (V2O5) as electron and hole injecting contact, respectively. We compare the performance of these devices to the standard PLED design using PEDOT:PSS as anode and Ba/Al as

  13. Enhanced phytoextraction of germanium and rare earth elements - a rhizosphere-based approach

    Science.gov (United States)

    Wiche, Oliver

    2016-04-01

    Germanium (Ge) and rare earth elements (REEs) are economically valuable raw materials that have become an integral part of our modern high tech society. While most of these elements are not actually rare in terms of general amounts in the earth's crust, they are rarely found in sufficient abundances in single locations for their mining to be economically viable. The average concentration of Ge in soils is estimated at 1.6 μg g-1. The REEs comprise a group of 16 elements including La, the group of lanthanides and Y that are abundant in the earth crust with concentrations varying from 35 μg g-1 (La), 40 μg g-1 (Nd), 6 μg g-1 (Gd) and 3.5 μg g-1 (Er) to 0.5 μg g-1 in Tm. Thus, a promising chance to improve supply of these elements could be phytomining. Unfortunately, bioavailability of Ge and REEs in soils appears to be low, in particular in neutral or alkaline soils. A sequential dissolution analysis of 120 soil samples taken from the A-horizons of soils in the area of Freiberg (Saxony, Germany) revealed that only 0.2% of total Ge and about 0.5% of La, Nd, Gd and Er of bulk concentrations were easily accessible by leaching with NH4-acetate (pH 7). Most of the investigated elements were bound to Fe-/Mn-oxides and silicates and were therefore only poorly available for plant uptake. Here we report an environmentally friendly approach for enhanced phytoextraction of Ge and REEs from soils using mixed cultures of plant species with efficient mechanisms for the acquisition of nutrients in the rhizosphere. The rhizosphere is characterized as the zone in soil sourrounding a plant root that consists of a gradient in chemical, physical and biological soil properties driven by rhizodeposits like carboxylates and protons. Some species like white lupin (Lupinus albus) are able to excrete large amounts of organic acid anions(predominantly citrate and malate) and show a particularly high potential for the acidification of the rhizosphere. In our experiments, mixed cultures

  14. Rare Earth and other Chemical Elements Accumulation in Vines of Fogo Island (Cape Verde)

    Science.gov (United States)

    Marques, Rosa; Prudêncio, Maria Isabel; Rocha, Fernando; Dias, Maria Isabel; Franco, Dulce

    2017-04-01

    The Fogo Island is the fourth bigger island of the Cape Verde (central Atlantic Ocean). This archipelago is located 570 kilometres off the coast of West Africa, and is characterized by a semi-arid climate. The volcanic soils of the caldera of this island, with an active volcanism during historical times, have been used for viticulture. The study of uptake of chemical elements by vines - absorption and translocation to grapes - grown in soils developed on alkaline pyroclasts is the main goal of this work. The concentrations of 27 chemical elements in bark, leafs and grapes of two vines, as well as in the corresponding soils ( 50). The bioavailable fraction of Cr and As in these soils may be due to the low percentage of iron oxides (particularly in the form of nanoparticles), which play an important role in the retention of these elements. The factors responsible for the phytoavailability of Sb in soils and its uptake by plants it's still poorly known. Although the Sb concentrations in earth's crust are low, higher concentrations of this element in soils may be related with hydrothermal and volcanic processes. Also, the temperature may influence the accumulation of Sb in plants, with an increase of the Sb uptake by plants at higher temperatures, due to an increased desorption rate of Sb from soil particles. Concerning U, its mobility and dispersion in soils is controlled by its oxidation state, its adsorption capacity in clay minerals or iron oxides, and the ability to form more or less soluble complexes. Although U concentrations in these volcanic soils are low, there is a fraction available for absorption and accumulation by grapes. Concerning the rare earth elements (REE), it should be noted that the light REE are not enriched in any part of the vines studied, and only the heavy REE are enriched in grapes (EF = 20-50); this can be explained by the preferential uptake of the heavy REE, after primary minerals breakdown and the formation of more soluble compounds

  15. Synthesis, characterization and thermal behavior of rare earth amido sulfonates; Sintese, caracterizacao e comportamento termico de amidossulfonatos de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Luiz, Jose Marques; Nunes, Ronaldo Spezia, E-mail: jmluiz@feg.unesp.br [Universidade Estadual Paulista Julio Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia. Departamento de Fisica e Quimica; Matos, Jivaldo do Rosario [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Quimica

    2013-09-01

    Hydrated compounds prepared in aqueous solution by reaction between amidosulfonic acid [H{sub 3}NSO{sub 3}] and suspensions of rare earth hydroxycarbonates [Ln{sub 2}(OH){sub x}(CO{sub 3}){sub y}.zH{sub 2}O] were characterized by elemental analysis (% Ln, % N and % H), infrared spectroscopy (FTIR) and thermogravimetry (TG). The compounds presented the stoichiometry Ln(NH{sub 2}SO{sub 3}){sub 3}.xH{sub 2}O (where x = 1, 5, 2.0 or 3.0). The IR spectra showed absorptions characteristic of H{sub 2}O molecules and NH{sub 2}SO{sub 3} groups. Degree of hydration, thermal decomposition steps and formation of stable intermediates of the type [Ln{sub 2}(SO{sub 4}){sub 3}] and (Ln{sub 2}O{sub 2}SO{sub 4}), besides formation of their oxides, was determined by thermogravimetry. (author)

  16. Crystallographic Stability of Metastable Phase Formed by Containerless Processing in REFeO3 (RE: Rare-Earth Element)

    Science.gov (United States)

    Kuribayashi, Kazuhiko; Kumar, M. S. Vijaya

    2012-01-01

    Undercooling a melt often facilitates a metastable phase to nucleate preferentially. Although the classical nucleation theory shows that the most critical factor for forming a metastable phase is the interface free energy, the crystallographic stability is also indispensable for the phase to be frozen at ambient temperature. In compound materials such as oxides, authors have suggested that the decisive factors for forming a critical nucleus are not only the free energy difference but also the difference of the entropy of fusion between stable and metastable phases. In the present study, using REFeO3 (RE: rare-earth element) as a model material, we investigate the formation of a metastable phase from undercooled melts with respect to the competitive nucleation and crystallographical stabilities of both phases.

  17. Impact of the spectroscopic properties of rare-earth ions on solid-state laser systems

    NARCIS (Netherlands)

    Pollnau, Markus

    The electronic energy level schemes within the 4f subshells of rare-earth ions give rise to a number of fluorescence transitions ranging from the near-UV to the mid-IR spectral region. A large variety of laser lines have been demonstrated based on these fluorescence transitions. Depending on the

  18. Chemical synthesis and characterization of nano-sized rare-earth ...

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... Abstract. The rare-earth ruthenium pyrochlores Ln2Ru2O7 (Ln = La3+, Pr3+, Nd3+, Sm3+ and Gd3+) have been synthesized by the tartrate co-precipitation method, which allowed control of their composition and morphology. The preparation processes were monitored by thermal studies (TG-DTA).

  19. Chemical synthesis and characterization of nano-sized rare-earth ...

    Indian Academy of Sciences (India)

    2

    The above co precipitates of rare-earth ruthenium tartarates were decomposed and calcined slowly at 850oC for ..... Senzaki Y, Hampden-Smith M J, Kodas T T and Hussler J W 1995 J. Am. Ceram. Soc. 78. 2977. 16. Abate C ... Douma M, Chtoun E H, Trijillano R, Rives V. and Khayroun S 2009 Ann. Chim. Sci. Mater. 34 21.

  20. Collaborative study to improve the quality control of rare earth element determinations in environmental matrices

    NARCIS (Netherlands)

    Kramer, K.J.M.; Dorten, W.S.; Groenewoud, H. van het; Haan, E. de; Kramer, G.N.; Monteiro, L.; Muntau, H.; Quevauviller, P.

    1999-01-01

    In order to control the quality of rare earth determinations in environmental matrices, the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna

  1. Collaborative study to improve the quality control of rare earth element determinations in environmental matrices.

    Science.gov (United States)

    Kramer, K J; Dorten, W S; van het Groenewoud, H; de Haan, E; Kramer, G N; Monteiro, L; Muntau, H; Quevauviller, P

    1999-02-01

    In order to control the quality of rare earth determinations in environmental matrices, the Standards, Measurements and Testing Programme (formerly Community Bureau of Reference, BCR) of the European Commission has started a project, the final aim of which is to certify four types of matrices (tuna muscle, mussel tissue, aquatic plant and estuarine sediment) for their contents of a range of rare earth elements (Sc, Y and the lanthanides: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu). The elements U and Th were added to the study. The first part of this project consisted of an interlaboratory study which aimed to test the feasibility of preparation of environmental reference materials and to detect and remove most of the pitfalls observed in rare earth determinations. This paper presents the preparation of the four matrices for the intercomparison study and for the candidate reference material. The main results are presented of the interlaboratory study that was carried out prior to the certification campaign. This collaborative trial is the first attempt ever carried out at this scale to evaluate the state-of-the-art of rare earth determinations in the environment. Its impact on the improvement of chemical measurements will have positive effects on the comparability of data necessary for environmental monitoring.

  2. Low-temperature photoluminescence in chalcogenide glasses doped with rare-earth ions

    Czech Academy of Sciences Publication Activity Database

    Kostka, Petr; Zavadil, Jiří; Iovu, M.S.; Ivanova, Z. G.; Furniss, D.; Seddon, A.B.

    2015-01-01

    Roč. 648, NOV 5 (2015), s. 237-243 ISSN 0925-8388 R&D Projects: GA ČR GAP106/12/2384 Institutional support: RVO:67985891 ; RVO:67985882 Keywords : chalcogenide glasses * rare earth ions * low-temperature photoluminescence * optical transmission Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 3.014, year: 2015

  3. Rare earth metals appliance for magnetic admixtures recovery from mineral premixes

    Directory of Open Access Journals (Sweden)

    A. A. Shevtsov

    2012-01-01

    Full Text Available The analysis of the material composition metallomagnetic admixtures of mineral premix. It is shown that the dressed metallomagnetic impurity includes low-magnetic particles with low magnetic susceptibility. Removing these particles from the product stream in process of magnetic separation using high-energy rare earth magnets is a challenging task.

  4. SUM-RULES FOR MAGNETIC DICHROISM IN RARE-EARTH 4F-PHOTOEMISSION

    NARCIS (Netherlands)

    THOLE, BT; VANDERLAAN, G

    1993-01-01

    We present new sum rules for magnetic dichroism in spin polarized photoemission from partly filled shells which give the expectation values of the orbital and spin magnetic moments and their correlations in the ground state. We apply this to the 4f photoemission of rare earths, where the

  5. Nanophotonic coherent light-matter interfaces based on rare-earth-doped crystals

    Science.gov (United States)

    Zhong, Tian; Kindem, Jonathan M.; Miyazono, Evan; Faraon, Andrei

    2015-09-01

    Quantum light-matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2-4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2~100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light-matter interfaces.

  6. Theory of Temperature Dependence of the Magnetization in Rare-Earth-Transition-Metal Alloys

    DEFF Research Database (Denmark)

    Szpunar, B.; Lindgård, Per-Anker

    1977-01-01

    It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures for Gdl-xTx (T = Co, Ni, and Fe) and Y1-xCox can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition-metal pseudo-...

  7. Absorption spectroscopy of complex rare earth ion doped hybrid materials over a broad wavelength range

    NARCIS (Netherlands)

    Dekker, R.; Worhoff, Kerstin; Stouwdam, J.W.; van Veggel, F.C.J.M.; Driessen, A.

    In the present work we applied a measurement setup to determine several relevant properties of rare-earth doped nanoparticles dispersed in polymer slab waveguides in a single absorption measurement: background absorption of the polymer host material, water absorption, polymer composition

  8. Absorption spectroscopy of complex rare earth ion doped hybrid materials over a broad wavelength range

    NARCIS (Netherlands)

    Dekker, R.; Worhoff, Kerstin; Stouwdam, J.W.; van Veggel, F.C.J.M.; Driessen, A.

    2005-01-01

    In the present work we applied a measurement setup to determine several relevant properties of rare-earth doped nanoparticles dispersed in polymer slab waveguides in a single absorption measurement: background absorption of the polymer host material, water absorption, polymer composition

  9. Kinetics of Rare Earth Extraction from Baotou Bastnaesite in Hydrochloric Acid and Aluminum Chloride

    Science.gov (United States)

    Zhang, Xiao-Wei; Li, Mei; Liu, Zhao-Gang; Hu, Yan-Hong; Wang, Mi-Tang

    2017-10-01

    In this paper, the leaching kinetics of rare earth from Baotou bastnaesite in a HCl-AlCl3 solution was investigated. In addition, the effects of the HCl and AlCl3 concentrations, liquid to solid ratio, stirring speed, temperature, and time spent on the rare earth extraction were determined. The results indicated that the extraction was nearly independent of the stirring speed when it did not exceed 300 rpm, and the rate of leaching increased with increases in the HCl and AlCl3 concentrations, liquid to solid ratio, temperature, and time. The optimum dissolution conditions were determined under five experimental conditions. After leaching occurred, the progressive dissolution of the bastnaesite phase could be determined. The leaching kinetics was analyzed with a new variant of the shrinking core model in which both the interfacial transfer and diffusion across the product layer affected the rare earth extraction. The apparent activation energy was 35.57 kJ/mol, and the Arrhenius constant was 341.58 min-1. An empirical equation was derived to describe the extraction process of rare earth minerals.

  10. 78 FR 42974 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same...

    Science.gov (United States)

    2013-07-18

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same... making same and products containing same by reason of infringement of certain claims of United States...

  11. Magnetic-field-induced valence transition in rare-earth systems

    Indian Academy of Sciences (India)

    loys are induced by pressure, temperature or chemical alloying. The change in the valence state of rare-earth ion is found to be either continuous or discontinuous. One of the com- mon features of all the systems which show valence instabilities is that, in the intermediate valence phase, the system fluctuates between a ...

  12. Rare Earth Elements: Overview of Mining, Mineralogy, Uses, Sustainability and Environmental Impact

    Directory of Open Access Journals (Sweden)

    Nawshad Haque

    2014-10-01

    Full Text Available Rare earths are used in the renewable energy technologies such as wind turbines, batteries, catalysts and electric cars. Current mining, processing and sustainability aspects have been described in this paper. Rare earth availability is undergoing a temporary decline due mainly to quotas being imposed by the Chinese government on export and action taken against illegal mining operations. The reduction in availability coupled with increasing demand has led to increased prices for rare earths. Although the prices have come down recently, this situation is likely to be volatile until material becomes available from new sources or formerly closed mines are reopened. Although the number of identified deposits in the world is close to a thousand, there are only a handful of actual operating mines. Prominent currently operating mines are Bayan Obo in China, Mountain Pass in the US and recently opened Mount Weld in Australia. The major contributor to the total greenhouse gas (GHG footprint of rare earth processing is hydrochloric acid (ca. 38%, followed by steam use (32% and electricity (12%. Life cycle based water and energy consumption is significantly higher compared with other metals.

  13. Influence of Rare Earth Element Supply on Future Offshore Wind Turbine Generators

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Abrahamsen, Asger Bech; Henriksen, Matthew Lee

    2011-01-01

    electrical machines. Such machines are utilized in applications such as electric cars, and wind turbines. This paper will examine the rare earth supply issue, in order to comment on its relevance to the wind turbine industry. The wind turbine topologies which are currently being used are compared...

  14. Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

    Science.gov (United States)

    Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

  15. Exploring Rare Earths supply constraints for the emerging clean energy technologies and the role of recycling

    DEFF Research Database (Denmark)

    Habib, Komal; Wenzel, Henrik

    The dependency on critical resources like Rare Earth Elements (REEs) has been pronounced as a potential barrier to a broader implementation of emerging renewable energy technologies. This study explores the dependency of such technologies especially wind turbines and electric vehicles along...

  16. RARE EARTH ELEMENTS: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES

    Science.gov (United States)

    Rare earth elements (REEs) are a group of 15 chemical elements in the periodic table, specifically the lanthanides. Two other elements, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...

  17. Preliminary study on using rare earth elements to trace non-point source phosphorous loss

    Science.gov (United States)

    The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare earth elements (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential...

  18. Electrodeposition Techniques for the Preparation of Beta-Sprectroscopy Sources of Rare-Earth Elements

    DEFF Research Database (Denmark)

    Hansen, P. Gregers; Høgh, J.; Nielsen, H. L.

    1964-01-01

    Thin, uniform radioactive deposits of rare earths and related elements can be prepared by cathodic electrodeposition of their hydroxides. The main theoretical and experimental features of this process are reviewed and plating cell design and the choice of conditions are described together...

  19. Mixing rare earth elements with manures to control phosphorus loss in runoff and track manure fate

    Science.gov (United States)

    Concern over the enrichment of agricultural runoff with phosphorus (P) from land applied livestock manures has prompted the development of manure amendments that minimize P solubility. We evaluated the effect of mixing two rare earth chlorides, lanthanum chloride and ytterbium chloride, with poultr...

  20. A CONTRIBUTION TO THE RESEARCH ON RARE EARTH ELEMENTS IN SEDIMENTARY ROCKS

    Directory of Open Access Journals (Sweden)

    Josip Crnički

    1989-12-01

    Full Text Available The main features of the geochemistry of rare earth elements (REE, REE mineralogy and the REE i contents and distributions in sedimentary rocks are presented. A new classification of REE minerals as well as a new systematic order of the REE behaviour in sedimentology is introduced and explained.

  1. Technical Information Resource on Rare Earth Elements Now Available to Public and Private Sector Stakeholders

    Science.gov (United States)

    A new EPA technical information resource, “Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues” has been produced as an introductory resource for those interested in learning more about REE mining and alternatives to meet demand...

  2. Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

    Science.gov (United States)

    Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

    2016-08-30

    The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

  3. Correlation of radiative properties of rare earth ions (Pr and Nd ) in ...

    Indian Academy of Sciences (India)

    Unknown

    elements, 'fcal' values are obtained. The experimental spectral intensities for all the transitions of Pr3+ and Nd3+ ions in 0⋅1 and 0⋅5 mol% concentrations of rare earth ion in potassium and lead chlorophosphate glasses are presented in table 3. The rms deviations which show agreement between experimental and ...

  4. Maximum Permissible Concentrations and Negligible Concentrations for Rare Earth Elements (REEs)

    NARCIS (Netherlands)

    Sneller FEC; Kalf DF; Weltje L; Wezel AP van; CSR

    2000-01-01

    In this report maximum permissible concentrations (MPCs) and negligible concentrations (NCs) are derived for Rare Earth Elements (REEs), which are also known as lanthanides. The REEs selected for derivation of environmental risk limits in this report are Yttrium (Y), Lanthanum (La), Cerium (Ce),

  5. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...

  6. When materials become critical : lessons from the 2010 rare earth crisis

    NARCIS (Netherlands)

    Sprecher, B.

    2016-01-01

    This dissertation is the culmination of over four years research on the rare earth element neodymium in the context of the 2010 REE crisis. Neodymium is a generally recognized ‘critical’ material with a relevant application in the form of NdFeB magnets, both for sustainable energy technologies as

  7. Exploring Rare Earths supply constraints for the emerging clean energy technologies and the role of recycling

    DEFF Research Database (Denmark)

    Habib, Komal; Wenzel, Henrik

    2014-01-01

    The dependency on critical resources like Rare Earth Elements (REEs) has been pronounced as a potential barrier to a wider implementation of emerging renewable energy technologies. This study explores the dependency of such technologies especially wind turbines and electric vehicles along...

  8. Page 1 342 Kay R. W. and Gast P W 1973 The rare earth content ...

    Indian Academy of Sciences (India)

    magnesian tholeiites; Earth Planet Sci. Lett. 31 433–453. Nystrom J O 1984 Rare earth element mobility in vesicular lava during low-grade metamorphism; Contrib. Mineral. Petrol. 88 328–331. Pearce J A and Cann J R 1973 Tectomic setting of basic volcanic rocks determined using trace element analyses;. Earth Planel.

  9. Changes in the Concentration of Some Rare Earth Elements in Coal Waste

    Science.gov (United States)

    Nowak, Jacek; Kokowska-Pawłowska, Magdalena

    2017-09-01

    Coal waste is formed during coal mining and processing operations. That waste comprises mainly sedimentary rocks that occur in roofs and floors of underground workings and in partings in coal seams. It contains numerous trace elements, including rare earth elements (REEs). Hypergenic processes that take place in coal waste piles may lead to endogenous fires. Thermal transformations of waste have an effect on changes in its phase and chemical composition, including the concentration of trace elements. The paper presents changes in the content of selected rare earth elements (Sc, Y, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu) in wastes of varying degree of thermal transformation. The results of REE content determination in lump samples were subjected to statistical analysis and coefficients of correlation between the studied rare earth elements and the main chemical constituents were determined. The primary carriers of REEs in coal waste are clay minerals. Phase transformations that take place at high temperatures (including dehydroxylation of clay minerals and formation of minerals characteristic of contact metamorphism) cause changes in the concentration of rare earth elements.

  10. No Giant Two-Ion Anisotropy in the Heavy-Rare-Earth Metals

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A new Bose-operator expansion of tensor operators is applied to the heavy-rare-earth metals. The Er data for the cone phase have been analyzed successfully with single-ion anisotropy and isotropic exchange interaction. The Tb data can be understood on the same basis. The previously found large two...

  11. Vibration spectra of complexes of rare earth nitrate with some Schiff bases

    Science.gov (United States)

    Guofa, Liu

    1994-06-01

    Infrared and Raman spectra of complexes of rare earth nitrate with Schiff bases derived from vanillin (3-methoxy-4-hydroxy-benzaldehyde) or o-vanillin (2-hydroxy-3-methoxy-benzaldehyde) and p-toluidine, 1-naphthylamine, 2-naphthylamine are reported.

  12. Distribution of the rare earth elements in the sediments of the ...

    African Journals Online (AJOL)

    Rare earth elements (REE), define a group of fifteen chemical elements from lanthanum to lutetium (atomic numbers 57-71) characterized by similar chemical properties. To study their distribution in sediment samples of the Bouregreg river and its tributaries, 10 sampling sites have been chosen. The collected sediment ...

  13. Defect structure of cubic solid solutions of alkaline earth and rare earth fluorides

    NARCIS (Netherlands)

    DenHartog, HW

    1996-01-01

    In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the

  14. Reduced molybdenum oxide as an efficient electron injection layer in polymer light-emitting diodes

    Science.gov (United States)

    Vasilopoulou, Maria; Palilis, Leonidas C.; Georgiadou, Dimitra G.; Argitis, Panagiotis; Kennou, Stella; Sygellou, Labrini; Kostis, Ioannis; Papadimitropoulos, Giorgos; Konofaos, Nikos; Iliadis, Agis A.; Davazoglou, Dimitris

    2011-03-01

    We report a significant improvement in the performance of single layer polymer light-emitting diodes (PLEDs), based on the green emitting copolymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2, 1',3}-thiadiazole)], upon inserting a very thin layer of partially reduced molybdenum oxide (MoOx, where x=2.7) at the polymer/Al cathode interface. Both fully oxidized (x=3) and partially reduced (x=2.7) thin molybdenum oxide layers were investigated as electron injection layers and their influence on PLED device performance was examined. Improved current density, luminance, and efficiency was achieved only in the case of devices with a thin partially reduced MoO2.7 film as electron injection layer, as a result of improved electron injection and more facile transfer at the modified polymer/Al interface.

  15. Luminescent polymethacrylate composite nanofibers containing a benzoic acid rare earth complex: Morphology and luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Fulai [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); Xi, Peng, E-mail: xpsyq0007@sina.com [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); State Key laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing (China); Xia, Haiying; Wang, Chaohua; Gao, Li [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China); Cheng, Bowen, E-mail: Bowen@tjpu.edu.cn [Tianjin Municipal Key Lab of Fiber Modification and Functional Fiber, Tianjin Polytechnic University, 300387 Tianjin (China)

    2015-08-25

    Highlights: • We synthesize PMMA composite nanofibers containing benzoic acid rare earth complex. • We investigate the effects of nanofiber morphology on luminescence properties. • Nanofibers with different morphologies had different luminescence characteristics. • Fluorescence intensity and emission lifetime of porous nanobeads were the highest. • Nanofibers with a porous structure showed the stronger fluorescent recognition ability. - Abstract: In this study, we systematically investigated the morphologies and luminescence properties of luminescent polymethacrylate composite nanofibers containing a benzoic acid rare earth complex. The analysis results indicated that the benzoic acid rare earth complex, Tb(4-methylbenzoic acid){sub 3}phen, was distributed uniformly in the polymethacrylate nanofibers, which were fabricated by electrostatic spinning. The Tb(4-methylbenzoic acid){sub 3}phen content in the polymethacrylate nanofibers was as high as 20% (mass%). The emission peaks of the as-prepared polymethacrylate composite nanofibers corresponded to the characteristic {sup 5}D{sub 4}–{sup 7}F{sub 6,5,4,3} transitions of Tb{sup 3+} ions. The highest emission peak was observed at 548 nm and corresponded to the {sup 5}D{sub 4}–{sup 7}F{sub 5} transition. When the Tb(4-methylbenzoic acid){sub 3}phen content was less than 1%, even a 0.2% increase in the content increased the fluorescence intensity markedly. The thermal stability of the rare earth complex was higher in the as-prepared nanofibers; the initial decomposition temperature of the polymethacrylate composite nanofiber reached 291 °C. Composite nanofibers with different morphologies exhibited different luminescence characteristics. The fluorescence intensity and emission lifetime of porous nanobeads were nine and two times higher, respectively, than those of smooth nanofibers. The better morphological and luminescence properties exhibited by the synthesized luminescent polymethacrylate composite

  16. Rare earth metals in North America; Zeldzame aardmetalen in Noord-Amerika

    Energy Technology Data Exchange (ETDEWEB)

    Louzada, K.

    2012-11-15

    The uncertain supply of rare earth metals (Rare Earth Elements) from China for the high tech industry in the U.S. is a barrier for innovation and the high-tech manufacturing industry. Many rare earths are applied in permanent magnets for sustainable energy generation and for energy storage systems in for example electric cars. Also other sectors feel the pressure of shortages. The federal government in the USA and US companies use the opportunity to encourage research into recycling, reducing the use and finding alternatives for rare earths. Canada sees in the uncertain supply and dwindling reserves in the USA and elsewhere an economic opportunity. Canada can start the development of hitherto unprofitable reserves of valuable materials. Both in the USA and Canada, the number of exploration projects in the mining industry has grown significantly [Dutch] De onzekere aanvoer van zeldzame aardmetalen (Rare Earth Elements) uit China voor de hightechindustrie vormt in de VS een hindernis voor innovatie en voor de hightech maakindustrie. Met name in permanente magneten voor duurzame energieopwekking en energieopslagsystemen voor bijvoorbeeld elektrische auto's worden veel zeldzame aardmetalen verwerkt. Ook andere sectoren staan onder druk. De federale overheid en bedrijven in de VS maken van de gelegenheid gebruik om onderzoek naar de recycling, vermindering van het gebruik en alternatieven voor zeldzame aardmetalen te stimuleren. Canada ziet de onzekere aanvoer en slinkende reserves in de VS en elders als een economische kans. Het land kan tot nu toe onrendabele voorkomens van de waardevolle materialen gaan ontwikkelen. Zowel in de VS als in Canada is het aantal exploratieprojecten in de mijnbouw aanzienlijk gegroeid.

  17. Photo-luminescent properties of a green or red emitting Tb3+ or Eu3+ doped calcium magnesium silicate phosphors

    Science.gov (United States)

    Onani, Martin O.; Dejene, Francis B.

    2014-04-01

    This study describes green-emitting Tb3+ or red-emitting Eu3+ doped calcium magnesium silicate phosphors by ultraviolet excitation at 335 nm. The rare earth activated amorphous calcium silicate was prepared by a solution-combustion process at 600 °C for 5-10 min. The Ca2MgSi2O7 prepared using urea and ammonium nitrate has a tetragonal crystal structure. The resulting Tb3+-doped phosphor emitted green light centered at 544 nm. The optimum excitation wavelength within the range 300-400 nm was 335 nm. The intensity and emitting wavelength of the Eu3+ doped samples can be controlled by annealing in a reducing or oxidizing environment, allowing light to be emitted as green or red. When the reducing environment is optimized, the emission spectrum of Ca2MgSi2O7:Eu2+ is a broad band at 497 nm.

  18. Rare-earth elements in the Permian Phosphoria Formation: Paleo proxies of ocean geochemistry

    Science.gov (United States)

    Piper, D.Z.; Perkins, R.B.; Rowe, H.D.

    2007-01-01

    The geochemistry of deposition of the Meade Peak Member of the Phosphoria Formation (MPM) in southeast Idaho, USA, a world-class sedimentary phosphate deposit of Permian age that extends over 300,000 km2, is ascertained from its rare earth element (REE) composition. Ratios of REE:Al2O3 suggest two sources-seawater and terrigenous debris. The seawater-derived marine fraction identifies bottom water in the Phosphoria Sea as O2-depleted, denitrifying (suboxic) most of the time, and seldom sulfate-reducing (anoxic). This interpretation is supported by earlier research that showed progressively greater ratios in the marine sediment fraction of Cr:Ni>V:Ni???Mo:Ni, relative to their ratios in seawater; for which marine Cr, V, and Mo can have a dominantly O2-depleted bottom-water source and Ni a photic-zone, largely algal, source. The water chemistry was maintained by a balance between bacterial oxidation of organic matter settling through the water column, determined largely by primary productivity in the photic zone, and the flux of oxidants into the bottom water via advection of seawater from the open ocean. Samples strongly enriched in carbonate fluorapatite, the dominant REE host mineral, have variable Er/Sm, Tm/Sm, and Yb/Sm ratios. Their distribution may represent greater advection of seawater between the Phosphoria Sea and open ocean during deposition of two ore zones than a center waste and greater upwelling of nutrient-enriched water into the photic zone. However, the mean rate of deposition of marine Ni, a trace nutrient of algae, and PO43-, a limiting nutrient, indicate that primary productivity was probably high throughout the depositional history. An alternative interpretation of the variable enrichments of Er, Tm, and Yb, relative to Sm, is that they may reflect temporally variable carbonate alkalinity of open-ocean seawater in Permian time. A more strongly negative Ce anomaly for all phosphatic units than the Ce anomaly of modern pelletal phosphate is

  19. Rare earth elements upon assessment of reasons of the geophagy in Sikhote-Alin region (Russian Federation), Africa and other world regions.

    Science.gov (United States)

    Panichev, Alexander M; Popov, Vladimir K; Chekryzhov, Igor Yu; Seryodkin, Ivan V; Stolyarova, Tatiana A; Zakusin, Sergey V; Sergievich, Alexandr A; Khoroshikh, Pavel P

    2016-12-01

    Rocks eaten by wild animals on the Bolshoy Shanduyskiy kudur in the Sikhote-Alin region (Russian Federation) are zeolite-clay mineral complexes-products of weathering of zeolitized vitric tuffs of rhyolite composition, deposited in aqueous medium within the volcanic caldera of about 55 million years ago. By composition of rock-forming oxides, the tuffs refer to high-potassium calc-alkaline series. In trace elements of most favorite kudurites of the Bolshoy Shanduyskiy kudur, there are significantly increased contents of most of rare earth elements (2-5 times in comparison with surrounding rocks). The results of our analysis of geological and geochemical data on kudurs and kudurites in another part of the Sikhote-Alin, as well as on other regions of the world (particularly, in Africa and Indonesia), taking into account new data on the prevalence of rare earth elements in living matter and their medical and biological properties, enable us to consider the version of causal connection of the geophagy with rare earth elements.

  20. Preliminary estimates of the quantities of rare-earth elements contained in selected products and in imports of semimanufactured products to the United States, 2010

    Science.gov (United States)

    Bleiwas, Donald I.; Gambogi, Joseph

    2013-01-01

    Rare-earth elements (REEs) are contained in a wide range of products of economic and strategic importance to the Nation. The REEs may or may not represent a significant component of that product by mass, value, or volume; however, in many cases, the embedded REEs are critical for the device’s function. Domestic sources of primary supply and the manufacturing facilities to produce products are inadequate to meet U.S. requirements; therefore, a significant percentage of the supply of REEs and the products that contain them are imported to the United States. In 2011, mines in China produced roughly 97 percent of the world’s supply of REEs, and the country’s production of these elements will likely dominate global supply until at least 2020. Preliminary estimates of the types and amount of rare-earth elements, reported as oxides, in semimanufactured form and the amounts used for electric vehicle batteries, catalytic converters, computers, and other applications were developed to provide a perspective on the Nation’s use of these elements. The amount of rare-earth metals recovered from recycling, remanufacturing, and reuse is negligible when the tonnage of products that contain REEs deposited in landfills and retained in storage is considered. Under favorable market conditions, the recovery of REEs from obsolete products could potentially displace a portion of the supply from primary sources.

  1. Antiferromagnetic transitions of osmium-containing rare earth double perovskites Ba{sub 2}LnOsO{sub 6} (Ln=rare earths)

    Energy Technology Data Exchange (ETDEWEB)

    Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp; Doi, Yoshihiro; Wakeshima, Makoto

    2013-10-15

    The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Os{sup 5+} ions are structurally ordered at the M site of the perovskite BaMO{sub 3}. Magnetic susceptibility and specific heat measurements show that an antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Magnetic ordering of Ln{sup 3+} moments occurs when the temperature is furthermore decreased. - Graphical abstract: The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. An antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Measurements and analysis of the specific heat for Ba{sub 2}PrOsO{sub 6} show that magnetic ordering of the Pr{sup 3+} moments should have occurred at ∼20 K. Display Omitted.

  2. 75 FR 25293 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Rare Earth...

    Science.gov (United States)

    2010-05-07

    ... Earth Industry and Technology Association Notice is hereby given that, on March 22, 2010, pursuant to.... (``the Act''), the Rare Earth Technology Consortium (``RETC'') has filed written notifications... to the venture are: Rare Earth Industry and Tecimology Association, Greenwood Village, CO; Global...

  3. High index contrast potassium double tungstate waveguides towards efficient rare-earth ion amplification on-chip

    NARCIS (Netherlands)

    Sefünç, Mustafa; Segerink, Franciscus B.; García Blanco, Sonia Maria

    2015-01-01

    Rare-earth ion doped KY(WO4)2 amplifiers are proposed to be a good candidate for many future applications by benefiting from the excellent gain characteristics of rare-earth ions, namely high bit rate amplification (

  4. Signatures of rare-earth elements in banded corals of Kalpeni atoll-Lakshadweep archipelago in response to monsoonal variations

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.A.S.; Nath, B.N.; Balaram, V.

    occurred with REE and the light rare-earths (LREE) enriched in the high density (representing monsoon season) bands. In contrast, the heavy rare-earths (HREE) are enriched in the low density bands. LREE enrichment in the high density bands is attributed...

  5. From mantle to critical zone: A review of large and giant sized deposits of the rare earth elements

    Directory of Open Access Journals (Sweden)

    M.P. Smith

    2016-05-01

    Full Text Available The rare earth elements are unusual when defining giant-sized ore deposits, as resources are often quoted as total rare earth oxide, but the importance of a deposit may be related to the grade for individual, or a limited group of the elements. Taking the total REE resource, only one currently known deposit (Bayan Obo would class as giant (>1.7 × 107 tonnes contained metal, but a range of others classify as large (>1.7 × 106 tonnes. With the exception of unclassified resource estimates from the Olympic Dam IOCG deposit, all of these deposits are related to alkaline igneous activity – either carbonatites or agpaitic nepheline syenites. The total resource in these deposits must relate to the scale of the primary igneous source, but the grade is a complex function of igneous source, magmatic crystallisation, hydrothermal modification and supergene enrichment during weathering. Isotopic data suggest that the sources conducive to the formation of large REE deposits are developed in subcontinental lithospheric mantle, enriched in trace elements either by plume activity, or by previous subduction. The reactivation of such enriched mantle domains in relatively restricted geographical areas may have played a role in the formation of some of the largest deposits (e.g. Bayan Obo. Hydrothermal activity involving fluids from magmatic to meteoric sources may result in the redistribution of the REE and increases in grade, depending on primary mineralogy and the availability of ligands. Weathering and supergene enrichment of carbonatite has played a role in the formation of the highest grade deposits at Mount Weld (Australia and Tomtor (Russia. For the individual REE with the current highest economic value (Nd and the HREE, the boundaries for the large and giant size classes are two orders of magnitude lower, and deposits enriched in these metals (agpaitic systems, ion absorption deposits may have significant economic impact in the near future.

  6. Understanding rhizosphere processes to enhance phytoextraction of germanium and rare earth elements

    Science.gov (United States)

    Wiche, Oliver

    2017-04-01

    Germanium (Ge) and rare earth elements (REEs) are economically valuable raw materials that are not actually rare in terms of concentrations in soils but they are hardly available for plant uptake due to interactions with organic matter (SOM), secondary soil constituents such as Fe/Mn oxides and P bearing soil fractions. Processes in the rhizosphere might influence availability of Ge and REEs in the soil-plant system, since lowering of the pH and presence of carboxylates and siderophores (small molecules that strongly chelate Fe and other elements) strongly influences the chemical speciation of Ge and REEs in soil and consequently this comprehensive knowledge helps us to improve phytomining. In a series of field and greenhouse experiments 16 plant species from the functional groups of grasses, herbs and legumes were tested with regard to their accumulation efficiency of Ge and REEs in shoots. Subsequently, we conducted mixed culture experiments in which inefficient species (e.g. cereals like Avena sativa, Hordeum vulgare, Panicum miliaceum) were cultivated in mixed cultures with efficient species (Lupinus albus, Lupinus angustifolius). Based on the plant concentrations a principal component analysis (PCA) was performed to identify significant factors that explain the accumulation behavior of different plant species with regard to Ge, REEs, Si, Fe and Mn. In this analysis Mn was used to identify plant species with efficient mechanisms to access sparingly available P-resources in soils. Particularly in nonmycorrhizal species concentrations of Mn in leaves often indicate a carboxylate based P-mobilising strategy. Herbaceous plant species accumulated significantly higher amounts of REEs while grasses accumulated significantly higher amounts of Ge. Concentrations of Ge in shoots of grasses correlated significantly positive with Si, but negatively with concentrations of Mn. Indeed, the results of the PCA clearly show that plants with high Mn concentrations tend to have

  7. Typical aqueous rare earth element behavior in co-produced Brines, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Nye, Charles; Quillinan, Scott [UNIVERSIty of Wyoming; McLing, Travis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neupane, Ghanashyam [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-10-24

    Normalization of Rare Earth Elements (REEs) is important to remove the distracting effects of the Oddo–Harkins rule and provide a meaningful baseline. Normalizations for rocks are well developed and include chondritic meteorites, UCC, PM, PAAS, and NASC. However normalizations for aqueous REEs are limited to oceanic regions such as the North Pacific Deep Water or North Atlantic Surface Water. This leaves water in contact with continental lithologies without a suitable normalization. We present a preliminary continental aqueous REE normalization derived from 38 deep basin hydrocarbon brines in Wyoming. The REEs in these waters are seven orders of magnitude more dilute than NASC but with significant europium enrichment. Gromet 1984 reports NASC Eu/Eu* is 0.2179, whereas in the normalization offered here, Eu/Eu* is 3.868. These waters also are free from the distracting reduction-oxidation cerium behavior found in ocean normalizations. Because these samples exhibit both the uniform behavior of NASC and the absolute concentration of seawater, a normalization based upon them offers a unique combination of the advantages of both. We used single-peak gaussian analysis to quantify the mean values for each REE and estimate the distribution variability. Additional sample collection during the last year revealed that the Powder River Basin (PRB) is atypical relative to the other sampled basins of Wyoming. Those other basins are the Wind River Basin (WRB) Green River Basin (GRB) and Wamsutter Area (WA). A pre-normalization gadolinium anomaly (Gd/Gd*) of between 4 and 23 with a mean of 11.5, defines the PRB samples. Other basins in this study range from 1 to 7 with a mean of 2.8. Finally, we present a preliminary model for ligand-based behavior of REEs in these samples. This model identifies bicarbonate, bromide, and chloride as forming significant complexes with REEs contributing to REE solubility. The ligand model explains observed REEs in the sampled Cretaceous and

  8. Rare Earth Element Measurements of Melilite and Fassaite in Allende Cai by Nanosims

    Science.gov (United States)

    Ito, M.; Messenger, Scott

    2009-01-01

    The rare earth elements (REEs) are concentrated in CAIs by approx. 20 times the chondritic average [e.g., 1]. The REEs in CAIs are important to understand processes of CAI formation including the role of volatilization, condensation, and fractional crystallization [1,2]. REE measurements are a well established application of ion microprobes [e.g., 3]. However the spatial resolution of REE measurements by ion microprobe (approx.20 m) is not adequate to resolve heterogeneous distributions of REEs among/within minerals. We have developed methods for measuring REE with the NanoSIMS 50L at smaller spatial scales. Here we present our initial measurements of REEs in melilite and fassaite in an Allende Type-A CAI with the JSC NanoSIMS 50L. We found that the key parameters for accurate REE abundance measurements differ between the NanoSIMS and conventional SIMS, in particular the oxide-to-element ratios, the relative sensitivity factors, the energy distributions, and requisite energy offset. Our REE abundance measurements of the 100 ppm REE diopside glass standards yielded good reproducibility and accuracy, 0.5-2.5 % and 5-25 %, respectively. We determined abundances and spatial distributions of REEs in core and rim within single crystals of fassaite, and adjacent melilite with 5-10 m spatial resolution. The REE abundances in fassaite core and rim are 20-100 times CI abundance but show a large negative Eu anomaly, exhibiting a well-defined Group III pattern. This is consistent with previous work [4]. On the other hand, adjacent melilite shows modified Group II pattern with no strong depletions of Eu and Yb, and no Tm positive anomaly. REE abundances (2-10 x CI) were lower than that of fassaite. These patterns suggest that fassaite crystallized first followed by a crystallization of melilite from the residual melt. In future work, we will carry out a correlated study of O and Mg isotopes and REEs of the CAI in order to better understand the nature and timescales of its

  9. Concentrations and health risk assessment of rare earth elements in vegetables from mining area in Shandong, China.

    Science.gov (United States)

    Zhuang, Maoqiang; Zhao, Jinshan; Li, Suyun; Liu, Danru; Wang, Kebo; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhou, Jingyang; Wang, Liansen; Chu, Zunhua

    2017-02-01

    To investigate the concentrations of rare earth elements in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare earth elements in vegetables from mining and control areas were 94.08 μg kg-1 and 38.67 μg kg-1, respectively, and the difference was statistically significant (p rare earth elements concentration (984.24 μg kg-1 and 81.24 μg kg-1 for mining and control areas, respectively) and gourd vegetable had the lowest rare earth elements concentration (37.34 μg kg-1 and 24.63 μg kg-1 for mining and control areas, respectively). For both areas, the rare earth elements concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg-1 d-1 and 0.28 μg kg-1 d-1 for mining and control areas, respectively) of rare earth elements through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg-1 d-1). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare earth elements on children. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kamiya, Noriho [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Goto, Masahiro, E-mail: m-goto@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2013-06-15

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

  11. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    Science.gov (United States)

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  12. Electronic and Magnetic Properties of Rare-Earth Metals Doped ZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan

    2015-01-01

    Full Text Available The structural, electronic, and magnetic properties of rare-earth metals doped ZnO monolayer have been investigated using the first-principles calculations. The induced spin polarization is confirmed for Ce, Eu, Gd, and Dy dopings while the induced spin polarization is negligible for Y doping. The localized f states of rare-earth atoms respond to the introduction of a magnetic moment. ZnO monolayer undergoes transition from semiconductor to metal in the presence of Y, Ce, Gd, and Dy doping. More interestingly, Eu doped ZnO monolayer exhibits half-metallic behavior. Our result demonstrates that the RE-doping is an efficient route to modify the magnetic and electronic properties in ZnO monolayer.

  13. Results from the nuclear microprobe PIXE analysis of selected rare earth fluor compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hollerman, William A. E-mail: hollerman@louisiana.edu; Gates, Earl; Boudreaux, Philip; Glass, Gary A

    2002-04-01

    Most previous research measures fluorescence properties over the macroscopic regime. Properties of individual microscopic grains could be significantly different than those measured over the macroscopic scale. Until recently, it was difficult to measure properties of individual fluor grains. Existing characterization techniques like scanning electron microscopy are not practical, since the resulting fluorescence masks the electron surface profile. Starting in September 2000, a research program was initiated at the Acadiana Research Laboratory to determine microscopic fluorescence properties for selected inorganic rare earth compounds. The initial phase of this program utilized microscopic proton induced X-ray emission ({mu}PIXE) to characterize the elemental composition of individual fluor grains. Results show that both individual grains and small clusters of grains could be seen using {mu}PIXE. Maps of this type can be used to estimate grain dimensions for the selected rare earth fluor. This technique is a new and innovative method to characterize a fluor material.

  14. Results from the nuclear microprobe PIXE analysis of selected rare earth fluor compounds

    Science.gov (United States)

    Hollerman, William A.; Gates, Earl; Boudreaux, Philip; Glass, Gary A.

    2002-04-01

    Most previous research measures fluorescence properties over the macroscopic regime. Properties of individual microscopic grains could be significantly different than those measured over the macroscopic scale. Until recently, it was difficult to measure properties of individual fluor grains. Existing characterization techniques like scanning electron microscopy are not practical, since the resulting fluorescence masks the electron surface profile. Starting in September 2000, a research program was initiated at the Acadiana Research Laboratory to determine microscopic fluorescence properties for selected inorganic rare earth compounds. The initial phase of this program utilized microscopic proton induced X-ray emission (μPIXE) to characterize the elemental composition of individual fluor grains. Results show that both individual grains and small clusters of grains could be seen using μPIXE. Maps of this type can be used to estimate grain dimensions for the selected rare earth fluor. This technique is a new and innovative method to characterize a fluor material.

  15. High quality factor nanophotonic resonators in bulk rare-earth doped crystals

    CERN Document Server

    Zhong, Tian; Kindem, Jonathan M; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Numerous bulk crystalline materials exhibit attractive nonlinear and luminescent properties for classical and quantum optical applications. A chip-scale platform for high quality factor optical nanocavities in these materials will enable new optoelectronic devices and quantum light-matter interfaces. In this article, photonic crystal nanobeam resonators fabricated using focused ion beam milling in bulk insulators, such as rare-earth doped yttrium orthosilicate and yttrium vanadate, are demonstrated. Operation in the visible, near infrared, and telecom wavelengths with quality factors up to 27,000 and optical mode volumes close to one cubic wavelength is measured. These devices enable new nanolasers, on-chip quantum optical memories, single photon sources, and non-linear devices at low photon numbers based on rare-earth ions. The techniques are also applicable to other luminescent centers and crystals.

  16. Realizing the therapeutic potential of rare earth elements in designing nanoparticles to target and treat glioblastoma.

    Science.gov (United States)

    Lu, Victor M; McDonald, Kerrie L; Townley, Helen E

    2017-10-01

    The prognosis of brain cancer glioblastoma (GBM) is poor, and despite intense research, there have been no significant improvements within the last decade. This stasis implicates the need for more novel therapeutic investigation. One such option is the use of nanoparticles (NPs), which can be beneficial due to their ability to penetrate the brain, overcome the blood-brain barrier and take advantage of the enhanced permeation and retention effect of GBM to improve specificity. Rare earth elements possess a number of interesting natural properties due to their unique electronic configuration, which may prove therapeutically advantageous in an NP formulation. The underexplored exciting potential for rare earth elements to augment the therapeutic potential of NPs in GBM treatment is discussed in this review.

  17. Crystal-field investigations of rare-earth-doped wide band gap semiconductors

    CERN Multimedia

    Muller, S; Wahl, U

    Crystal field investigations play a central role in the studies of rare earth doped semiconductors. Optical stark level spectroscopy and lattice location studies of radioactive rare earth isotopes implanted at ISOLDE have provided important insight into these systems during the last years. It has been shown that despite a major site preference of the probe atoms in the lattice, several defect configurations do exist. These sites are visible in the optical spectra but their origin and nature aren't deducible from these spectra alone. Hyperfine measurements on the other hand should reveal these defect configurations and yield the parameters necessary for a description of the optical properties at the atomic scale. In order to study the crystal field with this alternative approach, we propose a new concept for perturbed $\\gamma\\gamma$-angular correlation (PAC) experiments at ISOLDE based on digital signal processing in contrast to earlier analog setups. The general functionality of the spectrometer is explained ...

  18. Current status and recent topics of rare-earth permanent magnets

    Science.gov (United States)

    Sugimoto, S.

    2011-02-01

    After the development of Nd-Fe-B magnets, rare-earth magnets are now essential components in many fields of technology, because of their ability to provide a strong magnetic flux. There are two, well-established techniques for the manufacture of rare earth magnets: powder metallurgy is used to obtain high-performance, anisotropic, fully dense magnet bodies; and the melt-spinning or HDDR (hydrogenation, disproportionation, desorption and recombination) process is widely used to produce magnet powders for bonded magnets. In the industry of sintered Nd-Fe-B magnets, the total amount of production has increased and their dominant application has been changed to motors. In particular, their use for motors in hybrid cars is one of the most attractive applications. Bonded magnets have also been used for small motors, and the studies of nanocomposite and Sm-Fe-N magnets have become widespread. This paper reviews the current status and future trend in the research of permanent magnets.

  19. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D., E-mail: gbeach@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-06-06

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  20. Multi-Color Luminescence and Sensing of Rare Earth Hybrids by Ionic Exchange Modification.

    Science.gov (United States)

    Weng, Han; Yan, Bing

    2016-07-01

    Luminescent rare earth coordination polymers [H2NMe2]3[Y(DPA)3] ([H2NMe2](+) = dimethyl amino cation; H2DPA = 2,6-dipicolinic acid) are synthesized and is further modified by the ionic exchange reaction of [H2NMe2](+) cation with rare earth ions, which is named as RE(3+) ⊂ [Y(DPA)3] (RE = Eu, Tb, Sm, Dy) hybrid systems. The multi-color can be tuned for these functionalized hybrid systems and even white color luminescence can be integrated for Sm(3+) ⊂ [Y(DPA)3]. Besides, the fluorescent sensing property of Tb(3+) ⊂ [Y(DPA)3] system is checked, which shows high selectivity towards Cr(3+) with the concentration of 10(-5) mol⋅L(-1).