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Sample records for earth metal trihalides

  1. Alkaline earth metal thioindates

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov-Ehmin, B.N.; Ivlieva, V.I.; Filatenko, L.A.; Zajtsev, B.E.; Kaziev, G.Z.; Sarabiya, M.G.

    1984-08-01

    Alkaline earth metal thioindates of MIn/sub 2/S/sub 4/ composition were synthesized by interaction of alkaline earth metal oxoindates with hydrogen sulfide during heating. Investigation into the compounds by X-ray analysis showed that calcium compound crystallizes in cubic crystal system and strontium and barium compounds in rhombic crystal system. Lattice parameters and the number of formula units were determined. Thioindates of M/sub 3/In/sub 2/S/sub 6/ composition were synthesized, their individuality was shown.

  2. Spintronics of Organometal Trihalide Perovskites

    OpenAIRE

    Sun, Dali; Zhang, Chuang; Kavand, Marzieh; van Schooten, Kipp J.; Malissa, Hans; Groesbeck, Matthew; McLaughlin, Ryan; Boehme, Christoph; Vardeny, Z. Valy

    2016-01-01

    The family of organometal trihalide perovskite (OTP), CH3NH3PbX3 (where X is halogen) has recently revolutionized the photovoltaics field and shows promise in a variety of optoelectronic applications. The characteristic spin properties of charge and neutral excitations in OTPs are influenced by the large spin-orbit coupling of the Pb atoms, which may lead to spin-based device applications. Here we report the first studies of pure spin-current and spin-aligned carrier injection in OTP spintron...

  3. Oligomeric rare-earth metal cluster complexes with endohedral transition metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Simon; Zimmermann, Sina; Brühmann, Matthias; Meyer, Eva; Rustige, Christian; Wolberg, Marike; Daub, Kathrin; Bell, Thomas; Meyer, Gerd, E-mail: gerd.meyer@uni-koeln.de

    2014-11-15

    Comproportionation reactions of rare-earth metal trihalides (RX{sub 3}) with the respective rare-earth metals (R) and transition metals (T) led to the formation of 22 oligomeric R cluster halides encapsulating T, in 19 cases for the first time. The structures of these compounds were determined by single-crystal X-ray diffraction and are composed of trimers ((T{sub 3}R{sub 11})X{sub 15}-type, P6{sub 3}/m), tetramers ((T{sub 4}R{sub 16})X{sub 28}(R{sub 4}) (P-43m), (T{sub 4}R{sub 16})X{sub 20} (P4{sub 2}/nnm), (T{sub 4}R{sub 16})X{sub 24}(RX{sub 3}){sub 4} (I4{sub 1}/a) and (T{sub 4}R{sub 16})X{sub 23} (C2/m) types of structure) and pentamers ((Ru{sub 5}La{sub 14}){sub 2}Br{sub 39}, Cc) of (TR{sub r}){sub n} (n=2–5) clusters. These oligomers are further enveloped by inner (X{sup i}) as well as outer (X{sup a}) halido ligands, which possess diverse functionalities and interconnect like oligomers through i–i, i–a and/or a–i bridges. The general features of the crystal structures for these new compounds are discussed and compared to literature entries as well as different structure types with oligomeric T centered R clusters. Dimers and tetramers originating from the aggregation of (TR{sub 6}) octahedra via common edges are more frequent than trimers and pentamers, in which the (TR{sub r}) clusters share common faces. - Graphical abstract: Rare earth-metal cluster complexes with endohedral transition metal atoms (TR{sub 6}) may connect via common edges or faces to form dimers, trimers, tetramers and pentamers of which the tetramers are the most prolific. Packing effects and electron counts play an important role. - Highlights: • Rare-earth metal cluster complexes encapsulate transition metal atoms. • Oligomers are built via connection of octahedral clusters via common edges or faces. • Dimers through pentamers with closed structures are known. • Tetramers including a tetrahedron of endohedral atoms are the most prolific.

  4. 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.

  5. Recovering heavy rare earth metals from magnet scrap

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Alkali metal and alkali earth metal gadolinium halide scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  7. Some Rare Earth Metallic Organohydrides with Biindenyl as the Ligand

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Introduction It is well known that organometallic hydrides of rare earth metals are the catalysts and reducing reagents for the catalysis polymerization of alkenes and the catalysis hydrogenation of alkenoalkynes. There are four methods for the syntheses of organometallic hydrides of rare earth metals: (1) the thermal atomization of metals, I. E. , the interaction of a rare earth metal with alkenes with a terminal alkyne; (2) the Ln-C σ bond is broken with H2; (3) metallic hydride replacement[1], I. E., NaBH4, LiA1H4 and Na can be used to react with organometallic compounds of rare earth metals; (4) the elimination ofβ-H, I. E. , in the presence of LiC1, the elimination of theβ-H of the alkyl compounds of rare earth metals gives the target product. The organohydrides of biindenyl samarium, biindenyl gadolinium and biin denyl dysprosium were obtained with NaH reduction method.

  8. Global Earthing Systems: Characterization of Buried Metallic Parts

    OpenAIRE

    Tommasini, Riccardo; Colella, Pietro; Pons, Enrico

    2016-01-01

    International Standards IEC 61936-1 and EN 50522 define a Global Earthing System (GES) as the earthing network, created by the interconnection of local earthing systems, that should guarantee the absence of dangerous touch voltages. This is achieved through two effects: the division of the earth fault current between many earthing systems and the creation of a quasi equipotential surface. The second effect can be enhanced by the presence of buried metallic parts, such as light poles and water...

  9. Gyroscopic g factor of rare earth metals

    Science.gov (United States)

    Ogata, Y.; Chudo, H.; Ono, M.; Harii, K.; Matsuo, M.; Maekawa, S.; Saitoh, E.

    2017-02-01

    We develop the in situ magnetization measurement apparatus for observing the Barnett effect consisting of a fluxgate sensor, a high speed rotor with frequencies of up to 1.5 kHz, and a magnetic shield at room temperature. The effective magnetic field (Barnett field) in a sample arising from rotation magnetizes the sample and is proportional to the rotational frequency. The gyroscopic g factor, g ' , of rare earth metals, in particular, Gd, Tb, and Dy, was estimated to be 2.00 ± 0.08, 1.53 ± 0.17, and 1.15 ± 0.32, respectively, from the slopes of the rotation dependence of the Barnett field. This study provides a technique to determine the g ' factor even in samples where the spectroscopic method may not be available.

  10. Exciton localization in solution-processed organolead trihalide perovskites

    OpenAIRE

    He, Haiping; Yu, Qianqian; LI, Hui; Li, Jing; Si, Junjie; Jin, Yizheng; Wang, Nana; Wang, Jianpu; He, Jingwen; Wang, Xinke; Zhang, Yan; Ye, Zhizhen

    2016-01-01

    Organolead trihalide perovskites have attracted great attention due to the stunning advances in both photovoltaic and light-emitting devices. However, the photophysical properties, especially the recombination dynamics of photogenerated carriers, of this class of materials are controversial. Here we report that under an excitation level close to the working regime of solar cells, the recombination of photogenerated carriers in solution-processed methylammonium–lead–halide films is dominated b...

  11. Solvent Extraction of Alkaline Earth Metals with Alkylphosphorus Acids

    Institute of Scientific and Technical Information of China (English)

    XUXin; ZHUTun

    2002-01-01

    Solvent extraction equiliria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester, di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent of the e/r value and hydration energy of the metal ions. The minor shift of the P→O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P→O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compunds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effects is explained by using IR spectra of the loaded organic phase.

  12. Method for treating rare earth-transition metal scrap

    Science.gov (United States)

    Schmidt, Frederick A.; Peterson, David T.; Wheelock, John T.; Jones, Lawrence L.

    1992-12-29

    Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

  13. Large gem diamonds from metallic liquid in Earth's deep mantle.

    Science.gov (United States)

    Smith, Evan M; Shirey, Steven B; Nestola, Fabrizio; Bullock, Emma S; Wang, Jianhua; Richardson, Stephen H; Wang, Wuyi

    2016-12-16

    The redox state of Earth's convecting mantle, masked by the lithospheric plates and basaltic magmatism of plate tectonics, is a key unknown in the evolutionary history of our planet. Here we report that large, exceptional gem diamonds like the Cullinan, Constellation, and Koh-i-Noor carry direct evidence of crystallization from a redox-sensitive metallic liquid phase in the deep mantle. These sublithospheric diamonds contain inclusions of solidified iron-nickel-carbon-sulfur melt, accompanied by a thin fluid layer of methane ± hydrogen, and sometimes majoritic garnet or former calcium silicate perovskite. The metal-dominated mineral assemblages and reduced volatiles in large gem diamonds indicate formation under metal-saturated conditions. We verify previous predictions that Earth has highly reducing deep mantle regions capable of precipitating a metallic iron phase that contains dissolved carbon and hydrogen.

  14. 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 ...

  15. Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates

    National Research Council Canada - National Science Library

    Docampo, Pablo; Ball, James M; Darwich, Mariam; Eperon, Giles E; Snaith, Henry J

    2013-01-01

    .... We demonstrate that a single thin film of the low-temperature solution-processed organometal trihalide perovskite absorber CH3NH3PbI3-xClx, sandwiched between organic contacts can exhibit devices...

  16. Recovery of rare earth metals through biosorption:An overview

    Institute of Scientific and Technical Information of China (English)

    Nilanjana Das; Devlina Das

    2013-01-01

    Rare earth metals (REMs) are a series of 17 elements that have widespread and unique applications in high technology, power generation, communications, and defense industries. These resources are also pivotal to emergent sustainable energy and car-bon alternative technologies. Recovery of REMs is interesting due to its high market prices along with various industrial applications. Conventional technologies, viz. precipitation, filtration, liquid-liquid extraction, solid-liquid extraction, ion exchange, super critical extraction, electrowinning, electrorefining, electroslag refining, etc., which have been developed for the recovery of REMs, are not economically attractive. Biosorption represents a biotechnological innovation as well as a cost effective excellent tool for the recovery of rare earth metals from aqueous solutions. A variety of biomaterials such as algae, fungi, bacteria, resin, activated carbon, etc., have been reported to serve as potential adsorbents for the recovery of REMs. The metal binding mechanisms, as well as the parameters in-fluencing the uptake of rare earth metals and isotherm modeling are presented here. This article provides an overview of past achievements and current scenario of the biosorption studies carried out using some promising biosorbents which could serve as an economical means for recovering REMs. The experimental findings reported by different workers will provide insights into this re-search frontier.

  17. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes

    Science.gov (United States)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-08-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  18. Solution thermodynamics of rare-earth metal ions - physicochemical study-

    Energy Technology Data Exchange (ETDEWEB)

    Amerkhanova, Sh K; Shlyapov, R M; Uali, A S [Buketov Karaganda state university, University str., 28, Karaganda, 100028 (Kazakhstan)], E-mail: amerkhanova_sh@mail.ru

    2009-02-01

    The results of the studying of interactions in multicomponent systems 'polyvinyl alcohol (PVA) - rare-earth element ion - nitrate of sodium - water' are represented. It is established that for rubidium (I) ions temperature and ionic strength is render destroying action, and for yttrium (III) ions the influence of these factors has return character which is connected with features of an electronic structure of metal ion. It is revealed that a dominating role of non-electrostatic formation composed, hence, the formation of donor-acceptor connection of 'metal - ligand' occurs through atom of oxygen.

  19. Luminescence enhancement of rare earth ions by metal nanostructures

    Institute of Scientific and Technical Information of China (English)

    G.A.Denisenko

    2009-01-01

    Well-ordered metal structures,i.e.arrays of nanosized tips on silver surface for studies of the luminescence enhancement of absorbed media with rare earth ions were used.These arrays were prepared by the metal evaporation on track membranes.Calculations of resonance frequencies of tips regarded as semispheroids were done taking into account the interaction between dipoles of tips.They were used to discuss experimental results for media with Eu(NO3)3·6H2O salt basing on data for bulk silver dielectric function.

  20. 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...... qualitatively in terms of the relativistic augmented-plane-wave calculations by Keeton and Loucks. The angular distributions in the c direction in the paramagnetic phases are characterized by a rapid drop at low angles followed by a hump, and these features are associated with rather flat regions of Fermi...

  1. Isotopic fractionation of alkali earth metals during carbonate precipitation

    Science.gov (United States)

    Yotsuya, T.; Ohno, T.; Muramatsu, Y.; Shimoda, G.; Goto, K. T.

    2014-12-01

    The alkaline earth metals such as magnesium, calcium and strontium play an important role in a variety of geochemical and biological processes. The element ratios (Mg/Ca and Sr/Ca) in marine carbonates have been used as proxies for reconstruction of the past environment. Recently several studies suggested that the study for the isotopic fractionation of the alkaline earth metals in marine carbonates has a potentially significant influence in geochemical research fields (e.g. Eisenhauer et al., 2009). The aim of this study is to explore the influence of carbonate polymorphs (Calcite and Aragonite) and environmental factors (e.g., temperature, precipitation rate) on the level of isotopic fractionation of the alkaline earth metals. We also examined possible correlations between the level of isotopic fractionation of Ca and that of other alkaline earth metals during carbonate precipitation. In order to determine the isotope fractionation factor of Mg, Ca and Sr during carbonate precipitation, calcite and aragonite were synthesized from calcium bicarbonate solution in which the amount of magnesium was controlled based on Kitano method. Calcium carbonates were also prepared from the mixture of calcium chlorite and sodium hydrogen carbonate solutions. The isotope fractionation factors were measured by MC-ICPMS. Results suggested that the level of isotopic fractionation of Mg during carbonate precipitation was correlated with that of Sr and that the change of the carbonate crystal structure could make differences of isotopic fractionations of Mg and Ca, however no difference was found in the case of Sr. In this presentation, the possible mechanism will be discussed.

  2. 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.

  3. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    Science.gov (United States)

    Wong, Stanislaus; Zhang, Fen

    2016-06-28

    The present invention provides a method of producing a crystalline rare earth phosphate nanostructure. The method comprising: providing a rare earth metal precursor solution and providing a phosphate precursor solution; placing a porous membrane between the metal precursor solution and the phosphate precursor solution, wherein metal cations of the metal precursor solution and phosphate ions of the phosphate precursor solution react, thereby producing a crystalline rare earth metal phosphate nanostructure.

  4. Exciton localization in solution-processed organolead trihalide perovskites

    Science.gov (United States)

    He, Haiping; Yu, Qianqian; Li, Hui; Li, Jing; Si, Junjie; Jin, Yizheng; Wang, Nana; Wang, Jianpu; He, Jingwen; Wang, Xinke; Zhang, Yan; Ye, Zhizhen

    2016-03-01

    Organolead trihalide perovskites have attracted great attention due to the stunning advances in both photovoltaic and light-emitting devices. However, the photophysical properties, especially the recombination dynamics of photogenerated carriers, of this class of materials are controversial. Here we report that under an excitation level close to the working regime of solar cells, the recombination of photogenerated carriers in solution-processed methylammonium-lead-halide films is dominated by excitons weakly localized in band tail states. This scenario is evidenced by experiments of spectral-dependent luminescence decay, excitation density-dependent luminescence and frequency-dependent terahertz photoconductivity. The exciton localization effect is found to be general for several solution-processed hybrid perovskite films prepared by different methods. Our results provide insights into the charge transport and recombination mechanism in perovskite films and help to unravel their potential for high-performance optoelectronic devices.

  5. Controlled charge exchange between alkaline earth metals and their ions

    Science.gov (United States)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  6. Structural variations in layered alkaline earth metal cyclohexyl phosphonates

    Indian Academy of Sciences (India)

    Ramaswamy Murugavel; Nayanmoni Gogoi

    2009-06-01

    Two series of alkaline earth metal cyclohexyl phosphonates, M(C6H11PO3H)2(H2O) (M = Ca, Sr and Ba) (1–3) and M(C6H11PO3)(H2O) (M = Mg, Ca, Sr, and Ba) (4–7) have been synthesized under mild reaction conditions. All new compounds have been characterized using elemental analysis, IR, TGA and powder X-ray diffraction techniques. The molecular structure of compound 2 determined using single crystal X-ray diffraction technique reveals a layered polymeric structure.

  7. Electron-phonon coupling in the rare-earth metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

    We have estimated the strength of the mass enhancement of the conduction electrons due to electron-phonon interaction in the rare metals Sc, Y, and La–Lu. The underlying self-consistent energy bands were obtained by means of the scalar relativistic linear-muffin-tin-orbital method, and the electron......-phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4...

  8. Synthesis and luminescence of some rare earth metal complexes

    Science.gov (United States)

    Bochkarev, Mikhail N.; Pushkarev, Anatoly P.

    2016-12-01

    In the present paper the synthesis, photoand electroluminescent properties of new rare earth metal complexes prepared and studied at the Razuvaev Institute of Organometallic Chemistry during the last decade are reviewed. The obtained compounds give luminescence in UV, visible and NIR regions. The substituted phenolates, naphtholates, mercaptobenzothiazolate, 8-oxyquinolinolate, polyfluorinated alcoholates and chalcogenophosphinates were used as ligands. The synthesis and structure of unusual three-nuclear sulfidenitride clusters of Nd and Dy are described. The new excitation mechanism of ytterbium phenolates and naphtholates, which includes the stage of reversible reduction of Yb to divalent state and oxidation of the ligands in the excitation process, is discussed.

  9. Quantum computing with alkaline-Earth-metal atoms.

    Science.gov (United States)

    Daley, Andrew J; Boyd, Martin M; Ye, Jun; Zoller, Peter

    2008-10-24

    We present a complete scheme for quantum information processing using the unique features of alkaline-earth-metal atoms. We show how two completely independent lattices can be formed for the 1S0 and 3P0 states, with one used as a storage lattice for qubits encoded on the nuclear spin, and the other as a transport lattice to move qubits and perform gate operations. We discuss how the 3P2 level can be used for addressing of individual qubits, and how collisional losses from metastable states can be used to perform gates via a lossy blockade mechanism.

  10. Homometallic rare-Earth metal phosphinidene clusters: synthesis and reactivity.

    Science.gov (United States)

    Wang, Kai; Luo, Gen; Hong, Jianquan; Zhou, Xigeng; Weng, Linhong; Luo, Yi; Zhang, Lixin

    2014-01-20

    Two new trinuclear μ3 -bridged rare-earth metal phosphinidene complexes, [{L(Ln)(μ-Me)}3 (μ3 -Me)(μ3 -PPh)] (L=[PhC(NC6 H4 iPr2 -2,6)2 ](-) , Ln=Y (2 a), Lu (2 b)), were synthesized through methane elimination of the corresponding carbene precursors with phenylphosphine. Heating a toluene solution of 2 at 120 °C leads to an unprecedented ortho CH bond activation of the PhP ligand to form the bridged phosphinidene/phenyl complexes. Reactions of 2 with ketones, thione, or isothiocyanate show clear phospha-Wittig chemistry, giving the corresponding organic phosphinidenation products and oxide (sulfide) complexes. Reaction of 2 with CS2 leads to the formation of novel trinuclear rare-earth metal thione dianion clusters, for which a possible pathway was determined by DFT calculation. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Correlations in rare-earth transition-metal permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Skomski, R., E-mail: rskomski@neb.rr.com; Manchanda, P. [Department of Physics and Astronomy and NCMN, University of Nebraska, Lincoln, Nebraska 68508 (United States); Kashyap, A. [School of Basic Science, IIT Mandi, Mandi, Himachal Pradesh (India)

    2015-05-07

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo{sub 5}. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  12. Molecular rare-earth-metal hydrides in non-cyclopentadienyl environments.

    Science.gov (United States)

    Fegler, Waldemar; Venugopal, Ajay; Kramer, Mathias; Okuda, Jun

    2015-02-02

    Molecular hydrides of the rare-earth metals play an important role as homogeneous catalysts and as counterparts of solid-state interstitial hydrides. Structurally well-characterized non-metallocene-type hydride complexes allow the study of elementary reactions that occur at rare-earth-metal centers and of catalytic reactions involving bonds between rare-earth metals and hydrides. In addition to neutral hydrides, cationic derivatives have now become available.

  13. Supramolecular structures constructed from three novel rare earth metal complexes

    Indian Academy of Sciences (India)

    Huaze Dong; Xiaojun Feng; Xia Liu; BiN Zheng; Jianhong Bi; Yan Xue; Shaohua Gou; Yanping Wang

    2015-05-01

    Three rare earth metal supramolecular complexes, {[Tb(2)4](ClO4)3·2H2O(1), [Eu(2)2(H2O)5] (ClO4)3(2) and [Gd(NO3)3(2)2]·2CH3CH2OH(3) ( 2 = 3-Dimethylamino-1-pyridin-2-yl-propenone), have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. The crystal structure analysis reveals that the coordination numbers of three complexes (1–3) are 8, 9 and 10, respectively. Three complexes assembled into 3D frameworks based on C-H⋯O, O-H⋯O hydrogen bond linkages.

  14. The DNA-binding and bioactivity of rare earth metal complexes.

    Science.gov (United States)

    Yang, Li; Wang, Bochu; Tan, Jun; Zhu, Liancai

    2013-08-01

    Recently more and more attention is paid to the rare earth metal complexes, because the properties of the rare earth metals are similar to those of the transition metals such as the similar atomic and the ionic radius. A large number of rare metal complexes were synthesized, and their bioactivities were also studied. This review highlights recent researches on the interaction of some rare earth metal complexes with DNA, analyzes how the configuration of the complexes influences the binding affinity, and focuses on the pharmacological activities of the complexes, such as anticancer, antibacterial, antioxidant, anti-inflammatory and anti-virus.

  15. 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)

  16. Distinct exciton dissociation behavior of organolead trihalide perovskite and excitonic semiconductors studied in the same system.

    Science.gov (United States)

    Hu, Miao; Bi, Cheng; Yuan, Yongbo; Xiao, Zhengguo; Dong, Qingfeng; Shao, Yuchuan; Huang, Jinsong

    2015-05-13

    The nonexcitonic character for organometal trihalide perovskites is demonstrated by examining the field-dependent exciton dissociation behavior. It is found that photogenerated excitons can be effectively dissociated into free charges inside perovskite without the assistance of charge extraction layer or external field, which is a stark contrast to the charge-separation behavior in excitonic materials in the same photovoltaic operation system.

  17. Rare-earth metal prices in the USA ca. 1960 to 1994

    Science.gov (United States)

    Hedrick, James B.

    1997-01-01

    Rare-earth metal prices were compiled from the late 1950s and early 1960s through 1994. Although commercial demand for rare-earth metals began in 1908, as the alloy mischmetal, commercial quantities of a wide range of individual rare-earth metals were not available until the late 1950s. The discovery of a large, high-grade rare-earth deposit at Mountain Pass. CA, USA, in 1949, was significant because it led to the production of commercial quantities or rare-earth elements that reduced prices and encouraged wider application of the materials. The availability of ore from Mountain Pass, and other large rare-earth deposits, especially those in Australia and China, has provided the world with abundant resources for rare-earth metal production. This availability, coupled with improved technology from Government and private-sector metallurgical research, has resulted in substantial decreases in rare-earth metal prices since the late 1950s and early 1960s. Price series for the individual rare-earth metals (except promethium) are quoted on a kilogram basis from the late 1950s and early 1960s through 1994. Prices are given in US dollars on an actual and constant dollar basis. Industrial and economic factors affecting prices during this time period are examined.

  18. sup 29 Si magic angle spinning NMR spectra of alkali metal, alkaline earth metal, and rare earth metal ion exchanged Y zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Kueijung; Chern, Jeryoung (Tsinghua Univ., Taiwan (China))

    1989-02-23

    The variation of the extraframework cation location in groups IA and IIA metals and rare earth metal (RE) Y zeolites as a function of the dehydration and the rehydration is monitored by {sup 29}Si MAS NMR. Unheated hydrated zeolites give similar {sup 29}Si spectra as they present the similar cation distributions. Upon dehydration a high-field shift is observed which correlates with the distortion of bond angles in silicon-oxygen tetrahedra. The line shapes of {sup 29}Si spectra depend on the nature and the location of the exchangeable cations and the occupancy of the different sites in dehydrated and rehydrated states. The correlation between the line shape of {sup 29}Si spectra and the migration of cations from the supercages to the sodalite cages after heating treatment was studied. The results of {sup 29}Si NMR agree with the known structure data.

  19. Process optimization and kinetics for leaching of rare earth metals from the spent Ni-metal hydride batteries.

    Science.gov (United States)

    Meshram, Pratima; Pandey, B D; Mankhand, T R

    2016-05-01

    Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features.

  20. Adsorption of rare earth metal ion by algae. Sorui ni yoru kidorui ion no kyuchaku

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, T.; Yazawa, A. (Miyagi National College of Technology, Miyagi (Japan))

    1994-02-25

    This paper reports the result of investigations on adsorption of rare earth metal ion by using algae, and adsorption of different metal ions by using egg white and soy bean protein. Rare earth metal ion is adsorbed at a considerably high rate with alga powder of different kinds. The adsorption has been judged to be cation exchange reactive adsorption, while with use of spirulina and chlorella a maximum value of adsorption rate has been observed at pH from 3 to 4.5. Therefore, selective adsorption and separation of metal ions other than rare earth metal ion has become possible. When the blue pigment extracted from spirulina, the spirulina blue, is used, the rare earth metal ion had its selective adsorption and separation performance improved higher than using spirulina itself at pH from 3 to 4.5. As a result of adsorption experiment using egg white and soy bean protein, it has been found that the metal ion adsorption behavior of the spirulina blue depends on coagulative action of protein structure to some extent. However, the sharp selective adsorption performance on rare earth metal ion due to particular pH strength has been found because of actions unique to the pigment structure of phycocyanin, a major component in the spirulina blue. 7 refs., 19 figs.

  1. A Density Functional study of Covalency in the Trihalides of Lutetium and Lawrencium

    CERN Document Server

    Kullie, Ossama

    2016-01-01

    In this work we present a four component relativistic theoretical investigation of the trihalides of lutetium and lawrencium, LuX3, LrX3 (X= F, Cl, Br, I) respectively using density functional theory (DFT) with different density functional and a geometrical optimisation procedure as implemented in DIRAC-package. The results show the trend of bonding from lighter to the heavier halide atoms and between 4f/5f atoms Lu and Lr.

  2. THE TRANSFER OF ALKALINE EARTH-METAL ION AT W/NB INTERFACE FACILITATED BY JOSAMYCIN

    Institute of Scientific and Technical Information of China (English)

    范瑞溪; 狄俊伟

    1991-01-01

    This paper describes the invesligation of the transfer behaviour of the alkaline earth-metal cations across the water/nitrobenzene interface facilitated by josamycin in the nitrobenzene phase using semi-differential cyclic voltammetry .The peak height is directly proportional to the concentration of josaycin (nb) and to the potential scan rate.The complexes formed from alkaline earth-metal ions and josamycin at the w/nb interface are ML22+ ion.

  3. Magnetic Behavior of Some Rare-Earth Transition-Metal Perovskite Oxide Systems

    Institute of Scientific and Technical Information of China (English)

    Kenji Yoshii; Akio Nakamura; Masaichiro Mizumaki; Naoshi Ikeda; Jun'ichiro Mizuki

    2004-01-01

    Magnetic properties were investigated for the rare-earth 3d-transition metal oxides with the perovskite structure. Intriguing magnetic phenomena were reviewed for a few systems:magnetization peak effect in the titanates, magnetization reversal in the chromites and metallic ferromagnetism in the cobaltites. The results suggest an important role of the rare-earth ions for the magnetic properties of such complex oxides.

  4. Rare Earth Application in Sealing Anodized Al-Based Metal Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new method for corrosion protection of Al-based metal matrixcomposites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves.The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.

  5. High-temperature corrosion of metals in the salt and metallic melts containing rare earths

    Science.gov (United States)

    Karpov, V. V.; Abramov, A. V.; Zhilyakov, A. Yu.; Belikov, S. V.; Volkovich, V. A.; Polovov, I. B.; Rebrin, O. I.

    2016-09-01

    A complex of independent methods was employed to study the corrosion resistance of molybdenum, zirconium, tantalum and tungsten in chloride, chloride-fluoride and fluoride-oxide melts based on LiCl, CaCl2, NaCl- KCl, LiF, and containing rare earths. Tests were conducted for 30 h at 750-1050 °C. The metals showed excellent corrosion resistance in fused chlorides (the corrosion rates were below 0.0005 g/(m2 h). Despite the presence of chemically active fluoride ions in the chloride-fluoride melts, the metals studied also showed very low corrosion rates, except molybdenum, for which the rate of corrosion was 0,8 g/(m2 h). The corrosion resistance of tantalum was considerably reduced in the fluoride-oxide melts; the corrosion rate was over 1 g/(m2 h) corresponding to the 8-th grade of stability and placing tantalum to the group of "low stability" materials.

  6. High-purity rare-earth metals: preparation, properties, and application

    Institute of Scientific and Technical Information of China (English)

    Kol'chugina; N.; B.; Burkhanov; G.; S.; Chistyakov; O.; D.; Burkhanov; Yu.; S.

    2005-01-01

    In recent years, the ever-growing interest of investigators to the study of rare-earth metals REM) is observed owing to unique properties of the metals and potential uses in electronics, laser technology, space technology, medicine, and many other high-technology applications.……

  7. High-purity rare-earth metals: preparation, properties, and application

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ In recent years, the ever-growing interest of investigators to the study of rare-earth metals REM) is observed owing to unique properties of the metals and potential uses in electronics, laser technology, space technology, medicine, and many other high-technology applications.

  8. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability: Description of the 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...

  9. Progress of Study on Application of Rare Earth Metals in Steels

    Institute of Scientific and Technical Information of China (English)

    Wang Longmei; Lin Qin; Ji Jingwen; Lan Denian

    2004-01-01

    With the improvement of the clean steel by degrees, the functions of rare earth metals in steel are more focused on modification of inclusions and micro alloying.The new study concerning the application of RE metals in clean steels were investigated by ICP, metallographic examination, SEM, EDS, EPMA, TEM and IMMA.The mechanism of corrosion resistance in the weather resistance steel was clarified.The mechanism of abrasion resistance and the life of fatigue enhanced in the RE - heavy rails steel were discussed.Progress in study of application of rare earth metals in steels (including weather resistance steel, low alloy steel, and heavy rails steel) was covered in this paper.

  10. 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....

  11. Metal-silicate partitioning during core formation on super-Earths

    Science.gov (United States)

    Schaefer, L. K.; Jacobsen, S. B.; Petaev, M. I.; Sasselov, D. D.; Remo, J. L.

    2015-12-01

    Separation of the Earth into a rocky mantle and metallic Fe core is a problem long studied in the planetary science community (e.g. [1]). The timing of core formation influences the abundances of the siderophile elements found in the Earth's mantle, and the mechanism of core formation influences the degree of chemical equilibration between the rocky mantle and the core at the time of metal separation. However, limited work has been done on formation of metallic cores and its effects on mantle chemistry in rocky planets larger than the Earth. Super-Earths, exoplanets with masses up to ~ 5 Earth masses and radii up to ~1.6-1.7 Earth radii, have significantly larger internal pressures and consequently higher internal temperatures than the Earth, therefore conclusions from Earth-centric studies of core formation may be erroneous. Partitioning coefficients for many of the relevant elements (e.g. Fe, Ni, Si, O, etc.) are available in the literature, but only to relatively low pressures. The relevant pressures for super-Earths are significantly larger. However, data on Fe-O-Ni-Si partitioning at pressures (200-500 GPa) and temperatures relevant to super-Earths have been measured by laser-induced shocks with the ZBL laser at Sandia National Laboratory with a method described in [2]. We will present a model which integrates this data with lower pressure partition coefficients from the literature (e.g. [3],[4],[5]), with special emphasis on Fe and O, to describe partitioning behavior at high pressures and discuss its implications for core size and composition on rocky super-Earths. [1] Ringwood, A.E. (1977) Geochem. J. 11, 111-135. [2] Remo, J.L., Petaev, M.I., Jacobsen, S. B. (2008) LPSC abstract, 1420. [3] Frost, D.J. et al. (2010) JGR, B02202. [4] Kombayashi, T. (2014) JGR, 4164-4177. [5] Rubie, D.C. et al. (2011) EPSL, 301, 31-42. [5

  12. Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

    Energy Technology Data Exchange (ETDEWEB)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin (UC)

    2016-08-30

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  13. 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.

  14. Maternal exposure to alkali, alkali earth, transition and other metals: Concentrations and predictors of exposure.

    Science.gov (United States)

    Hinwood, A L; Stasinska, A; Callan, A C; Heyworth, J; Ramalingam, M; Boyce, M; McCafferty, P; Odland, J Ø

    2015-09-01

    Most studies of metals exposure focus on the heavy metals. There are many other metals (the transition, alkali and alkaline earth metals in particular) in common use in electronics, defense industries, emitted via combustion and which are naturally present in the environment, that have received limited attention in terms of human exposure. We analysed samples of whole blood (172), urine (173) and drinking water (172) for antimony, beryllium, bismuth, cesium, gallium, rubidium, silver, strontium, thallium, thorium and vanadium using ICPMS. In general most metals concentrations were low and below the analytical limit of detection with some high concentrations observed. Few factors examined in regression models were shown to influence biological metals concentrations and explained little of the variation. Further study is required to establish the source of metals exposures at the high end of the ranges of concentrations measured and the potential for any adverse health impacts in children.

  15. Triiodide and mixed tri-halide anions from negative ion electrospray ionization of alkali halide solutions

    Science.gov (United States)

    Shukla, Anil

    2017-10-01

    Electrospray ionization of alkali halide solutions in the negative ion mode results in the formation of cluster ions of the general formula, (MX)nX-. However, alkali iodides form triiodide anion, I3-, in high abundance in addition to cluster ions. Br3- ions are observed in low abundance. Also, mixed tri-halide anions, I2Y-, are observed in high abundance when a small amount (<1%) of KI is added to other alkali halide solutions. These results are explained by the uniquely different physical characteristics of lithium and the iodide ions compared with others in the series.

  16. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles.

    Science.gov (United States)

    Derom, S; Berthelot, A; Pillonnet, A; Benamara, O; Jurdyc, A M; Girard, C; Colas des Francs, G

    2013-12-13

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion's excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  17. Structure of Some 4f Rare Earth Liquid Metals - A Charged Hard Sphere Approach

    Institute of Scientific and Technical Information of China (English)

    P.B. Thakor; P.N. Gajjar; A.R. Jani

    2006-01-01

    A well-established pseodopotential is used to study the structure of some 4f rare earth liquid metals (Ce,Pr, Eu, Gd, Tb, and Yb). The structure factor S(q), pair distribution function g(r), interatomic distance r1, and coordination number n1 are calculated using Charged Hard Sphere (CHS) reference system. To introduce the exchange and correlation effects, the local field correction due to Sarkar et al. (S) is applied. The present investigation is successful in generating the structural information of Ce, Pr, Eu, Gd, Tb, and Yb 4f rare earth liquid metals.

  18. Inference on the Nature and the Mass of Earth's Late Veneer from Noble Metals and Gases

    CERN Document Server

    Dauphas, N

    2001-01-01

    Noble metals and gases are very sensitive to the late accretion to the Earth of asteroids and comets. We present mass balance arguments based on these elements that indicate that 0.7E22-2.7E22 kg of extraterrestrial bodies struck the Earth after core formation and that comets comprised less than 1E-5 by mass of the impacting population. These results imply that the dynamics of asteroids and comets changed drastically with time and that biogenic elements and prebiotic molecules were not delivered to the Earth by comets but rather by carbonaceous asteroids.

  19. New technology of extracting the amount of rare earth metals from the red mud

    Science.gov (United States)

    Martoyan, G. A.; Karamyan, G. G.; Vardan, G. A.

    2016-01-01

    The paper outlined the environmental and economic problems associated with red mud - the waste generated in processing of bauxite ore for aluminum production. The chemical analysis of red mud has identified a number of useful elements including rare earth metals. The electromembrane technology of red mud processing with extraction of valuable elements is described. A possible scheme of separation of these metals through electrolysis is also given.

  20. Adsorption of alkali, alkaline-earth, and 3d transition metal atoms on silicene

    Science.gov (United States)

    Sahin, H.; Peeters, F. M.

    2013-02-01

    The adsorption characteristics of alkali, alkaline-earth, and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, work function, and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na, and K, adsorb to hollow sites without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene, metalization of silicene takes place. Trends directly related to atomic size, adsorption height, work function, and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline-earth metals on silicene is entirely different from their adsorption on graphene. The adsorption of Be, Mg, and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo, and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic, and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal, and semiconducting behavior. For all metal adsorbates, the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

  1. High-Field Magnetization of Light Rare-Earth Metals

    DEFF Research Database (Denmark)

    McEwen, K.A.; Cock, G.J.; Roeland, L.W.;

    1973-01-01

    The magnetization of single crystals of Eu, Sm, Nd, Pr, and Pr-Nd alloys has been measured in fields up to 37 T (370 kG). The results give new information on the magnetic properties of these metals. Of particular interest is a first-order transition from a nonmagnetic to a metamagnetic phase...... in double-hexagonal close-packed Pr, due to the crossing of crystal-field levels, when a field of about 32 T is applied in the hard direction at low temperatures....

  2. A Graphical Procedure for the Simultaneous Determination of the Distribution Constant of Iodine and the Stability Constants of Trihalide Anions.

    Science.gov (United States)

    Kahwa, I. A.

    1984-01-01

    Discusses a graphical procedure which allows the distribution constant of iodine to be determined simultaneously with the trihalide anion stability constant. In addition, the procedure extends the experimental chemistry from distribution equilibria to important thermodynamic and bonding features. Advantages of using the procedure are also…

  3. Tracking environmental impacts in global product chains - Rare Earth Metals and other critical metals used in the cleantech industry

    Energy Technology Data Exchange (ETDEWEB)

    Pathan, A.; Schilli, A.; Johansson, J.; Vehvilaeinen, I.; Larsson, A.; Hutter, J.

    2013-03-15

    Metals form a central part of the global economy, but their extraction and supply are linked to several environmental and social concerns. This study aims to create a picture of the supply chain of Rare Earth Metals (REMs) and other critical metals used in the clean technology (cleantech) sectors of electric vehicles and solar panels. The study examines how Nordic cleantech companies are aware and acting on the challenges related to the lifecycle of these metals and what are the potentials to minimise environmental and social impacts. Recommendations of the study can be summarised as three initiatives: establishment of an awareness platform and roundtable initiative (short-term), research and information gathering (mid-term), and development of closed-loop solutions (long-term). (Author)

  4. 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....

  5. Doping of graphite by an alkaline-earth metal to reduce the work function

    NARCIS (Netherlands)

    Baturin, AS; Nikolski, KN; Knyazev, AI; Tchesov, RG; Sheshin, EP

    2004-01-01

    A technique for reducing the work function of a field-emission graphite cathode by doping it by an alkaline-earth metal (barium) is suggested. A model of formation of a barium monolayer on the cathode surface is proposed. Field-emission tests show that the operating voltage of the doped cathode is l

  6. Calculated Structural Phase-Transitions in the Alkaline-Earth Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1982-01-01

    The local-density approximation and the linear muffin-tin orbital method have been used within the atomic-sphere approximation to calculate structural energy differences for all the alkaline earth metals at zero temperature. At ordinary pressure the calculations predict the crystal structure...

  7. Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates.

    Science.gov (United States)

    Docampo, Pablo; Ball, James M; Darwich, Mariam; Eperon, Giles E; Snaith, Henry J

    2013-01-01

    Organometal trihalide perovskite solar cells offer the promise of a low-cost easily manufacturable solar technology, compatible with large-scale low-temperature solution processing. Within 1 year of development, solar-to-electric power-conversion efficiencies have risen to over 15%, and further imminent improvements are expected. Here we show that this technology can be successfully made compatible with electron acceptor and donor materials generally used in organic photovoltaics. We demonstrate that a single thin film of the low-temperature solution-processed organometal trihalide perovskite absorber CH3NH3PbI3-xClx, sandwiched between organic contacts can exhibit devices with power-conversion efficiency of up to 10% on glass substrates and over 6% on flexible polymer substrates. This work represents an important step forward, as it removes most barriers to adoption of the perovskite technology by the organic photovoltaic community, and can thus utilize the extensive existing knowledge of hybrid interfaces for further device improvements and flexible processing platforms.

  8. 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.

  9. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

    Science.gov (United States)

    Alkahtani, Saleh A.; Elgallad, Emad M.; Tash, Mahmoud M.; Samuel, Agnes M.; Samuel, Fawzy H.

    2016-01-01

    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. PMID:28787844

  10. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys.

    Science.gov (United States)

    Alkahtani, Saleh A; Elgallad, Emad M; Tash, Mahmoud M; Samuel, Agnes M; Samuel, Fawzy H

    2016-01-13

    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.

  11. PERVAPORATION SEPARATION OF WATER-ACETIC ACID MIXTURES THROUGH AN-co-AA MEMBRANES TREATED WITH RARE EARTH METAL IONS

    Institute of Scientific and Technical Information of China (English)

    SHEN Zhiquan; ZHANG Fuyao; ZHANG Yifeng

    1995-01-01

    Pervaporation separation of water-acetic acid mixtures through Poly (AN-co-AA)membranes and rare earth metal ions treated Poly(AN-co-AA)membranes was investigated for the first time. The results showed that the treatment with rare earth metal ions could greatly improve the characteristics of the separation of water-acetic acid mixtures.

  12. 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.

  13. 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.

  14. Red-emitting alkaline-earth rare-earth pentaoxometallates powders prepared by metal carboxylates solution

    Indian Academy of Sciences (India)

    Kyu-Seog Hwang; Sung-Dae Kim; Seung Hwangbo; Jin-Tae Kim

    2013-06-01

    Moisture-insensitive metal carboxylates that are mostly liquids at room temperature have been first applied to the preparation of strontium europium aluminate (Sr2EuAlO5) powders for red-emitting phosphor under near ultraviolet radiation. Strontium naphthenate, aluminium-2-ethylhexanoate and europium-2-ethylhexanoate were dissolved with toluene to prepare starting solution. 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 narrow size distribution confirmed by FE–SEM observation, strong red emission at 615nm under the excitation of 395nm maximum was reached, then the higher annealed samples at above 1100 °C gave the lower emission intensities.

  15. Selective extraction and recovery of rare earth metals from phosphor powders in waste fluorescent lamps using an ionic liquid system.

    Science.gov (United States)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo; Kamiya, Noriho; Goto, Masahiro

    2013-06-15

    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.

  16. High pressure phase transitions in the rare earth metal erbium to 151 GPa.

    Science.gov (United States)

    Samudrala, Gopi K; Thomas, Sarah A; Montgomery, Jeffrey M; Vohra, Yogesh K

    2011-08-10

    High pressure x-ray diffraction studies have been performed on the heavy rare earth metal erbium (Er) in a diamond anvil cell at room temperature to a pressure of 151 GPa and Er has been compressed to 40% of its initial volume. The rare earth crystal structure sequence hcp → Sm type → dhcp → distorted fcc (hcp: hexagonal close packed; fcc: face centered cubic; dhcp: double hcp) is observed in Er below 58 GPa. We have carried out Rietveld refinement of crystal structures in the pressure range between 58 GPa and 151 GPa. We have examined various crystal structures that have been proposed for the distorted fcc (dfcc) phase and the post-dfcc phase in rare earth metals. We find that the hexagonal hR 24 structure is the best fit between 58 and 118 GPa. Above 118 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.9%. We have also established a clear trend for the pressure at which a post-dfcc phase is formed in rare earth metals and show that there is a monotonic increase in this pressure with the filling of 4f shell.

  17. Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect.

    Science.gov (United States)

    Samsonowicz, M; Regulska, E; Lewandowski, W

    2011-11-01

    The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions. The vibrational FT-IR (in KBr and ATR techniques) and (1)H and (13)C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg→Ba were compared with series of univalent metal Li→Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.

  18. Rare earth element recycling from waste nickel-metal hydride batteries.

    Science.gov (United States)

    Yang, Xiuli; Zhang, Junwei; Fang, Xihui

    2014-08-30

    With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained.

  19. Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

    Science.gov (United States)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

  20. Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies)

    OpenAIRE

    Alexandr Ivanovich Khanchuk; Aleksandr Alekseevich Yudakov; Mikhail Azaryevich Medkov; Leonid Nikolayevich Alekseyko; Andrey Vasilyevich Taskin; Sergey Igorevich Ivannikov

    2016-01-01

    The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH4HF2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rare earth metals) between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples ...

  1. Modification of Non-Metallic Inclusions by Rare-Earth Elements in Microalloyed Steels

    OpenAIRE

    Opiela M.; Grajcar A.

    2012-01-01

    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...

  2. Thermal oxidation of the surface of binary aluminum alloys with rare-earth metals

    Science.gov (United States)

    Akashev, L. A.; Popov, N. A.; Kuznetsov, M. V.; Shevchenko, V. G.

    2015-05-01

    The kinetics of oxidation of the surface of Al alloys with 1-2.5 at % rare-earth metals (REMs) at 400-500°C in air was studied by ellipsometry and X-ray photoelectron spectroscopy (XPS). The addition (1-2.5 at % REM) of all rare-earth metals to aluminum was shown to increase the thickness of the oxide layer. The addition of surfactant and chemically active REMs (Yb, Sm, La, and Ce) increased the rate of oxidation of solid aluminum most effectively. The oxidation can be accelerated by the polymorphic transformations of the individual REM oxides in the film. The surface activity of Sm with respect to solid Al was confirmed by XRS.

  3. Distribution of Rare Earth Metals in Technogenic Wastes of Energy Enterprises (Results of the Laboratory Studies

    Directory of Open Access Journals (Sweden)

    Alexandr Ivanovich Khanchuk

    2016-12-01

    Full Text Available The results of the research interaction between ash and slag samples from Vladivostok TPP’s landfills saturated with underburning and ammonium hydrodifluoride were given. It was found out that the reactions of the main components of a concentrate with NH4HF2 are flowing with creation of complex ammonium fluoro-metalate. It is shown that the distribution of REM (rare earth metals between foam and heavier products is going during the flotation process of carbon-containing ash and slag samples without significant concentrating. It is shown that the water leaching of fluoridated product lets transfer silicone, aluminum and iron salts into solution and concentrate rare earth elements in insoluble residue in the form of complex salts of NaLnF4 general formula. We propose a schematic diagram of hydrodifluoride recycling of carbon-containing sample, which provides concentrating of REM with incomplete separation of macro-components.

  4. Molecular dynamics of liquid alkaline-earth metals near the melting point

    Indian Academy of Sciences (India)

    J K Baria; A R Jani

    2010-10-01

    Results of the studies of the properties like binding energy, the pair distribution function (), the structure factor (), specific heat at constant volume, velocity autocorrelation function (VACF), radial distribution function, self-diffusion coefficient and coordination number of alkaline-earth metals (Be, Mg, Ca, Sr and Ba) near melting point using molecular dynamics (MD) simulation technique using a pseudopotential proposed by us are presented in this article. Good agreement with the experiment is achieved for the binding energy, pair distribution function and structure factor, and these results compare favourably with the results obtained by other such calculations, showing the transferability of the pseudopotential used from solid to liquid environment in the case of alkaline-earth metals.

  5. Solvation structures and dynamics of alkaline earth metal halides in supercritical water: A molecular dynamics study

    Science.gov (United States)

    Keshri, Sonanki; Mandal, Ratnamala; Tembe, B. L.

    2016-09-01

    Constrained molecular dynamics simulations of alkaline earth metal halides have been carried out to investigate their structural and dynamical properties in supercritical water. Potentials of mean force (PMFs) for all the alkaline earth metal halides in supercritical water have been computed. Contact ion pairs (CIPs) are found to be more stable than all other configurations of the ion pairs except for MgI2 where solvent shared ion pair (SShIP) is more stable than the CIP. There is hardly any difference in the PMFs between the M2+ (M = Mg, Ca, Sr, Ba) and the X- (X = F, Cl, Br, I) ions whether the second X- ion is present in the first coordination shell of the M2+ ion or not. The solvent molecules in the solvation shells diffuse at a much slower rate compared to the bulk. Orientational distribution functions of solvent molecules are sharper for smaller ions.

  6. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals

    KAUST Repository

    Shi, Dong

    2015-01-29

    The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3(MA = CH3NH3 +; X = Br- or I- ) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics.We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.

  7. Simultaneous band-gap narrowing and carrier-lifetime prolongation of organic–inorganic trihalide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingping; Liu, Gang; Gong, Jue; Hu, Qingyang; Schaller, Richard D.; Dera, Przemyslaw; Zhang, Dongzhou; Liu, Zhenxian; Yang, Wenge; Zhu, Kai; Tang, Yuzhao; Wang, Chuanyi; Wei, Su-Huai; Xu, Tao; Mao, Ho-kwang

    2016-07-21

    The organic-inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic materials. As regulated by Shockley-Queisser theory, a formidable materials science challenge for improvement to the next level requires further band-gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band-gap photovoltage. Herein, by applying controllable hydrostatic pressure, we have achieved unprecedented simultaneous enhancement in both band-gap narrowing and carrier-lifetime prolongation (up to 70% to -100% increase) under mild pressures at -0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon-electron interaction and maps a pioneering route toward a further increase in their photovoltaic performance.

  8. Simultaneous band-gap narrowing and carrier-lifetime prolongation of organic-inorganic trihalide perovskites.

    Science.gov (United States)

    Kong, Lingping; Liu, Gang; Gong, Jue; Hu, Qingyang; Schaller, Richard D; Dera, Przemyslaw; Zhang, Dongzhou; Liu, Zhenxian; Yang, Wenge; Zhu, Kai; Tang, Yuzhao; Wang, Chuanyi; Wei, Su-Huai; Xu, Tao; Mao, Ho-Kwang

    2016-08-09

    The organic-inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic materials. As regulated by Shockley-Queisser theory, a formidable materials science challenge for improvement to the next level requires further band-gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band-gap photovoltage. Herein, by applying controllable hydrostatic pressure, we have achieved unprecedented simultaneous enhancement in both band-gap narrowing and carrier-lifetime prolongation (up to 70% to ∼100% increase) under mild pressures at ∼0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon-electron interaction and maps a pioneering route toward a further increase in their photovoltaic performance.

  9. Simultaneous band-gap narrowing and carrier-lifetime prolongation of organic–inorganic trihalide perovskites

    Science.gov (United States)

    Kong, Lingping; Liu, Gang; Gong, Jue; Hu, Qingyang; Schaller, Richard D.; Dera, Przemyslaw; Zhang, Dongzhou; Liu, Zhenxian; Yang, Wenge; Zhu, Kai; Tang, Yuzhao; Wang, Chuanyi; Wei, Su-Huai; Xu, Tao; Mao, Ho-kwang

    2016-01-01

    The organic–inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic materials. As regulated by Shockley–Queisser theory, a formidable materials science challenge for improvement to the next level requires further band-gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band-gap photovoltage. Herein, by applying controllable hydrostatic pressure, we have achieved unprecedented simultaneous enhancement in both band-gap narrowing and carrier-lifetime prolongation (up to 70% to ∼100% increase) under mild pressures at ∼0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon–electron interaction and maps a pioneering route toward a further increase in their photovoltaic performance. PMID:27444014

  10. Formation of an integrated holding company to produce rare-earth metal articles

    Science.gov (United States)

    Bogdanov, S. V.; Grishaev, S. I.

    2013-12-01

    The possibility of formation of a Russian holding company for the production of rare-earth metal articles under conditions of its increasing demand on the world market is considered. It is reasonable to ensure stable business operation on the market under conditions of state-private partnership after the fraction of soled products is determined and supported by the competitive advantages of Russian products.

  11. 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......-ion anisotropy was due to an inadequate treatment of the large single-ion anisotropy leading to an incorrect expression for the spin-wave energy....

  12. Optimization of film synthesized rare earth transition metal permanent magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    Cadieu, F.J.

    1992-01-01

    Progress is reported in three areas: high coercivity Sm-Fe-Ti-V, Sm-Fe-Zr, and two element Sm-Fe Sm{sub 5}(Fe,T){sub 17} type crystalline phases; ThMn{sub 12} type pseudobinary SmFe{sub 12-x}T{sub x}(0{le}{times}{le}1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films. (DLC)

  13. Neutral binuclear rare-earth metal complexes with four μ₂-bridging hydrides.

    Science.gov (United States)

    Rong, Weifeng; He, Dongliang; Wang, Meiyan; Mou, Zehuai; Cheng, Jianhua; Yao, Changguang; Li, Shihui; Trifonov, Alexander A; Lyubov, Dmitrii M; Cui, Dongmei

    2015-03-25

    The first neutral rare-earth metal dinuclear dihydrido complexes [(NPNPN)LnH2]2 (2-Ln; Ln = Y, Lu; NPNPN: N[Ph2PNC6H3((i)Pr)2]2) bearing μ2-bridging hydride ligands have been synthesized. In the presence of THF, 2-Y undergoes intramolecular activation of the sp(2) C-H bond to form dinuclear aryl-hydride complex 3-Y containing three μ2-bridging hydride ligands.

  14. Ground-state properties of rare-earth metals: an evaluation of density-functional theory.

    Science.gov (United States)

    Söderlind, Per; Turchi, P E A; Landa, A; Lordi, V

    2014-10-15

    The rare-earth metals have important technological applications due to their magnetic properties, but are scarce and expensive. Development of high-performance magnetic materials with less rare-earth content is desired, but theoretical modeling is hampered by complexities of the rare earths electronic structure. The existence of correlated (atomic-like) 4f electrons in the vicinity of the valence band makes any first-principles theory challenging. Here, we apply and evaluate the efficacy of density-functional theory for the series of lanthanides (rare earths), investigating the influence of the electron exchange and correlation functional, spin-orbit interaction, and orbital polarization. As a reference, the results are compared with those of the so-called 'standard model' of the lanthanides in which electrons are constrained to occupy 4f core states with no hybridization with the valence electrons. Some comparisons are also made with models designed for strong electron correlations. Our results suggest that spin-orbit coupling and orbital polarization are important, particularly for the magnitude of the magnetic moments, and that calculated equilibrium volumes, bulk moduli, and magnetic moments show correct trends overall. However, the precision of the calculated properties is not at the level of that found for simpler metals in the Periodic Table of Elements, and the electronic structures do not accurately reproduce x-ray photoemission spectra.

  15. Low temperature route for the synthesis of rare earth transition metal borides and their hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Kramp, S.; Febri, M.; Joubert, J.C. [CNRS UMR 5628, Saint Martin d`Heres (France)

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y{sub 2}Co{sub 14}B, LnCo{sub 4}B, and YCo{sub 3}B{sub 2}. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000{degrees}C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle wishing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,...).

  16. A Low Temperature Route for the Synthesis of Rare Earth Transition Metal Borides and Their Hydrides

    Science.gov (United States)

    Kramp, S.; Febri, M.; Joubert, J. C.

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y2Co14B, LnCo4B, and YCo3B2. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000°C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle washing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,…).

  17. Focused-ion beam patterning of organolead trihalide perovskite for subwavelength grating nanophotonic applications

    KAUST Repository

    Alias, Mohd Sharizal

    2015-07-30

    The coherent amplified spontaneous emission and high photoluminescence quantum efficiency of organolead trihalide perovskite have led to research interest in this material for use in photonic devices. In this paper, the authors present a focused-ion beam patterning strategy for methylammonium lead tribromide (MAPbBr3) perovskite crystal for subwavelength grating nanophotonic applications. The essential parameters for milling, such as the number of scan passes, dwell time, ion dose, ion current, ion incident angle, and gas-assisted etching, were experimentally evaluated to determine the sputtering yield of the perovskite. Based on our patterning conditions, the authors observed that the sputtering yield ranged from 0.0302 to 0.0719 μm3/pC for the MAPbBr3 perovskite crystal. Using XeF2 for the focused-ion beam gas-assisted etching, the authors determined that the etching rate was reduced to between 0.40 and 0.97, depending on the ion dose, compared with milling with ions only. Using the optimized patterning parameters, the authors patterned binary and circular subwavelength grating reflectors on the MAPbBr3 perovskite crystal using the focused-ion beam technique. Based on the computed grating structure with around 97% reflectivity, all of the grating dimensions (period, duty cycle, and grating thickness) were patterned with nanoscale precision (>±3 nm), high contrast, and excellent uniformity. Our results provide a platform for utilizing the focused-ion beam technique for fast prototyping of photonic nanostructures or nanodevices on organolead trihalide perovskite.

  18. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Yin, Shu; Yoshida, Mizuki; Wu, Xiaoyong; Liu, Bin [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan); Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro [Department of Research Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Miyamae cho-7, Kofu 400-8511 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku Sendai 980-8577 (Japan)

    2015-09-15

    Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tin oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.

  19. Effect of Rare Earth Metals on Structure and Properties of Electroless Co-B Alloy Coating

    Institute of Scientific and Technical Information of China (English)

    宣天鹏; 张雷; 黄秋华

    2002-01-01

    The effect of rare earth metals cerium, lanthanum and yttrium on chemical composition, structure and properties of electroless Co-B alloy coating was studied. By plasma transmitting spectrograph, electron energy spectrometer, X-ray diffractometter, micro-hardometer and vibratory sample magnetometer the chemical constitution, structure and properties of the alloy coatings were analyzed and inspected. The results show that with a tiny quantity of rare earth metal added into Co-B alloy coating, the content of boron is decreased in the alloy coatings, and the kinds of rare earth metal have enormous effect on the structure and properties of electroless Co-B alloy coating. At the same time electroless Co-B alloy with amorphous structure is transformed to electroless Co-B-RE alloy with microcrystalline or crystalline structure. In this way microhardness of the coatings is increased remarkably. Cerium and lanthanum would also increase the saturated magnetic intensity and decrease coercitive force of the coating. So soft magnetization of the coatings would be improved.

  20. Rare earth elements and critical metal content of extracted landfilled material and potential recovery opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Gutiérrez-Gutiérrez, Silvia C.; Coulon, Frédéric; Jiang, Ying; Wagland, Stuart, E-mail: s.t.wagland@cranfield.ac.uk

    2015-08-15

    Highlights: • Samples from multiple core drills were obtained from 4× landfill sites in the UK. • Each sample analysed for rare earth elements, critical metals and valuable metals. • Two stage microwave digestion method ensuring high yield. • High quantities of copper and aluminium were observed in the soil layers of landfill. • Across 4× landfills aluminium and copper present has a value of around $400 million. - Abstract: Rare earth elements (REEs), Platinum group metals (PGMs) and other critical metals currently attract significant interest due to the high risks of supply shortage and substantial impact on the economy. Their uses in many applications have made them present in municipal solid waste (MSW) and in commercial and industrial waste (C&I), since several industrial processes produce by-products with high content of these metals. With over 4000 landfills in the UK alone, the aim of this study was to assess the existence of these critical metals within landfills. Samples collected from four closed landfills in UK were subjected to a two-step acid digestion to extract 27 metals of interest. Concentrations across the four landfill sites were 58 ± 6 mg kg{sup −1} for REEs comprising 44 ± 8 mg kg{sup −1} for light REEs, 11 ± 2 mg kg{sup −1} for heavy REEs and 3 ± 1 mg kg{sup −1} for Scandium (Sc) and 3 ± 1.0 mg kg{sup −1} of PGMs. Compared to the typical concentration in ores, these concentrations are too low to achieve a commercially viable extraction. However, content of other highly valuable metals (Al and Cu) was found in concentrations equating to a combined value across the four landfills of around $400 million, which increases the economic viability of landfill mining. Presence of critical metals will mainly depend on the type of waste that was buried but the recovery of these metals through landfill mining is possible and is economically feasible only if additional materials (plastics, paper, metallic items and other) are

  1. Metal-silicate Partitioning and Its Role in Core Formation and Composition on Super-Earths

    Science.gov (United States)

    Schaefer, Laura; Jacobsen, Stein B.; Remo, John L.; Petaev, M. I.; Sasselov, Dimitar D.

    2017-02-01

    We use a thermodynamic framework for silicate-metal partitioning to determine the possible compositions of metallic cores on super-Earths. We compare results using literature values of the partition coefficients of Si and Ni, as well as new partition coefficients calculated using results from laser shock-induced melting of powdered metal-dunite targets at pressures up to 276 GPa, which approaches those found within the deep mantles of super-Earths. We find that larger planets may have little to no light elements in their cores because the Si partition coefficient decreases at high pressures. The planet mass at which this occurs will depend on the metal-silicate equilibration depth. We also extrapolate the equations of state (EOS) of FeO and FeSi alloys to high pressures, and present mass–radius diagrams using self-consistent planet compositions assuming equilibrated mantles and cores. We confirm the results of previous studies that the distribution of elements between mantle and core will not be detectable from mass and radius measurements alone. While observations may be insensitive to interior structure, further modeling is sensitive to compositionally dependent properties, such as mantle viscosity and core freeze-out properties. We therefore emphasize the need for additional high pressure measurements of partitioning as well as EOSs, and highlight the utility of the Sandia Z-facilities for this type of work.

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

    Science.gov (United States)

    Judge, W. D.; Azimi, G.

    2017-08-01

    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.

  3. 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.

  4. Effects of alkaline earth metal ion complexation on amino acid zwitterion stability: Results from infrared action spectroscopy

    NARCIS (Netherlands)

    Bush, M. F.; Oomens, J.; Saykally, R. J.; Williams, E. R.

    2008-01-01

    The structures of isolated alkaline earth metal cationized amino acids are investigated using infrared multiple photon dissociation (IRMPD) spectroscopy and theory. These results indicate that arginine, glutamine, proline, serine, and valine all adopt zwitterionic structures when complexed with diva

  5. 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.

  6. Improvement of corrosion resistance of magnesium metal by rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Takenaka, Toshihide [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi 441-8580 (Japan)], E-mail: takenaka@pse.tut.ac.jp; Ono, Takami; Narazaki, Yuji; Naka, Yusuke; Kawakami, Masahiro [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi 441-8580 (Japan)

    2007-11-20

    Mg metal containing rare earth metals (REs) can be electrowon directly by molten salt electrolysis. The clarification of the optimum RE content in Mg is necessary to fix the electrolytic conditions in the direct electrowinning of Mg with RE. From this point of view, effect of RE addition in Mg metal on its corrosion property was studied in detail in this study. The specimen was prepared by adding La, Nd, or Ce in melted Mg metal, and its corrosion resistance was examined by an immersion test in 3 mass%-NaCl solution at room temperature. The corrosion resistance of Mg was improved greatly by adding a small amount of RE, whereas the excess addition of RE deteriorated the corrosion resistance. The optimum RE content was about 0.5 mass%. In this study, the corrosion property of Mg with an artificial surface oxide layer was also studied to clarify the effect of surface oxide. The corrosion resistance of Mg was particularly strengthened by conversion coating in a solution including La(NO{sub 3}){sub 3}, Nd(NO{sub 3}){sub 3}, or Ce(NO{sub 3}){sub 3}, with Mg(NO{sub 3}){sub 2}. This result suggests that the surface oxide film consisting of both Mg and RE gives ideal corrosion resistance to Mg metal. Mg metal with conversion coating including RE should also be of use as a corrosion-resistant material.

  7. How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

    Science.gov (United States)

    Kam, K.; Lemke, K.

    2014-12-01

    The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

  8. Recovery of rare earths from acid leach solutions of spent nickel-metal hydride batteries using solvent extraction

    Institute of Scientific and Technical Information of China (English)

    夏允; 肖连生; 田吉英; 李兆洋; 曾理

    2015-01-01

    The extraction of rare earths from acid leach solutions of spent nickel-metal hydride batteries using a primary amine ex-tractant of N1923 was studied. The effects of feed pH, temperature, agitation rate and time on the extraction of rare earths, as well as stripping agent composition and concentration, phase ratio on the stripping were investigated. In addition, the extraction isotherm was determined. The pilot plant test results showed that the extraction of rare earths reached 99.98% after a five-stage counter current ex-traction. The mixed rare earths oxalates with the 99.77% purity of rare earth elements and impurity content less than 0.05% were ob-tained by the addition of oxalic acids in loaded strip liquors. The extractant exhibited good selectivity of rare earths over base metals of iron, nickel, copper and manganese.

  9. Influence of rare earth metals on the nucleation and solidification behavior of iron and 1045 steel

    Science.gov (United States)

    Li, H.; McLean, A.; Rutter, J. W.; Sommerville, I. D.

    1988-06-01

    Two series of experiments have been conducted to determine the influence of rare earth additions on the nucleation and crystallization behavior of pure iron and 1045 steel. In the first series, additions of rare earth suicide or cerium dioxide powder to two-Kg 1045 steel ingots indicated that rare earth suicide can refine the as-cast structure of such ingots. However, if the holding time after rare earth silicide addition is over two minutes, the grain refinement decreases. With cerium dioxide additions, a relatively large columnar zone was obtained. In the second series, the effects of cerium metal or cerium dioxide powder additions on the degree of undercooling obtainable in pure iron and 1045 steel were examined by the lévitation melting method. Surface tension measurements of the levitated droplets were carried out at the same time to investigate the possible effects of surface tension variations on the nucleation and crystallization behavior of the metals. The experimental data show that rare earth inclusions can greatly reduce the degree of undercooling of iron and steel, and that a small amount of dissolved cerium can further reduce the degree of undercooling of levitated droplets. The structure and reaction products obtained with Fe-Ce levitated droplets were examined with both optical and scanning electron microscopy as well as X-ray diffraction analysis. The experimental results clearly indicated that cerium solute redistribution during solidification is the dominant factor in refining the as-cast structure. A nucleation and solidification model for the Fe-Ce levitated droplets has been developed, which can successfully explain the experimental results.

  10. Impact Wear Properties of Metal-Plastic Multilayer Composites Filled with Glass Fiber Treated with Rare Earth Element Surface Modifier

    Institute of Scientific and Technical Information of China (English)

    程先华; 薛玉君

    2001-01-01

    The friction and wear properties of metal-plastic multilayer composites filled with glass fiber, which is treated with rare earth element surface modifier, under impact load and dry friction conditions were investigated. Experimental results show that the metal-plastic multilayer composite filled with glass fiber exhibits excellent friction and impact wear properties when using rare earth elements as surface modifier for the surface treatment of glass fiber.

  11. Extent of metal-silicate disequilibrium during accretion and early differentiation of the Earth

    Science.gov (United States)

    Rubie, D. C.; Nimmo, F.; Morbidelli, A.; Frost, D. J.

    2012-12-01

    Earth, Mars, Venus and Mercury accreted on a timescale of 10-100 My through a series of violent collisions with planetesimals and embryos. The high energy of such impacts was sufficient to cause deep magma ocean formation which facilitated the segregation of metal and silicate liquids. Planetary cores thus formed as a multistage process that was inseparable from the accretion process. In order to better understand the formation and early differentiation of the terrestrial planets, we are integrating a multistage core-formation model with N-body accretion simulations. Constraints on model parameters are the compositions of the Earth's primitive mantle and, to a lesser extent, the mantles of Mars and Mercury which may be FeO rich and FeO-poor respectively. We use a least-squares minimization to optimise 4 model parameters. Elements currently considered include Si, O, Ni, Co, W, Nb, Cr, Ta and V. We concentrate on recent N-body simulations that result in an approximately Earth-mass planet at ~1 AU. In order to satisfy the model constraints, accretion has to be heterogeneous, with embryos and planetesimals originating in the inner part of the solar system (e.g. emulsify and equilibrate in a magma ocean and (2) the fraction of magma oceans that are involved in the equilibration process for both impacting planetesimals and embryos. Both estimates are crucial for interpreting Hf-W age determinations. Best results are obtained when the fraction of silicate mantle/magma ocean that interacts chemically with the metallic cores of impactors is limited and lies in the range 0.003 to 0.1, depending on the size of the impactor and magma ocean depth. The degree of incomplete metal equilibration depends on the extent to which the impactor's mantle participates in the metal-silicate equilibration process.

  12. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  13. High-pressure phase transitions in rare earth metal thulium to 195 GPa.

    Science.gov (United States)

    Montgomery, Jeffrey M; Samudrala, Gopi K; Tsoi, Georgiy M; Vohra, Yogesh K

    2011-04-20

    We have performed image plate x-ray diffraction studies on a heavy rare earth metal, thulium (Tm), in a diamond anvil cell to a pressure of 195 GPa and volume compression V/V₀ = 0.38 at room temperature. The rare earth crystal structure sequence, hcp →Sm-type→ dhcp →fcc → distorted fcc, is observed in Tm below 70 GPa with the exception of a pure fcc phase. The focus of our study is on the ultrahigh-pressure phase transition and Rietveld refinement of crystal structures in the pressure range between 70 and 195 GPa. The hexagonal hR-24 phase is seen to describe the distorted fcc phase between 70 and 124 GPa. Above 124 ± 4 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of -1.5%. The equation of state data shows rapid stiffening above the phase transition at 124 GPa and is indicative of participation of f-electrons in bonding. We compare the behavior of Tm to other heavy rare-earths and heavy actinide metals under extreme conditions of pressure.

  14. The atmospheric circulation of the super Earth GJ 1214b: Dependence on composition and metallicity

    CERN Document Server

    Kataria, Tiffany; Fortney, Jonathan J; Marley, Mark S; Freedman, Richard S

    2014-01-01

    We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean-molecular weight (i.e., H2-dominated) and a high mean-molecular weight (i.e. water- and CO2-dominated). We find that atmospheres with a low mean-molecular weight have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperature variations and hence stronger superrotation. In comparison, atmospheres with a high mean-molecular weight have larger day-night and equator-to-pole temperature variations than low mean-molecular weight atmospheres, but differences in opacity structure and energy budget lead ...

  15. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Han, M. K. [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe13-xSix system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb3Zn3.6Al7.4: Partially ordered structure of Tb3Zn3.6Al7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn39(CrxAl1-x)81

  16. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Han, Mi-Kyung [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe13-xSix system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn13-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb3Zn3.6Al7.4: Partially ordered structure of Tb3.6Zn13-xAl7.4 compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn39(CrxAl1-x

  17. Nano porous alkaline earth metal silicates as free fatty acid adsorbents from Crude Palm Oil (CPO)

    Science.gov (United States)

    Masmur, Indra; Sembiring, Seri Bima; Bangun, Nimpan; Kaban, Jamaran; Putri, Nabila Karina

    2017-01-01

    Free fatty acids(FFA) from Crude Palm Oil (CPO) have been adsorbed by alkaline earth metal silicate (M-silicate : M = Mg, Ca, Sr and Ba) adsorbents in ethanol using batch method. The adsorbents were prepared from the chloride salts of alkaline metals and Na2SiO3. The resulting white solid of the alkaline earth metal silicates were then heated at 800°C for 3 hours to enlarge their porosities. All adsorbents were characterized by SEM-EDX, XRD and BET. The EDX spectrum of SEM-EDX showed the appearance of all elements in the adsorbents, and the XRD spectrum of all adsorbents showed that they have crystobalite structure. The porosity of the adsorbents calculated by BET method showed that the porosities of the adsorbents range from 2.0884 - 2.0969 nm. All the adsorbents were used to adsorb the FFA from CPO containing 4.79%, 7.3%, 10.37% and 13.34% of FFA. The ratio of adsorbent to CPO to be used in adsorption of FFA from CPO were made 1:1, 1:2 and 1:3, with adsorption time of 1 hour. We found that the maximum adsorption of FFA from CPO was given by Ca-Silicate adsorbent which was between 69.86 - 94.78%, while the lowest adsorption was shown by Mg-silicate adsorbent which was 49.32 -74.53%.

  18. Ab Initio Calculation of 19F NMR Chemical Shielding for Alkaline-earth-metal Fluorides

    Institute of Scientific and Technical Information of China (English)

    CAI,Shu-Hui(蔡淑惠); CHEN,Zhong,(陈忠); LU,Xin(吕鑫); CHEN,Zhi-Wei(陈志伟); WAN,Hui-Lin(万惠霖)

    2001-01-01

    Gauge-independent atomic orbital (GIAO) method atHartree-Fock (HF) and density functional theory (DFr) lev-els,respectively,was employed to calculate 19F NMR chemi-cal shieldings of solid state alkaline-earth-metal fluorides MF2 (M = Mg,Ca,Sr,Ba).The results show that,although thecalculated19F chemical shieldings tend to be larger than the experinental values,they have a fairly good linear relation-ship with the observed ones.The calculated results based on different combinations of basis sets show that the B3LYP (ahybrid of DFT with HF) predictions are greatly superior tothe I-IF predictions.When a basis set of metal atom with ef- fecfive core potential (ECP) has well representation of valencewavefunction,especially wavefuncfion of d component,andproper definition of core electron nmnher,it can be applied toobtain 19F chemical shielding which is dose to that of all-elec-tron calculation.Tne variation of 19F chemical shielding of al-kaline-earth-metal fluorides correlates well with the latticefactor A/R2.``

  19. High-pressure metallization of FeO and implications for the earth's core

    Science.gov (United States)

    Knittle, Elise; Jeanloz, Raymond

    1986-01-01

    The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock-wave and diamond-cell techniques. A metallic phase of FeO is observed at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the earth's outer core, in accord with the geochemical predictions of Ringwood (1977 and 1979). The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core-forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions.

  20. Fabrication and Characterization of Glass-Ceramics Doped with Rare Earth Oxide and Heavy Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    陈国华; 刘心宇; 成钧

    2004-01-01

    Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO2) and heavy metal oxide (M2O3) respectively were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including compact density and apparent porosity, were examined to evaluate the sintering behavior of cordierite-based glass-ceramics. Results show that the additives both heavy metal oxide and rare earth oxide promote the sintering and lower the phase temperature from μ- to α-cordierite as well as affect the dielectric properties of sintered glass-ceramics. The complete-densification temperature for samples is as low as 900 ℃. The materials have a low dielectric constant (≈5), a low thermal expansion coefficient ((2.80~3.52)×10-6 ℃-1) and a low dissipation factor (≤0.2%) and can be co-fired with high conductivity metals such as Au, Cu, Ag/Pd paste at low temperature (below 950 ℃), which makes it to be a promising material for low-temperature co-fired ceramic substrates.

  1. Molecular heterometallic hydride clusters composed of rare-earth and d-transition metals.

    Science.gov (United States)

    Shima, Takanori; Luo, Yi; Stewart, Timothy; Bau, Robert; McIntyre, Garry J; Mason, Sax A; Hou, Zhaomin

    2011-09-18

    Heteromultimetallic hydride clusters containing both rare-earth and d-transition metals are of interest in terms of both their structure and reactivity. However, such heterometallic complexes have not yet been investigated to a great extent because of difficulties in their synthesis and structural characterization. Here, we report the synthesis, X-ray and neutron diffraction studies, and hydrogen addition and release properties of a family of rare-earth/d-transition-metal heteromultimetallic polyhydride complexes of the core structure type 'Ln(4)MH(n)' (Ln = Y, Dy, Ho; M = Mo, W; n = 9, 11, 13). Monitoring of hydrogen addition to a hydride cluster such as [{(C(5)Me(4)SiMe(3))Y}(4)(μ-H)(9)Mo(C(5)Me(5))] in a single-crystal to single-crystal process by X-ray diffraction has been achieved for the first time. Density functional theory studies reveal that the hydrogen addition process is cooperatively assisted by the Y/Mo heteromultimetallic sites, thus offering unprecedented insight into the hydrogen addition and release process of a metal hydride cluster.

  2. Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

    Science.gov (United States)

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-08-01

    Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

  3. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    Institute of Scientific and Technical Information of China (English)

    JIA You-Hun; ZHONG Biao; YIN Jian-Ping

    2009-01-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+-doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

  4. The contents of alkali and alkaline earth metals in soils of the southern Cis-Ural region

    Science.gov (United States)

    Asylbaev, I. G.; Khabirov, I. K.

    2016-01-01

    The contents and distribution patterns of alkali and alkaline earth metals in soils and rocks of the southern Cis-Ural region were studied. A database on the contents of these metals was developed, the soils were classified with respect to their provision with these metals, and corresponding schematic maps showing their distribution in soils of the region were compiled. It was found that the contents of these metals decrease from east to west (from the Yuryuzan-Aisk Piedmont Plain to the Ufa Plateau and to the Belebeevsk Upland), and their distribution patterns change. Among alkali metals, the highest accumulation in the soils is typical of potassium, sodium, and cesium; among alkaline earth metals, of strontium and barium.

  5. Processing of Phosphorus Slag with Recovery of Rare Earth Metals and Obtaining Silicon Containing Cake

    Science.gov (United States)

    Karshigina, Zaure; Abisheva, Zinesh; Bochevskaya, Yelena; Akcil, Ata; Sharipova, Aynash; Sargelova, Elmira

    2016-10-01

    The present research is devoted to the processing of slag generating during the yellow phosphorus production. In this paper are presented studies on leaching of phosphorus production slag by nitric acid with recovery of rare earth metals (REMs) into solution. REMs recovery into the solution achieved 98 % during the leaching process with using 7.5 mol/L of HNO3, liquid-to-solid ratio is 2.6:1, temperature is 60°C, process duration is 1 hour and stirrer speed is 500 rpm. Behaviour during the leaching of associated components such as calcium, aluminium, and iron was studied. After the leaching cake contains ∼⃒75-85 % of SiO2 and it might be useful for obtaining of precipitated silicon dioxide. With the purpose of separation from the impurities, recovery and concentrating of REMs, the obtained solution after leaching was subjected to extraction processing methods. The influence of ratio of organic and aqueous phases (O: A) on the extraction of rare earth metals by tributyl phosphate (TBP) with concentrations from 20 up to 100 % was studied. The REMs extraction with increasing TBP concentration under changes O:A ratio from 1:20 down to 1:1 into the organic phase from the solutions after nitric acid leaching increased from 22.2 up to 99.3%. The duration effect of REMs extraction process was studied by tributyl phosphate. It is revealed that with increasing of duration of the extraction process from 10 to 30 minutes REMs recovery into the organic phase almost did not changed. The behaviour of iron in the extraction process by TBP was studied. It was found that such accompanying components as calcium and aluminium by tributyl phosphate didn't extracted. To construct isotherm of REMs extraction of by tributyl phosphate was used variable volume method. It was calculated three-step extraction is needed for REMs recovery from the solutions after nitric acid leaching of phosphorus production slag. The process of the three-steps counter current extraction of rare earth

  6. EVALUATION OF RADIOLOGICAL SIGNIFICANCE OF RARE-EARTH METALS WITH NATURAL RADIOACTIVE ISOTOPES

    Directory of Open Access Journals (Sweden)

    E. P. Lisachenko

    2013-01-01

    Full Text Available Among the rare-earth metals with natural radioactive isotopes, lantan, lutetium and samarium are allocated a relatively high specific activity. The formation of the additional external radiation keep it close to the significance of the materials to the radiation categories of materials with a high content of natural radionuclides of uranium and thorium family, lanthanum value is much less. Samarium, with acceptable toxicology content in the working area, forms the internal exposure to the limits for professionals. The use of these elements in science and industry requires the radiation-hygienic evaluation.

  7. Narcissistic self-sorting in self-assembled cages of rare Earth metals and rigid ligands.

    Science.gov (United States)

    Johnson, Amber M; Wiley, Calvin A; Young, Michael C; Zhang, Xing; Lyon, Yana; Julian, Ryan R; Hooley, Richard J

    2015-05-04

    Highly selective, narcissistic self-sorting can be achieved in the formation of self-assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high-fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process.

  8. Preparation and mechanism study of bulk pure rare-earth metals with amorphous and nanocrystalline structures

    Institute of Scientific and Technical Information of China (English)

    LI ErDong; SONG XiaoYan; ZHANG JiuXing; LU NianDuan

    2007-01-01

    The preparation and the mechanism study of bulk pure rare-earth metals with amorphous and nanocrystalline structures, which were produced by spark plasma sintering (SPS), were carried out in this paper. With different processing parameters, the amorphous, two phases of amorphous and nanocrystalline, and complete nanocrystalline microstructures have been obtained. The nano-grain sizes in the bulk nanocrystalline materials are found smaller than the original powder particles sizes, which may change the conventional viewpoint that the grains in the sintered bulk are generally coarser than the raw powder particles. The technique developed in the present work can be extended to the preparation of many other nano bulk metal materials, and thus enables the studies of the nano-size effects on the physical, chemical and mechanical properties of bulk nano materials.

  9. 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.

  10. 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.

  11. Rare Earth Metal Complexes of Bidentate Nitroxide Ligands: Synthesis and Electrochemistry.

    Science.gov (United States)

    Kim, Jee Eon; Bogart, Justin A; Carroll, Patrick J; Schelter, Eric J

    2016-01-19

    We report rare earth metal complexes with tri- and bidentate ligands including strongly electron-donating nitroxide groups. The tridentate ligand 1,3,5-tris(2'-tert-butylhydroxylaminoaryl)benzene (H3arene-triNOx) was complexed to cerium(IV) in a 2:1 ligand-to-metal stoichiometry as Ce(Harene-triNOx)2 (1). Cyclic voltammetry of this compound showed stabilization of the tetravalent cerium cation with a Ce(IV/III) couple at E1/2 = -1.82 V versus Fc/Fc(+). On the basis of the uninvolvement of the third nitroxide group in the coordination chemistry with the cerium(IV) cation, the ligand system was redesigned toward a simpler bidentate mode, and a series of rare earth metal-arene-diNOx complexes were prepared with La(III), Ce(IV), Pr(III), Tb(III), and Y(III), [RE(arene-diNOx)2](-) ([2-RE](-), RE = La, Pr, Y, Tb) and Ce(IV)(arene-diNOx)2, where H2arene-diNOx = 1,3-bis(2'-tert-butylhydroxylaminoaryl)benzene. The core structures were isostructural throughout the series, with three nitroxide groups in η(2) binding modes and one κ(1) nitroxide group coordinated to the metal center in the solid state. In all cases except Ce(IV)(arene-diNOx)2, electrochemical analysis described two subsequent, ligand-based, quasi-reversible redox waves, indicating that a stable [N-O•] group was generated on the electrochemical time scale. Chemical oxidation of the terbium complex was performed, and isolation of the resulting complex, Tb(arene-diNOx)2·CH2Cl2 (3·CH2Cl2), confirmed the assignment of the cyclic voltammograms. Magnetic data showed no evidence of mixing between the Tb(III) states and the states of the open-shell ligand.

  12. METALLIC PHASE AND INSULATING CHARACTER OF ALKALI-EARTH METAL DOPED C60

    Institute of Scientific and Technical Information of China (English)

    曹阳; 陈良进; 陈波; 冯建文; 陈文建

    1995-01-01

    The three dimensional EHMO crystal orbital calculations for crystalline Ba6 C60,Ca3 C60 and Ca5 C60 are reported.The ground state of partially doped Ca3 C60 is found to be insulating with an indrect energy gap of 0.5eV.In contrast,the Ca5 C60 forms a metallic conducting phase with a set of three half-filled bands crossing the Fermi level which is Found to locate close to a peak of the density of state. The character of crystal orbitals near the Fermilevel for both Ca3 C60 and Ca5 C60 is completely carbon-like.In both cases the Ca3 atoms are almost fully ionized and C60 molecules form a stable negative charge state with six to ten additional electrons.The conductivity of Ba6 C60 is resuted from the incomplete charge tranfer.The valance charge of every Ba ion is about 0.33.The total charge tranfer of six Ba atoms is almost the same as that of five Ca atoms.

  13. Synthesis and Structures of A Series of Novel Rare Earth Transition Metal Sulfates

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Seven new rare earth transition metal sulfates were synthesized by hydrothermal reactions under conditions slightly above the critical point of water. Their crystal structures were determined from single crystal X-ray data. The compositions of the new compounds can be represented by two general formulae: REM(OH)3(SO4) and RE2M(OH)3(SO4)2F(H2O) with RE=Gd, Tb, Dy; M=Ni, Cu. Three different crystal structure types were found for the formula REM(OH)3(SO4). The structures of the new compounds all feature infinite chains of REOn coordination polyhedra, which are connected to chains of CuO6 or NiO6 octahedra. The limited size range of the rare earth cations observed in these compounds is most likely because of interactions between the octahedral chains and the chains of REOn polyhedra. The new compounds are closely related to the known yttrium transition metal sulfates.

  14. Long-range interacting many-body systems with alkaline-earth-metal atoms

    CERN Document Server

    Olmos, B; Singh, Y; Schreck, F; Bongs, K; Lesanovsky, I

    2012-01-01

    Alkaline-earth-metal atoms exhibit long-range dipolar interactions, which are generated via the coherent exchange of photons on the 3P_0-3D_1-transition of the triplet manifold. In case of bosonic strontium, which we discuss here, this transition has a wavelength of 2.7 \\mu m and a dipole moment of 2.46 Debye, and there exists a magic wavelength permitting the creation of optical lattices that are identical for the states 3P_0 and 3D_1. This interaction enables the realization and study of mixtures of hard-core lattice bosons featuring long-range hopping, with tuneable disorder and anisotropy. We derive the many-body Master equation, investigate the dynamics of excitation transport and analyze spectroscopic signatures stemming from coherent long-range interactions and collective dissipation. Our results show that lattice gases of alkaline-earth-metal atoms permit the creation of long-lived collective atomic states and constitute a simple and versatile platform for the exploration of many-body systems with lon...

  15. Selective Uptake of Alkaline Earth Metals by Cyanobacteria Forming Intracellular Carbonates.

    Science.gov (United States)

    Cam, Nithavong; Benzerara, Karim; Georgelin, Thomas; Jaber, Maguy; Lambert, Jean-François; Poinsot, Mélanie; Skouri-Panet, Fériel; Cordier, Laure

    2016-11-01

    The uptakes of calcium (Ca), strontium (Sr), and barium (Ba) by two cyanobacterial strains, Cyanothece sp. PCC7425 and Gloeomargarita lithophora, both forming intracellular carbonates, were investigated in laboratory cultures. In the culture medium BG-11 amended with 250 μM Ca and 50 or 250 μM Sr and Ba, G. lithophora accumulated first Ba, then Sr, and finally Ca. Sr and Ba were completely accumulated by G. lithophora cells at rates between 0.02 and 0.10 fmol h(-1) cell(-1) and down to extracellular concentrations below the detection limits of inductively coupled plasma atomic emission spectroscopy. Accumulation of Sr and Ba did not affect the growth rate of the strain. This sequential accumulation occurred mostly intracellularly within polyphosphate and carbonate granules and resulted in the formation of core-shell structures in carbonates. In contrast, Cyanothece sp. PCC7425 showed neither a preferential accumulation of heavier alkaline earth metals nor core-shell structures in the carbonates. This indicated that fractionation between alkaline earth metals was not inherent to intracellularly calcifying cyanobacteria but was likely a genetically based trait of G. lithophora. Overall, the capability of G. lithophora to sequester preferentially Sr and Ba at high rates may be of considerable interest for designing new remediation strategies and better understanding the geochemical cycles of these elements.

  16. Earthshine observations at high spectral resolution: Exploring and detecting metal lines in the Earth's upper atmosphere

    CERN Document Server

    González-Merino, B; Motalebi, F; Montañés-Rodríguez, P; Kissler-Patig, M

    2013-01-01

    Observations of the Earth as a planet using the earthshine technique (i.e. looking at the light reflected from the darkside of the Moon), have been used for climate and astrobiology studies. They provide information about the planetary albedo, a fundamental parameter of the Earth's energy balance. Here we present for the first time, observations of the earthshine taken at high spectral resolution. The high spectral resolution was chosen in order to investigate the possibility of detecting metallic layers in the Earth's atmosphere of geological or meteoritic origin. The SARG echelle spectrograph at the Telescopio Nazionale Galileo in La Palma was used to acquire the earthshine data. Observations were carried out on several nights in February 2011, with the spectral resolution set at 29,000, covering a spectral range from the near-ultraviolet (360 nm) to near-infrared (1011.9 nm). While we find evidence for the detection of a Na layer in the earthshine, other atomic species are not detected, perhaps due to the ...

  17. Crystal Morphologies of Organolead Trihalide in Mesoscopic/Planar Perovskite Solar Cells.

    Science.gov (United States)

    Zhou, Yuanyuan; Vasiliev, Alexander L; Wu, Wenwen; Yang, Mengjin; Pang, Shuping; Zhu, Kai; Padture, Nitin P

    2015-06-18

    The crystal morphology of organolead trihalide perovskite (OTP) light absorbers can have profound influence on the perovskite solar cells (PSCs) performance. Here we have used a combination of conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), in cross-section and plan-view, to characterize the morphologies of a solution-processed OTP (CH3NH3PbI3 or MAPbI3) within mesoporous TiO2 scaffolds and within capping and planar layers. Studies of TEM specimens prepared with and without the use of focused ion beam (FIB) show that FIBing is a viable method for preparing TEM specimens. HRTEM studies, in conjunction with quantitative X-ray diffraction, show that MAPbI3 perovskite within mesoporous TiO2 scaffold has equiaxed grains of size 10-20 nm and relatively low crystallinity. In contrast, the grain size of MAPbI3 perovskite in the capping and the planar layers can be larger than 100 nm in our PSCs, and the grains can be elongated and textured, with relatively high crystallinity. The observed differences in the performance of planar and mesoscopic-planar hybrid PSCs can be attributed in part to the striking differences in their perovskite-grain morphologies.

  18. Tidal Downsizing Model. III. Planets from sub-Earths to Brown Dwarfs: structure and metallicity preferences

    CERN Document Server

    Nayakshin, Sergei

    2015-01-01

    We present improved population synthesis calculations in the context of the Tidal Downsizing (TD) hypothesis for planet formation. Our models provide natural explanations and/or quantitative match to exoplanet observations in the following categories: (i) most abundant planets being super-Earths; (ii) cores more massive than $\\sim 5-15 M_\\oplus$ are enveloped by massive metal-rich atmospheres; (iii) the frequency of occurrence of close-in gas giant planets correlates strongly with metallicity of the host star; (iv) no such correlation is found for sub-Neptune planets; (v) presence of massive cores in giant planets; (vi) the composition of gas giant planets is over-abundant in metals compared to their host stars; (vii) this over-abundance decreases with planet's mass, as observed; (viii) a deep valley in the planet mass function between masses of $\\sim 10-20 M_\\oplus$ and $\\sim 100 M_\\oplus$. We provide a number of observational predictions distinguishing the model from Core Accretion: (a) composition of the m...

  19. Influence of Rare Earth Metals on Microstructure and Inclusions Morphology G17CrMo5-5 Cast Steel

    Directory of Open Access Journals (Sweden)

    Kasińska J.

    2014-10-01

    Full Text Available This paper presents influence of rare earth metals (REM on the microstructure and morphology of non-metallic inclusions of G17CrMo5-5 cast carbon steel The research has been performed on successive industrial melts. Each time about 2000 kg of liquid metal was modified. The REM was in the form of mishmetal of the composition 49, 8% Ce, 21, 8% La, 17, 1% Nd, 5, 5% Pr and 5, 35% the rest of REM. Therareearth metals were put into the ladle during tapping of heat melt from the furnace.

  20. Technique for recovering rare-earth metals from spent sintered Nd-Fe-B magnets without external heating

    Directory of Open Access Journals (Sweden)

    Ryo Sasai

    2016-06-01

    Full Text Available To selectively recover rare-earth metals with higher purity from spent sintered Nd-Fe-B magnets without external heating, we investigated the mechano-chemical treatment of spent sintered Nd-Fe-B magnet powder with a reaction solution of HCl and (COOH2 at room temperature. The results of various experiments showed that the mechano-chemical treatment with HCl and (COOH2 is very effective for recovering the rare-earth metals contained in spent sintered Nd-Fe-B magnet powder; the recovery rate and purity of the rare-earth metals were 95.3 and 95.0 mass%, respectively, under optimal conditions ([HCl] = 0.2 mol/dm3 and [(COOH2] = 0.25 mol/dm3.

  1. Energetics and bonding in aluminosilicate rings with alkali metal and alkaline-earth metal charge-compensating cations.

    Science.gov (United States)

    Gatti, Carlo; Ottonello, Giulio; Richet, Pascal

    2012-08-23

    The stabilizing effect of alkali and alkaline-earth metal ions on the oxygen donors of four- and six-membered faujausite-like rings has been calculated in terms of Kohn-Sham core-level (O1s) energy shifts with respect to these same complexes without cations. The results confirm and complement earlier investigations by Vayssilov and co-workers where Na(+) and K(+) were the only complexing cations. The oxygen donor centers in six-membered rings are stabilized by -3.6 ± 0.4, -3.9 ± 0.5, -7.3 ± 0.1, and -7.6 ± 0.2 eV by K(+), Na(+), Ca(2+), and Mg(2+) adions, respectively. The energy shifts are even greater for four-membered rings where the stabilization effects attain -3.7 ± 0.1, -4.1 ± 0.1, -8.1 ± 0.1, and -9.0 ± 0.1 eV, respectively. These effects are also observed on the low-lying σ-bonding and antibonding molecular orbitals (MOs) of the oxygen framework, but in a less systematic fashion. Clear relationships with the core-level shifts are found when the effects of alkali metal complexation are evaluated through electron localization/delocalization indices, which are defined in terms of the whole wave function and not just of the individual orbitals. Complexation with cations not only involves a small but significant electron sharing of the cation with the oxygen atoms in the ring but also enhances electron exchange among oxygen atoms while reducing that between the O atoms and the Si or Al atoms bonded to them. Such changes slightly increase from Na to K and from Mg to Ca, whereas they are significantly enhanced for alkaline-earth metals relative to alkali metals. With respect to Al-free complexes, Si/Al substitution and cation charge compensation generally enhance electron delocalization among the O atoms, except between those that are linked through an Al atom, and cause either an increased or a decreased Si-O ionicity (smaller/higher electron exchange) depending on the position of O in the chain relative to the Al atom(s). The generally increased

  2. Liquid-liquid extraction and separation of total rare earth (RE) metals from polymetallic manganese nodule leaching solution

    Institute of Scientific and Technical Information of China (English)

    PK Parhi; KH Park; CW Nam; JT Park

    2015-01-01

    The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca(OH)2 at pH 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents (D2EHPA, PC88A, Cyanex 272) were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. pH effect, the performances of above three extractants followed the order as:D2EHPA>PC88A>Cyanex 272. To ensure the absence of extraction of base metals (Cu, Co, Ni), the eq. pH of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. pH with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2EHPA. Extraction isotherm plot was constructed at A:O=12:1, 3-stages and pHe=2.21, using 0.8 mol/L D2EHPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current Simulation (CCS) study. The stripping of total rare earth from loaded organic phase (LO) was conducted using HCl solution. Mc-Cabe Thiele diagram study carried out at A:O=1:5 using 4 mol/L HCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction (SX) process.

  3. Imidazolin-2-iminato complexes of rare earth metals with very short metal-nitrogen bonds: experimental and theoretical studies.

    Science.gov (United States)

    Panda, Tarun K; Trambitas, Alexandra G; Bannenberg, Thomas; Hrib, Cristian G; Randoll, Sören; Jones, Peter G; Tamm, Matthias

    2009-06-15

    The reactions of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH, 1-H) with trimethylsilylmethyl lithium (LiCH(2)SiMe(3)) and anhydrous rare earth metal trichlorides MCl(3) afforded the imidazolin-2-iminato complexes [(1)MCl(2)(THF)(3)] (2a, M = Sc; 2b, M = Y; 2c, M = Lu) and [(1)GdCl(2)(THF)(2)] x [LiCl(THF)(2)] (2d). Treatment of complexes 2 with dipotassium cyclooctatetradienide, K(2)(C(8)H(8)) resulted in the formation of two- or three-legged piano-stool complexes of the type [(eta(8)-C(8)H(8))M(1)(THF)(n)] (3a, M = Sc, n = 1; 3b, M = Y, n = 2; 3c, M = Lu, n = 2; 3d, M = Gd, n = 2). X-ray diffraction analyses of all eight complexes 2 and 3 revealed the presence of very short metal-nitrogen bonds, which are among the shortest ever observed for these elements. [(eta(8)-C(8)H(8))Sc(1)(THF)] (3a) reacted with 2,6-dimethylphenyl isothiocyanate (Xy-NCS) to form the [2 + 2]-cycloaddition product 4, which contains a thioureato-N,N' moiety. The related COT-titanium complex [(eta(8)-C(8)H(8))TiCl(1)] (6) could be obtained from [(1)TiCl(3)] (5) by reaction with K(2)(C(8)H(8)) and was structurally characterized. As a theoretical analysis of the nature of the metal-nitrogen bond, density functional theory (DFT) calculations have been carried out for complexes 3a and 6 and also for the model complexes [(eta(8)-C(8)H(8))Sc(NIm(Me))] (7), [(eta(8)-C(8)H(8))Ti(NIm(Me))](+) (8), and [(eta(8)-C(8)H(8))Ti(NXy)] (9), revealing a marked similarity of the bonding in imidazolin-2-iminato and conventional imido metal complexes.

  4. Electric dipole polarizability of alkaline-Earth-metal atoms from perturbed relativistic coupled-cluster theory with triples

    CERN Document Server

    Chattopadhyay, S; Angom, D

    2014-01-01

    The perturbed relativistic coupled-cluster (PRCC) theory is applied to calculate the electric dipole polarizabilities of alkaline Earth metal atoms. The Dirac-Coulomb-Breit atomic Hamiltonian is used and we include the triple excitations in the relativistic coupled-cluster (RCC) theory. The theoretical issues related to the triple excitation cluster operators are described in detail and we also provide details on the computational implementation. The PRCC theory results are in good agreement with the experimental and previous theoretical results. We, then, highlight the importance of considering the Breit interaction for alkaline Earth metal atoms.

  5. New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars

    CERN Document Server

    Sneden, Christopher; Cowan, John J; Ivans, Inese I; Hartog, Elizabeth A Den

    2009-01-01

    We have derived new abundances of the rare-earth elements Pr, Dy, Tm, Yb, and Lu for the solar photosphere and for five very metal-poor, neutron-capture r-process-rich giant stars. The photospheric values for all five elements are in good agreement with meteoritic abundances. For the low metallicity sample, these abundances have been combined with new Ce abundances from a companion paper, and reconsideration of a few other elements in individual stars, to produce internally-consistent Ba, rare-earth, and Hf (56<= Z <= 72) element distributions. These have been used in a critical comparison between stellar and solar r-process abundance mixes.

  6. Strategic design and refinement of Lewis acid-base catalysis by rare-earth-metal-containing polyoxometalates.

    Science.gov (United States)

    Suzuki, Kosuke; Sugawa, Midori; Kikukawa, Yuji; Kamata, Keigo; Yamaguchi, Kazuya; Mizuno, Noritaka

    2012-06-18

    Efficient polyoxometalate (POM)-based Lewis acid-base catalysts of the rare-earth-metal-containing POMs (TBA(6)RE-POM, RE = Y(3+), Nd(3+), Eu(3+), Gd(3+), Tb(3+), or Dy(3+)) were designed and synthesized by reactions of TBA(4)H(4)[γ-SiW(10)O(36)] (TBA = tetra-n-butylammonium) with RE(acac)(3) (acac = acetylacetonato). TBA(6)RE-POM consisted of two silicotungstate units pillared by two rare-earth-metal cations. Nucleophilic oxygen-enriched surfaces of negatively charged POMs and the incorporated rare-earth-metal cations could work as Lewis bases and Lewis acids, respectively. Consequently, cyanosilylation of carbonyl compounds with trimethylsilyl cyanide ((TMS)CN) was efficiently promoted in the presence of the rare-earth-metal-containing POMs via the simultaneous activation of coupling partners on the same POM molecules. POMs with larger metal cations showed higher catalytic activities for cyanosilylation because of the higher activation ability of C═O bonds (higher Lewis acidities) and sterically less hindered Lewis acid sites. Among the POM catalysts examined, the neodymium-containing POM showed remarkable catalytic performance for cyanosilylation of various kinds of structurally diverse ketones and aldehydes, giving the corresponding cyanohydrin trimethylsilyl ethers in high yields (13 substrates, 94-99%). In particular, the turnover frequency (714,000 h(-1)) and the turnover number (23,800) for the cyanosilylation of n-hexanal were of the highest level among those of previously reported catalysts.

  7. Thermodynamics analysis of the rare earth metals and their alloys with indium in solid state

    Energy Technology Data Exchange (ETDEWEB)

    Vassiliev, V.P., E-mail: valeryvassiliev@yahoo.fr [Chemical Department, Lomonossov University, Moscow 119992 (Russian Federation); Benaissa, Ablazeze [Département des Matériaux, Faculté des Sciences de l’Ingénieur, Université M’hamed Bougara, Boumerdes 35000 (Algeria); Taldrik, A.F. [Institute of Superconductivity and Solid State Physics, Academician Kurchatov 1, Moscow 123098 (Russian Federation)

    2013-09-25

    Graphical abstract: Gibbs energies of formation vs. RE atomic numbers in REIn{sub 3}. Highlights: •Set of experimental values was collected for REIn{sub 3} phases. •Thermodynamic functions of formation were calculated at 298 K and 775 K. •Experimental and calculated values were compared. -- Abstract: Nonlinear correlative analyses between thermodynamic and some physico-chemical properties of rare-earth metals (RE) and their alloys with indium are performed for the isostructural phases RE and REIn{sub 3}. The thermodynamics values (Gibbs energies of formation, enthalpies of formation, and entropies of formation at 298 K and 775 K and standard entropies) of LnIn{sub 3} phases are calculated on the basis of calorimetry and potentiometry results. The proposed correlation between physico-chemical and thermodynamic properties agrees for all the isostructural phases REX (X are others elements of the periodic table). The resulting thermodynamic data are recommended for metallurgical handbook.

  8. Linear alkaline earth metal phosphinate coordination polymers: synthesis and structural characterization.

    Science.gov (United States)

    Rood, Jeffrey A; Huttenstine, Ashley L; Schmidt, Zachery A; White, Michael R; Oliver, Allen G

    2014-06-01

    Reaction of alkaline earth metal salts with diphenylphosphinic acid in dimethylformamide solvent afforded four coordination polymers: [Mg3(O2PPh2)6(DMF)2]·2DMF (I), [Ca(O2PPh2)2(DMF)2] (II), [Sr(O2PPh2)2(DMF)2] (III) and [Ba(O2PPh2)2(DMF)2] (IV) (where DMF is N,N-dimethylformamide). Single-crystal X-ray diffraction revealed that all four compounds produce linear chain structures in the solid state, with the Ca, Sr and Ba forming isostructural crystals. The bulk materials were characterized by FT-IR and (1)H NMR spectroscopy and elemental analyses.

  9. Coordination Polymerization of Renewable 3-Methylenecyclopentene with Rare-Earth-Metal Precursors.

    Science.gov (United States)

    Liu, Bo; Li, Shihui; Wang, Meiyan; Cui, Dongmei

    2017-04-10

    Coordination polymerization of renewable 3-methylenecyclopentene has been investigated for the first time using rare-earth metal-based precursors bearing various bulky ligands. All the prepared complexes catalyze controllable polymerization of 3-methylenecyclopentene into high molecular weight polymers, of which the NPN- and NSN-tridentate non-Cp ligated lutetium-based catalytic systems exhibited extremely high activities up to 11 520 kg/(molLu ⋅h) in a dilute toluene solution (3.2 g/100 mL) at room temperature. The resultant polymers have pure 1,4-regioregularity (>99 %) and tailorable number average molecular weights (1-20×10(4) ) with narrow molecular weight distributions (polydispersity index (PDI)=1.45-1.79). DFT simulations were employed to study the polymerization mechanism and stereoregularity control. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. 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-spin......1-xCox durch ein einfaches Model1 erklärt werden können, das eine RKKY-Wechsel-wirkung zwischen den Momenten der Seltenen Erden und des Pseudo-Spins des Übergangsmetalls annimmt. Die Wechselwirkung wird durch ein effektives Legierungsmedium übermittelt, das mit der CPA-Theorie und elliptischen...

  11. 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.

  12. Recording experiments on rare-earth transition-metal thin films studied with Lorentz microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Greidanus, F.J.A.M.; Jacobs, B.A.J.; Spruit, J.H.M. (Philips Research Labs., Eindhoven (Netherlands)); Klahn, S. (Philips GmbH Forschungslaboratorium Hamburg, D-2000 Hamburg (DE))

    1989-09-01

    Domains written thermomagnetically under recording conditions in rare-earth transition-metal thin films are studied with Lorentz microscopy. New technique in which the magneto-optical layer is deposited on specially prepared silicon wafer disks, provided with Si/sub 3/N/sub 4/ windows is described. This technique allows direct observation of the written domain patterns in the electron microscope. It is demonstrated that the nucleation process plays a crucial role when writing in TbFeCo. Different compositions, having different temperature dependencies of the magnetic properties, lead to remarkably different domain-formation behaviour. With the detailed insight into the shape and structure of domains obtained by Lorentz microscopy, carrier and noise levels obtained from recording experiments can be understood. This is demonstrated with data on GdTbFe. It is shown that magnetic-field modulation, apart from the advantage of direct overwrite, offers the possibility of very high density recording.

  13. Structures of rare earth-transition metal rich compounds derived from CaCu5 type

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The properties of materials have a close connect ion to their crystal structures. Rare earth (R)-transition metal (T) rich compo und are the focus of investigation in the search for new hard magnetic materials . As the basis for the study of stabilized effect of the third component on the fo rmation of RT5 derivative and its influence of the occupied sites on magnetic properties, in this paper, the possible derivative compounds based on the RT5 primitive unit cell of the CaCu5 structure type formed through the ordered or disordered substitution of dumbbell pair 2T atoms for the R atoms at some sit es, and the structural relationship between the derivatives and the prototype ar e summarized.

  14. Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

    Science.gov (United States)

    Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; Vohra, Yogesh K.

    2014-04-01

    Magnetic ordering temperatures in heavy rare earth metal dysprosium (Dy) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to a pressure of 69 GPa and a temperature of 10 K. Previous studies using magnetic susceptibility measurements at high pressures were able to track magnetic ordering temperature only till 7 GPa in the hexagonal close packed (hcp) phase of Dy. Our studies indicate that the magnetic ordering temperature shows an abrupt drop of 80 K at the hcp-Sm phase transition followed by a gradual decrease that continues till 17 GPa. This is followed by a rapid increase in the magnetic ordering temperatures in the double hcp phase and finally leveling off in the distorted face centered cubic phase of Dy. Our studies reaffirm that 4f-shell remains localized in Dy and there is no loss of magnetic moment or 4f-shell delocalization for pressures up to 69 GPa.

  15. Alkaline-earth metal hydrides as novel host lattices for Eu(II) luminescence.

    Science.gov (United States)

    Kunkel, Nathalie; Kohlmann, Holger; Sayede, Adlane; Springborg, Michael

    2011-07-04

    Luminescence of divalent europium has been investigated for the first time in metal hydrides. A complete solid-solution series was found for the pseudobinary system Eu(x)Sr(1-x)H(2) [a = 637.6(1) pm -12.1(3)x pm, b = 387.0(1)-6.5(2)x pm, c = 732.2(2)-10.1(4)x pm]. Europium-doped alkaline-earth hydrides Eu(x)M(1-x)H(2) (M = Ca, Sr, Ba) with a small europium concentration (x = 0.005) exhibit luminescence with maximum emission wavelengths of 764 nm (M = Ca), 728 nm (M = Sr), and 750 nm (M = Ba); i.e., the emission energy of divalent europium shows an extremely large red shift compared to the emission energies of fluorides or oxides. Theoretical calculations (LDA+U) confirm decreasing band gaps with increasing europium content of the solid solutions.

  16. Spin-orbit qubits of rare-earth-metal ions in axially symmetric crystal fields.

    Science.gov (United States)

    Bertaina, S; Shim, J H; Gambarelli, S; Malkin, B Z; Barbara, B

    2009-11-27

    Contrary to the well-known spin qubits, rare-earth-metal qubits are characterized by a strong influence of crystal field due to large spin-orbit coupling. At low temperature and in the presence of resonance microwaves, it is the magnetic moment of the crystal-field ground state which nutates (for several micros) and the Rabi frequency Omega(R) is anisotropic. Here, we present a study of the variations of Omega(R)(H(0)) with the magnitude and direction of the static magnetic field H(0) for the odd 167Er isotope in a single crystal CaWO(4):Er(3+). The hyperfine interactions split the Omega(R)(H(0)) curve into eight different curves which are fitted numerically and described analytically. These "spin-orbit qubits" should allow detailed studies of decoherence mechanisms which become relevant at high temperature and open new ways for qubit addressing using properly oriented magnetic fields.

  17. Synthesis of monomeric and polymeric alkali and alkaline earth metal complexes using a phosphinoselenoic amide ligand in metal coordination sphere

    Indian Academy of Sciences (India)

    Jayeeta Bhattacharjee; Ravi K Kottalanka; Harinath Adimulam; Tarun K Panda

    2014-09-01

    We report the monomeric complexes of magnesium and calcium of composition [M(THF){2-Ph2P(Se)N(CMe3)}2] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)2{Ph2P(Se)N(CMe3)}] (2) and [K(THF)Ba{Ph2P(Se)N(CMe3)}3](5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg2+ (0.72Å) and Ca2+ (0.99Å) ions form the monomeric complex, whereas the larger ions K+ (1.38Å) and Ba2+ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

  18. Binding and selectivity of phenazino-18-crown-6-ether with alkali, alkaline earth and toxic metal species: A DFT study

    Science.gov (United States)

    Islam, Nasarul; Chimni, Swapandeep Singh

    2017-02-01

    The interactions of phenazino-crown ether ligands with alkali, alkaline earth and selected toxic species were investigated using density functional theory modelling by employing B3PW91/6-311G ++ (d, p) level of theory. The complex stability was analysed in terms of binding energies, perturbation energies, position of highest molecular orbital and energy gap values. In general, the complexes formed by P18C6-1a ligand with metal cations were found to be more stable than those with P18C6-1b. Among alkali and alkaline earth metals complexes having highest stability was observed for the complex formed by P18C6-1a with Be2+. Computational calculations of P18C6 ligand with toxic metal ions reveals that the P18C6-Cr6+ metal complexes acquire envelop like geometry, leading to higher binding energy values. Comparing the binding energies of neutral and monocations of Ag and Hg, the former had higher value both in neutral as well as monocation state. Thus, the stability of metal complexes is determined not only by the ligand but also by the type of metal ion. In solvent systems the stability constants of metal complexes were found increasing with decreasing permittivity of the solvent. This reflects the inherited polar character of the protic solvents stabilises the cation, resulting in decrease of effective interaction of ligand with the metal ion.

  19. 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.

  20. pH-metric and thermodynamic studies of rare earth metal chelates

    Institute of Scientific and Technical Information of China (English)

    Alok Vyas; R. P. Mathur

    2009-01-01

    Proton ligand stability constants of hydroxybenzoic acid containing nitro group (2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid) were determined through Irving-Rossoti pH titration technique. The stability constants of rare earth metal chelates con-taining 2-Hydroxy-4-nitrobenzoic acid and 3-Hydroxy-4-nitrobenzoic acid as ligands were studied in aqueous medium at different ionic strength (μ=0.01, 0.05 and 0.1 mol/L) and temperatures (298, 308 and 318±0.1 K). The values of stability constant were evaluated through different computational methods like successive approximation, least square treatment, correction term method, and convergence method. The observed value of thermodynamic parameters (△G°, △H° and △S°) favors the complex formation between metal and ligands. The order of stability constant was found to be Pr(Ⅲ)

  1. Syntheses, structure and properties of Alkaline-earth metal salts of 4-Nitrophenylacetic acid

    Indian Academy of Sciences (India)

    BIKSHANDARKOIL R SRINIVASAN; KIRAN T DHAVSKAR; CHRISTIAN NÄTHER

    2016-11-01

    The synthesis, crystal structure, spectral characteristics and thermal properties of alkaline-earth metal salts of 4-nitrophenylacetic acid (4-npaH) namely, [Mg(H₂O)₆](4-npa)₂·4H₂O (4-npa = 4-nitrophenylacetate) (1), [Ca(H₂O)₂(4-npa)₂] (2) and [Sr(H₂O)₃(4-npa)₂]·4.5H₂O(3) are reported. In 1, the 4-npa ion functions as a charge balancing counter anion for the octahedral [Mg(H₂O)6]²⁺ unit with the Mg(II) ion situated on a centre of inversion. The two unique lattice water molecules link the [Mg(H₂O)₆]²⁺ cations and 4-npa anions with the aid of O-H· · ·O interactions. Compounds 2 and 3 are one-dimensional (1-D) coordination polymers containing an eight coordinated Ca(II) situated in a general position and a nine coordinated Sr(II) located on a twofold axis. The μ₂-bridging tridentate binding modes of the crystallographically independent 4-npa ligands in 2 and the unique 4-npa ligand in 3 link the bivalent metal ions into an infinite chain with alternating Ca· · · Ca separations of 3.989 and 4.009 Å, respectively, and a single Sr· · · Sr separation of 4.194Å in the 1-D chain.

  2. Nitridomanganates of alkaline-earth metals. Synthesis, structure, and physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, Alexander

    2016-12-02

    The main goal of the present work was the synthesis of alkaline-earth nitridomanganates (AE{sub x}Mn{sub y}N{sub z}) with extended anionic structures and the characterization of their electronic and magnetic properties. Up to now, only compounds with isolated nitridomanganate anions have been reported in the discussed ternary systems. A systematic exploratory synthesis, employing high-temperature treatment of AE nitrides and Mn under controlled N2 pressure, yielded more than ten new nitridomanganates. Their crystal structures contain anionic building blocks of different dimensionalities, ranging from isolated species to three-dimensional frameworks. In general, the formation of Mn-rich compositions was found to be driven by the emergence of Mn-Mn interactions, which creates a link between nitridometalates and transition-metal-rich binary nitrides. The obtained nitridomanganates display a plethora of interesting phenomena, such as large spin-orbit coupling, magnetic frustration, quenching of magnetism due to Mn-Mn interactions, and metal-insulator transition.

  3. Effects of rare earth oxide on hardfacing metal microstructure of medium carbon steel and its refinement mechanism

    Institute of Scientific and Technical Information of China (English)

    HAO Feifei; LIAO Bo; LI Da; LIU Ligang; DAN Ting; REN Xuejun; YANG Qingxiang

    2011-01-01

    The electrodes for hardfacing medium carbon steel with six additions of rare earth oxide were developed in this work. By means of optical microscopy and scanning electron microscopy, the microstructure, inclusion and the fractograph of the hardfacing metal were observed. Then, the effects of rare earth oxide on microstructure and inclusions in hardfacing metal were analyzed. The effectiveness of rare earth oxide as heterogeneous nuclei of δ-Fe was calculated with the misfit theory. The results showed that, the microstructure of hardfacing metal was composed of ferrite and small amount of pearlite. The microstructure was refined at first and then coarsened with the increase of rare earth oxide addition. The fractograph was changed from brittle to equiaxed dimples, then became quasi-cleavage and cleavage gradually.The calculated results showed that, the ferrite grain size could be refined because that LaA1O3 as heterogeneous nuclei ofδ-Fe was moderately effective, and the ferrite grain size was coarsened because the misfits between Ce2O3 and δ-Fe, Ce2O2S and δ-Fe were increased with futher increase of rare earth oxide addition.

  4. Heterogeneous Earth Accretion and Incomplete Metal-Silicate Reequilibration at High Pressure During Core Formation

    Science.gov (United States)

    Rubie, D. C.; Mann, U.; Frost, D. J.; Kegler, P.; Holzheid, A.; Palme, H.

    2007-12-01

    We present a new model of core formation, based on the partitioning of siderophile elements, that involves accreting the Earth through a series of collisions with smaller bodies that had already differentiated at low pressure. Each impact results in a magma ocean in which the core of the impactor reequilibrates with silicate liquid at high pressure before merging with the Earth's protocore. The oxygen contents of the chondritic compositions of the proto-Earth and impactors can be varied. The compositions of coexisting metal and silicate are determined through mass balance combined with partitioning equations for Ni, FeO, Si and other siderophile elements. The oxygen fugacity is fixed by the partitioning of FeO and is a function of P, T and bulk oxygen content. An important constraint for core formation is that core-mantle partition coefficients for Ni and Co must both converge to values of 23-28. Based on a recent study of the partitioning of Ni and Co over a wide P-T range (Kegler et al., EPSL, submitted) together with other published data, this constraint is not satisfied by a single- stage core formation model at any conditions because the partition coefficients converge at values that are much too low. In the present multi-stage model, the correct values can be reached if only part of each impactor core reequilibrates with silicate liquid in the magma ocean (as proposed by previous models based on Hf-W isotope studies). Physically, this would mean that impactor cores fail to emulsify completely as they sink through the magma ocean. Incorporating other elements (e.g. V and Cr) in the model requires, in addition, that the bulk composition of the impactors changes during accretion from reduced (FeO-poor) to oxidised FeO-rich). Then, with the resulting increase in fO2, incomplete reequilibration of the cores during the final 20-30% of Earth accretion is required to satisfy the Ni-Co constraint. In addition, this model enables the concentrations of O and Si in the

  5. Bis(imidazolin-2-iminato) rare earth metal complexes: synthesis, structural characterization, and catalytic application.

    Science.gov (United States)

    Trambitas, Alexandra G; Melcher, Daniel; Hartenstein, Larissa; Roesky, Peter W; Daniliuc, Constantin; Jones, Peter G; Tamm, Matthias

    2012-06-18

    Reaction of anhydrous rare earth metal halides MCl(3) with 2 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) and 2 equiv of trimethylsilylmethyl lithium (Me(3)SiCH(2)Li) in THF furnished the complexes [(Im(Dipp)N)(2)MCl(THF)(n)] (M = Sc, Y, Lu). The molecular structures of all three compounds were established by single-crystal X-ray diffraction analyses. The coordination spheres around the pentacoordinate metal atoms are best described as trigonal bipyramids. Reaction of YbI(2) with 2 equiv of LiCH(2)SiMe(3) and 2 equiv of the imino ligand Im(Dipp)NH in tetrahydrofuran did not result in a divalent complex, but instead the Yb(III) complex [(Im(Dipp)N)(2)YbI(THF)(2)] was obtained and structurally characterized. Treatment of [(Im(Dipp)N)(2)MCl(THF)(n)] with 1 equiv of LiCH(2)SiMe(3) resulted in the formation of [(Im(Dipp)N)(2)M(CH(2)SiMe(3))(THF)(n)]. The coordination arrangement of these compounds in the solid state at the metal atoms is similar to that found for the starting materials, although the introduction of the neosilyl ligand induces a significantly greater distortion from the ideal trigonal-bipyramidal geometry. [(Im(Dipp)N)(2)Y(CH(2)SiMe(3))(THF)(2)] was used as precatalyst in the intramolecular hydroamination/cyclization reaction of various terminal aminoalkenes and of one aminoalkyne. The complex showed high catalytic activity and selectivity. A comparison with the previously reported dialkyl yttrium complex [(Im(Dipp)N)Y(CH(2)SiMe(3))(2)(THF)(3)] showed no clear tendency in terms of activity.

  6. Silylation of C-H bonds in aromatic heterocycles by an Earth-abundant metal catalyst

    Science.gov (United States)

    Toutov, Anton A.; Liu, Wen-Bo; Betz, Kerry N.; Fedorov, Alexey; Stoltz, Brian M.; Grubbs, Robert H.

    2015-02-01

    Heteroaromatic compounds containing carbon-silicon (C-Si) bonds are of great interest in the fields of organic electronics and photonics, drug discovery, nuclear medicine and complex molecule synthesis, because these compounds have very useful physicochemical properties. Many of the methods now used to construct heteroaromatic C-Si bonds involve stoichiometric reactions between heteroaryl organometallic species and silicon electrophiles or direct, transition-metal-catalysed intermolecular carbon-hydrogen (C-H) silylation using rhodium or iridium complexes in the presence of excess hydrogen acceptors. Both approaches are useful, but their limitations include functional group incompatibility, narrow scope of application, high cost and low availability of the catalysts, and unproven scalability. For this reason, a new and general catalytic approach to heteroaromatic C-Si bond construction that avoids such limitations is highly desirable. Here we report an example of cross-dehydrogenative heteroaromatic C-H functionalization catalysed by an Earth-abundant alkali metal species. We found that readily available and inexpensive potassium tert-butoxide catalyses the direct silylation of aromatic heterocycles with hydrosilanes, furnishing heteroarylsilanes in a single step. The silylation proceeds under mild conditions, in the absence of hydrogen acceptors, ligands or additives, and is scalable to greater than 100 grams under optionally solvent-free conditions. Substrate classes that are difficult to activate with precious metal catalysts are silylated in good yield and with excellent regioselectivity. The derived heteroarylsilane products readily engage in versatile transformations enabling new synthetic strategies for heteroaromatic elaboration, and are useful in their own right in pharmaceutical and materials science applications.

  7. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides

    NARCIS (Netherlands)

    Hereijgers, B.P.C.; Weckhuysen, B.M.

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with al

  8. A rare earth-based metal-organic framework for moisture removal and control in confined spaces

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-13

    A method for preparing a metal-organic framework (MOF) comprising contacting one or more of a rare earth metal ion component with one or more of a tetratopic ligand component, sufficient to form a rare earth-based MOF for controlling moisture in an environment. A method of moisture control in an environment comprising adsorbing and/or desorbing water vapor in an environment using a MOF, the MOF including one or more of a rare earth metal ion component and one or more of a tetratopic ligand component. A method of controlling moisture in an environment comprising sensing the relative humidity in the environment comprising a MOF; and adsorbing water vapor on the MOF if the relative humidity is above a first level, sufficient to control moisture in an environment. The examples relate to a MOF created from 1,2,4,5-Tetrakis(4-carboxyphenyl )benzene (BTEB) as tetratopic ligand, 2-fluorobenzoic acid and Y(NO3)3, Tb(NO3)3 and Yb(NO3)3 as rare earth metals.

  9. Dynamic polarizabilities of rare-earth-metal atoms and dispersion coefficients for their interaction with helium atoms

    NARCIS (Netherlands)

    Chu, X.; Dalgarno, A.; Groenenboom, G.C.

    2007-01-01

    The dynamic scalar and tensor polarizabilities of the rare-earth-metal atoms are calculated with time-dependent density functional theory. The frequency-dependent polarizabilities at imaginary frequencies are used to determine the isotropic and orientation-dependent van der Waals coefficients for th

  10. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides

    NARCIS (Netherlands)

    Hereijgers, B.P.C.|info:eu-repo/dai/nl/314131116; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with

  11. Distribution of Sb, As, Ge, and In between metal and silicate during accretion and core formation in the Earth

    Science.gov (United States)

    Righter, K.; Nickodem, K.; Pando, K.; Danielson, L.; Boujibar, A.; Righter, M.; Lapen, T. J.

    2017-02-01

    A large number of siderophile (iron-loving) elements are also volatile, thus offering constraints on the origin of volatile elements in differentiated bodies such as Earth, Moon, Mars and Vesta. Metal-silicate partitioning data for many of these elements is lacking, making their overall mantle concentrations in these bodies difficult to model and origin difficult to distinguish between core formation and volatile depletion. To address this gap in understanding, we have undertaken systematic studies of four volatile siderophile elements - Sb, As, Ge and In - at variable temperature and variable Si content of metal. Several series were carried out at 1 GPa, and between 1500 and 1900 °C, for both C saturated and C-free conditions. The results show that temperature causes a decrease in the metal/silicate partition coefficient for all four elements. In addition, activity coefficients for each element have been determined and show a very strong dependence on Si content of Fe alloy. Si dissolved in metal significantly decreases the metal/silicate partition coefficients, at both 1600 and 1800 °C. The combination of temperature and Si content of the metal causes reduction of the metal-silicate partition coefficient to values that are close to those required for an origin of mantle As, Sb, Ge, and In concentrations by metal-silicate equilibrium processes. Combining these new results with previous studies on As, Sb, Ge, and In, allowed derivation of predictive expressions for metal/silicate partition coefficients for these elements which can then be applied to Earth. The expressions are applied to two scenarios for continuous accretion of Earth; specifically for constant and increasing fO2 during accretion. The results indicate that mantle concentrations of As, Sb, Ge, and In can be explained by metal-silicate equilibrium during an accretion scenario. The modeling is not especially sensitive to either scenario, although all element concentrations are explained better by a

  12. Recent advances in tailoring the aggregation of heavier alkaline earth metal halides, alkoxides and aryloxides from non-aqueous solvents.

    Science.gov (United States)

    Fromm, Katharina M

    2006-11-21

    This overview on one of the subjects treated in our group deals with the synthesis and study of low-dimensional polymer and molecular solid state structures formed with alkaline earth metal ions in non-aqueous solvents. We have chosen several synthetic approaches in order to obtain such compounds. The first concept deals with the "cutting out" of structural fragments from a solid state structure of a binary compound, which will be explained with reference to BaI2. Depending on the size and concentration of oxygen donor ligands, used as chemical scissors on BaI2, three-, two-, one- and zero-dimensional derived adducts of BaI2 are obtained, comparable to a structural genealogy tree for BaI2. A second part deals with the supramolecular approach for the synthesis of low dimensional polymeric compounds based on alkaline earth metal iodides, obtained by the combination of metal ion coordination with hydrogen bonding between the cationic complexes and their anions. Certain circumstances allow rules to be established for the prediction of the dimensionality of a given compound, contributing to the fundamental problem of structure prediction in crystal engineering. A third section describes a synthetic approach for generating pure alkaline earth metal cage compounds as well as alkali and alkaline earth mixed metal clusters. A first step deals with different molecular solvated alkaline earth metal iodides which are investigated as a function of the ligand size in non-aqueous solvents. These are then reacted with some alkali metal compound in order to partially or totally eliminate alkali iodide and to form the targeted clusters. These unique structures of ligand stabilized metal halide, hydroxide and/or alkoxide and aryloxide aggregates are of interest as potential precursors for oxide materials and as catalysts. Approaches to two synthetic methods of the latter, sol-gel and (MO)CVD (metal-organic chemical vapour deposition), are investigated with some of our compounds. (D

  13. Metal loading effect on rare earth element binding to humic acid: Experimental and modelling evidence

    Science.gov (United States)

    Marsac, Rémi; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

    2010-03-01

    The effect of metal loading on the binding of rare earth elements (REE) to humic acid (HA) was studied by combining ultrafiltration and Inductively Coupled Plasma Mass Spectrometry techniques. REE-HA complexation experiments were performed at pH 3 for REE/C molar ratios ranging from ca 4 × 10 -4 to 2.7 × 10 -2. Results show that the relative amount of REE bound to HA strongly increases with decreasing REE/C. A middle-REE (MREE) downward concavity is shown by patterns at high metal loading, whereas patterns at low metal loading display a regular increase from La to Lu. Humic Ion Model VI modelling are close to the experimental data variations, provided that (i) the ΔLK 2 parameter (i.e. the Model VI parameter taken into account the presence of strong but low density binding sites) is allowed to increase regularly from La to Lu (from 1.1 to 2.1) and (ii) the published log KMA values (i.e. the REE-HA binding constants specific to Model VI) are slightly modified, in particular with respect to heavy REE. Modelling approach provided evidence that logKdREE patterns with varying REE/C likely arises because REE binding to HA occurs through two types of binding sites in different density: (i) a few strong sites that preferentially complex the heavy REE and thus control the logKdREE atterns at low REE/C; (ii) a larger amount of weaker binding sites that preferentially complex the middle-REE and thus control the logKdREE pattern at high REE/C. Hence, metal loading exerts a major effect on HA-mediated REE binding, which could explain the diversity of published conditional constants for REE binding with HA. A literature survey suggests that the few strong sites activated at low REE/C could be multidentate carboxylic sites, or perhaps N-, or P-functional groups. Finally, an examination of the literature field data proposed that the described loading effect could account for much of the variation in REE patterns observed in natural organic-rich waters (DOC > 5 mg L -1 and 4

  14. Synthesis and characterization of anhydrous rare earth metal nitrates, rare earth acetates and rare earth oxyacetates; Synthese und Charakterisierung wasserfreier Seltenerdmetall-Nitrate, -Acetate und -Oxyacetate

    Energy Technology Data Exchange (ETDEWEB)

    Heinrichs, Christina

    2013-10-29

    Anhydrous rare-earth metal (RE) nitrates, RE nitrate monohydrates and RE acetates were synthesized by thermal dehydration of RE nitrate hydrates and RE acetate hydrates in an argon flow or vacuum. RE oxyacetates were synthesized by thermal decomposition of RE acetates. Furthermore praseodymium carbonate hydroxide was synthesized by heating Pr carbonate hydrate. The compounds were analyzed by X-ray powder diffraction and, for selected examples, measurements with high-resolution synchrotron radiation were performed. Three new crystal structure types were found for RE nitrates: RE(NO{sub 3}){sub 3} with RE = La - Sm (type I) crystallize monoclinically in space group C2/c with Z = 16 (CN = 12, 11). RE(NO{sub 3}){sub 3} with RE = Y, Eu - Yb (type II) crystallize monoclinically in space group P2{sub 1}/c with Z = 4 (CN = 10) and Lu(NO{sub 3}){sub 3} (type III) monoclinically in space group I2/a with Z = 16 (CN = 8, 7). With decreasing CN (coordination number) a structural trend within the RE nitrates is observed: The RE nitrates of type I with the largest RE{sup 3+} cations build a three-dimensional network, the RE nitrates of type II form close packed layers and the preliminary structural model of Lu(NO{sub 3}){sub 3} (type III) with the smallest RE{sup 3+} cation shows layers and chains. The product of the dehydration of Sc(NO{sub 3}){sub 3} . n H{sub 2}O was indexed monoclinically in space group P2{sub 1}/c. Monohydrates RE(NO{sub 3}){sub 3} . H{sub 2}O with RE = Dy - Yb crystallize isotypically with Y(NO{sub 3}){sub 3} . H{sub 2}O in the triclinic space group P anti 1 with Z = 2 (CN = 9). Pr(CH{sub 3}CO{sub 2}){sub 3} does not crystallize in the known Pr acetate type but in the trigonal space group R anti 3 with Z = 18 (CN = 10) isotypically with the La acetate type which was only known for La(CH{sub 3}CO{sub 2}){sub 3} and Ce(CH{sub 3}CO{sub 2}){sub 3} up to now. In addition to the known Ho acetate type a new crystal structure type (Ho acetate type II) was found for

  15. Synthesis and structural diversity of trivalent rare-earth metal diisopropylamide complexes.

    Science.gov (United States)

    Spallek, Tatiana; Heß, Oliver; Meermann-Zimmermann, Melanie; Meermann, Christian; Klimpel, Michael G; Estler, Frank; Schneider, David; Scherer, Wolfgang; Tafipolsky, Maxim; Törnroos, Karl W; Maichle-Mössmer, Cäcilia; Sirsch, Peter; Anwander, Reiner

    2016-09-21

    A series of rare-earth metal diisopropylamide complexes has been obtained via salt metathesis employing LnCl3(THF)x and lithium (LDA) or sodium diisopropylamide (NDA) in n-hexane. Reactions with AM : Ln ratios ≥3 gave ate complexes (AM)Ln(NiPr2)4(THF)n (n = 1, 2; Ln = Sc, Y, La, Lu; AM = Li, Na) in good yields. For smaller rare-earth metal centres such as scandium and lutetium, a Li : Ln ratio = 2.5 accomplished ate-free tris(amido) complexes Ln(NiPr2)3(THF). The chloro-bridged dimeric derivatives [Ln(NiPr2)2(μ-Cl)(THF)]2 (Ln = Sc, Y, La, Lu) could be obtained in high yields for Li : Ln = 1.6-2. The product resulting from the Li : La = 1 : 1.6 reaction revealed a crystal structure containing two different molecules in the crystal lattice, [La(NiPr2)2(THF)(μ-Cl)]2·La(NiPr2)3(THF)2. Recrystallization of the chloro-bridged dimers led to the formation of the monomeric species Ln(NiPr2)2Cl(THF)2 (Ln = Sc, Lu) and La(NiPr2)3(THF)2. The reaction of YCl3 and LDA with Li : Y = 2 in the absence of THF gave a bimetallic ate complex LiY(NiPr2)4 with a chain-like structure. For scandium, the equimolar reactions with LDA or NDA yielded crystals of tetrametallic mono(amido) species, {[Sc(NiPr2)Cl2(THF)]2(LiCl)}2 and [Sc(NiPr2)Cl2(THF)]4, respectively. Depending on the Ln(iii) size, AM, and presence of a donor solvent, ate complexes (AM)Ln(NiPr2)4(THF)n show distinct dynamic behaviour as revealed by variable temperature NMR spectroscopy. The presence of weak LnCH(iPr) β-agostic interactions, as indicated by Ln-N-C angles <105°, is corroborated by DFT calculations and NBO analysis.

  16. Alkali-earth metal bridges formed in biofilm matrices regulate the uptake of fluoroquinolone antibiotics and protect against bacterial apoptosis.

    Science.gov (United States)

    Kang, Fuxing; Wang, Qian; Shou, Weijun; Collins, Chris D; Gao, Yanzheng

    2017-01-01

    Bacterially extracellular biofilms play a critical role in relieving toxicity of fluoroquinolone antibiotic (FQA) pollutants, yet it is unclear whether antibiotic attack may be defused by a bacterial one-two punch strategy associated with metal-reinforced detoxification efficiency. Our findings help to assign functions to specific structural features of biofilms, as they strongly imply a molecularly regulated mechanism by which freely accessed alkali-earth metals in natural waters affect the cellular uptake of FQAs at the water-biofilm interface. Specifically, formation of alkali-earth-metal (Ca(2+) or Mg(2+)) bridge between modeling ciprofloxacin and biofilms of Escherichia coli regulates the trans-biofilm transport rate of FQAs towards cells (135-nm-thick biofilm). As the addition of Ca(2+) and Mg(2+) (0-3.5 mmol/L, CIP: 1.25 μmol/L), the transport rates were reduced to 52.4% and 63.0%, respectively. Computational chemistry analysis further demonstrated a deprotonated carboxyl in the tryptophan residues of biofilms acted as a major bridge site, of which one side is a metal and the other is a metal girder jointly connected to the carboxyl and carbonyl of a FQA. The bacterial growth rate depends on the bridging energy at anchoring site, which underlines the environmental importance of metal bridge formed in biofilm matrices in bacterially antibiotic resistance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Behavior and distribution of heavy metals including rare Earth elements, thorium, and uranium in sludge from industry water treatment plant and recovery method of metals by biosurfactants application.

    Science.gov (United States)

    Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

    2012-01-01

    In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90-100% using a precipitation method with alkaline solution.

  18. Ion Migration in Organometal Trihalide Perovskite and Its Impact on Photovoltaic Efficiency and Stability.

    Science.gov (United States)

    Yuan, Yongbo; Huang, Jinsong

    2016-02-16

    Organometal trihalide perovskites (OTPs) are emerging as very promising photovoltaic materials because the power conversion efficiency (PCE) of OTP solar cells quickly rises and now rivals with that of single crystal silicon solar cells after only five-years research. Their prospects to replace silicon photovoltaics to reduce the cost of renewable clean energy are boosted by the low-temperature solution processing as well as the very low-cost raw materials and relative insensitivity to defects. The flexibility, semitransparency, and vivid colors of perovskite solar cells are attractive for niche applications such as built-in photovoltaics and portable lightweight chargers. However, the low stability of current hybrid perovskite solar cells remains a serious issue to be solved before their broad application. Among all those factors that affect the stability of perovskite solar cells, ion migration in OTPs may be intrinsic and cannot be taken away by device encapsulation. The presence of ion migration has received broad attention after the report of photocurrent hysteresis in OTP based solar cells. As suggested by much direct and indirect experimental evidence, the ion migration is speculated to be the origin or an important contributing factor for many observed unusual phenomenon in OTP materials and devices, such as current-voltage hysteresis, switchable photovoltaic effect, giant dielectric constant, diminished transistor behavior at room temperature, photoinduced phase separation, photoinduced self-poling effect, and electrical-field driven reversible conversion between lead iodide (PbI2) and methylammonium lead triiodide (MAPbI3). Undoubtedly thorough insight into the ion-migration mechanism is highly desired for the development of OTP based devices to improve intrinsic stability in the dark and under illumination. In this Account, we critically review the recent progress in understanding the fundamental science on ion migration in OTP based solar cells. We look

  19. Synthesis of rare earth metal-organic frameworks (Ln-MOFs) and their properties of adsorption desulfurization

    Institute of Scientific and Technical Information of China (English)

    刘想; 王景艳; 李庆远; 蒋赛; 张天浩; 季生福

    2014-01-01

    The rare earth metal-organic frameworks (Ln-MOFs) materials, Ln(BTC)(H2O)·(DMF), were synthesized using the rare earth metal (Ln=Sm, Eu, Tb, Y) and 1,3,5-trimesic acid (BTC) as a metal ion center and ligand, respectively. X-ray diffraction (XRD) and infrared spectroscopy (FT-IR) were employed to characterize the Ln-MOFs structural features. The property of adsorption desul-furization of Ln-MOFs materials was evaluated with thiophene/n-octane as model oil. The results showed that Ln-MOFs with rare earth metals Sm, Eu, Tb and Y had perfect crystalline and good adsorption desulfurization ability. Y(BTC)(H2O)·(DMF) material had a comparatively better activity for the adsorption desulfurization with desulfurization rate up to 80.7%and the sulfur adsorption ca-pacity was found 30.7 mgS/g(Y-MOFs). The Ln-MOFs materials had excellent reusability.

  20. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    Science.gov (United States)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  1. Corrosion Inhibition Mechanism of Rare Earth Metal on LC4 Al Alloy with Spilt Cell Technique

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new method of studying the corrosion inhibition mechanism of rare earth metal(REM) on LC4 Al alloy with the spilt cell technique was studied. The principle and experimental method of the spilt cell technique were analyzed. By measuring the change of net-electric current between the two electrodes caused by the change of the amount of oxygen in the solution and the addition of CeCl3, the influence of corrosive performance of CeCl3 on LC4 super-power aluminum alloy in the 0.1 mol*L-1 NaCl solution was investigated. Meanwhile, the conditional changes of pH values, CeCl3 solution, additire and time of performance were also studied. Finally, the features of electrode surface were revealed by using SEM and X-ray energy-dispersive spectrometry (EDS). By combining these with other electric chemical techniques, such as potential-time curve, polarization curve et al.

  2. Biodiesel production using alkali earth metal oxides catalysts synthesized by sol-gel method

    Directory of Open Access Journals (Sweden)

    Majid Mohadesi

    2014-03-01

    Full Text Available Biodiesel fuel is considered as an alternative to diesel fuel. This fuel is produced through transesterification reactions of vegetable oils or animal fat by alcohols in the presence of different catalysts. Recent studies on this process have shown that, basic heterogeneous catalysts have a higher performance than other catalysts. In this study different alkali earth metal oxides (CaO, MgO and BaO doped SiO2 were used as catalyst for the biodiesel production process. These catalysts were synthesis by using the sol-gel method. A transesterification reaction was studied after 8h by mixing corn oil, methanol (methanol to oil molar ratio of 16:1, and 6 wt. % catalyst (based on oil at 60oC and 600rpm. Catalyst loading was studied for different catalysts ranging in amounts from 40, 60 to 80%. The purity and yield of the produced biodiesel for 60% CaO/SiO2 was higher than other catalysts and at 97.3% and 82.1%, respectively.

  3. Electrodeposition of alkali and alkali-earth metals on liquid lead cathodes in molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Caravaca, C.; De Cordoba, G. [CIEMAT/DE/DFN/URAA. Avda. Complutense, 22. 28040 Madrid (Spain)

    2008-07-01

    Pyrochemical processing of spent nuclear fuel leads to the dissolution as chlorides of fission products (FPs) that have to be removed in order to recycle the salt. Precipitation technique have been tested for the removal of these FPs in the LiCl-KCl, salt selected as reference, with different results. Salt decontamination from lanthanides can be easily achieved as solid precipitates of oxychlorides or single phosphates; however, for the alkaline and alkaline-earth metals this technique is not suitable. Within the EUROPART project (VI FP of the EC), a new route that consist of the electrodeposition of these FP on a liquid lead cathode (LLC) has been considered, including the Li and K constituting the electrolyte. First results obtained with Sr and Cs are presented herein. Although according to the thermodynamic potential values, the electrodeposition order on LLC is Ba, Sr, Li, K and Cs, during our experiments it was not possible to distinguish the electrochemical signals corresponding to the individual elements. (authors)

  4. In Vivo Uptake of Rare Earth Metals by Triple-Negative Breast Cancer Cells.

    Science.gov (United States)

    Roncati, Luca; Gatti, Antonietta Morena; Barbolini, Giuseppe; Piscioli, Francesco; Pusiol, Teresa; Maiorana, Antonio

    2017-02-09

    Rare earth metals (REM) are a group of 17 chemical elements in the periodic table, namely scandium (Sc), yttrium (Y) and the lanthanides. In relation to atomic volume and geological behavior, the lanthanides are further subdivided into light, medium and heavy REM. They find many applications in the technological field; however, their impact on the human health is still conflicting and, for many aspects, unknown. During a research program carried on 113 cases of female breast cancer, immunohistochemically categorized in Her2-positive (29 cases), Her2-negative (57 cases) and triple negative (27 cases), aimed to evaluate the role of environmental particulate in carcinogenesis by elemental microanalysis, for the first time in literature we have detected a REM uptake, in detail europium (Eu), dysprosium (Dy) and praseodymium (Pr), inside the neoplastic cells belonging to a single triple negative breast cancer. Curiously, the woman affected by this form of malignancy had worked in the ceramic industry, a well-known source of REM, during her life, and she was the one and only patient of our series to be dedicated to this activity. The medical repercussions of our findings are here discussed: in fact, a REM detection in only 1 of 113 examined cases seems to exclude active roles in breast carcinogenesis and discloses new possibilities for therapeutic developments in triple negative breast cancer.

  5. Homoleptic rare-earth metal(III) tetramethylaluminates: structural chemistry, reactivity, and performance in isoprene polymerization.

    Science.gov (United States)

    Zimmermann, Melanie; Frøystein, Nils Age; Fischbach, Andreas; Sirsch, Peter; Dietrich, H Martin; Törnroos, Karl W; Herdtweck, Eberhardt; Anwander, Reiner

    2007-01-01

    The complexes [Ln(AlMe4)3] (Ln=Y, La, Ce, Pr, Nd, Sm, Ho, Lu) have been synthesized by an amide elimination route and the structures of [Lu{(micro-Me)2AlMe2}3], [Sm{(micro-Me)2AlMe2}3], [Pr{(micro-Me)2AlMe2}3], and [La{(micro-Me)2AlMe2}2{(micro-Me)3AlMe}] determined by X-ray crystallography. These structures reveal a distinct Ln3+ cation size-dependency. A comprehensive insight into the intrinsic properties and solution coordination phenomena of [Ln(AlMe4)3] complexes has been gained from extended dynamic 1H and 13C NMR spectroscopic studies, as well as 1D 89Y, 2D 1H/89Y, and 27Al NMR spectroscopic investigations. [Ce(AlMe4)3] and [Pr(AlMe4)3] have been used as alkyl precursors for the synthesis of heterobimetallic alkylated rare-earth metal complexes. Both carboxylate and siloxide ligands can be introduced by methane elimination reactions that give the heterobimetallic complexes [Ln{(O2CAriPr)2(micro-AlMe2)}2(AlMe4)(C6H14)n] and [Ln{OSi(OtBu)3}(AlMe3)(AlMe4)2], respectively. [Pr{OSi(OtBu)3}(AlMe3)(AlMe4)2] has been characterized by X-ray structure analysis. All of the cerium and praseodymium complexes are used as precatalysts in the stereospecific polymerization of isoprene (1-3 equivalents of Et2AlCl as co-catalyst) and compared to the corresponding neodymium-based initiators reported previously. The superior catalytic performance of the homoleptic complexes leads to quantitative yields of high-cis-1,4-polyisoprene (>98%) in almost all of the polymerization experiments. In the case of the binary catalyst mixtures derived from carboxylate or siloxide precatalysts quantitative formation of polyisoprene is only observed for nLn:nCl=1:2. The influence of the metal size is illustrated for the heterobimetallic lanthanum, cerium, praseodymium, neodymium, and gadolinium carboxylate complexes, and the highest activities are observed for praseodymium as a metal center in the presence of one equivalent of Et2AlCl.

  6. Difference of coordination between alkali- and alkaline-earth-metal ions to a symmetrical α,α',δ,δ'-tetramethylcucurbit[6]uril.

    Science.gov (United States)

    Chen, Wen-Jian; Yu, Da-Hai; Xiao, Xin; Zhang, Yun-Qian; Zhu, Qian-Jiang; Xue, Sai-Feng; Tao, Zhu; Wei, Gang

    2011-08-01

    To explore differences in coordination between alkali- and alkaline-earth-metal ions and cucurbit[n]urils, a water-soluble α,α',δ,δ'-tetramethylcucurbit[6]uril (TMeQ[6]) was used to synthesize a series of complexes and their supramolecular assemblies, based on the coordination of TMeQ[6] with alkali- and alkaline-earth-metal ions. The complexes and corresponding supramolecular assemblies were structurally characterized by single-crystal X-ray diffraction. Unlike cucurbituril (Q[6]), which formed the metal-Q[6] polymers based on the direct coordination of carbonyl oxygen atoms to the alkali-metal ions, TMeQ[6] formed metal-TMeQ[6] polymers based on the direct coordination of carbonyl oxygen atoms with the alkaline-earth-metal ions rather than the alkali-metal ions.

  7. Metal nitride cluster as a template to tune the electronic and magnetic properties of rare-earth metal containing endohedral fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang

    2013-10-16

    Rare-earth metal containing endohedral fullerenes have attracted much attention due to the feasibility of encaging metal atom, atoms or cluster inside of carbon cages. By switching the metal atom or cluster entrapped inside of the carbon cage the physical and chemical properties of the fullerene compounds can be tuned. The understanding of magnetic and electrochemical properties of endohedral fullerenes plays an essential role in fundamental scientific researches and potential applications in materials science. In this thesis, synthesizing novel rare-earth metal containing endohedral fullerene structures, studying the properties of these isolated endohedral fullerenes and the strategies of tuning the electronic and magnetic properties of endohedral fullerenes were introduced. The DC-arc discharging synthesis of different lanthanide metal-based (Ho, Ce and Pr) mixed metal nitride clusterfullerenes was achieved. Those rare-earth metal containing endohedral fullerenes were isolated by multi-step HPLC. The isolated samples were characterized by spectroscopic techniques included UV-vis-NIR, FTIR, Raman, LDI-TOF mass spectrometry, NMR and electrochemistry. The Ho-based mixed metal nitride clusterfullerenes Ho{sub x}M{sub 3-x}N rate at C{sub 80} (M= Sc, Lu, Y; x=1, 2) were synthesized by ''reactive gas atmosphere'' method or ''selective organic solid'' route. The isolated samples were characterized by LDI-TOF mass spectrometry, UV-vis-NIR, FTIR, Raman and NMR spectroscopy. The {sup 13}C NMR spectroscopic studies demonstrated exceptional NMR behaviors that resulted from switching the second metal inside of the mixed metal nitride cluster Ho{sub x}M{sub 3-x}N from Sc to Lu and further to Y. The LnSc{sub 2}N rate at C{sub 80} (Ln= Ce, Pr, Nd, Tb, Dy, Ho, Lu) MMNCFs were characterized by {sup 13}C and {sup 45}Sc NMR study respectively. According to Bleaney's theory and Reilley method, the separation of δ{sup PC} and δ{sup con

  8. Understanding of the formation of shallow level defects from the intrinsic defects of lead tri-halide perovskites.

    Science.gov (United States)

    Kim, Jongseob; Chung, Choong-Heui; Hong, Ki-Ha

    2016-10-05

    Organic-inorganic hybrid perovskites have unique electronic properties in which deep level defects are rarely formed. This unique defect characteristic is the source of the long carrier diffusion length. This theoretical study shows what causes this characteristic formation of shallow level defects in lead tri-halide perovskites. Comparative studies between iodides and other halides showed that deep level defect states were generated for Cl based perovskites. Longer Pb-halide bond lengths and narrower band gaps are beneficial for preventing deep level defect states. Additionally, our study shows that the formation of shallow level defects does not change even when the lattice structures of the perovskites do not reach their equilibrium structures.

  9. Stabilization effects of third element on CaCu5 type derivatives of rare-earth transition-metal intermetallics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Part of the results of the key project "Search for novel rare-earth functional materials" supported by the National Natural Science Foundation of China is reviewed. In combination with reports in literature, the effects of the third element M on the formation and stability of La2(Co, M)17, R(Fe, M)12 and R3(Fe, M)29 intermetallic compounds are discussed by considering mixing enthalpy of M with rare-earth, Fe and Co, and atomic radius, electronegativity and electronic configurations, etc. It is concluded that the mixing en thalpy and atomic radius dominate the preferential sites and the minimum amount of M required to stabilize a structure, which ultimately affect the magnetic properties of a compound prominently. This review should provide some heuristic hints for exploiting novel rare-earth transition metal functional materials and for improving their performance.

  10. The Effect of Ormosil Matrix Composition and Alkaline Earth Metal Doping on the Photochromic Response of Ormosil-Phosphotungstate Films

    OpenAIRE

    Ferreira Neto,Elias P.; Simões,Mateus B.; Noveletto,Julia C.; Yabarrena,Jean M. S. C.; Ullah,Sajjad; Ubirajara P. Rodrigues Filho

    2015-01-01

    In this study, polyoxometallate based hybrid photochromic materials were prepared by incorporating phosphotungstate anion, PW12O403−, (PW) in hybrid tetraethyl orthosilicate and (3-glycidyloxypropyl)trimethoxysilane TEOS-GPTMS derived organomodified silicates (Ormosil) matrices by sol-gel method and the resulting materials were used to prepare multilayer films by dip-coating method. The effect of alkaline earth metal cations doping and matrix composition (%GPTMS) on the photochromic res...

  11. Spin-Orbit-Coupled Correlated Metal Phase in Kondo Lattices: An Implementation with Alkaline-Earth Atoms

    Science.gov (United States)

    Isaev, L.; Schachenmayer, J.; Rey, A. M.

    2016-09-01

    We show that an interplay between quantum effects, strong on-site ferromagnetic exchange interaction, and antiferromagnetic correlations in Kondo lattices can give rise to an exotic spin-orbit coupled metallic state in regimes where classical treatments predict a trivial insulating behavior. This phenomenon can be simulated with ultracold alkaline-earth fermionic atoms subject to a laser-induced magnetic field by observing dynamics of spin-charge excitations in quench experiments.

  12. Optimization of film synthesized rare earth transition metal permanent magnet systems. Progress report, August 1, 1991--July 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Cadieu, F.J.

    1992-08-01

    Progress is reported in three areas: high coercivity Sm-Fe-Ti-V, Sm-Fe-Zr, and two element Sm-Fe Sm{sub 5}(Fe,T){sub 17} type crystalline phases; ThMn{sub 12} type pseudobinary SmFe{sub 12-x}T{sub x}(0{le}{times}{le}1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films. (DLC)

  13. Spin-Orbit-Coupled Correlated Metal Phase in Kondo Lattices: An Implementation with Alkaline-Earth Atoms.

    Science.gov (United States)

    Isaev, L; Schachenmayer, J; Rey, A M

    2016-09-23

    We show that an interplay between quantum effects, strong on-site ferromagnetic exchange interaction, and antiferromagnetic correlations in Kondo lattices can give rise to an exotic spin-orbit coupled metallic state in regimes where classical treatments predict a trivial insulating behavior. This phenomenon can be simulated with ultracold alkaline-earth fermionic atoms subject to a laser-induced magnetic field by observing dynamics of spin-charge excitations in quench experiments.

  14. China Nonferrous Metal Invested 1.3-billion in a Rare Earth Separation Project in Xinfeng,Guangdong

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>On the 9th Oct,a signing ceremony on project investment and construction was held between China Nonferrous Metal Industry’s Foreign Engineering and Construction Co.,Ltd.and the Xinfeng County Government,Guangdong.According to agreement,the company will invest RMB 1.3 billion in Xinfeng County to develop a rare earth separation project in the south,in

  15. Palladium-rare-earth metal alloys-advanced materials for hydrogen power engineering

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Hydrogen of no less than 99. 999 % (vol. fraction) purity is a principal power media of hydrogen power engineering. A single method for the preparation of high purity hydrogen consists in its separation from vapour-gas mixtures via the selective diffusion of hydrogen through a palladium membrane. The rate of hydrogen diffusion and the strength and stability during the operation in aggressive gases are important characteristics of palladium membranes. The increase in the strength, plasticity, and hydrogen-permeability of membrane alloys can be reached by alloying palladium with the formation of solid solutions.The formation of wide ranges of palladium-rare-earth metal (REM) solid solutions is an interesting feature of palladium. Earlier, we have shown that the alloying of Pd with REM substantially increases the rate of hydrogen diffusion and markedly increases the strength of palladium on retention of the adequate plasticity.In this work, we have studied alloys of the Pd-Y and Pd-Y-Me systems. It was shown that the following conditions should be satisfied to prepare high-quality alloys exhibiting high service properties: (1)the use of high-purity components (whose purity is no less than 99.95%, mass fraction), in particular,high-purity Y prepared by vacuum distillation, and (2) holding the reached purity for the final product.For this purpose, we suggested a cycle of manufacturing operations including the preparation of a vacuumtight foil of 50 (m thick as the final stage.The hydrogen-permeability of the alloys was measured at different temperatures and hydrogen pressures. The instability of operation of binary Pd-Y alloys w alloying the composition with a Ⅷ Group metal. For example, the alloy of the optimum composition Pd-8Y-Me in the annealed state exhibits the following mechanical properties: HV= 75 kg/mm2 , σu = 58 kg/mm2 , and δ= 20%. Its hydrogen-permeability (QH2) measured as a function of the temperature exceeds that of the Pd-23Ag alloy (that is widely

  16. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater.

    Science.gov (United States)

    Saqib, Najm Us; Adnan, Rohana; Shah, Irfan

    2016-08-01

    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.

  17. Calculation of Interaction Parameters from Immiscible Phase Diagram of Alkali Metal or Alkali Earth Metal-Halide System by Means of Subregular Solution Model

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this paper, the interaction parameters in the subregular solution model, λ1 and λ2, are regarded as a linear function of temperature, T. Therefore, the molar excess Gibbs energy of A-B binary system may be reexpressed as follows: The calculation of the model parameters, λ11, λ12, λ21 and λ22, was carried out numerically from the phase diagrams for 11 alkali metal-alkali halide or alkali earth metal-halide systems.In addition, artificial neural network trained by known data has been used to predict the values of these model parameters. The predicted results are in good agreement with the.calculated ones. The applicability of the subregular solution model to the alkali metal-alkali halide or alkali earth metal-halide systems were tested by comparing the available experimental composition along the boundary of miscibility gap with the calculated ones which were obtained by using genetic algorithm. The good agreement between the calculated and experimental results across the entire liquidus is valid evidence in support of the model.

  18. Microstructure and composition of rare earth-transition metal-aluminium-magnesium alloys

    Directory of Open Access Journals (Sweden)

    Lia Maria Carlotti Zarpelon

    2008-03-01

    Full Text Available The determination of the microstructure and chemical composition of La0.7-xPr xMg0.3Al 0.3Mn0.4Co0.5 Ni3.8 (0 < x < 0.7 metal hydride alloys has been carried out using scanning electron microscopy (SEM, energy dispersive X ray analysis (EDX and X ray diffraction analysis (XRD. The substitution of La with Pr changed the grain structure from equiaxial to columnar. The relative atomic ratio of rare earth to (Al, Mn, Co, Ni in the matrix phase was 1:5 (LaNi5-type structure. Magnesium was detected only in two other phases present. A grey phase revealed 11 at.% Mg and the concentration ratios of other elements indicated the composition to be close to PrMgNi4. A dark phase was very heterogeneous in composition, attributed to the as-cast state of these alloys. The phases identified by XRD analysis in the La0.7Mg0.3Al0.3Mn0.4Co 0.5Ni3.8 alloy were: La(Ni,Co5, LaAl(Ni,Co4, La2(Ni,Co7 and AlMn(Ni,Co2. Praseodymium favors the formation of a phase with a PuNi3-type structure. Cobalt substituted Ni in the structures and yielded phases of the type: Pr(Ni,Co5 and Pr(Ni,Co3.

  19. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Science.gov (United States)

    Li, Jiawei; Huo, Juntao; Law, Jiayan; Chang, Chuntao; Du, Juan; Man, Qikui; Wang, Xinmin; Li, Run-Wei

    2014-08-01

    The effects of heavy rare earth (RE) additions on the Curie temperature (TC) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune TC in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔSM) and refrigerant capacity (RC) of the alloys. The observed values of ΔSM and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd5Ge1.9Si2Fe0.1. The tunable TC and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  20. On halide derivatives of rare-earth metal(III) oxidomolybdates(VI) and -tungstates(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Schleid, Thomas; Hartenbach, Ingo [Stuttgart Univ. (Germany). Inst. for Inorganic Chemistry

    2016-11-01

    Halide derivatives of rare-earth metal(III) oxidomolybdates(VI) have been investigated comprehensively over the last decade comprising the halogens fluorine, chlorine, and bromine. Iodide-containing compounds are so far unknown. The simple composition REXMoO{sub 4} (RE=rare-earth element, X=halogen) is realized for X=F almost throughout the complete lanthanide series as well as for yttrium. While ytterbium and lutetium do not form any fluoride derivative, for lanthanum, only a fluoride-deprived compound with the formula La{sub 3}FMo{sub 4}O{sub 16} is realized. Moreover, molybdenum-rich compounds with the formula REXMo{sub 2}O{sub 7} are also known for yttrium and the smaller lanthanoids. For X=Cl the composition REClMoO{sub 4} is known for yttrium and the whole lanthanide series, although, four different structure types were identified. Almost the same holds for X=Br, however, only two different structure types are realized in this class of compounds. In the case of halide derivatives of rare-earth metal(III) oxidotungstates(VI) the composition REXWO{sub 4} is found for chlorides and bromides only, so far. Due to the similar size of Mo{sup 6+} and W{sup 6+} cations, the structures found for the tungstates are basically the same as for the molybdates. With the larger lanthanides, the representatives for both chloride and bromide derivates exhibit similar structural motifs as seen in the molybdates, however, the crystal structure cannot be determined reliably. In case of the smaller lanthanoids, the chloride derivatives are isostructural with the respective molybdates, although the existence ranges differ slightly. The same is true for rare-earth metal(III) bromide oxidotungstates(VI).

  1. A rare earth alloy as a synthetic reagent: contrasting homo metallic rare earth and hetero bimetallic outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, G.B.; Forsyth, C.M.; Junk, P.C.; Leary, S.G. [Monash Univ., School of Chemistry, Clayton (Australia)

    2006-04-15

    Reaction of LaNi{sub 5} with 2,2'-dipyridyl-amine (HNpy{sub 2}) at 170 C under vacuum gave crystals of dimeric [La(Npy{sub 2}){sub 3}]{sub 2} as a previously unknown eight-coordinate isomer (1a) (two {mu}-{eta}{sup 2}:{eta}{sup 2} and two terminal chelating (Namide,Npy) Npy{sub 2} ligands), which reverts to the known ten coordinate isomer (1b) on recrystallization from THF/PhMe, thereby establishing linkage isomerism of a [Ln(Npy{sub 2}){sub 3}]{sub 2} complex for the first time. Reaction of 8-hydroxyquinoline (HOQ) with excess LaNi{sub 5} alloy at 190 C resulted in extraction of both metals and the formation of hetero-bimetallic [Ni{sub 2}La(OQ){sub 7}] (2). The trinuclear complex has two terminal, fac-octahedral nickel(II) sites, each bound to three chelating 8-quinolinolate anions which bridge through the oxygen atoms to the lanthanum(III) centre. The eight-coordinate lanthanum environment is completed by a chelating OQ ligand. (authors)

  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. Synthesis by coprecipitation technique and spectroscopic properties of some phosphates. [Yttrium or rare earth and potassium and alkaline earth metal phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Arbus, A.; Duranceau, C.; Zambon, D.; Cousseins, J.C. (Clermont-Ferrand-2 Univ., 63 - Aubiere (FR))

    1991-01-01

    The coprecipitation process has been used for the synthesis of some KBLn(PO{sub 4}){sub 2} compounds where B is an alkaline earth metal and Ln a lanthanide or yttrium. After the gel stage, an amorphous powder is obtained by drying, the thermal evolution of which is studied by X-ray diffraction. The temperature of calcination for the different powders is included in the 500-700{sup 0}C range, lower than that of the classical solid state synthesis, 800-1000{sup 0}C. The final phosphates crystallize with monoclinic or tetragonal symmetry. The spectroscopic properties of some Eu{sup 3+}-doped compounds prepared by coprecipitation technique are reported.

  4. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    Directory of Open Access Journals (Sweden)

    Martínez, S.

    1992-09-01

    Full Text Available Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide, employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium allowed us to determine the Lambert-Beer law slopes for each compound. These values are differents (bearing in mind experimental random errors, so we have could to affirm the nonexistence of solid solution between the nitrate and the alkaline halide médium. The L-B law obtained by us can be used for the Identification differentiation and quantitative analysis of these nitrates in solid phase, even if they are present in a very low concentration.

    Se ha realizado la asignación de los espectros infrarrojo (IR de los nitratos alcalinos, sódico y potásico, y de los alcalinotérreos, magnésico y cálcico, en estado sólido. Se ha visto la influencia del medio dispersante (haluro alcalino, utilizado en la preparación de la muestra sólida. El estudio cuantitativo de la absorbencia de la banda a 1.387 cm-1 (presente en los espectros IR de los cuatro nitratos en medio KBr permite determinar las pendientes de la Ley de Lambert-Beer Se comprueba que dichas pendientes son diferentes lo que conduce a poder afirmar que no se produce disolución sólida entre el KBr y el nitrato alcalino o alcalinotérreo. La determinación de la ley de Lambert-Beer permite la identificación y el análisis cualitativo y cuantitativo por espectroscopia IR de estos nitratos cuando están presentes en bajas concentraciones en muestras sólidas.

  5. Hydrothermal synthesis of mixed rare earth-alkali metal or ammonium fluorides

    Institute of Scientific and Technical Information of China (English)

    由芳田; 黄世华; 时秋峰

    2010-01-01

    The recent results on hydrothermal synthesis of mixed rare earth-alkali or ammonium fluorides were presented. The initial ratios of the starting materials, pH value and reaction temperature were the critical factors for obtaining the single-phase product. Four main types of complex rare earth fluorides, AREF4, A2REF5, ARE2F7 and ARE3F10 (A=Na+, K+, Rb+, NH4+), appeared in the primary hydrothermal reactions. The correlation between cation sizes and the formation of mixed rare earth fluorides under mild hydro...

  6. Effect of Rare Earths-Treated Glass Fiber on Impact Wear-Resistance of Metal-Plastic Multilayer Composites

    Institute of Scientific and Technical Information of China (English)

    程先华; 薛玉君; 谢超英

    2002-01-01

    The friction and wear properties under impact load and dry friction conditions of metal-plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear-resistance.

  7. Lunar oxygen and metal for use in near-Earth space: Magma electrolysis

    Science.gov (United States)

    Colson, Russell O.; Haskin, Larry A.

    1990-01-01

    Because it is energetically easier to get material from the Moon to Earth orbit than from the Earth itself, the Moon is a potentially valuable source of materials for use in space. The unique conditions on the Moon, such as vacuum, absence of many reagents common on the Earth, and the presence of very nontraditional ores suggest that a unique and nontraditional process for extracting materials from the ores may prove the most practical. With this in mind, an investigation of unfluxed silicate electrolysis as a method for extracting oxygen, iron, and silicon from lunar regolith was initiated and is discussed. The advantages of the process include simplicity of concept, absence of need to supply reagents from Earth, and low power and mass requirements for the processing plant. Disadvantages include the need for uninterrupted high temperature and the highly corrosive nature of the high-temperature silicate melts which has made identifying suitable electrode and container materials difficult.

  8. Partial Oxidation of Butane to Syngas over Nickel SupportedCatalysts Modified by Alkali Metal Oxide and Rare-Earth Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The partial oxidation of butane (POB) to syngas over nickel supported catalysts was first investigated with a flow-reactor, TG and UVRRS. The NiO/g-Al2O3 is the most suitable for the POB among NiO/g-Al2O3, NiO/MgO and NiO/SiO2. And the reaction performance of the NiO/g-Al2O3 shows little difference from those of the nickel supported catalysts modified by alkali metal oxide and rare-earth metal oxide. However, modification with Li2O and La2O3 can suppress carbon-deposition of the NiO/g-Al2O3, which contains graphite-like species during the POB reaction.

  9. Catalysis by alkali and alkaline-earth metal ions in nucleophilic attack of methoxide ion on crown ethers bearing an intra-annular acetoxy group

    NARCIS (Netherlands)

    Cacciapaglia, Roberta; Lucente, Silvia; Mandolini, Luigi; Doorn, van Arie R.; Reinhoudt, David N.; Verboom, Willem

    1989-01-01

    Rates of reaction of methoxide ion with crown ethers bearing an intra-annular acetoxy group are markedly enhanced by alkali and alkaline-earth metal bromides as a result of much stronger interactions of the metal ions with transition states than with reactants. Rates of reactions of methoxide ion w

  10. Hyporheic Microbial Biofilms as Indicators of Heavy and Rare Earth Metals in the Clark Fork Basin, Montana

    Science.gov (United States)

    Barnhart, E. P.; Hornberger, M.; Hwang, C.; Dror, I.; Bouskill, N.; Short, T.; Cain, D.; Fields, M. W.

    2016-12-01

    The ability to effectively monitor the impact of hard rock mining activities on rivers and streams is a growing concern given the large number of active and abandoned mines in the western United States. One such example, the Clark Fork Basin (CFB), western Montana, was extensively mined for copper in the early 20th century: it is now one of largest U.S. EPA superfund sites. Microbial biofilms are at the base of the lotic food chain and may provide a useful biomonitoring tool for the assessment of metal toxicity due to their environmental ubiquity, rapidity of response to environmental perturbation, and importance in determining metal mobility. Hyporheic microbial biofilms from the CFB were sampled in 2014, concurrent with the USGS National Research Programs (NRP) long-term site monitoring of metals in bed sediment and aquatic benthic insects. Integration of the DNA sequencing results from the hyporheic biofilms with the sediment and insect metal concentrations correlated several bacterial phyla with metal contamination. For example, the genus Lysobacter was strongly associated with copper (Cu) bioaccumulation in the aquatic insect Hydropsyche. These results support previous studies identifying Lysobacter as a bacterial genus that is resistant to Cu ions. Our analysis is the first to indicate that specific microorganisms can act as biomarkers of Cu contamination in rivers. Moreover, our work demonstrates that changes at the microbial community level in the hyporheic zone can be coupled to observed perturbations across higher trophic levels. In 2015, extensive remediation occurred at several of the sites sampled in 2014, providing an excellent opportunity to revisit the sites and examine the temporal variability of identified biomarkers and the short-term effectiveness of remediation. In addition, samples were analyzed for rare earth metals, of which little is known, and could provide additional insight into other metals that change the microbial community structure.

  11. Cationic methyl complexes of the rare-earth metals: an experimental and computational study on synthesis, structure, and reactivity.

    Science.gov (United States)

    Kramer, Mathias U; Robert, Dominique; Arndt, Stefan; Zeimentz, Peter M; Spaniol, Thomas P; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Okuda, Jun

    2008-10-20

    Synthesis, structure, and reactivity of two families of rare-earth metal complexes containing discrete methyl cations [LnMe(2-x)(thf)n]((1+x)+) (x = 0, 1; thf = tetrahydrofuran) have been studied. As a synthetic equivalent for the elusive trimethyl complex [LnMe3], lithium methylates of the approximate composition [Li3LnMe6(thf)n] were prepared by treating rare-earth metal trichlorides [LnCl3(thf)n] with 6 equiv of methyllithium in diethyl ether. Heteronuclear complexes of the formula [Li3Ln2Me9L(n)] (Ln = Sc, Y, Tb; L = Et2O, thf) were isolated by crystallization from diethyl ether. Single crystal X-ray diffraction studies revealed a heterometallic aggregate of composition [Li3Ln2Me9(thf)n(Et2O)m] with a [LiLn2Me9](2-) core (Ln = Sc, Y, Tb). When tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = Y, Lu) was reacted with less than 1 equiv of [NR3H][BPh4], the dimethyl cations [LnMe2(thf)n][BPh4] were obtained. The coordination number as well as cis/trans isomer preference was studied by crystallographic and computational methods. Dicationic methyl complexes of the rare-earth metals of the formula [LnMe(thf)n][BAr4]2 (Ln = Sc, Y, La-Nd, Sm, Gd-Lu; Ar = Ph, C6H4F-4) were synthesized, by protonolysis of either the ate complex [Li3LnMe6(thf)n] (Ln = Sc, Y, Gd-Lu) or the tris(tetramethylaluminate) [Ln(AlMe4)3] (Ln = La-Nd, Sm, Dy, Gd) with ammonium borates [NR3H][BAr4] in thf. The number of coordinated thf ligands varied from n = 5 (Ln = Sc, Tm) to n = 6 (Ln = La, Y, Sm, Dy, Ho). The configuration of representative examples was determined by X-ray diffraction studies and confirmed by density-functional theory calculations. The highly polarized bonding between the methyl group and the rare-earth metal center results in the reactivity pattern dominated by the carbanionic character and the pronounced Lewis acidity: The dicationic methyl complex [YMe(thf)6](2+) inserted benzophenone as an electrophile to give the alkoxy complex [Y(OCMePh2)(thf)5](2+). Nucleophilic addition of

  12. Syntheses and Structures of Alkali Metal Rare Earth Polyphosphates CsLn(PO3)4 (Ln = La, Ce)

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; CHENG Wen-Dan; ZHANG Hao; WU Dong-Sheng; ZHAO Dan

    2008-01-01

    Alkali metal-rare earth polyphosphates, CsLn(PO3)4 (Ln = La, Ce), were synthesized by the high temperature solution reaction and studied by single-crystal X-ray diffraction technique. They crystallize in the monoclinic space group P21 (Z = 2) and feature infinite PO4 spiral chains linked with neighboring CsO10 and LnO8 polyhedra. In addition, theoretically calculated energy band structure and density of states (DOS) by the density functional theory(DFT) predict that the solid-state compound CsLa(PO3)4 possesses insulative character.

  13. Dihydrogen addition in a dinuclear rare-earth metal hydride complex supported by a metalated TREN ligand.

    Science.gov (United States)

    Venugopal, Ajay; Fegler, Waldemar; Spaniol, Thomas P; Maron, Laurent; Okuda, Jun

    2011-11-09

    The dinuclear lutetium dihydride dication supported by metalated tripodal ligands undergoes facile hydrogenolysis with H(2) to form a trihydride dication. Molecular orbital analysis shows that the LUMO is a bonding Lu···Lu orbital that is poised to activate dihydrogen.

  14. I. New Techniques for the Synthesis of Metals and Alloys. II. The Properties of Rare Earth Metals and Alloys

    Science.gov (United States)

    1974-11-01

    Evaporation Apparatus Gas Scattering Evaporation High Rate Physical Vapor Deposition Process Hafnium Carbide *** 20. ABSTRACT (Conttnu» on r...2,500 Aluminium oxide 2 100 Tungsten carbide 1,700 Quartz 820 Metals < 800 34 ^^M ■ ’ ■ The microstructure of the deposit shows a fine

  15. Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium—High Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    杨庆祥; 赵研辉; 等

    2002-01-01

    The modifying effect of rare earth(RE)oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics,The thermodynamic analsys for inclusion formation shows that RE oxide can be reduced to RE element by carbon,then the RE element can react with oxygen and sulfur to form the RE oxide,RE sulfide and RE oxide-sulfide in hardfacing molten pool.The deoxidization and the desulphurization can be carried otu and the liquid metal can be purified.In addition,RE oxide can also react with sulfur to form RE oxide-sulfide dirdctly.Therefore,the harmful effect of sulfur can be decreased.

  16. Siderophile elements in the upper mantle of the Earth: New clues from metal-silicate partition coefficients

    Science.gov (United States)

    Holzheid, A.; Borisov, A.; Palme, H.

    1993-01-01

    New, precise data on the solubilities of Ni, Co, and Mo in silicate melts at 1400 C and fO2 from IW to IW-2 are presented. The results suggest NiO, CoO as stable species in the melt. No evidence for metallic Ni or Co was found. Equilibrium was ensured by reversals with initially high Ni and Co in the glass. Mo appears to change oxidation state at IW-1, from MoO3 to MoO2. Metal-silicate partition coefficients calculated from these data and recent data on Pd indicate similar partition coefficients for Pd and Mo at the conditions of core formation. This unexpected result constrains models of core formation in the Earth.

  17. Rare-earth neutral metal injection into an electron beam ion trap plasma

    Energy Technology Data Exchange (ETDEWEB)

    Magee, E. W., E-mail: magee1@llnl.gov; Beiersdorfer, P.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, 96049 Bamberg (Germany)

    2014-11-15

    We have designed and implemented a neutral metal vapor injector on the SuperEBIT high-energy electron beam ion trap at the Lawrence Livermore National Laboratory. A horizontally directed vapor of a europium metal is created using a thermal evaporation technique. The metal vapor is then spatially collimated prior to injection into the trap. The source's form and quantity constraints are significantly reduced making plasmas out of metal with vapor pressures ≤10{sup −7} Torr at ≥1000 °C more obtainable. A long pulsed or constant feed metal vapor injection method adds new flexibility by varying the timing of injection and rate of material being introduced into the trap.

  18. Model calculation of the static magnetic susceptibility in light rare earth metallic systems

    Science.gov (United States)

    Hammoud, Y.; Parlebas, J. C.

    1991-05-01

    Using the impurity Anderson model in the large N_f approximation, where N_f is the orbital and spin degeneracy of the f level, we calculate the zero temperature static paramagnetic susceptibility of light rare earth metallic systems. The calculation is performed for large values of the Coulomb U_ff electron-electron interactions with respect of the V hybridization of f1 and f2 configurations with the conduction states (i.e. f0 configuration) : we only keep the leading terms in a development in successive powers of 1/U_ff and V. Our numerical results on the magnetic susceptibility start from a simple analytic expression and are discussed in terms of the f level position, the hybridization V, the shape and filling of the conduction band and also the finite U_ff effects. Finally we present calculated curves for the susceptibility versus V in connection with the αγ transition of cerium and utilizing the same parameters as those used previously to obtain core level LIII absorption spectra : also in the case of the susceptibility, the hybridization appears to be an important parameter to describe the phase change from γ to α cerium. Nous utilisons le modèle d'Anderson à une impureté dans l'approximation des grands N_f où N_f est la dégénérescence d'orbitale et de spin du niveau f et nous calculons alors la susceptibilité paramagnétique statique (à température nulle) dans les systèmes métalliques de terres rares légères. Nous effectuons notre calcul pour des valeurs de l'interaction de Coulomb U_ff grandes par rapport à l'hybridation V des configurations f1 et f2 avec les états de conduction (c.-à-d. la configuration f0): nous ne retenons que les termes les plus imporatnts dans un développement en puissances successives de 1/U_ff et V. Ensuite nous discutons nos résultats numériques à partir d'une forme analytique simple obtenue pour la susceptibilité magnétique en fonction de la position du niveau f, de l'hybridation V, de la forme et du

  19. Elemental partitioning and isotopic fractionation of Zn between metal and silicate and geochemical estimation of the S content of the Earth's core

    CERN Document Server

    Mahan, B; Pringle, E A; Moynier, F

    2016-01-01

    Zinc metal-silicate fractionation provides experimental access to the conditions of core formation and Zn has been used to estimate the S contents of the Earth's core and of the bulk Earth, assuming that they share similar volatility and that Zn was not partitioned into the Earth's core. We have conducted a suite of partitioning experiments to characterize Zn metal-silicate elemental and isotopic fractionation as a function of time, temperature, and composition. Experiments were conducted at temperatures from 1473-2273K, with run durations from 5-240 minutes for four starting materials. Chemical and isotopic equilibrium is achieved within 10 minutes. Zinc metal-silicate isotopic fractionation displays no resolvable dependence on temperature, composition, or oxygen fugacity. Thus, the Zn isotopic composition of silicate phases can be used as a proxy for bulk telluric bodies. Results from this study and literature data were used to parameterize Zn metal-silicate partitioning as a function of temperature, pressu...

  20. Rare Power China begins reinvigorate the rare earth industry after decades of underselling the valua metals

    Institute of Scientific and Technical Information of China (English)

    HU YUE

    2011-01-01

    On May 19,the State Council released Guidelines to Promote Sustainable and Sound Development of the Rare Earth Industry,delivering a strong boost to the fragmented industry.Rare earth elements,a collection of 17 elements,are among the most soughtafter materials for modern manufacturing.Their unique magnetic and phosphorescent properties make them vital ingredients in sophisticated hi-tech devices like batteries,magnets,wind turbines,cellphones,electric cars and flat-screen televisions.However,mining and smelting the elements are difficult and costly.

  1. Review of magnetic properties and magnetocaloric effect in the intermetallic compounds of rare earth with low boiling point metals

    Science.gov (United States)

    Ling-Wei, Li

    2016-03-01

    The magnetocaloric effect (MCE) in many rare earth (RE) based intermetallic compounds has been extensively investigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s) (Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi2B2C superconductors is also presented. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374081 and 11004044), the Fundamental Research Funds for the Central Universities, China (Grant Nos. N150905001, L1509006, and N140901001), the Japan Society for the Promotion of Science Postdoctoral Fellowships for Foreign Researchers (Grant No. P10060), and the Alexander von Humboldt (AvH) Foundation (Research stipend to L. Li).

  2. Effect of Rare Earth Metals, Sr, and Ti Addition on the Microstructural Characterization of A413.1 Alloy

    Directory of Open Access Journals (Sweden)

    M. G. Mahmoud

    2017-01-01

    Full Text Available The present work was performed on A413.1 alloy containing 0.2–1.5 wt% rare earth metals (lanthanum or cerium, 0.05–0.15% Ti, and 0–0.02 wt% Sr. These elements were either added individually or combined. Thermal analysis, image analysis, and electron probe microanalysis were the main techniques employed in the present study. The results show that the use of the depression in the eutectic temperature as a function of alloy modification cannot be applied in the case when the alloy is treated with rare earth metals. Increasing the concentration of RE increases the solidification zone especially in Sr-modified alloys leading to poor feeding ability. This observation is more prominent in the case of Ce addition. Depending upon the amount of added Ti, two RE based intermetallics can be formed: (i a white phase, mainly platelet-like (approximately 2.5 μm thick, that is rich in RE, Si, Cu, and Al and (ii a second phase made up of mainly grey sludge particles (star-like branching in different directions. The grey phase is rich in Ti with some RE (almost 20% of that in the white phase with traces of Si and Cu. There is a strong interaction between RE and Sr leading to a reduction in the efficiency of Sr as a eutectic Si modifier causing particle demodification.

  3. Impurities especially titanium in the rare earth metal gadolinium-before and after solid state electrotransport

    Institute of Scientific and Technical Information of China (English)

    苗睿瑛; 张小伟; 朱琼; 张志琦; 王志强; 颜世宏; 陈德宏; 周林; 李宗安

    2014-01-01

    Gadolinium was prepared by conventional procedures of fluorination, reduction, distillation and solid state electrotransport (SSE). The electronegativities of the metals were found to have an important influence on the electrotransport process and result of the impurity element. Meanwhile, titanium particles in the distilled gadolinium as major metallic impurities were studied by high resolution transmission electron microscopy (HRTEM) before and after solid state electrotransport. The results showed that impurities especially titanium transported from anode to cathode during SSE. In the metal before SSE, there were impurities of titanium in strip shape or embedded round shape. After SSE processing, titanium particles in the metal smaller than 50 nm in the cathode, but existed 6 to 10 times bigger in the anode.

  4. Charge carrier transport properties of methyl-ammonium-lead-trihalide perovskites investigated by the time-of-flight method

    Science.gov (United States)

    Lafalce, Evan; Zhang, Chuang; Vardeny, Z. Valy; University of Utah Team

    We studied the charge transport properties of methyl-ammonium-lead-trihalide perovskites using the photocurrent transient time-of-flight method. Various morphologies that include single-crystals and thin films with different crystalline grain sizes and surface roughness were investigated. The photocurrent transients were recorded as a function of excitation wavelength, intensity, and applied electric field as well as the sample temperature. We found that surface recombination leads to a photocurrent response that is sharply peaked at the band edge. While the carrier mobility depends on the sample preparation and sample temperature, typical values are on the order of 1cm2/Vs, consistent with previous reports using similar methods. This value is high compared to other solution-processed semiconductors such as pi-conjugated polymers and quantum dots; however it is relatively low compared to inorganic semiconductors. Therefore determining the mobility limiting factors in hybrid perovskite devices is important for progress in their optoelectronic device performance. This work was funded by ONR Grant N00014-15-1-2524 at the Un. of Utah.

  5. 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.

  6. 2D and 3D alkaline earth metal carboxyphosphonate hybrids: Anti-corrosion coatings for metal surfaces

    Science.gov (United States)

    Demadis, Konstantinos D.; Papadaki, Maria; Raptis, Raphael G.; Zhao, Hong

    2008-03-01

    Reactions of Mg 2+ ( 1), Ca 2+ ( 2), Sr 2+ ( 3), or Ba 2+ ( 4) salts with hydroxyphosphonoacetic acid (HPAA) at a 1:1 ratio yield M-HPAA layered coordination polymers. The crystal structures of 3 (two phases) and 4 have been determined by single crystal X-ray crystallography. Both stereoisomers ( R and S) of HPAA are incorporated in the metal-HPAA materials. Synergistic combinations of Sr 2+ or Ba 2+ and HPAA at pH 7.3 are effective corrosion inhibitors for carbon steel, but are ineffective at pH 2.0.

  7. Effect of metal cation replacement on the electronic structure of metalorganic halide perovskites: Replacement of lead with alkaline-earth metals

    Science.gov (United States)

    Pazoki, Meysam; Jacobsson, T. Jesper; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

    2016-04-01

    Organic and inorganic lead halogen perovskites, and in particular, C H3N H3Pb I3 , have during the last years emerged as a class of highly efficient solar cell materials. Herein we introduce metalorganic halogen perovskite materials for energy-relevant applications based on alkaline-earth metals. Based on the classical notion of Goldschmidt's rules and quantum mechanical considerations, the three alkaline-earth metals, Ca, Sr, and Ba, are shown to be able to exchange lead in the perovskite structure. The three alkaline-earth perovskites, C H3N H3Ca I3,C H3N H3Sr I3 , and C H3N H3Ba I3 , as well as the reference compound, C H3N H3Pb I3 , are in this paper investigated with density functional theory (DFT) calculations, which predict these compounds to exist as stable perovskite materials, and their electronic properties are explored. A detailed analysis of the projected molecular orbital density of states and electronic band structure from DFT calculations were used for interpretation of the band-gap variations in these materials and for estimation of the effective masses of the electrons and holes. Neglecting spin-orbit effects, the band gap of MACa I3,MASr I3 , and MABa I3 were estimated to be 2.95, 3.6, and 3.3 eV, respectively, showing the relative change expected for metal cation exchange. The shifts in the conduction band (CB) edges for the alkaline-earth perovskites were quantified using scalar relativistic DFT calculations and tight-binding analysis, and were compared to the situation in the more extensively studied lead halide perovskite, C H3N H3Pb I3 , where the change in the work function of the metal is the single most important factor in tuning the CB edge and band gap. The results show that alkaline-earth-based organometallic perovskites will not work as an efficient light absorber in photovoltaic applications but instead could be applicable as charge-selective contact materials. The rather high CB edge and the wide band gap together with the large

  8. Solvent Extraction of Alkaline Earth Metals with Alkylphosphorus Acids%有机磷(膦)酸对碱土金属的萃取

    Institute of Scientific and Technical Information of China (English)

    许新; 朱屯

    2002-01-01

    Solvent extraction equilibria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester,di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent on the e/r value and hydration energy of the metal ions. The minor shift of the P-O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P-O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compounds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effect is explained by using IR spectra of the loaded organic phase.

  9. Long-range interactions between the alkali-metal atoms and alkaline earth ions

    CERN Document Server

    Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K

    2014-01-01

    Accurate knowledge of interaction potentials among the alkali atoms and alkaline earth ions is very useful in the studies of cold atom physics. Here we carry out theoretical studies of the long-range interactions among the Li, Na, K, and Rb alkali atoms with the Ca$^+$, Ba$^+$, Sr$^+$, and Ra$^+$ alkaline earth ions systematically which are largely motivated by their importance in a number of applications. These interactions are expressed as a power series in the inverse of the internuclear separation $R$. Both the dispersion and induction components of these interactions are determined accurately from the algebraic coefficients corresponding to each power combination in the series. Ultimately, these coefficients are expressed in terms of the electric multipole polarizabilities of the above mentioned systems which are calculated using the matrix elements obtained from a relativistic coupled-cluster method and core contributions to these quantities from the random phase approximation. We also compare our estim...

  10. A preorganized metalloreceptor for alkaline earth ions showing calcium versus magnesium selectivity in water: biological activity of selected metal complexes.

    Science.gov (United States)

    Amatori, Stefano; Ambrosi, Gianluca; Fanelli, Mirco; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Rossi, Patrizia

    2014-08-25

    The N,N'-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,N'-dimethylethylendiamine (Malten = L) forms the highly stable [CuH(-2)L] species in water, in which the converging maltol oxygen atoms form an electron-rich area able to host hard metal ions. When considering the alkaline earth series (AE), the [Cu(H(-2)L)] species binds all metal ions, with the exception of Mg(2+), exhibiting the relevant property to discriminate Ca(2+) versus Mg(2+) at physiological pH 7.4; the binding of the AE metal is visible to the naked eye. The stability constant values of the trinuclear [AE{Cu(H(-2)L)}2](2+) species formed reach the maximum for Ca(2+) (log K=7.7). Ca(2+) also forms a tetranuclear [Ca{Cu(H(-2)L)}]2(4+) species at a high Ca(2+) concentration. Tri- and tetranuclear calcium complexes show blue- and pink-colored crystals, respectively. [Cu(H(-2)L)] is the most active species in inducing DNA alterations. The DNA damages are compatible with its hydrolytic cleavages.

  11. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Du, Juan, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn; Man, Qikui; Wang, Xinmin; Li, Run-Wei [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Law, Jiayan [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{sub C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.

  12. Melting and metallization of silica in the cores of gas giants, ice giants and super Earths

    CERN Document Server

    Mazevet, S; Taniuchi, T; Benuzzi-Mounaix, A; Guyot, F

    2014-01-01

    The physical state and properties of silicates at conditions encountered in the cores of gas giants, ice giants and of Earth like exoplanets now discovered with masses up to several times the mass of the Earth remains mostly unknown. Here, we report on theoretical predictions of the properties of silica, SiO$_2$, up to 4 TPa and about 20,000K using first principle molecular dynamics simulations based on density functional theory. For conditions found in the Super-Earths and in ice giants, we show that silica remains a poor electrical conductor up to 10 Mbar due to an increase in the Si-O coordination with pressure. For Jupiter and Saturn cores, we find that MgSiO$_3$ silicate has not only dissociated into MgO and SiO$_2$, as shown in previous studies, but that these two phases have likely differentiated to lead to a core made of liquid SiO$_2$ and solid (Mg,Fe)O.

  13. Precious metals and rare earth elements in municipal solid waste – Sources and fate in a Swiss incineration plant

    Energy Technology Data Exchange (ETDEWEB)

    Morf, Leo S., E-mail: leo.morf@bd.zh.ch [Baudirektion Kanton Zürich, Amt für Abfall, Wasser, Energie und Luft, Zurich (Switzerland); Gloor, Rolf; Haag, Olaf [Bachema AG, Schlieren (Switzerland); Haupt, Melanie [Zentrum für nachhaltige Abfall-und Ressourcennutzung ZAR, Hinwil (Switzerland); Skutan, Stefan [Bachema AG, Schlieren (Switzerland); Lorenzo, Fabian Di; Böni, Daniel [Zentrum für nachhaltige Abfall-und Ressourcennutzung ZAR, Hinwil (Switzerland)

    2013-03-15

    Highlights: ► We carefully addressed all the very valuable comments and suggestions of the reviewers. ► We also have shortened the size of the paper and tried simplify it substantially, as requested by the reviewers (introduction 25% reduced!). ► We have decided to take the chance and have replaced the data for the “additional” elements (Cu, Cd, Zn, Pb, Sn, Cr, Ni, Fe, Al) of the earlier MFA (Morf, 2011) with data that belong to the samples of this study. ► We are convinced that with the revision the paper has significantly improved in quality and attractiveness. - Abstract: In Switzerland many kinds of waste, e.g. paper, metals, electrical and electronic equipment are separately collected and recycled to a large extent. The residual amount of municipal solid waste (MSW) has to be thermally treated before final disposal. Efforts to recover valuable metals from incineration residues have recently increased. However, the resource potential of critical elements in the waste input (sources) and their partitioning into recyclable fractions and residues (fate) is unknown. Therefore, a substance flow analysis (SFA) for 31 elements including precious metals (Au, Ag), platinum metal group elements (Pt, Rh) and rare earth elements (La, Ce, etc.) has been conducted in a solid waste incinerator (SWI) with a state-of-the-art bottom ash treatment according to the Thermo-Re® concept. The SFA allowed the determination of the element partitioning in the SWI, as well as the elemental composition of the MSW by indirect analysis. The results show that the waste-input contains substantial quantities of precious metals, such as 0.4 ± 0.2 mg/kg Au and 5.3 ± 0.7 mg/kg Ag. Many of the valuable substances, such as Au and Ag are enriched in specific outputs (e.g. non-ferrous metal fractions) and are therefore recoverable. As the precious metal content in MSW is expected to rise due to its increasing application in complex consumer products, the results of this study are

  14. Alkaline earth metal-based metal-organic framework: hydrothermal synthesis, X-ray structure and heterogeneously catalyzed Claisen-Schmidt reaction.

    Science.gov (United States)

    Saha, Debraj; Maity, Tanmoy; Koner, Subratanath

    2014-09-14

    Two alkaline earth metal-based carboxylate systems, [Mg(HL)(H2O)2]n (1) and [Ca(H2L)2]n (2) (H3L = chelidamic acid) have been hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, IR, elemental analysis, and thermo-gravimetric analysis. Compound 1 has a 2D structure incorporating two water molecules. The dehydrated species, 1a, generated from 1 by removal of the coordinated water, has been characterized by thermo-gravimetric analysis, IR, elemental analysis and variable temperature powder X-ray diffraction. Both 1 and its dehydrated species 1a catalyze the Claisen-Schmidt reaction under heterogeneous conditions, but 1a is a more effective catalyst under environmentally friendly conditions. The catalyst can readily be recovered and reused in successive cycles without detectable loss of activity. Compound 2 has a 3D structure and is thermally stable up to 540 °C, but is inactive catalytically.

  15. Comparisons between adsorption and diffusion of alkali, alkaline earth metal atoms on silicene and those on silicane: Insight from first-principles calculations

    Science.gov (United States)

    Bo, Xu; Huan-Sheng, Lu; Bo, Liu; Gang, Liu; Mu-Sheng, Wu; Chuying, Ouyang

    2016-06-01

    The adsorption and diffusion behaviors of alkali and alkaline-earth metal atoms on silicane and silicene are both investigated by using a first-principles method within the frame of density functional theory. Silicane is staler against the metal adatoms than silicene. Hydrogenation makes the adsorption energies of various metal atoms considered in our calculations on silicane significantly lower than those on silicene. Similar diffusion energy barriers of alkali metal atoms on silicane and silicene could be observed. However, the diffusion energy barriers of alkali-earth metal atoms on silicane are essentially lower than those on silicene due to the small structural distortion and weak interaction between metal atoms and silicane substrate. Combining the adsorption energy with the diffusion energy barriers, it is found that the clustering would occur when depositing metal atoms on perfect hydrogenated silicene with relative high coverage. In order to avoid forming a metal cluster, we need to remove the hydrogen atoms from the silicane substrate to achieve the defective silicane. Our results are helpful for understanding the interaction between metal atoms and silicene-based two-dimensional materials. Project supported by the Natural Science Foundation of Jiangxi Province, China (Grant Nos. 20152ACB21014, 20151BAB202006, and 20142BAB212002) and the Fund from the Jiangxi Provincial Educational Committee, China (Grant No. GJJ14254). Bo Xu is also supported by the Oversea Returned Project from the Ministry of Education, China.

  16. Elemental partitioning and isotopic fractionation of Zn between metal and silicate and geochemical estimation of the S content of the Earth's core

    Science.gov (United States)

    Mahan, Brandon; Siebert, Julien; Pringle, Emily A.; Moynier, Frédéric

    2017-01-01

    Zinc metal-silicate fractionation provides experimental access to the conditions of core formation and Zn has been used to estimate the S contents of the Earth's core and of the bulk Earth, assuming that they share similar volatility and that Zn was not partitioned into the Earth's core. Therefore, Zn provides both direct and indirect information into the origin and eventual fate of volatile and siderophile elements on Earth. However, the partitioning of Zn between metal and silicate - as well as the associated isotopic fractionation - is not well known. We have conducted a suite of partitioning experiments to characterize Zn elemental partitioning and isotopic fractionation between metal and silicate as a function of time, temperature, and composition. Experiments were conducted at 2 GPa and temperatures from 1473 K to 2273 K in a piston cylinder apparatus, with run durations from 5 to 240 min for four distinct starting materials. Chemical and isotopic equilibrium is achieved within 10 min of experimental outset. Zinc metal-silicate isotopic fractionation displays no resolvable dependence on temperature, composition, or oxygen fugacity within the data set. Therefore, the Zn isotopic composition of silicate phases can be used as a proxy for bulk telluric bodies. Partitioning results from this study and data from literature were used to robustly parameterize Zn metal-silicate partitioning as a function of temperature, pressure, and redox state. Using this parametric characterization and viable formation conditions, we have estimated a range of Zn contents in the cores of iron meteorite parent bodies (i.e. iron meteorites) of ∼0.1-150 ppm, in good agreement with natural observations. We have also calculated the first geochemical estimates for the Zn contents of the Earth's core and of the bulk Earth, at 242 ± 107 ppm and 114 ± 34 ppm (respectively), that consider the slightly siderophile behavior of Zn. These estimates of the Zn contents of the Earth's core and

  17. Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms--a new hope.

    Science.gov (United States)

    Soldán, Pavel; Zuchowski, Piotr S; Hutson, Jeremy M

    2009-01-01

    We explore the potential energy surfaces for NH molecules interacting with alkali-metal and alkaline-earth atoms using highly correlated ab initio electronic structure calculations. The surfaces for interaction with alkali-metal atoms have deep wells dominated by covalent forces. The resulting strong anisotropies will produce strongly inelastic collisions. The surfaces for interaction with alkaline-earth atoms have shallower wells that are dominated by induction and dispersion forces. For Be and Mg the anisotropy is small compared to the rotational constant of NH, so that collisions will be relatively weakly inelastic. Be and Mg are thus promising coolants for sympathetic cooling of NH to the ultracold regime.

  18. 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.

  19. Calculation of crystal-field parameters for rare-earth noble metal alloys

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, L. [MPG Research Group `Electron Systems`, Department of Physics, University of Technology, Mommsenstr. 13, D-01062, Dresden (Germany); Richter, M. [MPG Research Group `Electron Systems`, Department of Physics, University of Technology, Mommsenstr. 13, D-01062, Dresden (Germany); Eschrig, H. [MPG Research Group `Electron Systems`, Department of Physics, University of Technology, Mommsenstr. 13, D-01062, Dresden (Germany); Nitzsche, U. [MPG Research Group `Electron Systems`, Department of Physics, University of Technology, Mommsenstr. 13, D-01062, Dresden (Germany)

    1995-02-09

    The crystal-field (CF) parameters for 4f electrons of a series of rare-earth impurities in Ag and Au have been evaluated from first-principles density functional calculations of the charge distribution which are based on an optimized LCAO scheme. The localized 4f states are treated as `open core shell`. By including the self-interaction correction for the 4f states, artificial constraints on the 4f charge density employed in earlier density functional CF calculations are avoided. The calculated parameters are compared with recent neutron scattering data. ((orig.)).

  20. Calculation of crystal-field parameters for rare-earth noble metal alloys

    Science.gov (United States)

    Steinbeck, L.; Richter, M.; Eschrig, H.; Nitzsche, U.

    1995-02-01

    The crystal-field (CF) parameters for 4f electrons of a series of rare earth impurities in Ag and Au have been evaluated from first-principles density functional calculations of the charge distribution which are based on an optimized LCAO scheme. The localized 4f states are treated as 'open core shell'. By including the self-interaction correction for the 4f states, artificial constraints on the 4f charge density employed in earlier density functional CF calculations are avoided. The calculated parameters are compared with recent neutron scattering data.

  1. Rare earth metals influence on morphology of non-metallic inclusions and mechanism of GP240GH and G17CrMo5-5cast steel cracking

    Directory of Open Access Journals (Sweden)

    M. Gajewski

    2009-10-01

    Full Text Available This paper presents results of research carried out in order to specify the influence of the rare earth metals on the morphology of the occuring non-metallic inclusions as well as on the cracking mechanism of GP240GH cast carbon steel and G17CrMo5-5 (0.18%C, 1.2%Cr, 0.53%Mo high temperature cast steel. The tests have been performed on successive industrial melts adding rare earth metals to the ladle during tapping of heat melt from the furnace. It was found that ball-shaped non-metalic inclusions occuring as a result of the rare earth metals influence are heterogenic and they significantly influence the cracking mechanism of Charpy specimens and the impact strength. The morphology of the specimens fracture surface has been substantially changed as a result of the rare earth metals modification. The impact strength of the tested cast carbon steel increased from 100 J/cm2 to ca 155 J/cm2, and the high-temperature cast steel from 30 J/cm2 to ca 100 J/cm2.

  2. Low-temperature activation of methane over rare earth metals promoted Zn/HZSM-5 zeolite catalysts in the presence of ethylene

    Institute of Scientific and Technical Information of China (English)

    Hengqiang Zhang; Aiguo Kong; Yongjie Ding; Chengyong Dai; Yongkui Shan

    2011-01-01

    At low temperature of 723 K, methane can be easily activated in the presence of ethylene in the feed, and converted to higher hydrocarbons (C2-C4) and aromatics (C6-C10), through its reaction over rare metals modified Zn/HZSM-5 zeolite catalysts without undesirable carbon oxides formation.Methane can get 37.3% conversion over the above catalysts under Iow temperature, and the catalysts show a longer lifetime than usual metal supported HZSM-5 zeolite catalysts without adding any rare earth metals.The effects of methane activation over various rare earth metal promoted Zn/HZSM-5 catalysts on the products and influences of several reaction conditions such as temperature, catalyst lifetime and molar ratio of CH4/C2H4 have been discussed.

  3. Applying ellipsometry to studying the effect of two kinds of rare earth metal salts on anodizing aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    H00G Quan; QIAN Ying; LI Lingjie; ZHANG Shengtao

    2004-01-01

    The effects of rare earth metal salts (REMs), cerium(Ⅳ) salt and lanthanum (Ⅲ) salt, on the property of anodized coating of LD10 aluminum alloy are studied by corrosion tests including neutral salt spray test and copper accelerated acetic acid immersion test, polarization curves measurement, energy dispersion analyzer of X-Ray(EDAX) analysis, and in situ ellipsometry. The results show that the addition of either of the two REMs in anodizing solution hardly changes the composition of an anodized coating, while increases the thickness of barrier part and reduces the porosity of porous part, which contributed to the improvement of the corrosion resistance of the anodized coating. The results also demonstrate that the effect of cerium salt was better than that of lanthanum salt.

  4. Core and shallow-core d- to f-shell excitations in rare-earth metals

    Science.gov (United States)

    Bradley, J. A.; Moore, K. T.; van der Laan, G.; Bradley, J. P.; Gordon, R. A.

    2011-11-01

    We report on the results of probing the light lanthanide metals Ce, Pr, and Nd with inelastic x-ray and electron scattering. Aberration-corrected transmission electron microscope-based electron spectroscopy and nonresonant inelastic x-ray scattering are shown to be in a high degree of accord and here serve as complementary probes of electronic structure. The high resolution and high signal-to-noise electron technique allows for the measurement of the complex and subtle excitation spectra in the lanthanide metals, validating the applicability of the screened trivalent atomic model used for these materials. In addition, the momentum transfer dependence of the x-ray scattering is extracted and compared against atomic calculations for the most tightly bound excitonic resonances, which provides a direct test of the predicted atomic radial wave functions.

  5. Thin-layer chromatographie separation of alkaline earth metals on diethylaminoethyl cellulose.

    Science.gov (United States)

    Ishida, K

    1969-12-01

    Thin-layer Chromatographic behaviour of magnesium, calcium, strontium and barium on diethylaminoethyl cellulose has been investigated in methanol-nitric acid mixtures. R(f) values are in the order magnesium > calcium > strontium > barium. The differences in R(f) values are large enough to allow good separations of the four metal ions from each other. The best separation is obtained by the ascending technique with methanol-8M nitric acid (20:1, v v ).

  6. Effects of Alkali and Alkaline Earth Metals on N-Containing Species Release during Rice Straw Pyrolysis

    Directory of Open Access Journals (Sweden)

    Pan Gao

    2015-11-01

    Full Text Available To study the effects of inherent and external alkali and alkaline earth metallic species (AAEMs, i.e., K, Ca and Mg on the behavior of N-containing species release during rice straw (RS pyrolysis, different pretreatments were applied in numerous experiments. Results indicate that ammonia (NH3 and hydrogen cyanide (HCN are the major N-containing species and that the yields of isocyanic acid (HNCO and nitric oxide (NO are relatively low. The removal of inhert AAEMs shifts N-containing species release to a high-temperature zone according to volatile release behavior because of the increase in activation energy. The formation selectivity of NH3, HNCO, and NO increases by demineralized pretreatment, whereas HCN selectivity decreases. The formation of HNCO is mainly affected by alkaline earth metal. N-containing species release occurs in low temperatures with the addition of external AAEMs. The activation energy of samples impregnated with CaCl2 and MgCl2 sharply decreases compared to the original RS. The total yields of N-containing species are reduced significantly in the presence of KCl, CaCl2, and MgCl2 as additives. The inhibition ability of AAEMs follows the sequence MgCl2 > CaCl2 > KCl. The inhibition effect of MgCl2 can be improved by solution immersion compared with solid powder mixing. The clean biomass pyrolysis and gasification technology with low N-containing species content may be developed according to the results.

  7. Dipole Polarizability of Alkali-Metal (Na, K, Rb) - Alkaline-Earth-Metal (Ca,Sr) Polar molecules - Prospects of Alignment

    CERN Document Server

    Gopakumar, Geetha; Hada, Masahiko; Kajita, Masatoshi

    2014-01-01

    Electronic open-shell ground-state properties of selected alkali-metal (AM) - alkaline-earth-metal (AEM) polar molecules are investigated. We determine potential energy curves of the 2{\\Sigma}+ ground state at the coupled-cluster singles and doubles with partial triples (CCSD(T)) level of electron correlation. Calculated spectroscopic constants for the isotopes (23Na, 39K, 85Rb) - (40Ca, 88Sr) are compared with available theoretical and experimental results. The variation of the permanent dipole moment (PDM), average dipole polarizability, and polarizability anisotropy with internuclear distance is determined using finite-field perturbation theory at the CCSD(T) level. Owing to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u., RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for alignment and orientation in combined intense laser and external static electric fields.

  8. Ab initio properties of the ground-state polar and paramagnetic europium-alkali-metal-atom and europium-alkaline-earth-metal-atom molecules

    CERN Document Server

    Tomza, Michał

    2014-01-01

    The properties of the electronic ground state of the polar and paramagnetic europium-$S$-state-atom molecules have been investigated. Ab initio techniques have been applied to compute the potential energy curves for the europium-alkali-metal-atom, Eu$X$ ($X$=Li, Na, K, Rb, Cs), europium-alkaline-earth-metal-atom, Eu$Y$ ($Y$=Be, Mg, Ca, Sr, Ba), and europium-ytterbium, EuYb, molecules in the Born-Oppenheimer approximation for the high-spin electronic ground state. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), was employed and the scalar relativistic effects within the small-core energy-consistent pseudopotentials were included. The permanent electric dipole moments and static electric dipole polarizabilities were computed. The leading long-range coefficients describing the dispersion interaction between atoms at large internuclear distances $C_6$ are also reported. The EuK, EuRb, and EuCs molecules are examples of species poss...

  9. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS2

    Directory of Open Access Journals (Sweden)

    X. D. Li

    2015-05-01

    Full Text Available Single adsorption of different atoms on pristine two-dimensional monolayer MoS2 have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS2. Additionally, local or long-range magnetic moments of two-dimensional MoS2 sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS2 monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

  10. Synchrotron Diffraction Studies of Spontaneous Magnetostriction in Rare Earth Transition Metal Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    Thermal expansion anomalies of R2Fe14B and R2Fe17Cx (x = 0,2) (R = Y, Nd, Gd, Tb, Er) stoichiometric compounds are studied with high-energy synchrotron X-ray powder diffraction using Debye-Schemer geometry in temperature range 10K to 1000K. Large spontaneous magnetostriction up to their Curie temperatures (Tc) is observed. The a-axes show relatively larger invar effects than c-axes in the R2Fe14B compounds whereas the R2Fe17Cx show the contrary anisotropies. The iron sub-lattice is shown to dominate the spontaneous magnetostriction of the compounds. The contribution of the rare earth sublattice is roughly proportional to the spin magnetic moment of the rare earth in the R2Fe14B compounds but in R2Fe17Cx, the rare earth sub-lattice contribution appears more likely to be dominated by the local bonding. The calculation of spontaneous magnetostrain of bonds shows that the bonds associated with Fe(j2) sites in R2Fe14B and the dumbbell sites in R2Fe17Cx have larger values, which is strongly related to their largest magnetic moment and Wigner-Seitz atomic cell volume. The roles of the carbon atoms in increasing the Curie temperatures of the R2Fe17 compounds are attributed to the increased separation of Fe hexagons. The R2Fe17 and R2Fe14B phases with magnetic rare earth ions also show anisotropies of thermal expansion above c. For R2Fe17 and R2Fe14B the a a/a c > 1 whereas the anisotropy is reversed with the interstitial carbon in R2Fe17. The average bond magnetostrain is shown to be a possible predictor of the magnetic moment of Fe sites in the compounds. Both of the theoretical and

  11. Calculated crystal-field parameters for rare-earth impurities in noble metals

    Science.gov (United States)

    Steinbeck, Lutz; Richter, Manuel; Eschrig, Helmut; Nitzsche, Ulrike

    1994-06-01

    From first-principles density-functional calculations of the charge distribution the crystal-field (CF) parameters for 4f states of Er and Dy impurities in Ag and Au have been evaluated. The calculations are based on an optimized linear combination of atomic orbitals scheme, where the local-density approximation (LDA) is used for the conduction-electron states, while the localized rare-earth 4f states are treated as ``open core shell.'' As the 4f localization cannot be properly described within LDA, a self-interaction correction for the 4f states is included. In this way, any artificial constraints on the 4f charge density employed in earlier first-principles CF calculations are avoided. The calculated CF parameters agree well with recent neutron scattering data.

  12. Adsorption properties of ultradispersed powders of aluminum alloys with rare-earth metals, before and after water treatment

    Science.gov (United States)

    Ryabina, A. V.; Shevchenko, V. G.; Eselevich, D. A.

    2014-10-01

    Adsorption of nitrogen on Al-3% La, Al-1.5% Sc, and Al-3% Ce powders before and after processing with water in the relative pressure range p/p s = 10˜3 to 0.999 is experimentally studied at a temperature of 78 K. It is shown that the interaction between ultradispersed powder and water depends on the properties of the original powder, including the original content and composition of the oxide-hydroxide phases in the surface layers of metal particles, and the length and conditions of storage. Results confirming that processing powders containing rare-earth metals with water at room temperature leads to the formation of new phases and affects their morphology are presented. It is shown that the nanopores formed between crystallites on the surface of the particles during oxidation with water and subsequent thermal dehydration play an important role in the properties of powders processed with water. The specific surface and the porosity of powders are calculated.

  13. Oxides Catalysts of Rare Earth and Transient Metal for Catalytic Oxidation of Benzene

    Institute of Scientific and Technical Information of China (English)

    Liang Kun; Li Rong; Chen Jianjun; Ma Jiantai

    2004-01-01

    The catalysts of CeO2 and the mixture of CeO2 and CuO were prepared, and the activities of these catalysts for completely oxidizing benzene were studied.The results show that the optimal proportion of CeO2/CuO is 6: 4.The highest temperature at which benzene was completely oxidized on these catalysts at different airspeed was measured.Compared these catalysts with the noble metal used, our catalysts had superiority in the resources and the industrial cost besides good activities.

  14. Up-conversion processes of rare earth ions in heavy metal glasses

    Institute of Scientific and Technical Information of China (English)

    L. Grobelny; W A. Pisarski; J. Pisarska; R. Lisiecki; W. Ryba-Romanowski

    2011-01-01

    Heavy metal lead germanate glasses doubly doped with Yb3+ and Ln3+ ions (Ln=Er,Tm) were investigated.Up-conversion spectra of Er3+ and Tm3+ were registered under diode-laser excitation of Yb3+.Up-conversion luminescence bands corresponded to 4S3/2→4I15/2 (green)and 4F9/2→4I15/2 (red) transitions of Er3+ as well as 1G4→3H6 (blue) and 3H4→3H6 (NIR) transitions of Tm3+,respectively.

  15. Surface shift of the occupied and unoccupied 4f levels of the rare-earth metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Johansson, Börje; Skriver, Hans Lomholt

    1995-01-01

    The surface energy shifts of the occupied and unoccupied 4f levels for the lanthanide metals have been calculated from first principles by means of a Green’s-function technique within the tight-binding linear muffin-tin orbitals method. We use the concept of complete screening to identify the occ...... played by the initial and the different final states of the core-excitation process, permitted by the fact that the so-called initial-state effect is identical upon 4f removal and 4f addition. Surface energy and work function calculations are also reported....

  16. Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Ning; LI Guangming; YAO Zhenya; ZHAO Jianfu

    2007-01-01

    Catalytic wet air oxidation(CWAO)is one of the most promising technologies for pollution abatement.Developing catalysts with high activity and stability is crucial for the application of the CWAO process.The Mn/Ce complex oxide catalyrsts for CWAO of high concentration phenol containing wastewater were prepared by coprecipitation.The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis.The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller(BET)analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry(ICP-AES).The results show that the catalysts have high catalytic activities even at a low temperature(80℃)and low oxygen partial pressure(0.5 MPa)in a batch reactor.The metallic ion leaching is comparatively low(Mn<6.577 mg/L and Ce<0.6910 mg/L,respectively)in the CWAO process.The phenol,CODCD and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst(named CSP).The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

  17. Theoretical study on the role of surface basicity and Lewis acidity on the etherification of glycerol over alkaline earth metal oxides

    NARCIS (Netherlands)

    Calatayud, M.; Ruppert, A.M.|info:eu-repo/dai/nl/314003398; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2009-01-01

    Alkaline earth metal oxides (MO) are catalytically active in the etherification of glycerol. Density Functional Theory (DFT) calculations have been used to examine the reactivity of glycerol with MO surfaces with M=Mg, Ca, Sr or Ba. More specifically, the optimum glycerol adsorption mode and the str

  18. Alkali metal – yttrium borohydrides: The link between coordination of small and large rare-earth

    Energy Technology Data Exchange (ETDEWEB)

    Sadikin, Yolanda [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Stare, Katarina [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Schouwink, Pascal [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland); Brix Ley, Morten; Jensen, Torben R. [Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Århus C (Denmark); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerjeva 5, SI-1000 Ljubljana (Slovenia); Černý, Radovan, E-mail: radovan.cerny@unige.ch [Department of Quantum Matter Physics, Laboratory of Crystallography, University of Geneva, Quai Ernest-Ansermet 24, CH-1211 Geneva (Switzerland)

    2015-05-15

    The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five new compounds and four further ones known from previous work on the homoleptic borohydrides. Crystal structures have been solved and refined from synchrotron X-ray powder diffraction, thermal stability of new compounds have been investigated and ionic conductivity measured for selected samples. Significant coordination flexibility for Y{sup 3+} is revealed, which allows the formation of both octahedral frameworks and tetrahedral complex anions with the tetrahydroborate anion BH{sub 4} both as a linker and terminal ligand. Bi- and trimetallic cubic double-perovskites c-A{sub 3}Y(BH{sub 4}){sub 6} or c-A{sub 2}LiY(BH{sub 4}){sub 6} (A=Rb, Cs) form in all the investigated systems, with the exception of the Li–K–Y system. The compounds with the stoichiometry AY(BH{sub 4}){sub 4} crystallize in all investigated systems with a great variety of structure types which find their analog amongst metal oxides. In-situ formation of a new borohydride – closo-borane is observed during decomposition of all double perovskites. - Graphical abstract: The system Li–A–Y–BH{sub 4} (A=K, Rb, Cs) is found to contain five novel compounds and four further ones previously reported. Significant coordination flexibility of Y{sup 3+} is revealed, which can be employed to form both octahedral frameworks and tetrahedral complex anions, very different structural topologies. Versatility is also manifested in three different simultaneously occurring coordination modes of borohydrides for one metal cation, as proposed by DFT optimization of the monoclinic KY(BH{sub 4}){sub 4} structural model observed by powder diffraction. - Highlights: • The system Li-A-Y-BH{sub 4} (A=K, Rb, Cs) contains nine compounds in total. • Y{sup 3+} forms octahedral frameworks and tetrahedral complex anions. • Bi- and trimetallic double-perovskites crystallize in most systems. • Various AY(BH{sub 4}){sub 4} crystallize with

  19. Observational evidence for a metal rich atmosphere on the super-Earth GJ1214b

    CERN Document Server

    Désert, Jean-Michel; Kempton, Eliza Miller-Ricci; Berta, Zachory K; Charbonneau, David; Irwin, Jonathan; Fortney, Jonathan J; Burke, Christopher J; Nutzman, Philip

    2011-01-01

    We report observations of two consecutive transits of the warm super-Earth exoplanet GJ1214b at 3.6 and 4.5 microns with the Infrared Array Camera instrument on-board the Spitzer Space Telescope. The two transit light curves allow for the determination of the transit parameters for this system. We find these paremeters to be consistent with the previously determined values and no evidence for transit timing variations. The main investigation consists of measuring the transit depths in each bandpass to constrain the planet's transmission spectrum. Fixing the system scale and impact parameters, we measure R_p/R_star=0.1176 (+0.0008/-0.0009) and 0.1163 (+0.0010/-0.0008) at 3.6 and 4.5 microns, respectively. Combining these data with the previously reported MEarth Observatory measurements in the red optical yields constraints on the GJ1214b's transmission spectrum and allows us to rule-out a cloud-free, solar composition (i.e., hydrogen-dominated) atmosphere at 4.5 sigma confidence. This independently confirms a ...

  20. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    Science.gov (United States)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  1. A geological reconnaissance of electrical and electronic waste as a source for rare earth metals.

    Science.gov (United States)

    Mueller, Sandra R; Wäger, Patrick A; Widmer, Rolf; Williams, Ian D

    2015-11-01

    The mining of material resources requires knowledge about geogenic and anthropogenic deposits, in particular on the location of the deposits with the comparatively highest concentration of raw materials. In this study, we develop a framework that allows the establishment of analogies between geological and anthropogenic processes. These analogies were applied to three selected products containing rare earth elements (REE) in order to identify the most concentrated deposits in the anthropogenic cycle. The three identified anthropogenic deposits were characterised according to criteria such as "host rock", "REE mineralisation" and "age of mineralisation", i.e. regarding their "geological" setting. The results of this characterisation demonstrated that anthropogenic deposits have both a higher concentration of REE and a longer mine life than the evaluated geogenic deposit (Mount Weld, Australia). The results were further evaluated by comparison with the geological knowledge category of the United Nations Framework Classification for Fossil Energy and Mineral Reserves and Resources 2009 (UNFC-2009) to determine the confidence level in the deposit quantities. The application of our approach to the three selected cases shows a potential for recovery of REE in anthropogenic deposits; however, further exploration of both potential and limitations is required.

  2. Visible-Light Excitated Photocatalytic Activity of Rare Earth Metal-Ion-Doped Titania

    Institute of Scientific and Technical Information of China (English)

    谢一兵; 李萍; 袁春伟

    2002-01-01

    The rare earth ion Ce4+ doped TiO2 was prepared by sol-gel method. The average particle sizes are about 10 nm for sol phase and 55 nm for polycrystalline phase. The photocatalytic activities to degrade Reactive Brilliant Red Dye X-3B were investigated. The result reveals that the spectrum response of Ce4+-TiO2 has extended to visible region from the UV region(λ<387 nm) of pure TiO2. Amorphous phase Ce4+-TiO2 sol with an electron scavenger (1.0% atom fraction Ce4+ ion doping amount) shows the capability of the photocatalytic degradation of the dye X-3B as well as the nanocrystallite Ce4+-TiO2 with an interband trap site. Despite of the difference in the morphology of Ce4+-TiO2 photocatalyst, there is no apparent difference in respect of the decoloring effects. Whereas, polycrystalline phase Ce4+-TiO2 exhibits strong photomineralization power in comparison with the amorphous phase. The photocatalytic oxidation mechanisms of the dye molecule mainly involved in the self-photo-sensitization photolysis process by the first excited singlet oxygen (1O2) and photocatalysis process by hydroxyl radicals(*OH) under visible light irradiation.

  3. Experimental investigation of the partitioning of phosphorus between metal and silicate phases - Implications for the earth, moon and eucrite parent body

    Science.gov (United States)

    Newsom, H. E.; Drake, M. J.

    1983-01-01

    An experimental study is reported of the partitioning of Phosphorus between solid metal and basaltic silicate liquid as a function of temperature and oxygen fugacity and of the implications for the earth, moon and eucrite parent body (EPB). The relationship established between the partition coefficient and the fugacity is given at 1190 C by log D(P) = -1.12 log fO2 - 15.95 and by log D(P) = -1.53 log fO2 17.73 at 1300 C. The partition coefficient D(P) was determined, and it is found to be consistent with a valence state of 5 for P in the molten silicate. Using the determined coefficient the low P/La ratios of the earth, moon, and eucrites relative to C1 chondrites can be explained. The lowering of the P/La ratio in the eucrites relative to Cl chondrite by a factor of 40 can be explained by partitioning P into 20-25 wt% sulfur-bearing metallic liquid corresponding to 5-25% of the total metal plus silicate system. The low P/La and W/La ratios in the moon may be explained by the partitioning of P and W into metal during formation of a small core by separation of liquid metal from silicate at low degrees of partial melting of the silicates. These observations are consistent with independent formation of the moon and the earth.

  4. Mechanism of interaction relation between the rare-earth element Ce and impurity elements Pb and Bi in Ag-based filler metal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.

  5. Environmentally Friendly Economical Sequestration of Rare Earth Metals from Geothermal Waters

    Energy Technology Data Exchange (ETDEWEB)

    Stull, Dean P. [Tusaar Corp., Lafayette, CO (United States)

    2016-05-26

    The purpose of this work was to complete a proof of concept study to apply and validate a novel method developed by Tusaar for the capture and recovery of rare earth elements (known as REEs) and other critical and valuable elements from geothermal waters produced from deep within the earth. Geothermal water provides heat for power production at many geothermal power plants in the western United States. The target elements, the REEs, are vital to modern day electronics, batteries, motors, automobiles and many other consumer favorites and necessities. Currently there are no domestic sources of REEs while domestic and international demand for the products they are used in continues to rise. Many of the REEs are considered “strategically” important. A secure supply of REEs in the USA would benefit consumers and the country at large. A new method to recover these REEs from geothermal waters used at existing geothermal power plants around the country is a high priority and would benefit consumers and the USA. The result of this project was the successful development and demonstration of an integrated process for removal and recovery of the REEs from synthetic geothermal brines on a small laboratory scale. The work included preparation of model geothermal brines to test, selection of the most effective proprietary sorbent media to capture the REEs and testing of the media under a variety of potential operating conditions. Geothermal brines are generally very high in salt content and contain a wide range of elements and anions associated with the rock layers from which they are produced. Processing the geothermal water is difficult because it is corrosive and the dissolved minerals in the water precipitate easily once the temperature and pressure change. No commercial technologies have been shown to be effective or robust enough under these geothermal brine conditions to be commercially viable for removal of REEs. Technologies including ion exchange, traditional

  6. Toxicity evaluation of high-fluorescent rare-earth metal nanoparticles for bioimaging applications.

    Science.gov (United States)

    Hernandez-Adame, Luis; Cortez-Espinosa, Nancy; Portales-Pérez, Diana P; Castillo, Claudia; Zhao, Wayne; Juarez, Zaida N; Hernandez, Luis R; Bach, Horacio; Palestino, Gabriela

    2017-04-01

    Research on nanometer-sized luminescent semiconductors and their biological applications in detectors and contrasting agents is an emergent field in nanotechnology. When new nanosize technologies are developed for human health applications, their interaction with biological systems should be studied in depth. Rare-earth elements are used in medical and industrial applications, but their toxic effects are not known. In this work, the biological interaction between terbium-doped gadolinium oxysulfide nanoparticles (GOSNPs) with human peripheral blood mononuclear cells (PBMC), human-derived macrophages (THP-1), and human cervical carcinoma cell (HeLa) were evaluated. The GOSNPs were synthetized using a hydrothermal method to obtain monodisperse nanoparticles with an average size of 91 ± 9 nm. Characterization techniques showed the hexagonal phase of the Gd2 O2 S:Tb(3+) free of impurities, and a strong green emission at λemi  = 544 nm produced by Tb(3+) was observed. Toxic effects of GOSNPs were evaluated using cell viability, apoptosis, cell-cycle progression, and immunological response techniques. In addition, an Artemia model was used to assess the toxicity in vivo. Results indicated cell apoptosis in both types of cells with less sensitivity for PBMC cells compared to HeLa cells. In addition, no toxic effects were observed in the in vivo model of Artemia. Moreover, GOSNPs significantly reduced the activation and cell-cycle progression of PBMC and HeLa cells, respectively. Interestingly, an increase in proinflammatory cytokines was not observed. Our data suggest that fluorescence applications of GOSNPs for biolabeling are not toxic in primary immune cells and they may have an immunomodulatory effect. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 605-615, 2017. © 2015 Wiley Periodicals, Inc.

  7. Highly Active Rare-Earth-Metal La-Doped Photocatalysts: Fabrication, Characterization, and Their Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    S. Anandan

    2012-01-01

    Full Text Available Efficient La-doped TiO2 photocatalysts were prepared by sol-gel method and extensively characterized by various sophisticated techniques. The photocatalytic activity of La-doped TiO2 was evaluated for the degradation of monocrotophos (MCPs in aqueous solution. It showed higher rate of degradation than pure TiO2 for the light of wavelength of 254 nm and 365 nm. The rate constant of TiO2 increases with increasing La loading and exhibits maximum rate for 1% La loading. The photocatalytic activities of La-doped TiO2 are compared with La-doped ZnO; the reaction rate of the former is ~1.8 and 1.1 orders higher than the latter for the lights of wavelength 254 nm and 365 nm, respectively. The relative photonic efficiency of La-doped TiO2 is relatively higher than La-doped ZnO and commercial photocatalysts. Overall, La-doped TiO2 is the most active photocatalyst and shows high relative photonic efficiencies and high photocatalytic activity for the degradation of MCP. The enhanced photocatalytic activity of La-doped TiO2 is mainly due to the electron trapping by lanthanum metal ions, small particle size, large surface area, and high surface roughness of the photocatalysts.

  8. Role of vacancies, light elements and rare-earth metals doping in CeO2.

    Science.gov (United States)

    Shi, H; Hussain, T; Ahuja, R; Kang, T W; Luo, W

    2016-08-24

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties.

  9. Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol

    Science.gov (United States)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2012-11-01

    A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  10. Role of vacancies, light elements and rare-earth metals doping in CeO2

    Science.gov (United States)

    Shi, H.; Hussain, T.; Ahuja, R.; Kang, T. W.; Luo, W.

    2016-01-01

    The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties. PMID:27554285

  11. FTIR AND SOME PHYSICAL PROPERTIES OF ALKALINE EARTH BORATE GLASSES CONTAINING HEAVY METAL OXIDES

    Directory of Open Access Journals (Sweden)

    RAMADEVUDU.G

    2011-09-01

    Full Text Available The FTIR spectra of heavy metal oxide doped borate glasses with the general formula RO-MO-B2O3 (RO= MgO, CaO, SrO and BaO, MO=ZnO, TeO2, PbO and Bi2O3 were studied in the spectral range 400-4400cm-1 toobtain information about the influence of the glass composition on the spectra. The FTIR studies revealed that MO acted differently in RO-B2O3 glass matrix and produced small variations in the glass structure. RO oxides also affected the glass structure slightly due to mixed oxide effect. However the structural groupings present ineach series of glasses are not much affected by the composition. The effect of composition on some physical properties like density, molar volume was also carried out. The increase in the values of physical parameters such as density and glass transition temperature is attributed to conversion of [BO3]3- triangular units into BO4-tetrahedral units.

  12. Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland

    Directory of Open Access Journals (Sweden)

    Jean-Michel Jaquet

    2013-10-01

    Full Text Available In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland, suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll a (Chl a concentration (2 mg m–3. Examination by scanning electron microscopy revealed the presence of numerous dark and gelatinous patches occluding the pores of the membranes, containing high numbers of picoplanktonic cells and, in places, clusters of high-reflectance smooth microspheres (1-2 μm in diameter. Their chemical composition, determined by semi-quantitative, energy-dispersive X ray spectroscopy (EDS showed magnesium (Mg, calcium (Ca, strontium (Sr and barium (Ba (alkaline earth metals to be the dominant cations. Among the anions, phosphorus (P and carbon (C were present, but only the latter is considered here (as carbonate. The microspheres were subdivided into four types represented in a Ca-Sr-Ba ternary space. All types are confined within a domain bound by Ca>45, Sr<10 and Ba<50 (in mole %. Type I, the most frequent, displays a broad variability in Ba/Ca, even within a given cluster. Types II and III are devoid of Ba, but may incorporate P. Type IV contains only Ca. The Type I composition resembles that of benstonite, a Group IIA carbonate that was recently found as intracellular granules in a cyanobacterium from alkaline lake Alchichica (Mexico.Lake Geneva microspheres are solid, featureless and embedded in a mucilage-looking substance in the vicinity of, but seemingly not inside, picoplanktonic cells morphologically similar to Chlorella and Synechococcus. In summer 2012, the macroscopic physico-chemical conditions in lake Geneva epilimnion were such as to allow precipitation of Ca but not of Sr and Ba carbonates. Favourable conditions did exist, though, in the micro-environment provided by the combination of active picoplankton and a mucilaginous envelope. Further studies are ongoing to investigate the

  13. Rare-earth metal hydrides supported by silicon-bridged boratabenzene fluorenyl ligands: synthesis, structure and reactivity.

    Science.gov (United States)

    Wang, Chunhong; Xiang, Li; Leng, Xuebing; Chen, Yaofeng

    2017-01-24

    The reactions of rare-earth metal benzyl complexes supported by silicon-bridged boratabenzene fluorenyl ligands with PhSiH3 in toluene gave the corresponding dinuclear hydrides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-H)(THF)]2 (3-Ln; Ln = La, Nd, Gd), wherein the rare-earth metal ions are linked by both silicon-bridged boratabenzene fluorenyl ligands and hydrido ligands. The reactivity of these hydrides toward unsaturated substrates was studied. Among these, alkynides [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln(μ-CCPh)]2 (4-Ln; Ln = La, Nd) were obtained via the σ-bond metathesis reaction, when 3-Ln (Ln = La, Nd) was treated with phenylacetylene. While reacting with 3-hexyne, the mono-addition product [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}Ln]2(μ-H)[μ-C(Et)[double bond, length as m-dash]C(H)Et] (5-Ln; Ln = La, Nd) was formed. Further investigations on the reactivity of 3-La displayed that benzonitrile and tert-butyl isonitrile readily inserted into the La-H bonds, affording an azomethine complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ-N[double bond, length as m-dash]C(H)Ph}]2 (6-La) and an N-tert-butylformimidoyl complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La{μ,η(2)-C(H)[double bond, length as m-dash]N(t)Bu}]2 (7-La), respectively. The reaction with N,N'-diisopropylcarbodiimide at room temperature or at 75 °C gave a dimeric complex [{μ-[Me2Si(C13H8)(C5H4BNEt2)]}La]2(μ-H)[μ-N((i)Pr)CHN((i)Pr)] (8-La) or a monomeric complex [Me2Si(C13H8)(C5H4BNEt2)]La[N((i)Pr)CHN((i)Pr)] (9-La), respectively.

  14. Graphene oxide-rare earth metal-organic framework composites for the selective isolation of hemoglobin.

    Science.gov (United States)

    Liu, Jia-Wei; Zhang, Yue; Chen, Xu-Wei; Wang, Jian-Hua

    2014-07-09

    Graphene oxide-La(BTC)(H2O)6 (H3BTC=1,3,5-benzenetricarboxylic acid) metal organic framework composites (LaMOF-GOn, n = 1-6, corresponding to the percentage of GO at 1, 2, 3, 4, 5, and 10%) are prepared through a simple and large-scale method at room temperature. The obtained composites are characterized by ATR-FTIR spectra, SEM, XRD, TGA, and N2 adsorption-desorption isotherm. The presence of GO significantly changes the morphologies of the composites from spindly rectangular rods to irregular thick blocks and increases their surface area from 14.8 cm(2) g(-1) (LaMOFs) to 26.6 cm(2) g(-1) (LaMOF-GO3), whereas at the same time, the crystalline structure of La(BTC)(H2O)6 is maintained. As a novel solid-phase adsorbent the LaMOF-GO composite exhibits outstanding adsorption properties for proteins. The strong hydrophobic interaction, especially π-π interaction between protein and the composite, is the main driving force for protein adsorption. In particular, highly selective isolation of hemoglobin (Hb) is achieved by using LaMOF-GO3 composite as sorbent in 4 mM B-R buffer containing 0.05 mol L(-1) NaCl at pH 8. The retained Hb could be effectively recovered with a 1 mM B-R buffer at pH 10, giving rise to a recovery of 63%. The practical applicability of the LaMOF-GO3 composite is demonstrated by the selective adsorption of Hb from human whole blood, and SDS-PAGE assays indicate that Hb could be selectively isolated with high purity from biological samples of complex matrixes.

  15. Empirical links between trace metal cycling and marine microbial ecology during a large perturbation to Earth's carbon cycle

    Science.gov (United States)

    Owens, Jeremy D.; Reinhard, Christopher T.; Rohrssen, Megan; Love, Gordon D.; Lyons, Timothy W.

    2016-09-01

    Understanding the global redox state of the oceans and its cause-and-effect relationship with periods of widespread organic-carbon deposition is vital to interpretations of Earth's climatic and biotic feedbacks during periods of expanded oceanic oxygen deficiency. Here, we present a compilation of new and published data from an organic-rich locality within the proto-North Atlantic Ocean during the Cenomanian-Turonian boundary event that shows a dramatic drawdown of redox-sensitive trace elements. Iron geochemistry independently suggests euxinic deposition (i.e., anoxic and sulfidic bottom waters) for the entire section, thus confirming its potential as an archive of global marine metal inventories. In particular, depleted molybdenum (Mo) and vanadium (V) concentrations effectively record the global expansion of euxinic and oxygen-deficient but non-sulfidic waters, respectively. The V drawdown precedes the OAE, fingerprinting an expansion of oxygen deficiency prior to an expansion of euxinia. Molybdenum drawdown, in contrast, is delayed with respect to V and coincides with the onset of OAE2. Parallel lipid biomarker analyses provide evidence for significant and progressive reorganization of marine microbial ecology during the OAE in this region of the proto-North Atlantic, with the smallest relative eukaryotic contributions to total primary production occurring during metal-depleted intervals. This relationship may be related to decreasing supplies of enzymatically important trace elements. Similarly, box modeling suggests that oceanic drawdown of Mo may have approached levels capable of affecting marine nitrogen fixation. Predictions of possible nitrogen stress on eukaryotic production, locally and globally, are consistent with the low observed levels of Mo and a rise in 2-methylhopane index values during the peak of the OAE. At the same time, the environmental challenge presented by low dissolved oxygen and euxinia coincides with increased turnover rates of

  16. Fates and roles of alkali and alkaline earth metal species during the pyrolysis and gasification of a Victorian lignite

    Energy Technology Data Exchange (ETDEWEB)

    Mody, D.; Wu, H.; Li, C. [Monash University, Vic. (Australia). CRC for Clean Power from Lignite, Dept. of Chemical Engineering

    2000-07-01

    The transformation of alkali and alkaline earth metal (AAEM) species in a Victorian lignite during the pyrolysis and subsequent gasification in CO{sub 2} was studied in a novel quartz fluidised-bed reactor. Lignite samples prepared by physically adding NaCl and ion-exchanging Na{sup +} and Ca{sup ++} into the lignite were used to investigate the effects of chemical forms and valency of the AAEM species in the substrate lignite on their transformation during pyrolysis and gasification. Carboxyl-bound Na was found to be less volatile than Na present as NaCl, but more volatile than carboxyl-bound Ca during pyrolysis at temperatures between 400 and 900{sup o}C. However, the carboxyl-bound Na was volatilised to a much greater extent than the carboxyl-bound Ca in the same lignite during pyrolysis. It was seen that the loading of NaCl into the lignite did not significantly affect the char reactivity in the fluidised-bed reactor at 900{sup o}C.

  17. Influence of compound deoxidation of steel with Al, Zr, rare earth metals, and Ti on properties of heavy castings

    Directory of Open Access Journals (Sweden)

    J. Senberger

    2012-01-01

    Full Text Available Heavy steel castings deoxidized with aluminium are sometimes brittle intercrystalline failed during their service along primary grain boundaries what is initiated by aluminium nitrides and so called conchoidal fractures are formed. The tendency to forming the conchoidal fractures depends in particular on cooling rate (the casting modulus, aluminium and nitrogen contents in steel. During deoxidation, when manufacturing heavy castings, the elements with high affinity to nitrogen, zirconium or titanium, are added to steel that would decrease nitrogen activity by the bond on stable nitrides. The formation of stable nitrides should reduce the tendency of steel to the formation of conchoidal fractures. Deoxidation was thermodynamically analyzed at presence of the mentioned elements. For particular conditions a probable course of deoxidation was estimated at test castings. The deoxidation course was checked by microanalysis of deoxidation products (inclusions. For service and experimental castings the anticipated composition of inclusions was compared. It has been proved that in heavy castings with high aluminium contents in steel under studied conditions neither the addition of zirconium nor of titanium nor of rare earth metals will prevent the formation of conchoidal fractures.

  18. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides.

    Science.gov (United States)

    Hereijgers, Bart P C; Weckhuysen, Bert M

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with all studied catalyst materials, however, the selectivity for hydrogen increased from 15 % to 51 % when going from the unpromoted to a BaO-promoted catalyst. The formation of the undesired byproducts CO, methane, and dimethyl ether was considerably reduced as well. The observed trend in catalyst performance follows the trend in increasing basicity of the studied promoter elements, indicating a chemical effect of the promoter material. Superior catalytic performance, in terms of H(2) and CO selectivity, was obtained with a Au/La(2)O(3) catalyst. At 300 degrees C the hydrogen selectivity reached 80 % with only 2 % CO formation, and the catalyst displayed a stable performance over at least 24 h on-stream. Furthermore, the formation of CO was found to be independent of the oxygen concentration in the feed. The commercial lanthanum oxide used in this study had a low specific surface area, which led to the formation of relative large gold particles. Therefore, the catalytic activity could be enhanced by decreasing the gold particle size through deposition on lanthanum oxide supported on high-surface-area alumina.

  19. Magnetic Resonance Imaging Distortion and Targeting Errors from Strong Rare Earth Metal Magnetic Dental Implant Requiring Revision.

    Science.gov (United States)

    Seong-Cheol, Park; Chong Sik, Lee; Seok Min, Kim; Eu Jene, Choi; Do Hee, Lee; Jung Kyo, Lee

    2016-12-22

    Recently, the use of magnetic dental implants has been re-popularized with the introduction of strong rare earth metal, for example, neodymium, magnets. Unrecognized magnetic dental implants can cause critical magnetic resonance image distortions. We report a case involving surgical failure caused by a magnetic dental implant. A 62-year-old man underwent deep brain stimulation for medically insufficiently controlled Parkinson's disease. Stereotactic magnetic resonance imaging performed for the first deep brain stimulation showed that the overdenture was removed. However, a dental implant remained and contained a neodymium magnet, which was unrecognized at the time of imaging; the magnet caused localized non-linear distortions that were the largest around the dental magnets. In the magnetic field, the subthalamic area was distorted by a 4.6 mm right shift and counter clockwise rotation. However, distortions were visually subtle in the operation field and small for distant stereotactic markers, with approximately 1-2 mm distortions. The surgeon considered the distortion to be normal asymmetry or variation. Stereotactic marker distortion was calculated to be in the acceptable range in the surgical planning software. Targeting errors, approximately 5 mm on the right side and 2 mm on the left side, occurred postoperatively. Both leads were revised after the removal of dental magnets. Dental magnets may cause surgical failures and should be checked and removed before stereotactic surgery. Our findings should be considered when reviewing surgical precautions and making distortion-detection algorithm improvements.

  20. Magnetic coupling at rare earth ferromagnet/transition metal ferromagnet interfaces: A comprehensive study of Gd/Ni.

    Science.gov (United States)

    Higgs, T D C; Bonetti, S; Ohldag, H; Banerjee, N; Wang, X L; Rosenberg, A J; Cai, Z; Zhao, J H; Moler, K A; Robinson, J W A

    2016-07-22

    Thin film magnetic heterostructures with competing interfacial coupling and Zeeman energy provide a fertile ground to study phase transition between different equilibrium states as a function of external magnetic field and temperature. A rare-earth (RE)/transition metal (TM) ferromagnetic multilayer is a classic example where the magnetic state is determined by a competition between the Zeeman energy and antiferromagnetic interfacial exchange coupling energy. Technologically, such structures offer the possibility to engineer the macroscopic magnetic response by tuning the microscopic interactions between the layers. We have performed an exhaustive study of nickel/gadolinium as a model system for understanding RE/TM multilayers using the element-specific measurement technique x-ray magnetic circular dichroism, and determined the full magnetic state diagrams as a function of temperature and magnetic layer thickness. We compare our results to a modified Stoner-Wohlfarth-based model and provide evidence of a thickness-dependent transition to a magnetic fan state which is critical in understanding magnetoresistance effects in RE/TM systems. The results provide important insight for spintronics and superconducting spintronics where engineering tunable magnetic inhomogeneity is key for certain applications.

  1. First-principles prediction of the magnetism of 4f rare-earth-metal-doped wurtzite zinc oxide

    Institute of Scientific and Technical Information of China (English)

    AG El Hachimi; H Zaari; A Benyoussef; M El Yadari; A El Kenz

    2014-01-01

    Electronic structure and magnetic properties of wurtzite ZnO semiconductor doped with rare earth (RE=La, Ce, Pr, Pm, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) atoms were studied using spin-polarized density functional theory based on the full-potential linear augmented plane wave (FP-LAPW) method as implemented in the Wien2k code. In this approach the generalized gradient ap-proximation (GGA) was used for the exchange-correlation (XC) potential. Our results showed that the substitution of RE ions in ZnO induced spins polarized localized states in the band gap. Moreover, the studied DMSs compounds retained half metallicity at dopant concentration x=0.625%for most of the studied elements, with 100%spin polarization at the Fermi level (EF). The total magnetic moments of these compounds existed due to RE 4f states present at EF, while small induced magnetic moments existed on other non-magnetic atoms as well. Finally, the energy difference between far and near configurations was investigated. It was found that the room temperature ferromagnetism was possible for RE-doped ZnO at near configuration. Since the RE-RE separation was long enough (far configuration) for magnetic coupling, the system became paramagnetic or antiferromagnetic ground state.

  2. Size of the fragment for crystal cluster SCF-X/sub /-SW calculations of alkaline earth metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Lobach, V.A.; Sobolev, A.B.; Shul' gin, B.V.

    Calculation of (A/sub x/B/sub y/) (x=1, 13; y=6, 14) clusters, corresponding to ideal crystals of alkaline earth metal oxides (AEMO) MgO, CaO, SrO by means of molecular cluster (MC) and crystal cluster (CC) SCF-X/sub /-SW method is carried out. MC method is not suitable for description of ideal AEMO electron structure due to long-range Coulomb interaction and potential cluster effect. Even in CC method at x < 13 and y < 14 (A/sub x/B/sub y/) cluster nonstoichiometry is inhibitory to the obtaining of satisfactory agreement with the experimental optical and X-ray spectra. (A13B14) and (B13A14) clusters satisfactorily reproduce partial composition of valence band (VB) and conduction band (CB), VB and CB widths, a fine structure of oxygen K-emission spectra in MgO and also experimental distribution of electron density. Sphere radii variation effect on the value of intersphere region error with muffin-tin averaging is considered.

  3. Rapid enrichment of rare-earth metals by carboxymethyl cellulose-based open-cellular hydrogel adsorbent from HIPEs template.

    Science.gov (United States)

    Zhu, Yongfeng; Wang, Wenbo; Zheng, Yian; Wang, Feng; Wang, Aiqin

    2016-04-20

    A series of monolithic open-cellular hydrogel adsorbents based on carboxymethylcellulose (CMC) were prepared through high internal phase emulsions (HIPEs) and used to enrich the rare-earth metals La(3+) and Ce(3+). The changes of pore structure, and the effects of pH, contact time, initial concentration on the adsorption performance were systematically studied. The results show that the as-prepared monolithic hydrogel adsorbents possess good open-cellular framework structure and have fast adsorption kinetics and high adsorption capacity for La(3+) and Ce(3+). The involved adsorption system can reach equilibrium within 30min and the maximal adsorption capacity is determined to be 384.62mg/g for La(3+) and 333.33mg/g for Ce(3+). Moreover, these porous hydrogel adsorbents show an excellent adsorptive reusability for La(3+) and Ce(3+) through five adsorption-desorption cycles. Such a pore hierarchy structure makes this monolithic open-cellular hydrogel adsorbent be an effective adsorbent for effective enrichment of La(3+) and Ce(3+) from aqueous solution.

  4. CO2 gasification reactivity of biomass char: catalytic influence of alkali, alkaline earth and transition metal salts.

    Science.gov (United States)

    Lahijani, Pooya; Zainal, Zainal Alimuddin; Mohamed, Abdul Rahman; Mohammadi, Maedeh

    2013-09-01

    This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3-7 wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5 wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5 wt% Na loaded char was calculated as 151.46 kJ/mol which was 53 kJ/mol lower than that of un-catalyzed char. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with {beta}-diketones

    Energy Technology Data Exchange (ETDEWEB)

    Imura, H. [Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512 (Japan)]. E-mail: imura@mx.ibaraki.ac.jp; Ebisawa, M. [Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512 (Japan); Kato, M. [Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512 (Japan); Ohashi, K. [Department of Environmental Sciences, Faculty of Science, Ibaraki University, Mito 310-8512 (Japan)

    2006-02-09

    The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE-{beta}-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants ({beta} {sub s,1}) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE-{beta}-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE-{beta}-diketone chelates and the cobalt(III) chelates.

  6. Impacts of Heterogeneous TiO2 and Al2O3 Composite Mesoporous Scaffold on Formamidinium Lead Trihalide Perovskite Solar Cells.

    Science.gov (United States)

    Numata, Youhei; Sanehira, Yoshitaka; Miyasaka, Tsutomu

    2016-02-01

    Heterogeneous TiO2 and Al2O3 composites were employed as a mesoporous scaffold in formamidinium lead trihalide (FAPbI3-xClx)-based perovskite solar cells to modify surface properties of a mesoporous layer. It was found that the quality and morphology of the perovskite film were strongly affected by the TiO2/Al2O3 ratio in the mesoporous film. The conversion efficiency of the perovskite solar cell was improved by using a composite of TiO2 and Al2O3 in comparison with TiO2- and Al2O3-based cells, yielding 11.0% for a cell with a 7:3 TiO2/Al2O3 composite. Our investigation shows a change of electron transport path depending on a composition ratio of insulating Al2O3 to n-type semiconducting TiO2 in a mesoporous layer.

  7. 1H and 23Na MAS NMR spectroscopy of cationic species in CO2 selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Science.gov (United States)

    Arévalo-Hidalgo, Ana G.; Dugar, Sneha; Fu, Riqiang; Hernández-Maldonado, Arturo J.

    2012-07-01

    The location of extraframework cations in Sr2+ and Ba2+ ion-exchanged SAPO-34 was estimated by means of 1H and 23Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO2 adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium.

  8. K2-111 b - a short period super-Earth transiting a metal poor, evolved old star

    Science.gov (United States)

    Fridlund, Malcolm; Gaidos, Eric; Barragán, Oscar; Persson, Carina M.; Gandolfi, Davide; Cabrera, Juan; Hirano, Teruyuki; Kuzuhara, Masayuki; Csizmadia, Sz.; Nowak, Grzegorz; Endl, Michael; Grziwa, Sascha; Korth, Judith; Pfaff, Jeremias; Bitsch, Bertram; Johansen, Anders; Mustill, Alexander J.; Davies, Melvyn B.; Deeg, Hans J.; Palle, Enric; Cochran, William D.; Eigmüller, Philipp; Erikson, Anders; Guenther, Eike; Hatzes, Artie P.; Kiilerich, Amanda; Kudo, Tomoyuki; MacQueen, Phillip; Narita, Norio; Nespral, David; Pätzold, Martin; Prieto-Arranz, Jorge; Rauer, Heike; Van Eylen, Vincent

    2017-07-01

    Context. From a light curve acquired through the K2 space mission, the star K2-111(EPIC 210894022) has been identified as possibly orbited by a transiting planet. Aims: Our aim is to confirm the planetary nature of the object and derive its fundamental parameters. Methods: We analyse the light curve variations during the planetary transit using packages developed specifically for exoplanetary transits. Reconnaissance spectroscopy and radial velocity observations have been obtained using three separate telescope and spectrograph combinations. The spectroscopic synthesis package SME has been used to derive the stellar photospheric parameters that were used as input to various stellar evolutionary tracks in order to derive the parameters of the system. The planetary transit was also validated to occur on the assumed host star through adaptive imaging and statistical analysis. Results: The star is found to be located in the background of the Hyades cluster at a distance at least 4 times further away from Earth than the cluster itself. The spectrum and the space velocities of K2-111 strongly suggest it to be a member of the thick disk population. The co-added high-resolution spectra show that that it is a metal poor ([Fe/H] = - 0.53 ± 0.05 dex) and α-rich somewhat evolved solar-like star of spectral type G3. We find Teff = 5730 ± 50 K, log g⋆ = 4.15 ± 0.1 cgs, and derive a radius of R⋆ = 1.3 ± 0.1 R⊙ and a mass of M⋆ = 0.88 ± 0.02 M⊙. The currently available radial velocity data confirms a super-Earth class planet with a mass of 8.6 ± 3.9 M⊕ and a radius of 1.9 ± 0.2 R⊕. A second more massive object with a period longer than about 120 days is indicated by a long-term radial velocity drift. Conclusions: The radial velocity detection together with the imaging confirms with a high level of significance that the transit signature is caused by a planet orbiting the star K2-111. This planet is also confirmed in the radial velocity data. A second more

  9. Effect of Rare Earth Elements (Er, Ho) on Semi-Metallic Materials (ScN) in an Applied Electric Field

    Science.gov (United States)

    Kim, Hyunjung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.

    2012-01-01

    The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV ( 0.2eV) respectively. This is less than that of undoped ScN (2.5 0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (Eg), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM

  10. Structures and Spectroscopy Studies of Two M(II-Phosphonate Coordination Polymers Based on Alkaline Earth Metals (M = Ba, Mg

    Directory of Open Access Journals (Sweden)

    Kui-Rong Ma

    2013-01-01

    Full Text Available The two examples of alkaline-earth M(II-phosphonate coordination polymers, [Ba2(L(H2O9]·3H2O (1 and [Mg1.5(H2O9]·(L-H21.5·6H2O (2 (H4L = H2O3PCH2N(C4H8NCH2PO3H2, N,N′-piperazinebis(methylenephosphonic acid, (L-H2 = O3PH2CHN(C4H8NHCH2PO3 have been hydrothermally synthesized and characterized by elemental analysis, FT-IR, PXRD, TG-DSC, and single-crystal X-ray diffraction. Compound 1 possesses a 2D inorganic-organic alternate arrangement layer structure built from 1D inorganic chains through the piperazine bridge, in which the ligand L−4 shows two types of coordination modes reported rarely at the same time. In 1, both crystallographic distinct Ba(1 and Ba(2 ions adopt 8-coordination two caps and 9-coordination three caps triangular prism geometry structures, respectively. Compound 2 possesses a zero-dimensional mononuclear structure with two crystallographic distinct Mg(II ions. Free metal cations   [MgO6]n2+ and uncoordinated anions (L-H2n2- are joined together by static electric force. Results of photoluminescent measurement indicate three main emission bands centered at 300 nm, 378.5 nm, and 433 nm for 1 and 302 nm, 378 nm, and 434.5 nm for 2 (λex=235 nm, respectively. The high energy emissions could be derived from the intraligand π∗-n transition stations of H4L (310 nm and 382 nm, λex=235 nm, while the low energy emission (>400 nm of 1-2 may be due to the coordination effect with metal(II ions.

  11. Synthesis and characterization of rare earth and transition metal doped BaMgF{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, S. [Industrial Research Limited, PO Box 31310, Lower Hutt 5040 (New Zealand); MacDiarmid Institute, SCPS, Victoria University of Wellington, PO Box 600, Wellington 6012 (New Zealand); Williams, G.V.M., E-mail: grant.williams@vuw.ac.nz [MacDiarmid Institute, SCPS, Victoria University of Wellington, PO Box 600, Wellington 6012 (New Zealand); Clarke, D. [Industrial Research Limited, PO Box 31310, Lower Hutt 5040 (New Zealand)

    2013-02-15

    BaMgF{sub 4} nanoparticles doped with Ce{sup 3+}, Eu{sup 3+}, Mn{sup 2+}, and Nd{sup 3+} have been successfully synthesized using a reverse microemulsion method. They form nanorods that aggregate into 'moustache' shaped clusters. All doped samples show photoluminescence where the Ce{sup 3+} and Eu{sup 3+} photoluminescence spectra are consistent with substitution onto different crystal sites, while only a single site was found for the Mn{sup 2+} doped sample. Mn{sup 2+} was successfully sensitized by Ce{sup 3+} in BaMgF{sub 4}:Mn{sup 2+}:Ce{sup 3+} nanoparticles. The Ce{sup 3+} PL lifetimes are strongly wavelength dependent, which could be due to different Ce{sup 3+} sites with different PL lifetimes as well as energy transfer between Ce{sup 3+} sites. Transparent thick polymer films containing nanoparticles have been made. The appearance of photoluminescence in rare earth and transition metal doped BaMgF{sub 4} nanoparticles and the ability to make transparent thick films means that the BaMgF{sub 4} nanoparticles have a range of potential applications that include optical amplification. - Highlights: Black-Right-Pointing-Pointer BaMgF{sub 4} nanorods synthesized using a reverse microemulsion method. Black-Right-Pointing-Pointer BaMgF{sub 4} nanorods successfully doped with luminescent ions. Black-Right-Pointing-Pointer Ce{sup 3+} and Eu{sup 3+} ions occupy two distinct crystal sites. Black-Right-Pointing-Pointer Efficient energy transfer from Ce{sup 3+} to Mn{sup 2+} is observed. Black-Right-Pointing-Pointer Transparent nanoparticle/PMMA polymer films were made.

  12. Ab Initio Quantum Mechanical Study of the Structure and Stability of the Alkaline Earth Metal Oxides and Peroxides

    Science.gov (United States)

    Königstein, Markus; Catlow, C. Richard A.

    1998-10-01

    We report a detailed computationally study of the stability of the alkaline earth metal peroxidesMO2(M=Ba, Sr, Ca, Mg, Be) with respect to decomposition into the corresponding oxidesMOand molecular oxygen using Hartree-Fock and density functional theory (DFT) techniques. A comparison between calculated and experimental binding energies indicates that the DFT method is most suitable for a correct description of the peroxide bond. The DFT reaction energies for the peroxide decompositionMO2→MO+{1}/{2}O2show that only BaO2and SrO2are thermodynamically stable compounds, while CaO2(in the calcium carbide structure), MgO2, and BeO2(in the pyrite structure) are energetically unstable with reaction energies of -24.7, -26.8, and -128.7kJ/mol, respectively, and are therefore unlikely to exist as pure compounds. The published calcium carbide structure for CaO2is probably incorrect, at least for pure calcium peroxide, since apart from the thermodynamical instability the compound is more stable in the pyrite structure by 25.5 kJ/mol. Our analysis suggests that the water and/or hydrogen peroxide content of experimentally prepared MgO2samples is necessary for the stabilization of the structure, while BeO2is clearly unstable under ambient conditions. We studied also the effect of the zero point energies and the entropies on the decomposition free energies and, for this purpose, performed atomistic lattice simulations based on interatomic potentials, which we derived from ourab initiodata; the results indicate a negligible effect of the zero point energies, while the entropy terms favor the decomposition reaction by ca. 20 kJ/mol at 298.15 K.

  13. Ab initio quantum mechanical study of the structure and stability of the alkaline earth metal oxides and peroxides

    Energy Technology Data Exchange (ETDEWEB)

    Koenigstein, M.; Catlow, C.R.A. [Royal Institution of Great Britain, London (United Kingdom). Davy Faraday Research Lab.

    1998-10-01

    The authors report a detailed computational study of the stability of the alkaline earth metal peroxides MO{sub 2} (M = Ba, Sr, Ca, Mg, Be) with respect to decomposition into the corresponding oxides Mo and molecular oxygen using Hartree-Fock and density functional theory (DFT) techniques. A comparison between calculated and experimental binding energies indicates that the DFT method is most suitable for a correct description of the peroxide bond. The DFT reaction energies for the peroxide decomposition MO{sub 2} {yields} MO + {1/2}O{sub 2} show that only BaO{sub 2} and SrO{sub 2} are thermodynamically stable compounds, while CaO{sub 2} (in the calcium carbide structure), MgO{sub 2}, and BeO{sub 2} (in the pyrite structure) are energetically unstable with reaction energies of {minus}24.7, {minus}26.8, and {minus}128.7 kJ/mol, respectively, and are therefore unlikely to exist as pure compounds. The published calcium carbide structure for CaO{sub 2} is probably incorrect, at least for pure calcium peroxide, since apart from the thermodynamical instability the compound is more stable in the pyrite structure by 25.5 kJ/mol. The analysis suggests that the water and/or hydrogen peroxide content of experimentally prepared MgO{sub 2} samples is necessary for the stabilization of the structure, while BeO{sub 2} is clearly unstable under ambient conditions. The authors studied also the effect of the zero point energies and the entropies on the decomposition free energies and, for this purpose, performed atomistic lattice simulations based on interatomic potentials, which they derived from their ab initio data; the results indicate a negligible effect of the zero point energies, while the entropy terms favor the decomposition reaction by ca. 20 kJ/mol at 298.15 K.

  14. Removal of toxic and alkali/alkaline earth metals during co-thermal treatment of two types of MSWI fly ashes in China.

    Science.gov (United States)

    Yu, Jie; Qiao, Yu; Jin, Limei; Ma, Chuan; Paterson, Nigel; Sun, Lushi

    2015-12-01

    This study aims to vaporize heavy metals and alkali/alkaline earth metals from two different types of fly ashes by thermal treatment method. Fly ash from a fluidized bed incinerator (HK fly ash) was mixed with one from a grate incinerator (HS fly ash) in various proportions and thermally treated under different temperatures. The melting of HS fly ash was avoided when treated with HK fly ash. Alkali/alkaline earth metals in HS fly ash served as Cl-donors to promote the vaporization of heavy metals during thermal treatment. With temperature increasing from 800 to 900°C, significant amounts of Cl, Na and K were vaporized. Up to 1000°C in air, less than 3% of Cl and Na and less than 5% of K were retained in ash. Under all conditions, Cd can be vaporized effectively. The vaporization of Pb was mildly improved when treated with HS fly ash, while the effect became less pronounced above 900°C. Alkali/alkaline earth metals can promote Cu vaporization by forming copper chlorides. Comparatively, Zn vaporization was low and only slightly improved by HS fly ash. The low vaporization of Zn could be caused by the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4. Under all conditions, less than 20% of Cr was vaporized. In a reductive atmosphere, the vaporization of Cd and Pb were as high as that in oxidative atmosphere. However, the vaporization of Zn was accelerated and that of Cu was hindered because the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4 and copper chloride was depressed in reductive atmosphere. Copyright © 2015. Published by Elsevier Ltd.

  15. Counterion influence on the vibrational wavenumbers in ternary and quaternary metal hydride salts, A2MH6 (A = alkali metal, alkaline earth, and lanthanides; M = Ir, Fe, Ru, Os, Pt, Mn).

    Science.gov (United States)

    Gilson, Denis F R; Moyer, Ralph O

    2012-02-06

    The wavenumbers of the ν(3) metal-hydrogen stretching mode (T(1u)) in the IR spectra of both ternary and quaternary hexahydrido salts of transition metals from groups 7 to 10 ([Mn(I)H(6)](5-), [Fe(II)H(6)](4-), [Ru(II)H(6)](4-), [Os(II)H(6)](4-), [Ir(III)H(6)](3-), and [Pt(IV)H(6)](2-)) depend linearly upon the ionization energies of the counterions (alkali metal, alkaline earth, and lanthanide) with a separate line for each metal. This relationship provides quantitative support for the charge-transfer mechanism for explaining the stabilities of these compounds.

  16. Enhanced Electroresponse of Alkaline Earth Metal-Doped Silica/Titania Spheres by Synergetic Effect of Dispersion Stability and Dielectric Property.

    Science.gov (United States)

    Yoon, Chang-Min; Lee, Seungae; Cheong, Oug Jae; Jang, Jyongsik

    2015-09-01

    A series of alkaline earth metal-doped hollow SiO2/TiO2 spheres (EM-HST) are prepared as electrorheological (ER) materials via sonication-mediated etching method with various alkaline earth metal hydroxides as the etchant. The EM-HST spheres are assessed to determine how their hollow interior and metal-doping affects the ER activity. Both the dispersion stability and the dielectric properties of these materials are greatly enhanced by the proposed one-step etching method, which results in significant enhancement of ER activity. These improvements are attributed to increased particle mobility and interfacial polarization originating from the hollow nature of the EM-HST spheres and the effects of EM metal-doping. In particular, Ca-HST-based ER fluid exhibits ER performance which is 7.1-fold and 3.1-fold higher than those of nonhollow core/shell silica/titania (CS/ST) and undoped hollow silica/titania (HST)-based ER fluids, respectively. This study develops a versatile and simple approach to enhancing ER activity through synergetic effects arising from the combination of dispersion stability and the unique dielectric properties of hollow EM-HST spheres. In addition, the multigram scale production described in this experiment can be an excellent advantage for practical and commercial ER application.

  17. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals.

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V; Goddard, William A

    2016-04-05

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

  18. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals

    Science.gov (United States)

    Liu, Yuanyue; Merinov, Boris V.; Goddard, William A., III

    2016-04-01

    It is well known that graphite has a low capacity for Na but a high capacity for other alkali metals. The growing interest in alternative cation batteries beyond Li makes it particularly important to elucidate the origin of this behavior, which is not well understood. In examining this question, we find a quite general phenomenon: among the alkali and alkaline earth metals, Na and Mg generally have the weakest chemical binding to a given substrate, compared with the other elements in the same column of the periodic table. We demonstrate this with quantum mechanics calculations for a wide range of substrate materials (not limited to C) covering a variety of structures and chemical compositions. The phenomenon arises from the competition between trends in the ionization energy and the ion-substrate coupling, down the columns of the periodic table. Consequently, the cathodic voltage for Na and Mg is expected to be lower than those for other metals in the same column. This generality provides a basis for analyzing the binding of alkali and alkaline earth metal atoms over a broad range of systems.

  19. Rare earth metals influence on mechanical properties and crack resistance of GP240GH and G17CrMo5-5 cast steels

    Directory of Open Access Journals (Sweden)

    M. Gajewski

    2009-10-01

    Full Text Available This paper presents results of research on modification influence of REM on mechanical properties and crack resistance of GP240GH cast carbon steel and G17CrMo5-5 high-temperature cast steel. The tests have been performed on successive industrial melts. The rare earth metals were put into the ladle during tapping of heat melt from the furnace. Each time ca 2000 kg of liquid metals were modified. Because of this the amount of sulphur in the cast steel was decreased and the non-metallic inclusion morphology was significantly changed. There were tested mechanical properties (Re,Rm, plastic properties (A5,Z and impact strength (KV, and on the basis of the three-point bend test the KJC stress intensity factor was evaluated. It was noticed that the REM modification brings essential increase of impact strength as well as fracture toughness determined by KJC factor.

  20. Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

    2016-07-01

    An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

  1. The influence of alkaline earth metal equilibria on the rheological, melting and textural properties of Cheddar cheese.

    Science.gov (United States)

    Cooke, Darren R; McSweeney, Paul L H

    2013-11-01

    The total calcium content of cheese, along with changes in the equilibrium between soluble and casein (CN)-bound calcium during ripening can have a major impact on its rheological, functional and textural properties; however, little is known about the effect of other alkaline earth metals. NaCl was partially substituted with MgCl2 or SrCl2 (8·7 and 11·4 g/kg curd, respectively) at the salting stage of cheesemaking to study their effects on cheese. Three cheeses were produced: Mg supplemented (+Mg), Sr supplemented (+Sr) and a control Cheddar cheese. Ca, Mg and Sr contents of cheese and expressible serum obtained therefrom were determined by atomic absorption spectroscopy. Addition of Mg2+ or Sr2+ had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg2+ and Sr2+ became CN-bound. The level of CN-bound Mg was higher in the +Mg cheese than the control throughout ripening. The level of CN-bound Ca and Mg decreased during ripening in all cheeses, as did % CN-bound Sr in the +Sr cheese. The presence of Sr2+ increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg2+ had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher G' at 70 °C and a lower LTmax than the control and +Mg cheeses throughout ripening. The +Sr cheese had significantly lower meltability compared with the control and +Mg cheeses after 2 months of ripening. Hardness values of the +Sr cheese were higher at week 2 than the +Mg and control cheeses. Addition of Mg2+ did not influence the physical properties of cheese. Supplementing cheese with Sr appeared to have effects analogous to those previously reported for increasing Ca content. Sr2+ may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.

  2. Ultrafast electron, lattice and spin dynamics on rare earth metal surfaces. Investigated with linear and nonlinear optical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Radu, I.E.

    2006-03-15

    This thesis presents the femtosecond laser-induced electron, lattice and spin dynamics on two representative rare-earth systems: The ferromagnetic gadolinium Gd(0001) and the paramagnetic yttrium Y(0001) metals. The employed investigation tools are the time-resolved linear reflectivity and second-harmonic generation, which provide complementary information about the bulk and surface/interface dynamics, respectively. The femtosecond laser excitation of the exchange-split surface state of Gd(0001) triggers simultaneously the coherent vibrational dynamics of the lattice and spin subsystems in the surface region at a frequency of 3 THz. The coherent optical phonon corresponds to the vibration of the topmost atomic layer against the underlying bulk along the normal direction to the surface. The coupling mechanism between phonons and magnons is attributed to the modulation of the exchange interaction J between neighbour atoms due to the coherent lattice vibration. This leads to an oscillatory motion of the magnetic moments having the same frequency as the lattice vibration. Thus these results reveal a new type of phonon-magnon coupling mediated by the modulation of the exchange interaction and not by the conventional spin-orbit interaction. Moreover, we show that coherent spin dynamics in the THz frequency domain is achievable, which is at least one order of magnitude faster than previously reported. The laser-induced (de)magnetization dynamics of the ferromagnetic Gd(0001) thin films have been studied. Upon photo-excitation, the nonlinear magneto-optics measurements performed in this work show a sudden drop in the spin polarization of the surface state by more than 50% in a <100 fs time interval. Under comparable experimental conditions, the time-resolved photoemission studies reveal a constant exchange splitting of the surface state. The ultrafast decrease of spin polarization can be explained by the quasi-elastic spin-flip scattering of the hot electrons among spin

  3. Promoting alkali and alkaline-earth metals on MgO for enhancing CO2 capture by first-principles calculations.

    Science.gov (United States)

    Kim, Kiwoong; Han, Jeong Woo; Lee, Kwang Soon; Lee, Won Bo

    2014-12-07

    Developing next-generation solid sorbents to improve the economy of pre- and post-combustion carbon capture processes has been challenging for many researchers. Magnesium oxide (MgO) is a promising sorbent because of its moderate sorption-desorption temperature and low heat of sorption. However, its low sorption capacity and thermal instability need to be improved. Various metal-promoted MgO sorbents have been experimentally developed to enhance the CO2 sorption capacities. Nevertheless, rigorous computational studies to screen an optimal metal promoter have been limited to date. We conducted first-principles calculations to select metal promoters of MgO sorbents. Five alkali (Li-, Na-, K-, Rb-, and Cs-) and 4 alkaline earth metals (Be-, Ca-, Sr-, and Ba-) were chosen as a set of promoters. Compared with the CO2 adsorption energy on pure MgO, the adsorption energy on the metal-promoted MgO sorbents is higher, except for the Na-promoter, which indicates that metal promotion on MgO is an efficient approach to enhance the sorption capacities. Based on the stabilized binding of promoters on the MgO surface and the regenerability of sorbents, Li, Ca, and Sr were identified as adequate promoters among the 9 metals on the basis of PW91/GGA augmented with DFT+D2. The adsorption energies of CO2 on metal-promoted MgO sorbents for Li, Ca, and Sr atoms are -1.13, -1.68, and -1.48 eV, respectively.

  4. Identifying the presence of a disulfide linkage in peptides by the selective elimination of hydrogen disulfide from collisionally activated alkali and alkaline earth metal complexes.

    Science.gov (United States)

    Kim, Hugh I; Beauchamp, J L

    2008-01-30

    We report a new method for identifying disulfide linkages in peptides using mass spectrometry. This is accomplished by collisional activation of singly charged cationic alkali and alkaline earth metal complexes, which results in the highly selective elimination of hydrogen disulfide (H2S2). Complexes of peptides possessing disulfide bonds with sodium and alkaline earth metal are generated using electrospray ionization (ESI). Isolation followed by collision induced dissociation (CID) of singly charged peptide complexes results in selective elimination of H2S2 to leave newly formed dehydroalanine residues in the peptide. Further activation of the product yields sequence information in the region previously short circuited by the disulfide bond. For example, singly charged magnesium and calcium ion bound complexes of [Lys8]-vasopressin exhibit selective elimination of H2S2 via low-energy CID. Further isolation of the product followed by CID yields major b- and z-type fragments revealing the peptide sequence in the region between the newly formed dehydroalanine residues. Numerous model peptides provide mechanistic details for the selective elimination of H2S2. The process is initiated starting with a metal stabilized enolate anion at Cys, followed by cleavage of the S-C bond. An examination of the peptic digest of insulin provides an example of the application of the selective elimination of H2S2 for the identification of peptides with disulfide linkages. The energetics and mechanisms of H2S2 elimination from model compounds are investigated using density functional theory (DFT) calculations.

  5. Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups.

    Science.gov (United States)

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Jones, Phil; Paull, Brett

    2013-02-08

    A commercially available porous silica monolithic column (Onyx Monolithic Si, 100 mm×4.6 mm I.D.) was 'in-column' covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14 min with a flow rate of just 0.8 mL/min. Detection was achieved using spectrophotometric detection at 540 nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165 M LiNO(3) eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000 N/m, for Zn(2+), Mn(2+) and Cd(2+), respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns.

  6. The influence of organic structure and rare earth metal cation on the corrosion efficiency observed on AS1020 steel compared with La(4OHCin3

    Directory of Open Access Journals (Sweden)

    Marianne Seter

    2015-01-01

    Full Text Available Whilst the corrosion protection of steel in aqueous chloride environments by the rare earth inhibitor lanthanum 4-hydroxycinnamate is well known, the influence of the structural variation of the organic component as well as the nature of the metal centre has not previously been addressed. Herein we show that praseodymium 4-hydroxy cinnamate is comparable to its lanthanum counterpart in aqueous solution. On the other hand, cerium 4-hydroxycinnamate and lanthanum 2-hydroxycinnamate show poor corrosion protection performance while lanthanum 3-hydroxycinnamate provides a level of inhibition between these. These differences are shown to be related to the speciation in solution and are postulated to be linked to steric influences which are likely to affect the bonding environment within the rare earth compound itself, as well as its bonding with the steel substrate.

  7. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    Science.gov (United States)

    Jia, You-Hua; Zhong, Biao; Yin, Jian-Ping

    2009-03-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material.

  8. Production of Synthesis Gas via Methane Reforming with CO2 on Ni/SiO2 Catalysts Promoted by Alkali and Alkaline Earth Metals

    Institute of Scientific and Technical Information of China (English)

    陈平; 侯昭胤; 郑小明

    2005-01-01

    Ni/SiO2 catalysts promoted by alkali metals K and Cs or alkaline earth metals Mg, Ca, Sr and Ba were prepared, characterized by H2-TPR and XRD, and used for the production of synthesis gas via methane reforming with CO2. Though K and Cs promoted Ni catalysts could eliminate coke deposition, the reforming activity of these promoted catalysts was decreased heavily. Mg and Ca promoted Ni/SiO2 catalysts exhibited excellent coke resistance ability with minor loss of the reforming activity of Ni/SiO2. Ba showed poor coke resistance ability and small amount of Sr increased the formation of coke. The possible mechanism of these promoters was discussed.

  9. Influence of rare-earth metal doping on the catalytic performance of CuO-CeO2 for the preferential oxidation of CO in excess hydrogen

    Institute of Scientific and Technical Information of China (English)

    Zhigang Liu; Renxian Zhou; Xiaoming Zheng

    2008-01-01

    Doping of different rare-earth metals(Pr,Nd,Y and La)had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation(PROX)Of CO in excess hydrogen.As for Pr,the doping enhanced the catalytic activity of CuO-CeO2 for PROX.For example,the CO conversion over the above catalyst for PROX was higher than 99%at 120℃.Especially.the doping of Pr widened the temperature window by 20℃ over CuO-CeO2 with 99%CO conversion.For Nd,Y and La,the doping depressed the catalytic activity of CuO-CeO2 for PROX.However,the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.

  10. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films.

    Science.gov (United States)

    Mikheev, Evgeny; Hauser, Adam J; Himmetoglu, Burak; Moreno, Nelson E; Janotti, Anderson; Van de Walle, Chris G; Stemmer, Susanne

    2015-11-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices.

  11. Metals and Rare Earth Elements in polar aerosol as specific markers of natural and anthropogenic aerosol sources areas and atmospheric transport processes

    Science.gov (United States)

    Giardi, Fabio; Becagli, Silvia; Caiazzo, Laura; Cappelletti, David; Grotti, Marco; Malandrino, Mery; Salzano, Roberto; Severi, Mirko; Traversi, Rita; Udisti, Roberto

    2016-04-01

    Metals and Rare Earth Elements (REEs) in the aerosol have conservative properties from the formation to the deposition and can be useful to identify and quantify their natural and anthropic sources and to study the atmospheric transport processes. In spite of their importance relatively little is known about metals and especially REEs in the Artic atmosphere due to their low concentration in such environment. The present work reports the first attempt to determine and interpret the behaviour of metals and REEs in polar aerosol at high temporal resolution. Daily PM10 samples of arctic atmospheric particulate were collected on Teflon filters, during six spring-summer campaigns, since 2010, in the laboratory of Gruvebadet in Ny Ålesund (78°56' N, 11°56' E, Svalbard Islands, Norway). Chemical analyses were carried out through Inductively Coupled Plasma Mass Spectrometer provided with a desolvation nebulizer inlet system, allowing to reduce isobaric interferences and thus to quantify trace and ultra-trace metals in very low concentration in the Arctic aerosol samples. The results are useful in order to study sources areas, transport processes and depositional effects of natural and anthropic atmospheric particulate reaching the Arctic from southern industrialized areas; moreover, the observed seasonal trends give information about the different impact of natural and anthropic emissions driven by phenomena such as the Arctic Haze and the melting of the snow. In particular Rare Earth Elements (often in the ppt range) can be considered as soil's fingerprints of the particulate source areas and their determination, together with air-mass backtrajectory analysis, allow to identify dust source areas for the arctic mineral aerosol.

  12. Simultaneous spectrophotometric determination of thorium and rare earth metals with m-carboxychlorophosphonazo (CPAmK) and cetylpyridinium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Chunggin Hsu; Ximan Lian; Jiaomai Pan (East China Normal Univ., Shanghai, SH (China))

    1991-09-01

    Th and rare earth elements (REE) react with m-carboxychlorophosphonazo (CPAmK) in the absence of cetylpyridinium chloride (CPC) to form colour complexes. In the presence of CPC, REE-complexes are not formed because of micellar masking, while Th gives a more sensitive reaction with CPAmK. Most of the foreign ions are tolerated in considerable amounts; 360-1000-fold amounts of rare earths do not interfere with the determination of Th. The optimum conditions of the complex-formation reactions and the compositions of Th-CPAmK complexes are described. A simple method is proposed for simultaneous determination of Th and rare earths without previous separation. (author).

  13. Developments in the use of rare earth metal complexes as efficient catalysts for ring-opening polymerization of cyclic esters used in biomedical applications

    Science.gov (United States)

    Cota, Iuliana

    2017-04-01

    Biodegradable polymers represent a class of particularly useful materials for many biomedical and pharmaceutical applications. Among these types of polyesters, poly(ɛ-caprolactone) and polylactides are considered very promising for controlled drug delivery devices. These polymers are mainly produced by ring-opening polymerization of their respective cyclic esters, since this method allows a strict control of the molecular parameters (molecular weight and distribution) of the obtained polymers. The most widely used catalysts for ring-opening polymerization of cyclic esters are tin- and aluminium-based organometallic complexes; however since the contamination of the aliphatic polyesters by potentially toxic metallic residues is particularly of concern for biomedical applications, the possibility of replacing organometallic initiators by novel less toxic or more efficient organometallic complexes has been intensively studied. Thus, in the recent years, the use of highly reactive rare earth initiators/catalysts leading to lower polymer contamination has been developed. The use of rare earth complexes is considered a valuable strategy to decrease the polyester contamination by metallic residues and represents an attractive alternative to traditional organometallic complexes.

  14. Ground-state oxygen holes and the metal-insulator transition in the negative charge-transfer rare-earth nickelates

    Science.gov (United States)

    Bisogni, Valentina; Catalano, Sara; Green, Robert J.; Gibert, Marta; Scherwitzl, Raoul; Huang, Yaobo; Strocov, Vladimir N.; Zubko, Pavlo; Balandeh, Shadi; Triscone, Jean-Marc; Sawatzky, George; Schmitt, Thorsten

    2016-10-01

    The metal-insulator transition and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding of these materials remains elusive. Here we combine X-ray absorption and resonant inelastic X-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of rare-earth nickelates, taking NdNiO3 thin film as representative example. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for abundant oxygen holes in the ground state of these materials. Using cluster calculations and Anderson impurity model interpretation, we show that distinct spectral signatures arise from a Ni 3d8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a conventional positive charge-transfer picture, but instead exhibit a negative charge-transfer energy in line with recent models interpreting the metal-insulator transition in terms of bond disproportionation.

  15. Robust and Porous β-Diketiminate-Functionalized Metal–Organic Frameworks for Earth-Abundant-Metal-Catalyzed C–H Amination and Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Thacker, Nathan C.; Lin, Zekai; Zhang, Teng; Gilhula, James C.; Abney, Carter W.; Lin, Wenbin (UC)

    2016-05-27

    We have designed a strategy for postsynthesis installation of the β-diketiminate (NacNac) functionality in a metal–organic framework (MOF) of UiO-topology. Metalation of the NacNac-MOF (I) with earth-abundant metal salts afforded the desired MOF-supported NacNac-M complexes (M = Fe, Cu, and Co) with coordination environments established by detailed EXAFS studies. The NacNac-Fe-MOF catalyst, I•Fe(Me), efficiently catalyzed the challenging intramolecular sp3 C–H amination of a series of alkyl azides to afford α-substituted pyrrolidines. The NacNac-Cu-MOF catalyst, I•Cu(THF), was effective in promoting the intermolecular sp3 C–H amination of cyclohexene using unprotected anilines to provide access to secondary amines in excellent selectivity. Finally, the NacNac-Co-MOF catalyst, I•Co(H), was used to catalyze alkene hydrogenation with turnover numbers (TONs) as high as 700 000. All of the NacNac-M-MOF catalysts were more effective than their analogous homogeneous catalysts and could be recycled and reused without a noticeable decrease in yield. The NacNac-MOFs thus provide a novel platform for engineering recyclable earth-abundant-element-based single-site solid catalysts for many important organic transformations.

  16. Analysis of trace rare earth elements in misch metal by means of ITP-PIXE (isotachophoresis - Particle Induced X-ray Emission) method

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian-Ying; Hirokawa, Takeshi; Nishiyama, Fumitaka; Kimura, Goji; Kiso, Yoshiyuki; Ito, Kazuaki; Shoto, Eiji [Hiroshima Univ., Higashi-Hiroshima (Japan). Faculty of Engineering

    1993-12-31

    A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE (isotachophoresis - Particle Induced X-ray Emission): The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotachophoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca.10% accuracy was achieved for each minor element except for Sm(23%), Gd(17%) and Yb(18%). The analytical results by ITP-PIXE were compared with those by means of ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry). (author).

  17. MB82- (M=Be,Mg,Ca,Sr,and Ba):Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Complexes involving planar octacoordinate alkaline earth metal atoms in the centers of eight-membered boron rings have been investigated by two density functional theory (DFT) methods.BeB82-with D8h symmetry is predicted to be stable,both geometrically and electronically,since a good match is achieved between the size of the central beryllium atom and the eight-membered boron ring.By contrast,the other alkaline earth metal atoms cannot be stabilized in the center of a planar eight-membered boron ring because of their large radii.By following the out-of-plane imaginary vibrational frequency,pyramidal C8v MgB82-,CaB82-,SrB82-,and BaB82-structures are obtained.The presence of delocalized π and σ valence molecular orbitals in D8h BeB82-gives rise to aromaticity,which is reflected by the value of the nucleus-independent chemical shift.The D8h BeB82-structure is confirmed to be the global minimum on the potential energy surface.

  18. Triel Bonds, π-Hole-π-Electrons Interactions in Complexes of Boron and Aluminium Trihalides and Trihydrides with Acetylene and Ethylene.

    Science.gov (United States)

    Grabowski, Sławomir J

    2015-06-19

    MP2/aug-cc-pVTZ calculations were performed on complexes of aluminium and boron trihydrides and trihalides with acetylene and ethylene. These complexes are linked through triel bonds where the triel center (B or Al) is characterized by the Lewis acid properties through its π-hole region while π-electrons of C2H2 or C2H4 molecule play the role of the Lewis base. Some of these interactions possess characteristics of covalent bonds, i.e., the Al-π-electrons links as well as the interaction in the BH3-C2H2 complex. The triel-π-electrons interactions are classified sometimes as the 3c-2e bonds. In the case of boron trihydrides, these interactions are often the preliminary stages of the hydroboration reaction. The Quantum Theory of "Atoms in Molecules" as well as the Natural Bond Orbitals approach are applied here to characterize the π-hole-π-electrons interactions.

  19. Triel Bonds, π-Hole-π-Electrons Interactions in Complexes of Boron and Aluminium Trihalides and Trihydrides with Acetylene and Ethylene

    Directory of Open Access Journals (Sweden)

    Sławomir J. Grabowski

    2015-06-01

    Full Text Available MP2/aug-cc-pVTZ calculations were performed on complexes of aluminium and boron trihydrides and trihalides with acetylene and ethylene. These complexes are linked through triel bonds where the triel center (B or Al is characterized by the Lewis acid properties through its π-hole region while π-electrons of C2H2 or C2H4 molecule play the role of the Lewis base. Some of these interactions possess characteristics of covalent bonds, i.e., the Al-π-electrons links as well as the interaction in the BH3-C2H2 complex. The triel-π-electrons interactions are classified sometimes as the 3c-2e bonds. In the case of boron trihydrides, these interactions are often the preliminary stages of the hydroboration reaction. The Quantum Theory of “Atoms in Molecules” as well as the Natural Bond Orbitals approach are applied here to characterize the π-hole-π-electrons interactions.

  20. Synthesis, characterization, antibacterial and antifungal studies of some transition and rare earth metal complexes of N-benzylidene-2-hydroxybenzohydrazide

    Directory of Open Access Journals (Sweden)

    T.K. Chondhekar

    2011-12-01

    Full Text Available The solid complexes of Cu(II, Co(II, Mn(II, La(III and Ce(III were prepared from bidentate Schiff base, N-benzylidene-2-hydroxybenzohydrazide. The Schiff base ligand was synthesized from 2-hyhdroxybenzohydrazide and benzaldehyde. These metal complexes were characterized by molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, FTIR, 1H-NMR, UV-Vis and mass spectroscopy. The analytical data of these metal complexes showed metal:ligand ratio of 1:2. The physico-chemical study supports the presence of square planar geometry around Cu(II and octahedral geometry around Mn(II, Co(II, La(III and Ce(III ions. The IR spectral data reveal that the ligand behaves as bidentate with ON donor atom sequence towards central metal ion. The molar conductance values of metal complexes suggest their non-electrolyte nature. The X-ray diffraction data suggest monoclinic crystal system for these complexes. Thermal behavior (TG/DTA and kinetic parameters calculated by Coats-Redfern method are suggestive of more ordered activated state in complex formation. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungicidal activity against Aspergillus niger and Trichoderma.

  1. High mobilization of arsenic, metals and rare earth elements in seepage waters driven by respiration of old allochthonous organic carbon.

    Science.gov (United States)

    Weiske, Arndt; Schaller, Jörg; Hegewald, Tilo; Machill, Susanne; Werner, Ingo; Dudel, E Gert

    2013-12-01

    Metal and metalloid mobilization processes within seepage water are of major concern in a range of water reservoir systems. The mobilization process of arsenic and heavy metals within a dam and sediments of a drinking water reservoir was investigated. Principle component analysis (PCA) on time series data of seepage water showed a clear positive correlation of arsenic with iron and DOC (dissolved organic carbon), and a negative correlation with nitrate due to respiratory processes. A relationship of reductive metal and metalloid mobilization with respiration of old carbon was shown. The system is influenced by sediment layers as well as a recent DOC input from degraded ombrotrophic peatbogs in the catchment area. The isotopic composition ((12)C, (13)C and (14)C) of DOC is altered along the path from basin to seepage water, but no significant changes in structural parameters (LC-OCD-OND, FT-IR) could be seen. DIC (dissolved inorganic carbon) in seepage water partly originates from respiratory processes, and a higher relationship of it with sediment carbon than with the DOC inventory of infiltrating water was found. This study revealed the interaction of respiratory processes with metal and metalloid mobilization in sediment water flows. In contrast to the presumption that emerging DOC via respiratory processes mainly controls arsenic and metal mobilization it could be shown that the presence of aged carbon compounds is essential. The findings emphasize the importance of aged organic carbon for DOC, DIC, arsenic and metal turnover.

  2. Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie [Department of Chemistry, Maynooth University, National University of Ireland—Maynooth, County Kildare (Ireland)

    2016-01-28

    Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅ RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.

  3. Mechanochemical synthesis, structure, and properties of solid solutions of alkaline earth metal fluorides: Ma1-xMbxF2 (M: Ca, Sr, Ba)

    Science.gov (United States)

    Heise, M.; Scholz, G.; Düvel, A.; Heitjans, P.; Kemnitz, E.

    2016-10-01

    The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1-xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1-xSrxF2 and Ba1-xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F- ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.

  4. Effect of H2O on metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe: Implications for the oxidation state of the Earth and Mars

    Science.gov (United States)

    Clesi, V.; Bouhifd, M. A.; Bolfan-Casanova, N.; Manthilake, G.; Fabbrizio, A.; Andrault, D.

    2016-11-01

    This study investigates the metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe-C-Ni-Co-Si-S in a multi-anvil over a range of P, T, fO2 and water content (5-20 GPa, 2073-2500 K, from 1 to 5 log units below the iron-wüstite (IW) buffer and for XH2O varying from 500 ppm to 1.5 wt%). By comparing the present experiments with the available data sets on dry systems, we observes that the effect of water on the partition coefficients of moderately siderophile elements is only moderate. For example, for iron we observed a decrease in the partition coefficient of Fe (Dmet/silFe) from 9.5 to 4.3, with increasing water content of the silicate melt, from 0 to 1.44 wt%, respectively. The evolution of metal-silicate partition coefficients of Ni, Co, V, Cr, Mn and Fe are modelled based on sets of empirical parameters. These empirical models are then used to refine the process of core segregation during accretion of Mars and the Earth. It appears that the likely presence of 3.5 wt% water on Mars during the core-mantle segregation could account for ∼74% of the FeO content of the Martian mantle. In contrast, water does not play such an important role for the Earth; only 4-6% of the FeO content of its mantle could be due to the water-induced Fe-oxidation, for a likely initial water concentration of 1.8 wt%. Thus, in order to reproduce the present-day FeO content of 8 wt% in the mantle, the Earth could initially have been accreted from a large fraction (between 85% and 90%) of reducing bodies (similar to EH chondrites), with 10-15% of the Earth's mass likely made of more oxidized components that introduced the major part of water and FeO to the Earth. This high proportion of enstatite chondrites in the original constitution of the Earth is consistent with the 17O,48Ca,50Ti,62Ni

  5. Synthesis and infrared spectra of alkaline earth metal carbonates formed by the reaction of metal salts with urea at high temperature

    Indian Academy of Sciences (India)

    S M Teleb; D El-Sayed Nassr; E M Nour

    2004-12-01

    The metal carbonate, MCO3 (M = Ca, Sr and Ba), was synthesized by a novel method of reacting aqueous solution of each of Ca2+, Sr2+ and Ba2+ salts with urea at high temperature, ∼ 80°C. The reaction products were characterized through elemental analysis and infrared spectra. The infrared spectra of the products are the same as those of the corresponding commercially obtained carbonates. A general reaction describing the formation of MCO3 is proposed.

  6. 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

    2017-03-27

    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.

  7. Investigation of Surfactant-Stain-Metal Interaction: Naphthochrome Green/Cetyltrimethylammonium Bromide/Rare Earths Ternary Complexation

    Institute of Scientific and Technical Information of China (English)

    郑立新; 沈荣; 郜洪文

    2003-01-01

    The ternary interaction of naphthochrome green (NCG) with cetyltrimethylammonium bromide (CTAB) and rare earths (Res: Yb, Dy, Er and Eu) has been investigated with the microsurface adsorption-spectral correction technique (MSASC). The aggregation of NCG on CTAB obeys the Langmuir isothermal adsorption. The enrichment of NCG on CTAB and the presence of NaCl sensitize the complexation between Res and NCG. Both the binary aggregate and the ternary complex were characterized in the presence and absence of NaCl at pH 8.30 at 20 and 40℃.

  8. Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal

    Institute of Scientific and Technical Information of China (English)

    SONG Ming-zhi; ZHU Lan-ying; GAO Xi-ke; DOU Jian-min; SUN De-zhi

    2005-01-01

    Thermodynamic parameters of complexation of naphto- 15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.

  9. Volatilisation of alkali and alkaline earth metallic species during the gasification of a Victorian brown coal in CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Quyn, Dimple Mody; Li, Chun-Zhu [CRC for Clean Power from Lignite, Department of Chemical Engineering, PO Box 36, Monash University, Victoria 3800 (Australia); Hayashi, Jun-ichiro [Centre for Advanced Research of Energy Conversion Materials, Hokkaido University, N13-W8, Kita-ku, Sapporo 060-8628 (Japan)

    2005-08-25

    A Victorian brown coal was gasified in a bench-scale quartz fluidised-bed/fixed-bed reactor in order to study the volatilisation of Na, Ca, and Mg during devolatilisation and gasification and their roles in the reactivity of chars. It was found that the majority of Na was volatilised at 900 {sup o}C under all conditions and that a Na retention limit was achieved in the char with the progress of CO{sub 2} gasification. In some cases, the presence of CO{sub 2} during devolatilisation enhanced the Na retention in the char. In contrast, the retention of Ca (and Mg) was unaffected by CO{sub 2} during devolatilisation at 900C but decreased drastically upon nascent char gasification. The fundamental differences in volatilisation between the alkali and alkaline earth metallic species are discussed in this paper.

  10. The coordination complex structures and hydrogen bonding in the three-dimensional alkaline earth metal salts (Mg, Ca, Sr and Ba) of (4-aminophenyl)arsonic acid.

    Science.gov (United States)

    Smith, Graham; Wermuth, Urs D

    2017-01-01

    (4-Aminophenyl)arsonic acid (p-arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4-aminophenyl)arsonic acid (p-arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4-aminophenyl)arsonate] tetrahydrate, [Mg(H2O)6](C6H7AsNO3)·4H2O, (I), catena-poly[[[diaquacalcium]-bis[μ2-hydrogen (4-aminophenyl)arsonato-κ(2)O:O']-[diaquacalcium]-bis[μ2-hydrogen (4-aminophenyl)arsonato-κ(2)O:O

  11. Volatilisation of alkali and alkaline earth metallic species during the pyrolysis of biomass: differences between sugar cane bagasse and cane trash.

    Science.gov (United States)

    Keown, Daniel M; Favas, George; Hayashi, Jun-ichiro; Li, Chun-Zhu

    2005-09-01

    Sugar cane bagasse and cane trash were pyrolysed in a novel quartz fluidised-bed/fixed-bed reactor. Quantification of the Na, K, Mg and Ca in chars revealed that pyrolysis temperature, heating rate, valence and biomass type were important factors influencing the volatilisation of these alkali and alkaline earth metallic (AAEM) species. Pyrolysis at a slow heating rate (approximately 10 K min(-1)) led to minimal (often biomass samples. Fast heating rates (>1000 K s(-1)), encouraging volatile-char interactions with the current reactor configuration, resulted in the volatilisation of around 80% of Na, K, Mg and Ca from bagasse during pyrolysis at 900 degrees C. Similar behaviour was observed for monovalent Na and K with cane trash, but the volatilisation of Mg and Ca from cane trash was always restricted. The difference in Cl content between bagasse and cane trash was not sufficient to fully explain the difference in the volatilisation of Mg and Ca.

  12. Universal behavior of chalcogenides of rare-earth metals in the transition to a state with intermediate valence at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Tsiok, O. B.; Khvostantsev, L. G.; Brazhkin, V. V., E-mail: brazhkin@hppi.troitsk.ru [Russian Academy of Sciences, Vereshchagin Institute of High-Pressure Physics (Russian Federation)

    2015-06-15

    Precision measurements of resistivity, thermopower, and volume are performed for TmS, TmSe, and TmTe under a hydrostatic pressure up to 8 GPa. Comparison of the transport properties and volume of TmTe and SmTe in the valence transition region demonstrates a complete analogy up to quantitative coincidence. It is shown that the thermopower of all thulium and samarium chalcogenides in the lattice collapse region and in subsequent rearrangement of the electron spectrum in a wide range of pressures follow a universal dependence corresponding the passage of the Fermi level through the peak of the density of states (DOS). The results are considered in the context of ideas about the exciton nature of the intermediate valence in chalcogenides of rare-earth metals.

  13. Hydrogen adsorption in a highly stable porous rare-earth metal-organic framework: sorption properties and neutron diffraction studies.

    Science.gov (United States)

    Luo, Junhua; Xu, Hongwu; Liu, Yun; Zhao, Yusheng; Daemen, Luke L; Brown, Craig; Timofeeva, Tatiana V; Ma, Shengqian; Zhou, Hong-Cai

    2008-07-30

    A highly stable porous lanthanide metal-organic framework, Y(BTC)(H2O).4.3H2O (BTC = 1,3,5-benzenetricarboxylate), with pore size of 5.8 A has been constructed and investigated for hydrogen storage. Gas sorption measurements show that this porous MOF exhibits highly selective sorption behaviors of hydrogen over nitrogen gas molecules and can take up hydrogen of about 2.1 wt % at 77 K and 10 bar. Difference Fourier analysis of neutron powder diffraction data revealed four distinct D2 sites that are progressively filled within the nanoporous framework. Interestingly, the strongest adsorption sites identified are associated with the aromatic organic linkers rather than the open metal sites, as occurred in previously reported MOFs. Our results provide for the first time direct structural evidence demonstrating that optimal pore size (around 6 A, twice the kinetic diameter of hydrogen) strengthens the interactions between H2 molecules and pore walls and increases the heat of adsorption, which thus allows for enhancing hydrogen adsorption from the interaction between hydrogen molecules with the pore walls rather than with the normally stronger adsorption sites (the open metal sites) within the framework. At high concentration H2 loadings (5.5 H2 molecules (3.7 wt %) per Y(BTC) formula), H2 molecules form highly symmetric novel nanoclusters with relatively short H2-H2 distances compared to solid H2. These observations are important and hold the key to optimizing this new class of rare metal-organic framework (RMOF) materials for practical hydrogen storage applications.

  14. Assessment of metal, trace and rare earth element concentrations in a sedimentary profile from Ponte Nova reservoir, Sao Paulo state, Brazil, by NAA

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, Flavio R.; Bordon, Isabella C.C.L.; Silva, Paulo S.C.; Favaro, Deborah I.T., E-mail: flavio@baquara.com, E-mail: defavaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Silva, Sharlleny A.; Franklin, Robson L.; Ferreira, Francisco J., E-mail: shasilva@sp.gov.br, E-mail: rfranklin@sp.gov.br [Companhia Ambiental do Estado de Sao Paulo (ELAI/CETESB), SP (Brazil). Setor de Quimica Inorganica

    2015-07-01

    Ponte Nova reservoir, located in the upper basin of the Tiete River in the southern region of Sao Paulo State, covers an area of 25.7 km{sup 2} and drains an area of 320 km{sup 2}. It was built in 1972 to control the rivers flow in the Metropolitan Region of Sao Paulo (MRSP) and water supply. A 30 cm sediment core was collected in the dam in August 2014, sliced at every 2.5 cm. Instrumental neutron activation analysis (INAA) was applied to the sediment samples to determine some major (Fe, K and Na), trace (As, Ba, Br, Co, Cr, Cs, Hf, Rb, Sb, Sc, Ta, Tb, Th, U and Zn) and rare earth (Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) elements. The enrichment factor (EF) and Igeo were applied to the results by using NASC (North American Shale Composite) as reference values for sediment contamination index assessment. An EF>1.5 was obtained for As, Hf, Rb, Ta, Th, U, and rare earths Ce, Eu, La, Nd and Sm when NASC values were used, but only for Br, when the last layer concentration values were used as reference values. Similar results were obtained for the Igeo index. For semi-metal As and metals Cr and Zn concentration values were compared to oriented values from Environmental Canada (TEL and PEL) only Cr exceeded TEL value in some slices of the profile. These results may indicate that there is no anthropogenic contribution for the elements analyzed in this reservoir. Multivariate statistical analysis was applied to the results. (author)

  15. Diversity, metal resistance and uranium sequestration abilities of bacteria from uranium ore deposit in deep earth stratum.

    Science.gov (United States)

    Islam, Ekramul; Sar, Pinaki

    2016-05-01

    Metal resistance and uranium (U) sequestration abilities of bacteria residing in subsurface U ore was investigated using 122 pure culture strains isolated through enrichment. The cumulative frequencies of isolates resistant to each metal tested were as follows: As(V), 74%; Zn, 58%; Ni, 53%; Cd, 47%; Cr(VI), 41%; Co, 40%; Cu, 20%; and Hg, 4%. 16S rRNA gene analysis revealed that isolated bacteria belonged to 14 genera with abundance of Arthrobacter, Microbacterium, Acinetobacter and Stenotrophomonas. Cobalt did not interfere with the growth of most of the bacterial isolates belonging to different groups while U allowed growth of four different genera of which Stenotrophomonas and Microbacterium showed high U tolerance. Interestingly, tolerance to Ni, Zn, Cu, and Hg was observed only in Microbacterium, Arthrobacter, Paenibacillus¸ and Acinetobacter, respectively. However, Microbacterium was found to be dominant when isolated from other five different metal enrichments including U. Uranium removal study showed that 84% of the test bacteria could remove more than 50mgUg(-1) dry weight from 80 or 160mgL(-1) U within 48h. In general, Microbacterium, Arthrobacter and Acinetobacter could remove a higher amount of U. High resolution transmission electron microscopy (HRTEM) study of U exposed cells revealed that accumulated U sequestered mostly around the cell periphery. The study highlights that indigenous U ore deposit bacteria have the potential to interact with U, and thus could be applied for bioremediation of U contaminated sites or wastes.

  16. Syntheses, Characterization and Antitumour Activities of Rare Earth Metal Complexes with 2-(((4,6-dimethyl)-2-Pyrimidinyl)thio)-Acetic Acid

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Eight rare earth metal (Ⅲ) complexes with 2-(((4,6-dimethyl)-2-pyrimidinyl)thio)-acetic acid, LnL3*nH2O [HL=2-(((4,6-dimethyl)-2-pyrimidinyl)thio)-acetic acid; Ln=La, Ce, Pr, Nd, Sm Eu, Gd, Tb; n=4 or 5], were prepared and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR and 1H-NMR. The results reveal that carboxyl group of the ligand coordinates with rare earth ions in bidentate mode after deprotonated. The water molecules exist as crystal water in the complexes. The anti-tumour activities of HL and some complexes were tested by both the MTT and SRB methods. The results show that the suppression ratios of some complexes against the tested tumour cells (HL-60 human leukemia cell lines, BGC-823 human gastric carcinoma cell lines, hela human cervix adenocarcinoma cell lines and Bel-7402 human hepatic carcinoma cell lines) are superior to HL.

  17. Phase characteristics of rare earth elements in metallic fuel for a sodium-cooled fast reactor by injection casting

    Science.gov (United States)

    Kuk, Seoung Woo; Kim, Ki Hwan; Kim, Jong Hwan; Song, Hoon; Oh, Seok Jin; Park, Jeong-Yong; Lee, Chan Bock; Youn, Young-Sang; Kim, Jong-Yun

    2017-04-01

    Uranium-zirconium-rare earth (U-Zr-RE) fuel slugs for a sodium-cooled fast reactor were manufactured using a modified injection casting method, and investigated with respect to their uniformity, distribution, composition, and phase behavior according to RE content. Nd, Ce, Pr, and La were chosen as four representative lanthanide elements because they are considered to be major RE components of fuel ingots after pyroprocessing. Immiscible layers were found on the top layers of the melt-residue commensurate with higher fuel slug RE content. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) data showed that RE elements in the melt-residue were distributed uniformly throughout the fuel slugs. RE element agglomeration did not contaminate the fuel slugs but strongly affected the RE content of the slugs.

  18. Thermal stability of the anionic sigma complexes of 2,4,6-trinitroanisole with the methylates of the alkaline-earth metals

    Energy Technology Data Exchange (ETDEWEB)

    Glaz, A.I.; Soldatova, T.A.; Golopolosova, T.V.; Gitis, S.S.

    1987-09-10

    The study of the stability of the 1,1-dimethoxy-2,4,6-trinitrocyclohexadienates of the alkali metals when they are heated in air showed that their temperature of decomposition and the heat effect of the process are dependent on the nature of the cation. Our study centered on the thermal decomposition of the products resulting from the addition of the methylates of calcium, strontium, and barium to 2,4,6-trinitroanisole. For a quantitative assessment of the process we used the combined methods of differential-thermal analysis and differential thermogravimetry. The anionic sigma-complexes of 2,4,6-trinitroanisole with the methylates of the alkaline-earth metals decompose on heating into the corresponding picrates; at the same time, when one passes from the calcium slat to the strontium and barium salts the decomposition temperature and the heat effect of the process show a drop which is linked to the structure both of the complexes and of the picrates forming therefrom.

  19. Removal of ammonia from aqueous solutions by catalytic oxidation with copper-based rare earth composite metal materials: catalytic performance, characterization, and cytotoxicity evaluation

    Institute of Scientific and Technical Information of China (English)

    Chang-Mao Hung

    2011-01-01

    Ammonia (NH3) has an important use in the chemical industry and is widely found in industrial wastewater.For this investigation of copper-based rare earth composite metal materials,aqueous solutions containing 400 mg/L of ammonia were oxidized in a batch-bed reactor with a catalyst prepared by the co-precipitation of copper nitrate,lanthanum nitrate and cerium nitrate.Barely any of the dissolved ammonia was removed by wet oxidation without a catalyst,but about 88% of the ammonia was reduced during wet oxidation over the catalysts at 423 K with an oxygen partial pressure of 4.0 MPa.The catalytic redox behavior was determined by cyclic voltammetry (CV).Furthermore,the catalysts were characterized using thermogravimetric analyzer (TGA) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX),which showed that the catalytic behavior was related to the metal oxide properties of the catalyst.In addition,the copper-lanthanum-cerium composite-induced cytotoxicity in the human lung MRC-5 cell line was tested,and the percentage cell survival was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro.No apparent cytotoxicity was observed when the human lung cells were exposed to the copper-lanthanum-cerium composite.

  20. Fundamentals of Liquid Processing in Low Earth Orbit: From Thermophysical Properties to Microstructure Formation in Metallic Alloys

    Science.gov (United States)

    Fecht, Hans-Jörg; Wunderlich, Rainer K.

    2017-08-01

    Materials science, as an interdisciplinary field with significant attention paid to nanoscience and nanotechnology in recent years, is generally concerned with the synthesis, atomic structure, chemical element distribution and various favorable properties of solid materials and structures. While solid-state processing conditions are generally insensitive to gravity effects, liquid-state processing depends considerably on gravity, leading to strong impact of interfacial phenomena (liquid/solid, liquid/liquid), momentum, heat and mass transport on solidification patterns, as well as further consequences regarding phase selection during solidification and growth conditions, segregation, etc. In this regard, it is interesting to note that almost 100% of all metallic products are, at some stage, produced through solidification and casting processes. Experiments on metallic liquids excluding the effects of gravity—which is achievable through processing in space, thus reducing gravity effects to micro-levels—allow benchmark experiments and the opening of a new realm of experimental possibilities to investigate basic features of the liquid state. The basics and several experimental results are discussed including recent experiments on long time scales under high temperature and containerless processing conditions on board the International Space Station.

  1. Iron complex-catalyzed ammonia-borane dehydrogenation. A potential route toward B-N-containing polymer motifs using earth-abundant metal catalysts.

    Science.gov (United States)

    Baker, R Tom; Gordon, John C; Hamilton, Charles W; Henson, Neil J; Lin, Po-Heng; Maguire, Steven; Murugesu, Muralee; Scott, Brian L; Smythe, Nathan C

    2012-03-28

    Ammonia-borane (NH(3)BH(3), AB) has garnered interest as a hydrogen storage material due to its high weight percent hydrogen content and ease of H(2) release relative to metal hydrides. As a consequence of dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability to control this process and dictate the identity of the generated polymer opens up the possibility of the targeted synthesis of new materials. While precious metals have been used in this regard, the ability to construct such materials using earth-abundant metals such as Fe presents a more economical approach. Four Fe complexes containing amido and phosphine supporting ligands were synthesized, and their reactivity with AB was examined. Three-coordinate Fe(PCy(3))[N(SiMe(3))(2)](2) (1) and four-coordinate Fe(DEPE)[N(SiMe(3))(2)](2) (2) yield a mixture of (NH(2)BH(2))(n) and (NHBH)(n) products with up to 1.7 equiv of H(2) released per AB but cannot be recycled (DEPE = 1,2-bis(diethylphosphino)ethane). In contrast, Fe supported by a bidentate P-N ligand (4) can be used in a second cycle to afford a similar product mixture. Intriguingly, the symmetric analogue of 4 (Fe(N-N)(P-P), 3), only generates (NH(2)BH(2))(n) and does so in minutes at room temperature. This marked difference in reactivity may be the result of the chemistry of Fe(II) vs Fe(0).

  2. Role of Mononuclear Rare Earth Metal Complexes in Promoting the Hydrolysis of 2-Hydroxypropyl p-Nitrophenyl Phosphate

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; LIN Hai; LIN Hua-Kuan

    2007-01-01

    Two long-chain multidentate ligands: 2,9-di-(n-2',5',8'-triazanonyl)-1,10-phenanthroline (L1) and 2,9-di-(n-4',7',10'-triazaundecyl)-1,10-phenanthroline (L2) were synthesized. The hydrolytic kinetics of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) catalyzed by the complexes of L1 or L2 with La(Ⅲ) or Gd(Ⅲ) have been studied lytic effect of GdL1 was the best among the four complexes for hydrolysis of HPNP. Its kLnLH-1, kLnL and pKa are structure of the ligands and the properties of the metal ions, and deduced the catalysis mechanism.

  3. Dark-state suppression and optimization of laser cooling and fluorescence in a trapped alkaline-earth-metal single ion

    CERN Document Server

    Lindvall, T; Tittonen, I; Madej, A A; 10.1103/PhysRevA.86.033403

    2012-01-01

    We study the formation and destabilization of dark states in a single trapped 88Sr+ ion caused by the cooling and repumping laser fields required for Doppler cooling and fluorescence detection of the ion. By numerically solving the time-dependent density matrix equations for the eight-level system consisting of the sublevels of the 5s 2S1/2, 5p 2P1/2, and 4d 2D3/2 states, we analyze the different types of dark states and how to prevent them in order to maximize the scattering rate, which is crucial for both the cooling and the detection of the ion. The influence of the laser linewidths and ion motion on the scattering rate and the dark resonances is studied. The calculations are then compared with experimental results obtained with an endcap ion trap system located at the National Research Council of Canada and found to be in good agreement. The results are applicable also to other alkaline earth ions and isotopes without hyperfine structure.

  4. Adsorption and growth morphology of rare-earth metals on graphene studied by ab initio calculations and scanning tunneling microscopy

    Science.gov (United States)

    Liu, Xiaojie; Wang, C. Z.; Hupalo, M.; Yao, Y. X.; Tringides, M. C.; Lu, W. C.; Ho, K. M.

    2010-12-01

    Adsorption of rare-earth (RE) adatoms (Nd, Gd, Eu, and Yb) on graphene was studied by first-principles calculations based on the density-functional theory. The calculations show that the hollow site of graphene is the energetically favorable adsorption site for all the RE adatoms studied. The adsorption energies and diffusion barriers of Nd and Gd on graphene are found to be larger than those of Eu and Yb. Comparison with scanning tunneling microscopy experiments for Gd and Eu epitaxially grown on graphene confirms these calculated adsorption and barrier differences, since fractal-like islands are observed for Gd and flat-topped crystalline islands for Eu. The formation of flat Eu islands on graphene can be attributed to its low diffusion barrier and relatively larger ratio of adsorption energy to its bulk cohesive energy. The interactions between the Nd and Gd adatoms and graphene cause noticeable in-plane lattice distortions in the graphene layer. Adsorption of the RE adatoms on graphene also induces significant electric dipole and magnetic moments.

  5. Research into processes of production of hydrides of materials containing rare-earth metals and their corrosion

    Science.gov (United States)

    Sofronov, V. L.; Kartashov, E. Y.; Molokov, P. B.; Zhiganov, A. N.; Kalaev, M. E.

    2017-01-01

    Production of permanent magnets on basis of rare earth elements (REE) is implemented by means of powder metallurgy, therefore a technologically important operation is the multistage mechanical crushing of materials to the extent of domains. The promising technique of crushing of magnetic materials is their consistent hydrogenation-dehydrogenation that allows obtaining nano-dispersed powders which are stable enough in air. Hydrogenation apparatuses, as opposed to conventional grinding machines, do not comprise motion works and their producing capacity is much higher. Hydrogenation process does not require any additional preparation of materials and it excludes undermilling and overmilling as well as material oxidation. The paper presents the results of investigation on the temperature effect on the hydrogenation process of Nd-Fe alloys. The study results on the corrosion stability of ligature hydrides under various conditions are also given. Kinetic parameters of the hydrogenation process of ligatures are determined. The phase composition of corrosion products is detected. Guidelines on hydride powder storage are given.

  6. The capacity of hydrous fluids to transport and fractionate incompatible elements and metals within the Earth's mantle

    Science.gov (United States)

    Adam, John; Locmelis, Marek; Afonso, Juan Carlos; Rushmer, Tracy; Fiorentini, Marco L.

    2014-06-01

    silicate melts and aqueous fluids are thought to play critical roles in the chemical differentiation of the Earth's crust and mantle. Yet their relative effects are poorly constrained. We have addressed this issue by measuring partition coefficients for 50 trace and minor elements in experimentally produced aqueous fluids, coexisting basanite melts, and peridotite minerals. The experiments were conducted at 1.0-4.0 GPa and 950-1200°C in single capsules containing (either 40 or 50 wt %) H2O and trace element-enriched basanite glass. This allowed run products to be easily identified and analyzed by a combination of electron microprobe and LAM-ICP-MS. Fluid and melt compositions were reconstructed from mass balances and published solubility data for H2O in silicate melts. Relative to the basanite melt, the solutes from H2O-fluids are enriched in SiO2, alkalis, Ba, and Pb, but depleted in FeO, MgO, CaO, and REE. With increasing pressure, the mutual solubility of fluids and melts increases rapidly with complete miscibility between H2O and basanitic melts occurring between 3.0 and 4.0 GPa at 1100°C. Although LREE are favored over HREE in the fluid phase, they are less soluble than the HFSE (Nb, Ta, Zr, Hf, and Ti). Thus, the relative depletions of HFSE that are characteristic of arc magmas must be due to a residual phase that concentrates HFSE (e.g., rutile). Otherwise, H2O-fluids have the capacity to impart many of the geochemical characteristics that distinguish some rocks and melts from the deep mantle lithosphere (e.g., MARID and lamproites).

  7. Metal, trace and rare earth element assessment in a sedimentary profile from Promissao reservoir, Sao Paulo state, Brazil, by INAA

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sharlleny A.; Franklin, Robson L., E-mail: shasilva@sp.gov.br [Companhia Ambiental do Estado de Sao Paulo (ELAI/CETESB), SP (Brazil). Setor de Quimica Inorganica; Luiz-Silva, Wanilson [Universidade Estadual de Campinas (DGRN/UNICAMP), SP (Brazil). Instituto de Geociencias. Departamento de Geologia e Recursos Naturais; Favaro, Deborah I.T., E-mail: defavaro@ipen.gov.br [Instituto de Pesquisas Energeticas e Nucleares (LAN/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Laboratorio de Analise por Ativacao Neutronica

    2015-07-01

    In the present study the preliminary results for the Promissao reservoir, situated in the Lower Tiete region covering a little more than 1% of the SP state population, is characterized by intense agropastoral activities. Its operations for generating electrical energy started in 1975. It is located at Tiete River and its hydrographic basin has a drainage area of 530 km{sup 2}. The total extension of the reservoir is 110 km along the Tiete River, with a medium depth of 20 m. A core sampler was used and a 33 cm sediment core was collected from the dam in January 2013, sliced at every 2.5 cm, totaling 13 samples. Instrumental neutron activation analysis was applied to the sediment samples in order to determine some major (Fe, K, and Na), trace (As, Ba, Br, Co, Cr, Cs, Hf, Rb, Sb, Sc, Ta, Tb, Th, U, and Zn) and rare earth elements (Ce, Eu, La, Lu, Nd, Sm, Tb, and Yb). The enrichment factor (EF) was applied to the results obtained by using North American Shale Composite, Upper Continental Crust and the concentration values of the last layer of this profile as reference values for sediment contamination index assessment. When the results for As, Cr, and Zn were compared to threshold effect level (TEL) and probable effect level (PEL) oriented values, sediments from 0-10 cm exceeded the TEL values for As (5.9 mg kg{sup -1}), all samples exceeded the PEL values for Cr (90 mg kg{sup -1}), and all samples had much lower values than TEL values for Zn (123 mg kg{sup -1}). (author)

  8. Rare-earth metal methylidene complexes with Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 core structure.

    Science.gov (United States)

    Schädle, Dorothea; Meermann-Zimmermann, Melanie; Maichle-Mössmer, Cäcilia; Schädle, Christoph; Törnroos, Karl W; Anwander, Reiner

    2015-11-07

    Trinuclear rare-earth metal methylidene complexes with a Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 structural motif were synthesized by applying three protocols. Polymeric [LuMe3]n (1-Lu) reacts with the sterically demanding amine H[NSiMe3(Ar)] (Ar = C6H3iPr2-2,6) in tetrahydrofuran via methane elimination to afford isolable monomeric [NSiMe3(Ar)]LuMe2(thf)2 (4-Lu). The formation of trinuclear rare-earth metal tetramethyl methylidene complexes [NSiMe3(Ar)]3Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3(thf)3 (7-Ln; Ln = Y, Ho, Lu) via reaction of [LnMe3]n (1-Ln; Ln = Y, Ho, Lu) with H[NSiMe3(Ar)] is proposed to occur via an "intermediate" species of the type [NSiMe3(Ar)]LnMe2(thf)x and subsequent C-H bond activation. Applying Lappert's concept of Lewis base-induced methylaluminate cleavage, compounds [NSiMe3(Ar)]Ln(AlMe4)2 (5-Ln; Ln = Y, La, Nd, Ho) were converted into methylidene complexes 7-Ln (Ln = Y, Nd, Ho) in the presence of tetrahydrofuran. Similarly, tetramethylgallate complex [NSiMe3(Ar)]Y(GaMe4)2 (6-Y) could be employed as a synthesis precursor for 7-Y. The molecular composition of complexes 4-Ln, 5-Ln, 6-Y and 7-Ln was confirmed by elemental analyses, FTIR spectroscopy, (1)H and (13)C NMR spectroscopy (except for holmium derivatives) and single-crystal X-ray diffraction. The Tebbe-like reactivity of methylidene complex 7-Nd with 9-fluorenone was assessed affording oxo complex [NSiMe3(Ar)]3Nd3(μ3-O)(μ2-Me)4(thf)3 (8-Nd). The synthesis of 5-Ln yielded [NSiMe3(Ar)]2Ln(AlMe4) (9-Ln; Ln = La, Nd) as minor side-products, which could be obtained in moderate yields when homoleptic Ln(AlMe4)3 were treated with two equivalents of K[NSiMe3(Ar)].

  9. Rare earth metal doped CeO2-based catalytic materials for diesel soot oxidation at lower temperatures

    Institute of Scientific and Technical Information of China (English)

    A Rangaswamy; Putla Sudarsanam; Benjaram M Reddy

    2015-01-01

    In this work, the influence of trivalent rare-earth dopants (Sm and La) on the structure-activity properties of CeO2 was thor-oughly studied for diesel soot oxidation. For this, an optimized 40%of Sm and La was incorporated into the CeO2 using a facile co-precipitation method from ultra-high dilute aqueous solutions. A systematic physicochemical characterization was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brumauer-Emmett-teller method (BET) surface area, X-ray pho-toelectron spectroscopy (XPS), Raman, and H2-temperature programmed reduction (TPR) techniques. The soot oxidation efficiency of the catalysts was investigated using a thermogravimetric method. The XRD results suggested the formation of nanocrystalline sin-gle phase CeO2-Sm2O3 and CeO2-La2O3 solid solutions. The Sm-and La-doped CeO2 materials exhibited smaller crystallite size and higher BET surface area compared with the pure CeO2. Owing to the difference in the oxidation states of the dopants (Sm3+and La3+) and the Ce4+, a number of oxygen vacancies were generated in CeO2-Sm2O3 and CeO2-La2O3 samples. The H2-TPR studies evidenced the improved reducible nature of the CeO2-Sm2O3 and CeO2-La2O3 samples compared with the CeO2. It was found that the addition of Sm and La to the CeO2 outstandingly enhanced its catalytic efficiency for the oxidation of diesel soot. The observed 50%soot con-version temperatures for the CeO2-Sm2O3, CeO2-La2O3 and CeO2 were~790, 843 and 864 K (loose contact), respectively, and similar activity order was also found under the tight contact condition. The high soot oxidation efficacy of the CeO2-Sm2O3 sample was at-tributed to numerous catalytically favourable properties, like smaller crystallite size, larger surface area, abundant oxygen vacancies, and superior reducible nature.

  10. Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)) Derived from Molecular Precursors and Doped with Eu(3+) Ions.

    Science.gov (United States)

    Drąg-Jarząbek, Anna; John, Łukasz; Petrus, Rafał; Kosińska-Klähn, Magdalena; Sobota, Piotr

    2016-03-24

    The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high-purity binary metal oxide perovskites MZrO3 (M=Ba(2+), Sr(2+), Ca(2+)). Single-source molecular precursors [Ba4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2(η(2) -HOR)2 (HOR)2 Cl4], [Sr4 Zr2 (μ6 -O)(μ3 ,η(2)-OR)8 (OR)2 (HOR)4 Cl4], [Ca4 Zr2 (μ6-O)(μ3 ,η(2)-OR)8 (OR)2 Cl4], and [Ca6 Zr2 (μ2 ,η(2)-OR)12 (μ-Cl)2 (η(2) -HOR)4 Cl6 ]⋅8 CH2 Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2 ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2 CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray diffraction. The compounds were then thermally decomposed to MCl2 /MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskite-like oxide particles of 40-80 nm in size. Luminescence studies on Eu(3+)-doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology.

  11. 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

  12. Magnesium substitutions in rare-earth metal germanides with the Gd5Si4 type. Synthesis, structure determination and magnetic properties of RE5-xMgxGe4 (RE=Gd-Tm, Lu and Y)

    Energy Technology Data Exchange (ETDEWEB)

    Sarrao, J L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Tobash, P H [UNIV. OF DE; Bobev, S [UNIV. OF DE

    2009-01-01

    A series of magnesium-substituted rare-earth metal germanides with a general formula RE{sub 5-x}Mg{sub x}Ge{sub 4} (x {approx} 1.0-2.3; RE =Gd-Tm, Lu, Y) have been synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. These compounds crystallize with the common Gd{sub 5}Si{sub 4} type in the orthorhombic space group Pnma (No. 62; Z =4; Pearson's code oP36) and do not appear to undergo temperature-induced crystallographic phase transitions down to 120 K. Replacing rare-earth metal atoms with Mg, up to nearly 45 % at., reduces the valence electron count and is clearly expressed in the subtle changes of the Ge-Ge and metal-metal bonding. Magnetization measurements as a function of the temperature and the applied field reveal complex magnetic structures at cryogenic temperatures, and Curie-Weiss paramagnetic behavior at higher temperatures. The observed local moment magnetism is consistent with RE+ ground states in all cases. In the magnetically ordered phases, the magnetization cannot reach saturation in fields up to 50 kOe. The structural trends across the series and the variations of hte magnetic properties as a function of the Mg content are also discussed. KEYWORDS: Rare-earth intermetallics, germanides, crystal structure,Gd{sub 5}Si{sub 4} type.

  13. Development of electrolytic process in molten salt media for light rare-earth metals production. The metallic cerium electrodeposition; Desenvolvimento de processo de eletrolise em meio de sais fundidos para a producao de metais de terras-raras leves. A obtencao do cerio metalico

    Energy Technology Data Exchange (ETDEWEB)

    Restivo, T.A.G.

    1994-12-31

    The development of molten salt process and the respective equipment aiming rare-earth metals recovery was described. In the present case, the liquid cerium metal electrodeposition in a molten electrolytes of cerium chloride and an equimolar mixture of sodium and potassium chlorides in temperatures near 800{sup C} was studied. Due the high chemical reactivity of the rare-earth metals in the liquid state and their molten halides, an electrolytic cell was constructed with controlled atmosphere, graphite crucibles and anodes and a tungsten cathode. The electrolytic process variables and characteristics were evaluated upon the current efficiency and metallic product purity. Based on this evaluations, were suggested some alterations on the electrolytic reactor design and upon the process parameters. (author). 90 refs, 37 figs, 20 tabs.

  14. Dimethyl ether synthesis via methanol and syngas over rare earth metals modified zeolite Y and dual Cu-Mn-Zn catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dingfeng Jin; Bing Zhu; Zhaoyin Hou; Jinhua Fei; Hui Lou; Xiaoming Zheng [Zhejiang University, Hangzhou (China). Institute of Catalysis, Department of Chemistry

    2007-12-15

    A series of zeolite Y modified with La, Ce, Pr, Nd, Sm and Eu were prepared via ion-exchange, and characterized by XRD, FT-IR and NH{sub 3}-TPD. It was found that these rare earth metals were encapsulated in the supercage of zeolite Y and resulted in its enhanced acidity. Among them, La-, Ce-, Pr- and Nd-modified zeolite Y exhibited higher activity and stability (than pure HY) for methanol dehydration to dimethyl ether (DME). For DME synthesis directly from CO hydrogenation using the dual Cu-Mn-Zn/modified-Y catalysts, it was found that Cu-Mn-Zn/La-Y and Cu-Mn-Zn/Ce-Y were more active than Cu-Mn-Zn/pure-HY. The conversion of CO on Cu-Mn-Zn/Ce-HY achieved 77.1% in an isothermal fixed bed reactor at 245{sup o}C, 2.0 MPa, H{sub 2}/CO = 3/2 and 1500 h{sup -1}. 36 refs., 7 figs., 3 tabs.

  15. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

    Full Text Available Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  16. Co-based alloys design based on first-principles calculations: Influence of transition metal and rare-earth alloying element on stacking fault energy

    Science.gov (United States)

    Achmad, Tria Laksana; Fu, Wenxiang; Chen, Hao; Zhang, Chi; Yang, Zhi-Gang

    2017-01-01

    The main idea of alloy design is to reduce costs and time required by the traditional (trial and error) method, then finding a new way to develop the efficiency of the alloy design is necessary. In this study, we proposed a new approach to the design of Co-based alloys. It is based on the concept that lowering the ratio of stable and unstable stacking fault energy (SFE) could bring a significant increase in the tendency of partial dislocation accumulation and FCC to HCP phase transformation then enhance mechanical properties. Through the advance development of the computing techniques, first-principles density-functional-theory (DFT) calculations are capable of providing highly accurate structural modeling at the atomic scale without any experimental data. The first-principles calculated results show that the addition of some transition metal (Cr, Mo, W, Re, Os, Ir) and rare-earth (Sc, Y, La, Sm) alloying elements would decrease both stable and unstable SFE of pure Co. The dominant deformation mechanism of binary Co-4.5 at.% X (X = alloying element) is extended partial dislocation. Our study reveals Re, W, Mo and La as the most promising alloying additions for the Co-based alloys design with superior performances. Furthermore, the underlying mechanisms for the SFE reduction can be explained regarding the electronic structure.

  17. The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf

    CERN Document Server

    Hirano, Teruyuki; Mann, Andrew W; Sanchis-Ojeda, Roberto; Gaidos, Eric; Narita, Norio; Dai, Fei; Van Eylen, Vincent; Lee, Chien-Hsiu; Onozato, Hiroki; Ryu, Tsuguru; Kusakabe, Nobuhiko; Ito, Ayaka; Kuzuhara, Masayuki; Onitsuka, Masahiro; Tatsuuma, Misako; Nowak, Grzegorz; Pallè, Enric; Ribas, Ignasi; Tamura, Motohide; Yu, Liang

    2015-01-01

    We validate a candidate super-Earth ($R_p=2.38\\pm 0.25R_\\oplus$) on a close-in orbit ($P=2.26$ days) around EPIC 206318379, a metal-rich M4-type dwarf in the Campaign 3 field of the K2 mission. Our follow-up observations included multi-band transit observations from the optical to the near infrared, low-resolution spectroscopy, and high-resolution adaptive-optics (AO) imaging. The phase-folded K2 transit light curve has a V-shape because the transit duration around this small star is comparable to the 30-minute K2 cadence. However, the light curves from our follow-up observations exhibit a sharp ingress and/or egress and flat bottom, ruling out a grazing eclipse of a binary system. We perform a global fit to all ground-based observations using a Gaussian process-based method and show that the transit depths in all passbands ($r'_2, z_\\mathrm{s,2}, J, H, K_\\mathrm{s}$) are within $2.2\\sigma$ of the K2 value. Based on a model of the background stellar population and the absence of nearby sources in our AO imagi...

  18. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  19. Synthesis of main group, rare-earth, and d{sup 0} metal complexes containing beta-hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ka King [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    >F5)3 give the expected dicationic M{HB(C6F5)3}2L (M = Ca, Yb; L = THF2 or TMEDA) and dicationic mono(silylalkyl) LnC(SiHMe2)3{HB(C6F5)3}2 (Ln = Y, Lu, La), respectively. Salt metathesis reactions of Cp2(NR2)ZrX (X = Cl, I, OTf; R = t-Bu, SiHMe2) and lithium hydrosilazide ultimately afford hydride products Cp2(NR2)ZrH that suggest unusual β-hydrogen elimination processes. A likely intermediate in one of these reactions, Cp2Zr[N(SiHMe2)t-Bu][N(SiHMe2)2], is isolated under controlled synthetic conditions. Addition of alkali metal salts to this zirconium hydrosilazide compound produces the corresponding zirconium hydride. However as conditions are varied, a number of other pathways are also accessible, including C-H/Si-H dehydrocoupling, γ-abstraction of a CH, and β-abstraction of a SiH. Our observations suggest that the conversion of (hydrosilazido)zirconocene to zirconium hydride does not follow the classic

  20. Synthesis of main group, rare-earth, and d{sup 0} metal complexes containing beta-hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ka King [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    >F5)3 give the expected dicationic M{HB(C6F5)3}2L (M = Ca, Yb; L = THF2 or TMEDA) and dicationic mono(silylalkyl) LnC(SiHMe2)3{HB(C6F5)3}2 (Ln = Y, Lu, La), respectively. Salt metathesis reactions of Cp2(NR2)ZrX (X = Cl, I, OTf; R = t-Bu, SiHMe2) and lithium hydrosilazide ultimately afford hydride products Cp2(NR2)ZrH that suggest unusual β-hydrogen elimination processes. A likely intermediate in one of these reactions, Cp2Zr[N(SiHMe2)t-Bu][N(SiHMe2)2], is isolated under controlled synthetic conditions. Addition of alkali metal salts to this zirconium hydrosilazide compound produces the corresponding zirconium hydride. However as conditions are varied, a number of other pathways are also accessible, including C-H/Si-H dehydrocoupling, γ-abstraction of a CH, and β-abstraction of a SiH. Our observations suggest that the conversion of (hydrosilazido)zirconocene to zirconium hydride does not follow the classic

  1. Determination of metals and rare earths in leach solution of phosphogypsum by instrumental neutron activation analysis (INAA); Determinacao de metais e terras raras em solucao lixiviada de fosfogesso por AANI

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Gabriela J.L., E-mail: glcosta@ipen.br [Universidade Nove de Julho, Sao Paulo, SP (Brazil); Saueia, Catia H.R.; Mazzilli, Barbara P., E-mail: chsaueia@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The phosphogypsum is a sub-product of the fertilizer industries and is composed of the gypsum matrix (CaSO{sub 4}.2H{sub 2}O) which naturally contains high tenors of impurities such as 2P{sub O}5 and metals coming from the original phosphat rock. The Brazilian phosphogypsum and the various uses has been researched through his elementary and radiochemistry characterization. This work determine the metals (As, Ba, Co and Se) and rare earths (La, Ce, Sm, Eu, Tb and Lu) presents in samples of phosphogypsum leach solutions

  2. 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

  3. Investigating Heavy Metal Pollution in Mining Brownfield and Its Policy Implications: A Case Study of the Bayan Obo Rare Earth Mine, Inner Mongolia, China

    Science.gov (United States)

    Pan, Yuxue; Li, Haitao

    2016-04-01

    The rapid urbanization of China and associated demand for land resources necessitates remediation, redevelopment, and reclamation of contaminated soil. Before these measures are taken, a basic investigation and inventory of heavy metal (HM) pollution levels in contaminated soil is necessary for establishing and implementing the redevelopment plan. In the present study, to identify the policy implications of inventorying and mapping HM pollution of soil in brownfields throughout China, the Bayan Obo giant rare earth element (REE)-Nb-Fe ore deposit of Baotou in Inner Mongolia, China, which is the largest REE mineral deposit in the world, was taken as a case study. Soil samples from 24 sites in Bayan Obo mining area (MA) and 76 sites in mine tailing area (TA) were collected for determining contents of soil HMs (Cr, Cd, Pb, Cu, and Zn). The results showed that the average concentrations of Cr, Cd, Pb, Cu, and Zn in both MA and TA were all higher than their corresponding background values for Inner Mongolia but lower than the Class II criteria of the National Soil Quality Standards of China (GB 15618—1995). Enrichment factor (EF) analysis of the soil samples indicated that the soil in the brownfield sites was highly enriched with Cr, Cd, Pb, Cu, and Zn compared to the corresponding background values. In MA, the EF for Cd was the highest among the studied elements, while in TA, the EF for Cr (3.45) was the highest, closely followed by the EF for Cd (3.34). The potential ecological risk index (RI) indicated a moderate potential ecological risk from the studied HMs in MA and a low potential ecological risk in TA, and the results of RI also suggested that the soil was most heavily polluted by Cd. According to the spatial distribution maps of HM, contamination hot-spots were primarily located near mining-related high-pollution plants. Based on the results, policy recommendations are proposed related to brownfield management in urban planning.

  4. Structural and electronic properties of binary amorphous aluminum alloys with transition metals and rare earth metals; Strukturelle und elektronische Eigenschaften binaerer amorpher Aluminiumlegierungen mit Uebergangsmetallen und Metallen der Seltenen Erden

    Energy Technology Data Exchange (ETDEWEB)

    Stiehler, Martin

    2012-02-03

    The influence of the d-states of the transition metals on the structure formation in amorphous alloys has so far only been inadequately understood. The present work aims to elaborate additional contributions to the understanding of binary amorphous aluminum alloys with transition metals. Special emphasis was placed on alloys with a subgroup of the transition metals, the rare earth metals. Within the scope of the present work, layers of Al-Ce in the region of 15at% Ce-80at% Ce were produced by sequential flash evaporation at 4.2K in the high vacuum, and characterized electronically by electrical resistance and Hall effect measurements as well as structurally by transmission electron diffraction. In addition, studies of plasma resonance were carried out by means of electron energy loss spectroscopy. In the range of 25at% Ce-60at% Ce, homogeneous amorphous samples were obtained. Especially the structural investigations were made difficult by oxidation of the material. The influence of the Ce-4f electrons manifests itself mainly in the low-temperature and magnetoresistance, both of which are dominated by the Kondo effect. The Hall effect in Al-Ce is dominated by anomalous components over the entire temperature range (2K-320K), which are attributed to skew-scattering effects, also due to Ce-4f electrons. Down to 2K there was no macroscopic magnetic order. In the region 2K-20K, the existence of clusters of ordered magnetic moments is concluded. For T> 20K, paramagnetic behavior occurs. With regard to the structural and electronic properties, a-Al-Ce can be classified as a group with a-Al- (Sc, Y, La). In the sense of plasma resonance, a-Al-Ce is excellently arranged in a system known from other Al transition metal alloys. Furthermore, by increasing the results of binary amorphous Al transition metal alloys from the literature, it has been found that the structure formation in these systems is closely linked to a known but still unexplained structure-forming effect that

  5. 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...

  6. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  7. Electron spin resonance study of electron localization and dynamics in metal-molten salt solutions: comparison of M-MX and Ln-LnX sub 3 melts (M alkali metal, Ln = rare earth metal, X = halogen)

    CERN Document Server

    Terakado, O; Freyland, W

    2003-01-01

    We have studied the electron spin resonance (ESR) spectra in liquid K-KCl and M-(NaCl/KCl) sub e sub u sub t mixtures at different concentrations in salt-rich melts approaching the metal-nonmetal transition region. In both systems F-centre-like characteristics are found. Strongly exchange narrowed signals clearly indicate that fast electron exchange occurs on the picosecond timescale. In contrast, the ESR spectra of a (NdCl sub 2)(NdCl sub 3)-(LiCl/KCl) sub e sub u sub t melt are characterized by a large line width of the order of 10 sup 2 mT which decreases with increasing temperature. In this case, the g-factor and correlation time are consistent with the model of intervalence charge transfer, which is supported by recent conductivity and optical measurements. The different transport mechanisms will be discussed.

  8. Bioavailability of heavy metals, germanium and rare earth elements at Davidschacht dump-field in mine affected area of Freiberg (Saxony)

    Science.gov (United States)

    Midula, Pavol; Wiche, Oliver

    2016-04-01

    with the other elements from this group. High amounts of As, Cd, Pb in mould horizons were proved. The surprisingly highest concentrations were determined for As (in average 3328 mg kg-1). The results of the pH measurement indicates acid conditions (in average 4.86, min. 3.89) for whole mine heap. Due to the mobility of Cd and Pb in acid environment, a high mobility of Cd in mobile soil fractions (in average 0.58 mg kg-1) was found, that seems to be responsible for the Cd pollution of Freiberger Mulde river, situated near the dump-field in the East direction from the studied area. The Pb content was in the average 1513 mg kg-1. SE analyses shows, that only the minor amounts of these metals were accounted in fractions I - IV (As: 7.75 %, Pb: 5.48 %, Cd: 26.77 %). The total Ge content in soil samples was 2.7 mg.kg-1in average. The concentrations of Nd and Ce were 17.7 mg kg-1and 38.5 mg kg-1, which is even lower than the average Nd and Ce contents in the Earth crust. However, the concentration of Ge was roughly a factor of two higher, than this average showing a large pool of Ge that could be accessed by phytoextraction. The SE analyses shows, that the average in fractions I - IV is even much lower, than in the case of the above mentioned heavy metals in comparison with Ge (1.75 %), Nd (3.28 %) and Ce (3.12 %). The BCF calculated for plants shows, that the only element, which could be possibly used as the object of phytoaccumulation is Cd (the BCF > 1) in species Populus tremula (3.0, 1.7), Spirea douglasii (1.4, 2.2) and Tanacetum vulgare (3.2, 1.3) at the most sampling places. Since these species represent the natural occurring vegetation of the dump, the use of these species together with soil amendments enhancing the plant availability of elements in soil fractions hold promise for phytoextraction of economically valuable metalloids and consequently an in situ bioremediation of the dump field. This work was realised with the support of Christin Jahns on behalf of the

  9. Biological effects of soaking rapeseeds in light rare earth metals under Cd and Cr stress%轻稀土浸种对油菜镉铬胁迫的生物学效应

    Institute of Scientific and Technical Information of China (English)

    任学军; 任艳军; 杜彬; 马建军

    2011-01-01

    [目的]研究轻稀土抗油菜镉(Cd)铬(Cr)重金属胁迫下的生物学效应,为重金属污染土壤中稀土农用提供理论参考.[方法]采用单一轻稀土(La、Ce、Nd、Pr)浸种处理,通过盆栽试验,研究重金属Cd和Cr胁迫条件下油菜生长发育对Cd、Cr元素吸收累积的影响.[结果]土壤Cd、Cr胁迫未对油菜生长发育产生明显影响,但增加了Cd、Cr含量和累积量,以重金属Cd累积幅度最明显;La、Ce、Nd、Pr浸种处理均抑制土壤中重金属Cd和Cr向油菜茎叶转移与吸收,抑制效果因油菜发育状况、土壤污染程度及稀土元素种类不同而存在差异,随重金属污染程度的加重,其抑制重金属毒害能力增强,以Ce浸种处理效果最佳,同时促进了油菜茎叶中干物质积累.[结论]稀土浸种处理是一种抑制和减少蔬菜重金属吸收和积累的有效途径.%[Objective]The present experiment was conducted to find out the biological effects of soaking rapeseeds in light rare-earth metals (La, Ce, Nd, Pr) on resistance of rapeseed plants to Cd and Cr stress in order to provide a theo-retical reference for agricultural application of rare earth metals in soils polluted with heavy metals. [Method]The growth and development of rapeseed plants and Cd and Cr uptake and accumulation in rape plant was investigated under Cd and Cr stress by soaking rapeseeds in single light rare earth metals, viz., La, Ce, Nd, Pr in pot culture. [Result]The results showed that the Cd and Cr stress in soil had no significant effects on the growth and development of rapeseed plants, rather it increased Cd and Cr content and their accumulation. La, Ce, Nd and Pr seed-soaking treatments inhibited the uptake and translocation of Cd and Cr from soil to stem and leaf of rapeseed plant, and the inhibitory effects differed with respect to growth and development stage, soil pollution extent and rare earth element type. At higher heavy metal pollu-tion , the ability of rape to

  10. {sup 1}H and {sup 23}Na MAS NMR spectroscopy of cationic species in CO{sub 2} selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Arevalo-Hidalgo, Ana G. [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico); Dugar, Sneha; Fu, Riqiang [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Hernandez-Maldonado, Arturo J., E-mail: arturoj.hernandez@upr.edu [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico)

    2012-07-15

    The location of extraframework cations in Sr{sup 2+} and Ba{sup 2+} ion-exchanged SAPO-34 was estimated by means of {sup 1}H and {sup 23}Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO{sub 2} adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO{sub 2} adsorption performance. Highlights: Black-Right-Pointing-Pointer Location of extraframework Sr{sup 2+} or Ba{sup 2+} cations was estimated by means of {sup 1}H and {sup 23}Na MAS NMR. Black-Right-Pointing-Pointer Level of Sr{sup 2+} or Ba{sup 2+} ion exchange was limited by the presence of protons and sodium cations. Black-Right-Pointing-Pointer Presence of ammonium cations in the supercages facilitated the exchange. Black-Right-Pointing-Pointer Sr{sup 2+} and Ba{sup 2+} ion exchanged SAPOs are outstanding CO{sub 2} adsorbents.

  11. Earth-abundant NiS co-catalyst modified metal-free mpg-C3N4/CNT nanocomposites for highly efficient visible-light photocatalytic H2 evolution.

    Science.gov (United States)

    Zhong, Yongming; Yuan, Jielin; Wen, Jiuqing; Li, Xin; Xu, Yuehua; Liu, Wei; Zhang, Shengsen; Fang, Yueping

    2015-11-01

    In the present work, the earth-abundant NiS co-catalyst modified mesoporous graphite-like C3N4 (mpg-C3N4)/CNT nanocomposites were prepared via a two-step strategy: the sol-gel method and the direct precipitation process. The mpg-C3N4/CNT/NiS composite photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy, photoluminescence spectroscopy (PL), photoelectrochemical (PEC) and electrochemical impedance spectra (EIS) experiments. The photocatalytic H2-production activity over the composite catalysts was also evaluated by using an aqueous solution containing triethanolamine under visible light (λ≥ 420 nm). The results showed that the loading of earth-abundant NiS co-catalysts onto metal-free mpg-C3N4/CNT nanocomposites can remarkably enhance their photocatalytic H2-production activity. The optimal loading amount of NiS on metal-free mpg-C3N4/CNT nanocomposites was about 1 wt%. The as-obtained mpg-C3N4/CNT/1% NiS ternary composite photocatalyst exhibits the best H2-evolution activity with the highest rate of about 521 μmol g(-1) h(-1) under visible light (λ≥ 420 nm), which is almost 148 times that of a pure mpg-C3N4/CNT sample. The enhanced photocatalytic activity can be mainly attributed to the synergistic effect of effectively promoted separation of photo-generated electron-hole pairs and enhanced H2-evolution kinetics. The co-loading of nanocarbon materials and earth-abundant co-catalysts onto metal-free mpg-C3N4 photocatalysts offers great potential for practical applications in photocatalytic H2 evolution under visible light illumination.

  12. On the structural and magnetic properties of R{sub 2}Fe{sub 17-x}(A,T){sub x} (R=rare earth; A=Al, Si, Ga; T=transition metal) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rama Rao, K.V.S. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Ehrenberg, H.; Fuess, H. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Markandeyulu, G.; Murthy, V.S. [Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Varadaraju, U.V.; Venkatesan, M. [Indian Inst. of Tech., Madras (India). Materials Science Research Centre; Suresh, K.G. [Indian Inst. of Tech., Bombay (India). Dept. of Physics; Schmidt, P.C. [Technische Univ. Darmstadt (Germany). Inst. fuer Physikalische Chemie

    2002-02-16

    R{sub 2}Fe{sub 17} (R = rare earth) intermetallic compounds constitute one of the most important classes of materials identified as high-energy permanent magnet materials. They crystallize either in the rhombohedral Th{sub 2}Zn{sub 17} structure (for light R) or in the hexagonal Th{sub 2}Ni{sub 17} structure (for heavy R). In this article, we discuss the variations in the lattice parameters (unit cell volume), site occupancies and Curie temperature when non-transition and transition metals are substituted for Fe in R{sub 2}Fe{sub 17} compounds. (orig.)

  13. Rare Earths; The Fraternal Fifteen (Rev.)

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl A. [Iowa State University; Ames Laboratory

    1966-01-01

    Rare earths are a set of 15 elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. They are not rare and not earths; they are metals and quite abundant. They are studied to develop commercial products which are beneficial to mankind, and because some rare earths are important to fission products.

  14. Effect of para-substituents on alkaline earth metal ion extraction by proton di-ionizable calix[4]arene-crown-6 ligands in cone, partial-cone and 1,3-alternate conformations.

    Science.gov (United States)

    Zhou, Hui; Liu, Dazhan; Gega, Jerzy; Surowiec, Kazimierz; Purkiss, David W; Bartsch, Richard A

    2007-01-21

    Two carboxylic acid or N-(X)sulfonyl carboxamide groups were incorporated into calix[4]arene-crown-6 compounds to afford di-ionizable ligands for use in divalent metal ion separations. Acidities of the N-(X)sulfonyl carboxamide groups were tuned by variation of the electron-withdrawing properties of X. Cone, partial-cone and 1,3-alternate conformations were obtained by different synthetic strategies and their structures verified by NMR spectroscopy. Competitive solvent extractions of alkaline earth metal cations from aqueous solutions into chloroform were performed and the results compared with those reported previously for di-ionizable p-tert-butylcalix[4]arene-crown-6 analogues to probe the influence of the para-substituent on the calix[4]arene scaffold on extraction selectivity and efficiency.

  15. Achievements in the Project-"The Adsorption of Rare Earth Metal Ions and Ligands on Steel, Aluminum and its Synergistic Mechanism"

    Institute of Scientific and Technical Information of China (English)

    Li Xianghong; Qu Qing; Jiang Shu'an; Zhou Jun

    2006-01-01

    @@ 1. Background Corrosion is a fundamental process that plays an important role in economics and safety, particularly for metals and alloys. Nowadays, corrosion problems have received a considerable amount of attentions. The annual direct cost of metallic corrosion ranges from 2% to 4% of national GDP in industrialized countries, and this cost sounds escalating in the future.

  16. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  17. First-principles study of fission product (Xe, Cs, Sr) incorporation and segregation in alkaline earth metal oxides, HfO2, and MgO-HfO2 interface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang-yang [Los Alamos National Laboratory; Uberuaga, Blas P [Los Alamos National Laboratory; Sickafus, Kurt E [Los Alamos National Laboratory

    2008-01-01

    In order to close the nuclear fuel cycle, advanced concepts for separating out fission products are necessary. One approach is to use a dispersion fuel form in which a fissile core is surrounded by an inert matrix that captures and immobilizes the fission products from the core. If this inert matrix can be easily separated from the fuel, via e.g. solution chemistry, the fission products can be separated from the fissile material. We examine a surrogate dispersion fuel composition, in which hafnia (HfO{sub 2}) is a surrogate for the fissile core and alkaline earth metal oxides are used as the inert matrix. The questions of fission product incorporation in these oxides and possible segregation behavior at interfaces are considered. Density functional theory based calculations for fission product elements (Xe, Sr, and Cs) in these oxides are carried out. We find smaller incorporation energy in hafnia than in MgO for Cs and Sr, and Xe if variation of charge state is allowed. We also find that this trend is reversed or reduced for alkaline earth metal oxides with large cation sizes. Model interfacial calculations show a strong tendency of segregation from bulk MgO to MgO-HfO{sub 2} interfaces.

  18. Transition metal (Cr{sup 3+}) and rare earth (Eu{sup 3+}, Dy{sup 3+}) ions used as a spectroscopic probe in compositional-dependent lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, W.A., E-mail: Wojciech.Pisarski@us.edu.p [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Pisarska, J. [Silesian University of Technology, Department of Materials Science, Krasinskiego 8, 40-019 Katowice (Poland); Dominiak-Dzik, G.; Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 Wroclaw (Poland)

    2009-09-18

    Compositional-dependent lead borate glasses doped with transition metal and rare earth ions were studied using absorption and luminescence spectroscopy. The trivalent Cr{sup 3+}, Eu{sup 3+} and Dy{sup 3+} ions were used as a spectroscopic probe in glass samples with various PbO/B{sub 2}O{sub 3} ratios. Spectral analysis indicates that Cr{sup 3+} ions occupy intermediate field sites; the both sites coexist and emit from the {sup 4}T{sub 2} (low-field) and the {sup 2}E (high-field) states, respectively. The R and Y/B values due to {sup 5}D{sub 0}-{sup 7}F{sub 2}/{sup 5}D{sub 0}-{sup 7}F{sub 1} and {sup 4}F{sub 9/2}-{sup 6}H{sub 15/2}/{sup 4}F{sub 9/2}-{sup 6}H{sub 13/2} luminescence intensity ratios of Eu{sup 3+} and Dy{sup 3+} ions, respectively, increase with increasing heavy metal (PbO) content, suggesting higher asymmetry and more covalent bonding character between rare earth and oxygen ions.

  19. Vapor-liquid partitioning of alkaline earth and transition metals in NaCl-dominated hydrothermal fluids: An experimental study from 360 to 465 °C, near-critical to halite saturated conditions

    Science.gov (United States)

    Pester, Nicholas J.; Ding, Kang; Seyfried, William E.

    2015-11-01

    Multi-phase fluid flow is a common occurrence in magmatic hydrothermal systems; and extensive modeling efforts using currently established P-V-T-x properties of the NaCl-H2O system are impending. We have therefore performed hydrothermal flow experiments (360-465 °C) to observe vapor-liquid partitioning of alkaline earth and first row transition metals in NaCl-dominated source solutions. The data allow extraction of partition coefficients related to the intrinsic changes in both chlorinity and density along the two-phase solvus. The coefficients yield an overall decrease in vapor affinity in the order Cu(I) > Na > Fe(II) > Zn > Ni(II) ⩾ Mg ⩾ Mn(II) > Co(II) > Ca > Sr > Ba, distinguished with 95% confidence for vapor densities greater than ∼0.2 g/cm3. The alkaline earth metals are limited to purely electrostatic interactions with Cl ligands, resulting in an excellent linear correlation (R2 > 0.99) between their partition coefficients and respective ionic radii. Though broadly consistent with this relationship, relative behavior of the transition metals is not well resolved, being likely obscured by complex bonding processes and the potential participation of Na in the formation of tetra-chloro species. At lower densities (at/near halite saturation) partitioning behavior of all metals becomes highly non-linear, where M/Cl ratios in the vapor begin to increase despite continued decreases in chlorinity and density. We refer to this phenomenon as "volatility", which is broadly associated with substantial increases in the HCl/NaCl ratio (eventually to >1) due to hydrolysis of NaCl. Some transition metals (e.g., Fe, Zn) exhibit volatility prior to halite stability, suggesting a potential shift in vapor speciation relative to nearer critical regions of the vapor-liquid solvus. The chemistry of deep-sea hydrothermal fluids appears affected by this process during magmatic events, however, our results do not support suggestions of subseafloor halite precipitation

  20. Binding to Redox-Inactive Alkali and Alkaline Earth Metal Ions Strongly Deactivates the C-H Bonds of Tertiary Amides toward Hydrogen Atom Transfer to Reactive Oxygen Centered Radicals.

    Science.gov (United States)

    Salamone, Michela; Carboni, Giulia; Mangiacapra, Livia; Bietti, Massimo

    2015-09-18

    The effect of alkali and alkaline earth metal ions on the reactions of the cumyloxyl radical (CumO(•)) with N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) was studied by laser flash photolysis. In acetonitrile, a >2 order of magnitude decrease in the rate constant for hydrogen atom transfer (HAT) from the C-H bonds of these substrates (kH) was measured after addition of Li(+). This behavior was explained in terms of a strong interaction between Li(+) and the oxygen atom of both DMF and DMA that increases the extent of positive charge on the amide, leading to C-H bond deactivation toward HAT to the electrophilic radical CumO(•). Similar effects were observed after addition of Ca(2+), which was shown to strongly bind up to four equivalents of the amide substrates. With Mg(2+), weak C-H deactivation was observed for the first two substrate equivalents followed by stronger deactivation for two additional equivalents. No C-H deactivation was observed in DMSO after addition of Li(+) and Mg(2+). These results point toward the important role played by metal ion Lewis acidity and solvent Lewis basicity, indicating that C-H deactivation can be modulated by varying the nature of the metal cation and solvent and allowing for careful control over the HAT reactivity of amide substrates.

  1. Correlation-induced metal-insulator transitions in d{sup 0} magnetic superlattices based on alkaline-earth monoxides: Insights from ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yi-Lin [Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Dong, Shengjie [Department of Physics, Tianjin Normal University, Tianjin 300387 (China); Zhou, Baozeng [Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Zhao, Hui [Department of Physics, Tianjin Normal University, Tianjin 300387 (China); Wu, Ping, E-mail: pingwu@tju.edu.cn [Department of Applied Physics, Institute of Advanced Materials Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China)

    2015-06-15

    Using first-principles density functional theory calculations, we have investigated the electronic structure and magnetic properties of four superlattices (MO){sub 1}/(MX){sub 1} (001) (M=Ca and Sr; X=N and C). Our results show that compared with standard GGA approach, the GGA plus effective U{sub eff} scheme can correct electronic structure and magnetic properties in some extent. With enhancing electronic correlation, for (CaO){sub 1}/(CaN){sub 1}, (SrO){sub 1}/(SrN){sub 1}, and (SrO){sub 1}/(SrC){sub 1}, the bands across Fermi level are divided into two parts and the shape of isotropic spherical spin atmosphere becomes anisotropic dumbbell-like with specific orientation, accompanying metal-insulator transitions. For (CaO){sub 1}/(CaC){sub 1}, the states just smearing with the Fermi level shift to lower energy region below Fermi level, indicating the transformation from a nearly half metal to an actual half metal occurs. The different behavior of (CaO){sub 1}/(CaC){sub 1} compared with three other compounds may be caused by the larger ionization energy of calcium than that of strontium and the smaller electronegativity of carbon than that of nitrogen. - Highlights: • The magnetic behaviors of four d{sup 0} superlattices are investigated. • The enhanced electronic correlation influences the magnetic properties. • (CaO){sub 1}/(CaC){sub 1} transforms from a nearly half metal to an actual half metal. • The other three compounds transform from half metals to magnetic insulators.

  2. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  3. Helium in Earth's early core

    Science.gov (United States)

    Bouhifd, M. A.; Jephcoat, Andrew P.; Heber, Veronika S.; Kelley, Simon P.

    2013-11-01

    The observed escape of the primordial helium isotope, 3He, from the Earth's interior indicates that primordial helium survived the energetic process of planetary accretion and has been trapped within the Earth to the present day. Two distinct reservoirs in the Earth's interior have been invoked to account for variations in the 3He/4He ratio observed at the surface in ocean basalts: a conventional depleted mantle source and a deep, still enigmatic, source that must have been isolated from processing throughout Earth history. The Earth's iron-based core has not been considered a potential helium source because partitioning of helium into metal liquid has been assumed to be negligible. Here we determine helium partitioning in experiments between molten silicates and iron-rich metal liquids at conditions up to 16GPa and 3,000K. Analyses of the samples by ultraviolet laser ablation mass spectrometry yield metal-silicate helium partition coefficients that range between 4.7×10-3 and 1.7×10-2 and suggest that significant quantities of helium may reside in the core. Based on estimated concentrations of primordial helium, we conclude that the early core could have incorporated enough helium to supply deep-rooted plumes enriched in 3He throughout the age of the Earth.

  4. High-Tc Superconductivity and Raman Scattering Study of the phonon properties of electron doped (transition metal, rare-earth) - Oxygen-Free CaFeAsF and compared with RFeAsO system

    Science.gov (United States)

    Sasmal, Kalyan; Hadjiev, Viktor; Chu, C. W.(Paul)

    Quaternary CaFeAsF has ZrCuSiAs-type structure,(RO)δ+ layer in RFeAsO replaced by (CaF)δ+ layer,with tetragonal (P4/nmm)-orthorhombic (Cmma) phase transition at 134K,while magnetic order,SDW sets in at 114K. Partial replacement of Fe with Co/Ni is direct electron doping to (FeAs)δ+ layer.Tc ~15K in CaFe0.9Ni0.1AsF.Substitution of rare earth metal for alkaline earth metal suppresses anomaly in resistivity & induces superconductivity.Tc ~52K in Ca0.5Pr0.5FeAsF.Characterized by resistivity, susceptibility,XRD & EDX-SEM.Upper critical field estimated from magneto resistance.Bulk superconductivity proved by DC magnetization. Hall coefficient RH revealed hole-like charge carriers in parent compound CaFeAsF, while electron-type (RH in normal state is -Ve) for Ca0.5Pr0.5FeAsF.Evolution of Raman active phonons of Ca1-xPrxFeAsF measured with polarized Raman spectroscopy at room temperature from absurfaces of impurity-free microcrystals.Spectra exhibit sharp phonon lines on very weak electronic scattering background.Frequency and symmetry of Raman phonons involving out-of-plane atomic vibrations are found at 162.5 cm-1 (A1 g, Pr), 201 cm-1 (A1 g, As), 215.5 cm-1 (B1 g, Fe), 265 cm-1 (Eg, Fe) and 334 cm-1 (B1 g, F) for Ca0.5Pr0.5FeAsF.Observations are compared with RFeAsO unconventional superconductors also possibly related to magnetic fluctuations

  5. Magnetic and transport properties of R(Mn, In)2 (R—rare-earth metals) with AlB2-structure type

    Science.gov (United States)

    Dzevenko, M.; Havela, L.; Prokleška, J.; Svoboda, P.; Miliyanchuk, K.; Kalychak, Y.

    2007-04-01

    We studied the crystal structure and magnetic properties of ternary rare-earth R(Mn,In) 2 compounds (R=Y, La, Ce, Tb-Tm, Lu), which crystallize in the AlB 2-structure type with approximate stoichiometry RMn 0.67In 1.33, but adopting a variable Mn deficiency. YMn 0.92In 1.08 orders antiferromagnetically below TN ≈ 247 K, CeMn 0.65In 1.35 is ferromagnetic with TC=134 K. The compounds with magnetic rare earths tend to a glassy magnetic state, presumably due to the disorder in the Mn/In sublattice together with competing exchange interactions. The disorder has also a dramatic impact on the temperature dependence of the electrical resistivity, which is rather flat due to a strong scattering. The absence of long-range order was proved also by specific-heat measurements. Hydrogen absorption, tested for several compounds, led to the synthesis of LaMn 0.49In 1.51H 0.75(5).

  6. Binary phase diagrams of the rare earth metals with zinc: the Tb-Zn, Ho-Zn and Er-Zn systems

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, A.; Cardinale, A.M.; Delfino, S.; Ferro, R. [Dipt. di Chimica e Chimica Industriale, Sezione di Chimica Inorganica e Metallurgia, Univ. di Genova, (Italy)

    2005-12-01

    The phase diagram of the Er-Zn system has been experimentally investigated over its whole composition range by using differential thermal analysis, X-ray diffraction, optical and scanning electron microscopy, and electron probe microanalysis. Seven intermetallic phases have been found and their crystal structure confirmed, namely ErZn, ErZn{sub 2}, ErZn{sub 3}, Er{sub 13}Zn{sub 58}, ErZn{sub 5}, Er{sub 2}Zn{sub 17}, and ErZn{sub 12}. Four eutectic reactions occur. A degenerate invariant effect has been found in the Zn-rich region. The results obtained in this investigation have been used, together with those of other previously studied rare earth-Zn systems, to predict the constitutional properties of the Tb-Zn and Ho-Zn systems, taking into account that the alloying behaviour of the different rare earths with the same element varies according to systematic patterns. The predicted phase diagrams of the Tb-Zn and Ho-Zn systems are compared with selected equilibria experimentally determined by analysing a few key compositions. (orig.)

  7. Ultrafast photoinduced dynamics of the organolead trihalide perovskite CH3NH3PbI3 on mesoporous TiO2 scaffolds in the 320-920 nm range.

    Science.gov (United States)

    Flender, Oliver; Klein, Johannes R; Lenzer, Thomas; Oum, Kawon

    2015-07-15

    We present femtosecond broadband transient absorption experiments for the investigation of the carrier dynamics in the organolead trihalide perovskite CH3NH3PbI3. The perovskite was prepared on a mesoporous TiO2 scaffold either by 1-step deposition from solution or by 2-step methods employing deposition of lead iodide followed by an on-surface reaction with methylammonium iodide. The thin films were characterized by XRD and FTIR chemical mapping. After pumping with an ultrashort laser pulse at 400 or 500 nm, the dynamics were monitored by a broadband supercontinuum reaching from the near IR (920 nm) into the UV. Specifically, the usage of quartz substrates and thin perovskite/TiO2 films enabled us to cover the spectral development down to 320 nm. The charge carrier dynamics were largely independent from the specific route of perovskite preparation: initial ultrafast carrier relaxation steps with time constants τCC and τCOP of 1000 ps) and Auger recombination (τAR = 9, 75 and 450 ps). Carrier relaxation was accompanied by formation of an absorption band around 550 nm, with a characteristic structure assignable to a transient Stark effect, i.e. a red-shift of the perovskite spectrum due to the appearance of a directed electric field in the material and possibly additional influence of lattice heating. We observed a substantial Stokes shift between the relaxed photobleach and photoluminescence bands. Contributions of unreacted PbI2 to the transient absorption features appear to be negligible.

  8. 稀土-过渡金属薄膜磁各向异性的理论研究%Theoretic studies on the magnetic anisotropy of rare-earth transition-metal thin films

    Institute of Scientific and Technical Information of China (English)

    何一鸣; 钱显毅; 黄致新

    2011-01-01

    The magnetic anisotropy of rare-earth transition-metal thin films is investigated in this paper. Based on the reference review and the analysis of thin film forming process by sputtering, the single ion model has been put foreword. With concrete computation, we found that when the composition of the film is R31Co69 and the rare-earth element is Tb, the magnetic anisotropy value can be as high as 3. 1×106 erg/cm3. And the Coulomb interactions between the non-S state rare-earth ion in non-spherical electric charge distribution with the deformed local crystalline field accounts for the major source of high perpendicular anisotropy of TbCo amorphous films.%对稀土-过渡金属薄膜的磁各向异性进行了理论分析研究.通过分析其它模型以及薄膜成膜过程的特点,建立了单离子模型,并进行了理论分析和计算.结果发现:组分为R31Co69薄膜中稀土元素R为Tb时的Ku值最大,接近3.1×106 erg/cm3.对于TbCo非晶垂直磁化膜而言,具有非球对称电荷分布的非S态离子Tb与局部电场的相互作用构成了其垂直磁各向异性的主要部分.

  9. Catalysis using hydrous metal oxide ion exchanges

    Science.gov (United States)

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  10. Catalysis using hydrous metal oxide ion exchangers

    Science.gov (United States)

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  11. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  12. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  13. Ab Initio Study of Chemical Reactions of Cold SrF and CaF Molecules with Alkali-Metal and Alkaline-Earth-Metal Atoms: The Implications for Sympathetic Cooling.

    Science.gov (United States)

    Kosicki, Maciej Bartosz; Kędziera, Dariusz; Żuchowski, Piotr Szymon

    2017-06-01

    We investigate the energetics of the atom exchange reaction in the SrF + alkali-metal atom and CaF + alkali-metal atom systems. Such reactions are possible only for collisions of SrF and CaF with the lithium atoms, while they are energetically forbidden for other alkali-metal atoms. Specifically, we focus on SrF interacting with Li, Rb, and Sr atoms and use ab initio methods to demonstrate that the SrF + Li and SrF + Sr reactions are barrierless. We present potential energy surfaces for the interaction of the SrF molecule with the Li, Rb, and Sr atoms in their energetically lowest-lying electronic spin states. The obtained potential energy surfaces are deep and exhibit profound interaction anisotropies. We predict that the collisions of SrF molecules in the rotational or Zeeman excited states most likely have a strong inelastic character. We discuss the prospects for the sympathetic cooling of SrF and CaF molecules using ultracold alkali-metal atoms.

  14. Molten salt phase diagram evaluation by pattern recognition:Part Ⅰ Divalent rare earth halide and alkali metal halide binary systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    At present CALPHAD (CALculation of PHAse Diagram) technique is not capable of predicting whether there exists intermediate compound, much less predicting the formulae, the number, and the melting congruence of intermediate compounds. To solve this problem, a new approach called the phase diagram evaluation by pattern recognition (PDEPR) was improved. The micro-parameters, such as the radius and the electronegativity of the element, were used as original features and then they were transformed and spanned to the different features in multi-dimensional space.Then a set of classifying functions were obtained to predict the information of intermediate compounds in REX2-AX systems (RE-rare earth element; A-Li, Na, K, Rb, and Cs; X F, Cl, Br, and 1). It is comparatively important for the design of materials.

  15. A review of the literature on the toxicity of rare-earth metals as it pertains to the Engineering Demonstration System surrogate testing

    Energy Technology Data Exchange (ETDEWEB)

    Wald, P.H.

    1989-10-01

    A review of data on animal and damaging human exposure to the rare-earth elements has been made. Incidental oral ingestion is considered to be harmless and accidental nonrespiratory uptake does not represent a health risk. Equipment design and operating procedures mitigate against dermatologic or ophthalmologic risk to workers and the public. Animal and human inhalation studies confirm the use of the Threshold Limit Value-Time Weighted Average (TLV-TWA) for yttrium as a conservative measure for evaluation of the Engineering Demonstration System (EDS) emission of the lanthanons. This value (1 mg/m{sup 3}) is also consistent with the OSHA-established permissible exposure limit (PEL). Environmental exposures that are maintained at a level below the TLV/PEL value should result in no health impact to workers, visitors, or the public. 38 refs., 7 tabs.

  16. High-precision analysis on annual variations of heavy metals, lead isotopes and rare earth elements in mangrove tree rings by inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Yu Kefu [South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xin-Gang Road, Guangzhou 510301 (China) and Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis (CMM), University of Queensland, Qld 4072 (Australia)]. E-mail: kefuyu@scsio.ac.cn; Kamber, Balz S. [Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis (CMM), University of Queensland, Qld 4072 (Australia); Department of Earth Sciences, Laurentian University, Sudbury, ONP3E2C6 (Canada); Lawrence, Michael G. [Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis (CMM), University of Queensland, Qld 4072 (Australia); Greig, Alan [Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis (CMM), University of Queensland, Qld 4072 (Australia); School of Earth Sciences, University of Melbourne, Vic. 3010 (Australia); Zhao Jianxin [Radiogenic Isotope Laboratory, Centre for Microscopy and Microanalysis (CMM), University of Queensland, Qld 4072 (Australia)

    2007-02-15

    Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes ({sup 207}Pb/{sup 206}Pb and {sup 208}Pb/{sup 206}Pb) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change.

  17. High-precision analysis on annual variations of heavy metals, lead isotopes and rare earth elements in mangrove tree rings by inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Yu, Ke-Fu; Kamber, Balz S.; Lawrence, Michael G.; Greig, Alan; Zhao, Jian-Xin

    2007-02-01

    Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes ( 207Pb/ 206Pb and 208Pb/ 206Pb) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change.

  18. Element Substitution Effect in Transition M et al Oxypnictide Re(O1-xFx)TAs (Re=rare earth, T=transition metal)

    Institute of Scientific and Technical Information of China (English)

    CHEN Gen-Fu; LI Zheng; WU Dan; DONG Jing; LI Gang; HU Wan-Zheng; ZHENG Ping; LUO Jian-Lin; WANG Nan-Lin

    2008-01-01

    Different element substitution effects in transition metal oxypnictide Re(O1-xFx)TAs, with Re=La, Ce, Nd, Eu, Gd, Tin, T=Fe, Ni, Ru, are studied. Similar to the La- or Ce-based systems, we find that the pure NdOFeAs shows a strong resistivity anomaly near 145 K, which is ascribed to the spin-density-wave instability. Electron doping by F increases Tc to about 50K. While in the case of Gd, Tc is reduced below 10K. The tetragonal ZrCuSiAs-type structure couM not be formed for Eu or Tm substitution in our preparing process. For the Ni-based case, although both pure and F-doped LaONiAs are superconducting, no superconductivity is found when La is replaced by Ce in both the cases, instead a ferromagnetic ordering transition is likely to form at low temperature in the undoped sample. We also synthesize LaO1-xFxRuAs and CeO1-xFx RuAs compounds. The metallic behaviour is observed down to 4 K.

  19. Japanese Rare Earth Market

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Since China cancelled export rebate in May this year,prices of magnetic materials related rare earth productscontinuously rose. Increasing production cost is largelyattributed to investment in environmental protectionequipments. Prices of Nd and Dy metals rose 20~30% over thebeginning of this year.Price of Nd was USD 11.5 - 12/Kg from USD 9/Kg at theend of 2004, up 30%. Price of Dy rose to USD 65- 70/Kg fromUSD 50/Kg early this year, up 20%. Price of Pr climbed to USD13.5 - 14/Kg from USD 11/Kg, up 30%. Pri...

  20. Homoleptic rare earth dipyridylamides [Ln2(N(NC5H4)2)6], Ln = Ce, Nd, Sm, Ho, Er, Tm, Yb, and Sc: metal oxidation by the amine melt and in 1,2,3,4-tetrahydroquinoline with the focus of different metal activation by amalgams, liquid ammonia, and microwaves.

    Science.gov (United States)

    Müller-Buschbaum, Klaus; Quitmann, Catharina C

    2006-03-20

    Homoleptic dimeric dipyridylamide complexes of the rare earth elements are obtained by solvent-free oxidation reactions of the metals with melts of 2,2'-dipyridylamine. As the thermal stabilities of the ligand as well as the amide complexes are limiting factors in these high-temperature syntheses, several different metal activation procedures have been investigated: the formation of Ln amalgams and dissolution of the metals in liquid ammonia as well as coupling to microwaves. For comparison with a solvent that shows low solubility of the metals and products, reactions in 1,2,3,4-tetrahydroquinoline were also carried out. For all lanthanides and group 3 metals used homoleptic dimers of the formula [Ln(2)(Dpa)(6)], Ln = Ce (1), Nd (2), Sm (3), Ho (4), Er (5), Tm (6), Yb (7), and Sc (8) and Dpa- = (C5H4N)2N-, were obtained, all containing trivalent rare earth ions with a distorted square antiprismatic nitrogen coordination. Due to the large differences in the ionic radii of the metal ions, two different structure types are found that crystallize in the space groups P2(1)/c and P2(1)/n with the border of the two types being between Tm and Yb. The orientations of two 1,3/1,3-double chelating and linking dipyridylamide ligands (Dpa(-) = (C(5)H(4)N)(2)N(-)) result in different overall orientations of the dimers and thus two structure types. All compounds were identified by single-crystal X-ray analysis. Mid-IR, far IR, and Raman spectroscopy, microanalyses, and simultaneous DTA/TG as well as mass spectrometry regarding their thermal behavior were also carried out to characterize the products. Crystal data for the two types follow. Ce (1): P2(1)/n; T = 170(2) K; a = 1063.0(1), b = 1536.0(1), c = 1652.0(2) pm; beta = 101.60(1) degrees ; V = 2642.2(3) x 10(6) pm(3); R(1) for F(o) > 4sigma(F(o)) = 0.046, wR(2) = 0.120. Sc (8): P2(1)/c; T = 170(2) K; a = 1073.0(1), b = 1506.2(2), c = 1619.8(2) pm; beta = 103.16(9) degrees ; V = 2548.9(5) x 10(6) pm(3); R(1) for F(o) > 4sigma

  1. All-Metal Tires

    Science.gov (United States)

    Bickler, Donald B.; Sword, Lee F.; Lindemann, Randel A.

    1994-01-01

    Tires used where elastomeric and pneumatic tires would not function. Metal tires withstand extreme temperatures. Used on Earth for vehicles and robots that fight fires or clean up dangerous chemicals.

  2. A study on equilibrium and kinetics of ion exchange of alkaline earth metals using an inorganic cation exchanger - zirconium titanium phosphate

    Indian Academy of Sciences (India)

    Amin Jignasa; Thakkar Rakesh; Chudasama Uma

    2006-03-01

    An advanced inorganic cation exchange material of the class of tetravalent metal acid (TMA) salt, zirconium titanium phosphate (ZTP), has been synthesized by a modified sol-gel technique. ZTP has been characterized by elemental analysis (ICP-AES), thermal analysis (TGA), FTIR and X-ray diffraction studies. The Nernst-Planck equation has been used to study the forward and reverse ion exchange kinetics of Mg (II), Ca (II), Sr (II) and Ba (II) with H (I) at four different temperatures. The mechanism of exchange is particle diffusion, as confirmed by the linear (dimensionless time parameter) vs (time) plots. The exchange process is thus controlled by the diffusion within the exchanger particles for the systems studied herein. Further, various kinetic parameters like self-diffusion coefficient (0), energy of activation () and entropy of activation (*) have been evaluated under conditions favouring a particle diffusion-controlled mechanism.

  3. The Ternary Alkaline-Earth Metal Manganese Bismuthides Sr2MnBi2 and Ba2Mn1-xBi2 (x ≈ 0.15).

    Science.gov (United States)

    Ovchinnikov, Alexander; Saparov, Bayrammurad; Xia, Sheng-Qing; Bobev, Svilen

    2017-10-02

    Two new ternary manganese bismuthides have been synthesized and their structures established based on single-crystal X-ray diffraction methods. Sr2MnBi2 crystallizes in the orthorhombic space group Pnma (a = 16.200(9) Å, b = 14.767(8) Å, c = 8.438(5) Å, V = 2018(2) Å(3); Z = 12; Pearson index oP60) and is isostructural to the antimonide Sr2MnSb2. The crystal structure contains corrugated layers of corner- and edge-shared [MnBi4] tetrahedra and Sr atoms enclosed between these layers. Electronic structure calculations suggest that Sr2MnBi2 is a magnetic semiconductor possessing Mn(2+) (high-spin d(5)) ions, and its structure can be rationalized within the Zintl concept as [Sr(2+)]2[Mn(2+)][Bi(3-)]2. The temperature dependence of the resistivity shows behavior consistent with a degenerate semiconductor/poor metal, and magnetic susceptibility measurements reveal a high degree of frustration resulting from the two-dimensional nature of the structure. The compositionally similar Ba2Mn1-xBi2 (x ≈ 0.15) crystallizes in a very different structure (space group Imma, a = 25.597(8) Å, b = 25.667(4) Å, c = 17.128(3) Å, V = 11253(4) Å(3); Z = 64; Pearson index oI316) with its own structure type. The complex structure boasts Mn atoms in a variety of coordination environments and can be viewed as consisting of two interpenetrating 3D frameworks, linked by Bi-Bi bonds. Ba2Mn1-xBi2 can be regarded as a highly reduced compound with anticipated metallic behavior.

  4. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation.

    Science.gov (United States)

    Minenkov, Yury; Bistoni, Giovanni; Riplinger, Christoph; Auer, Alexander A; Neese, Frank; Cavallo, Luigi

    2017-04-05

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol(-1) if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol(-1), indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  5. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  6. Trace Metals, Rare Earths, Carbon and Pb Isotopes as Proxies of Environmental Catastrophe at the Permian - Triassic Boundary in Spiti Himalayas, India

    Science.gov (United States)

    Ghosh, N.; Basu, A. R.; Garzione, C. N.; Ghatak, A.; Bhargava, O. N.; Shukla, U. K.; Ahluwalia, A. D.

    2015-12-01

    Himalayan sediments from Spiti Valley, India preserve geochemical signatures of the Permian - Triassic (P-Tr) mass extinction in the Neo-Tethys Ocean. We integrate new sedimentological and fossil record with high-resolution geochemical-isotopic data from Spiti that reveals an ecological catastrophe of global proportions. Trace elements of U, Th, Nb, Ta, Zr, Hf, the rare earths (REE) and carbon, oxygen and lead isotopes measured across the P-Tr boundary in Spiti are used as proxies for evaluating abrupt changes in this continental shelf environment. δ13Corg excursions of 2.4‰ and 3.1‰ in Atargu and Guling P-Tr sections in Spiti Valley are associated with an abrupt fall of biological productivity while δ13Ccarb and δ18Ocarb record of these sediments shows effects of diagenesis. Here, the P-Tr boundary is compositionally distinct from the underlying Late Permian gray shales, as a partly gypsiferous ferruginous layer that allows additional geochemical-isotopic investigation of sedimentary sources. Conspicuous Ce - Eu anomalies in the light REE-enriched Late Permian shales reflect the source composition of the adjacent Panjal Trap basalts of Kashmir. An abrupt change of this source to continental crust is revealed by Nb - Ta and Zr - Hf anomalies at the P-Tr ferruginous layer and continuing through the overlying Early Triassic carbonate rocks. Pb concentration and isotope ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb identify changes in the sedimentary element flux, distinguishing the Late Permian shales from the distinct siliciclastic continental crustal signature in the Early Triassic carbonates. These geochemical-isotopic constraints on the sedimentary geochemistry of one of the most critical transitions in geological record establish the utility of multi-proxy datasets for paleoenvironmental reconstructions.

  7. Processing of rare earth concentrates

    Institute of Scientific and Technical Information of China (English)

    Pamela Alex; R. C. Hubli; A.K. Suri

    2005-01-01

    The paper describes process details for extraction of rare earths from an intermediate grade concentrate of Madhya Pradesh region in India and a South African slag. The xenotime concentrate obtained from the former place was an intermediate grade (47%) rare earth phosphate containing both monazite and xenotime. The South African slag was a low-grade waste product typically containing only 4% of rare earths. The rare earth resource concentrates have been treated individually by different methods such as alkali fusion and alkali leaching to convert them into their mixed oxides. Both types of materials have been processed and greater than 98% solubilization of metal values has been achieved in the intermediate grade xenotime and 80% from the South African slag. The residue of xenotime hydroxide has been washed thoroughly to collect the sodium phosphate, as by-product and the slurry pH have been adjusted to separate rare earths from thorium effectively. Other impurities such as uranium and iron have been removed by precipitation of rare earths by oxalic acid. It has been possible to recover >95% yttrium along with other rare earth oxides.

  8. The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf

    Science.gov (United States)

    Hirano, Teruyuki; Fukui, Akihiko; Mann, Andrew W.; Sanchis-Ojeda, Roberto; Gaidos, Eric; Narita, Norio; Dai, Fei; Van Eylen, Vincent; Lee, Chien-Hsiu; Onozato, Hiroki; Ryu, Tsuguru; Kusakabe, Nobuhiko; Ito, Ayaka; Kuzuhara, Masayuki; Onitsuka, Masahiro; Tatsuuma, Misako; Nowak, Grzegorz; Pallè, Enric; Ribas, Ignasi; Tamura, Motohide; Yu, Liang

    2016-03-01

    We validate a {R}p=2.32+/- 0.24{R}\\oplus planet on a close-in orbit (P = 2.260455 ± 0.000041 days) around K2-28 (EPIC 206318379), a metal-rich M4-type dwarf in the Campaign 3 field of the K2 mission. Our follow-up observations included multi-band transit observations from the optical to the near-infrared, low-resolution spectroscopy, and high-resolution adaptive optics (AO) imaging. We perform a global fit to all of the observed transits using a Gaussian process-based method and show that the transit depths in all of the passbands adopted for the ground-based transit follow-ups ({r}2\\prime ,{z}s,2,J,H,{K}s) are within ˜2σ of the K2 value. Based on a model of the background stellar population and the absence of nearby sources in our AO imaging, we estimate the probability that a background eclipsing binary could cause a false positive to be GJ 1214b. Given the relative brightness of K2-28 in the near-infrared ({m}{Kep}=14.85 mag and mH = 11.03 mag) and relatively deep transit (0.6%-0.7%), a comparison between the atmospheric properties of these two planets with future observations would be especially interesting.

  9. 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.

  10. 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.

  11. Physical and electrical characteristics of AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors with rare earth Er{sub 2}O{sub 3} as a gate dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ray-Ming, E-mail: rmlin@mail.cgu.edu.tw; Chu, Fu-Chuan; Das, Atanu; Liao, Sheng-Yu; Chou, Shu-Tsun; Chang, Liann-Be

    2013-10-01

    In this study, the rare earth erbium oxide (Er{sub 2}O{sub 3}) was deposited using an electron beam onto an AlGaN/GaN heterostructure to fabricate metal-oxide-semiconductor high-electron-mobility transistors (MOS–HEMTs) that exhibited device performance superior to that of a conventional HEMT. Under similar bias conditions, the gate leakage currents of these MOS–HEMT devices were four orders of magnitude lower than those of conventional Schottky gate HEMTs. The measured sub-threshold swing (SS) and the effective trap state density (N{sub t}) of the MOS–HEMT were 125 mV/decade and 4.3 × 10{sup 12} cm{sup −2}, respectively. The dielectric constant of the Er{sub 2}O{sub 3} layer in this study was 14, as determined through capacitance–voltage measurements. In addition, the gate–source reverse breakdown voltage increased from –166 V for the conventional HEMT to –196 V for the Er{sub 2}O{sub 3} MOS–HEMT. - Highlights: ► GaN/AlGaN/Er{sub 2}O{sub 3} metal-oxide semiconductor high electron mobility transistor ► Physical and electrical characteristics are presented. ► Electron beam evaporated Er{sub 2}O{sub 3} with excellent surface roughness ► Device exhibits reduced gate leakage current and improved I{sub ON}/I{sub OFF} ratio.

  12. Report on the stakes of strategic metals: the case of rare earth metals. Report of the 8 March 2011 public audition and of the presentation of conclusion on the 21 June 2011; Rapport sur les enjeux des metaux strategiques: le cas des terres rares. Compte rendu de l'audition publique du 8 mars 2011 et de la presentation des conclusions, le 21 juin 2011

    Energy Technology Data Exchange (ETDEWEB)

    Biraux, C.; Kert, Ch.

    2011-08-15

    The first part of this report proposes the content of a round table which gathered several experts in the field of rare earth metals (researchers, representatives of specialized branches companies like Saint-Gobain, Rhodia). The second part proposes the content of another round table which gathered experts who discussed the future of strategic metals like lithium, titanium or rhenium. Several issues are discussed: fundamental physics, physical and chemical properties, quantum physics, areas of interests (magnets, catalysis, ceramics, and photovoltaic arrays), availability, supplies and suppliers, processes, technological challenges and opportunities, and so on

  13. Synthesis and alkaline earth metal cation extraction by proton di-ionizable p-tert-butylcalix[4]arene-crown-5 compounds in cone, partial-cone and 1,3-alternate conformations.

    Science.gov (United States)

    Zhou, Hui; Surowiec, Kazimierz; Purkiss, David W; Bartsch, Richard A

    2006-03-21

    Synthetic strategies for novel, proton di-ionizable p-tert-butylcalix[4]arene-crown-5 compounds in cone, partial-cone and 1,3-alternate conformations are reported. Selective linkage of the two diametrical phenolic oxygens in p-tert-butylcalix[4]arene with tetraethylene glycol ditosylate gave 1,3-bridged p-tert-butylcalix[4]arene-crown-5. The two remaining phenolic units were alkylated using NaH and KH as the bases to give the cone and partial-cone conformers, respectively. Preparation of the 1,3-alternate conformers utilized a different sequence in which O-alkylation was followed by crown ether ring formation. Structures of these new ligands were elucidated by (1)H and (13)C NMR spectroscopy. These proton-ionizable ligands were tested for their solvent extraction properties toward alkaline earth metal cations. Surprising differences in their extraction behaviors are noted compared to those reported previously for di-ionizable p-tert-butylcalix[4]arenecrown-6 analogues.

  14. Trends in Syntheses, Structures, and Properties for Three Series of Ammine Rare-Earth Metal Borohydrides, M(BH4)3·nNH3 (M = Y, Gd, and Dy).

    Science.gov (United States)

    Jepsen, Lars H; Ley, Morten B; Černý, Radovan; Lee, Young-Su; Cho, Young Whan; Ravnsbæk, Dorthe; Besenbacher, Flemming; Skibsted, Jørgen; Jensen, Torben R

    2015-08-03

    Fourteen solvent- and halide-free ammine rare-earth metal borohydrides M(BH4)3·nNH3, M = Y, Gd, Dy, n = 7, 6, 5, 4, 2, and 1, have been synthesized by a new approach, and their structures as well as chemical and physical properties are characterized. Extensive series of coordination complexes with systematic variation in the number of ligands are presented, as prepared by combined mechanochemistry, solvent-based methods, solid-gas reactions, and thermal treatment. This new synthesis approach may have a significant impact within inorganic coordination chemistry. Halide-free metal borohydrides have been synthesized by solvent-based metathesis reactions of LiBH4 and MCl3 (3:1), followed by reactions of M(BH4)3 with an excess of NH3 gas, yielding M(BH4)3·7NH3 (M = Y, Gd, and Dy). Crystal structure models for M(BH4)3·nNH3 are derived from a combination of powder X-ray diffraction (PXD), (11)B magic-angle spinning NMR, and density functional theory (DFT) calculations. The structures vary from two-dimensional layers (n = 1), one-dimensional chains (n = 2), molecular compounds (n = 4 and 5), to contain complex ions (n = 6 and 7). NH3 coordinates to the metal in all compounds, while BH4(-) has a flexible coordination, i.e., either as a terminal or bridging ligand or as a counterion. M(BH4)3·7NH3 releases ammonia stepwise by thermal treatment producing M(BH4)3·nNH3 (6, 5, and 4), whereas hydrogen is released for n ≤ 4. Detailed analysis of the dihydrogen bonds reveals new insight about the hydrogen elimination mechanism, which contradicts current hypotheses. Overall, the present work provides new general knowledge toward rational materials design and preparation along with limitations of PXD and DFT for analysis of structures with a significant degree of dynamics in the structures.

  15. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  16. Metallic Hydrogen

    Science.gov (United States)

    Silvera, Isaac; Zaghoo, Mohamed; Salamat, Ashkan

    2015-03-01

    Hydrogen is the simplest and most abundant element in the Universe. At high pressure it is predicted to transform to a metal with remarkable properties: room temperature superconductivity, a metastable metal at ambient conditions, and a revolutionary rocket propellant. Both theory and experiment have been challenged for almost 80 years to determine its condensed matter phase diagram, in particular the insulator-metal transition. Hydrogen is predicted to dissociate to a liquid atomic metal at multi-megabar pressures and T =0 K, or at megabar pressures and very high temperatures. Thus, its predicted phase diagram has a broad field of liquid metallic hydrogen at high pressure, with temperatures ranging from thousands of degrees to zero Kelvin. In a bench top experiment using static compression in a diamond anvil cell and pulsed laser heating, we have conducted measurements on dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K. We observe a first-order phase transition in the liquid phase, as well as sharp changes in optical transmission and reflectivity when this phase is entered. The optical signature is that of a metal. The mapping of the phase line of this transition is in excellent agreement with recent theoretical predictions for the long-sought plasma phase transition to metallic hydrogen. Research supported by the NSF, Grant DMR-1308641, the DOE Stockpile Stewardship Academic Alliance Program, Grant DE-FG52-10NA29656, and NASA Earth and Space Science Fellowship Program, Award NNX14AP17H.

  17. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker;

    1970-01-01

    The magnetic field dependence of the energy of long- wavelength magnons in Tb-10%Ho has been studied by inelastic neutron scattering. The results agree with the `frozen-lattice' model, provided that the second-order magnetoelastic effect is taken into account. The planar anisotropy is almost...

  18. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  19. 12 Ministries Control Rare Earth Exports

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>"It is very natural to reserve rare earth as a strategic resource.Many countries do this,including China."On April 8,Sun Lihui,Vice Director of Metal Section of Chemicals Import & Export Commerce Chamber of China Minmetals Corporation told a reporter that as early as 2006,China has launched a strategic plan for rare earth,"but it was interrupted by the subsequent financial crisis."

  20. Timing And Processes Of Earth's Core Differentiation.

    Science.gov (United States)

    Allegre, C. J.; Manhes, G.; Gopel, C.

    2004-12-01

    Small 182W abundance excess of terrestrial W relative to W in bulk chondrites has been recently established (Yin et al. 2002, Kleine et al. 2002, Schoenberg et al. 2002). Rapid terrestrial accretion and early core formation, with completion of the bulk metal-silicate separation within less than 30 Myr have been proposed on this basis. These studies underline how much this 182W/182Hf time scale agrees with dynamic accretion models (Wetherill, 1986) that predict a ˜10 Myr interval for the main growth stage of Earth's formation. This W model time scale for terrestrial accretion is shorter than current estimates based on Pb isotope systematics of mantle-derived basalts and terrestrial Xe isotope systematics. The end of metal-silicate differentiation and large scale mantle degassing has been defined ˜100 My after beginning of the accretion. These studies also indicate agreement of this time scale with dynamic accretion models that predict 100 My for the end of Earth's accretion. The Hf-W time scale for accretion and core formation assumes total equilibration of incoming metal and silicate of impactors with the bulk silicate Earth (BSE) during planet's growth. Recently, the assumption of incomplete equilibration of metal and silicate components with BSE has been investigated (Halliday, 2004). It is proposed that impacting core material has not always efficiently mixed with the silicate portions of the Earth before being added to the Earth's core Our approach also considers that equilibration between metal and silicate has not been complete in BSE during Earth's growth, and we argue that early part of the Earth's core has segregated through unmelted silicate material. When the baby Earth was large enough, the increase of the temperature induced Fe-FeS eutectic melting. The liquid metal segregated through the crystalline silicate matrix and formed the early part of the Earth's core. Experimental study (Yoshino et al. 2003) indicates the percolation threshold for molten

  1. Oxidation catalysts on alkaline earth supports

    Science.gov (United States)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  2. Oxidation catalysts on alkaline earth supports

    Energy Technology Data Exchange (ETDEWEB)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  3. Earth from Above

    Science.gov (United States)

    Stahley, Tom

    2006-01-01

    Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

  4. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  5. 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...

  6. Geochemical Constraints on Core Formation in the Earth

    Science.gov (United States)

    Jones, John H.; Drake, Michael J.

    1986-01-01

    New experimental data on the partitioning of siderophile and chalcophile elements among metallic and silicate phases may be used to constrain hypotheses of core formation in the Earth. Three current hypotheses can explain gross features of mantle geochemistry, but none predicts siderophile and chalcophile element abundances to within a factor of two of observed values. Either our understanding of metal-silicate interactions and/or our understanding of the early Earth requires revision.

  7. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  8. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  9. GRNM Likely to Spearhead Reshuffle of Guangdong Rare Earth Industry

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>"Guangdong intends to build a rare earth platform named Guangdong Rare Earth Group, and the plan has been probably approved recently." An insider of local government said, "although there is no final conclusion, but the Guangdong’s intention to build a general platform of rare earth is clear." Since Guangdong Rising Nonferrous Metals Group Co., Ltd. (GRNM) is the only local state-owned enterprise leading

  10. Alkali-metal/alkaline-earth-metal fluorine beryllium borate NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} with large nonlinear optical properties in the deep-ultraviolet region

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A. H., E-mail: maalidph@yahoo.com [New Technologies—Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Huang, Hongwei [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Kamarudin, H. [Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Auluck, S. [Council of Scientific and Industrial Research—National Physical Laboratory, Dr. K S Krishnan Marg, New Delhi 110012, India and Physics Department, Indian Institute of Technology - Delhi, Hauz Khas, New Delhi 110016 (India)

    2015-02-28

    The linear optical response and second harmonic generation (SHG) in alkali-metal/alkaline-earth-metal fluorine beryllium borate NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} are investigated by means of density functional theory. Calculations are performed using four types of exchange correlations: Ceperley-Alder local density approximation, Perdew Burke and Ernzerhof general gradient approximation, Engel-Vosko generalized gradient approximation, and the recently modified Becke-Johnson potential (mBJ). The mBJ approach brings the calculated band gap (7.20 eV) in excellent agreement with the experimental one (7.28 eV). The calculated values of the uniaxial anisotropy δε=−0.076 and the birefringence Δn(0)=0.052 indicate considerable anisotropy in the linear optical properties, which makes it favorable for the second harmonic generation. The dominant component of the second harmonic generation is χ{sub 111}{sup (2)}(ω). The value of |χ{sub 111}{sup (2)}(ω)| is about 1.2 pm/V at λ = 1064 nm in agreement with previous calculations. To analyze the origin of the high SHG of NaSr{sub 3}Be{sub 3}B{sub 3}O{sub 9}F{sub 4} single crystals, we have correlated the features of |χ{sub 111}{sup (2)}(ω)| spectra with the features of ε{sub 2}(ω) spectra as a function of ω/2 and ω. From the calculated dominant component |χ{sub 111}{sup (2)}(ω)|, we find that the microscopic first hyperpolarizability, β{sub 111}, the vector components along the dipole moment direction is 0.5 × 10{sup −30} esu at static limit and 0.6 × 10{sup −30} esu at λ = 1064 nm.

  11. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples were...

  12. EarthKAM

    Data.gov (United States)

    National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...

  13. Earth on the Move.

    Science.gov (United States)

    Naturescope, 1987

    1987-01-01

    Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)

  14. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  15. China Not the Only Rare Earth Exporter

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Since China announced it was reducing exports of rare earth,there have been continuous voices in the international community demanding China expand exports or seek alternative resources. The United States has also complained to the WTO that China is hoarding the commodity. Subjected to scathing censure,what difficulties are facing China’s rare earth industry? When other countries seek alternative resources,how is the Chinese rare earth market affected? Economy&Nation Weekly,Xinhua News Agency’s finance magazine,recently interviewed Lin Donglu,Secretary General of the Chinese Society of Rare Earths,and Wang Hongqian, General Manager of China Non-Ferrous Metal Industry’s Foreign Engineering and Construction Co.Ltd.Edited excerpts follow

  16. Metals production

    Science.gov (United States)

    Beck, Theodore S.

    1992-02-01

    Existing procedures for design of electrochemical plants can be used for design of lunar processes taking into consideration the differences in environmental conditions. These differences include: 1/6 Earth gravity, high vacuum, solar electrical and heat source, space radiation heat sink, long days and nights, and different availability and economics of materials, energy, and labor. Techniques have already been developed for operation of relatively small scale hydrogen-oxygen fuel cell systems used in the U.S. lunar landing program. Design and operation of lunar aqueous electrolytic process plants appears to be within the state-of-the-art. Finding or developing compatible materials for construction and designing of fused-magma metal winning cells will present a real engineering challenge.

  17. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi [Wading River, NY

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  18. Capturing Near Earth Objects

    OpenAIRE

    Baoyin, Hexi; CHEN Yang; Li, Junfeng

    2011-01-01

    Recently, Near Earth Objects (NEOs) have been attracting great attention, and thousands of NEOs have been found to date. This paper examines the NEOs' orbital dynamics using the framework of an accurate solar system model and a Sun-Earth-NEO three-body system when the NEOs are close to Earth to search for NEOs with low-energy orbits. It is possible for such an NEO to be temporarily captured by Earth; its orbit would thereby be changed and it would become an Earth-orbiting object after a small...

  19. On the structures of the rare-earth metal germanides from the series REAl1-xGe3 (RE = Nd, Sm, Gd, Tb, Dy, Ho; 0.6 < x < 0.9). A tale of vacancies at the Al sites and the concomitant structural modulations.

    Science.gov (United States)

    Zhang, Jiliang; Liu, Yanyan; Shek, Chan Hung; Wang, Yingmin; Bobev, Svilen

    2017-07-18

    A series of ternary rare-earth metal aluminum germanides with the general formula REAl1-xGe3 (RE = Nd, Sm, Gd, Tb, Dy, and Ho; 0.6 < x < 0.9) have been synthesized by direct fusion of the corresponding elements. Their structures have been characterized by single-crystal X-ray diffraction and selected area electron diffraction methods. The average structure for all members is a representative of the orthorhombic SmNiGe3-type structure (Pearson symbol oS20, space group Cmmm), where the Al atoms occupy the Ni site, and the deep off-stoichiometry is due to statistical vacancies at this position. Considering long-range ordering of the vacancies, a monoclinic and a different orthorhombic structure, which represent idealized ordered variants, are possible, and the structural evolution depending on the nature of the rare-earth metals and the amount of vacancies at the aluminum site are discussed. Commensurate and incommensurate structural modulations based on these parent structures are also observed by electron diffraction, attesting to the great structural complexity in these systems. Magnetic susceptibility measurements are presented and discussed, along with the results from electronic band-structure calculations.

  20. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  1. Historical Uses of Meteoritic Metals as Precedent for Modern In-Situ Asteroid Mining

    Science.gov (United States)

    Krispin, D.; Mardon, A. A.; Fawcett, B. G.

    2016-08-01

    The strain on earth's resources of metal and the metallic density of meteorites mean that in situ asteroid mining is advisable. This has precedent: Use of meteoritic metal dates back to ancient times.

  2. The Earth's Magnetic Field

    OpenAIRE

    Edda Lína Gunnarsdóttir 1988

    2012-01-01

    The Earth's magnetic field is essential for life on Earth, as we know it, to exist. It forms a magnetic shield around the planet, protecting it from high energy particles and radiation from the Sun, which can cause damage to life, power systems, orbiting satellites, astronauts and spacecrafts. This report contains a general overview of the Earth's magnetic field. The different sources that contribute to the total magnetic field are presented and the diverse variations in the field are describ...

  3. Uderstanding Snowball Earth Deglaciation

    Science.gov (United States)

    Abbot, D. S.

    2012-12-01

    Earth, a normally clement planet comfortably in its star's habitable zone, suffered global or nearly global glaciation at least twice during the Neoproterozoic era (at about 635 and 710 million years ago). Viewed in the context of planetary evolution, these pan-global glaciations (Snowball Earth events) were extremely rapid, lasting only a few million years. The dramatic effect of the Snowball Earth events on the development of the planet can be seen through their link to rises in atmospheric oxygen and evolutionary innovations. These potential catastrophes on an otherwise clement planet can be used to gain insight into planetary habitability more generally. Since Earth is not currently a Snowball, a sound deglaciation mechanism is crucial for the viability of the Snowball Earth hypothesis. The traditional deglaciation mechanism is a massive build up of CO2 due to reduced weathering during Snowball Earth events until tropical surface temperatures reach the melting point. Once initiated, such a deglaciation might happen on a timescale of only dozens of thousands of years and would thrust Earth from the coldest climate in its history to the warmest. Therefore embedded in Snowball Earth events is an even more rapid and dramatic environmental change. Early global climate model simulations raised doubt about whether Snowball Earth deglaciation could be achieved at a CO2 concentration low enough to be consistent with geochemical data, which represented a potential challenge to the Snowball Earth hypothesis. Over the past few years dust and clouds have emerged as the essential missing additional processes that would allow Snowball Earth deglaciation at a low enough CO2 concentration. I will discuss the dust and cloud mechanisms and the modeling behind these ideas. This effort is critical for the broader implications of Snowball Earth events because understanding the specific deglaciation mechanism determines whether similar processes could happen on other planets.

  4. The Earth's early evolution.

    Science.gov (United States)

    Bowring, S A; Housh, T

    1995-09-15

    The Archean crust contains direct geochemical information of the Earth's early planetary differentiation. A major outstanding question in the Earth sciences is whether the volume of continental crust today represents nearly all that formed over Earth's history or whether its rates of creation and destruction have been approximately balanced since the Archean. Analysis of neodymium isotopic data from the oldest remnants of Archean crust suggests that crustal recycling is important and that preserved continental crust comprises fragments of crust that escaped recycling. Furthermore, the data suggest that the isotopic evolution of Earth's mantle reflects progressive eradication of primordial heterogeneities related to early differentiation.

  5. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    , Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...... of starlight by the Sun, and therefore directly observe the structure of space-time. This thesis explores several aspects of the observation of NEOs with Gaia, emphasising detection of NEOs and the quality of orbits computed from Gaia observations. The main contribution is the work on motion detection...

  6. Metal scarcity and sustainability, analyzing the necessity to reduce the extraction of scarce metals

    NARCIS (Netherlands)

    Henckens, M. L C M; Driessen, P. P J; Worrell, E.

    2014-01-01

    There is debate whether or not further growth of metal extraction from the earth's crust will be sustainable in connection with geologic scarcity. Will future generations possibly face a depletion of specific metals? We study whether, for which metals and to what extent the extraction rate would nee

  7. Metal scarcity and sustainability, analyzing the necessity to reduce the extraction of scarce metals

    NARCIS (Netherlands)

    Henckens, M. L C M; Driessen, P. P J|info:eu-repo/dai/nl/069081417; Worrell, E.|info:eu-repo/dai/nl/106856715

    2014-01-01

    There is debate whether or not further growth of metal extraction from the earth's crust will be sustainable in connection with geologic scarcity. Will future generations possibly face a depletion of specific metals? We study whether, for which metals and to what extent the extraction rate would

  8. 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...

  9. Rare Earth Additions in Continuously Cast Steel

    Science.gov (United States)

    Wilson, William G.; Heaslip, L. J.; Sommerville, I. D.

    1985-09-01

    Rare earth (lanthanide metals) addiiions to continuously cast steel are particularly advantageous because of their ability to refine as-cast structures, reduce segregation and increase hot ductility at temperatures just below that of solidification. The complete shape control of sulfides in steels containing Rare Earth Metals (REM), whether continuously cast or ingot cast, is primarily responsible for improvements in ductility related mechanical properties, weldability, fatigue resistance and resistance to hydrogen damage. Complete sulfide shape control can be obtained with REM additions at sulfur levels as high as.020%. The greatest improvements, however, are obtained with REM additions to low sulfur steels. However, to achieve full operational advantages afforded by REM, nozzle blockage problems must be circumvented. Water model studies indicate a possible solution.

  10. Earth Abundant Element Type I Clathrate Phases

    Directory of Open Access Journals (Sweden)

    Susan M. Kauzlarich

    2016-08-01

    Full Text Available Earth abundant element clathrate phases are of interest for a number of applications ranging from photovoltaics to thermoelectrics. Silicon-containing type I clathrate is a framework structure with the stoichiometry A8-xSi46 (A = guest atom such as alkali metal that can be tuned by alloying and doping with other elements. The type I clathrate framework can be described as being composed of two types of polyhedral cages made up of tetrahedrally coordinated Si: pentagonal dodecahedra with 20 atoms and tetrakaidecahedra with 24 atoms in the ratio of 2:6. The cation sites, A, are found in the center of each polyhedral cage. This review focuses on the newest discoveries in the group 13-silicon type I clathrate family: A8E8Si38 (A = alkali metal; E = Al, Ga and their properties. Possible approaches to new phases based on earth abundant elements and their potential applications will be discussed.

  11. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-08-22

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  12. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-02-07

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  13. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  14. The Earth's Core.

    Science.gov (United States)

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  15. Solid Earth: Introduction

    Science.gov (United States)

    Rummel, R.

    1991-10-01

    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  16. Versatile structures of group 13 metal halide complexes with 4,4'-bipy: from 1D coordination polymers to 2D and 3D metal-organic frameworks.

    Science.gov (United States)

    Sevastianova, Tatiana N; Bodensteiner, Michael; Maulieva, Albina F; Davydova, Elena I; Virovets, Alexander V; Peresypkina, Eugenia V; Balázs, Gábor; Graßl, Christian; Seidl, Michael; Scheer, Manfred; Frenking, Gernot; Berezovskaya, Ekaterina A; Kazakov, Igor V; Khoroshilova, Olesya V; Timoshkin, Alexey Y

    2015-12-21

    A systematic structural study of complexes formed by aluminium and gallium trihalides with 4,4'-bipyridine (bipy) in 2 : 1, 1 : 1, and 1 : 2 stoichiometric ratios has been performed. Molecular structures of 11 complexes in the solid state have been determined for the first time. Complexes of 2 : 1 composition are molecular, while complexes of 1 : 1 composition form metal-organic frameworks of different kinds: an ionic 3D network (three interpenetrated lvt nets for AlCl3bipy), an ionic 2D network for AlBr3bipy and GaBr3bipy and a 1D coordination polymer in the case of GaCl3bipy. Thus, the nature of the Lewis acid plays a critical role in the structural type of the complex in the solid state. Incorporation of excess bipy molecules into (GaCl3bipy)∞ (formation of crystallosolvate) leads to an unprecedented change of the molecular structure from a non-ionic 1D coordination polymer to an ionic 2D metal organic framework [GaCl2bipy2](+)[GaCl4](-)·2bipy. As indicated by the temperature-dependent XRD study, removal of bipy by heating in a vacuum restores the non-ionic 1D structure. Quantum chemical computations for simple cluster model systems (up to eight Al and Ga atoms) reveal that ionic forms are slightly favourable, although the energy differences between the ionic and non-ionic structures are not large. These theoretical predictions are in good agreement with experimental findings. Thus, even relatively simple cluster models may be used to indicate the structural preferences in the solid state. Both experimental and computational IR frequency shifts of the in-plane ring bending mode of bipy upon complexation correlate well with the M-N bond distances in the complexes.

  17. The earth orbiting space debris

    Directory of Open Access Journals (Sweden)

    Rossi A.

    2005-01-01

    Full Text Available The space debris population is similar to the asteroid belt, since it is subject to a process of high-velocity mutual collisions that affects the long-term evolution of its size distribution. Presently, more than 10 000 artificial debris particles with diameters larger than 10 cm (and more than 300 000 with diameters larger than 1 cm are orbiting the Earth, and are monitored and studied by a large network of sensors around the Earth. Many objects of different kind compose the space debris population, produced by different source mechanisms ranging from high energy fragmentation of large spacecraft to slow diffusion of liquid metal. The impact against a space debris is a serious risk that every spacecraft must face now and it can be evaluated with ad-hoc algorithms. The long term evolution of the whole debris population is studied with computer models allowing the simulation of all the known source and sink mechanisms. One of these codes is described in this paper and the evolution of the debris environment over the next 100 years, under different traffic scenarios, is shown, pointing out the possible measures to mitigate the growth of the orbital debris population. .

  18. Earth as art three

    Science.gov (United States)

    ,

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  19. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  20. Accretion of the Earth.

    Science.gov (United States)

    Canup, Robin M

    2008-11-28

    The origin of the Earth and its Moon has been the focus of an enormous body of research. In this paper I review some of the current models of terrestrial planet accretion, and discuss assumptions common to most works that may require re-examination. Density-wave interactions between growing planets and the gas nebula may help to explain the current near-circular orbits of the Earth and Venus, and may result in large-scale radial migration of proto-planetary embryos. Migration would weaken the link between the present locations of the planets and the original provenance of the material that formed them. Fragmentation can potentially lead to faster accretion and could also damp final planet orbital eccentricities. The Moon-forming impact is believed to be the final major event in the Earth's accretion. Successful simulations of lunar-forming impacts involve a differentiated impactor containing between 0.1 and 0.2 Earth masses, an impact angle near 45 degrees and an impact speed within 10 per cent of the Earth's escape velocity. All successful impacts-with or without pre-impact rotation-imply that the Moon formed primarily from material originating from the impactor rather than from the proto-Earth. This must ultimately be reconciled with compositional similarities between the Earth and the Moon.

  1. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.

  2. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.The talk will present an overview of current efforts in ESI, the role members of IEEE GRSS play, and discuss

  3. Hydrometallurgical method for recycling rare earth metals, cobalt, nickel, iron, and manganese from negative electrodes of spent Ni-MH mobile phone batteries; Metodo hidrometalurgico para reciclagem de metais terras raras, cobalto, niquel, ferro e manganes de eletrodos negativos de baterias exauridas de Ni-MH de telefone celular

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Vinicius Emmanuel de Oliveira dos; Lelis, Maria de Fatima Fontes; Freitas, Marcos Benedito Jose Geraldo de, E-mail: viniciusemmanuel@hotmail.com [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Quimica; Celante, Vinicius Guilherme [Instituto Federal do Espirito Santo (IFES), Aracruz, ES (Brazil)

    2014-07-01

    A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni-MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO{sub 4}){sub 2}.H{sub 2}O) and lanthanum sulfate (La{sub 2}(SO{sub 4}){sub 3}.H{sub 2}O) as the major recovered components. Iron was recovered as Fe(OH){sub 3} and FeO. Manganese was obtained as Mn{sub 3}O{sub 4}.The recovered Ni(OH){sub 2} and Co(OH){sub 2} were subsequently used to synthesize LiCoO{sub 2}, LiNiO{sub 2} and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques. (author)

  4. 稀土对金属纳米粒子-介质复合薄膜(Ag-BaO)光电发射性能的增强%ENHANCED PHOTOEMISSION FROM METAL NANOPARTICLE COMPOSITE THIN FILMS (Ag-BaO) DOPED WITH RARE-EARTH ELEMENTS

    Institute of Scientific and Technical Information of China (English)

    许北雪; 吴锦雷; 刘惟敏; 杨海; 邵庆益; 刘盛; 薛增泉; 吴全德

    2001-01-01

    用真空蒸发沉积的方法制备了掺杂稀土的金属纳米粒子-介质复 合薄膜(Ag-BaO薄膜). 与不掺杂稀土的Ag-BaO薄膜相比,其光电发射能力提高了近40%. 透射电镜分析表明,掺杂稀土后,Ag-BaO薄膜中的Ag纳米粒子明显细化、球化、密度增大 . 这表明Ag纳米粒子的细化,使得其在光作用下,光电子更容易通过隧道效应穿过界面位垒 逸出,导致光电发射能力增强.%A metal nanoparticles-composite thin film (Ag-BaO), doped by rare-earth eleme nts, was g rown by vacuum deposition. Compared with the normal Ag-BaO thin film, the photo emission current of the doped Ag-BaO thin film increases by about 40%. The tran smi ssion electron micrograph indicated that Ag nanoparticles become smaller when do ped with rare-earth. With the smaller size of Ag nanoparticles, photoelect rons are eas ier to transgress from Ag nanoparticles via tunnel effect. Thus the photomission current increases.

  5. Earth before life.

    Science.gov (United States)

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-09

    A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome includes the age of the Earth are consistent with observed data. The appearance of life after the formation of the Earth is consistent with the data set under examination.

  6. Sulfur in Earth's Mantle and Its Behavior During Core Formation

    Science.gov (United States)

    Chabot, Nancy L.; Righter,Kevin

    2006-01-01

    The density of Earth's outer core requires that about 5-10% of the outer core be composed of elements lighter than Fe-Ni; proposed choices for the "light element" component of Earth's core include H, C, O, Si, S, and combinations of these elements [e.g. 1]. Though samples of Earth's core are not available, mantle samples contain elemental signatures left behind from the formation of Earth's core. The abundances of siderophile (metal-loving) elements in Earth's mantle have been used to gain insight into the early accretion and differentiation history of Earth, the process by which the core and mantle formed, and the composition of the core [e.g. 2-4]. Similarly, the abundance of potential light elements in Earth's mantle could also provide constraints on Earth's evolution and core composition. The S abundance in Earth's mantle is 250 ( 50) ppm [5]. It has been suggested that 250 ppm S is too high to be due to equilibrium core formation in a high pressure, high temperature magma ocean on early Earth and that the addition of S to the mantle from the subsequent accretion of a late veneer is consequently required [6]. However, this earlier work of Li and Agee [6] did not parameterize the metalsilicate partitioning behavior of S as a function of thermodynamic variables, limiting the different pressure and temperature conditions during core formation that could be explored. Here, the question of explaining the mantle abundance of S is revisited, through parameterizing existing metal-silicate partitioning data for S and applying the parameterization to core formation in Earth.

  7. Whole-Earth Decompression Dynamics

    OpenAIRE

    Herndon, J. Marvin

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The i...

  8. Earth rotation and geodynamics

    Science.gov (United States)

    Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta

    2015-12-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth' magnetic field.

  9. Earth science: Extraordinary world

    Science.gov (United States)

    Day, James M. D.

    2016-09-01

    The isotopic compositions of objects that formed early in the evolution of the Solar System have been found to be similar to Earth's composition -- overturning notions of our planet's chemical distinctiveness. See Letters p.394 & p.399

  10. Gambling with the earth

    CERN Multimedia

    Muir, H

    2000-01-01

    The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).

  11. Astronomy: Earth's seven sisters

    Science.gov (United States)

    Snellen, Ignas A. G.

    2017-02-01

    Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets. See Letter p.456

  12. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ July 20~31 Rare earth market still went downward, which was mainly led by sluggish demand for didymium products. Weak demand by domestic NdFeB market was attributed to continuous price falling of didymium mischmetal.

  13. Analyzing earth's surface data

    Science.gov (United States)

    Barr, D. J.; Elifrits, C. D.

    1979-01-01

    Manual discusses simple inexpensive image analysis technique used to interpret photographs and scanner of data of Earth's surface. Manual is designed for those who have no need for sophisticated computer-automated analysis procedures.

  14. Managing Planet Earth.

    Science.gov (United States)

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  15. Earliest life on earth

    CERN Document Server

    Golding, Suzanne D

    2010-01-01

    This volume integrates the latest findings on earliest life forms, identified and characterized in some of the oldest rocks on Earth. It places emphasis on the integration of analytical methods with observational techniques and experimental simulations.

  16. Earth/Lands

    OpenAIRE

    2011-01-01

    Earth is an essentially original and misunderstood raw material with great potential, from the positive environmental and energy ratio, to its admirable capacity to integrate other materials such as stone, wood, brick, lime, vegetable fibres, etc., capable also of constituting the sole material for whole buildings in climactical and geographically extreme situations. Earth offers a great capacity to respond to the housing needs of millions of human beings, not only quantitative needs compa...

  17. Earth rotation and geodynamics

    OpenAIRE

    Bogusz Janusz; Brzezinski Aleksander; Kosek Wieslaw; Nastula Jolanta

    2015-01-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals wit...

  18. Toward other Earths

    Science.gov (United States)

    Hatzes, Artie P.

    2016-04-01

    How common are habitable Earth-like planets? This is a key question that drives much of current research in exoplanets. To date, we have discovered over one thousand exoplanets, mostly through the transit method. Among these are Earth-size planets, but these orbit very close to the star (semi-major axis approximately 0.01 Astronomical Units). Potentially rocky planets have also been discovered in a star's habitable zone, but these have approximately twice the radius of the Earth. These certainly do not qualify as Earth "twins". Several hundreds of multi-planet systems have also been discovered, but these are mostly ultra-compact systems with up to seven planets all with orbital distances less than that of Mercury in our solar system. The detection of a planetary system that is the direct analog of our solar system still eludes us. After an overview of the current status of exoplanet discoveries I will discuss the prospects and challenges of finding such Earth analogs from the ground and from future space missions like PLATO. After over two decades of searching, we may well be on the brink of finding other Earths.

  19. Non-terrestrial resources of economic importance to earth

    Science.gov (United States)

    Lewis, John S.

    1991-01-01

    The status of research on the importation of energy and nonterrestrial materials is reviewed, and certain specific directions for new research are proposed. New technologies which are to be developed include aerobraking, in situ propellant production, mining and beneficiation of extraterresrrial minerals, nuclear power systems, electromagnetic launch, and solar thermal propulsion. Topics discussed include the system architecture for solar power satellite constellations, the return of nonterrestrial He-3 to earth for use as a clean fusion fuel, and the return to earth of platinum-group metal byproducts from processing of nonterrestrial native ferrous metals.

  20. Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data

    CERN Document Server

    Lawler, J E; Cowan, J J; Ivans, I I; Hartog, E A Den

    2009-01-01

    Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log epsilon = 1.61 +/- 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17 3248, CS 22892-052, CS 31082-001, HD 115444 and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of 0.01 dex similar to the Solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process ...

  1. Metal hyperaccumulation in plants.

    Science.gov (United States)

    Krämer, Ute

    2010-01-01

    During the history of life on Earth, tectonic and climatic change repeatedly generated large territories that were virtually devoid of life and exhibited harsh environmental conditions. The ability of a few specialist pioneer plants to colonize such hostile environments was thus of paramount ecological importance for the continuous maintenance of primary production over time. Yet, we know very little about how extreme traits evolve and function in plants. Recent breakthroughs have given first insights into the molecular basis underlying the complex extreme model trait of metal hyperaccumulation and associated metal hypertolerance. This review gives an introduction into the hyperaccumulator research field and its history; provides an overview of hyperaccumulator germplasm; describes the state of the art of our understanding of the physiological, molecular, and genetic basis underlying metal hyperaccumulation and its evolution; and highlights future research needs and opportunities.

  2. Advances on Rare Earth Application in Pollution Ecology

    Institute of Scientific and Technical Information of China (English)

    Huang Xiaohua; Zhou Qing; Zhang Guangsheng

    2005-01-01

    The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc. in environment. The authors suggest that the mechanism of rare earth to inducing plant resistance and reducing plant injury is to control biochemical metabolism web in plant cell, to adjust its protection system of free radical, to maintain its photosynthesis, to protect cell membrane system and to carry through its function on mineral metabolism. Meanwhile some problems in the field were discussed as well.

  3. Protecting the environment and public health from rare earth mining

    Science.gov (United States)

    Huang, Xiang; Zhang, Guochun; Pan, An; Chen, Fengying; Zheng, Chunli

    2016-11-01

    As increasing demand for green energy and high-tech devices grows, so does the rising prospecting of rare earth metals required for their production. Protecting the environment and public health from rare earth element (REE) mining as well as emerging pollutants is urgently required to achieve sustainable development. This study mapped Earth's hidden REE deposits to identify potential contamination hotspots with the aim of preventing its deleterious effects on the environment. We worry that there would be widespread tailing facilities concomitant with serious pollutions, such as the Bayan Obo tailings site, and argue that a tradeoff between the underground REE exploration and environment conservation should be reached as soon as possible.

  4. Announcement of Resolutions at the 15th Meeting of the 3rd Session of the Board of Directors of Baogang Rare Earth(continued)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ 4. Proposal on Production Expansion of Baotou Rewin Rare Earth Metallic Materials Co., Lid To further enlarge production capacity of neodymium (didymium) metal of Baotou Rewin Rare Earth Metallic Materials Co., Ltd, which is a holding company of Baogang Rare Earth (Baogang Rare Earth holds 58.42% of the shares of Rewin), enhance local utilization rate of neodymium (didymium) oxide inside Baogang Rare Earth and ensure raw materials supply for future development of NdFeB magnetic materials of Baogang Rare Earth, Baogang Rare Earth approves the project of "Investment of Rewin in production expansion of 3,000 tons of neodymium (didymium) metal per annum". Production capacity of neodymium (didymium) metal of Rewin will approach 8,000 tons/year.

  5. 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.

  6. Hydrogen Storage in Nanostructured Light Metal Hydrides

    NARCIS (Netherlands)

    Singh, S.

    2009-01-01

    The global energy issues can be solved by the abundantly available hydrogen on earth. Light metals are a compact and safe medium for storing hydrogen. This makes them attractive for vehicular use. Unfortunately, hydrogen uptake and release is slow in light metals at practical temperature and pressur

  7. Hydrogen Storage in Nanostructured Light Metal Hydrides

    NARCIS (Netherlands)

    Singh, S.

    2009-01-01

    The global energy issues can be solved by the abundantly available hydrogen on earth. Light metals are a compact and safe medium for storing hydrogen. This makes them attractive for vehicular use. Unfortunately, hydrogen uptake and release is slow in light metals at practical temperature and

  8. Anthropogenic Cycles of Rare Earth Elements

    Science.gov (United States)

    Du, X.; Graedel, T. E.

    2009-12-01

    This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from

  9. Hydrogenation of the rare earth alloys for production negative electrodes of nickel-metal hydride batteries; Hidrogenacao de ligas a base de terras raras para fabricacao de eletrodos negativos de baterias de niquel-hidreto metalico

    Energy Technology Data Exchange (ETDEWEB)

    Casini, Julio Cesar Serafim

    2011-07-01

    In this work were studied of La{sub 0.7-x}Mg{sub x} Pr{sub 0.3}Al{sub 0.3}Mn{sub 0.4}Co{sub 0.5}Ni{sub 3.8} (X = 0 and 0.7) alloys for negative electrodes of the nickel-metal hydride batteries. The hydrogenation of the alloys was performed varying pressing of H{sub 2} (2 and 10 bar) and temperature (room and 500 Degree-Celsius ). The discharge capacity of the nic kel-metal hydride batteries were analyzed in ARBIN BT- 4 electrical test equipment. The as-cast alloys were analyzed by scanning electron microscopy (SEM), energy disperse spectroscopy (EDX) and X-Ray diffraction. The increasing Mg addition in the alloy increases maximum discharge capacity but decrease cycle life of the batteries. The maximum discharge capacity was obtained with the Mg{sub 0.7}Pr{sub 0.3}Al{sub 0.3}Mn{sub 0.4}Co{sub 0.5}Ni{sub 3.8} alloy (60 mAh) and the battery which presented the best performance was La{sub 0.4}Mg{sub 0.3}Pr{sub 0.3}Al{sub 0.3}Mn{sub 0.4}Co{sub 0.5}Ni{sub 3.8} alloy (53 mAh and 150 cycles). The H{sub 2} capability of absorption was diminished for increased Mg addition and no such effect occurs for Mg{sub 0.7}Pr{sub 0.3}Al{sub 0.3}Mn{sub 0.4}Co{sub 0.5}Ni{sub 3.8} alloy. (author)

  10. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  11. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  12. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  13. New transition metal-rich rare-earth palladium/platinum aluminides with RET{sub 5}Al{sub 2} composition. Structure, magnetism and {sup 27}Al NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Stegemann, Frank; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie

    2015-06-01

    REPd{sub 5}Al{sub 2} compounds with RE = Ce-Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements (RE = Tb-Yb) had not been prepared. We report on the missing members of the REPd{sub 5}Al{sub 2} (RE = Tb-Yb) series as well as on the new REPt{sub 5}Al{sub 2} (RE = Y, Gd-Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi{sub 2}Al{sub 5} type with an anti-arrangement of the T = Pd/Pt and Al atoms. YPd{sub 5}Al{sub 2} and LuPd{sub 5}Al{sub 2}, as well as the respective platinum homologs, YPt{sub 5}Al{sub 2} and LuPt{sub 5}Al{sub 2}, have been characterized also by {sup 27}Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.

  14. Coordination of alkaline earth metal ions in the inverted cucurbit[7]uril supramolecular assemblies formed in the presence of [ZnCl4]2- and [CdCl4]2-.

    Science.gov (United States)

    Li, Qing; Zhang, Yun-Qian; Zhu, Qian-Jiang; Xue, Sai-Feng; Tao, Zhu; Xiao, Xin

    2015-05-01

    A convenient method to isolate inverted cucurbit[7]uril (iQ[7]) from a mixture of water-soluble Q[n]s was established by eluting the soluble mixture of Q[n]s on a Dowex (H(+) form) column so that iQ[7] could be selected as a ligand for coordination and supramolecular assembly with alkaline earth cations (AE(2+)) in aqueous HCl solutions in the presence of [ZnCl(4)](2-) and [CdCl(4)](2-) anions as structure-directing agents. Single-crystal X-ray diffraction analysis revealed that both iQ[7]-AE(2+) -[ZnCl(4)](2-) -HCl and iQ[7]-AE(2+) -[CdCl(4)](2-) -HCl interaction systems yielded supramolecular assemblies, in which the [ZnCl(4)](2-) and [CdCl(4)](2-) anions presented a honeycomb effect, and this resulted in the formation of linear iQ[7]/AE(2+) coordination polymers through outer-surface interactions of Q[n]s.

  15. 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%.

  16. Better Than Earth

    CERN Document Server

    Heller, René

    2015-01-01

    Do We Inhabit The Best O All Possible Worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  17. Better Than Earth

    Science.gov (United States)

    Heller, René

    2015-01-01

    Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  18. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  19. How Big is Earth?

    Science.gov (United States)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  20. Zeolite-like metal-organic frameworks with ana topology

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-20

    Embodiments of the present disclosure describe a zeolite-like metal-organic framework composition comprising a metal-organic framework composition with ana topology characterized by the formula [MIII(4, 5-imidazole dicarboxylic acid)2X(solvent)a]n wherein MIII comprises a trivalent cation of a rare earth element, X comprises an alkali metal element or alkaline earth metal element, and solvent comprises a guest molecule occupying pores. Embodiments of the present disclosure describe a method of separating paraffins comprising contacting a zeolite-like metal-organic framework with ana topology with a flow of paraffins, and separating the paraffins by size.