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Sample records for active rare earth

  1. Crystalline rare-earth activated oxyorthosilicate phosphor

    DOEpatents

    McClellan, Kenneth J.; Cooke, D. Wayne

    2004-02-10

    Crystalline, transparent, rare-earth activated lutetium oxyorthosilicate phosphor. The phosphor consists essentially of lutetium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of lutetium gadolinium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Gd.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of gadolinium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Gd(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor may be optically coupled to a photodetector to provide a radiation detector.

  2. Antibacterial, Antifungal and Nematicidal Activities of Rare Earth Ions.

    PubMed

    Wakabayashi, Tokumitsu; Ymamoto, Ayumi; Kazaana, Akira; Nakano, Yuta; Nojiri, Yui; Kashiwazaki, Moeko

    2016-12-01

    Despite the name, rare earth elements are relatively abundant in soil. Therefore, these elements might interact with biosphere during the history of life. In this study, we have examined the effect of rare earth ions on the growth of bacteria, fungi and soil nematode. All rare earth ions, except radioactive promethium that we have not tested, showed antibacterial and antifungal activities comparable to that of copper ions, which is widely used as antibacterial metals in our daily life. Rare earth ions also have nematicidal activities as they strongly perturb the embryonic development of the nematode, Caenorhabditis elegans. Interestingly, the nematicidal activity increased with increasing atomic number of lanthanide ions. Since the rare earth ions did not show high toxicity to the human lymphoblastoid cell line or even stimulate the growth of the cultured cells at 1 mM, it raised the possibility that we can substitute rare earth elements for the antibacterial metals usually used because of their safety.

  3. BOREHOLE NEUTRON ACTIVATION: THE RARE EARTHS.

    USGS Publications Warehouse

    Mikesell, J.L.; Senftle, F.E.

    1987-01-01

    Neutron-induced borehole gamma-ray spectroscopy has been widely used as a geophysical exploration technique by the petroleum industry, but its use for mineral exploration is not as common. Nuclear methods can be applied to mineral exploration, for determining stratigraphy and bed correlations, for mapping ore deposits, and for studying mineral concentration gradients. High-resolution detectors are essential for mineral exploration, and by using them an analysis of the major element concentrations in a borehole can usually be made. A number of economically important elements can be detected at typical ore-grade concentrations using this method. Because of the application of the rare-earth elements to high-temperature superconductors, these elements are examined in detail as an example of how nuclear techniques can be applied to mineral exploration.

  4. Rare earths

    USGS Publications Warehouse

    Gambogi, J.

    2013-01-01

    Global mine production of rare earths was estimated to have declined slightly in 2012 relative to 2011 (Fig. 1). Production in China was estimated to have decreased to 95 from 105 kt (104,700 from 115,700 st) in 2011, while new mine production in the United States and Australia increased.

  5. Rare earth activated yttrium aluminate phosphors with modulated luminescence.

    PubMed

    Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

    2016-06-01

    Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd.

  6. Complex Electronic Structure of Rare Earth Activators in Scintillators

    SciTech Connect

    Aberg, D.; Yu, S. W.; Zhou, F.

    2015-10-27

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

  7. Precise trace rare earth analysis by radiochemical neutron activation

    SciTech Connect

    Laul, J.C.; Lepel, E.A.; Weimer, W.C.; Wogman, N.A.

    1981-06-01

    A rare earth group separation scheme followed by normal Ge(Li), low energy photon detector (LEPD), and Ge(Li)-NaI(Tl) coincidence-noncoincidence spectrometry significantly enhances the detection sensitivity of individual rare earth elements (REE) at or below the ppB level. Based on the selected ..gamma..-ray energies, normal Ge(Li) counting is favored for /sup 140/La, /sup 170/Tb, and /sup 169/Yb; LEPD is favored for low ..gamma..-ray energies of /sup 147/Nd, /sup 153/Sm, /sup 166/Ho, and /sup 169/Yb; and noncoincidence counting is favored for /sup 141/Ce, /sup 143/Ce, /sup 142/Pr, /sup 153/Sm, /sup 171/Er, and /sup 175/Yb. The detection of radionuclides /sup 152m/Eu, /sup 159/Gd, and /sup 177/Lu is equally sensitive by normal Ge(Li) and noncoincidence counting; /sup 152/Eu is equally sensitive by LEPD and normal Ge(Li); and /sup 153/Gd and /sup 170/Tm is equally favored by all the counting modes. Overall, noncoincidence counting is favored for most of the REE. Precise measurements of the REE were made in geological and biological standards.

  8. Rare earth gas laser

    DOEpatents

    Krupke, W.F.

    1975-10-31

    A high energy gas laser with light output in the infrared or visible region of the spectrum is described. Laser action is obtained by generating vapors of rare earth halides, particularly neodymium iodide or, to a lesser extent, neodymium bromide, and disposing the rare earth vapor medium in a resonant cavity at elevated temperatures; e.g., approximately 1200/sup 0/ to 1400/sup 0/K. A particularly preferred gaseous medium is one involving a complex of aluminum chloride and neodymium chloride, which exhibits tremendously enhanced vapor pressure compared to the rare earth halides per se, and provides comparable increases in stored energy densities.

  9. Advances in the theoretical understanding of photon upconversion in rare-earth activated nanophosphors.

    PubMed

    Liu, Guokui

    2015-03-21

    Photon upconversion in rare earth activated phosphors involves multiple mechanisms of electronic transitions. Stepwise optical excitation, energy transfer, and various nonlinear and collective light-matter interaction processes act together to convert low-energy photons into short-wavelength light emission. Upconversion luminescence from nanomaterials exhibits additional size and surface dependencies. A fundamental understanding of the overall performance of an upconversion system requires basic theories on the spectroscopic properties of solids containing rare earth ions. This review article surveys the recent progress in the theoretical interpretations of the spectroscopic characteristics and luminescence dynamics of photon upconversion in rare earth activated phosphors. The primary aspects of upconversion processes, including energy level splitting, transition probability, line broadening, non-radiative relaxation and energy transfer, are covered with an emphasis on interpreting experimental observations. Theoretical models and methods for analyzing nano-phenomena in upconversion are introduced with detailed discussions on recently reported experimental results.

  10. Determination of contamination in rare earth materials by promptgamma activation analysis (PGAA)

    SciTech Connect

    Perry, D.L.; English, G.A.; Firestone, R.B.; Molnar, G.L.; Revay,Zs.

    2004-11-09

    Prompt gamma activation analysis (PGAA) has been used to detect and quantify impurities in the analyses of rare earth (RE) oxides. The analytical results are discussed with respect to the importance of having a thorough identification and understanding of contaminant elements in these compounds regarding the function of the materials in their various applications. Also, the importance of using PGAA to analyze materials in support of other physico-chemical studies of the materials is discussed, including the study of extremely low concentrations of ions such as the rare earth ions themselves in bulk material matrices.

  11. Rare earth thermoelectrics

    SciTech Connect

    Mahan, G.D.

    1997-09-01

    The author reviews the thermoelectric properties of metallic compounds which contain rare-earth atoms. They are the group of metals with the largest value ever reported of the Seebeck coefficient. An increase by 50% of the Seebeck would make these compounds useful for thermoelectric devices. The largest Seebeck coefficient is found for compounds of cerium (e.g., CePd{sub 3}) and ytterbium (e.g., YbAl{sub 3}). Theoretical predictions are in agreement with the maximum observed Seebeck. The author discusses the theoretical model which has been used to calculate the Seebeck coefficient. He is solving this model for other configurations (4f){sup n} of rare-earth ground states.

  12. Dinitrogen reduction via photochemical activation of heteroleptic tris(cyclopentadienyl) rare-earth complexes.

    PubMed

    Fieser, Megan E; Bates, Jefferson E; Ziller, Joseph W; Furche, Filipp; Evans, William J

    2013-03-13

    Dinitrogen can be reduced by photochemical activation of the Ln(3+) mixed-ligand tris(cyclopentadienyl) rare-earth complexes (η(5)-C5Me5)(3-x)(C5Me4H)(x)Ln (Ln = Y, Lu, Dy; x = 1, 2). [(C5Me4R)2Ln]2(μ-η(2):η(2)-N2) products (R = H, Me) are formed in reactions in which N2 is reduced to (N═N)(2-) and (C5Me4H)(-) is oxidized to (C5Me4H)2. Density functional theory indicates that this unusual example of rare-earth photochemistry can be rationalized by absorptions involving the (η(3)-C5Me4H)(-) ligands.

  13. Neutron Activation Analysis of the Rare Earth Elements (REE) - With Emphasis on Geological Materials

    NASA Astrophysics Data System (ADS)

    Stosch, Heinz-Günter

    2016-08-01

    Neutron activation analysis (NAA) has been the analytical method of choice for rare earth element (REE) analysis from the early 1960s through the 1980s. At that time, irradiation facilitieswere widely available and fairly easily accessible. The development of high-resolution gamma-ray detectors in the mid-1960s eliminated, formany applications, the need for chemical separation of the REE from the matrix material, making NAA a reliable and effective analytical tool. While not as precise as isotopedilution mass spectrometry, NAA was competitive by being sensitive for the analysis of about half of the rare earths (La, Ce, Nd, Sm, Eu, Tb, Yb, Lu). The development of inductively coupled plasma mass spectrometry since the 1980s, together with decommissioning of research reactors and the lack of installation of new ones in Europe and North America has led to the rapid decline of NAA.

  14. Synthesis, characterization and photocatalytic activities of rare earth-loaded BiVO 4 catalysts

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Wu, Chundu; Li, Huaming; Chu, Jinyu; Sun, Guangsong; Xu, Yuanguo; Yan, Yongsheng

    2009-11-01

    The BiVO 4-based photocatalysts loaded with rare earth (RE=Ho, Sm, Yb, Eu, Gd, Nd, Ce and La) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), nitrogen adsorption for the BET specific surface area and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by decolorization of methylene blue (MB) under visible light irradiation. The results of XRD, SEM and XPS analysis deduced that the rare earth ions were present as RE 2O 3 in the samples. The DRS analysis showed the shift in the absorbption edge from the UV to the visible range: Ho 3+-BiVO 4 < Sm 3+-BiVO 4 < Yb 3+-BiVO 4 < Eu 3+-BiVO 4 < Gd 3+-BiVO 4 < Nd 3+-BiVO 4 < La 3+-BiVO 4 < Ce 3+-BiVO 4 < BiVO 4. Gd 3+-BiVO 4 had the highest photocatalytic activity among all the RE 3+-BiVO 4 catalysts. The optimal Gd content was 8 at% under visible light irradiation. This beneficial effect was attributed to the specific electron structure characteristics of gadolinium and the increasing in the separation efficiency of the electron-hole pairs. On the contrast, the other rare earth ions had the detrimental effect on the photocatalytic decolorization of MB.

  15. Ames Lab 101: Rare Earths

    ScienceCinema

    Gschneidner, Karl

    2016-07-12

    "Mr. Rare Earth," Ames Laboratory scientist Karl Gschneidner Jr., explains the importance of rare-earth materials in many of the technologies we use today -- ranging from computers to hybrid cars to wind turbines. Gschneidner is a world renowned rare-earths expert at the U.S. Department of Energy's Ames Laboratory.

  16. Ames Lab 101: Rare Earths

    SciTech Connect

    Gschneidner, Karl

    2010-01-01

    "Mr. Rare Earth," Ames Laboratory scientist Karl Gschneidner Jr., explains the importance of rare-earth materials in many of the technologies we use today -- ranging from computers to hybrid cars to wind turbines. Gschneidner is a world renowned rare-earths expert at the U.S. Department of Energy's Ames Laboratory.

  17. Phosphate glass core/silica clad fibres with a high concentration of active rare-earth ions

    NASA Astrophysics Data System (ADS)

    Egorova, O. N.; Galagan, B. I.; Denker, B. I.; Sverchkov, S. E.; Semjonov, S. L.

    2016-12-01

    We report a study of silica-clad composite optical fibres having a phosphate glass core doped with active rare-earth elements. The phosphate glass core allows a high concentration of active rare-earth ions to be obtained, and the silica cladding ensures high mechanical strength and facilitates fusion splicing of such fibres to silica fibres. Owing to the high concentration of active rare-earth ions, this type of fibre is potentially attractive for applications where a small cavity length and high lasing efficiency are needed.

  18. Excited state absorption in glasses activated with rare earth ions: Experiment and modeling

    NASA Astrophysics Data System (ADS)

    Piatkowski, Dawid; Mackowski, Sebastian

    2012-10-01

    We present semiempirical approach based on the Judd-Ofelt theory and apply it for modeling the spectral properties of fluoride glasses activated with the rare earth (RE) ions. This method provide a powerful tool for simulating both ground state absorption (GSA) and excited state absorption (ESA) spectra of RE ions, e.g. Nd3+, Ho3+, Er3+ and Tm3+ in the ZBLAN glass matrix. The results of theoretical calculations correspond to the experimentally measured data. We also demonstrate that the spectra obtained using the presented approach are applicable in the analysis of up-conversion excitation schemes in these optoelectronically relevant materials.

  19. Syntheses of new rare earth complexes with carboxymethylated polysaccharides and evaluation of their in vitro antifungal activities.

    PubMed

    Sun, Xiaobo; Jin, Xiaozhe; Pan, Wei; Wang, Jinping

    2014-11-26

    In the present paper, La, Eu and Yb were selected to represent light, middle and heavy rare earths to form complexes with polysaccharides through chelating coordination of carboxyl groups, which were added into polysaccharide chains by means of carboxymethylation. Their antifungal activities against plant pathogenic fungi were evaluated using growth rate method. These rare earth complexes exhibited various antifungal activities against the tested fungi, depending on rare earth elements, polysaccharide types and fungal species. Among these three metal elements (i.e. La, Eu and Yb), Yb formed the complexes with the most effective antifungal properties. Furthermore, the results showed that ligands of carboxymethylated polysaccharides played a key role in promoting cytotoxicity of the rare earth complexes. Carboxymethylated Ganoderma applanatum polysaccharide (CGAP) was found to be the most effective ligand to form complexes with antifungal activities, followed by carboxymethylated lentinan (CLNT) and carboxymethylated Momordica charantia polysaccharide (CMCP).

  20. [Broad excitation band alkaline-earth silicate luminescent materials activated by rare earth and its applications].

    PubMed

    Xia, Wei; Lei, Ming-Kai; Luo, Xi-Xian; Xiao, Zhi-Guo

    2008-01-01

    Series of novel broad excitation band phosphors M2 MgSis O7 : Eu, Dy(M = Ca, Sr) were prepared by a high temperature solid-state reaction method. The crystal structure of compound was characterized. And the effects of part substitution of alkaline-earth on crystal structure, photoluminescence spectra and luminescence properties were also investigated. It is found that the excitation band of silicate luminescent materials extend to visible region and they exhibit yellow, green and blue long after-glow luminescence after excited by ultraviolet or visible light. Ca MgSi O7 : Eu, Dy luminescent materials can be excited effectively under the 450-480 nm range and exhibit a strong emission at 536 nm, nicely combining with blue light emitted by InGaN chips to produce white light. This promises the silicate luminescent materials a potential yellow phosphor for white LED.

  1. Alaska's rare earth deposits and resource potential

    USGS Publications Warehouse

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

    2012-01-01

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

  2. Synthesis and anticarcinogenic activity of 5-fluorouracil-1-acetic acid complexes with rare earths

    SciTech Connect

    Wang Liu-Fang; Yang Zheng-Yin; Peng Zhou-Ren ); Cheng Guo-Quan; Guo Hong-Ying; Sun Al-Li ); Wang QI; He Feng Ying )

    1993-01-01

    Thirteen new solid complexes of 5-fluorouracilacetic acid (FAA) with rare earth metals (RE) have been synthesized. Elemental analysis, IR, UV spectra, TG-DTA, conductance measurements and [sup 1]H NMR spectra have been used to characterise them. The general formula of the complexes is Ln(FAA)[sub 3][center dot]2H[sub 2]O (Ln = La [yields] Yb, Pm not included). The anticarcinogenic activity of La(FAA)[sub 3][center dot]2H[sub 2]O was tested. The results obtained showed that the survival period of mice which had been transplanted with ascites carcinoma (HepA) and then treated with the La complex can be prolonged to 235% of the control but the ligand alone showed little anticarcinogenic activity. Some 42% of EC cancer cell growth can be inhibited by the La complex. the LD[sub 50] is 500 mg kg[sup [minus

  3. China's rare-earth industry

    USGS Publications Warehouse

    Tse, Pui-Kwan

    2011-01-01

    Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

  4. Cerium-activated rare-earth orthophosphate and double-phosphate scintillators for x-and gamma-ray detection

    SciTech Connect

    Boatner, Lynn A; Keefer, Lara A; Farmer, James Matthew; Wisniewski, D.; Wojtowicz, A. J.

    2004-01-01

    When activated with an appropriate rare-earth ion (e.g., Ce or Nd), rare-earth orthophosphates of the form REPO4 (where RE = a rare-earth cation) and alkali rare-earth double phosphates of the form A{sub 3}RE(PO{sub 4}){sub 2} (where A = K, Rb, or Cs) are characterized by light yields and decay times that make these materials of interest for radiation-detection applications. Crystals of the compound Rb{sub 3}Lu(PO{sub 4}){sub 2} when activated with {approx}0.1 mol % Ce exhibit a light yield that is {approx}250% that of BGO with a decay time on the order of {approx}40 nsec. The cerium-activated rare-earth orthophosphate LuPO{sub 4}:Ce is also characterized by a high light yield and a relatively fast decay time of {approx}25 nsec. Additionally, the rare-earth orthophosphates are extremely chemically, physically, and thermally durable hosts that recover easily from radiation damage effects. The properties of the rare-earth orthophosphates and double phosphates that pertain to their use as X- and gamma-ray detectors are reviewed. This review includes information related to the use of Nd-doped LuPO{sub 4} as a scintillator with a sufficiently energetic, short-wavelength output ({lambda} = 90 nm) so that it can be used in conjunction with appropriately activated proportional counters. Information is presented on the details of the synthesis, structure, and luminescence properties of lanthanide double phosphates that, when activated with cerium, are efficient scintillators with output wavelengths that are sufficiently long to be well matched to the response of silicon photodiode detectors.

  5. Phase stable rare earth garnets

    DOEpatents

    Kuntz, Joshua D.; Cherepy, Nerine J.; Roberts, Jeffery J.; Payne, Stephen A.

    2013-06-11

    A transparent ceramic according to one embodiment includes a rare earth garnet comprising A.sub.hB.sub.iC.sub.jO.sub.12, where h is 3.+-.10%, i is 2.+-.10%, and j is 3.+-.10%. A includes a rare earth element or a mixture of rare earth elements, B includes at least one of aluminum, gallium and scandium, and C includes at least one of aluminum, gallium and scandium, where A is at a dodecahedral site of the garnet, B is at an octahedral site of the garnet, and C is at a tetrahedral site of the garnet. In one embodiment, the rare earth garment has scintillation properties. A radiation detector in one embodiment includes a transparent ceramic as described above and a photo detector optically coupled to the rare earth garnet.

  6. The Not-So-Rare Earths.

    ERIC Educational Resources Information Center

    Muecke, Gunter K.; Moller, Peter

    1988-01-01

    Describes the characteristics of rare earth elements. Details the physical chemistry of rare earths. Reviews the history of rare earth chemistry and mineralogy. Discusses the mineralogy and crystallography of the formation of rare earth laden minerals found in the earth's crust. Characterizes the geologic history of rare earth elements. (CW)

  7. Analysis of low levels of rare earths by radiochemical neutron activation analysis

    USGS Publications Warehouse

    Wandless, G.A.; Morgan, J.W.

    1985-01-01

    A procedure for the radiochemical neutron-activation analysis for the rare earth elements (REE) involves the separation of the REE as a group by rapid ion-exchange methods and determination of yields by reactivation or by energy dispersive X-ray fluorescence (EDXRF) spectrometry. The U. S. Geological Survey (USGS) standard rocks, BCR-1 and AGV-1, were analyzed to determine the precision and accuracy of the method. We found that the precision was ??5-10% on the basis of replicate analysis and that, in general the accuracy was within ??5% of accepted values for most REE. Data for USGS standard rocks BIR-1 (Icelandic basalt) and DNC-1 (North Carolina diabase) are also presented. ?? 1985 Akade??miai Kiado??.

  8. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration

    PubMed Central

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency. PMID:26819083

  9. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration

    NASA Astrophysics Data System (ADS)

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-01

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.

  10. Innovative Application of Mechanical Activation for Rare Earth Elements Recovering: Process Optimization and Mechanism Exploration.

    PubMed

    Tan, Quanyin; Deng, Chao; Li, Jinhui

    2016-01-28

    With the rapidly expanding use of fluorescent lamps (FLs) and increasing interest in conservation and sustainable utilization of critical metals such as rare earth elements (REEs), the recovering of REEs from phosphors in waste FLs is becoming a critical environmental and economic issue. To effectively recycle REEs with metallurgical methods, mechanical activation by ball milling was introduced to pretreat the waste phosphors. This current study put the emphasis on the mechanical activation and leaching processes for REEs, and explored the feasibility of the method from both theoretical and practical standpoints. Results showed physicochemical changes of structural destruction and particle size reduction after mechanical activation, leading to the easy dissolution of REEs in the activated samples. Under optimal conditions, dissolution yields of 89.4%, 93.1% and 94.6% for Tb, Eu and Y, respectively, were achieved from activated waste phosphors using hydrochloric acid as the dissolution agent. The shrinking core model proved to be the most applicable for the leaching procedure, with an apparent activation energy of 10.96 ± 2.79 kJ/mol. This novel process indicates that mechanical activation is an efficient method for recovering REEs from waste phosphors, and it has promising potential for REE recovery with low cost and high efficiency.

  11. Rare Earth Optical Temperature Sensor

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

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

    PubMed

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

    2015-02-09

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

  13. Synthesis, characterization, antioxidative and antitumor activities of solid quercetin rare earth(III) complexes.

    PubMed

    Zhou, J; Wang, L F; Wang, J Y; Tang, N

    2001-01-01

    Eight rare earth metal(II) complexes with quercetin ML3 x 6H2O [L=quercetin (3-OH group deprotonated); M = La, Nd, Eu, Gd, Tb, Dy, Tm and Y] have been synthesized and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR, UV, 1HNMR and fluorescence spectra techniques as well as cyclic voltammetry. The quercetin:metal stoichiometry and the equilibrium stability constant for metal binding to quercetin have been determined. The antioxidative and antitumor activities of quercetin x 2H2O and the complexes were tested by both the MTT and SRB methods. The results show that the suppression ratio of the complexes against the tested tumour cells are superior to quercetin x 2H2O. The property of LaL3 x 6H2O reacting with calf thymus DNA was studied by fluorescence methods. The La-complex binding to DNA has been determined by fluorescence titration in 0.05 M Tris-HCl, 0.5 M NaCl buffer (pH 7.0). The results indicate that the interaction of the complex with DNA is very evident.

  14. Tailored spectroscopic and optical properties in rare earth-activated glass-ceramics planar waveguides

    NASA Astrophysics Data System (ADS)

    Ristic, Davor; Van Tran, Thi Thanh; Dieudonné, Belto; Cristina, Armellini; Berneschi, Simone; Chiappini, Andrea; Chiasera, Alessandro; Varas, Stefano; Carpentiero, Alessandro; Mazzola, Maurizio; Nunzi Conti, Gualtiero; Pelli, Stefano; Speranza, Giorgio; Feron, Patrice; Duverger Arfuso, Claire; Cibiel, Gilles; Turrell, Sylvia; Tran Ngoc, Khiem; Boulard, Brigitte; Righini, Giancarlo C.; Ferrari, Maurizio

    2013-03-01

    Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of art the fabrication techniques based on bottom-up and top-down approaches appear to be viable although a specific effort is required to achieve the necessary reliability and reproducibility of the preparation protocols. In particular, the dependence of the final product on the specific parent glass and on the employed synthesis still remain an important task of the research in material science. Glass-ceramic waveguides overcome some of the efficiency problems experienced with conventional waveguides. These two-phase materials are composed of nanocrystals embedded in an amorphous matrix. The respective volume fractions of the crystalline and amorphous phases determine the properties of the glass ceramic. They also represent a valid alternative to widely used glass hosts such as silica as an effective optical medium for light propagation and luminescence enhancement. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including optical amplifiers, monolithic waveguide laser, novel sensors, coating of spherical microresonators, and up and down converters for solar energy exploitation.

  15. Using rare earth element tracers and neutron activation analysis to study rill erosion process.

    PubMed

    Li, Mian; Li, Zhan-bin; Ding, Weng-feng; Liu, Pu-ling; Yao, Wen-yi

    2006-03-01

    Spatially averaged soil erosion data provide little information on the process of rill erosion. The dynamically varied data on the temporal and spatial distributions in the rill erosion process are needed to better understand the erosion process and reveal its innate characteristics. The objectives of this study were to examine the feasibility and effectiveness of rare earth element (REE) tracers and the neutron activation analysis (NAA) method on the study of the rill erosion process and to reveal quantitatively the relationships and characteristics of temporal and spatial distributions of sediment yield in rill erosion. Four REEs were used to study the changeable process of rill erosion at 4 slope positions. Four water inflow rates were applied to a 0.3 x 5 m soil bed at 3 slopes of 10.5%, 15.8% and 21.2% in scouring experiments. All of the runoff was collected in the experiment. Each sample was air-dried and well mixed. Then 20 g of each sample was sieved through 100-mesh and about a 50 mg sample was weighed for analysis of the four elemental compositions by NAA. Results indicate that the REE tracers and NAA method can be used to not only quantitatively determine soil erosion amounts on different slope segments, but also to reveal the changeable process of rill erosion amount. All of the relative errors of the experimental results were less than 25%, which is considered satisfactory on the study of rill erosion process.

  16. Visible light activated photocatalytic behaviour of rare earth modified commercial TiO{sub 2}

    SciTech Connect

    Tobaldi, D.M.; Seabra, M.P.; Labrincha, J.A.

    2014-02-01

    Highlights: • RE gave more surface hydroxyl groups attached to the photocatalyst's surface. • RE gave the modified and fired samples a high specific surface area. • Photocatalytic activity was assessed in gas–solid phase under visible-light exposure. • Thermal treated RE-TiO{sub 2}s showed a superior visible-light photocatalytic activity. • La-TiO{sub 2} was the best performing photocatalyst. - Abstract: A commercial TiO{sub 2} nanopowder, Degussa P25, was modified with several rare earth (RE) elements in order to extend its photocatalytic activity into the visible range. The mixtures were prepared via solid-state reaction of the precursor oxides, and thermally treated at high temperature (900 and 1000 °C), with the aim of investigating the photocatalytic activity of the thermally treated samples. This thermal treatment was chosen for a prospective application as a surface layer in materials that need to be processed at high temperatures. The photocatalytic activity (PCA) of the samples was assessed in gas–solid phase – monitoring the degradation of isopropanol (IPA) – under visible-light irradiation. Results showed that the addition of the REs lanthanum, europium and yttrium to TiO{sub 2} greatly improved its photocatalytic activity, despite the thermal treatment, because of the presence of more surface hydroxyl groups attached to the photocatalyst's surface, together with a higher specific surface area (SSA) of the modified and thermally treated samples, with regard to the unmodified and thermally treated Degussa P25. The samples doped with La, Eu and Y all had excellent PCA under visible-light irradiation, even higher than the untreated Degussa P25 reference sample, despite their thermal treatment at 900 °C, with lanthanum producing the best results (i.e. the La-, Eu- and Y-TiO{sub 2} samples, thermally treated at 900 °C, had, respectively, a PCA equal to 26, 27 and 18 ppm h{sup −1} – in terms of acetone formation – versus 15 ppm h

  17. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

    2001-01-01

    A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

  18. Synthesis and catalytic activity of heterogeneous rare-earth metal catalysts coordinated with multitopic Schiff-base ligands.

    PubMed

    Sun, Yilin; Wu, Guangming; Cen, Dinghai; Chen, Yaofeng; Wang, Limin

    2012-08-28

    Four multitopic Schiff-base ligand precursors were synthesized via condensation of 4,4'-diol-3,3'-diformyl-1,1'-diphenyl or 1,3,5-tris(4-hydroxy-5-formylphenyl)benzene with 2,6-diisopropylaniline or 2,6-dimethylaniline. Amine elimination reactions of Ln[N(SiMe(3))(2)](3) (Ln = La, Nd, Sm or Y) with these multitopic ligand precursors gave ten heterogeneous rare-earth metal catalysts. These heterogeneous rare-earth metal catalysts are active for intramolecular hydroalkoxylation of alkynols, and the catalytic activities are influenced by the ligand and metal ion. The recycling experiment on the most active heterogeneous catalyst showed the catalyst has a good reusability.

  19. Alteration of rare earth element distribution as a result of microbial activity and empirical methane injection

    NASA Astrophysics Data System (ADS)

    Castillo, D. J.; Davies, N. W.; Thurber, A. R.; Haley, B. A.; Colwell, F. S.

    2014-12-01

    As a result of warming, methane is being released into the marine environment in areas that have not historically experienced methane input. While methane is a potent greenhouse gas, microbial oxidation of methane within the sediment greatly limits the role of marine methane sources on atmospheric forcing. However, in these areas of new methane release, consumption of methane prior to its release into the atmosphere is a result of the response of the microbial community to this new input of methane. Further, rare earth elements (REEs) are not currently thought to be involved with microbial activity, but this assumption has not been rigorously tested. Here we test that: (1) microbial communities will rapidly respond to the onset of methane emission, and (2) the microbial response to this methane input will impact the distribution of REEs within the sediment. Undisturbed cores sampled from a tidal flat at Yaquina Bay, OR, were brought back to a lab and injected with anoxic seawater (as a control) or anoxic sea water saturated with methane gas for a total of 2 weeks. Aerobic methanotrophs proliferated over this short time period, becoming an abundant member of the microbial community as identified using fatty acid biomarkers. Excitingly, the experimental injection of methane also shifted the distribution of REEs within the sediment, a trend that appeared to follow the microbial response and that was different from the control cores. Further, the lightest REEs appeared to be used more than the heavier ones, supporting that the REEs are being actively used by the microbes. While we focused on identifying the response of those microbes responsible in methane-cycling, we also identified how the entire microbial community shifts as a result of methane input, and correlating with shifts in REE distribution. Here we have empirically demonstrated the rapid response of methanotrophs to the onset of methane emission and that REE distribution within the sediment is likely

  20. Composition, characteristic and activity of rare earth element-bound polysaccharide from tea.

    PubMed

    Wang, D; Wang, C; Zhao, G; Wei, Z; Tao, Y; Liang, X

    2001-09-01

    The compositions and structural characteristics of rare earth elements-bound polysaccharides from tea (REE-TPS) were studied with the methods of Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Gas Chromatography (GC) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The results show that polysaccharide from tea (TPS) was a sort of glycoprotein and coordinated with Rare Earth Elements (REE) closely. The sugar fraction was composed of Rha, Ara, Xyl, Fuc, Glc, and Gal. There existed almost all natural amino acids with Glx, Asx, and Hyp as the major parts in the protein fraction. The REEs in REE-TPS were mainly composed of La, Ce, and Nd, especially, more than 75% of them was La. The coordination atom of the first coordination shell of La in REE-TPS was oxygen, the coordination number of which was 6, and the average distance between the atoms was 2.52 A. The second shell was formed from sulfur atoms, the coordination number and the average distance were 3 and 2.91 A, respectively. The bio-experiments show that REE-TPS could decrease the content of blood glucose in mice significantly.

  1. Reactivity of functionalized indoles with rare-earth metal amides. Synthesis, characterization and catalytic activity of rare-earth metal complexes incorporating indolyl ligands.

    PubMed

    Feng, Zhijun; Wei, Yun; Zhou, Shuangliu; Zhang, Guangchao; Zhu, Xiancui; Guo, Liping; Wang, Shaowu; Mu, Xiaolong

    2015-12-21

    The reactivity of several functionalized indoles 2-(RNHCH2)C8H5NH (R = C6H5 (1), (t)Bu (2), 2,6-(i)Pr2C6H3 (3)) with rare-earth metal amides is described. Reactions of 1 or 2 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 (RE = Eu, Yb) respectively produced the europium complexes [2-(C6H5N[double bond, length as m-dash]CH)C8H5N]2Eu[N(SiMe3)2] (4) and [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]Eu[N(SiMe3)2]2 (5), and the ytterbium complex [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]2Yb[N(SiMe3)2] (6), containing bidentate anionic indolyl ligands via dehydrogenation of the amine to the imine. In contrast, reactions of the more sterically bulky indole 3 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 afforded complexes [2-(2,6-(i)Pr2C6H3NCH2)C8H5N]RE[N(SiMe3)2](THF)2 (RE = Yb (7), Y (8), Er (9), Dy (10)) with the deprotonated indolyl ligand. While reactions of 3 with yttrium and ytterbium amides in refluxing toluene respectively gave the complexes [2-(2,6-(i)Pr2C6H3N[double bond, length as m-dash]CH)C8H5N]3Y (11) and [2-(2,6-(i)Pr2C6H3N[double bond, length as m-dash]CH)C8H5N]2Yb(II)(THF)2 (12), along with transformation of the amino group to the imino group, and also with a reduction of Yb(3+) to Yb(2+) in the formation of 12. Reactions of 3 with samarium and neodymium amides provided novel dinuclear complexes {[μ-η(5):η(1):η(1)-2-(2,6-(i)Pr2C6H3NCH2)C8H5N]RE[N(SiMe3)2]}2 (RE = Sm (13), Nd (14)) having indolyl ligands in μ-η(5):η(1):η(1) hapticities. The pathway for the transformation of the amino group to the imino group is proposed on the basis of the experimental results. The new complexes displayed excellent activity in the intramolecular hydroamination of aminoalkenes.

  2. Heavy metals and rare earth elements source-sink in some Egyptian cigarettes as determined by neutron activation analysis.

    PubMed

    Nada, A; Abdel-Wahab, M; Sroor, A; Abdel-Haleem, A S; Abdel-Sabour, M F

    1999-07-01

    Heavy metals and rare earth elements in two types of cigarettes were studied. The contents of trace elements were determined by using delayed neutron activation analysis. In the present study 11 elements have been detected in popular and fine brand cigarettes marketed in Egypt. Evaluation of these elements with their potential hazards for smokers is briefly discussed. The material balance (source and sink) for each element was determined. Also the ratio of element recovery to the total amount was assessed.

  3. Rare Earth Garnet Selective Emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  4. Optically active mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complexes. Synthesis, spectroscopy, and effective chiral information transfer.

    PubMed

    Lu, Jitao; Deng, Yanhua; Zhang, Xiaomei; Kobayashi, Nagao; Jiang, Jianzhuang

    2011-03-21

    With the view to creating novel sandwich-type tetrapyrrole rare earth complexes toward potential applications in material science and chiral catalysis, two new optically active mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complexes with both (R)- and (S)-enantiomers [M(2)(Pc)(2)(TCBP)] {TCBP = Meso-tetrakis [3,4-(11,12:13,14-di(1',2'-naphtho)-1,4,7,10,15,18-hexaoxacycloeicosa-2,11,13-triene)-phenyl] porphyrinate; M = Eu (1), Y (2)} have been designed and prepared by treating optically active metal free porphyrin (R)-/(S)-H(2)TCBP with M(Pc)(2) in the presence of corresponding M(acac)(3)·nH(2)O (acac = acetylacetonate) in refluxing 1,2,4-trichlorobenzene (TCB). These novel mixed ring rare earth triple-decker compounds were characterized by a wide range of spectroscopic methods including MS, (1)H NMR, IR, electronic absorption, and magnetic circular-dichroism (MCD) spectroscopic measurements in addition to elemental analysis. Perfect mirror image relationship was observed in the Soret and Q absorption regions in the circular-dichroism (CD) spectra of the (R)- and (S)-enantiomers, indicating the optically active nature of these two mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complexes. This result reveals the effective chiral information transfer from the peripheral chiral binaphthyl units to the porphyrin and phthalocyanine chromophores in the triple-decker molecule because of the intense π-π interaction between porphyrin and phthalocyanine rings. In addition, their electrochemical properties have also been investigated by cyclic voltammetry (CV).

  5. Bioelectrical activity of the central nervous system among populations in a rare earth element area.

    PubMed

    Zhu, W; Xu, S; Shao, P; Zhang, H; Wu, D; Yang, W; Feng, J

    1997-04-01

    Auditory brainstem electric response (ABR) and somatosensory evoked potential (SEP) of 21 subjects (41 ears) among villagers in a rare earth element (REE) area in Gan County, Jiangxi, China, were studied. No difference in ABR between the subjects from the REE area and the control group was noted. However, the conduction detected by SEP from the median nerve to the thalamus (P15) was shortened (P < 0.05), especially to the first-grade primary somatosensory responsive region (S1) (P < 0.01) and the amplitude of S1 decreased (P < 0.05), indicating that REE was difficult to accumulate in the brainstem, but it was susceptible to cerebral cortex, thus causing sub-clinical damage. This condition was confirmed in the animal experiment. It was suggested that the toxicity through long-term intake of small doses of REE might not be negligible, and the hazard of REE environments should be investigated.

  6. Activating the expression of bacterial cryptic genes by rpoB mutations in RNA polymerase or by rare earth elements.

    PubMed

    Ochi, Kozo; Tanaka, Yukinori; Tojo, Shigeo

    2014-02-01

    Since bacteria were found to contain genes encoding enzymes that synthesize a plethora of potential secondary metabolites, interest has grown in the activation of these cryptic pathways. Homologous and heterologous expression of these cryptic secondary metabolite-biosynthetic genes, often "silent" under ordinary laboratory fermentation conditions, may lead to the discovery of novel secondary metabolites. We review current progress on this topic, describing concepts for activating silent genes. We especially focus on genetic manipulation of transcription and translation, as well as the utilization of rare earth elements as a novel method to activate the silent genes. The possible roles of silent genes in bacterial physiology are also discussed.

  7. Rare Earth Optical Temperature Sensor

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Wolford, David S.

    2000-01-01

    A new optical temperature sensor suitable for high temperatures (greater than 1700 K) and harsh environments is introduced. The key component of the sensor is the rare earth material contained at the end of a sensor that is in contact with the sample being measured. The measured narrow wavelength band emission from the rare earth is used to deduce the sample temperature. A simplified relation between the temperature and measured radiation was verified experimentally. The upper temperature limit of the sensor is determined by material limits to be approximately 2000 C. The lower limit, determined by the minimum detectable radiation, is found to be approximately 700 K. At high temperatures 1 K resolution is predicted. Also, millisecond response times are calculated.

  8. Low-temperature SCR of NO with NH3 over activated semi-coke composite-supported rare earth oxides

    NASA Astrophysics Data System (ADS)

    Wang, Jinping; Yan, Zheng; Liu, Lili; Zhang, Yingyi; Zhang, Zuotai; Wang, Xidong

    2014-08-01

    The catalysts with different rare earth oxides (La, Ce, Pr and Nd) loaded onto activated semi-coke (ASC) via hydrothermal method are prepared for the selective catalytic reduction (SCR) of NO with NH3 at low temperature (150-300 °C). It is evidenced that CeO2 loaded catalysts present the best performance, and the optimum loading amount of CeO2 is about 10 wt%. Composite catalysts by doping La, Pr and Nd into CeO2 are prepared to obtain further improved catalytic properties. The SCR mechanism is investigated through various characterizations, including XRD, Raman, XPS and FT-IR, the results of which indicate that the oxygen defect plays an important role in SCR process and the doped rare earth elements effectively serve as promoters to increase the concentration of oxygen vacancies. It is also found that the oxygen vacancies in high concentration are favored for the adsorption of O2 and further oxidation of NO, which facilitates a rapid progressing of the following reduction reactions. The SCR process of NO with NH3 at low temperature over the catalysts of ASC composite-supported rare earth oxides mainly follows the Langmuir-Hinshlwood mechanism.

  9. Rare earth phosphors and phosphor screens

    DOEpatents

    Buchanan, Robert A.; Maple, T. Grant; Sklensky, Alden F.

    1981-01-01

    This invention relates to rare earth phosphor screens for converting image carrying incident radiation to image carrying visible or near-visible radiation and to the rare earth phosphor materials utilized in such screens. The invention further relates to methods for converting image carrying charged particles to image carrying radiation principally in the blue and near-ultraviolet region of the spectrum and to stabilized rare earth phosphors characterized by having a continuous surface layer of the phosphors of the invention. More particularly, the phosphors of the invention are oxychlorides and oxybromides of yttrium, lanthanum and gadolinium activated with trivalent cerium and the conversion screens are of the type illustratively including x-ray conversion screens, image amplifier tube screens, neutron imaging screens, cathode ray tube screens, high energy gamma ray screens, scintillation detector screens and screens for real-time translation of image carrying high energy radiation to image carrying visible or near-visible radiation.

  10. Scarcity of rare earth elements.

    PubMed

    de Boer, M A; Lammertsma, K

    2013-11-01

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

  11. Production method for making rare earth compounds

    DOEpatents

    McCallum, R.W.; Ellis, T.W.; Dennis, K.W.; Hofer, R.J.; Branagan, D.J.

    1997-11-25

    A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g., a transition metal and optional boron), and a carbide-forming element (e.g., a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g., Nd{sub 2}Fe{sub 14}B or LaNi{sub 5}) and a carbide of the carbide-forming element are formed.

  12. Production method for making rare earth compounds

    DOEpatents

    McCallum, R. William; Ellis, Timothy W.; Dennis, Kevin W.; Hofer, Robert J.; Branagan, Daniel J.

    1997-11-25

    A method of making a rare earth compound, such as a earth-transition metal permanent magnet compound, without the need for producing rare earth metal as a process step, comprises carbothermically reacting a rare earth oxide to form a rare earth carbide and heating the rare earth carbide, a compound-forming reactant (e.g. a transition metal and optional boron), and a carbide-forming element (e.g. a refractory metal) that forms a carbide that is more thermodynamically favorable than the rare earth carbide whereby the rare earth compound (e.g. Nd.sub.2 Fe.sub.14 B or LaNi.sub.5) and a carbide of the carbide-forming element are formed.

  13. Rare earths, the lanthanides, yttrium and scandium

    USGS Publications Warehouse

    Hedrick, J.B.

    2006-01-01

    In 2005, rare earths were not mined in the United States. The major supplier, Molycorp, continued to maintain a large stockpile of rare-earth concentrates and compounds. Consumption decreased of refined rare-earth products. The United States remained a major importer and exporter of rare earths in 2005. During the same period, yttrium was not mined or refined in the US. Hence, supply of yttrium compounds for refined yttrium products came from China, France and Japan. Scandium was not also mined. World production was primarily in China, Russia and Ukraine. Demand for rare earths in 2006 is expected to be closely tied to economic conditions in the US.

  14. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  15. Rare earth elements: end use and recyclability

    USGS Publications Warehouse

    Goonan, Thomas G.

    2011-01-01

    Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

  16. Rare Earth Element Mines, Deposits, and Occurrences

    USGS Publications Warehouse

    Orris, Greta J.; Grauch, Richard I.

    2002-01-01

    Data on rare earth (including yttrium) mines, deposits, and occurrences were compiled as part of an effort by the USGS and the University of Arizona Center for Mineral Resources to summarize current knowledge on the supply and demand outlook and related topics for this group of elements. Economic competition and environmental concerns are increasingly constraining the mining and processing of rare earths from the Mountain Pass mine in California. For many years, the deposit at Mountain Pass was the world's dominant source of rare earth elements and the United States was essentially self-sufficient. Starting approximately 10 years ago, the U.S. has become increasingly dependent (> 90 percent of separated rare earths) upon imports from China, now the dominant source of rare earths. A knowledge of the known economic and noneconomic sources of rare earths is basic to evaluating the outlook for rare earth supply and associated issues.

  17. Rare earth complexes with 3-carbaldehyde chromone-(benzoyl) hydrazone: synthesis, characterization, DNA binding studies and antioxidant activity.

    PubMed

    Li, Yong; Yang, Zheng-Yin

    2010-01-01

    A new ligand, 3-carbaldehyde chromone-(benzoyl) hydrazone (L), was prepared by condensation of 3-carbaldehyde chromone with benzoyl hydrazine. Its four rare earth complexes have been prepared and characterized on the basis of elemental analyses, molar conductivities, mass spectra, (1)H NMR spectra, UV-vis spectra, fluorescence studies and IR spectra. The Sm(III) complex exhibits red fluorescence under UV light and the fluorescent properties of Sm(III) complex in solid state and different solutions were investigated. In addition, the DNA binding properties of the ligand and its complexes have been investigated by electronic absorption spectroscopy, fluorescence spectra, ethidium bromide displacement experiments, iodide quenching experiments, salt effect and viscosity measurements. Experimental results suggest that all the compounds can bind to DNA via an intercalation binding mode. Furthermore, the antioxidant activities of the ligand and its complexes were determined by superoxide and hydroxyl radical scavenging methods in vitro. The rare earth complexes were found to possess potent antioxidant activities that are better than those of the ligand alone.

  18. Mineral resource of the month: rare earths

    USGS Publications Warehouse

    Hedrick, James B.

    2004-01-01

    As if classified as a top-secret project, the rare earths have been shrouded in secrecy. The principal ore mineral of the group, bastnäsite, rarely appears in the leading mineralogy texts. The long names of the rare-earth elements and some unusual arrangements of letters, many Scandinavian in origin, may have intimidated even those skilled in phonics. Somewhat obscurely labeled, the rare earths are neither rare nor earths (the historical term for oxides). They are a relatively abundant group of metallic elements that occur in nature as nonmetallic compounds and have hundreds of commercial applications.

  19. A strong magneto-optical activity in rare-earth La{sup 3+} substituted M-type strontium ferrites

    SciTech Connect

    Hu Feng; Liu Xiansong; Zhu Deru; Fernandez-Garcia, Lucia; Suarez, Marta; Luis Menendez, Jose

    2011-06-01

    M-type strontium ferrites with substitution of Sr{sup 2+} by rare-earth La{sup 3+} were prepared by conventional ceramic technology. The structure, magnetic properties, and magneto-optical Kerr activity of Sr{sub 1-x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.05, 0.10, 0.15, 0.20) were investigated by x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and magneto-optical ellipsometry, respectively. X-ray diffraction showed that the samples sintered at 1290 deg. C for 3 h were single M-type hexagonal ferrites. The magnetic properties were remarkably changed due to the valence change of Fe ions induced by the substitution of La ions. Most significantly, an important magneto-optical activity was induced in the La{sup 3+} substituted M-type strontium ferrites around 3 eV.

  20. Rare earths, the lanthanides, yttrium and scandium

    USGS Publications Warehouse

    Bedinger, G.; Bleiwas, D.

    2012-01-01

    In 2011, rare earths were recovered from bastnasite concentrates at the Mountain Pass Mine in California. Consumption of refined rare-earth products decreased in 2011 from 2010. U.S. rare-earth imports originated primarily from China, with lesser amounts from Austria, Estonia, France and Japan. The United States imported all of its demand for yttrium metal and yttrium compounds, with most of it originating from China. Scandium was imported in various forms and processed domestically.

  1. Improved method for preparing rare earth sesquichalcogenides

    DOEpatents

    Takeshita, T.; Beaudry, B.J.; Gschneidner, K.A. Jr.

    1982-04-14

    An improved method for the preparation of high purity rare earth sesquichalcogenides is described. The rare earth, as one or more pieces of the metal, is sealed under a vacuum with a stoichiometric amount of sulfur or selenium and a small amount of iodine into a quartz reaction vessel. The sealed vessel is then heated to above the vaporization temperature of the chalcogen and below the melting temperature of the rare earth metal and maintained until the product has been formed. The iodine is then vaporized off leaving a pure product. The rare earth sulfides and selenides thus formed are useful as semiconductors and as thermoelectric generators. 3 tables.

  2. Recycling of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

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

  3. Ames Lab 101: Rare-Earth Recycling

    ScienceCinema

    Ryan Ott

    2016-07-12

    Recycling keeps paper, plastics, and even jeans out of landfills. Could recycling rare-earth magnets do the same? Perhaps, if the recycling process can be improved. Scientists at the U.S. Department of Energy's Ames Laboratory are working to more effectively remove the neodymium, a rare earth, from the mix of other materials in a magnet.

  4. Ames Lab 101: Rare-Earth Recycling

    SciTech Connect

    Ryan Ott

    2012-09-05

    Recycling keeps paper, plastics, and even jeans out of landfills. Could recycling rare-earth magnets do the same? Perhaps, if the recycling process can be improved. Scientists at the U.S. Department of Energy's Ames Laboratory are working to more effectively remove the neodymium, a rare earth, from the mix of other materials in a magnet.

  5. Ternary rare earth-lanthanide sulfides

    DOEpatents

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

    1987-01-06

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

  6. Rare Earth Metals: Resourcefulness and Recovery

    NASA Astrophysics Data System (ADS)

    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.

  7. Mechanistic study of the hydrodesulfurization of methanethiol over tungsten disulfide; a survey of rare earth sulfides for hydrodesulfurization activity

    SciTech Connect

    Dowd, D.Q.

    1985-06-01

    Hydrodesulfurization is a process whereby sulfur bound in organic compounds is removed as hydrogen sulfide, and is important to the control of sulfur dioxide emissions in the combustion of petroleum and coal fuels. It involves the cleavage of carbon sulfur bonds, and is catalyzed by layered disulfides such as molybdenum and tungsten disulfide. The simplest example is the reaction CH/sub 3/SH + H/sub 2/ ..-->.. CH/sub 4/ + H/sub 2/S. The mechanism of even this protypical reaction is unclear. In an effort to clarify it, the kinetics of methanethiol hydrodesulfurization over tungsten disulfide at low pressures was established, with partial pressures of methanethiol and hydrogen varied over a hundred fold. The kinetic order in each reactant was positive when its partial pressure was low negative when its partial pressure was high. The negative order in hydrogen had not been previously seen. The product gases, methane and hydrogen sulfide, each exhibited negative kinetic orders at high partial pressures, zero kinetic orders at low partial pressures. A dual site Langmuir-Hinshelwood type mechanism, which defines one active site as two adjacent edge sulfur vacancies and the second as a neighboring sulfur atom, describes these results quite well. Seventeen rare earth sulfides were surveyed for catalytic activity toward methanethiol hydrodesulfurization. These sulfides included both stoichiometric and nonstoichiometric compositions and four different morphologies. In general, nonconductors were inactive and conductors were active. This correlation extended to the nonstoichiometric ..gamma..-phase sesquisulfides which exhibit both insulating and conducting properties. 96 refs.

  8. Mechanistic study of the hydrodesulfurization of methanethiol over tungsten disulfide. II. A survey of rare earth sulfides for hydrodesulfurization activity

    SciTech Connect

    Dowd, D.Q.

    1985-01-01

    I. Hydrodesulfurization is a process whereby sulfur bound in organic compounds is removed as hydrogen sulfide, and is important to the control of sulfur dioxide emissions in the combustion of petroleum and coal fuels. It involves the cleavage of carbon sulfur bonds, and is catalyzed by layered disulfides such as molybdenum and tungsten disulfide. The simplest example is the reaction CH/sub 3/SH + H/sub 2/ ..-->.. CH/sub 4/ + H/sub 2/S. The mechanism of even this prototypical reaction is unclear. In an effort to clarify it, the kinetics of methanethiol hydro desulfurization over tungsten disulfide at low pressures was established, with partial pressures of methanethiol and hydrogen varied over a hundred fold. The kinetic order in each reactant was positive when its partial pressure was low, negative when its partial pressure was high. The negative order in hydrogen had not been previously seen. The product gases, methane and hydrogen sulfide, each exhibited negative kinetic orders at high partial pressures, zero kinetic orders at low partial pressures. A dual site Langmuir-Hinshelwood type mechanism, which defines one active site as two adjacent edge sulfur vacancies and the second as a neighboring sulfur atom, describes these results quite well. II. Seventeen rare earth sulfides were surveyed for catalytic activity toward methanethiol hydrodesulfurization. These sulfides included both stoichiometric and nonstoichiometric compositions and four different morphologies. In general, nonconductors were inactive and conductors were active. This correlation extended to the nonstoichiometric ..gamma..-phase sesquisulfides which exhibit both insulating and conducting properties.

  9. Influence of rare earth elements on metabolism and related enzyme activity and isozyme expression in Tetrastigma hemsleyanum cell suspension cultures.

    PubMed

    Xin, Peng; Shuang-Lin, Zhou; Jun-Yao, He; Li, Ding

    2013-04-01

    The effects of rare earth elements (REEs) not only on cell growth and flavonoid accumulation of Tetrastigma hemsleyanum suspension cells but also on the isoenzyme patterns and activities of related enzymes were studied in this paper. There were no significant differences in enhancement of flavonoid accumulation in T. hemsleyanum suspension cells among La(3+), Ce(3+), and Nd(3+). Whereas their inductive effects on cell proliferation varied greatly. The most significant effects were achieved with 100 μM Ce(3+)and Nd(3+). Under treatment over a 25-day culture period, the maximal biomass levels reached 1.92- and 1.74-fold and the total flavonoid contents are 1.45- and 1.49-fold, than that of control, respectively. Catalase, phenylalanine ammonia-lyase (PAL), and peroxidase (POD) activity was activated significantly when the REE concentration range from 0 to 300 μM, whereas no significant changes were found in superoxide dismutase activity. Differences of esterase isozymes under REE treatment only laid in expression level, and there were no specific bands. The expression level of some POD isozymes strengthened with increasing concentration of REEs within the range of 50-200 μM. When REE concentration was higher than 300 μM, the expression of some POD isozymes was inhibited; meanwhile, some other new POD isozymes were induced. Our results also showed REEs did not directly influence PAL activity. So, we speculated that 50-200 μM REEs could activate some of antioxidant enzymes, adjust some isozymes expression, trigger the defense responses of T. hemsleyanum suspension cells, and stimulate flavonoid accumulation by inducing PAL activity.

  10. Condensation and fractionation of rare earths in the solar nebula

    NASA Technical Reports Server (NTRS)

    Davis, A. M.; Grossman, L.

    1979-01-01

    The condensation behavior of the rare earth elements in the solar nebula is calculated on the basis of the most recent thermodynamic data in order to construct a model explaining group II rare earth element patterns in Allende inclusions. Models considered all involve the removal of large fractions of the more refractory heavy rare earth elements in an early condensate, followed by the condensation of the remainder at a lower temperature. It is shown that the model of Boynton (1975) in which one rare earth element component is dissolved nonideally in perovskite according to relative activity coefficients can not reasonably be made to fit the observed group II patterns. A model in which two rare earth components control the patterns and dissolve ideally in perovskite is proposed and shown to be able to account for the 20 patterns by variations of the perovskite removal temperature and the relative proportions of the two components.

  11. Novel Fiber Preforms: Rare Earth Doping.

    DTIC Science & Technology

    1988-01-21

    measurements were made on a Digilab FTS-15B as KBr While there are many complex multicomponent rare pellets from 3800-4(0cm and as low density poivethvene...earth glasses, phosphates hold special interest as binary pellets t50-500cm ). Spectral resolution was 2 cm- cr rare earth glasses of variable composition...SiO- the glasses have compositions in the range x = 0.009 to 0052. w.hich corresponds to 0.9 to 5.2 molo or up to 23 wt% rare earth oxide as determruned

  12. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    ,

    2011-01-01

    The article provides information on rare earth elements, which are group of 17 natural metallic elements. The rare earth elements are scandium, yttrium and lanthanides and classified into light rare earth elements (LREE) and heavy rate earth elements (HREE). The principal ores of the rare earth elements are identified. An overview of China's production of 97 percent of the rare earths in the world is provided. Commercial applications of rare earths are described.

  13. Improved separation of the curcuminoids, syntheses of their rare earth complexes, and studies of potential antiosteoporotic activity.

    PubMed

    Mawani, Yasmin; Orvig, Chris

    2014-03-01

    The first reported homogenous rare earth curcumin (HCurc; ((1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione)) complexes with the formula ML3, where M(3+) is Eu(III), Gd(III) or Lu(III), were synthesized and characterized by mass spectrometry, infrared spectroscopy and, in the case of the lutetium complex, (1)H NMR spectroscopy. Most importantly an improved separation of the three curcuminoids, HCurc, HDMC ((1E,6E)-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) and HBDMC ((1E,6E)-1,7-bis(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) was realized using a combination of normal-phase column and phosphate-impregnated preparative-thin layer chromatographies. The toxicities of the metal curcumin complexes and ligands were investigated in MG-63 cells, an osteoblast-like cell line, for potential activity as antiosteoporotic agents.

  14. Dimeric rare-earth BINOLate complexes: activation of 1,4-benzoquinone through Lewis acid promoted potential shifts.

    PubMed

    Robinson, Jerome R; Booth, Corwin H; Carroll, Patrick J; Walsh, Patrick J; Schelter, Eric J

    2013-05-03

    Reaction of p-benzoquinone (BQ) with a series of rare-earth metal/alkali metal/1,1'-BINOLate (REMB) complexes (RE: La, Ce, Pr, Nd; M: Li) results in the largest recorded shift in reduction potential observed for BQ upon complexation. In the case of cerium, the formation of a 2:1 Ce/BQ complex shifts the two-electron reduction of BQ by greater than or equal to 1.6 V to a more favorable potential. Reactivity investigations were extended to other RE(III) (RE = La, Pr, Nd) complexes where the resulting highly electron-deficient quinone ligands afforded isolation of the first lanthanide quinhydrone-type charge-transfer complexes. The large reduction-potential shift associated with the formation of 2:1 Ce/BQ complexes illustrate the potential of Ce complexes to function both as a Lewis acid and an electron source in redox chemistry and organic-substrate activation.

  15. Rare-earth alkyl complexes supported by formamidinate ligands: synthesis, structure, and catalytic activity for isoprene polymerization.

    PubMed

    Guo, Liping; Zhu, Xiancui; Zhou, Shuangliu; Mu, Xiaolong; Wei, Yun; Wang, Shaowu; Feng, Zhijun; Zhang, Guangchao; Deng, Baojia

    2014-05-14

    A series of rare-earth metal monoalkyl complexes supported by N,N'-di(2,6-dialkylphenyl)formamidinate ligand (L)2RECH2SiMe3·thf [L(1) = HC(N-2,6-Me2C6H3)2, RE = Y (1), L(2) = HC(N-2,6-(i)Pr2C6H3)2, RE = Y (2), Er (3), Dy (4), Sm (5), and Nd (6)] were synthesized by alkyl elimination reaction or by salt metathesis reaction in good yields. All complexes were characterized by elemental analyses, FT-IR spectroscopy and single crystal X-ray diffraction. In combination with [Ph3C][B(C6F5)4] and alkylaluminium, these complexes displayed a good activity towards isoprene polymerization to give polyisoprenes with high molecular weight (M(n) > 10(4)) and narrow molecular distribution (PDI < 2.0). The influence of alkylaluminium, central metal, temperature, sequence of addition of alkylaluminium and [Ph3C][B(C6F5)4] on the polymerization of isoprene was studied. It was interesting to find that addition of the cocatalysts sequence has a great influence on the regioselectivity of the polymerization. High 1,4-regioselectivity polymerizations of isoprene (as high as 98%) were observed when the catalysts were added in the order [RE]/[alkylaluminum]/[borate].

  16. Atmospheric deposition of rare earth elements in Albania studied by the moss biomonitoring technique, neutron activation analysis and GIS technology.

    PubMed

    Allajbeu, Sh; Yushin, N S; Qarri, F; Duliu, O G; Lazo, P; Frontasyeva, M V

    2016-07-01

    Rare earth elements (REEs) are typically conservative elements that are scarcely derived from anthropogenic sources. The mobilization of REEs in the environment requires the monitoring of these elements in environmental matrices, in which they are present at trace level. The determination of 11 REEs in carpet-forming moss species (Hypnum cupressiforme) collected from 44 sampling sites over the whole territory of the country were done by using epithermal neutron activation analysis (ENAA) at IBR-2 fast pulsed reactor in Dubna. This paper is focused on REEs (lanthanides) and Sc. Fe as typical consistent element and Th that appeared good correlations between the elements of lanthanides are included in this paper. Th, Sc, and REEs were never previously determined in the air deposition of Albania. Descriptive statistics were used for data treatment using MINITAB 17 software package. The median values of the elements under investigation were compared with those of the neighboring countries such as Bulgaria, Macedonia, Romania, and Serbia, as well as Norway which is selected as a clean area. Geographical distribution maps of the elements over the sampled territory were constructed using geographic information system (GIS) technology. Geochemical behavior of REEs in moss samples has been studied by using the ternary diagram of Sc-La-Th, Spider diagrams and multivariate analysis. It was revealed that the accumulation of REEs in current mosses is associated with the wind-blowing metal-enriched soils that is pointed out as the main emitting factor of the elements under investigation.

  17. Rare earth elements content in geological samples from eastern desert, Egypt, determined by instrumental neutron activation analysis.

    PubMed

    El-Taher, A

    2010-09-01

    Twenty representative geological samples (tonalite, granodiorite, adamellite, syenogranite, rapakivi syenogranite, alkali feldspar granite and monzogranite) were collected from G. Kattar area in Eastern Desert, Egypt, for analysis by instrumental neutron activation as a sensitive nondestructive analytical tool for the determination of 14 rare earth elements (REEs) and to find out the following: (1) what information could be obtained about the REEs and distribution patterns of REEs in geological samples under investigation, (2) to estimate the accuracy, reproducibility and detection limit of the INAA method in case of the given samples. The samples were properly prepared together with standard reference material and simultaneously irradiated in a neutron flux of 7x10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The gamma spectra were collected by an HPGe detector and the analysis was done by means of a computerized multichannel analyzer. The choice of the nuclear reaction, irradiation and decay times, and of the proper gamma radiation in counting are presented and discussed. The results are found to be in good agreement with certified values.

  18. Ternary rare earth-lanthanide sulfides

    DOEpatents

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

    1987-01-06

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

  19. Discrete divalent rare-earth cationic ROP catalysts: ligand-dependent redox behavior and discrepancies with alkaline-earth analogues in a ligand-assisted activated monomer mechanism.

    PubMed

    Liu, Bo; Roisnel, Thierry; Maron, Laurent; Carpentier, Jean-François; Sarazin, Yann

    2013-03-18

    The first solvent-free cationic complexes of the divalent rare-earth metals, [{RO}RE(II) ](+) [A](-) (RE(II) =Yb(II) , 1; Eu(II) , 2) and [{LO}RE(II) ](+) [A](-) ([A](-) =[H2 N{B(C6 F5 )3 }2 ](-) ; RE(II) =Yb(II) , 3; Eu(II) , 4), have been prepared by using highly chelating monoanionic aminoether-fluoroalkoxide ({RO}(-) ) and aminoether-phenolate ({LO}(-) ) ligands. Complexes 1 and 2 are structurally related to their alkaline-earth analogues [{RO}AE](+) [A](-) (AE=Ca, 5; Sr, 6). Yet, the two families behave very differently during catalysis of the ring-opening polymerization (ROP) of L-lactide (L-LA) and trimethylene carbonate (TMC) performed under immortal conditions with excess BnOH as an exogenous chain-transfer agent. The ligand was found to strongly influence the behavior of the RE(II) complexes during ROP catalysis. The fluoroalkoxide RE(II) catalysts 1 and 2 are not oxidized under ROP conditions, and compare very favorably with their Ca and Sr congeners 5 and 6 in terms of activity (turnover frequency (TOF) in the range 200-400 molL-LA (molEu  h(-1) )) and control over the parameters during the immortal ROP of L-LA (Mn,theor ≈Mn,SEC , Mw /Mn <1.05). The Eu(II) -phenolate 4 provided one of the most effective ROP cationic systems known to date for L-LA polymerization, exhibiting high activity (TOF up to 1 880 molL-LA ⋅(molEu  h)(-1) ) and good control (Mw /Mn =1.05). By contrast, upon addition of L-LA the Yb(II) -phenolate 3 immediately oxidizes to inactive RE(III) species. Yet, the cyclic carbonate TMC was rapidly polymerized by combinations of 3 (or even 1) and BnOH, revealing excellent activities (TOF=5000-7000 molTMC ⋅(molEu  h)(-1) ) and unusually high control (Mn,theor ≈Mn,SEC , Mw /Mn <1.09); under identical conditions, the calcium derivative 5 was entirely inert toward TMC. Based on experimental and kinetic data, a new ligand-assisted activated monomer ROP mechanism is suggested, in which the so-called ancillary ligand plays a

  20. Rare earth element scavenging in seawater

    NASA Astrophysics Data System (ADS)

    Byrne, Robert H.; Kim, Ki-Hyun

    1990-10-01

    Examinations of rare earth element (REE) adsorption in seawater, using a variety of surface-types, indicated that, for most surfaces, light rare earth elements (LREEs) are preferentially adsorbed compared to the heavy rare earths (HREEs). Exceptions to this behavior were observed only for silica phases (glass surfaces, acid-cleaned diatomaceous earth, and synthetic SiO 2). The affinity of the rare earths for surfaces can be strongly affected by thin organic coatings. Glass surfaces which acquired an organic coating through immersion in Tampa Bay exhibited adsorptive behavior typical of organic-rich, rather than glass, surfaces. Models of rare earth distributions between seawater and carboxylate-rich surfaces indicate that scavenging processes which involve such surfaces should exhibit a strong dependence on pH and carbonate complexation. Scavenging models involving carboxylate surfaces produce relative REE abundance patterns in good general agreement with observed shale-normalized REE abundances in seawater. Scavenging by carboxylate-rich surfaces should produce HREE enrichments in seawater relative to the LREEs and may produce enrichments of lanthanum relative to its immediate trivalent neighbors. Due to the origin of distribution coefficients as a difference between REE solution complexation (which increases strongly with atomic number) and surface complexation (which apparently also increases with atomic number) the relative solution abundance patterns of the REEs produced by scavenging reactions can be quite complex.

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

    USGS Publications Warehouse

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

    2016-01-01

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

  2. Synthesis, structure, and catalytic activity of novel trinuclear rare-earth metal amido complexes incorporating μ-η5:η1 bonding indolyl and μ3-oxo groups.

    PubMed

    Yang, Song; Zhu, Xiancui; Zhou, Shuangliu; Wang, Shaowu; Feng, Zhijun; Wei, Yun; Miao, Hui; Guo, Liping; Wang, Fenhua; Zhang, Guangchao; Gu, Xiaoxia; Mu, Xiaolong

    2014-02-14

    The reactions of different pyrrolyl-functionalized indoles with rare-earth metal(III) amides [(Me3Si)2N]3RE(III)(μ-Cl)Li(THF)3 (RE = Yb, Er, Dy, Eu, Y) produced different kinds of rare-earth metal amido complexes. Reactions of N-((1H-pyrrol-2-yl)methylene)-2-(1H-indol-3-yl)ethanamine with rare-earth metal amides [(Me3Si)2N]3RE(III)(μ-Cl)Li(THF)3 (RE = Yb, Er, Dy, Eu, Y) in toluene or THF at temperatures of 75-80 °C afforded the novel trinuclear rare-earth metal amido complexes incorporating the indolyl ligand in μ-η(5):η(1) bonding modes and a μ3-O group, which is believed to originate from cleavage of the THF ring based on experimental results. Reactions of 2-(1H-indol-3-yl)-N-((1-methyl-1H-pyrrol-2-yl)methylene)ethanamine with rare-earth metal(III) amides [(Me3Si)2N]3RE(III)(μ-Cl)Li(THF)3 (RE = Yb, Dy) produced mononuclear ytterbium and dysprosium amides having the indolyl ligand in an η(1) bonding fashion. The results indicate that substituents not only have an influence on reactivity, but also have an influence on the bonding of the indolyl ligands with metals. The catalytic activities of the novel lanthanide amido complexes for the hydrophosphonylation of both aromatic and aliphatic aldehydes and ketones were explored. The results indicate that these complexes display a high catalytic activity for the C-P bond formation under mild conditions when using low catalyst loadings (0.1 mol% for aldehydes and ketones). Thus, it provides a potential way to prepare α-hydroxy phosphonates.

  3. Rare earth elements and permanent magnets (invited)

    NASA Astrophysics Data System (ADS)

    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.

  4. Replacing the Rare Earth Intellectual Capital

    SciTech Connect

    Gschneidner, Jr., Karl

    2011-04-01

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

  5. What about the rare-earth elements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is insufficient understanding of the nutritional physiology of pecan trees and orchards; thus, affecting nutmeat yield and quality, disease resistance and alternate bearing. An analysis of the rare-earth element composition of pecan and related hickory cousins found that they hyperaccumulate ...

  6. Syntheses, characterization and biological activities of rare earth metal complexes with curcumin and 1,10-phenanthroline-5,6-dione.

    PubMed

    Song, Yu-Min; Xu, Jun-Peng; Ding, Lan; Hou, Qian; Liu, Jing-Wang; Zhu, Zao-Long

    2009-03-01

    Three new solid complexes have been synthesized by the reaction of rare earth(III) nitrate with the first ligand curcumin (HL) and the second ligand 1,10-phenanthroline-5,6-dione (L') in alcohol solution (pH=6.5-7.0). The composition of the complexes has been characterized by elemental analysis, molar conductivity, thermogravimetric analysis, IR, UV-vis methods. The results reveal that beta-diketone group of the first ligand to coordinates with rare earth ions in bidentate mode after deprotonated. But the second ligand uses its two N atoms coordinates with rare earth ions in bidentate mode. The general formula of the complexes is REL(3)L' (RE=Sm, Eu, Dy). The results of antibacterial activity indicated that the complexes have excellent antibacterial ability for the testing bacterium than that of curcumin. The result of agarose gel electrophoresis suggested that the complex of SmL(3)L' can cleave the plasmid DNA at physiological pH and temperature. And it was found that the cleavage process of plasmid DNA was sensitive to pH, however, adding radical scavengers almost had no effect on the DNA cleavage reaction, therefore, the cleavage of DNA by SmL(3)L' does not produce diffusible hydroxyl radicals via the Fenton reaction.

  7. Rare-earth oxide nanostructures: rules of rare-earth nitrate thermolysis in octadecylamine.

    PubMed

    Wang, Dingsheng; Wang, Zhongying; Zhao, Peng; Zheng, Wen; Peng, Qing; Liu, Liqin; Chen, Xueyuan; Li, Yadong

    2010-04-01

    The decomposed regularity of rare-earth nitrates in octadecylamine (ODA) is discussed. The experimental results show that these nitrates can be divided into four types. For rare-earth nitrates with larger RE(3+) ions (RE=rare earth, La, Pr, Nd, Sm, Eu, Gd), the decomposed products exhibited platelike nanostructures. For those with smaller RE(3+) ions (RE=Y, Dy, Ho, Er, Tm, Yb), the decomposed products exhibited beltlike nanostructures. For terbium nitrate with a middle RE(3+) ion, the decomposed product exhibited a rodlike nanostructure. The corresponding rare-earth oxides, with the same morphologies as their precursors, could be obtained when these decomposed products were calcined. For cerium nitrate, which showed the greatest differences, flowerlike cerium oxide could be obtained directly from decomposition of the nitrate without further calcination. This regularity is explained on the basis of the lanthanide contraction. Owing to their differences in electron configuration, ionic radius, and crystal structure, such a nitrate family therefore shows different thermolysis properties. In addition, the potential application of these as-obtained rare-earth oxides as catalysts and luminescent materials was investigated. The advantages of this method for rare-earth oxides includes simplicity, high yield, low cost, and ease of scale-up, which are of great importance for their industrial applications.

  8. Precise rare earth analysis of geological materials

    SciTech Connect

    Laul, J.C.; Wogman, N.A.

    1982-01-01

    Rare earth element (REE) concentrations are very informative in revealing chemical fractionation processs in geological systems. The REE's (La-Lu) behavior is characteristic of various primary and secondary minerals which comprise a rock. The REE's contents and their patterns provide a strong fingerprint in distinguishing among various rock types and in understanding the partial melting and/or fractional crystallization of the source region. The REE contents in geological materials are usually at trace levels. To measure all the REE at such levels, radiochemical neutron activation analysis (RNAA) has been used with a REE group separation scheme. To maximize detection sensitivites for individual REE, selective ..gamma..-ray/x-ray measurements have been made using normal Ge(Li) and low-energy photon detectors (LEPD), and Ge(Li)-NaI(Tl) coincidence-noncoincidence spectrometer systems. Using these detection methods an individual REE can be measured at or below the ppB levels; chemical yields of the REE are determined by reactivation.

  9. Systematic variation of rare earths in monazite

    USGS Publications Warehouse

    Murata, K.J.; Rose, H.J.; Carron, M.K.

    1953-01-01

    Ten monazites from widely scattered localities have been analyzed for La, Ce, Pr, Nd, Sm, Gd, Y and Th by means of a combined chemical and emission spectrographic method. The analytical results, calculated to atomic percent of total rare earths (thorium excluded), show a considerable variation in the proportions of every element except praseodymium, which is relatively constant. The general variation trends of the elements may be calculated by assuming that the monazites represent different stages in a fractional precipitation process, and by assuming that there is a gradational increase in the precipitability of rare earth elements with decreasing ionic radius. Fractional precipitation brings about an increase in lanthanum and cerium, little change in praseodymium, and a decrease in neodymium, samarium, gadolinium, and yttrium. Deviations from the calculated lines of variation consist of a simultaneous, abnormal increase or decrease in the proportions of cerium, praseodymium, and neodymium with antipathetic decrease or increase in the proportions of the other elements. These deviations are ascribed to abnormally high or low temperatures that affect the precipitability of the central trio of elements (Ce, Pr, Nd) relatively more than that of the other elements. The following semiquantitative rules have been found useful in describing the composition of rare earths from monazite: 1. 1. The sum of lanthanum and neodymium is very nearly a constant at 42 ?? 2 atomic percent. 2. 2. Praseodymium is very nearly constant at 5 ?? 1 atomic percent. 3. 3. The sum of Ce, Sm, Gd, and Y is very nearly a constant at 53 ?? 3 atomic percent. No correlation could be established between the content of Th and that of any of the rare earth elements. ?? 1953.

  10. SEPARATION OF RARE EARTHS BY SOLVENT EXTRACTION

    DOEpatents

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

    1960-10-11

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

  11. Novel Fiber Preforms: Rare Earth Doping.

    DTIC Science & Technology

    1987-03-31

    proposed by the group at Southampton, and future experiments with axial laser heating of terbium metal are planned. As noted, much of the effort during...been doped with terbium , in our learning to control the doping concentration, we have observed bands of undesired microcrystailinity in some terbium ...preforms with terbium (not yet pulled into fibers), and rare earth glasses formed by sol-gel tech- niques. Future efforts will be to prepare fibers

  12. Recycling of rare earth metals from rare earth-transition metal alloy scrap by liquid metal extraction

    DOEpatents

    Ellis, T.W.; Schmidt, F.A.

    1995-08-01

    A method is described for treating rare earth metal-bearing scrap, waste or other material (e.g. Nd--Fe--B or Dy--Tb--Fe scrap) to recover the rare earth metal comprising melting the rare earth metal-bearing material, melting a Group IIA metal extractant, such as Mg, Ca, or Ba, in which the rare earth is soluble in the molten state, and contacting the melted material and melted extractant at a temperature and for a time effective to extract the rare earth from the melted material into the melted extractant. The rare earth metal is separated from the extractant metal by vacuum sublimation or distillation. 2 figs.

  13. Recycling of rare earth metals from rare earth-transition metal alloy scrap by liquid metal extraction

    DOEpatents

    Ellis, Timothy W.; Schmidt, Frederick A.

    1995-08-01

    Method of treating rare earth metal-bearing scrap, waste or other material (e.g. Nd--Fe--B or Dy--Tb--Fe scrap) to recover the rare earth metal comprising melting the rare earth metal-bearing material, melting a Group IIA metal extractant, such as Mg, Ca, or Ba, in which the rare earth is soluble in the molten state, and contacting the melted material and melted extractant at a temperature and for a time effective to extract the rare earth from the melted material into the melted extractant. The rare earth metal is separated from the extractant metal by vacuum sublimation or distillation.

  14. Anthropogenic Cycles of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    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

  15. Rare earth metal trifluoromethanesulfonates catalyzed benzyl-etherification.

    PubMed

    Kawada, Atsushi; Yasuda, Kayo; Abe, Hitoshi; Harayama, Takashi

    2002-03-01

    Rare earth metal trifluoromethanesulfonates [rare earth metal triflate, RE(OTf)3] were found to be efficient catalyst for benzyl-etherification. In the presence of a catalytic amount of RE(OTf)3, condensation of benzyl alcohols and aliphatic alcohols proceeded smoothly to afford the benzyl ethers. The condensation between benzyl alcohols and thiols also proceeded, and thio ethers were obtained in good yield. In these reactions, RE(OTf)3 could be recovered easily after the reactions were completed and could be reused without loss of activity.

  16. Trace metal and rare earth content of black precipitation events

    SciTech Connect

    Landsberger, S. . Dept. of Nuclear Engineering); Davies, T.D. . School of Environmental Sciences); Tranter, M. )

    1990-01-01

    The authors have used the techniques of non-destructive neutron activation analysis to determine trace metal and rare earth content of black precipitation events occurring in the Cairngorm Mountains in remote areas of Scotland. Thirty-one elements were determined in the particulate matter of snowpack cores that were sliced into sections. An additional analysis was performed for a black acidic snow event. Based on these results and on wind trajectories, increased loadings of many of the heavy metals and rare earth elements appeared to have originated from central Europe. Enrichment factor calculations show anthropogenic emissions for indium, arsenic, zinc, and selenium.

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

    DOEpatents

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

    2006-04-04

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

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

    DOEpatents

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

    2004-07-13

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

  19. 40 CFR 721.6005 - Rare earth phosphate (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Rare earth phosphate (generic). 721... Substances § 721.6005 Rare earth phosphate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as rare earth phophate (PMNs...

  20. 40 CFR 721.6005 - Rare earth phosphate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Rare earth phosphate (generic). 721... Substances § 721.6005 Rare earth phosphate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as rare earth phophate (PMNs...

  1. 40 CFR 721.6005 - Rare earth phosphate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Rare earth phosphate (generic). 721... Substances § 721.6005 Rare earth phosphate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as rare earth phophate (PMNs...

  2. 40 CFR 721.6005 - Rare earth phosphate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Rare earth phosphate (generic). 721... Substances § 721.6005 Rare earth phosphate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as rare earth phophate (PMNs...

  3. 40 CFR 721.6005 - Rare earth phosphate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Rare earth phosphate (generic). 721... Substances § 721.6005 Rare earth phosphate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as rare earth phophate (PMNs...

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

    DOEpatents

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

    2013-04-16

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

  5. Raman Investigations of Rare-Earth Orthovanadates

    SciTech Connect

    Santos, C. C.; Silva, E. N.; Ayala, A. P.; Guedes, I.; Pizani, P. S.; Loong, C. K.; Boatner, Lynn A

    2007-01-01

    Polarized Raman spectroscopy has been used to obtain the room-temperature phonon spectra of the series of rare earth orthovanadate single crystals: SmVO4, HoVO4, YbVO4 and LuVO4. The observed Raman frequencies follow the overall mode distribution expected for RVO4 compounds with the tetragonal zircon structure. The variation of the mode frequency with atomic number across the lanthanide orthovanadate series was investigated, and the trend exhibited by the internal modes was explained by considering the force constants of VO4 tetrahedron.

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

    SciTech Connect

    2012-01-01

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

  7. Note: Portable rare-earth element analyzer using pyroelectric crystal

    SciTech Connect

    Imashuku, Susumu Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun

    2013-12-15

    We report a portable rare-earth element analyzer with a palm-top size chamber including the electron source of a pyroelectric crystal and the sample stage utilizing cathodoluminescence (CL) phenomenon. The portable rare-earth element analyzer utilizing CL phenomenon is the smallest reported so far. The portable rare-earth element analyzer detected the rare-earth elements Dy, Tb, Er, and Sm of ppm order in zircon, which were not detected by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. We also performed an elemental mapping of rare-earth elements by capturing a CL image using CCD camera.

  8. Characterization of a rare earth oxide obtained from xenotime mineral

    SciTech Connect

    Vernilli, Fernando . E-mail: fernando.vernilli@demar.faenquil.br; Camargo Vernilli, Daniela; Ferreira, Bento; Silva, Gilbert

    2007-01-15

    This paper reports on the characterization of a rare earth oxide obtained by hydrometallurgy of the mineral xenotime, an yttrium phosphate containing other rare earths, and comparison with mixtures of rare earth oxides prepared in different ways. The results indicated that hydrometallurgy from xenotime yielded a solid solution of the rare earth oxides. However, when the pure rare earth oxides were simply mixed physically then heat-treated at 1000 deg. C, a similar solid solution was not obtained. On the other hand, when the mixtures were prepared using a co-precipitation process, subsequent heat treatment did produce oxide solid solutions similar to that produced by hydrometallurgy of xenotime.

  9. Reflectives: Phosphors and lasers - shedding light on rare earths

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    The first powder electroluminescent phosphor was introduced in 1936. Today, phosphors, particularly those made of high-purity rare earths, have found their way into a variety of products: industrial, commercial, and consumer, alike. The fluorescent lamp industry which remains the leading market for the use of high-purity rare earths, lit the way for the future of rare earths in the optical, x-ray, and display screen applications. Light combined with rare earth materials is also a successful recipe for reflectivity needed in filtering applications such as optics, lasers, and conductors. This article discusses the applications and markets for phosphors and rare earths.

  10. Rare-earth metal complexes having an unusual indolyl-1,2-dianion through C-H activation with a novel η1:(μ2-η1:η1) bonding with metals.

    PubMed

    Zhu, Xiancui; Zhou, Shuangliu; Wang, Shaowu; Wei, Yun; Zhang, Lijun; Wang, Fenhua; Wang, Shaoyin; Feng, Zhijun

    2012-12-21

    Studies on the reactions of 3-(tert-butyliminomethine)indole or 3-(tert-butylaminomethylene)indole with rare-earth metal amides [(Me(3)Si)(2)N](3)RE(III)(μ-Cl)Li(THF)(3) (RE = Y, Yb) led to the discovery of different reactivity patterns with isolation of novel rare-earth metal complexes having a unique indolyl-1,2-dianion in a novel η(1):(μ(2)-η(1):η(1)) bonding mode through C-H activation.

  11. Atomic Transition Probabilities for Rare Earths

    NASA Astrophysics Data System (ADS)

    Curry, J. J.; Anderson, Heidi M.; den Hartog, E. A.; Wickliffe, M. E.; Lawler, J. E.

    1996-10-01

    Accurate absolute atomic transition probabilities for selected neutral and singly ionized rare earth elements including Tm, Dy, and Ho are being measured. The increasing use of rare earths in high intensity discharge lamps provides motivation; the data are needed for diagnosing and modeling the lamps. Radiative lifetimes, measured using time resolved laser induced fluorescence (LIF), are combined with branching fractions, measured using a large Fourier transform spectrometer (FTS), to determine accurate absolute atomic transition probabilities. More than 15,000 LIF decay curves from Tm and Dy atoms and ions in slow beams have been recorded and analyzed. Radiative lifetimes for 298 levels of TmI and TmII and for 450 levels of DyI and DyII are determined. Branching fractions are extracted from spectra recorded using the 1.0 m FTS at the National Solar Observatory. Branching fractions and absolute transition probabilities for 500 of the strongest TmI and TmII lines are complete. Representative lifetime and branching fraction data will be presented and discussed. Supported by Osram Sylvania Inc. and the NSF.

  12. A COMPARISON OF FAR INFRARED AND RAMAN SPECTRA OF SOME RARE EARTH GARNET SINGLE CRYSTALS,

    DTIC Science & Technology

    RARE EARTH COMPOUNDS, *INFRARED SPECTRA), (*GARNET, RARE EARTH COMPOUNDS), (* RAMAN SPECTROSCOPY, RARE EARTH COMPOUNDS), SINGLE CRYSTALS, ALUMINATES...PHONONS, YTTRIUM COMPOUNDS, YTTERBIUM COMPOUNDS, TERBIUM COMPOUNDS, DYSPROSIUM COMPOUNDS, CANADA

  13. Distributions of rare earths and heavy metals in field-grown maize after application of rare earth-containing fertilizer.

    PubMed

    Xu, Xingkai; Zhu, Wangzhao; Wang, Zijian; Witkamp, Geert-Jan

    2002-07-03

    Rare earths are widely applied in Chinese agriculture to improve crop nutrition through the use of fertilizers, yet little is known of their accumulation in field-grown crops. We have studied the distribution of 16 rare earths (Sc, Y and 14 lanthanide elements) in field-grown maize and the concentration of heavy metals in the grains after application of rare earth-containing fertilizer. When maize entered the vigorous vegetation growth stage (e.g. early stem-elongation stage), rare earth-containing fertilizer was applied to the soil with irrigation water. At 10 days after application of the rare earths, significantly dose-dependent accumulative effects of individual rare earth concentrations in the roots and the plant tops of maize were observed, with the exception of Sc and Lu. At the level of 2 kg rare earths ha(-1), accumulative concentrations of most light rare earths (e.g. La, Ce, Pr and Nd) and Gd in the plant tops were much larger than those in the control. Concentrations of individual rare earths in a field-grown maize after application of rare earths decreased in the order of root>leaf>stem>grain. During the maize growth period, selective accumulation of individual rare earths (e.g. La, Ce) in the roots seemed to be in dynamic equilibrium, and the distribution of these elements in the plant tops was variable. At a dosage of less than 10 kg rare earths ha(-1), no apparent accumulative concentrations of individual rare earths appeared in the maize grains. Under the experimental conditions, application of rare earth-containing fertilizer did not induce an increase in the concentrations of heavy metals in the grains. We conclude that the present dosage of rare earths (<0.23 kg ha(-1) year(-1)) currently applied in China can hardly affect the safety of maize grains in arable soil, even over a long period.

  14. Rare Earth Ion Mediated Fluorescence Accumulation on a Single Microbead: An Ultrasensitive Strategy for the Detection of Protein Kinase Activity at the Single-Cell Level.

    PubMed

    Zhang, Xiaobo; Liu, Chenghui; Wang, Honghong; Wang, Hui; Li, Zhengping

    2015-12-07

    A single microbead-based fluorescence imaging (SBFI) strategy that enables detection of protein kinase activity from single cell lysates is reported. We systematically investigated the ability of various rare earth (RE) ions, immobilized on the microbead, for specific capturing of kinase-induced phosphopeptides, and Dy(3+) was found to be the most prominent one. Through the efficient concentration of kinase-induced fluorescent phosphopeptides on a Dy(3+) -functionalized single microbead, kinase activity can be detected and quantified by reading the fluorescence on the microbead with a confocal fluorescence microscope. Owing to the extremely specific recognition of Dy(3+) towards phosphopeptides and the highly-concentrated fluorescence accumulation on only one microbead, ultrahigh sensitivity has been achieved for the SBFI strategy which allows direct kinase analysis at the single-cell level.

  15. Rare Earth Elements in Global Aqueous Media

    NASA Astrophysics Data System (ADS)

    Noack, C.; Karamalidis, A.; Dzombak, D. A.

    2012-12-01

    We are examining the occurrence and abundance of rare earth elements (REE) associated with produced waters from shale gas development, and factors controlling aqueous REE concentrations in geochemical environments, to provide information for: (1) potential recovery of REE as a valuable byproduct, and (2) utilization of unique REE signatures as a risk assessment tool. REE include the lanthanide series of elements - excluding short-lived, radioactive promethium - and yttrium. These elements are critical to a wide variety of high-tech, energy efficient applications such as phosphors, magnets, and batteries. Escalating costs of REE resulting from divergent supply and demand patterns motivates the first goal. The second goal relates to the search for a reliable, naturally occurring tracer to improve understanding of fluid migration and water-rock interactions during hydraulic fracturing and natural gas recovery. We compiled data from 100 studies of REE occurrence and concentrations in groundwaters, ocean waters, river waters, and lake waters. In the groundwater systems documented, total dissolved REE concentrations ranged over eight orders of magnitude; however the average concentrations across the lanthanides varied by less than two orders of magnitude. This leads to exceptional inter-element correlations, with a median correlation coefficient greater than 0.98, implying potential usefulness of REE ratios for groundwater signatures. Reports describing reactions governing REE solubilization were also investigated. We assembled information about important solution chemistries and performed equilibrium modeling using PHREEQC to examine common hypotheses regarding the factors controlling REE compositions. In particular, effects of pH, Eh, and common complexing ligands were evaluated. Produced and connate waters of the Marcellus shale are well characterized for their major chemical elements. There is a dearth of knowledge, however, regarding the occurrence of REE in

  16. Rare earth elements in river waters

    NASA Technical Reports Server (NTRS)

    Goldstein, Steven J.; Jacobsen, Stein B.

    1988-01-01

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

  17. Rare-earth abundances in chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Evensen, N. M.; Hamilton, P. J.; Onions, R. K.

    1978-01-01

    Fifteen chondrites, including eight carbonaceous chondrites, were analyzed for rare earth element abundances by isotope dilution. Examination of REE for a large number of individual chondrites shows that only a small proportion of the analyses have flat unfractionated REE patterns within experimental error. While some of the remaining analyses are consistent with magmatic fractionation, many patterns, in particular those with positive Ce anomalies, can not be explained by known magmatic processes. Elemental abundance anomalies are found in all major chondrite classes. The persistence of anomalies in chondritic materials relatively removed from direct condensational processes implies that anomalous components are resistant to equilibrium or were introduced at a late stage of chondrite formation. Large-scale segregation of gas and condensate is implied, and bulk variations in REE abundances between planetary bodies is possible.

  18. Gyroscopic g factor of rare earth metals

    NASA Astrophysics Data System (ADS)

    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.

  19. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, A.D.; Modine, F.A.; Lauf, R.J.; Alim, M.A.; Mahan, G.D.; Bartkowiak, M.

    1998-12-29

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

  20. Rare earth doped zinc oxide varistors

    DOEpatents

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

    1998-01-01

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

  1. Parity Violation Experiments with Rare Earth Atoms

    NASA Astrophysics Data System (ADS)

    Budker, Dmitry

    1997-10-01

    Since the first suggestions (V. A. Dzuba, V. V. Flambaum, and I. B. Khriplovich, Z. Phys. D1, 243 (1986).), (A. Gongora and P. G. H. Sandars, J. Phys. B 19, L291 (1986).) to search for parity violation in the rare earth atoms, experiments have been carried out by groups in Novosibirsk, Oxford, Hiroshima and Berkeley with Sm, Yb and Dy. The status of these experiments will be reviewed, with some details given on recent Berkeley Dy results ( A.-T. Nguyen, D. Budker, D. DeMille, and M. Zolotorev, Submitted to Phys. Rev. A.). Progress of the Berkeley Yb experiment ( D. DeMille, Phys. Rev. Lett. 74, 4165 (1995).), ( C.J. Bowers, D. Budker, E.D. Commins, D. DeMille, S.J. Freedman, A.-T. Nguyen, S.-Q. Shang, and M. Zolotorev, Phys. Rev. A 53, 3103-9(1996). ) will be described elsewhere at this meeting by C. J. Bowers et al.

  2. Ferritin protein encapsulated photoluminescent rare earth nanoparticle

    NASA Astrophysics Data System (ADS)

    Harada, T.; Yoshimura, H.

    2013-07-01

    Rare earth (yttrium (Y), europium (Eu), and terbium (Tb)) nanoparticles and Eu and Tb doped Y nanoparticles are synthesized in an apoferritin cavity. They exhibit a narrow size distribution and a high stability in an aqueous solution at pH 8.5. Eu and Eu doped Y (Y:Eu) nanoparticles exhibit red photoluminescence (emission peaks: 590 and 614 nm), while Tb and Tb doped Y (Y:Tb) nanoparticles exhibit green photoluminescence (emission peaks: 488, 544, 582, and 618 nm). High-resolution electron microscopy observations reveal that about 5% of the nanoparticles have a lattice structure, while the remaining nanoparticles are amorphous. Electron diffraction of the Y nanoparticles gives lattice spacings corresponding to the cubic structure of yttrium oxide (Y2O3). The most optimal dopant content for luminescence of Y:Eu and Y:Tb nanoparticles in apoferritin cavity are about 60% and 40%, respectively.

  3. Mechanical properties of rare earth stannate pyrochlores

    NASA Astrophysics Data System (ADS)

    Feng, J.; Xiao, B.; Qu, Z. X.; Zhou, R.; Pan, W.

    2011-11-01

    The RE2Sn2O7 series compounds (RE = La, Nb, Sm, Gd, Er, Yb) with a pyrochlore structure are prepared by co-precipitation method. The bulk, shear, Young's moduli, B/G, and Poisson's ratios are calculated using density functional theory and also measured by ultrasonic resonance method. The theoretical values of lattice constants and mechanical moduli are smaller than experimental results. The electronic structures of RE2Sn2O7 are analogous to RE2Zr2O7. La2Sn2O7 exhibits stronger ionic bonds than others. The covalent interactions are slightly enhanced in the heavy rare earth stannate pyrochlores. The Vickers harnesses of RE2Sn2O7 are measured experimentally, which are smaller than theoretical predictions.

  4. Thermoelectric properties of rare earth chalcogenides

    NASA Technical Reports Server (NTRS)

    Danielson, L. R.; Raag, V.; Wood, C.

    1985-01-01

    The rare earth chalcogenides are important thermoelectric materials due to their high melting points, self-doping capabilities, and low thermal conductivities. Lanthanum sulfides and lanthanum tellurides have been synthesized in quartz ampules, hot-pressed into samples, and measured. The n-type Seebeck coefficients, electrical resistivities, and power factors generally all increased as the temperature increased from 200 to 1000 C. The figure-of-merit for nonstoichiometric lanthanum telluride was 0.001/deg C at 1000 C, considerably higher than for silicon-germanium. Thermoelectric measurements were made for LaTe(2) and YbS(1.4), and p-type behavior was observed for these compounds from 300 to 1100 C.

  5. Rare earths and other trace elements in Luna 16 soil.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Haskin, L. A.

    1972-01-01

    An analysis has been made of four small samples of material brought to earth by the Luna 16 mission, with the aim to determine rare earths and other trace elements in these samples. The analytical results are tabulated, and the rare earth abundances are compared with the average for chondrites. A comparison is also made with the results of similar analyses of Apollo samples.

  6. CADMIUM-RARE EARTH BORATE GLASS AS REACTOR CONTROL MATERIAL

    DOEpatents

    Ploetz, G.L.; Ray, W.E.

    1958-11-01

    A reactor control rod fabricated from a cadmiumrare earth-borate glass is presented. The rare earth component of this glass is selected from among those rare earths having large neutron capture cross sections, such as samarium, gadolinium or europium. Partlcles of this glass are then dispersed in a metal matrix by standard powder metallurgy techniques.

  7. Restoration of rare earth mine areas: organic amendments and phytoremediation.

    PubMed

    Zhou, Lingyan; Li, Zhaolong; Liu, Wen; Liu, Shenghong; Zhang, Limin; Zhong, Liyan; Luo, Ximei; Liang, Hong

    2015-11-01

    Overexploitation of rare earth mine has caused serious desertification and various environmental issues, and ecological restoration of a mining area is an important concern in China. In this study, experiments involving dry grass landfilling, chicken manure broadcasting, and plant cultivation were carried out to reclaim a rare earth mine area located in Heping County, Guangdong Province, China. The prime focus was to improve soil quality in terms of nutrients, microbial community, enzyme activity, and physicochemical properties so as to reclaim the land. After 2 years of restoration, an increase of organic matter (OM), available potassium (K), available phosphorus (P) levels, and acid phosphatase (ACP) activity and a reduction of the available nitrogen (N) level and urease (URE) activity in soil were achieved compared to the original mined land. The nutrients and enzyme activities in soil with 5 years of restoration were close to or surpass those in the unexploited land as control. The bulk density, total porosity, water holding capacity, pH, and electrical conductivity (EC) of soil were improved, and the number of cultivable microorganisms and the bacterial diversity in soil were greatly increased with time during ecological restoration, especially for surface soil. Furthermore, the artificial vegetation stably grew at the restored mining sites. The results indicated that organic amendments and phytoremediation could ecologically restore the rare earth mining sites and the mined land could finally be planted as farmland.

  8. Thermochemistry of Rare Earth Silicates for Environmental Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

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

  9. Synthesis, characterization, antioxidant activity and DNA-binding studies of two rare earth(III) complexes with naringenin-2-hydroxy benzoyl hydrazone ligand.

    PubMed

    Li, Tian-Rong; Yang, Zheng-Yin; Wang, Bao-Dui; Qin, Dong-Dong

    2008-08-01

    Two novel rare earth complexes, Y(III) complex (1) and Eu(III) complex (2), with naringenin-2-hydroxy benzoyl hydrazone ligand were synthesized and characterized. The interaction of the two metal complexes and the free ligand with calf thymus DNA (CT DNA) was investigated by electronic absorption spectroscopy, fluorescence spectroscopy and viscosity measurement. All the experimental evidences indicate that these three compounds can strongly bind to CT DNA via an intercalation mechanism. The intrinsic binding constants of the Y(III) complex (1), Eu(III) complex (2) and the free ligand with CT DNA were 2.1 x 10(4), 8.5 x 10(4) and 1.6 x 10(4) M(-1), respectively. Furthermore, the antioxidant activity of the metal complexes was determined by hydroxyl radical scavenging method in vitro.

  10. Rare Earth Elements in National Defense: Background, Oversight Issues, and Options for Congress

    DTIC Science & Technology

    2011-03-31

    light rare earths (lanthanum, cerium, praseodymium , neodymium, promethium, samarium) and heavy rare earths (europium, gadolinium, terbium, dysprosium...rare earth elements cerium, lanthanum, praseodymium , and neodymium. However, the Mountain Pass mine will not immediately be able to refine rare earth

  11. Enhanced pinning in mixed rare earth-123 films

    DOEpatents

    Driscoll, Judith L.; Foltyn, Stephen R.

    2009-06-16

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

  12. VUV spectroscopic properties of rare-earth (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Jun; Zhang, Shao-Lin; Zhang, Wei-Bin; Yang, Woochul

    2017-02-01

    Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE3+- activated (RE3+ = Sm3+, Eu3+, Tb3+ and Dy3+) Ba6Gd9B79O138 borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE3+-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm3+-activated BGBO, the charge transfer transition from O2- to Sm3+ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm3+f-f transitions of 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2). The O2--Eu3+ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu3+-doped BGBO. For Tb3+-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb3+, respectively. In addition, the absence of the f-d transitions of Sm3+ and Dy3+ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators.

  13. SALICYLATE PROCESS FOR THORIUM SEPARATION FROM RARE EARTHS

    DOEpatents

    Cowan, G.A.

    1959-08-25

    The separation of thorium from rare earths is accomplished by forming an aqueous solution of salts of thorium and rare earths and sufficient acetate buffer to provide a pH of between 2 and 5, adding an ammonium salicylate to the aqueous buffered solution, contacting the resultant solution with a substantially water-immiscible organic solvent mixture of an ether and an ester, and separating the solvent extract phase containing thorium salicylate from the aqueous phase containing the rare earths.

  14. China’s Rare Earth Policies: Economic Statecraft or Interdependence?

    DTIC Science & Technology

    2012-12-01

    Ministry of Land and Resources MOC Ministry of Commerce NdFeB Neodymium Iron Boron NDRC National Development and Reform...SmCo) and neodymium iron boron (NdFeB). NdFeB magnets, known to be the world’s strongest permanent magnets, monopolize rare earth magnet usage in...that there will likely be shortages of other light rare earths and many heavy rare earths (i.e., dysprosium, terbium, neodymium , europium and erbium

  15. Decomposition of Rare Earth Loaded Resin Particles

    SciTech Connect

    Voit, Stewart L; Rawn, Claudia J

    2010-09-01

    resin is made of sulfonic acid functional groups attached to a styrene divinylbenzene copolymer lattice (long chained hydrocarbon). The metal cation binds to the sulfur group, then during thermal decomposition in air the hydrocarbons will form gaseous species leaving behind a spherical metal-oxide particle. Process development for resin applications with radioactive materials is typically performed using surrogates. For americium and curium, a trivalent metal like neodymium can be used. Thermal decomposition of Nd-loaded resin in air has been studied by Hale. Process conditions were established for resin decomposition and the formation of Nd{sub 2}O{sub 3} particles. The intermediate product compounds were described using x-ray diffraction (XRD) and wet chemistry. Leskela and Niinisto studied the decomposition of rare earth (RE) elements and found results consistent with Hale. Picart et al. demonstrated the viability of using a resin loading process for the fabrication of uranium-actinide mixed oxide microspheres for transmutation of minor actinides in a fast reactor. For effective transmutation of actinides, it will be desirable to extend the in-reactor burnup and minimize the number of recycles of used actinide materials. Longer burn times increases the chance of Fuel Clad Chemical or Mechanical Interaction (FCCI, FCMI). Sulfur is suspected of contributing to Irradiation Assisted Stress Corrosion Cracking (IASCC) thus it is necessary to maximize the removal of sulfur during decomposition of the resin. The present effort extends the previous work by quantifying the removal of sulfur during the decomposition process. Neodymium was selected as a surrogate for trivalent actinide metal cations. As described above Nd was dissolved in nitric acid solution then contacted with the AG-50W resin column. After washing the column, the Nd-resin particles are removed and dried. The Nd-resin, seen in Figure 1 prior to decomposition, is ready to be converted to Nd oxide microspheres.

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

    NASA Astrophysics Data System (ADS)

    Ding, Kaihong

    2014-07-01

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

  17. Improved Rare-Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Goebel, Dan M.

    2011-01-01

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

  18. Di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands: synthesis, characterization and catalytic activity towards isoprene 1,4-cis polymerization.

    PubMed

    Zhang, Guangchao; Deng, Baojia; Wang, Shaowu; Wei, Yun; Zhou, Shuangliu; Zhu, Xiancui; Huang, Zeming; Mu, Xiaolong

    2016-10-21

    Different di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands were synthesized and their catalytic activities towards isoprene polymerization were investigated. Treatment of [RE(CH2SiMe3)3(thf)2] with 1 equiv. of 3-(CyN[double bond, length as m-dash]CH)C8H5NH in toluene or in THF afforded dinuclear rare-earth metal alkyl complexes having indolyl ligands in different hapticities with central metals {[η(2):η(1)-μ-η(1)-3-(CyNCH(CH2SiMe3))Ind]RE-(thf)(CH2SiMe3)}2 (Cy = cyclohexyl, Ind = Indolyl, RE = Yb (1), Er (2), Y (3)) or {[η(1)-μ-η(1)-3-(CyNCH(CH2SiMe3))Ind]RE-(thf)2(CH2SiMe3)}2 (RE = Yb (4), Er (5), Y (6), Gd (7)), respectively. These two series of dinuclear complexes could be transferred to each other easily by only changing the solvents in the process. Reaction of [Er(CH2SiMe3)3(thf)2] with 1 equiv. of 3-t-butylaminomethylindole 3-((t)BuNHCH2)C8H5NH in THF afforded the unexpected trinuclear erbium alkyl complex [η(2):η(1)-μ-η(1)-3-((t)BuNCH2)Ind]4Er3(thf)5(CH2SiMe3) (8), which can also be prepared by reaction of 3 equiv. of [Er(CH2SiMe3)3(thf)2] with 4 equiv. of 3-((t)BuNHCH2)C8H5NH in THF. Accordingly, complexes [η(2):η(1)-μ-η(1)-3-((t)BuNCH2)Ind]4RE3(thf)5(CH2SiMe3) (RE = Y (9), Dy (10)) were prepared by reactions of 3 equiv. of [RE(CH2SiMe3)3(thf)2] with 4 equiv. of 3-((t)BuNHCH2)C8H5NH in THF. Reactions of [RE(CH2SiMe3)3(thf)2] with 1 equiv. of 3-t-butylaminomethylindole 3-((t)BuNHCH2)C8H5NH in THF, followed by treatment with 1 equiv. of [(2,6-(i)Pr2C6H3)N[double bond, length as m-dash]CHNH(C6H3(i)Pr2-2,6)] afforded, after workup, the dinuclear rare-earth metal complexes [η(1)-μ-η(1):η(1)-3-((t)BuNCH2)Ind][η(1)-μ-η(1):η(3)-3-((t)BuNCH2)Ind]RE2(thf)[(η(3)-2,6-(i)Pr2C6H3)NCHN(C6H3(i)Pr2-2,6)]2(RE = Er (11), Y (12)) having the indolyl ligands bonded with the rare-earth metal in different ligations. All new complexes 1-12 were fully characterized by spectroscopic methods and elemental analyses, and

  19. Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

    PubMed

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

    2009-01-01

    Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

  20. Analysis of Indian blue ballpoint pen inks tagged with rare-earth thenoyltrifluoroacetonates by inductively coupled plasma-mass spectrometry and instrumental neutron activation analysis.

    PubMed

    Maind, S D; Kumar, S A; Chattopadhyay, N; Gandhi, Ch; Sudersanan, M

    2006-05-25

    Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.

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

    PubMed

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

    2012-03-01

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

  2. APPLICATION OF MECHANICAL ACTIVATION TO PRODUCTION OF PYROCHLORE CERAMIC CONTAINING SIMULATED RARE-EARTH ACTINIDE FRACTION OF HLW

    SciTech Connect

    Stefanovsky, S.V.; Kirjanova, O.I.; Chizhevskaya, S.V.; Yudintsev, S.V.; Nikonov, B.S.

    2003-02-27

    Samples of zirconate pyrochlore ceramic (REE)2(Zr,U)2O7 (REE = La-Gd) containing simulated REE-An fraction of HLW were synthesized by two routes: (1) conventional cold compaction of oxide mixtures in pellets under pressure of 200 MPa and sintering of the pellets at 1550 C for 24 hours; and (2) using preliminary mechanical activation of oxide powders in a linear inductive rotator (LIV-0.5E) and a planetary mill - activator with hydrostatic yokes (AGO-2U) for 5 or 10 min. All the samples sintered at 1550 C were monolithic and dense with high mechanical integrity. As follows from X-ray diffraction (XRD) data, the ceramic sample produced without mechanical activation is composed of pyrochlore as major phase but contains also minor unreacted oxides. The samples prepared from pre-activated mixtures are composed of the pyrochlore structure phase only. Scanning electron microscopy (SEM) data also show higher structural and compositional homogeneity of the samples prepared from mechanically activated batches. The samples produced from oxide mixtures mechanically activated in the LIV for 10 min were slightly contaminated with iron resulting in formation of minor perovskite structure phase not detected by XRD but seen on SEM-images of the samples. Comparison of the samples prepared from non-activated and activated batches showed higher density, lower open porosity, water uptake, and elemental leaching for the samples fabricated from mechanically activated oxide mixtures.

  3. Rare earth element diffusion in natural enstatite

    NASA Astrophysics Data System (ADS)

    Cherniak, Daniele J.; Liang, Yan

    2007-03-01

    Chemical diffusion coefficients of La, Nd, Eu, Gd, and Yb in natural enstatite have been measured at 850-1250 °C and 1 atm. Anhydrous diffusion experiments were run in Pt capsules in air, or in sealed silica glass capsules under an iron-wüstite (IW) solid buffer. The sources of diffusant were pre-reacted mixtures of synthetic enstatite powder and microcrystalline rare-earth aluminate garnet. Rutherford Backscattering Spectrometry (RBS) was used to measure diffusion profiles. For Gd diffusion in air over the temperature range 1000-1250 °C, the following Arrhenius relation is found for diffusion normal to (210): D=2.55×10-9exp(321±85mol /RT)ms-1. There is no significant difference between Gd diffusion in air and under IW-buffered conditions. Behavior similar to Gd is also noted for Nd. The Arrhenius relationship for Eu diffusion in enstatite, normal to (210) and at 850-1150 °C and IW-buffered conditions, is D=6.93×10-6exp(-384±29mol /RT)ms-1. For Eu diffusion in air over the temperature range 1000-1200 °C for the same orientation, the following Arrhenius relation is found: D=1.70×10-8exp(-350±42mol /RT)ms-1. For Eu diffusion under IW-buffered conditions and for experiments run in air, diffusivities normal to (001) are similar to those for diffusion normal to (210). Eu diffusion under IW-buffered conditions is more than an order of magnitude faster than Eu diffusion in air. It is likely that majority of Eu is in the divalent state for diffusion under IW-buffered conditions, but Eu is in the trivalent state for diffusion in air. In the case of Nd and Gd, where valence state does not change under the investigated fO 2 conditions, diffusivities measured for experiments run both in air and under IW-buffered conditions are comparable to those obtained for trivalent Eu. Further, measurements of La, Nd, Eu +3, Gd, and Yb diffusion suggest that diffusion of trivalent REE in enstatite is not sensitive to ionic size, in contrast to that observed for REE diffusion in

  4. Occupational radiation exposure due to norm in a rare-earth compounds production facility.

    PubMed

    Haridasan, P P; Pillai, P M B; Tripathi, R M; Puranik, V D

    2008-01-01

    In India, rare-earth compounds are produced from the beach sand mineral monazite. Caustic digestion of the mineral followed by selective acid extraction is the method used to separate composite rare-earth fraction. The composite rare-earth chloride contains low levels of natural radionuclides and is the starting material for individual rare-earth compounds which have wide applications. Activity concentrations in composite rare-earth compounds such as chlorides, fluorides, carbonates and oxides of Ce, Nd, Pr, Sm, Gd, etc. are presented in this paper. The external gamma exposure rates and airborne activity due to thorium and thoron progeny in the occupational environment are studied. The activity levels in liquid effluent are presented. The potential individual occupational dose is estimated to be 1.9 mSv per annum.

  5. Google Earth locations of USA and seafloor hydrothermal vents with associated rare earth element data

    SciTech Connect

    Andrew Fowler

    2016-02-10

    Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal vents that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal Vents" and "Rare earth element content of thermal fluids from Surprise Valley, California"

  6. Rare earth element enrichment using membrane based solvent extraction

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  7. Optical Properties of Nd Doped Rare Earth Vanadates (Preprint)

    DTIC Science & Technology

    2010-07-01

    common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and gadolinium vanadate are being used for their...state laser hosts such as YAG. While the most common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and

  8. How PNNL Extracts Rare Earth Elements from Geothermal Brine

    SciTech Connect

    2016-07-12

    By looking at a problem at a nanoscale level, PNNL researchers are developing an economic way to extract valuable rare earth elements from geothermal fluids. This novel approach may help meet the high demand for rare earth elements that are used in many clean energy technologies.

  9. [Rare-earth metals as a factor in mutagenicity].

    PubMed

    Solovykh, G N; Golinskaia, L V; Kanunikova, E A

    2012-01-01

    Both the regions of the Orenburg Region area and individual examined streams and reservoirs were shown to be characterized by a varying load index for rare earth elements. The total level of rare earth elements was directly correlated with different types of mutations.

  10. Tunable, rare earth-doped solid state lasers

    DOEpatents

    Emmett, John L.; Jacobs, Ralph R.; Krupke, William F.; Weber, Marvin J.

    1980-01-01

    Laser apparatus comprising combinations of an excimer pump laser and a rare earth-doped solid matrix, utilizing the 5d-4f radiative transition in a rare earth ion to produce visible and ultra-violet laser radiation with high overall efficiency in selected cases and relatively long radiative lifetimes.

  11. Rare-earth occurrences in the Pea Ridge tailings

    SciTech Connect

    Vierrether, C.W.; Cornell, W.I.

    1993-01-01

    Tailings from the Pea Ridge iron mine contain significant amounts of apatite, which has rare-earth element values associated with it. In association with the recovery of rare-earth minerals as a secondary resource, the US Bureau of Mines conducted an investigation on the recoverability of the rare-earth minerals from the tailings. The mill tailings were subjected to a phosphate flotation to separate the apatite from other constituents. More than 70-pct recovery of the rare-earth values was achieved. Based on mineralogical characterization and prior analysis of rare-earth-bearing breccia pipe material at Pea Ridge, it is proposed that processing this phosphate concentrate on a vanner table would yield up to a 95-pct recovery of the rare earths in the concentrate, with the apatite reporting to the tailings. Intensive ore microscopy studies of the original tailings to the flotation products led to the identification of monazite, xenotime, and rare-earth-enriched apatite as the major rare-earth-bearing minerals in the tailings.

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

    DOEpatents

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

    1963-02-26

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

  13. Microemulsion synthesis of nanosized TiO(2) particles doping with rare-earth and their photocatalytic activity.

    PubMed

    Jian, Zicong; Pu, Yuying; Fang, Jianzhang; Ye, Zhiping

    2010-01-01

    Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO(2) and Ce-TiO(2) particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO(2) with doping TiO(2) , the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.

  14. Antihuman Immunodeficiency Virus Type 1 (HIV-1) Activity of Rare Earth Metal Complexes of 4-Hydroxycoumarins in Cell Culture

    PubMed Central

    Manolov, Ilia; Raleva, Sevda; Genova, Petya; Savov, Alexey; Froloshka, Liliana; Dundarova, Daniela; Argirova, Radka

    2006-01-01

    The cerium Ce(III), lanthanum La(III), and neodymium Nd(III) complexes with 4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one (warfarin) (W) and 3,3′-benzylidenebis[4-hydroxycoumarin] (1) were synthesized and studied for the first time for cytotoxicity (on MT-2 cells) and as anti-HIV agents under acute and chronic infection. The complexes were characterized by different physicochemical methods: mass spectrometry, 1H NMR, 13C NMR, and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligands. Anti-HIV effect of the complexes/ligands was measured in MT-2 cells by microtiter infection assay. Detection of endogenous reverse transcriptase (RT) activity and RT processivity by PCR indicative for proviral DNA synthesis demonstrated that anti-HIV activity has not been linked to early stages of viral replication. No effect on late steps of viral replication has been found using cells chronically producing HIV-1LAI virus. La(W) demonstrated anti-HIV activity (IC50=21.4 μM) close to maximal nontoxic concentration. Nd(W), Ce(1), and Nd(1) demonstrated limited anti-HIV potency, so none of the complexes seems appropriate to be used in clinic. Further targeting of HIV-1 inhibition by La(W) is under progress. PMID:17497016

  15. Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

    PubMed

    Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

    2014-02-28

    Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (λ>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst.

  16. Rare earth elements in Hamersley BIF minerals

    NASA Astrophysics Data System (ADS)

    Alibert, Chantal

    2016-07-01

    Minerals from the Hamersley banded iron formation, Western Australia, were analyzed for Y and rare earth elements (YREEs) by laser ablation ICP-MS to investigate diagenetic pathways, from precursor phases to BIF minerals. One group of apatites carries the seawater REE signature, giving evidence that P and REEs, thoroughly scavenged from the water column by Si-ferrihydrite particles, were released upon microbial Fe3+ reductive dissolution of Si-ferrihydrite in pore-water and finally sequestered mainly in authigenic apatite. The absence of fractionation between apatite and seawater suggests that REE were first incorporated into an amorphous calcium phosphate as fully hydrated cations, i.e. as outer-sphere complexes. The iron oxides and carbonates carry only a small fraction of the whole-rock REE budget. Their REE patterns are distinctly enriched in Yb and show some M-type tetrad effect consistent with experimental Kd(REE) between solid and saline solution with low carbonate ion concentrations. It is deduced that hematite formed at an incipient stage of Fe2+-catalyzed dissolution of Si-ferrihydrite, via a dissolution-reprecipitation pathway. The REE pattern of greenalite, found as sub-micron particles in quartz in a chert-siderite sample, is consistent with its authigenic origin by precipitation in pore-water after dissolution of a small amount of Si-ferrihydrite. Magnetite carries very low YREEs (ppb-level), has an homogeneous pattern distinctly enriched in the mid-REEs compared to hematite, and includes a late population depleted in light-REEs, Ba and As. Magnetite forming aggregates and massive laminae is tentatively interpreted as reflecting some fluid-aided hematite-magnetite re-equilibration or transformation at low-grade metamorphic temperatures.

  17. METHOD OF MAKING ALLOYS OF SECOND RARE EARTH SERIES METALS

    DOEpatents

    Baker, R.D.; Hayward, B.R.

    1963-01-01

    >This invention relates to a process for alloying the second rare earth series metals with Mo, Nb, or Zr. A halide of the rare earth metal is mixed with about 1 to 20 at.% of an oxide of Mo, Nb, or Zr. Iodine and an alkali or alkaline earth metal are added, and the resulting mixture is heated in an inert atmosphere to 350 deg C. (AEC)

  18. Annual budget of Gd and related Rare Earth Elements in a river basin heavily disturbed by anthropogenic activities.

    NASA Astrophysics Data System (ADS)

    Hissler, Christophe; Stille, Peter; Guignard, Cédric; François Iffly, Jean; Pfister, Laurent

    2014-05-01

    The real environmental impact of micropollutants in river systems can be difficult to assess, essentially due to uncertainties in the estimation of the relative significance of both anthropogenic and natural sources. The natural geochemical background is characterized by important variations at global, regional or local scales. Moreover, elements currently considered to be undisturbed by human activities and used as tracers of continental crust derived material have become more and more involved in industrial or agricultural processes. The global production of lanthanides (REE), used in industry, medicine and agriculture, for instance, has increased exponentially from a few tons in 1950 to projected 185 kt in 2015. Consequently, these new anthropogenic contributions impact the natural cycle of the REE. Gd and related REE are now worldwide recognized as emergent micropollutants in river systems. Nevertheless, there is still a gap concerning their temporal dynamics in rivers and especially the quantification of both the anthropogenic and natural contributions in surface water. The acquisition of such quantitative information is of primordial interest because elements from both origins may present different bioavailability and toxicity levels. Working at the river basin scale allows for quantifying micropollutant fluxes. For this reason, we monitored water quality and discharge of the Alzette River (Luxembourg, Europe) over two complete hydrological cycles (2010-2013). The substantial contamination, is principally due to the steel industry in the basin, which has been active from 1875 until now, and to the related increase of urban areas. The particulate and dissolved fractions of river water were monitored using a multitracer approach (standard parameters for water quality including REE concentrations, Pb, Sr, Nd radiogenic isotopes) with two sampling setups (bi-weekly and flood event based sampling). This extensive sampling design allowed quantifying the annual

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

    PubMed

    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.

  20. Effects of spraying rare earths on contents of rare Earth elements and effective components in tea.

    PubMed

    Wang, Dongfeng; Wang, Changhong; Ye, Sheng; Qi, Hongtao; Zhao, Guiwen

    2003-11-05

    Rare earth (RE) fertilizer is widely applied in China to increase the yield and the quality of crops including tea. However, the effects of spraying RE fertilizer on the contents of rare earth elements (REE) and effective components in tea are unknown. The results from basin and field experiments show that the values of the REE concentrations in new shoots of tea plants and the concentration of REE in the soil (REE/REEs) either from control basins or from treatment basins were smaller than those in other parts of tea plant and similar between control and treatment. The longer the interval between spraying RE fertilizer and picking the shoots of tea plants, the less the effects from spraying. About 80% summation operator REE (the sum of the concentrations of 15 REE) in tea, whether it came from spraying or not, was insoluble in the infusion. About 10% the soluble REE of summation operator REE in tea infusion was bound to polysaccharide, and the amount of REE bound polysaccharide decreased over time. At least a 25 day safety interval is needed between spraying and picking if the microelement fertilizer is used, in order to enhance tea output and to ensure tea safety.

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

    PubMed

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

    2009-06-01

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

  2. Bioleaching of rare earth elements from monazite sand.

    PubMed

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

    2016-02-01

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

  3. Investigations into Rare Earth Oxide Use and Behaviour

    NASA Astrophysics Data System (ADS)

    Pryce, Owen

    2010-05-01

    Quinton, 2008), and alternative REO extraction methods was compared using tagged and untagged soils. Extractions were also performed upon REO powders and a certified reference soil to identify which of the commonly used REOs are unsuitable for tracing studies. This paper will also report on investigations into the transport behaviour of REO tracers at different slope gradients, including comparisons between the transport of sediment bound phosphorus and REOs. References: Kimoto, A., Nearing, M., Shipitalo, M., Polyakov, V., 2006. Multi-year tracking of sediment sources in a small agricultural watershed using rare earth elements. Earth Surface Processes and Landforms, 31, pp.1763-1774. Li, M., Li, Z., Ding, W., Liu, P., Yao, W., 2006. Using rare earth element tracers and neutron activation analysis to study rill erosion processes. Applied Radiation and Isotopes, 64, pp.402-408. Polyakov, V., Nearing, M., Shipitalo, M., 2004. Tracking sediment redistribution in a small watershed: Implications for agro-landscape evolution. Earth Surface Processes and Landforms, 29, pp.1275-1291. Stevens, C., Quinton, J., 2008. Investigating source areas of eroded sediments transported in concentrated overland flow using rare earth element tracers. Catena, 74, pp.31-36. Zhang, X., Friedrich, J., Nearing, M., Norton, L., 2001. Potential use of Rare Earth Oxides as Tracers for Soil Erosion and Aggregation Studies. Soil Science Society of America Journal, 65, pp.1508-1515. Zhang, X., Nearing, M., Polyakov, V., Friedrich, J., 2003. Using Rare-Earth Oxide Tracers for Studying Soil Erosion Dynaimcs. Soil Science Society of America Journal, 67, pp.279-288.

  4. Structure and Properties of Rare Earth Aluminosilicate Glasses.

    NASA Astrophysics Data System (ADS)

    Kohli, Jeffrey Todd

    1991-02-01

    Rare earth aluminosilicate (REAS) glasses have been formed using conventional melting techniques. The glass-forming regions of six different ternary systems have been defined with praseodymium, neodymium, samarium, terbium, erbium, or ytterbium oxides, with alumina and silica. The glass-forming regions systematically decreased in size as the atomic number of the particular rare earth in the ternary systems increased. Glasses, of the molar composition 2R_2O_3 -2Al_2O_3 -6SiO_2, were formed with twelve of the fourteen true rare earth oxides in order to investigate further effects related to the identity of the rare earth ion in the glasses. Several properties of the rare earth aluminosilicate glasses were measured. These properties include: thermal expansion, glass transformation temperature, dilatometric softening point, density, molar volume, index of refraction, Vicker's hardness, magnetic susceptibility and the Faraday rotatory response. The structures of rare earth aluminosilicate glasses were investigated using infrared and Raman spectroscopies as well as magic angle spinning nuclear magnetic resonance (MAS-NMR). MAS-NMR provided information regarding the local environments of silicon and aluminum ions in yttrium aluminosilicate (YAS) glasses. Since the size and valence of the yttrium ion are similar to the true rare earth ions, and the properties of the REAS and YAS glasses are similar, it is believed that the structures of yttrium aluminosilicate glasses are similar to those of the true rare earth aluminosilicate glasses. Several rare earth aluminogermanate glasses, having the molar formula 2R_2O _3-2Al_2O _3-6GeO_2, were also formed using conventional melting techniques. The properties of these glasses were compared and contrasted with those of the REAS glasses. Finally, a chapter on the study of magnetic susceptibility in common insulator glasses was added to the thesis. Several techniques used to measure magnetic susceptibility are reviewed in this chapter

  5. The Effect of Fulvic Acid on the Leaching of a Weathered Rare-Earth Ore

    NASA Astrophysics Data System (ADS)

    Luo, Xian-ping; Feng, Bo; Wang, Peng-cheng; Zhou, He-peng; Chen, Xiao-ming

    2015-12-01

    The effect of fulvic acid on the leaching of a weathered crust elution-deposited rare-earth ore, using ammonium sulfate as lixiviant, has been investigated. The results show that fulvic acid can enhance the leaching process effectively. With the addition of fulvic acid to the lixiviant at a concentration of 0.1 wt pct, the leaching extraction of rare-earth elements increased by 8.38 pct and the ammonium sulfate concentration decreased by 25 wt pct. Fulvic acid promotes the leaching process. It also reacts with rare-earth ions, forms soluble complexes, reduces the activity of the leached rare-earth ions, and increases the concentration difference of ion diffusion. These results highlight a new approach for making the leaching process of low-grade weathered crust elution-deposited rare-earth ore more efficient and also for lowering the lixiviant consumption.

  6. Minerals yearbook, 1988. Rare-earth minerals and metals

    SciTech Connect

    Hedrick, J.B.; Templeton, D.A.

    1988-01-01

    Domestic production of rare-earth concentrates decreased in 1988. Foreign sources of processed rare earths obtained a slightly larger share of the U.S. market, while domestic exports saw a marked increase compared to 1987 levels. Rare earths were used in high-technology applications such as laser crystals, high-strength permanent magnets, optical fibers, magnetic resonance imaging (MRI) scanners, and high-temperature superconductors. Topics discussed in the report include domestic data coverage, legislation and government programs, environmental issues, domestic production, consumption and uses, stocks, prices, foreign trade, world capacity, world review--Australia, Brazil, Canada, China, Egypt, Greenland, Japan, Madagascar, Malaysia, Mozambique, Sri Lanka, Thailand--and technology.

  7. Rare-earth-metal alkylaluminates supported by N-donor-functionalized cyclopentadienyl ligands: C-H bond activation and performance in isoprene polymerization.

    PubMed

    Jende, Lars N; Maichle-Mössmer, Cäcilia; Anwander, Reiner

    2013-11-25

    Homoleptic tetramethylaluminate complexes [Ln(AlMe4)3] (Ln=La, Nd, Y) reacted with HCp(NMe2) (Cp(NMe2) =1-[2-(N,N-dimethylamino)-ethyl]-2,3,4,5-tetramethyl-cyclopentadienyl) in pentane at -35 °C to yield half-sandwich rare-earth-metal complexes, [{C5 Me4CH2CH2NMe2 (AlMe3)}Ln(AlMe4)2]. Removal of the N-donor-coordinated trimethylaluminum group through donor displacement by using an equimolar amount of Et2O at ambient temperature only generated the methylene-bridged complexes [{C5Me4CH2CH2NMe(μ-CH2)AlMe3}Ln(AlMe4)] with the larger rare-earth-metal ions lanthanum and neodymium. X-ray diffraction analysis revealed the formation of isostructural complexes and the C-H bond activation of one aminomethyl group. The formation of Ln(μ-CH2)Al moieties was further corroborated by (13)C and (1)H-(13)C HSQC NMR spectroscopy. In the case of the largest metal center, lanthanum, this C-H bond activation could be suppressed at -35 °C, thereby leading to the isolation of [(Cp(NMe2))La(AlMe4)2], which contains an intramolecularly coordinated amino group. The protonolysis reaction of [Ln(AlMe4)3] (Ln=La, Nd) with the anilinyl-substituted cyclopentadiene HCp(AMe2) (Cp(AMe2) =1-[1-(N,N-dimethylanilinyl)]-2,3,4,5-tetramethylcyclopentadienyl) at -35 °C generated the half-sandwich complexes [(Cp(AMe2))Ln(AlMe4)2]. Heating these complexes at 75 °C resulted in the C-H bond activation of one of the anilinium methyl groups and the formation of [{C5Me4C6H4NMe(μ-CH2)AlMe3}Ln(AlMe4)] through the elimination of methane. In contrast, the smaller yttrium metal center already gave the aminomethyl-activated complex at -35 °C, which is isostructural to those of lanthanum and neodymium. The performance of complexes [{C5Me4CH2CH2NMe(μ-CH2 )AlMe3}-Ln(AlMe4)], [(Cp(AMe2))Ln(AlMe4)2], and [{C5Me4C6H4NMe(μ-CH2)AlMe3}Ln(AlMe4)] in the polymerization of isoprene was investigated upon activation with [Ph3C][B(C6F5)4], [PhNMe2 H][B(C6F5)4], and B(C6F5)3. The highest stereoselectivities were observed

  8. Pb and rare earth element diffusion in xenotime

    NASA Astrophysics Data System (ADS)

    Cherniak, D. J.

    2006-05-01

    Diffusion of Pb and the rare earth elements Sm, Dy and Yb have been characterized in synthetic xenotime under dry conditions. The synthetic xenotime was grown via a Na 2CO 3-MoO 3 flux method. The sources of diffusant for the rare earth diffusion experiments were REE phosphate powders, with experiments run using sources containing a single REE. For Pb, the source consisted a mixture of YPO 4 and PbTiO 3. Experiments were performed by placing source and xenotime in Pt capsules, and annealing capsules in 1 atm furnaces for times ranging from 30 min to several weeks, at temperatures from 1000 to 1500 °C. The REE and Pb distributions in the xenotime were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relations are obtained for diffusion in xenotime, normal to (101): D=1.5×10exp⁡(-441±12 kJmol/R⁢T)ms.D=9.0×10exp⁡(-349±16 kJmol/R⁢T)ms.D=3.9×10exp⁡(-362±13 kJmol/R⁢T)ms. Diffusivities among the REE do not differ greatly in xenotime over the investigated temperature range, in contrast to findings for the REE in zircon [Cherniak, D.J., Hanchar, J.M., Watson, E.B., 1997. Rare earth diffusion in zircon. Chem. Geol. 134, 289-301.], where the LREE diffuse more slowly, and with higher activation energies for diffusion, than the heavier rare earths. In zircon, these differences among diffusion of the rare earths are attributed to the relatively large size of the REE with respect to Zr, for which they likely substitute in the zircon lattice. With the systematic increase in ionic radius from the heavy to lighter REE, this size mismatch becomes more pronounced and diffusivities of the LREE are as consequence slower. Although xenotime is isostructural with zircon, the REE are more closely matched in size to Y, so in xenotime this effect appears much smaller and the REE diffuse at similar rates. In addition, the process of diffusion in xenotime likely involves simple REE + 3 → Y + 3 exchange, without charge compensation as needed

  9. Compact Rare Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

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

  10. Magneto-Optical Experiments on Rare Earth Garnet Films.

    ERIC Educational Resources Information Center

    Tanner, B. K.

    1980-01-01

    Describes experiments in which inexpensive or standard laboratory equipment is used to measure several macroscopic magnetic properties of thin rare earth garnet films used in the manufacture of magnetic bubble devices. (Author/CS)

  11. Growth of rare-earth monolayers on synthetic fluorine mica

    NASA Astrophysics Data System (ADS)

    Tsui, F.; Han, P. D.; Flynn, C. P.

    1993-05-01

    We have grown single-crystal rare-earth films on cleaved faces of synthetic fluorine mica fluorophlogopite by molecular-beam-epitaxy techniques. This has made it possible to measure material properties such as magnetism in monolayer structures.

  12. Magnetoelastic contribution to thermal expansion of rare-earth zircons

    NASA Astrophysics Data System (ADS)

    Kazei, Z. A.; Kolmakova, N. P.; Shishkina, O. A.

    1998-02-01

    Comparative analysis is performed for the magnetoelastic contributions to thermal expansion of two groups of rare-earth zircons: phosphates RPO 4 (R=Y,Tb-Yb) and vanadates RVO 4 (R=Pr, Nd, Gd-Yb). Significant magnetoelastic anomalies of thermal expansion are observed and magnetoelastic contributions are found in regard to the corrections for the changes of the phonon contributions throughout the series of RPO 4 and RVO 4. Magnetoelastic contributions to thermal expansion are demonstrated to be well accounted for by the temperature dependences of the quadrupole moments of rare-earth ions both in phosphates and vanadates. The fully symmetric magnetoelastic coefficients are determined for all the rare-earth compounds under investigation; they are of the same sign and comparable magnitude in vanadates and phosphates, whereas the magnetoelastic contributions are opposite in sign for two isomorphous groups of rare-earth zircons.

  13. METHOD OF SEPARATING RARE EARTHS BY ION EXCHANGE

    DOEpatents

    Spedding, F.H.; Powell, J.E.

    1960-10-18

    A process is given for separating yttrium and rare earth values having atomic numbers of from 57 through 60 and 68 through 71 from an aqueous solution whose pH value can range from 1 to 9. All rare earths and yttrium are first adsorbed on a cation exchange resin, and they are then eluted with a solution of N-hydroxyethylethylenediaminetriacetic acid (HEDTA) in the order of decreasing atomic number, yttrium behaving like element 61; the effluents are collected in fractions. The HEDTA is recovered by elution with ammonia solution and the resin is regenerated with sulfuric acid. Rare earths are precipitated from the various effluents with oxalic acid, and each supernatant is passed over cation exchange resin for adsorption of HEDTA and nonprecipitated rare earths: the oxalic acid is not retained by the resin.

  14. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  16. Rare earths: An industry review and market outlook

    SciTech Connect

    Major-Sosias, M.A.

    1997-03-01

    A review of the global rare earths industry from production and trade, to the established and new applications that drive this unique market. The industry has been spurred by increased demand during the 1990`s, which is expected to continue into the twenty-first century. The forecast indicates additional growth, as well as the potential for the rare earths market to evolve slowly into one with a more fundamental structure.

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

    DTIC Science & Technology

    2011-03-15

    Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302. Respondents should be aware that...2010). 3 Marc Humphries , ―Rare Earth Elements: The Global Supply Chain,‖ Congressional Research Service Report for Congress R41347 (September 30...101026_Verrastro_Geopolitics_web.pdf (accessed October 14, 2010). 10 Humphries , ―Rare Earth Elements: The Global Supply Chain,‖ (September 30, 2010): 4

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  19. An Overview of Rare Earth Science and Technology

    NASA Astrophysics Data System (ADS)

    Gschneidner, Karl, Jr.

    2012-02-01

    Currently rare earth science and technology is robust: this includes all the major branches of science -- biochemistry, chemistry, materials and physics. There are, however, currently some anomalies and distortions especially in the technology and applications sector of the rare earth field, which is caused by the dominance of China on the sales of rare earths and rare earth containing products. For the past 5 to 10 years ˜95% of rare earths utilized in commerce came from China. Although Chinese actions have lead to sudden and large price spikes and export embargoes, the rare earths are still available but at a higher cost. The start up of production in 2011 at mines in the USA and Australia will alleviate this situation in about two years. Basic and applied research on the condensed matter physics/materials science has hardly been impacted by these events, but new research opportunities are opening up especially with regard to the USA's military and energy security. Magnets seems to be the hottest topic, but research on battery materials, phosphors and catalysts are also (or should be) strongly considered.

  20. Current Status on Resource and Recycling Technology for Rare Earths

    NASA Astrophysics Data System (ADS)

    Takeda, Osamu; Okabe, Toru H.

    2014-06-01

    The development of recycling technologies for rare earths is essential for resource security and supply stability because high-quality rare earth mines are concentrated in China and the demand for rare earth metals such as neodymium and dysprosium, used as raw materials in permanent magnets (neodymium magnet), is expected to increase rapidly in the near future. It is also important to establish a recycling-based society from the perspective of the conservation of finite and valuable mineral resources and the reduction of the environmental load associated with mining and smelting. In this article, the current status of rare earth resource as well as that of recycling technology for the magnets is reviewed. The importance of establishing an efficient recycling process for rare earths is discussed from the characteristics of supply chain of rare earths, and the technological bases of the recycling processes for the magnet are introduced. Further, some fundamental researches on the development of new recycling processes based on pyrometallurgical process are introduced, and the features of the recycling processes are evaluated.

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

    PubMed

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

    2016-11-16

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

  2. Interannual variation of rare earth element abundances in corals from northern coast of the South China Sea and its relation with sea-level change and human activities

    USGS Publications Warehouse

    Liu, Yajing; Peng, Z.; Wei, G.; Chen, T.; Sun, W.; He, J.; Liu, Gaisheng; Chou, C.-L.; Shen, C.-C.

    2011-01-01

    Here we present interannual rare earth element (REE) records spanning the last two decades of the 20th century in two living Porites corals, collected from Longwan Bay, close to the estuarine zones off Wanquan River of Hainan Island and Hong Kong off the Pearl River Delta of Guangdong Province in the northern South China Sea. The results show that both coral REE contents (0.5-40 ng g-1 in Longwan Bay and 2-250 ng g-1 in Hong Kong for La-Lu) are characterized with a declining trend, which are significantly negative correlated with regional sea-level rise (9.4 mm a-1 from 1981 to 1996 in Longwan Bay, 13.7 mm a-1 from 1991 to 2001 in Hong Kong). The REE features are proposed to be resulted from seawater intrusion into the estuaries in response to contemporary sea-level rise. However, the tendency for the coral Er/Nd time series at Hong Kong site is absent and there is no significant relation between Er/Nd and total REEs as found for the coral at Longwan Bay site. The observations are likely attributed to changes of the water discharge and sediment load of Pearl River, which have been significantly affected by intense human activities, such as the construction of dams/reservoirs and riverbed sediment mining, in past decades. The riverine sediment load/discharge ratio of the Pearl River decreased sharply with a rate of 0.02 kg m-3 a-1, which could make significant contribution to the declining trend of coral REE. We propose that coastal corals in Longwan Bay and similar unexplored sites with little influences of river discharge and anthropogenic disruption are ideal candidates to investigate the influence of sea-level change on seawater/coral REE. ?? 2010 Elsevier Ltd.

  3. Interannual variation of rare earth element abundances in corals from northern coast of the South China Sea and its relation with sea-level change and human activities.

    PubMed

    Liu, Yi; Peng, Zicheng; Wei, Gangjian; Chen, Tegu; Sun, Weidong; He, Jianfeng; Liu, Guijian; Chou, Chen-Lin; Shen, Chuan-Chou

    2011-02-01

    Here we present interannual rare earth element (REE) records spanning the last two decades of the 20th century in two living Porites corals, collected from Longwan Bay, close to the estuarine zones off Wanquan River of Hainan Island and Hong Kong off the Pearl River Delta of Guangdong Province in the northern South China Sea. The results show that both coral REE contents (0.5-40 ng g⁻¹ in Longwan Bay and 2-250 ng g⁻¹ in Hong Kong for La-Lu) are characterized with a declining trend, which are significantly negative correlated with regional sea-level rise (9.4 mm a⁻¹) from 1981 to 1996 in Longwan Bay, 13.7 mm a⁻¹ from 1991 to 2001 in Hong Kong). The REE features are proposed to be resulted from seawater intrusion into the estuaries in response to contemporary sea-level rise. However, the tendency for the coral Er/Nd time series at Hong Kong site is absent and there is no significant relation between Er/Nd and total REEs as found for the coral at Longwan Bay site. The observations are likely attributed to changes of the water discharge and sediment load of Pearl River, which have been significantly affected by intense human activities, such as the construction of dams/reservoirs and riverbed sediment mining, in past decades. The riverine sediment load/discharge ratio of the Pearl River decreased sharply with a rate of 0.02 kg m⁻³ a⁻¹, which could make significant contribution to the declining trend of coral REE. We propose that coastal corals in Longwan Bay and similar unexplored sites with little influences of river discharge and anthropogenic disruption are ideal candidates to investigate the influence of sea-level change on seawater/coral REE.

  4. Real World of Industrial Chemistry: Technology of the Rare Earths.

    ERIC Educational Resources Information Center

    Kremers, Howard E.

    1985-01-01

    The 17 rare earth elements account for one-fifth of the 83 naturally occurring elements and collectively rank as the 22nd most abundant "element." Properties of these elements (including their chemical similarity), their extraction from the earth, and their uses are discussed. (JN)

  5. Protecting the environment and public health from rare earth mining

    NASA Astrophysics Data System (ADS)

    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.

  6. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary rare earth metals subcategory. 421.270 Section 421.270 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Rare Earth Metals Subcategory § 421.270 Applicability: Description of the primary rare... production of rare earth metals and mischmetal by primary rare earth metals facilities......

  7. Physical and electrochemical properties of alkaline earth doped, rare earth vanadates

    NASA Astrophysics Data System (ADS)

    Adijanto, Lawrence; Balaji Padmanabhan, Venu; Holmes, Kevin J.; Gorte, Raymond J.; Vohs, John M.

    2012-06-01

    The effect of partial substitution of alkaline earth (AE) ions, Sr2+ and Ca2+, for the rare earth (RE) ions, La3+, Ce3+, Pr3+, and Sm3+, on the physical properties of REVO4 compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO4-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H2 fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode.

  8. Experimental Parameters Affecting Stripping of Rare Earth Elements from Loaded Sorptive Media in Simulated Geothermal Brines

    SciTech Connect

    Dean Stull

    2016-05-24

    Experimental results from several studies exploring the impact of pH and acid volume on the stripping of rare earth elements (REEs) loaded onto ligand-based media via an active column. The REEs in this experiment were loaded onto the media through exposure to a simulated geothermal brine with known mineral concentrations. The data include the experiment results, rare earth element concentrations, and the experimental parameters varied.

  9. Rare earth elements in synthetic zircon. 1. synthesis, and rare earth element and phosphorus doping.

    SciTech Connect

    Hanchar, J. M.; Finch, R. J.; Hoskin, W. O.; Watson, E. B.; Cherniak, D. J.; Mariano, A. N.; Chemical Engineering; George Washington Univ.; Univ. of Canterbury; Australian National Univ.; Rensselaer Polytechnic Inst.

    2001-05-01

    Sedimentary mineral assemblages commonly contain detrital zircon crystals as part of the heavy-mineral fraction. Age spectra determined by U-Pb isotopic analysis of single zircon crystals within a sample may directly image the age composition--but not the chemical composition--of the source region. Rare earth element (REE) abundances have been measured for zircons from a range of common crustal igneous rock types from different tectonic environments, as well as kimberlite, carbonatite, and high-grade metamorphic rocks, to assess the potential of using zircon REE characteristics to infer the rock types present in sediment source regions. Except for zircon with probable mantle affinities, zircon REE abundances and normalized patterns show little intersample and intrasample variation. To evaluate the actual variation in detrital zircon REE composition in a true sediment of known mixed provenance, zircons from a sandstone sample from the Statfjord Formation (North Sea) were analyzed. Despite a provenance including high-grade metasediment and granitoids and a range in zircon age of 2.82 b.y., the zircon REEs exhibit a narrow abundance range with no systematic differences in pattern shape. These evidences show zircon REE patterns and abundances are generally not useful as indicators of provenance.

  10. Geology: The Active Earth.

    ERIC Educational Resources Information Center

    Braus, Judy, Ed.

    1987-01-01

    Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. The topic of this issue is "Geology: The Active Earth." Contents are organized into the…

  11. Instability of some divalent rare earth ions and photochromic effect

    NASA Astrophysics Data System (ADS)

    Egranov, A. V.; Sizova, T. Yu.; Shendrik, R. Yu.; Smirnova, N. A.

    2016-03-01

    It was shown that the divalent rare earth ions (La, Ce, Gd, Tb, Lu, and Y) in cubic sites in alkaline earth fluorides are unstable with respect to electron autodetachment since its d1(eg) ground state is located in the conduction band which is consistent with the general tendency of these ions in various compounds. The localization of doubly degenerate d1(eg) level in the conduction band creates a configuration instability around the divalent rare earth ion that leading to the formation of anion vacancy in the nearest neighborhood, as was reported in the previous paper [A. Egranov, T. Sizova, Configurational instability at the excited impurity ions in alkaline earth fluorites, J. Phys. Chem. Solids 74 (2013) 530-534]. Thus, the formation of the stable divalent ions as La, Ce, Gd, Tb, Lu, and Y (PC+ centers) in CaF2 and SrF2 crystals during x-ray irradiation occurs via the formation of charged anion vacancies near divalent ions (Re2+va), which lower the ground state of the divalent ion relative to the conductivity band. Photochromic effect occurs under thermally or optically stimulated electron transition from the divalent rare earth ion to the neighboring anion vacancy and reverse under ultraviolet light irradiation. It is shown that the optical absorption of the PC+ centers due to d → d and d → f transitions of the divalent rare-earth ion.

  12. Physical and electrochemical properties of alkaline earth doped, rare earth vanadates

    SciTech Connect

    Adijanto, Lawrence; Balaji Padmanabhan, Venu; Holmes, Kevin J.; Gorte, Raymond J.; Vohs, John M.

    2012-06-15

    The effect of partial substitution of alkaline earth (AE) ions, Sr{sup 2+} and Ca{sup 2+}, for the rare earth (RE) ions, La{sup 3+}, Ce{sup 3+}, Pr{sup 3+}, and Sm{sup 3+}, on the physical properties of REVO{sub 4} compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO{sub 4}-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H{sub 2} fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode. - Graphical abstract: Coulometric titration isotherms for ({open_square}) LaVO{sub 4}, ( White-Circle ) PrVO{sub 4}, ( Lozenge ) CeVO{sub 4}, ( Black-Up-Pointing-Triangle ) Ce{sub 0.7}Sr{sub 0.3}VO{sub 3.85}, and ( Black-Square ) Ce{sub 0.7}Ca{sub 0.3}VO{sub 3.85}, at 973 K. Highlights: Black-Right-Pointing-Pointer Infiltration procedures were used to prepare SOFC anodes from various vanadates. Black-Right-Pointing-Pointer Doping of Alkaline Earth to Rare Earth Vanadates showed to improve conductivity and chemical stability. Black-Right-Pointing-Pointer Alkaline Earth Doped Rare Earth Vanadates-YSZ composites showed conductivities as high as 5 S cm{sup -1} at 973 K. Black-Right-Pointing-Pointer As with other ceramic anodes, the addition of a catalyst was required to achieve low anode impedance.

  13. Refining and Mutual Separation of Rare Earths Using Biomass Wastes

    NASA Astrophysics Data System (ADS)

    Inoue, Katsutoshi; Alam, Shafiq

    2013-10-01

    Two different types of adsorption gels were prepared from biomass wastes. The first gel was produced from astringent persimmon peel rich in persimmon tannin, a polyphenol compound, which was prepared by means of simple dehydration condensation reaction using concentrated sulfuric acid for crosslinking. This adsorption gel was intended to be employed for the removal of radioactive elements, uranium (U(VI)) and thorium (Th(IV)), from rare earths. The second gel was prepared from chitosan, a basic polysaccharide, produced from shells of crustaceans such as crabs, shrimps, prawns, and other biomass wastes generated in marine product industry, by immobilizing functional groups of complexanes such as ethylendiaminetetraacetic acid and diethylentriaminepentaacetic acid (DTPA). This gel was developed for the mutual separation of rare earths. Of the two adsorption gels evaluated, the DTPA immobilized chitosan exhibited the most effective mutual separation among light rare earths.

  14. High efficiency rare-earth emitter for thermophotovoltaic applications

    SciTech Connect

    Sakr, E. S.; Zhou, Z.; Bermel, P.

    2014-09-15

    In this work, we propose a rare-earth-based ceramic thermal emitter design that can boost thermophotovoltaic (TPV) efficiencies significantly without cold-side filters at a temperature of 1573 K (1300 °C). The proposed emitter enhances a naturally occurring rare earth transition using quality-factor matching, with a quarter-wave stack as a highly reflective back mirror, while suppressing parasitic losses via exponential chirping of a multilayer reflector transmitting only at short wavelengths. This allows the emissivity to approach the blackbody limit for wavelengths overlapping with the absorption peak of the rare-earth material, while effectively reducing the losses associated with undesirable long-wavelength emission. We obtain TPV efficiencies of 34% using this layered design, which only requires modest index contrast, making it particularly amenable to fabrication via a wide variety of techniques, including sputtering, spin-coating, and plasma-enhanced chemical vapor deposition.

  15. Laminated rare earth structure and method of making

    DOEpatents

    Senor, David J [West Richland, WA; Johnson, Roger N [Richland, WA; Reid, Bruce D [Pasco, WA; Larson, Sandra [Richland, WA

    2002-07-30

    A laminated structure having two or more layers, wherein at least one layer is a metal substrate and at least one other layer is a coating comprising at least one rare earth element. For structures having more than two layers, the coating and metal substrate layers alternate. In one embodiment of the invention, the structure is a two-layer laminate having a rare earth coating electrospark deposited onto a metal substrate. In another embodiment of the invention, the structure is a three-layer laminate having the rare earth coating electrospark deposited onto a first metal substrate and the coating subsequently abonded to a second metal substrate. The bonding of the coating to the second metal substrate may be accomplished by hot pressing, hot rolling, high deformation rate processing, or combinations thereof. The laminated structure may be used in nuclear components where reactivity control or neutron absorption is desired and in non-nuclear applications such as magnetic and superconducting films.

  16. Method for treating rare earth-transition metal scrap

    DOEpatents

    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.

  17. Yttrium and rare earth stabilized fast reactor metal fuel

    DOEpatents

    Guon, Jerold; Grantham, LeRoy F.; Specht, Eugene R.

    1992-01-01

    To increase the operating temperature of a reactor, the melting point and mechanical properties of the fuel must be increased. For an actinide-rich fuel, yttrium, lanthanum and/or rare earth elements can be added, as stabilizers, to uranium and plutonium and/or a mixture of other actinides to raise the melting point of the fuel and improve its mechanical properties. Since only about 1% of the actinide fuel may be yttrium, lanthanum, or a rare earth element, the neutron penalty is low, the reactor core size can be reduced, the fuel can be burned efficiently, reprocessing requirements are reduced, and the nuclear waste disposal volumes reduced. A further advantage occurs when yttrium, lanthanum, and/or other rare earth elements are exposed to radiation in a reactor, they produce only short half life radioisotopes, which reduce nuclear waste disposal problems through much shorter assured-isolation requirements.

  18. Method for treating rare earth-transition metal scrap

    DOEpatents

    Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.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 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. 3 figs.

  19. Luminescent properties of Tb-activated rare-earth oxyapatite silicate MLn4Si3O13 (M = Ca, Sr, Ln = La, Gd)

    NASA Astrophysics Data System (ADS)

    Yamane, A.; Kunimoto, T.; Ohmi, K.; Honma, T.; Kobayashi, H.

    2006-09-01

    Rare-earth oxyapatites MLn4Si3O13 (M = Ca, Sr, Ba Ln = La, Gd) have been proposed as a new plasma display panel (PDP) host material to overcome the problems of Zn2SiO4:Mn commercial green phosphor, such as luminance degradation and poor surface charge. Tb-doped MLn4Si3O13 phosphor powders show a green luminescence with the CIE color coordinate (x, y) = (0.337, 0.562). The PL excitation band lies continuously in the wavelength region from 130 to 260 nm. The photoluminescence (PL) peak intensity of SrGd4Si3O13:Tb is comparable with that of Zn2SiO4:Mn. The phosphor is a candidate for a green PDP phosphor for Xe2 excitation.

  20. Dynamics of dipolar defects in rare earth-doped alkaline-earth fluoride crystals

    NASA Astrophysics Data System (ADS)

    Charnock, Forrest Taylor

    Alkaline-earth fluoride crystals such as SrF2 provide an excellent sample material for investigating the physics of point defects in crystal lattices. High quality crystals are easily grown, and they readily accept many dopant ions into the lattice, particularly rare earth ions. Rare earth dopant ions (typically trivalent) occupy substitutional sites in the lattice by replacing a Sr2+ ion. Due to the extra charge of the rare earth ion, charge compensation is often provided by an extra fluoride ion (F--) located in a nearby interstitial position. If located in the nearest-neighbor (nn) interstitial position, it forms a defect with C4n symmetry; if located in the next-nearest-neighbor (nnn) intersitial position, it forms a defect with C3n symmetry. Given sufficient thermal energy, this interstitial F ion can move to adjacent interstitial sites and hence reorient the defect. The rate w at which the ion moves from one interstitial site to another is well described by a simple Arrhenius expression: w=n0e-E/kT , where n0 is the attack frequency of the F-- and E is the activation energy. This motion can profoundly affect both the electronic polarizability of the material and the polarization of light emitted or absorbed by the rare earth ion. This thesis describes the normal mode motion of interstitial ions which may occupy either nn or nnn interstitial sites. Using electron paramagnetic resonance (EPR), I observed the relative populations of nn and nnn defects in SrF2 doped with Gd3+ as a function of temperature. These measurements show that dipolar reorientation of the nnn F occurs through the nn interstitial position. Not all interstitial F-- motion is thermally driven. Fluorescence depolarization measurements of SrF2:Pr3+ indicate that optically stimulating a Pr3+ may induce interstitial motion of a nn F--. Such motion was confirmed by showing that nn defects in SrF2:Pr3+ may be polarized at very low temperatures when the sample is illuminated with resonant light. I

  1. Process to remove rare earth from IFR electrolyte

    DOEpatents

    Ackerman, J.P.; Johnson, T.R.

    1992-01-01

    The invention is a process for the removal of rare earths from molten chloride electrolyte salts used in the reprocessing of integrated fast reactor fuel (IFR). The process can be used either continuously during normal operation of the electrorefiner or as a batch process. The process consists of first separating the actinide values from the salt before purification by removal of the rare earths. After replacement of the actinides removed in the first step, the now-purified salt electrolyte has the same uranium and plutonium concentration and ratio as when the salt was removed from the electrorefiner.

  2. Process to remove rare earth from IFR electrolyte

    DOEpatents

    Ackerman, J.P.; Johnson, T.R.

    1994-08-09

    The invention is a process for the removal of rare earths from molten chloride electrolyte salts used in the reprocessing of integrated fast reactor fuel (IFR). The process can be used either continuously during normal operation of the electrorefiner or as a batch process. The process consists of first separating the actinide values from the salt before purification by removal of the rare earths. After replacement of the actinides removed in the first step, the now-purified salt electrolyte has the same uranium and plutonium concentration and ratio as when the salt was removed from the electrorefiner. 1 fig.

  3. Rare earth-transition metal scrap treatment method

    DOEpatents

    Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.; Lincoln, L.P.

    1992-02-11

    Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. 3 figs.

  4. Rare earth-transition metal scrap treatment method

    DOEpatents

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

    1992-02-11

    Rare earth-transition metal (e.g. iron) scrap (e.g. Nd-Fe-B scrap) is melted to reduce the levels of tramp oxygen and nitrogen impurities therein. The tramp impurities are reduced in the melt by virtue of the reaction of the tramp impurities and the rare earth to form dross on the melt. The purified melt is separated from the dross for reuse. The oxygen and nitrogen of the melt are reduced to levels acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets.

  5. Thermal Expansion and Thermal Conductivity of Rare Earth Silicates

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Lee, Kang N.; Bansal, Narottam P.

    2006-01-01

    Rare earth silicates are considered promising candidate materials for environmental barrier coatings applications at elevated temperature for ceramic matrix composites. High temperature thermophysical properties are of great importance for coating system design and development. In this study, the thermal expansion and thermal conductivity of hot-pressed rare earth silicate materials were characterized at temperatures up to 1400 C. The effects of specimen porosity, composition and microstructure on the properties were also investigated. The materials processing and testing issues affecting the measurements will also be discussed.

  6. THE RARE EARTH PEAK: AN OVERLOOKED r-PROCESS DIAGNOSTIC

    SciTech Connect

    Mumpower, Matthew R.; McLaughlin, G. C.; Surman, Rebecca E-mail: gail_mclaughlin@ncsu.edu

    2012-06-20

    The astrophysical site or sites responsible for the r-process of nucleosynthesis still remains an enigma. Since the rare earth region is formed in the latter stages of the r-process, it provides a unique probe of the astrophysical conditions during which the r-process takes place. We use features of a successful rare earth region in the context of a high-entropy r-process (S {approx}> 100k{sub B} ) and discuss the types of astrophysical conditions that produce abundance patterns that best match meteoritic and observational data. Despite uncertainties in nuclear physics input, this method effectively constrains astrophysical conditions.

  7. Dinuclear rare-earth metal alkyl complexes supported by indolyl ligands in μ-η(2) :η(1) :η(1) hapticities and their high catalytic activity for isoprene 1,4-cis-polymerization.

    PubMed

    Zhang, Guangchao; Wei, Yun; Guo, Liping; Zhu, Xiancui; Wang, Shaowu; Zhou, Shuangliu; Mu, Xiaolong

    2015-02-02

    Two series of new dinuclear rare-earth metal alkyl complexes supported by indolyl ligands in novel μ-η(2) :η(1) :η(1) hapticities are synthesized and characterized. Treatment of [RE(CH2 SiMe3 )3 (thf)2 ] with 1 equivalent of 3-(tBuN=CH)C8 H5 NH (L1 ) in THF gives the dinuclear rare-earth metal alkyl complexes trans-[(μ-η(2) :η(1) :η(1) -3-{tBuNCH(CH2 SiMe3 )}Ind)RE(thf)(CH2 SiMe3 )]2 (Ind=indolyl, RE=Y, Dy, or Yb) in good yields. In the process, the indole unit of L1 is deprotonated by the metal alkyl species and the imino C=N group is transferred to the amido group by alkyl CH2 SiMe3 insertion, affording a new dianionic ligand that bridges two metal alkyl units in μ-η(2) :η(1) :η(1) bonding modes, forming the dinuclear rare-earth metal alkyl complexes. When L1 is reduced to 3-(tBuNHCH2 )C8 H5 NH (L2 ), the reaction of [Yb(CH2 SiMe3 )3 (thf)2 ] with 1 equivalent of L2 in THF, interestingly, generated the trans-[(μ-η(2) :η(1) :η(1) -3-{tBuNCH2 }Ind)Yb(thf)(CH2 SiMe3 )]2 (major) and cis-[(μ-η(2) :η(1) :η(1) -3-{tBuNCH2 }Ind)Yb(thf)(CH2 SiMe3 )]2 (minor) complexes. The catalytic activities of these dinuclear rare-earth metal alkyl complexes for isoprene polymerization were investigated; the yttrium and dysprosium complexes exhibited high catalytic activities and high regio- and stereoselectivities for isoprene 1,4-cis-polymerization.

  8. Magnetic Nanofluid Rare Earth Element Extraction Process Report, Techno Economic Analysis, and Results for Geothermal Fluids

    SciTech Connect

    Pete McGrail

    2016-03-14

    This GDR submission is an interim technical report and raw data files from the first year of testing on functionalized nanoparticles for rare earth element extraction from geothermal fluids. The report contains Rare Earth Element uptake results (percent removal, mg Rare Earth Element/gram of sorbent, distribution coefficient) for the elements of Neodymium, Europium, Yttrium, Dysprosium, and Cesium. A detailed techno economic analysis is also presented in the report for a scaled up geothermal rare earth element extraction process. All rare earth element uptake testing was done on simulated geothermal brines with one rare earth element in each brine. The rare earth element uptake testing was conducted at room temperature.

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

    PubMed

    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.

  10. Radioluminescence and thermoluminescence of rare earth element and phosphorus-doped zircon

    SciTech Connect

    Karali, T.; Can, N.; Townsend, P.D.; Rowlands, A.P.; Hanchar, J.M.

    2000-06-01

    The radioluminescence and thermoluminescence spectra of synthetic zircon crystals doped with individual trivalent rare earth element (REE) ions (Pr, Sm, Eu, Gd, Dy, Ho, Er, and Yb) and P are reported in the temperature range 25 to 673 K. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE{sup 3+} states. The shapes of the glow curves are different for each dopant, and there are distinct differences between glow peak temperatures for different rare-earth lines of the same element. Within the overall set of signals there are indications of linear trends in which some glow peak temperatures vary as a function of the ionic size of the rare earth ions. The temperature shifts of the peaks are considerable, up to 200{degree}, and much larger than those cited in other rare-earth-doped crystals of LaF{sub 3} and Bi{sub 4}Ge{sub 3}O{sub 12}. The data clearly suggest that the rare-earth ions are active both in the trapping and luminescence steps, and hence the TL occurs within localized defect complexes that include REE{sup 3+} ions.

  11. Determination of thorium and of rare earth elements in cerium earth minerals and ores

    USGS Publications Warehouse

    Carron, M.K.; Skinner, D.L.; Stevens, R.E.

    1955-01-01

    The conventional oxalate method for precipitating thorium and the rare earth elements in acid solution exhibits definite solubilities of these elements. The present work was undertaken to establish conditions overcoming these solubilities and to find optimum conditions for precipitating thorium and the rare earth elements as hydroxides and sebacates. The investigations resulted in a reliable procedure applicable to samples in which the cerium group elements predominate. The oxalate precipitations are made from homogeneous solution at pH 2 by adding a prepared solution of anhydrous oxalic acid in methanol instead of the more expensive crystalline methyl oxalate. Calcium is added as a carrier. Quantitative precipitation of thorium and the rare earth elements is ascertained by further small additions of calcium to the supernatant liquid, until the added calcium precipitates as oxalate within 2 minutes. Calcium is removed by precipitating the hydroxides of thorium and rare earths at room temperature by adding ammonium hydroxide to pH > 10. Thorium is separated as the sebacate at pH 2.5, and the rare earths are precipitated with ammonium sebacate at pH 9. Maximum errors for combined weights of thorium and rare earth oxides on synthetic mixtures are ??0.6 mg. Maximum error for separated thoria is ??0.5 mg.

  12. The Active Solid Earth

    NASA Astrophysics Data System (ADS)

    Ebinger, Cynthia

    2016-04-01

    Dynamic processes in Earth's crust, mantle and core shape Earth's surface and magnetic field over time scales of seconds to millennia, and even longer time scales as recorded in the ca. 4 Ga rock record. Our focus is the earthquake-volcano deformation cycles that occur over human time scales, and their comparison with time-averaged deformation studies, with emphasis on mantle plume provinces where magma and volatile release and vertical tectonics are readily detectable. Active deformation processes at continental and oceanic rift and back arc zones provide critical constraints on mantle dynamics, the role of fluids (volatiles, magma, water), and plate rheology. For example, recent studies of the East African rift zone, which formed above one of Earth's largest mantle upwellings reveal that magma production and volatile release rates are comparable to those of magmatic arcs, the archetypal zones of continental crustal creation. Finite-length faults achieve some plate deformation, but magma intrusion in the form of dikes accommodates extension in continental, back-arc, and oceanic rifts, and intrusion as sills causes permanent uplift that modulates the local time-space scales of earthquakes and volcanoes. Volatile release from magma intrusion may reduce fault friction and permeability, facilitating aseismic slip and creating magma pathways. We explore the implications of active deformation studies to models of the time-averaged structure of plume and extensional provinces in continental and oceanic plate settings.

  13. Thin Films of the Rare-Earth Metals,

    DTIC Science & Technology

    A vacuum thermal method of producing thin films (1-10 mu m) of rare earth metals (Sm, Dy, Tn, and Yb) is described and its efficiency is compared with...existing methods (which are briefly reviewed). A very effective method of obtaining the thin films in question is by reducing the corresponding

  14. Electrical Relaxation in Rare Earth Doped Cubic Lead Fluoride.

    DTIC Science & Technology

    1982-11-01

    PAGE (W v,. Data Fleted ) READ INSTRUCTIONSREPORT DOCUMENTATION PAGE BEFRE CMPETINGFORSORE OMPLETIN FO M 1. REPORT NUMBER j2. GOVT ACCESSION NO. 3...For the smallest rare earths, however, at least nine .* relaxations are found. The concentration studies indicate multiple relaxations for certain...relaxations are found. The concentration studies indicate multiple relaxations for certain sites. Both simple sites and clusters are observed for

  15. Potential synergy: the thorium fuel cycle and rare earths processing

    SciTech Connect

    Ault, T.; Wymer, R.; Croff, A.; Krahn, S.

    2013-07-01

    The use of thorium in nuclear power programs has been evaluated on a recurring basis. A concern often raised is the lack of 'thorium infrastructure'; however, for at least a part of a potential thorium fuel cycle, this may less of a problem than previously thought. Thorium is frequently encountered in association with rare earth elements and, since the U.S. last systematically evaluated the large-scale use of thorium (the 1970's,) the use of rare earth elements has increased ten-fold to approximately 200,000 metric tons per year. Integration of thorium extraction with rare earth processing has been previously described and top-level estimates have been done on thorium resource availability; however, since ores and mining operations differ markedly, what is needed is process flowsheet analysis to determine whether a specific mining operation can feasibly produce thorium as a by-product. Also, the collocation of thorium with rare earths means that, even if a thorium product stream is not developed, its presence in mining waste streams needs to be addressed and there are previous instances where this has caused issues. This study analyzes several operational mines, estimates the mines' ability to produce a thorium by-product stream, and discusses some waste management implications of recovering thorium. (authors)

  16. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium.

  17. Pitfalls of rare earth imaging: conquering the three Ps.

    PubMed

    Lam, R W; Price, S C

    1992-01-01

    Rare earth technology has become the standard in radiographic imaging, but misapplication and insufficient comprehension of the variables of usage create practical problems. Special problem areas are pediatrics, portable radiography and phototimed exposures. These problems, as well as possible solutions, are addressed in this article.

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

    USGS Publications Warehouse

    Jackson, W.D.; Christiansen, Grey

    1993-01-01

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

  19. Optically active homoleptic bis(phthalocyaninato) rare earth double-decker complexes bearing peripheral chiral menthol moieties: effect of pi-pi interaction on the chiral information transfer at the molecular level.

    PubMed

    Lv, Wei; Zhu, Peihua; Bian, Yongzhong; Ma, Changqin; Zhang, Xiaomei; Jiang, Jianzhuang

    2010-07-19

    With the view to creating novel sandwich-type phthalocyaninato rare earth complexes toward new applications in material science and catalysis, d- and l-enantiomers of a series of optically active homoleptic bis(phthalocyaninato) rare earth double-deckers with four chiral menthol moieties at the peripheral positions of the phthalocyanine ligand, M(Pc*)(2) [Pc* = 2(3),9(10),16(17),23(24)-tetrakis(2-isopropyl-5-methylcyclohexoxyl)phthalocyanine; M = Eu, Y, Lu] (1-3), have been designed and prepared by treating (d)- or (l)-4-(2-isopropyl-5-methylcyclohexoxyl)-1,2-dicyanobenzene with the corresponding M(acac)(3).nH(2)O (acac = acetylacetonate) in the presence of the organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-pentanol. For the purpose of comparative study, heteroleptic bis(phthalocyaninato) europium analogues (d)- and (l)-Eu(Pc)(Pc*) (4) as well as the unsubstituted homoleptic bis(phthalocyaninato) europium counterpart Eu(Pc)(2) (5) were also prepared. The novel synthesized bis(phthalocyaninato) rare earth double-deckers have been characterized by a wide range of spectroscopic methods including MS, (1)H NMR, IR, and electronic absorption spectroscopic measurements in addition to elemental analysis. In contrast to the CD silent monomeric metal-free 2(3),9(10),16(17),23(24)-tetrakis(2-isopropyl-5-methylcyclohexoxyl)phthalocyanine, observation of the CD signal in the N absorption region of 4 reveals the significant effect of intramolecular pi-pi interaction on intensifying the asymmetrical perturbation of the chiral menthol units onto the phthalocyanine chromophore, which results in successful chiral information transfer from menthol moieties to the phthalocyanine chromophore at a molecular level in the heteroleptic double-decker compound 4 despite the lack of CD signal in the Soret and Q absorption regions of the phthalocyanine ligand. This is further supported by the optical activity of homoleptic bis(phthalocyaninato) rare earth double-deckers M

  20. Effects of simulated rare earth recycling wastewaters on biological nitrification

    DOE PAGES

    Fujita, Yoshiko; Barnes, Joni; Eslamimanesh, Ali; ...

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N.more » europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.« less

  1. Effects of simulated rare earth recycling wastewaters on biological nitrification

    SciTech Connect

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

    2015-07-16

    Current efforts to increase domestic availability of rare-earth element (REE) supplies by recycling and expanded ore processing efforts will result in increased generation of associated wastewaters. In some cases disposal to a sewage treatment plant may be favored but plant performance must be maintained. To assess the potential effects of such wastewaters on biological wastewater treatment, model nitrifying organisms Nitrosomonas europaea and Nitrobacter winogradskyi were exposed to simulated wastewaters containing varying levels of yttrium or europium (10, 50 and 100 ppm), and the REE extractant tributyl phosphate (TBP, at 0.1 g/L). Y and Eu additions above 10 ppm inhibited N. europaea activity, even when initially virtually all of the REE was insoluble. The provision of TBP together with Eu increased inhibition of nitrite production by the N. europaea, although TBP alone did not substantially alter nitrifying activity N. winogradskyi was more sensitive to the stimulated wastewaters, with even 10 ppm Eu or Y inducing significant inhibition, and a complete shutdown of nitrifying activity occurred in the presence of the TBP. To analyze the availability of REEs in aqueous solutions, REE solubility has been calculated using the previously developed MSE (Mixed-Solvent Electrolyte) thermodynamic model. The model calculations reveal a strong pH dependence of solubility, which is typically controlled by the precipitation of REE hydroxides but may also be influenced by the formation of a phosphate phase.

  2. Visible light induced oxidation of water by rare earth manganites, cobaltites and related oxides

    NASA Astrophysics Data System (ADS)

    Naidu, B. S.; Gupta, Uttam; Maitra, Urmimala; Rao, C. N. R.

    2014-01-01

    A study of the visible light induced oxidation of water by perovskite oxides of the formula LaMO3 (M = transition metal) has revealed the best activity with LaCoO3 which contains Co3+ in the intermediate-spin (IS) with one eg electron. Among the rare earth manganites, only orthorhombic manganites with octahedral Mn3+ ions exhibit good catalytic activity, but hexagonal manganites are poor catalysts. Interestingly, not only the perovskite rare earth cobaltites but also solid solutions of Co3+ in cubic rare earth sesquioxides exhibit catalytic activity comparable to LaCoO3, the Co3+ ion in all these oxides also being in the IS t2g5 e g 1 state.

  3. [FUNCTIONAL ACTIVITY OF EHRLICH CARCINOMA CELLS AFTER TREATMENT WITH HYBRID NANOCOMPLEXES CONTAINING ORTHOVANADATES OF RARE-EARTH ELEMENTS, CHOLESTEROL AND LUMINESCENT DYE].

    PubMed

    Goltsev, A N; Babenko, N N; Gaevskaya, A; Chelombitko, O V; Bondarovich, N A; Dubrava, T G; Ostankov, M V; Klochkov, V K; Kavok, N S; Malyukin, Yu V

    2015-01-01

    Tumor development is the consequence of expanding the population of low differentiated cells with unlimited self-maintenance potential, i.e. cancer stem cells (CSCs). Application of new forms of nanocomposites capable of binding to CSCs and inducing the tumor destruction is perspective direction for treating this pathology. There have been developed the methods of obtaining hybrid nanocomplexes containing rare-earth orthovanadates GdYVO4:Eu³⁺, cholesterol and luminescent dye Dil. By immune fluorescence method using monoclonal antibodies to CD44, CD24, CD117 and Sca-1 markers there has been established the change in the ratio of tumor progenitors of various differentiation levels in a general pool of Ehrlich carcinoma (EC) after treatment with hybrid nanocomplexes. Essential reduction in the concentration of the most tumorogenic CD44high cells with simultaneous rise in the number of CD117⁺-cells resulted in an increased index of CD44high/CD117⁺ ratio. It has been demonstrated that application of hybrid nanocomplexes suppressed the tumor growth almost by 80%. The value of cooperative interactions of the cells with different phenotype signs in tumor sites has been proved. The index of CD44high/CD117⁺ ratio can be used as one of diagnostic and prognostic parameters of development and inactivation rate of tumor process when using different types of anti-tumor therapy.

  4. Photoluminescence properties of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) activated NaInW{sub 2}O{sub 8} wolframite host lattice

    SciTech Connect

    Asiri Naidu, S.; Boudin, S.; Varadaraju, U.V.; Raveau, B.

    2012-01-15

    The photoluminescence (PL) studies on NaIn{sub 1-x}RE{sub x}W{sub 2}O{sub 8}, with RE=Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+} phases have shown that the relative contribution of the host lattice and of the intra-f-f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy{sup 3+} and Tm{sup 3+} activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu{sup 3+}, with intense red emission, the host absorption is less pronounced and the intra-f-f transitions of the Eu{sup 3+} ions play a major role, whereas for Tb{sup 3+} intra-f-f transitions are only observed, giving rise to green emission. - Graphical abstract: NaInW{sub 2}O{sub 8} double tungstate doped with Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}and Tm{sup 3+} shows characteristic emission of intense red for Eu{sup 3+}, yellow for Dy{sup 3+}, green for Tb{sup 3+} and blue for Tm{sup 3+}. Highlights: Black-Right-Pointing-Pointer Characteristic emissions of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) are observed NaInW{sub 2}O{sub 8} wolframite. Black-Right-Pointing-Pointer Energy transfer from host to the activators (Eu{sup 3+} Dy{sup 3+} Tm{sup 3+} is observed. Black-Right-Pointing-Pointer PL properties of rare earth ions depend on minor structural variations in the host lattice.

  5. Half-sandwich rare-earth-catalyzed olefin polymerization, carbometalation, and hydroarylation.

    PubMed

    Nishiura, Masayoshi; Guo, Fang; Hou, Zhaomin

    2015-08-18

    -site catalysts. This Account is intended to give an overview of our recent studies on organo rare-earth catalysis, in particular the synthesis and application of half-sandwich rare-earth alkyl complexes bearing monocyclopentadienyl ligands for olefin polymerization, carbometalation, and hydroarylation. Treatment of half-sandwich rare-earth dialkyl complexes having the general formula CpMR2 with an equimolar amount of an appropriate borate compound such as [Ph3C][B(C6F5)4] can generate the corresponding cationic monoalkyl species, which serve as excellent single-site catalysts for the polymerization and copolymerization of a wide range of olefin monomers such as ethylene, 1-hexene, styrene, conjugated and nonconjugated dienes, and cyclic olefins. The cationic half-sandwich rare-earth alkyl complexes can also catalyze the regio- and stereoselective alkylative alumination of alkenes and alkynes through insertion of the unsaturated C-C bond into the metal-alkyl bond followed by transmetalation between the resulting new alkyl or alkenyl species and an alkylaluminum compound. Moreover, a combination of deprotonative C-H bond activation of appropriate organic compounds such as anisoles and pyridines by the rare-earth alkyl species and insertion of alkenes into the resulting new metal-carbon bond can lead to catalytic C-H bond alkylation of the organic substrates. Most of these transformations are unique to the rare-earth catalysts with selectivity and functional group tolerance different from those of late-transition-metal catalysts.

  6. Systematic variation of rare-earth elements in cerium-earth minerals

    USGS Publications Warehouse

    Murata, K.J.; Rose, H.J.; Carron, M.K.; Glass, J.J.

    1957-01-01

    In a continuation of a study reported previously, rare-earth elements and thorium have been determined in monazite, allanite, cerite, bastnaesite, and a number of miscellaneous cerium-earth minerals. A quantity called sigma (???), which is the sum of the atomic percentages of La, Ce, and Pr, is proposed as an index of composition of all cerium-earth minerals with respect to the rare-earth elements. The value of ??? for all of the minerals analysed falls between 58 and 92 atomic per cent. Monazites, allanites, and cerites cover the entire observed range, whereas bastnaesites are sharply restricted to the range between 80 and 92 atomic per cent. The minimum value of ??? for a cerium-earth mineral corresponds to the smallest possible unit-cell size of the mineral. In monazite, this structurally controlled minimum value of ??? is estimated to be around 30 atomic per cent. Neodymium, because of its abundance, and yttrium, because of its small size, have dominant roles in contraction of the structure. In the other direction, the limit of variation in composition will be reached when lanthanum becomes the sole rare-earth element in a cerium-earth mineral. Cerium-earth minerals from alkalic rocks are all characterized by values of ??? greater than 80 atomic per cent, indicating that the processes that formed these rocks were unusually efficient in fractionating the rare-earth elements-efficient in the sense that a highly selected assemblage is produced without eliminating the bulk of these elements. Analyses of inner and outer parts of two large crystals of monazite from different deposits show no difference in ??? in one crystal and a slightly smaller value of ??? in the outer part of the other crystal compared to the inner part. The ??? of monazites from pegmatites that intrude genetically related granitic rocks in North Carolina is found to be either higher or lower than the ??? of monazites in the intruded host rock. These results indicate that the fractionation of the

  7. Active Near Earth Asteroids

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter

    2015-08-01

    Past activity from Near Earth Asteroids is recorded in the meteoroid streams that cause our meteor showers. Automated meteoroid orbit surveys by photographic, low-light video, specular radar, and head-echo radar reflections are providing the first maps of meteor shower activity at different particle sizes. There are distinct differences in particle size distributions among streams. The underlaying mechanisms that created these streams are illuminated: fragmentation from spin-up or thermal stresses, meteoroid ejection by water vapor drag, and ejection of icy particles by CO and CO2 sublimation. The distribution of the meteoroid orbital elements probe the subsequent evolution by planetary perturbations and sample the range of dynamical processes to which Near Earth Asteroids are exposed. The non-stream "sporadic" meteors probe early stages in the evolution from meteoroid streams into the zodiacal dust cloud. We see that the lifetime of large meteoroids is generally not limited by collisions. Results obtained by the CAMS video survey of meteoroid orbits are compared to those from other orbit surveys. Since October 2010, over 200,000 meteoroid orbits have been measured. First results from an expansion into the southern hemisphere are also presented, as are first results from the measurement of main element compositions. Among the many streams detected so far, the Geminid and Sextantid showers stand out by having a relatively high particle density and derive from parent bodies that appear to have originated in the main belt.

  8. The formation of crystals in glasses containing rare earth oxides

    NASA Astrophysics Data System (ADS)

    Fadzil, Syazwani Mohd; Hrma, Pavel; Crum, Jarrod; Siong, Khoo Kok; Ngatiman, Mohammad Fadzlee; Said, Riduan Mt

    2014-02-01

    Korean spent nuclear fuel will reach the capacity of the available temporary storage by 2016. Pyroprocessing and direct disposal seems to be an alternative way to manage and reuse spent nuclear fuel while avoiding the wet reprocessing technology. Pyroprocessing produces several wastes streams, including metals, salts, and rare earths, which must be converted into stabilized form. A suitable form for rare earth immobilization is borosilicate glass. The borosilicate glass form exhibits excellent durability, allows a high waste loading, and is easy to process. In this work, we combined the rare earths waste of composition (in wt%) 39.2Nd2O3-22.7CeO2-11.7La2O3-10.9PrO2-1.3Eu2O3-1.3Gd2O3-8.1Sm2O3-4.8Y2O3 with a baseline glass of composition 60.2SiO2-16.0B2O3-12.6Na2O-3.8Al2O3-5.7CaO-1.7ZrO2. Crystallization in waste glasses occurs as the waste loading increases. It may produce complicate glass processing and affect the product quality. To study crystal formation, we initially made glasses containing 5%, 10% and 15% of La2O3 and then glasses with 5%, 10% and 15% of the complete rare earth mix. Samples were heat-treated for 24 hours at temperatures 800°C to 1150°C in 50°C increments. Quenched samples were analyzed using an optical microscope, scanning electron microscope with energy dispersive spectroscopy, and x-ray diffraction. Stillwellite (LaBSiO5) and oxyapatite (Ca2La8Si6O26) were found in glasses containing La2O3, while oxyapatite (Ca2La8Si6O26 and NaNd9Si6O26) precipitated in glasses with additions of mixed rare earths. The liquidus temperature (TL) of the glasses containing 5%, 10% and 15% La2O3 were 800°C, 959°C and 986°C, respectively; while TL was 825°C, 1059°C and 1267°C for glasses with 5%, 10% and 15% addition of mixed rare earth oxides. The component coefficients TB2O3, TSiO2, TCaO, and TRE2O3 were also evaluated using a recently published study.

  9. Magneto-structural correlations in rare-earth cobalt pnictides

    NASA Astrophysics Data System (ADS)

    Thompson, Corey Mitchell

    Magnetic materials are used in many applications such as credit cards, hard drives, electric motors, sensors, etc. Although a vast range of magnetic solids is available for these purposes, our ability to improve their efficiency and discover new materials remains paramount to the sustainable progress and economic profitability in many technological areas. The search for magnetic solids with improved performance requires fundamental understanding of correlations between the structural, electronic, and magnetic properties of existing materials, as well as active exploratory synthesis that targets the development of new magnets. Some of the strongest permanent magnets, Nd 2Fe14B, SmCo5, and Sm2Co17, combine transition and rare-earth metals, benefiting from the strong exchange between the 4f and 3d magnetic sublattices. Although these materials have been studied in great detail, the development of novel magnets requires thorough investigation of other 3d-4 f intermetallics, in order to gain further insights into correlations between their crystal structures and magnetic properties. Among many types of intermetallic materials, ternary pnictides RCo 2Pn2 (R = La, Ce, Pr, Nd; Pn = P, As) are of interest because, despite their simple crystal structures, they contain two magnetic sublattices, exchange interactions between which may lead to rich and unprecedented magnetic behavior. Nevertheless, magnetism of these materials was studied only to a limited extent, especially as compared to the extensive studies of their silicide and germanide analogues. The ThCr2Si2 structure type, to which these ternary pnictides belong, is one of the most ubiquitous atomic arrangements encountered among intermetallic compounds. It accounts for over 1000 known intermetallics and has received increased attention due to the recently discovered FeAs-based superconductors. This dissertation is devoted to the investigation of

  10. Recent developments of rare-earth-free hard-magnetic materials

    NASA Astrophysics Data System (ADS)

    Li, Da; Pan, DeSheng; Li, ShaoJie; Zhang, ZhiDong

    2016-01-01

    Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the high-performance rare-earth permanent magnets, there is a much revived interest in various types of hard-magnetic materials based on rare-earth-free compounds. The 3d transition metals and their alloys with large coercivity and high Curie temperatures (working temperatures) are expected to overcome the disadvantages of rare-earth magnets. Making rare-earth-free magnets with a large energy product to meet tomorrow's energy needs is still a challenge.

  11. Rare Earth Nanoprobes for Functional Biomolecular Imaging and Theranostics

    PubMed Central

    Naczynski, Dominik J.; Tan, Mei Chee; Riman, Richard E.; Moghe, Prabhas V.

    2014-01-01

    Contrast agents designed to visualize the molecular mechanisms underlying cancer pathogenesis and progression have deepened our understanding of disease complexity and accelerated the development of enhanced drug strategies targeted to specific biochemical pathways. For the next generation probes and imaging systems to be viable, they must exhibit enhanced sensitivity and robust quantitation of morphologic and contrast features, while offering the ability to resolve the disease-specific molecular signatures that may be critical to reconstitute a more comprehensive portrait of pathobiology. This feature article provides an overview on the design and advancements of emerging biomedical optical probes in general and evaluates the promise of rare earth nanoprobes, in particular, for molecular imaging and theranostics. Combined with new breakthroughs in nanoscale probe configurations, and improved dopant compositions, and multimodal infrared optical imaging, rare-earth nanoprobes can be used to address a wide variety of biomedical challenges, including deep tissue imaging, real-time drug delivery tracking and multispectral molecular profiling. PMID:24921049

  12. Electronic and vibrational spectra of some rare earth trifluoromethanesulfonates crystals.

    PubMed

    Paul, P; Ghosh, M; Neogy, D; Mallick, P K

    2011-01-01

    The Raman and infrared spectra of some rare earth (dysprosium and terbium) trifluoromethanesulfonates crystals have been analyzed. Different vibrational frequencies of trifluoromethanesulfonate ions (CF3SO3-) are identified and assigned to different vibrations of the SO3 and CF3 groups. Electronic transitions of R3+ ions (R=Dy, Tb) in these salts have been assigned to transitions from the ground to different energy levels of the ground multiplet. The electronic energy levels of the rare earth ions are also determined theoretically with the help of single electron crystal field theory. They are found to yield results not only in good agreement with the observed spectral data but also in good conformity with those obtained previously from magnetic measurements.

  13. Electronic and vibrational spectra of some rare earth trifluoromethanesulfonates crystals

    NASA Astrophysics Data System (ADS)

    Paul, P.; Ghosh, M.; Neogy, D.; Mallick, P. K.

    2011-01-01

    The Raman and infrared spectra of some rare earth (dysprosium and terbium) trifluoromethanesulfonates crystals have been analyzed. Different vibrational frequencies of trifluoromethanesulfonate ions (CF 3SO 3-) are identified and assigned to different vibrations of the SO 3 and CF 3 groups. Electronic transitions of R 3+ ions (R = Dy, Tb) in these salts have been assigned to transitions from the ground to different energy levels of the ground multiplet. The electronic energy levels of the rare earth ions are also determined theoretically with the help of single electron crystal field theory. They are found to yield results not only in good agreement with the observed spectral data but also in good conformity with those obtained previously from magnetic measurements.

  14. Contamination in the Rare-Earth Element Orthophosphate Reference Samples

    PubMed Central

    Donovan, John J.; Hanchar, John M.; Picolli, Phillip M.; Schrier, Marc D.; Boatner, Lynn A.; Jarosewich, Eugene

    2002-01-01

    Several of the fourteen rare-earth element (plus Sc and Y) orthophosphate standards grown at Oak Ridge National Laboratory in the 1980s and widely distributed by the Smithsonian Institution’s Department of Mineral Sciences, are significantly contaminated by Pb. The origin of this impurity is the Pb2P2O7 flux that is derived from the thermal decomposition of PbHPO4. The lead pyrophosphate flux is used to dissolve the oxide starting materials at elevated temperatures (≈1360 °C) prior to the crystal synthesis. Because these rare-earth element standards are extremely stable under the electron beam and considered homogenous, they have been of enormous value to electron probe micro-analysis (EPMA). The monoclinic, monazite structure, orthophosphates show a higher degree of Pb incorporation than the tetragonal xenotime structure, orthophosphates. This paper will attempt to describe and rationalize the extent of the Pb contamination in these otherwise excellent materials. PMID:27446762

  15. Magnetomigration of rare-earth ions in inhomogeneous magnetic fields.

    PubMed

    Franczak, Agnieszka; Binnemans, Koen; Jan Fransaer

    2016-10-05

    The effects of external inhomogenous (gradient) magnetic fields on the movement of the rare-earth ions: Dy(3+), Gd(3+) and Y(3+), in initially homogeneous aqueous solutions have been investigated. Differences in the migration of rare-earth ions in gradient magnetic fields were observed, depending on the magnetic character of the ions: paramagnetic ions of Dy(3+) and Gd(3+) move towards regions of the sample where the magnetic field gradient is the strongest, while diamagnetic ions of Y(3+) move in the opposite direction. It has been showed that the low magnetic field gradients, such the ones generated by permanent magnets, are sufficient to observe the magnetomigration effects of the ions in solution. The present work clearly establishes the behavior of magnetically different ions in initially homogeneous aqueous solutions exposed to magnetic field gradients. To this avail, a methodology for measuring the local concentration differences of metal ions in liquid samples was developed.

  16. Rare-earth magnet ingestion: a childhood danger reaches adolescence.

    PubMed

    Agha, Beesan Shalabi; Sturm, Jesse J; Costello, Brian E

    2013-10-01

    Ingestion of multiple magnets may cause serious gastrointestinal morbidity, such as pressure necrosis, perforation, fistula formation, or intestinal obstruction due to forceful attraction across bowel wall. Although the consequences of multiple magnet ingestion are well documented in young children, the current popularity of small, powerful rare-earth magnets marketed as "desk toys" has heightened this safety concern in all pediatric age groups. A recent US Consumer Product Safety Commission product-wide warning additionally reports the adolescent practice of using toy high-powered, ball-bearing magnets to simulate tongue and lip piercings, a behavior that may increase risk of inadvertent ingestion. We describe 2 cases of older children (male; aged 10 and 13 years, respectively) with unintentional ingestion of multiple rare-earth magnets. Health care providers should be alerted to the potential for misuse of these high-powered, ball-bearing magnets among older children and adolescents.

  17. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  18. A divalent rare earth oxide semiconductor: Yttrium monoxide

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Rare earth oxides are usually widegap insulators like Y2O3 with closed shell trivalent rare earth ions. In this study, solid phase rock salt structure yttrium monoxide, YO, with unusual valence of Y2+ (4d1) was synthesized in a form of epitaxial thin film by pulsed laser deposition method. YO has been recognized as gaseous phase in previous studies. In contrast with Y2O3, YO was dark-brown colored and narrow gap semiconductor. The tunable electrical conductivity ranging from 10-1 to 103 Ω-1 cm-1 was attributed to the presence of oxygen vacancies serving as electron donor. Weak antilocalization behavior observed in magnetoresistance indicated significant role of spin-orbit coupling as a manifestation of 4d electron carrier.

  19. Rare earths in the Leadville Limestone and its marble derivates

    USGS Publications Warehouse

    Jarvis, J.C.; Wildeman, T.R.; Banks, N.G.

    1975-01-01

    Samples of unaltered and metamorphosed Leadville Limestone (Mississippian, Colorado) were analyzed by neutron activation for ten rare-earth elements (REE). The total abundance of the REE in the least-altered limestone is 4-12 ppm, and their distribution patterns are believed to be dominated by the carbonate minerals. The abundances of the REE in the marbles and their sedimentary precursors are comparable, but the distribution patterns are not. Eu is enriched over the other REE in the marbles, and stratigraphically upward in the formation (samples located progressively further from the heat source), the light REE become less enriched relative to the heavy REE. The Eu anomaly is attributed to its ability, unique among the REE, to change from the 3+ to 2+ oxidation state. Whether this results in preferential mobilization of the other REE or whether this reflects the composition of the pore fluid during metamorphism is unknown. Stratigraphically selective depletion of the heavy REE may be attributed to more competition for the REE between fluid and carbonate minerals in the lower strata relative to the upper strata. This competition could have been caused by changes in the temperature of the pore fluid or to the greater resistance to solution of the dolomite in the lower parts of the formation than the calcite in the upper parts. ?? 1975.

  20. Lunar anorthosites: rare-Earth and other elemental abundances.

    PubMed

    Wakita, H; Schmitt, R A

    1970-11-27

    Elemental abundances of major (Ti, Al, Fe, and Ca), minor (Na, Mn, and Cr), and trace elements [14 rare-earth elements (REE), Y, In, Cd, Rb, Cs, Ba, Co, and Sc] in lunar anorthosites separated from Apollo 11 sample 10085 coarse fines have been determined by means of instrumental and radiochemical neutron activation analysis. The REE distribution pattern of lunar anorthosites, relative to ordinary chondrites, has a positive Eu anomaly. On the assumption that (i) the lunar composition is similar to that of ordinary chondritic meteorites low in total Fe ( approximately 13 percent); (ii) lunar anorthosites are derived from highland cratering events and are representative of the highlands; and (iii) the moon differentiated into olivine, hypersthene, and basaltic and anorthositic phases, and plagioclase crysstallization began after approximately 93 percent solidification, then mass balance calculations yield approximately 30-kilometer and approximately 10-kilometer thicknesses for the lunar highlands for the melting and chemical differentiation of the entire moon and of the upper 200 kilometers, respectively. Corresponding thicknesses of the basaltic basement rocks were approximately 5 kilometers and approximately 2 kilometers, respectively. Alternatively, if the anorthosites of this study are representative of the highlands and the onset of plagioclase crystallization occurred after approximately 50 percent solidification of the initially melted moon, calculations with REE and Ba partition coefficients suggest that the REE and Ba abundances in the primeval moon were similar to those observed in basaltic achondrites.

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

    PubMed

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

    2015-08-18

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

  2. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1990-01-01

    This paper discusses the compositional and phase relationships among minerals in which rare earth elements (REE) occur as essential constituents (e.g., bastnaesite, monazite, xenotime, aeschynite, allanite). Particular consideration is given to the vector representation of complex coupled substitutions in selected REE-bearing minerals and to the REE partitioning between minerals as related to the acid-base tendencies and mineral stabilities. It is shown that the treatment of coupled substitutions as vector quantities facilitates graphical representation of mineral composition spaces.

  3. Temperature-dependent Sellmeier equations for rare-earth sesquioxides.

    PubMed

    Zelmon, David E; Northridge, Jessica M; Haynes, Nicholas D; Perlov, Dan; Petermann, Klaus

    2013-06-01

    High-power lasers are making increasing demands on laser hosts especially in the area of thermal management. Traditional hosts, such as YAG, are unsuitable for many high-power applications and therefore, new hosts are being developed including rare-earth sesquioxides. We report new measurements of the refractive indices of these materials as functions of wavelength and temperature, which will aid in the design of laser cavities and other nonlinear optical elements.

  4. Are rare-earth nanoparticles suitable for in vivo applications?

    PubMed

    Liu, Chunyan; Hou, Yi; Gao, Mingyuan

    2014-10-29

    Rare earth (RE) nanoparticles have attracted considerable attention due to their unique optical and magnetic properties associated with f-electrons. The recent accomplishments in RE nanoparticle synthesis have aroused great interest of scientists to further explore their biomedical applications. This Research News summarizes recent achievements in controlled synthesis of magnetic and luminescent RE nanoparticles, surface modification, and toxicity studies of RE nanomaterials, and highlights state-of-the-art in in vivo applications of RE nanoparticles.

  5. An Integrated Rare Earth Elements Supply Chain Strategy

    DTIC Science & Technology

    2011-02-24

    Disruption in the global supply of rare earths poses a significant concern for America‘s energy security and clean energy objectives, its future defense...World Trade Organization rules by limiting clean energy imports, while incentivizing clean energy exports.54 If accurate, this speculation supports...resource scarcity and secure our supply chains. The NSS further declares the U.S. ―has a window of opportunity to lead in the development of clean energy technology

  6. Magnetostatic Effects in the Nucleation of Rare Earth Ferromagnetic Phases

    SciTech Connect

    Durfee, C. S.; Flynn, C. P.

    2001-07-30

    It has been reported that superheating, supercooling, and explosive kinetics coupled to other degrees of freedom occur at the ferromagnetic transitions of Er and Dy, and that metastable phases occur during the transition kinetics of Er. We explain these observations in terms of magnetostatic energy, which requires highly eccentric nuclei in the homogeneous nucleation of magnetic transitions in heavy rare earths. The magnetostatics favor transitions through ferrimagnetic intermediaries. The unusual kinetics derive from effective spin lattice relaxation.

  7. Distribution coefficients of rare earth ions in cubic zirconium dioxide

    NASA Astrophysics Data System (ADS)

    Romer, H.; Luther, K.-D.; Assmus, W.

    1994-08-01

    Cubic zirconium dioxide crystals are grown with the skull melting technique. The effective distribution coefficients for Nd(exp 3+), Sm(exp 3+) and Er(sup 3+) as dopants are determined experimentally as a function of the crystal growth velocity. With the Burton-Prim-Slichter theory, the equilibrium distribution coefficients can be calculated. The distribution coefficients of all other trivalent rare earth ions can be estimated by applying the correlation towards the ionic radii.

  8. The Synthesis and Characterization of Some Rare Earth Arsenides.

    DTIC Science & Technology

    1987-09-10

    Kobzenko, V. B. Chernogorenko, S. N. L’vov, M. I. Lesnaya, and K. A. Lynchak, "Equilibrium Diagram and Properties of Alloys of the As-Nd System...Stolchiometry and Structure on Physical Properties of the Rare Earth Arsen des .................................... 24 CHAPTER 3 OBJECTIVE AND TECHNICAL...Scanning Calorimetry (DSC) ..... ........ ... .......... . 67 CHAPTER 6 DISCUSSION..... ........... - .... .... . .... .. ..... 71 6.1 Properties of HoAs(Nd

  9. Process for separation of the rare earths by solvent extraction

    DOEpatents

    Mason, George W.; Lewey, Sonia

    1977-04-05

    Production rates for solvent extraction separation of the rare earths and yttrium from each other can be improved by the substitution of di(2-ethylhexyl) mono-thiophosphoric acid for di(2-ethylhexyl) phosphoric acid. The di(2-ethylhexyl) mono-thiophosphoric acid does not form an insoluble polymer at approximately 50% saturation as does the former extractant, permitting higher feed solution concentration and thus greater throughput.

  10. Trade Group Rules Against China in Rare Earths Dispute

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2014-04-01

    The World Trade Organization (WTO) has ruled against China in a trade dispute over rare earth elements (REE) as well as tungsten and molybdenum, the group announced on 26 March. The European Union, Japan, and the United States brought trade cases against China in March 2012 concerning alleged unfair export restraints on the materials (see Eos, 93(13), 134-135, doi:10.1029/2012EO130002).

  11. Trinuclear alkyl hydrido rare-earth complexes supported by amidopyridinato ligands: synthesis, structures, C-Si bond activation and catalytic activity in ethylene polymerization.

    PubMed

    Lyubov, Dmitry M; Cherkasov, Anton V; Fukin, Georgy K; Ketkov, Sergey Yu; Shavyrin, Andrey S; Trifonov, Alexander A

    2014-10-14

    The reaction of Ap(9Me)Lu(CH2SiMe3)2(thf) (Ap(9Me) = (2,4,6-trimethylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) with two molar equivalents of PhSiH3 affords a trinuclear alkyl-hydrido cluster [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2]. The analogous reactions with Ap(9Me)Ln(CH2SiMe3)2(thf) (Ln = Y, Yb) are more complex and result in the formation of mixtures of two types of trinuclear alkyl-hydrido complexes [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiH2Ph)(thf)2] differing in the alkyl group. The DFT calculations of [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] (Ap* = (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridine-2-yl]amido ligand) confirm localization of the HOMO on the Ap*-Y(1A)-CH2SiMe3 fragment, thus explaining its enhanced reactivity. Analysis of the electron density distribution reveals the Y-H and H-H bonding interactions in the (Y)3(μ(2)-H)3(μ(3)-H)2 moiety. The NMR studies of diamagnetic complexes [(Ap(9Me)Lu)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] and [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] demonstrated that the trinuclear cores are retained in the solution and revealed exchange between μ(3)- and μ(2)-bridging hydrido ligands. Complexes [(Ap*Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2], the cationic yttrium hydrido cluster [(Ap*Y)3(μ(2)-H)3(μ(3)-H)2(thf)3](+)[B(C6F5)4](-) as well as [(Ap(9Me)Ln)3(μ(2)-H)3(μ(3)-H)2(CH2SiMe3)(thf)2] proved to be active in catalysis of ethylene polymerization under mild conditions.

  12. Effect of rare earth oxides for improvement of MCFC

    NASA Astrophysics Data System (ADS)

    Ota, Ken-ichiro; Matsuda, Yoshiyuki; Matsuzawa, Koichi; Mitsushima, Shigenori; Kamiya, Nobuyuki

    The solubility of rare earth metal oxides and their effect on the NiO solubility have been discussed to stabilize the cathode of molten carbonate fuel cells. The solubility of Ho, Yb, and Nd oxides were 4.4 × 10 -4, 3.4 × 10 -4, and 1.3 × 10 -3 (mole fraction) at 923 K, respectively. The solubilities of NiO in (Li 0.52/Na 0.48) 2CO 3 with the saturated Ho, Yb, and Nd were 1.57 × 10 -5, 1.41 × 10 -5, and 9.5 × 10 -6, respectively. Among these three, Nd, which has the highest solubility in the carbonates, reduced the NiO solubility most; although, the La reduced the NiO solubility more than Nd. The logarithm of the solubility of the rare earth metal oxides has a linear relation to the Coulomb force ratio between the rare earth metal and the alkaline metal. Following this relation, the La should have the highest solubility among all the lanthanides. The basicity which NiO solubility closely relates has a linear relationship to the Coulomb force parameter of the melts. Based on these two models, the La would be the best additive to reduce the NiO solubility in Li/Na eutectic carbonate melt, among all the lanthanides.

  13. Properties of rare-earth iron garnets from first principles

    NASA Astrophysics Data System (ADS)

    Nakamoto, Ryan; Xu, Bin; Xu, Changsong; Xu, Hu; Bellaiche, L.

    2017-01-01

    Structural and magnetic properties of rare-earth iron garnets (RIG), which contain 160 atoms per unit cell, are systematically investigated for rare-earth elements varying from La to Lu (and including Y), by performing spin polarized density-functional calculations. The effects of 4 f electrons (as core or as valence electrons) on the lattice constant, internal coordinates, and bond lengths are found to be rather small, with these predicted structural properties agreeing rather well with available experiments. On the other hand, treating such electrons as valence electrons is essential to interpret the total magnetization measured in some RIG at low temperature, the different orientation and magnitude of the magnetizations that Fe and rare-earth ions can adopt and to also explain why some RIG have a compensation temperature while others do not. The magnetic exchange couplings and orbital-projected density of states are also reported for two representative materials, namely Gd3Fe5O12 and Nd3Fe5O12 , when accounting for their 4 f electrons.

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

    SciTech Connect

    Skomski, R. Manchanda, P.; Kashyap, A.

    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.

  15. Alternatives to Rare Earth Permanent Magnets for Energy Harvesting Applications

    NASA Astrophysics Data System (ADS)

    Khazdozian, Helena; Hadimani, Ravi; Jiles, David

    Direct-drive permanent magnet generators (DDPMGs) offer increased reliability and efficiency over the more commonly used geared doubly-fed induction generator, yet are only employed in less than 1 percent of utility scale wind turbines in the U.S. One major barrier to increased deployment of DDPMGs in the U.S. wind industry is NdFeB permanent magnets (PMs), which contain critical rare earth elements Nd and Dy. To allow for the use of rare earth free PMs, the magnetic loading, defined as the average magnetic flux density over the rotor surface, must be maintained. Halbach cylinders are employed in 3.5kW Halbach PMGs (HPMGs) of varying slot-to-pole ratio to concentrate the magnetic flux output by a lower energy density PM over the rotor surface. We found that for high pole and slot number, the increase in magnetic loading is sufficient to allow for the use of strontium iron oxide hard ferrite PMs and achieved rated performance. Joule losses in the stator windings were found to increase for the hard ferrite PMs due to increased inductance in the stator windings. However, for scaling of the HPMG designs to 3MW, rated performance and high efficiency were achieved, demonstrating the potential for elimination for rare earth PMs in commercial scale wind turbines. This work was supported by the National Science Foundation under Grant No. 1069283 and a Barbara and James Palmer Endowment at Iowa State University.

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

    PubMed

    Du, Xiaoyue; Graedel, T E

    2013-09-01

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

  17. Magnetism of perovskite cobaltites with Kramers rare-earth ions

    SciTech Connect

    Jirák, Z. Hejtmánek, J.; Knížek, K.; Novák, P.; Šantavá, E.; Fujishiro, H.

    2014-05-07

    The band-gap insulators RECoO{sub 3} (RE = Nd{sup 3+}, Sm{sup 3+}, and Dy{sup 3+}) with Co{sup 3+} ions stabilized in the non-magnetic low-spin state have been investigated by specific heat measurements. The experiments evidence an antiferromagnetic ordering of the rare earths with Néel temperature of T{sub N} = 1.25, 1.50, and 3.60 K for NdCoO{sub 3}, SmCoO{sub 3}, and DyCoO{sub 3}, respectively. With increasing external field, the lambda peak in specific heat, indicative of the transition, shifts to lower temperatures and vanishes for field of about 3 T. Starting from this point, a broader Schottky peak is formed, centered in 1 K range, and its position is moved to higher temperatures proportionally to applied field. The origin of the peak is in Zeeman splitting of the ground Kramers doublet, and the gradual shift with field defines effective g-factors for the rare-earth pseudospins in studied compounds. The results obtained are confronted with the calculations of crystal field splitting of the rare-earth multiplets.

  18. Mimicking the magnetic properties of rare earth elements using superatoms.

    PubMed

    Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W

    2015-04-21

    Rare earth elements (REs) consist of a very important group in the periodic table that is vital to many modern technologies. The mining process, however, is extremely damaging to the environment, making them low yield and very expensive. Therefore, mimicking the properties of REs in a superatom framework is especially valuable but at the same time, technically challenging and requiring advanced concepts about manipulating properties of atom/molecular complexes. Herein, by using photoelectron imaging spectroscopy, we provide original idea and direct experimental evidence that chosen boron-doped clusters could mimic the magnetic characteristics of REs. Specifically, the neutral LaB and NdB clusters are found to have similar unpaired electrons and magnetic moments as their isovalent REs (namely Nd and Eu, respectively), opening up the great possibility in accomplishing rare earth mimicry. Extension of the superatom concept into the rare earth group not only further shows the power and advance of this concept but also, will stimulate more efforts to explore new superatomic clusters to mimic the chemistry of these heavy atoms, which will be of great importance in designing novel building blocks in the application of cluster-assembled nanomaterials. Additionally, based on these experimental findings, a novel "magic boron" counting rule is proposed to estimate the numbers of unpaired electrons in diatomic LnB clusters.

  19. Raman scattering study of rare-earth hexaboride

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  20. Preparation and use of rare-earth primary standards for INAA of an NIST SRM

    SciTech Connect

    Becker, D.A.; Greenberg, R.R.

    1994-12-31

    A complete set of rare-earth primary standards was prepared for a recent certification analysis of a National Institute of Standards and Technology (NIST) standard reference material (SRM). This was for the second renewal of the {open_quotes}Trace Elements in Coal Fly Ash{close_quotes} (SRM 1633b), which was undergoing analysis for certification of major, minor, and trace elements. Unlike the two earlier versions of this SRM, this second renewal is planned to certify a number of the rare-earth elements, using instrumental neutron activation analysis (INAA) plus a second analytical technique.

  1. Rare-earth distribution behaviour and lattice parameter changes on rare-earth substituted garnet single crystals

    NASA Astrophysics Data System (ADS)

    Kimura, H.; Numazawa, T.; Sato, M.

    1994-08-01

    The selection of rare-earth substituted Ga and Al garnets in solid solution and their growth to single crystals using the conventional Czochralski technique is described. The crystals grown were investigated for their distribution behavior and lattice parameter changes in order to understand their characteristics in the solid solution. Investigation was by means of an ICP chemical analysis and X-ray diffraction analysis with powdered samples ground from wafers taken from both the tops and tails of the crystals grown.

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

    SciTech Connect

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou; Yang, Ping; Zhang, Hailu; Deng, Zongwu

    2013-11-15

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

  3. Catalysis of Ugi four component coupling reactions by rare earth metal triflates.

    PubMed

    Okandeji, Babajide O; Gordon, Jonathan R; Sello, Jason K

    2008-07-18

    Substoichiometric quantities of scandium and ytterbium triflate increase the yield of Ugi four component coupling reactions of aromatic aldehydes 2- to 7-fold. These rare earth metal triflates enhance the reaction yields primarily via activation of the imine intermediate of this multicomponent reaction.

  4. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ► The O{sup 2−}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ► The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ► There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2−}-Sm{sup 3+}, O{sup 2−}-Dy{sup 3+} and O{sup 2−}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2−}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

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

    PubMed

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

    2015-06-01

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

  6. 77 FR 58578 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same... the sale within the United States after importation of certain sintered rare earth magnets, methods of... after importation of certain sintered rare earth magnets, methods of making same and products...

  7. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section...

  8. 40 CFR 721.10550 - Rare earth salt of a carboxylic acid (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Rare earth salt of a carboxylic acid... Specific Chemical Substances § 721.10550 Rare earth salt of a carboxylic acid (generic). (a) Chemical... as rare earth salt of a carboxylic acid (PMN P-05-324) is subject to reporting under this section...

  9. The formation of crystals in glasses containing rare earth oxides

    SciTech Connect

    Fadzil, Syazwani Mohd; Hrma, Pavel; Crum, Jarrod; Siong, Khoo Kok; Ngatiman, Mohammad Fadzlee; Said, Riduan Mt

    2014-02-12

    Korean spent nuclear fuel will reach the capacity of the available temporary storage by 2016. Pyroprocessing and direct disposal seems to be an alternative way to manage and reuse spent nuclear fuel while avoiding the wet reprocessing technology. Pyroprocessing produces several wastes streams, including metals, salts, and rare earths, which must be converted into stabilized form. A suitable form for rare earth immobilization is borosilicate glass. The borosilicate glass form exhibits excellent durability, allows a high waste loading, and is easy to process. In this work, we combined the rare earths waste of composition (in wt%) 39.2Nd{sub 2}O{sub 3}–22.7CeO{sub 2}–11.7La{sub 2}O{sub 3}–10.9PrO{sub 2}–1.3Eu{sub 2}O{sub 3}–1.3Gd{sub 2}O{sub 3}–8.1Sm{sub 2}O{sub 3}–4.8Y{sub 2}O{sub 3} with a baseline glass of composition 60.2SiO{sub 2}–16.0B{sub 2}O{sub 3}–12.6Na{sub 2}O–3.8Al{sub 2}O{sub 3}–5.7CaO–1.7ZrO{sub 2}. Crystallization in waste glasses occurs as the waste loading increases. It may produce complicate glass processing and affect the product quality. To study crystal formation, we initially made glasses containing 5%, 10% and 15% of La{sub 2}O{sub 3} and then glasses with 5%, 10% and 15% of the complete rare earth mix. Samples were heat-treated for 24 hours at temperatures 800°C to 1150°C in 50°C increments. Quenched samples were analyzed using an optical microscope, scanning electron microscope with energy dispersive spectroscopy, and x-ray diffraction. Stillwellite (LaBSiO{sub 5}) and oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26}) were found in glasses containing La{sub 2}O{sub 3}, while oxyapatite (Ca{sub 2}La{sub 8}Si{sub 6}O{sub 26} and NaNd{sub 9}Si{sub 6}O{sub 26}) precipitated in glasses with additions of mixed rare earths. The liquidus temperature (T{sub L}) of the glasses containing 5%, 10% and 15% La{sub 2}O{sub 3} were 800°C, 959°C and 986°C, respectively; while T{sub L} was 825°C, 1059°C and 1267°C for glasses

  10. SEPARATION OF TRANSURANIC ELEMENTS FROM RARE EARTH COMPOUNDS

    DOEpatents

    Kohman, T.P.

    1961-11-21

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

  11. Resonance electronic Raman scattering in rare earth crystals

    SciTech Connect

    Williams, G.M.

    1988-11-10

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

  12. Magnetism in rare-earth quasicrystals: RKKY interactions and ordering

    NASA Astrophysics Data System (ADS)

    Thiem, Stefanie; Chalker, J. T.

    2015-04-01

    We study magnetism in simple models for rare-earth quasicrystals, by considering Ising spins on a quasiperiodic tiling, coupled via RKKY interactions. Computing these interactions from a tight-binding model on the tiling, we find that they are frustrated and strongly dependent on the local environment. Although such features are often associated with spin glass behaviour, we show using Monte Carlo simulations that the spin system has a phase transition to a low-temperature state with long-range quasiperiodic magnetic order.

  13. Rare earth element patterns in biotite, muscovite and tourmaline minerals

    SciTech Connect

    Laul, J.C.; Lepel, E.A.

    1986-04-21

    Rare earth element concentrations in the minerals biotite and muscovite from the mica schist country rocks of the Etta pegmatite and tourmalines from the Bob Ingersoll pegmatite have been measured by INAA and CNAA. The concentrations range from 10/sup -4/ g/g to 10/sup -10g//sub g/. The REE patterns of biotite, muscovite and tourmaline reported herein are highly fractionated from light to heavy REE. The REE concentrations in biotite and muscovite are high and indigenous. The pegmatite tourmalines contain low concentrations of REE. Variations in tourmaline REE patterns reflect the geochemical evolution of pegmatite melt/fluid system during crystallization.

  14. Small hole polarons in rare-earth titanates

    SciTech Connect

    Bjaalie, L.; Moetakef, P.; Cain, T. A.; Janotti, A.; Himmetoglu, B.; Stemmer, S.; Van de Walle, C. G.; Ouellette, D. G.; Allen, S. J.

    2015-06-08

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

  15. Raman Investigations of Rare Earth Arsenate Single Crystals

    SciTech Connect

    Barros, G; Santos, C. C.; Ayala, A. P.; Guedes, I.; Boatner, Lynn A; Loong, C. K.

    2010-01-01

    Polarized Raman Spectroscopy was used to investigate the room-temperature phonon characteristics of a series of rare-earth arsenate (REAsO4, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumber of the internal modes of the AsO4 tetrahedron increased with increasing atomic number, and for three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber.

  16. Compositional and phase relations among rare earth element minerals

    NASA Technical Reports Server (NTRS)

    Burt, D. M.

    1989-01-01

    A review is presented that mainly treats minerals in which the rare-earth elements are essential constituents, e.g., bastnaesite, monazite, xenotime, aeschynite, allanite. The chemical mechanisms and limits of REE substitution in some rock-forming minerals (zircon, apatite, titanite, garnet) are also derived. Vector representation of complex coupled substitutions in selected REE-bearing minerals is examined and some comments on REE-partitioning between minerals as related to acid-based tendencies and mineral stabilities are presented. As the same or analogous coupled substitutions involving the REE occur in a wide variety of mineral structures, they are discussed together.

  17. Recycling of rare earth particle by mini-hydrocyclones.

    PubMed

    Yu, Jian-Feng; Fu, Jian; Cheng, Hao; Cui, Zhengwei

    2017-03-01

    Mini-hydrocyclones were applied to separate the fine rare earth particles from the suspensions. The effects of the flow rate, split ratio, and feed concentration on the total separation efficiency and grade separation efficiency were studied. The combined effects of the flow rate (1200-1600L/h), split ratio (20-60%) and concentration (0.6-1.0wt%) on the total separation efficiency in mini-hydrocyclones were investigated using a response surface methodology. The optimum operating parameters for a total separation efficiency of 92.5% were: feed flow rate=1406L/h, split ratio=20%, and feed concentration=1wt%.

  18. Synthesis and luminescence of some rare earth metal complexes

    NASA Astrophysics Data System (ADS)

    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.

  19. Anomalous Hall Effect in a Feromagnetic Rare-Earth Cobalite

    NASA Technical Reports Server (NTRS)

    Samoilov, A. V.; Yeh, N. C.; Vasquez, R. P.

    1996-01-01

    Rare-Earth manganites and cobalites with the perovskite structure have been a subject of great recent interest because their electrical resistance changes significantly when a magnetic field is applied...we have studied the Hall effect in thin film La(sub 0.5)Ca(sub 0.5)CoO(sub 3) material and have obtained convincing evidence fo the so called anomalous Hall effect, typical for magnetic metals...Our results suggest that near the ferromagnetic ordering temperature, the dominant electron scattering mechanism is the spin fluctuation.

  20. Double-exchange mechanism in rare-earth compounds

    SciTech Connect

    Gulacsi, M.

    2015-03-15

    We show that double-exchange mechanism is responsible for ferromagnetism in low dimensional rare-earth compounds. We use the bosonized version of the one-dimensional Anderson lattice model in Toulouse limit to characterize the properties of the emerging ferromagnetic phase. We give a comprehensive description of the ferromagnetic ordering of the correlated electrons which appears at intermediate couplings and doping. The obtained ferromagnetic phase transitions have been identified to be an order–disorder transition of the quantum random transverse-field Ising type.

  1. Rare earth chalcogenide stoichiometry determination. [of thermoelectric properties

    NASA Technical Reports Server (NTRS)

    Lockwood, R. A.

    1983-01-01

    Rare earth chalcogenides, and particularly lanthanum sulfide, are currently explored as candidate materials for thermoelectric applications. Since the electrical properties of LaS(x) are largely determined by its stoichiometry, a simple and accurate method has been developed for determining the value of x. The procedure involves dissolving a weighted sample in acid and measuring the amount of hydrogen evolved by the lanthanum that is in excess of the 1.500 ratio of S/La. The analytical error in the determination of x in LaS(x) is about 0.001.

  2. Synthesis of nanocrystalline rare earth oxides by glycothermal method

    SciTech Connect

    Hosokawa, Saburo; Iwamoto, Shinji; Inoue, Masashi

    2008-11-03

    The reaction of yttrium acetate hydrate in 1,2-propanediol at 300 deg. C yielded a product containing acetate groups and glycol moieties. From this product, Y{sub 2}O{sub 3} was directly crystallized at 400 deg. C without the formation of a carbonate oxide phase. The thus-obtained Y{sub 2}O{sub 3} samples had a small crystallite size (2.2 nm) and significantly large surface area (280 m{sup 2}/g). Other nanocrystalline rare earth (Gd-Yb) oxides were also obtained by this method.

  3. Observation of Anomalous Phonons in Orthorhombic Rare-earth Manganites

    SciTech Connect

    P Gao; H Chen; T Tyson; Z Liu; J Bai; L Wang; Y Chio; S Cheong

    2011-12-31

    We observe the appearance of a phonon near the lock-in temperature in orthorhombic REMnO{sub 3} (RE denotes rare earth) (RE: Lu and Ho) and anomalous phonon hardening in orthorhombic LuMnO{sub 3}. The anomalous phonon occurs at the onset of spontaneous polarization. No such changes were found in incommensurate orthorhombic DyMnO{sub 3}. These observations directly reveal different electric polarization mechanisms in the E-type and incommensurate-type orthorhombic REMnO{sub 3}.

  4. Magnetoelectric and magnetoelastic properties of rare-earth ferroborates

    NASA Astrophysics Data System (ADS)

    Kadomtseva, A. M.; Popov, Yu. F.; Vorob'ev, G. P.; Pyatakov, A. P.; Krotov, S. S.; Kamilov, K. I.; Ivanov, V. Yu.; Mukhin, A. A.; Zvezdin, A. K.; Kuz'menko, A. M.; Bezmaternykh, L. N.; Gudim, I. A.; Temerov, V. L.

    2010-06-01

    The magnetic, electric, magnetoelectric, and magnetoelastic properties of rare-earth ferroborates RFe3(BO3)4 (R =Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er) as well as yttrium ferroborate YFe3(BO3)4 have been studied comprehensively. A strong dependence not only of the magnetic but also magnetoelectric properties on the type of rare-earth ion, specifically, on its anisotropy, which determines the magnetic structure and the large contribution to the electric polarization, has been found. This is manifested in the strong temperature dependence of the polarization below the Néel point TN and its specific field dependence, which is determined by the competition between the external and exchange f-d fields. A close correlation has been found between the magnetoelastic properties of ferroborates and the magnetoelastic and magnetic anomalies at magnetic-field induced phase transitions. It is found that in easy-plane ferroborates, together with magnetic-field induced electric polarization spontaneous polarization also arises below the Néel point. The ferroelectric ordering in ferroborates is of extrinsic character, giving rise to strong magnetoelectric coupling below TN. Aside from the antiferromagnetic phase transition, the particulars of the structural phase transition accompanied by anomalies of the dielectric and magnetoelectric properties are examined for the first time. The character of the dielectric anomalies at a structural transition is analyzed for the first time on the basis of Landau's approach.

  5. Sublattice Magnetic Relaxation in Rare Earth Iron Garnets

    SciTech Connect

    McCloy, John S.; Walsh, Brian

    2013-07-08

    The magnetic properties of rare earth garnets make them attractive materials for applications ranging from optical communications to magnetic refrigeration. The purpose of this research was to determine the AC magnetic properties of several rare earth garnets, in order to ascertain the contributions of various sublattices. Gd3Fe5O¬12, Gd3Ga5O12, Tb3Fe5O12, Tb3Ga5O12, and Y3Fe5O12 were synthesized by a solid state reaction of their oxides and verified by x-ray diffraction. Frequency-dependent AC susceptibility and DC magnetization were measured versus temperature (10 – 340 K). Field cooling had little effect on AC susceptibility, but large effect on DC magnetization, increasing magnetization at the lowest temperature and shifting the compensation point to lower temperatures. Data suggest that interaction of the two iron lattices results in the two frequency dependent magnetic relaxations in the iron garnets, which were fit using the Vogel-Fulcher and Arrhenius laws.

  6. Intermediate phases in some rare earth-ruthenium systems

    NASA Technical Reports Server (NTRS)

    Sharifrazi, P.; Raman, A.; Mohanty, R. C.

    1984-01-01

    The phase equilibria and crystal structures of intermediate phases were investigated in eight representative RE-Ru systems using powder X-ray diffraction and metallographic techniques. The Fe3C, Mn5C2 and Er5Ru3 structures occur in all but the Ce-Ru systems. Phases analogous to Er5Ru3 possess an unknown crystal structure similar to Er5Rh3(I). MgCu2 and MgZn2 type Laves phases are encountered in the light rare earth and heavy rare earth systems, respectively, and RERu2 phases, where RE = Nd and Sm, possess both the Laves phase structures. An intermediate phase, NdRu, with an unknown structure, occurs only in the Nd-Ru system. A bcc structure with 40 atoms per unit cell is encountered in the phases Er3Ru2 and Y3Ru2. The behavior of cerium in Ce-Ru alloys is unique in that four unidentified structures, not encountered in other RE-Ru systems, have been encountered. Also a phase designated as Ce3Ru is found with the Th7Fe3 type structure.

  7. Bacterial Cell Surface Adsorption of Rare Earth Elements

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  8. Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Zhu, Dongming

    2005-01-01

    Multicomponent, rare-earth-doped, perovskite-type thermal-barrier coating materials have been developed in an effort to obtain lower thermal conductivity, greater phase stability, and greater high-temperature capability, relative to those of the prior thermal-barrier coating material of choice, which is yttria-partially stabilized zirconia. As used here, "thermal-barrier coatings" (TBCs) denotes thin ceramic layers used to insulate air-cooled metallic components of heat engines (e.g., gas turbines) from hot gases. These layers are generally fabricated by plasma spraying or physical vapor deposition of the TBC materials onto the metal components. A TBC as deposited has some porosity, which is desirable in that it reduces the thermal conductivity below the intrinsic thermal conductivity of the fully dense form of the material. Undesirably, the thermal conductivity gradually increases because the porosity gradually decreases as a consequence of sintering during high-temperature service. Because of these and other considerations such as phase transformations, the maximum allowable service temperature for yttria-partially stabilized zirconia TBCs lies in the range of about 1,200 to 1,300 C. In contrast, the present multicomponent, rare-earth-doped, perovskite-type TBCs can withstand higher temperatures.

  9. [Infrared multiphoton quantum cutting phenomena of rare earth materials].

    PubMed

    Chen, Xiao-Bo; Yang, Guo-Jian; Zhang, Yun-Zhi; Deng, Zhi-Wei; Hu, Li-Li; Li, Song; Yu, Chun-Lei; Chen, Zhi-Jian; Cui, Jian-Sheng; Chen, Xiao-Duan; Zhou, Hong-Yu; Wu, Zheng-Long

    2012-10-01

    Infrared quantum cutting of rare earth ion is an international hot research field. It is significant for the enhancement of solar cell efficiency and for the reduction of solar cell price. The present paper summarizes the research significance of infrared quantum cutting of rare earth ion. Based on the summarization of general principle and loss mechanism of solar cell, the possible method to enhance the solar cell efficiency by infrared quantum cutting is analyzed. Meanwhile, the present paper summarizes the infrared quantum cutting phenomena of Er3+ ion single-doped material. There is intense 4I13/2 --> 4I15/2 infrared quantum cutting luminescence of Er3+ ion when the 2H11/2 energy level is excited. The intense {2H11/2 --> 4I9/2, 4I15/2 --> 4I13/2} cross energy transfer is the main reason for the result in the high quantum cutting efficiency when the 2H11/2 energy level is excited.

  10. Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

    SciTech Connect

    Jia, Li-Ping; Zhang, Qiang; Yan, Bing

    2014-07-01

    Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF{sub 5} (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba{sub 2}REF{sub 7} (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd{sup 3+}, Eu{sup 3+}, Tb{sup 3+}) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba{sub 2}LaF{sub 7}:Yb, Tm(Er), Ba{sub 2}REF{sub 7}:Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed.

  11. Rare Earth elements as sediment tracers in Mangrove ecosystems

    NASA Astrophysics Data System (ADS)

    Ramanathan, A. L.; Swathi, S.

    2013-05-01

    Rare earth elements have been widely used as geochemical source fingerprints of rocks and sediments to study processes involving cosmo-chemistry, igneous petrology, tectonic setting and for investigations of water-rock interactions and weathering processes including transport of weathering products to the oceans.Many studies have addressed the use of REEs in investigating the environmental impact of human activity and demonstrated that the REE natural distribution in sediment from densely industrialised and populated regions can be altered by anthropogenic influences.The coastal wetlands like Mangroves are ultimate sinks for all the material derived from the terrestrial and marine environment.The high productivity and low ratio of sediment respiration to net primary production gives mangrove sediments the potential for long-term sequestration of these pollutants/metals before reaching the coastal ocean. Geochemical study of REE in these sedimentary systems is useful for determining the nature of the biogeochemical processes. In particular, REE show a great sensitivity to pH changes, redox conditions and adsorption/ desorption reactions. So, they may be used as markers of discharge provenance, weathering processes, changes in environmental conditions in the water and sediments of Mangrove/wetland systems. Our study aims to establish the abundance, distribution and enrichment of REEs to track the sediment sources and biogeochemical processes occurring in the mangrove environment.Core sediments were collected from the different environmental settings within the Pichavaram mangrove area.Higher REE concentration in Pichavaram sediments indicated greater input from sources like terrestrial weathering and anthropogenic activities which in turn are affected by saline mixing and dynamic physico-chemical processes occurring in the mangrove environment. REE enrichment order was attributed to the alkaline pH (7-8.5) and reducing conditions prevailing in the mangrove

  12. Bis(imino)diphenylamido rare-earth metal dialkyl complexes: synthesis, structure, and catalytic activity in living ring-opening ε-caprolactone polymerization and copolymerization with γ-butyrolactone.

    PubMed

    Du, Gaixia; Wei, Yanling; Zhang, Wei; Dong, Yuping; Lin, Zhengguo; He, Huan; Zhang, Shaowen; Li, Xiaofang

    2013-01-28

    Bis(imino)diphenylamido rare-earth metal dialkyl complexes [o-(2,6-(i)Pr(2)-C(6)H(3)-N=C-C(6)H(4))(2)-N]Ln(CH(2)SiMe(3))(2) (1: Ln = Sc; 2: Ln = Lu; 3: Ln = Y) have been synthesized in good yields and structurally characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction studies. They serve as highly efficient single-component catalysts both for the living ring-opening ε-caprolactone polymerization and random copolymerization with γ-butyrolactone, with the activity being dependent on the steric hindrance around the metal center, yielding high molecular weight PCLs or P(CL-co-BL)s with narrow molecular weight distributions.

  13. A study on artificial rare earth (RE2O3) based neutron absorber.

    PubMed

    Kim, Kyung-O; Kim, Jong Kyung

    2015-11-01

    A new concept of a neutron absorption material (i.e., an artificial rare earth compound) was introduced for criticality control in a spent fuel storage system. In particular, spent nuclear fuels were considered as a potential source of rare earth elements because the nuclear fission of uranium produces a full range of nuclides. It was also found that an artificial rare earth compound (RE2O3) as a High-Level Waste (HLW) was naturally extracted from pyroprocessing technology developed for recovering uranium and transuranic elements (TRU) from spent fuels. In this study, various characteristics (e.g., activity, neutron absorption cross-section) were analyzed for validating the application possibility of this waste compound as a neutron absorption material. As a result, the artificial rare earth compound had a higher neutron absorption probability in the entire energy range, and it can be used for maintaining sub-criticality for more than 40 years on the basis of the neutron absorption capability of Boral™. Therefore, this approach is expected to vastly improve the efficiency of radioactive waste management by simultaneously keeping HLW and spent nuclear fuel in a restricted space.

  14. Rare Earth Elements reveal past earthquakes on limestone normal faults

    NASA Astrophysics Data System (ADS)

    Manighetti, I.; Boucher, E.; Chauvel, C.; Schlagenhauf, A.; Benedetti, L.

    2009-12-01

    In 2008, we suggested that the chemical composition of the rocks which form well preserved, seismically exhumed fault scarps might record past major earthquakes (Carcaillet et al., 2008) because those scarp surfaces consist of a vertical succession of zones that have been exposed at different times by the repeating earthquakes, thus weathered over different time spans. In this pioneer study, we validated this hypothesis using the changes in chemical compositions (major and trace elements) of 15 carbonate rock samples collected from the base to the top of the seismically exhumed, 10 m-high Magnola normal fault scarp (Abruzzes, Central Italy). However, the number of available samples was insufficient to fully assess the validity of the model. Here we present trace element data on 27 additional samples collected systematically every 25 cm along the Magnola scarp, as well as on 7 scarp samples buried below the colluvium hence representing the first 4 meters of the scarp before exhumation. The scarp rocks buried in the first meter of the ground appear significantly enriched in Rare Earth elements (REE): they contain 60% more REE than the rocks located either deeper in the ground or immediately above the ground level. This concentration peak most probably results from enrichment of the scarp rocks by interaction with the impurity-doped, acidic, upper soil. Above the ground surface and along the scarp, most element concentrations (70%) decrease up-dip, generally by more than 50%; we attribute this trend to leaching and dissolution-recrystallization of purer calcite through time. The top of the scarp having been exposed for a longer period of time, its surface lost more of the trace elements contained in the rocks. However, the upward decrease in REE contents is not linear and 4 REE concentration peaks can be recognized along the exposed scarp. The position of these 4 peaks coincide with the zones identified by Schlagenhauf et al. (2009) and Palumbo et al. (2004) as

  15. Rare earths exposure and male infertility: the injury mechanism study of rare earths on male mice and human sperm.

    PubMed

    Chen, Jun; Xiao, Heng-Jun; Qi, Tao; Chen, Di-Ling; Long, He-Ming; Liu, Song-Hao

    2015-02-01

    The weight; testis/body coefficient; levels of LDH, SDH, SODH, G-6PD, and testosterone; cell cycle; and cell apoptosis of the male mice were influenced after being treated with 200 mg/[kg/day] of rare earths suspension for 3 weeks. The "Raman fingerprints" of the human sperm DNA exposed to 0.040 mg/ml CeCl3 were very different from those of the untreated; the Raman bands at 789 cm(-1) (backbone phosphodiester), PO4 backbone at 1,094 cm(-1), methylene deformation mode at 1,221 cm(-1), methylene deformation mode at 1,485 cm(-1), and amide II at 1,612 cm(-1), of which intensities and shifts were changed, might be the diagnostic biomarkers or potential therapeutic targets. The injury mechanism might be that the rare earths influence the oxidative stress and blood testosterone barrier, tangle the big biomolecule concurrently, which might cause the testicular cells and vascular system disorder and/or dysfunction, and at the same time change the physical and chemical properties of the sperm directly.

  16. Thermochemical study of rare earth and nitrogen incorporation in glasses

    NASA Astrophysics Data System (ADS)

    Zhang, Yahong

    Rare earth containing aluminosilicate, borosilicate, aluminate and nitrogen containing aluminosilicate glasses are technically important materials. They have extraordinary physical and chemical properties such as high glass transition temperature, very low electrical conductivity, and excellent chemical stability. These unique properties lead to applications as coatings on metals and ceramics, optical fibers, semiconductors, and nuclear waste containment materials. In addition, such systems contain the most widely used additives for sintering of Si3N4, SiAlON and SiC ceramics for high temperature applications. Thermodynamic properties and the relations among energetics, structure and bonding are essential to controlling processing parameters to synthesize, at lower cost, materials having better properties. Earlier investigations mainly pertained to specific physical properties of rare-earth doped oxide and oxynitride glasses. Work on the thermodynamic stability and materials compatibility has been very sparse. High temperature solution calorimetry in molten oxide solvents is a powerful tool for the thermodynamic study of refractory materials. With implementation and improvement, this technique has been applied to the first measurement of enthalpies of formation of RE-Si-Al-O glasses, REAlO3 glasses, RE-Si-Al-O-N glasses, and Si3N 4 and Ge3N4 with high pressure spinel structure. The first successful synthesis of REAlO3 glasses has been achieved by containerless melting. Their large enthalpies of crystallization confirm that they are reluctant glass formers. For glasses along the 2REAlO3 -3SiO2 join, the strongly negative heats of mixing support the absence of miscibility gaps except possibly at very high silica content. Energetic evidence has been presented for incipient phase-ordered regions in Gd- or Hf-containing sodium alumino-borosilicate glasses for plutonium immobilization. Linear relations between enthalpies of formation of RESiAlON glasses from elements and

  17. Targeting heavy rare earth elements in carbonatite complexes

    NASA Astrophysics Data System (ADS)

    Broom-Fendley, S.; Wall, F.; Gunn, A. G.; Dowman, E.

    2012-04-01

    The world's main sources of the rare earth elements (REE) are concentrated in carbonatite complexes. These have the advantages of high grade and tonnage, combined with low thorium contents, yet they are generally enriched in light rare earths (LREE). The heavy rare earths (HREE, which include Eu-Lu and Y) are more highly sought after because of their role in new and green technologies. HREE are predominantly extracted from ion-adsorption clays in China. These are small, low grade deposits, which are often illegally mined by artisans. Increased government control, environmental legislation and local demand for REE in China have led to high prices and global concerns about the security of supply of the HREE. Alternative sources of the HREE are poorly documented. We present a review of such targets, including: (1) 'abnormal' carbonatites; (2) areas around LREE-rich complexes such as breccia, fenite and latter stage veins; and (3) weathered carbonatites. At Lofdal, Namibia, carbonatite dykes contain xenotime-(Y) together with LREE minerals. The original chemistry of the carbonatite magma, coupled with late-stage magma and fluid evolution, seem to be controlling factors [1, 2]. The Khibina carbonatite, Kola Peninsula, Russia, is an example of where early LREE carbonatites become increasing HREE-enriched as magmas evolve to carbo-hydrothermal fluids [3]. Around carbonatite complexes in Malawi HREE enrichment can be found in breccia and in fenite. Breccia around Songwe shows areas with high Y/La ratios within the matrix caused by narrow zones of xenotime enrichment. Fenite around Kangankunde and Chilwa Island has higher HREE:LREE ratios than the carbonatite [4]. At weathered complexes, such as at Mount Weld in Western Australia, changes in both HREE concentration and LREE:HREE ratios are observed. In currently unworked sections of the deposit, the HREE mineral churchite (YPO4.H2O) has formed concentrations due to groundwater flow [5]. These areas of enrichment are

  18. The Marine Geochemistry of the Rare Earth Elements

    DTIC Science & Technology

    1983-09-01

    C3): 2045-2056. BACON, M.P., P.G. BREWER, D.W. SPENCER, T.W. MURRAY & T. GODDARD (1980). Lead - 210 , polonium - 210 , manganese and iron in the Cariaco...191 La and Pr 197 Ce: its oxidation and reduction 197 Eu 207 4.5. Conclusions 210 CHAPTER 5. Behaviour of the Rare Earth Elements in anoxic waters of...0.142 140Ce(n, )14ICe 0.58 0.48 2.89 0.0053 41Pr(n,e.)142Pr 11.5 14.1 57.4 0.17 l46Nd(n,a-)l47Nd 1.4 3.2 6.98 0.0039 152Sni(n,a)153Sm 210 2530 1047

  19. Orthodontic rare earth magnets--in vitro assessment of cytotoxicity.

    PubMed

    Bondemark, L; Kurol, J; Wennberg, A

    1994-11-01

    The aim of this study was to assess and compare in vitro the cytotoxic effects of uncoated and parylene-coated rare earth magnets, used in orthodontics. Cytotoxicity of samarium-cobalt magnets (SmCo5 and Sm2Co17) and neodymium-iron-boron magnets (Nd2Fe14B) was assessed by two in vitro methods, the millipore filter method and an extraction method. Orthodontic stainless steel brackets served as controls. Uncoated SmCo5-magnets showed high cytotoxicity while uncoated Sm2Co17-magnets demonstrated moderate cytotoxicity. Uncoated neodymium-iron-boron magnets, as well as parylene coated Sm2Co17-magnets and parylene-coated neodymium-iron-boron magnets, showed negligible cytotoxicity. Short-term exposure to a static magnetic field did not cause any cytotoxic effect on the cells.

  20. Rare-Earth Metal Postmetallocene Catalysts with Chelating Amido Ligands

    NASA Astrophysics Data System (ADS)

    Li, Tianshu; Jenter, Jelena; Roesky, Peter W.

    This review deals with the synthesis and the catalytic application of noncyclopentadienyl complexes of the rare-earth elements. The main topics of the review are amido metal complexes with chelating bidentate ligands, which show the most similarities to cyclopentadienyl ligands. Benzamidinates and guanidinates will be reviewed in a separate contribution within this book. Beside the synthesis of the complexes, the broad potential of these compounds in homogeneous catalysis is demonstrated. Most of the reviewed catalytic transformations are either C-C multiple bond transformation such as the hydroamination and hydrosilylation or polymerization reaction of polar and nonpolar monomers. In this area, butadiene and isoprene, ethylene, as well as lactides and lactones were mostly used as monomers.

  1. Exposure, metabolism, and toxicity of rare earths and related compounds.

    PubMed Central

    Hirano, S; Suzuki, K T

    1996-01-01

    For the past three decades, most attention in heavy metal toxicology has been paid to cadmium, mercury, lead, chromium, nickel, vanadium, and tin because these metals widely polluted the environment. However, with the development of new materials in the last decade, the need for toxicological studies on those new materials has been increasing. A group of rare earths (RE) is a good example. Although some RE have been used for superconductors, plastic magnets, and ceramics, few toxicological data are available compared to other heavy metals described above. Because chemical properties of RE are very similar, it is plausible that their binding affinities to biomolecules, metabolism, and toxicity in the living system are also very similar. In this report, we present an overview of the metabolism and health hazards of RE and related compounds, including our recent studies. Images Figure 1. A Figure 1. B Figure 1. C PMID:8722113

  2. Vanadium oxide bronzes containing rare-earth elements

    SciTech Connect

    Volkov, V.L.; Zubkov, V.G.; Fedyukov, A.S.; Zainulin, Yu.G.

    1988-05-01

    We attempted to make phases having the general formula Ln/sub x/V/sub 2/O/sub 5/ (Ln = La, Eu, Yb) without success; the specimens usually consisted of three phases: the rare-earth orthovanadate LnVO/sub 4/, vanadium(V) oxide, and VO/sub 2/. To shift the process to give Ln/sub x/V/sub 2/O/sub 5/, heat treatment was applied to mixtures of the initial high-purity substances. The x-ray patterns were recorded with a DRON-UM1 apparatus with Cr K..cap alpha.. radiation and were processed by the Poroshok program. The IR spectra were recorded with UR-20 spectrometer with oil mulls.

  3. Rare earth elements in parasol mushroom Macrolepiota procera.

    PubMed

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

    2017-04-15

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

  4. Sonochemical synthesis of mesoporous transition metal and rare earth oxides.

    PubMed

    Wang, Yanqin; Yin, Lunxiang; Gedanken, Arahon

    2002-11-01

    Straight-extended layered mesostructures based on transItion metal (Fe, Cr) and rare earth (Y, Ce, La, Sm, Er) oxides are synthesized by sonication for 3 h. After a longer period of sonication (6 h), hexagonal mesostructures based on Y- and Er-oxides are obtained. The surface areas of the Y-based hexagonal mesophases before and after extraction are 46.5, 256 m2/g, respectively. For Er-based hexagonal mesophases, the surface areas before and after extraction are 157 and 225 m2/g. The pore sizes after extraction are 5.0 and 2.2 nm for Y- and Er-based mesophases, respectively. Hexagonal mesostructures are also obtained for Zr-based material after sonication for 3 h and the hexagonal structure is still maintained after calcinations at 400 degrees C for 4 h, although the surface area is only 35 m2/g.

  5. Gaps and pseudogaps in perovskite rare earth nickelates

    SciTech Connect

    Allen, S. James; Ouellette, Daniel G.; Kally, James; Kozhanov, Alex; Hauser, Adam J.; Mikheev, Evgeny; Zhang, Jack Y.; Moreno, Nelson E.; Son, Junwoo; Stemmer, Susanne; Balents, Leon

    2015-06-01

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

  6. Rare-earth phosphors for remote thermographic applications

    SciTech Connect

    Allison, S.W. ); Franks, L.A.; Borella, H.M.; Lutz, S.S.; Turley, W.D. ); Noel, B.W.; Beasley, A. )

    1989-04-01

    Numerous phosphors with rare-earth dopants have emissions that are strongly dependent on temperature and are therefore useful for remote-temperature measurement, especially in moving, confined, or hazardous systems. The emission properties of various phosphors of this type were measured from room temperature to {approximately}1,200{degree}C, along with data relative to their stability under thermal cycling. For practical temperature monitoring applications, thermographic phosphors must remain relatively stable under the conditions they must experience during the measurement. One important consideration then, is any change in fluorescent properties that might accompany temperature cycling. The phosphors that had the most stable behavior under cycling were La{sub 2}O{sub 2}S:Eu, YVO{sub 4}:Eu, Y{sub 2}O{sub 3}:Eu, and YVO{sub 4}:Dy. 7 refs., 11 figs., 1 tab.

  7. Standard reference water samples for rare earth element determinations

    USGS Publications Warehouse

    Verplanck, P.L.; Antweiler, R.C.; Nordstrom, D.K.; Taylor, H.E.

    2001-01-01

    Standard reference water samples (SRWS) were collected from two mine sites, one near Ophir, CO, USA and the other near Redding, CA, USA. The samples were filtered, preserved, and analyzed for rare earth element (REE) concentrations (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) by inductively coupled plasma-mass spectrometry (ICP-MS). These two samples were acid mine waters with elevated concentrations of REEs (0.45-161 ??g/1). Seventeen international laboratories participated in a 'round-robin' chemical analysis program, which made it possible to evaluate the data by robust statistical procedures that are insensitive to outliers. The resulting most probable values are reported. Ten to 15 of the participants also reported values for Ba, Y, and Sc. Field parameters, major ion, and other trace element concentrations, not subject to statistical evaluation, are provided.

  8. Actinides and Rare Earths Topical Conference (Code AC)

    SciTech Connect

    Tobin, J G

    2009-11-24

    Actinide and the Rare Earth materials exhibit many unique and diverse physical, chemical and magnetic properties, in large part because of the complexity of their f electronic structure. This Topical Conference will focus upon the chemistry, physics and materials science in Lanthanide and Actinide materials, driven by 4f and 5f electronic structure. Particular emphasis will be placed upon 4f/5f magnetic structure, surface science and thin film properties. For the actinides, fundamental actinide science and its role in resolving technical challenges posed by actinide materials will be stressed. Both basic and applied experimental approaches, including synchrotron-radiation-based investigations, as well as theoretical modeling and computational simulations, are planned to be part of the Topical Conference. Of particular importance are the issues related to the potential renaissance in Nuclear Fuels, including synthesis, oxidation, corrosion, intermixing, stability in extreme environments, prediction of properties via benchmarked simulations, separation science, environmental impact and disposal of waste products.

  9. Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Good, Brian S.

    1994-01-01

    In this paper we present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I(sub 15/2)-(4)I(sub 13/2) at 1.5 microns, and Ho, (5)I(sub 7)-(5)I(sub 8) at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

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

    PubMed

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

    2015-12-30

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

  11. Uncovering the global life cycles of the rare earth elements.

    PubMed

    Du, Xiaoyue; Graedel, T E

    2011-01-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supplies vulnerable to short and long-term disruption. To provide an improved perspective we derived the first quantitative life cycles (for the year 2007) for ten REE: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), and yttrium (Y). Of these REE, Ce and Nd in-use stocks are highest; the in-use stocks of most REE show significant accumulation in modern society. Industrial scrap recycling occurs only from magnet manufacture. We believe there is no post-customer recycling of any of these elements.

  12. Uncovering the Global Life Cycles of the Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Du, Xiaoyue; Graedel, T. E.

    2011-11-01

    The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports render primary supplies vulnerable to short and long-term disruption. To provide an improved perspective we derived the first quantitative life cycles (for the year 2007) for ten REE: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), and yttrium (Y). Of these REE, Ce and Nd in-use stocks are highest; the in-use stocks of most REE show significant accumulation in modern society. Industrial scrap recycling occurs only from magnet manufacture. We believe there is no post-customer recycling of any of these elements.

  13. 40 CFR 721.10423 - Complex strontium aluminate, rare earth doped (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Complex strontium aluminate, rare... New Uses for Specific Chemical Substances § 721.10423 Complex strontium aluminate, rare earth doped... substances identified generically as complex strontium aluminate, rare earth doped (PMNs P-12-22, P-12-23,...

  14. Pressure-induced exotic states in rare earth hexaborides

    NASA Astrophysics Data System (ADS)

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  15. Pressure-induced exotic states in rare earth hexaborides.

    PubMed

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  16. Fluorescence line-narrowing studies of rare earths in disordered solids

    SciTech Connect

    Hall, D.W.

    1982-08-10

    This dissertation is made up of two experimental studies dealing with apparently diverse topics within the subject of rare earths (RE) in solids. The first study, described in Part II, concerns the vibrations of a disordered host material about an optically active rare-earth ion as manifested by vibrationally-assisted-electronic, or vibronic transitions. Part III of the dissertation describes an investigation of the influence of site anisotropy on the purely electronic, laser transition of Nd/sup 3 +/ in glass. These two studies are bound together by the common experimental technique of laser-induced fluorescence line narrowing (FLN). By exciting fluorescence with monochromatic light of well-characterized polarization, one may select and observe the response of a single subset of the optically active ions and obtain information that is usually masked by the inhomogeneous nature of disordered solids.

  17. Rare Earth elements in individual minerals in Shergottites

    NASA Technical Reports Server (NTRS)

    Wadhwa, Meenakshi; Crozaz, Ghislaine

    1993-01-01

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

  18. Heat capacities, order-disorder transitions, and thermodynamic properties of rare-earth orthoferrites and rare-earth iron garnets

    SciTech Connect

    Parida, S.C. Rakshit, S.K.; Singh, Ziley

    2008-01-15

    Rare-earth orthoferrites, RFeO{sub 3}, and rare-earth iron garnets (RIGs) R{sub 3}Fe{sub 5}O{sub 12} (R=rare-earth elements) were prepared by citrate-nitrate gel combustion method and characterized by X-ray diffraction method. Isobaric molar heat capacities of these oxides were determined by using differential scanning calorimetry from 130 to 860 K. Order-disorder transition temperatures were determined from the heat capacity measurements. The Neel temperatures (T{sub N}) due to antiferromagentic to paramagnetic transitions in orthoferrites and the Curie temperatures (T{sub C}) due to ferrimagnetic to paramagnetic transitions in garnets were determined from the heat capacity data. Both T{sub N} and T{sub C} systematically decrease with increasing atomic number of R across the series. Lattice, electronic and magnetic contributions to the total heat capacity were calculated. Debye temperatures as a function of absolute temperature were calculated for these compounds. Thermodynamic functions like C{sub p,m}{sup o}, S{sub m}{sup o}, H{sup o}, G{sup o}, (H{sub T}{sup o}-H{sub 0}{sup o}), (H{sub T}{sup o}-H{sub 298.15K}{sup o}), -(G{sub T}{sup o}-H{sub 298.15K}{sup o})/T, {delta}{sub f}H{sub m}{sup o}, and {delta}{sub f}G{sub m}{sup o} have been generated for the compounds RFeO{sub 3}(s) and R{sub 3}Fe{sub 5}O{sub 12}(s) based on the experimental data obtained in this study and the available data in the literature. - Graphical abstract: Plot of molar heat capacities (C{sub p,m}{sup o}) of R{sub 3}Fe{sub 5}O{sub 12}(s) (R=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) against temperature (T). The inset shows the magnified portion of the heat capacity plot near the transition region indicating nearly same values of Curie temperatures for different R{sub 3}Fe{sub 5}O{sub 12}(s)

  19. Evidence for an active rare biosphere within freshwater protists community.

    PubMed

    Debroas, Didier; Hugoni, Mylène; Domaizon, Isabelle

    2015-03-01

    Studies on the active rare biosphere at the RNA level are mainly focused on Bacteria and Archaea and fail to include the protists, which are involved in the main biogeochemical cycles of the earth. In this study, the richness, composition and activity of the rare protistan biosphere were determined from a temporal survey of two lakes by pyrosequencing. In these ecosystems, the always rare OTUs represented 77.2% of the total OTUs and 76.6% of the phylogenetic diversity. From the various phylogenetic indices computed, the phylogenetic units (PUs) constituted exclusively by always rare OTUs were discriminated from the other PUs. Therefore, the rare biosphere included mainly taxa that are distant from the reference databases compared to the dominant ones. In addition, the rarest OTUs represented 59.8% of the active biosphere depicted by rRNA and the activity (rRNA:rDNA ratio) increased with the rarity. The high rRNA:rDNA ratio determined in the rare fraction highlights that some protists were active at low abundances and contribute to ecosystem functioning. Interestingly, the always rare and active OTUs were characterized by seasonal changes in relation with the main environmental parameters measured. In conclusion, the rare eukaryotes represent an active, dynamic and overlooked fraction in the lacustrine ecosystems.

  20. Determination of rare-earth elements in Luna 16 regolith sample by chemical spectral method

    NASA Technical Reports Server (NTRS)

    Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.

    1974-01-01

    An analysis was made of regolith from layer A of the Luna 16 sample for rare earth elements, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 elements and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.

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

    PubMed

    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.

  2. Application of far infrared rare earth mineral composite materials to liquefied petroleum gas.

    PubMed

    Zhu, Dongbin; Liang, Jinsheng; Ding, Yan; Xu, Anping

    2010-03-01

    Far infrared rare earth mineral composite materials were prepared by the coprecipitation method using tourmaline, cerium acetate, and lanthanum acetate as raw materials. The results of Fourier transform infrared spectroscopy show that tourmaline modified with the rare earths La and Ce has a better far infrared emitting performance. Through XRD analysis, we attribute the improved far infrared emission properties of the tourmaline to the unit cell shrinkage of the tourmaline arising from La enhancing the redox properties of nano-CeO2. The effect of the composite materials on the combustion of liquefied petroleum gas (LPG) was studied by the flue gas analysis and water boiling test. Based on the results, it was found that the composite materials could accelerate the combustion of LPG, and that the higher the emissivity of the rare earth mineral composite materials, the better the effects on combustion of LPG. In all activation styles, both air and LPG to be activated has a best effect, indicating the activations having a cumulative effect.

  3. Microemulsion synthesis, characterization of highly visible light responsive rare earth-doped Bi2O3.

    PubMed

    Wu, Shuxing; Fang, Jianzhang; Xu, Xiaoxin; Liu, Zhang; Zhu, Ximiao; Xu, Weicheng

    2012-01-01

    In this paper, Bi(2)O(3) and rare earth (La, Ce)-doped Bi(2)O(3) visible-light-driven photocatalysts were prepared in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The resulting materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, photoluminescence spectra (PLS) and UV-Vis diffuse reflectance spectroscopy. The XRD patterns of the as-prepared catalysts calcined at 500 °C exhibited only the characteristic peaks of monoclinic α-Bi(2)O(3). PLS analysis implied that the separation efficiency for electron-hole has been enhanced when Bi(2)O(3) was doped with rare earth. UV-Vis diffuse reflectance spectroscopy measurements presented an extension of light absorption into the visible region. The photocatalytic activity of the samples was evaluated by degradation of methyl orange (MO) and 2,4-dichlorophenol (2,4-DCP). The results displayed that the photocatalytic activity of rare earth-doped Bi(2)O(3) was higher than that of dopant-free Bi(2)O(3). The optimal dopant amount of La or Ce was 1.0 mol%. And the mechanisms of influence on the photocatalytic activity of the catalysts were discussed.

  4. Minerals yearbook, 1993: Rare earths, the lanthanides, yttrium, and scandium. Annual report

    SciTech Connect

    Hedrick, J.B.

    1995-03-01

    Domestic mine production of rare earths decreased in 1993. The domestic economy continued to recover slowly during the year and inflation rose a modest 2.5%. Estimated domestic apparent consumption decreased 21%; however, earnings by the major domestic processor reportedly increased amid a slight decline in sales. Demand increased for rare earths used in petroleum fluid cracking catalysts, automotive catalytic converters, permanent magnets, and television and lighting phosphors. Demand decreased for rare earths in automotive UV glass applications.

  5. Rare Earth Elements in National Defense: Background, Oversight Issues, and Options for Congress

    DTIC Science & Technology

    2013-09-17

    majority producer of the world’s two strongest magnets, samarium cobalt (SmCo) and neodymium iron boron (NeFeB) permanent, rare earth magnets. In the...established in Section 843.”16 They are dysprosium, erbium, europium, gadolinium, neodymium , praseodymium, and yttrium. DOD’s assessment of the forecast...retrieving them are challenging. Rare earths are divided into two groups: light rare earths (lanthanum, cerium, praseodymium, neodymium , promethium, and

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

    PubMed

    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.

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

    SciTech Connect

    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.

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

    USGS Publications Warehouse

    Hedrick, J.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 of 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.

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

    USGS Publications Warehouse

    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.

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

    PubMed

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

    2014-01-07

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

  11. [Determination of trace rare earth in fossil of dinosaurian egg by laser thermal lens spectrometry].

    PubMed

    Yan, H; Zheng, Y; Yan, S

    1997-10-01

    Determination of trace rare earth in fossil of dinosaurian egg by LTLS (Laser thermal lens spectrometry) is presented in this paper. The trace rare earth in fossil of dinosaurian egg was separated and concentrated with ion exchange method. The measure conditions and effect factors are discussedian. The LTLS was applied to the determination of trace rare earth in fossil of dinosaurian egg with satisfactory results. It provides the reference data for the studies on the fossil of dinosaurian egg and an analytical method for the determination of rare earth in geochemical sample.

  12. 2nd International Symposium on Fundamental Aspects of Rare-earth Elements Mining and Separation and Modern Materials Engineering (REES-2015)

    NASA Astrophysics Data System (ADS)

    Tavadyan, Levon, Prof; Sachkov, Viktor, Prof; Godymchuk, Anna, Dr.; Bogdan, Anna

    2016-01-01

    The 2nd International Symposium «Fundamental Aspects of Rare-earth Elements Mining and Separation and Modern Materials Engineering» (REES2015) was jointly organized by Tomsk State University (Russia), National Academy of Science (Armenia), Shenyang Polytechnic University (China), Moscow Institute of Physics and Engineering (Russia), Siberian Physical-technical Institute (Russia), and Tomsk Polytechnic University (Russia) in September, 7-15, 2015, Belokuriha, Russia. The Symposium provided a high quality of presentations and gathered engineers, scientists, academicians, and young researchers working in the field of rare and rare earth elements mining, modification, separation, elaboration and application, in order to facilitate aggregation and sharing interests and results for a better collaboration and activity visibility. The goal of the REES2015 was to bring researchers and practitioners together to share the latest knowledge on rare and rare earth elements technologies. The Symposium was aimed at presenting new trends in rare and rare earth elements mining, research and separation and recent achievements in advanced materials elaboration and developments for different purposes, as well as strengthening the already existing contacts between manufactures, highly-qualified specialists and young scientists. The topics of the REES2015 were: (1) Problems of extraction and separation of rare and rare earth elements; (2) Methods and approaches to the separation and isolation of rare and rare earth elements with ultra-high purity; (3) Industrial technologies of production and separation of rare and rare earth elements; (4) Economic aspects in technology of rare and rare earth elements; and (5) Rare and rare earth based materials (application in metallurgy, catalysis, medicine, optoelectronics, etc.). We want to thank the Organizing Committee, the Universities and Sponsors supporting the Symposium, and everyone who contributed to the organization of the event and to

  13. Combinatorial investigation of rare-earth free permanent magnets

    NASA Astrophysics Data System (ADS)

    Fackler, Sean Wu

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

  14. Energetics of Rare Earth Doped Uranium Oxide Solid Solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Lei

    The physical and chemical properties of UO2 nuclear fuels are affected as fission products accumulate during irradiation. The lanthanides, a main group of fission products, form extensive solid solutions with uranium oxide in the fluorite structure. Thermodynamic studies of such solid solutions had been performed to obtain partial molar free energies of oxygen as a function of dopant concentration and temperature; however, direct measurement of formation enthalpies was hampered by the refractory nature of these oxides. In this work, high temperature oxide melt solution calorimetry was utilized to study the thermochemistry of various rare earth doped uranium oxide LnxU 1-xO2-0.5x+y (Ln = La, Y, Nd) over a wide range of dopant concentrations and oxygen contents. The sintered solid solutions were carefully characterized to determine their phase purity, chemical composition, and uranium oxidation state, with most of the materials in the oxygen excess regime. The enthalpies of formation of LnxU1-xO2-0.5x+y were calculated from the calorimetric data. The oxidation enthalpies of these solid solutions are similar to that of UO2. The formation enthalpies from constituent oxides (LnO1.5, UO2, and UO3) become increasingly negative with addition of dopant cations and appear relatively independent of the uranium oxidation state (oxygen content) when the type and concentration of the dopants are the same. This is valid in the oxygen excess regime; thus an estimation of formation enthalpies of LnxU1-xO2 materials can be made. The formation enthalpies from elements of hyperstoichiometric LnxU1-xO 2-0.5x+y materials obtained from calorimetric measurements are in good agreement with those calculated from free energy data. A direct comparison between the formation enthalpies from calorimetric study and computational research using density functional theory was also performed. The experimental and computational energies of LnxU 1-xO2 (Ln = La, Y, Nd) generally agree within 10 k

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

    NASA Astrophysics Data System (ADS)

    Chemin, Marie-Charlotte

    2015-04-01

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

  16. Rare earth modified silica-aluminas as supports for bifunctional catalysis

    SciTech Connect

    Soled, S.L.; McVicker, G.; Miseo, S.

    1996-12-31

    We have explored rare earth oxide-modified amorphous silica-aluminas as {open_quotes}permanent{close_quotes} intermediate strength acids used as supports for bifunctional catalysts. The addition of well dispersed weakly basic rare earth oxides {open_quotes}titrates{close_quotes} the stronger acid sites of amorphous silica-alumina and lowers the acid strength to the level shown by halided aluminas. Physical and chemical probes, as well as model olefin and paraffin isomerization reactions show that acid strength can be adjusted close to that of chlorided and fluorided aluminas. Metal activity is inhibited relative to halided alumina catalysts, which limits the direct metal-catalyzed dehydrocyclization reactions during paraffin reforming but does not interfere with hydroisomerization reactions.

  17. Rare earth-doped nanocrystalline MgF2: Synthesis, luminescence and thermoluminescence

    NASA Astrophysics Data System (ADS)

    Jacobsohn, L. G.; Roy, A. L.; McPherson, C. L.; Kucera, C. J.; Oliveira, L. C.; Yukihara, E. G.; Ballato, J.

    2013-10-01

    The radioluminescence (RL) and thermoluminescence (TL) activation of MgF2 through the incorporation of rare earths is investigated in this work. These materials were obtained by ligand-free solution precipitation and calcination at 500 °C in air, and Ce, Eu and Tb were incorporated at the 1 mol% level. RL results of doped and undoped materials seem to indicate that the incorporation of rare earths creates effective luminescence centers, which is accompanied by an increase in the TL signal intensity in comparison with the undoped material. In particular, RL emission of MgF2:Ce is reported to be centered at 325 nm. The traps associated with the TL signal were found to be unstable under exposure to room light, suggesting potential for applications involving optically stimulated luminescence.

  18. Effect of rare earth metal on the spin-orbit torque in magnetic heterostructures

    NASA Astrophysics Data System (ADS)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D.

    2016-06-01

    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.

  19. Enhanced near-infrared photoacoustic imaging of silica-coated rare-earth doped nanoparticles.

    PubMed

    Sheng, Yang; Liao, Lun-De; Bandla, Aishwarya; Liu, Yu-Hang; Yuan, Jun; Thakor, Nitish; Tan, Mei Chee

    2017-01-01

    Near-infrared photoacoustic (PA) imaging is an emerging diagnostic technology that utilizes the tissue transparent window to achieve improved contrast and spatial resolution for deep tissue imaging. In this study, we investigated the enhancement effect of the SiO2 shell on the PA property of our core/shell rare-earth nanoparticles (REs) consisting of an active rare-earth doped core of NaYF4:Yb,Er (REDNPs) and an undoped NaYF4 shell. We observed that the PA signal amplitude increased with SiO2 shell thickness. Although the SiO2 shell caused an observed decrease in the integrated fluorescence intensity due to the dilution effect, fluorescence quenching of the rare earth emitting ions within the REDNPs cores was successfully prevented by the undoped NaYF4 shell. Therefore, our multilayer structure consisting of an active core with successive functional layers was demonstrated to be an effective design for dual-modal fluorescence and PA imaging probes with improved PA property. The result from this work addresses a critical need for the development of dual-modal contrast agent that advances deep tissue imaging with high resolution and signal-to-noise ratio.

  20. Rare earth elements as a fingerprint of soil components solubilization

    NASA Astrophysics Data System (ADS)

    Davranche, M.; Grybos, M.; Gruau, G.; Pédrot, M.; Dia, A.

    2009-04-01

    The retention of rare earth element (REE) in the soil profile are mainly controlled by three factors, (i) the stability of the primary REE-carrying minerals, (ii) the presence of secondary phases as clays and Fe- and Mn-oxyhydroxides and (ii) the concentration of colloidal organic matter (OM). Considering that each soil phases (mineral or organic) displays (ii) various surface properties, such as specific area, surface sites density and nature and (ii) their own REE distribution inherited from the rock weathering, their mobilization through various chemical reactions (dissolution, colloidal release….) may involve the development of various shaped REE patterns in the soil solutions. REE fractionation from the different soil phases may therefore be used to identify the response of the soil system to a particular chemical process such as reductive and/or acidic dissolution. To test this purpose, an organic-rich wetland soil sample was incubated under anaerobic condition at both pH 5 and uncontrolled pH. The REE patterns developed in the soil solution were then compared to the REE patterns obtained through either aerobic at pH 3 and 7 incubations or a chemical reduction experiment (using hydroxylamine). REE patterns in anaerobic and aerobic at pH 7 experiments exhibited the same middle rare earth element (MREE) downward concavity significant of the complexation of REE with soil OM. By contrast, under acidic condition, the REE pattern exhibited a positive Eu anomaly due to the dissolution of soil feldspar. Finally, REE pattern obtained from the chemical reducing experiment showed an intermediary flat shape corresponding to a mixing between the soil organic and mineral phases dissolution. The comparison of the various REE pattern shapes allowed to conclude that (i) biological reduction of wetland soil involved amorphous Fe(III) colloids linked to OM and, (ii) that the REE mobility was controlled by the dynamic of OM in wetland soil. They also evidence the potential of

  1. Behavior of Rare Earth Elements in Fractured Aquifers

    NASA Astrophysics Data System (ADS)

    Lee, S.; Kim, Y.; Lee, K.

    2003-12-01

    An understanding of the geochemistry of potential host rocks is very important in the site evaluation for construction of an underground geologic repository for radioactive waste. Because of similar valence and ionic radii and high similarity in electronic structure with trivalent actinides (such as Am3+ and Cm3+), the rare earth elements (REEs) have been used to predict the behavior of actinide-series elements in solution. For Am and Cm, which occur only in the trivalent states in most waste-disposal repository environments, the analogy with the REEs is particularly relevant. Krauskopf calculated the retardation factors for radionuclides in various rock materials based on some compiled data. But, in general, because the transuranic actinides do not occur naturally in appreciable quantities, their behaviors in repository environments cannot be predicted from evidence of their movement in geologic environments (mainly in groundwater) over geologic timespans. Predictions about long-term future behavior of transuranic actinides have therefore been made by extrapolation from short-term observations of their chemical properties in laboratory experiments or in field tests, but such extrapolation is fraught with uncertainty. In order to verify the behavior of Eu in various geological environments, we estimated the abundance of rare earth elements in three gneiss bodies originated from different geological environments and volcanic tuff. We also carried out some leaching experiment of fracture-filling calcite precipitated due to changes of geochemical environment in paleo-groundwater. Of the three gneisses, two gneisses are granitic-granodioritic origin and the other is tonaltic-trondjemitic origin. As a result, we could observe that Eu had a close relationship with fracture-filling calcite precipitation due to water-rock interaction. Our results show that Eu is the most variable element of REEs for the hydrogeological environment such as change of oxidation-reduction and

  2. Rare earth elements in scleractinian cold-water corals

    NASA Astrophysics Data System (ADS)

    Raddatz, J.; Liebetrau, V.; Hathorne, E. C.; Rüggeberg, A.; Dullo, W.; Frank, M.

    2012-12-01

    The Rare Earth Elements (REE) have a great potential to trace continental input, particle scavenging and the oxidation state of seawater. These REE are recorded in the skeleton of the cosmopolitan cold-water corals Lophelia pertusa. Here we use an online preconcentration ICP-MS method (Hathorne et al. 2012) to measure REE concentrations in seawater and associated cold-water coral carbonates in order to investigate their seawater origin. Scleractinian cold-water corals were collected in-situ and alive and with corresponding seawater samples covering from the European Continental Margin. The seawater REE patterns are characterized by the typical negative cerium anomaly of seawater, but are distinct for the northern Norwegian Margin and the Oslo Fjord, probably related to continental input. Initial results for the corresponding coral samples suggest that these distinct REE patterns of ambient seawater are recorded by the coral skeletons although some fractionation during incorporation into the aragonite occurs. This indicates that scleractinian cold-water corals can serve as a valuable archive for seawater derived REE signatures, as well radiogenic Nd isotope compositions. In a second step we analysed fossil coral samples from various locations, which were oxidatively and reductively cleaned prior to analysis. Initial results reveal that sediment-buried fossil (early Pleistocene to Holocene) coral samples from the Norwegian Margin and the Porcupine Seabight (Challenger Mound, IODP Site 1317) do not show the expected seawater REE patterns. In particular, the fossil coral-derived REE patterns lack a negative cerium anomaly suggesting that fossil coral-REE patterns do not represent ambient seawater. Thus, we suggest that the oxidative-reductive cleaning method widely used for cleaning of marine carbonates such as foraminifera prior to measurements of seawater-derived trace metal and isotope compositions are not sufficient for REE and Nd isotopes in sediment-buried coral

  3. Diagenetic uptake of rare earth elements by conodont apatite

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The rare earth element (REE) composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction, based on the assumption of preservation of a hydrogenous (seawater-derived) REE signal. Recent work, however, has begun to question the provenance of REEs in conodonts, emphasizing the importance of REEs released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment. Here, we investigate patterns of REE and trace-element abundance in conodonts and their host sediments from the Early to Late Ordovician Huanghuachang and Chenjiahe sections of Hubei Province, South China. Several lines of evidence indicate that REEs in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis: (1) REEs in conodonts show a strong positive correlation to Th and other lithogenic elements; (2) conodonts and whole-rock samples show general patterns of REE and trace-element enrichment that are highly similar to each other and bear no resemblance to seawater elemental concentrations; (3) similar patterns are observed in Triassic conodonts and whole-rock samples; and (4) Y/Ho ratios in conodonts are mostly <40 (mean ~33), values that are consistent with derivation of >90% of REEs from lithogenous sources. Conodonts show pronounced middle rare earth element (MREE) enrichment, a pattern that is unambiguously of diagenetic origin owing to its association with lower Y/Ho ratios. With increasing MREE enrichment of conodont samples, U concentrations and LaN/YbN ratios shift from high to low, and Mn concentrations from low to high. These patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions (i.e., in the zone of Mn(IV) and Fe(III) reduction) but continued at greater burial depths, with most acquisition of secondary REEs at later diagenetic stages. Our findings indicate that (1

  4. Synthesis, characterization, antioxidant activity and DNA-binding studies of three rare earth (III) complexes with 1-(4-aminoantipyrine)-3-tosylurea ligand.

    PubMed

    Xi, Pin-xian; Xu, Zhi-hong; Liu, Xiao-hui; Chen, Feng-juan; Zeng, Zheng-zhi; Zhang, Xiao-wen; Liu, Ying

    2009-01-01

    1-(4-aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M=Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties of the three complexes have been investigated by UV-vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant activity and be better than standard antioxidants like vitamin C and mannitol.

  5. Characterization and Recovery of Rare Earths from Coal and By-Products

    SciTech Connect

    Granite, Evan J.; Roth, Elliot; Alvin, Mary Anne

    2016-03-25

    Coal is a precious resource, both in the United States and around the world. The United States has a 250-year supply of coal, and generates between 30 - 40% of its electricity through coal combustion. Approximately 1 Gt of coal has been mined annually in the US, although the 2015 total will likely be closer to 900 Mt (http://www.eia.gov/coal/production/quarterly/). Most of the coal is burned for power generation, but substantial quantities are also employed in the manufacture of steel, chemicals, and activated carbons. Coal has a positive impact upon many industries, including mining, power, rail transportation, manufacturing, chemical, steel, activated carbon, and fuels. Everything that is in the earth’s crust is also present within coal to some extent, and the challenge is always to utilize abundant domestic coal in clean and environmentally friendly manners. In the case of the rare earths, these valuable and extraordinarily useful elements are present within the abundant coal and coal by-products produced domestically and world-wide. These materials include the coals, as well as the combustion by-products such as ashes, coal preparation wastes, gasification slags, and mining by-products. All of these materials can be viewed as potential sources of rare earth elements. Most of the common inorganic lanthanide compounds, such as the phosphates found in coal, have very high melting, boiling, and thermal decomposition temperatures, allowing them to concentrate in combustion and gasification by-products. Furthermore, rare earths have been found in interesting concentrations in the strata above and below certain coal seams. Much of the recent research on coal utilization in the United States has focused upon the capture of pollutants such as acid gases, particulates, and mercury, and the greenhouse gas carbon dioxide. The possible recovery of rare earth and other critical elements from abundant coal and by-products is an exciting new research area, representing a

  6. Novel applications of diagnostic x-rays in activating photo-agents through x-ray induced visible luminescence from rare-earth particles: an in vitro study

    NASA Astrophysics Data System (ADS)

    Abliz, Erkinay; Collins, Joshua E.; Friedberg, Joseph S.; Kumar, Ajith; Bell, Howard; Waynant, Ronald W.; Tata, Darrell B.

    2010-02-01

    Photodynamic agents such as Photofrin II (Photo II) utilized in photodynamic therapy (PDT) possess a remarkable property to become preferentially retained within the tumor's micro-environment. Upon the photo-agent's activation through visible light photon absorption, the agents exert their cellular cytotoxicity through type II and type I mechanistic pathways through extensive generation of reactive oxygen species (ROS): singlet oxygen 1O2, superoxide anion O2 -, and hydrogen peroxide H2O2, within the intratumoral environment. Unfortunately, due to shallow visible light penetration depth (~2mm to 5mm) in tissues, the PDT strategy currently has largely been restricted to the treatments of surface tumors, such as the melanomas. Additional invasive strategies through optical fibers are currently utilized in getting the visible light into the intended deep seated targets within the body for PDT. In this communication, we report on a novel strategy in utilizing "soft" energy diagnostic X-rays to indirectly activate Photo II through X-ray induced luminescence from Gadolinium oxysulfide (20 micron dimension) particles doped with Terbium: Gd2O2S:Tb. X-ray induced visible luminescence from Gd2O2S:Tb particles was spectroscopically characterized and the ROS production levels from clinically relevant concentration (10 μg/ml) of Photo II was quantified through changes in the Vitamin C absorbance. ROS kinetics through X-ray induced luminescence was found to be similar to the ROS kinetics from red He-Ne laser exposures used in the clinics. Taken together, in-vitro findings herein provide the basis for future studies in determining the safety and efficacy of this non-invasive X-ray induced luminescence strategy in activating photo-agent in deep seated tumors.

  7. Trimethylsilylmethyl complexes of the rare-earth metals with sterically hindered N-heterocyclic carbene ligands: adduct formation and C-H bond activation.

    PubMed

    Fegler, Waldemar; Spaniol, Thomas P; Okuda, Jun

    2010-08-07

    Tris(trimethylsilylmethyl) complexes of yttrium and lutetium [LnR(3)(THF)(2)] (R = CH(2)SiMe(3)) were treated with sterically bulky N-heterocyclic carbenes (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). IPr gave labile mono-adducts [LnR(3)(NHC)], isolated as thermally robust crystals and fully characterized by NMR spectroscopy and X-ray diffraction. IMes gave a similar lutetium mono-adduct [LuR(3)(IMes)] with the lutetium alkyl [LuR(3)(THF)(2)], whereas the yttrium alkyl [YR(3)(THF)(2)] resulted in the formation of an ortho-metalated product. This compound, isolated as a crystalline bis(THF) adduct, contains a strained six-membered chelate ring that has been formed by the C-H bond activation of one of the ortho-methyl groups of the mesityl group. In contrast [LuR(3)(IMes)] only slowly underwent a similar C-H bond activation.

  8. Catalytic enantioselective construction of tetrasubstituted carbons by self-assembled poly rare earth metal complexes.

    PubMed

    Shibasaki, Masakatsu; Kanai, Motomu

    2007-07-07

    Rare earth metal-based enantioselective catalysts that can promote practical cyanation reactions of ketones and ketoimines were developed. These catalytic enantioselective tetrasubstituted carbon-forming reactions are useful platforms for the synthesis of biologically active compounds. ESI-MS and crystallographic studies of the asymmetric catalysts revealed that the active catalysts are polymetallic complexes produced through the assembly of modules. The higher-order structure of the polymetallic complexes has strong effects on catalyst activity and enantioselectivity. Controlling the higher-order structure of artificial polymetallic asymmetric catalysts is a new strategy for optimizing asymmetric catalysts. Recent progress in this approach is also described.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    PubMed Central

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

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

  11. Origin of heavy rare earth mineralization in South China

    PubMed Central

    Xu, Cheng; Kynický, Jindřich; Smith, Martin P.; Kopriva, Antonin; Brtnický, Martin; Urubek, Tomas; Yang, Yueheng; Zhao, Zheng; He, Chen; Song, Wenlei

    2017-01-01

    Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are strongly depleted in Ce, implying high oxidation state. These REE minerals show higher initial Nd isotope than primary REE-rich minerals (ɛNd(t)=0.9±0.8 versus −11.5±0.5). The mineralized weathering crusts inherited REE signature of the granites, but show more Ce depletion and more overall concentration of the REE. We propose, therefore, that highly oxidized, REE-rich fluids, derived from external, isotopically depleted sources, metasomatized the granites, which resulted in Ce depletion as Ce4+ and enrichment of the remaining REE, especially the HREE, contributing to formation of a globally important REE resource. PMID:28220784

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  13. Proposal for laser cooling of rare-earth ions

    NASA Astrophysics Data System (ADS)

    Dulieu, Olivier; Hong, Ye; Wyart, Jean-François; Lepers, Maxence

    2016-05-01

    The efficiency of laser cooling relies on the existence of an almost closed optical-transition cycle in the energy spectrum of the considered species. In this respect, rare-earth elements exhibit many transitions which are likely to induce noticeable leaks from the cooling cycle. In this work, to determine whether laser cooling of singly ionized erbium Er+ is feasible, we have performed accurate electronic-structure calculations of energies and spontaneous-emission Einstein coefficients of Er+, using a combination of ab initio and least-squares-fitting techniques. We identify five weak closed transitions suitable for laser cooling, the broadest of which is in the kilohertz range. For the strongest transitions, by simulating the cascade dynamics of spontaneous emission, we show that repumping is necessary, and we discuss possible repumping schemes.We expect our detailed study on Er+ to give good insight into the laser cooling of neighboring ions such as Dy+. Supported by ``Agence Nationale de la Recherche'' (ANR), under the project COPOMOL (Contract No. ANR-13-IS04-0004-01).

  14. Artificially produced rare-earth free cosmic magnet

    PubMed Central

    Makino, Akihiro; Sharma, Parmanand; Sato, Kazuhisa; Takeuchi, Akira; Zhang, Yan; Takenaka, Kana

    2015-01-01

    Chemically ordered hard magnetic L10-FeNi phase of higher grade than cosmic meteorites is produced artificially. Present alloy design shortens the formation time from hundreds of millions of years for natural meteorites to less than 300 hours. Electron diffraction detects four-fold 110 superlattice reflections and a high chemical order parameter (S  0.8) for the developed L10-FeNi phase. The magnetic field of more than 3.5 kOe is required for the switching of magnetization. Experimental results along with computer simulation suggest that the ordered phase is formed due to three factors related to the amorphous state: high diffusion rates of the constituent elements at lower temperatures when crystallizing, a large driving force for precipitation of the L10 phase, and the possible presence of L10 clusters. Present results can resolve mineral exhaustion issues in the development of next-generation hard magnetic materials because the alloys are free from rare-earth elements, and the technique is well suited for mass production. PMID:26567704

  15. Solvent extraction of rare-earth metals by carboxylic acids

    SciTech Connect

    Preez, A.C. du; Preston, J.S.

    1992-04-01

    The solvent extraction of the trivalent lanthanides and yttrium from nitrate media by solutions of carboxylic acids in xylene has been studied. Commercially available carboxylic acids such as Versatic 10 and naphthenic acids were used, as well as model compounds of known structure, such as 2-ethylhexanoic and 3-cyclohexylpropanoic acids. In a few cases, extraction of the metals from sulphate and chloride solutions was also investigated. The dependence of the extraction properties of the carboxylic acids on the atomic number of the lanthanide shows a definite relationship to the steric bulk of the carboxylic acid molecule quantified by means of the steric parameter, E{sub s}{prime} of the substituent alkyl group. The stoichiometries of the extracted complexes for representative light (La), middle (Gd) and heavy (Lu) rare-earth metals were investigated by the slope-analysis technique for a sterically hindered acid (Versatic 10 acid; -E{prime}{sub s} = 3.83) and an acid with low steric hindrance (3-cyclohexylpropanoic acid; -E{prime}{sub s} = 0.28). 14 refs., 13 figs., 3 tabs.

  16. Magnetostriction of some rare earth-aluminum Laves phase compounds

    NASA Technical Reports Server (NTRS)

    Pourarian, F.; Wallace, W. E.

    1979-01-01

    Measurements of the linear and volume magnetostriction of RAl2 cubic Laves compounds in which R is one of the rare earth elements Gd, Dy, Ho or Er, at temperatures between 4.2 K and the Curie temperature of each compound, are reported. Magnetic fields up to 2.5 Tesla were applied, and magnetostriction was measured using standard strain gage techniques. Saturation magnetostrictions of 17 x 10 to the -6th, -1420 x 10 to the -6th, 60 x 10 to the -6th and -920 x 10 to the -6th are determined at 4.2 K for GdAl2, DyAl2, HoAl2 and ErAl2, respectively. Large forced magnetostriction is observed in GdAl2 above the saturation field and the strain temperature dependence shows a decrease in magnitude below 40 K. A linear dependence of magnetostriction on magnetic field was observed for DyAl2 above 40 K, and the observed temperature dependence is interpreted in terms of the lowest order single-ion magnetoelastic theory. An observed decrease in the magnitude of the strain of HoAl2 below 15 K is associated with a change of the easy direction of magnetization, while in the case of ErAl2, magnetostriction is observed to occur normally up to the Curie temperature. Large volume magnetostriction is obtained for all the compounds with the exception of GdAl2.

  17. Synthesis, structure, and physical properties of new rare earth ferrocenoylacetonates.

    PubMed

    Koroteev, Pavel S; Dobrokhotova, Zhanna V; Ilyukhin, Andrey B; Efimov, Nikolay N; Rouzières, Mathieu; Kiskin, Mikhail A; Clérac, Rodolphe; Novotortsev, Vladimir M

    2016-04-21

    New ferrocenoylacetonate complexes of several rare earth elements, [Ln(fca)3(bpy)]·MeC6H5 (Ln = Pr (), Eu (), Gd (), Tb (), Dy (), Ho (), Y (); bpy - 2,2'-bipyridine; Hfca - FcCOCH2COMe) as well as scandium ferrocenoylacetonate [Sc(fca)3]·0.5MeC6H5 (), were synthesized and characterized by single crystal X-ray diffraction analysis. In the crystal lattice of the isostructural complexes , two [Ln(fca)3(bpy)] molecules form a pair due to stacking interactions between the bpy ligands. The Ln(3+) ions are coordinated in a square antiprism geometry with a coordination number of 8. The Sc(3+) ions in complex are coordinated in an octahedral geometry. Thermolysis of complexes was studied under air and argon atmospheres; in the first case, it affords perovskites LnFeO3 as one of the products. Complexes display single-molecule magnet properties, and the effective relaxation barrier for the Dy complex , was found to be Δeff/kB = 241 K, which is one of the highest values obtained for a mononuclear β-diketonate lanthanide complex.

  18. Separation/Preconcentration Techniques for Rare Earth Elements Analysis

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    The main aim of this chapter exactly characterizes the contribution. The analytical chemistry of the rare earth elements (REEs) very often is highly complicated and the determination of a specific element is impossible without a sample pre-concentration. Sample preparation can be carried out either by separation of the REEs from the matrix or by concentrating the REEs. The separation of REEs from each other is mainly made by chromatography. At the beginning of REE analysis, the method of precipitation/coprecipitation was applied for the treatment of REE mixtures. The method is not applicable for the separation of trace amounts of REEs. The majority of the methods used are based on the distribution of REEs in a two-phase system, a liquid-liquid or a liquid-solid system. Various techniques have been developed for the liquid-liquid extraction (LLE), in particular the liquid phase micro-extraction. The extraction is always combined with a pre-concentration of the REEs in a single drop of extractant or in a hollow fiber filled with the extractant. Further modified techniques for special applications and for difficult REE separation have been developed. Compared to the LLE, the solid phase micro-extraction is preferred. The method is robust and easy to handle, in which the solid phase loaded with the REEs can be used directly for subsequent determination methods. At present, very new solid materials, like nanotubes, are developed and tested for solid phase extraction.

  19. Size distribution of rare earth elements in coal ash

    USGS Publications Warehouse

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

    2015-01-01

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

  20. Rare earth patterns in shergottite phosphates and residues

    NASA Technical Reports Server (NTRS)

    Laul, J. C.

    1987-01-01

    Leaching experiments with 1M HCl on ALHA 77005 powder show that rare earth elements (REE) are concentrated in accessory phosphate phases (whitlockite, apatite) that govern the REE patterns of bulk shergottites. The REE patterns of whitlockite are typically light REE-depleted with a negative Eu anomaly and show a hump at the heavy REE side, while the REE pattern of apatite (in Shergotty) is light REE-enriched. Parent magmas are calculated from the modal compositions of residues of ALHA 77005, Shergotty, and EETA 79001. The parent magmas lack a Eu anomaly, indicating that plagioclase was a late-stage crystallizing phase and that it probably crystallized before the phosphates. The parent magmas of ALHA 77005 and Shergotty have similar REE patterns, with a subchondritic Nd/Sm ratio. However, the Sm/Nd isotopoics require a light REE-depleted source for ALHA 77005 (if the crystallization age is less than 600 Myr) and a light REE-enriched source for Shergotty. Distant Nd and Sr isotopic signatures may suggest different source regions for shergottites.

  1. Origin of heavy rare earth mineralization in South China.

    PubMed

    Xu, Cheng; Kynický, Jindřich; Smith, Martin P; Kopriva, Antonin; Brtnický, Martin; Urubek, Tomas; Yang, Yueheng; Zhao, Zheng; He, Chen; Song, Wenlei

    2017-02-21

    Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are strongly depleted in Ce, implying high oxidation state. These REE minerals show higher initial Nd isotope than primary REE-rich minerals (ɛNd(t)=0.9±0.8 versus -11.5±0.5). The mineralized weathering crusts inherited REE signature of the granites, but show more Ce depletion and more overall concentration of the REE. We propose, therefore, that highly oxidized, REE-rich fluids, derived from external, isotopically depleted sources, metasomatized the granites, which resulted in Ce depletion as Ce(4+) and enrichment of the remaining REE, especially the HREE, contributing to formation of a globally important REE resource.

  2. A novel sequential process for remediating rare-earth wastewater.

    PubMed

    Cui, Mingcan; Jang, Min; Kang, Kyounglim; Kim, Dukmin; Snyder, Shane A; Khim, Jeehyeong

    2016-02-01

    A novel and economic sequential process consisting of precipitation, adsorption, and oxidation was developed to remediate actual rare-earth (RE) wastewater containing various toxic pollutants, including radioactive species. In the precipitation step, porous air stones (PAS) containing waste oyster shell (WOS), PASWOS, was prepared and used to precipitate most heavy metals with >97% removal efficiencies. The SEM-EDS analysis revealed that PAS plays a key role in preventing the surface coating of precipitants on the surface of WOS and in releasing the dissolved species of WOS successively. For the adsorption step, a polyurethane (PU) impregnated by coal mine drainage sludge (CMDS), PUCMDS, was synthesized and applied to deplete fluoride (F), arsenic (As), uranium (U), and thorium (Th) that remained after precipitation. The continuous-mode sequential process using PAS(WOS), PU(CMDS), and ozone (O3) had 99.9-100% removal efficiencies of heavy metals, 99.3-99.9% of F and As, 95.8-99.4% of U and Th, and 92.4% of COD(Cr) for 100 days. The sequential process can treat RE wastewater economically and effectively without stirred-tank reactors, pH controller, continuous injection of chemicals, and significant sludge generation, as well as the quality of the outlet met the EPA recommended limits.

  3. Origin of heavy rare earth mineralization in South China

    NASA Astrophysics Data System (ADS)

    Xu, Cheng; Kynický, Jindřich; Smith, Martin P.; Kopriva, Antonin; Brtnický, Martin; Urubek, Tomas; Yang, Yueheng; Zhao, Zheng; He, Chen; Song, Wenlei

    2017-02-01

    Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are strongly depleted in Ce, implying high oxidation state. These REE minerals show higher initial Nd isotope than primary REE-rich minerals (εNd(t)=0.9+/-0.8 versus -11.5+/-0.5). The mineralized weathering crusts inherited REE signature of the granites, but show more Ce depletion and more overall concentration of the REE. We propose, therefore, that highly oxidized, REE-rich fluids, derived from external, isotopically depleted sources, metasomatized the granites, which resulted in Ce depletion as Ce4+ and enrichment of the remaining REE, especially the HREE, contributing to formation of a globally important REE resource.

  4. Revisiting the rare earth elements in foraminiferal tests [rapid communication

    NASA Astrophysics Data System (ADS)

    Haley, Brian A.; Klinkhammer, Gary P.; Mix, Alan C.

    2005-10-01

    Are the rare earth elements (REEs) in foraminifera a valuable proxy for use in paleoceanographic and climate change studies? In order to investigate this, we attempted a comprehensive study of REEs in planktonic and benthic foraminifera. Several different cleaning protocols were tested. Although the hydroxylamine used to clean all foraminifera in this study removes an unidentified source of REE contamination, it seems to remobilize metal oxides that are otherwise unaffected in flow-through dissolution. The calculated REE distribution coefficients, KD(REE)s, are between 100 and 500 for both planktonic and benthic foraminifera. These KDs are high compared to other elements in biogenic calcite but can be explained through a general model of element incorporation during foraminiferal calcification. From data taken from eight core tops in the southeast Pacific, we conclude that the REEs in planktonic foraminifera are, indeed, useful as a proxy for upper ocean water mass and mixed layer biogenic productivity. Alternatively, the REEs in benthic foraminifera are useful as a proxy for carbon flux to the sea floor. These proxies should be robust down core unless the sediments have undergone anoxic diagenesis, which stabilizes Fe carbonate thus overprinting the primary REE signature. However, it is clear from REE distributions in foraminiferal tests if anoxic conditions have occurred.

  5. Rare earth doped upconverting particles for different photonic applications

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab; Gangadharan, Ajith Kumar; Sardar, Dhiraj Kumar

    2013-03-01

    Trivalent rare earth ions especially erbium (Er3+) and ytterbium (Yb3+) co-doped in various host nanoparticles are known for their extraordinary spectroscopic properties. A thorough optical characterization including the absolute upconversion quantum yield (QY) measurement is of critical importance in evaluating their potential for various photonic applications. In this paper, we will be presenting a measured absolute upconversion QYs for Yb3+ and Er3+ doped in La2O2S under 980 and 1550 nm excitation at various power densities. Comparison of absolute QYs for different concentrations of Yb3+ and Er3+ doped in La2O2S will be made for all the upconversion emissions with respect to reported most efficient upconverting phosphor NaYF4 doped with 20% Yb3+ and 2% Er3+. Furthermore, applications of these phosphors in different areas such as bio-imaging, solar cell, security, etc. will be explored depending on the measured absolute upconversion quantum yields. In addition, preliminary results on in vitro imaging using upconverting nanoparticles as a contrast agent will be reported. This work was supported by the National Science Foundation Partnerships for Research and Education in Materials (PREM) Grant No. DMR-0934218.

  6. Complex magnetic properties in multilayer rare earth oxypnictides

    NASA Astrophysics Data System (ADS)

    Wang, Jiakui; Marcinkova, Andrea; Chen, Chih-Wei; Morosan, Emilia; Morosan Group Team

    2014-03-01

    Intensive research interest on layered transition metal pnictide materials was stimulated by the discovery of high temperature superconductivity in Fe-pnictides a few years ago. To study the relationship between superconductivity, crystal structure and magnetism, and to search for novel superconductors of better application potential, more transition metal pnictides are worth investigating. In this talk, I will discuss physical properties of members of a particular class of layered oxypnictides, with four transition metal pnictogen layers per unit cell. While varying the rare earth ion, we find that one compound is a low temperature superconductor (Tc 1.7 K), and others show diverse magnetic properties, including ferromagnetic or antiferromagnetic order, or spin glass behavior. I will show our observation from measurements of DC and AC magnetization, specific heat and resistivity. The understanding of the physical properties of these isostructual compounds may serve as a guide in the search for superconductivity in these systems. This work is supported by MURI-AFOSR and Rice University.

  7. Spectroscopy of Luminescent Crystals Containing Rare Earth Elements

    NASA Astrophysics Data System (ADS)

    Chen, Meng-Ling; Lii, Kwang-Hwa; Chang, Bor-Chen

    2013-06-01

    We have studied the spectroscopy of luminescent crystals containing rare earth elements such as KEuGe_2O_6, Cs_3EuSi_6O_{15}, K_4[(UO_2)Eu_2(Ge_2O_7)_2], and R_2(C_8H_{10}O_4)_3 (R= Y, Tb, or Eu). The emission and excitation spectra of these compounds were recorded at ambient temperature. These spectra are consistent with the structures which were determined by single crystal X-ray diffraction. Crystals containing hybrid luminescent centers were also synthesized and interesting energy transfer mechanisms were observed. For example, dramatic luminescence quenching was found in KEu_xNd_{1-x}Ge_2O_6 (x= 0.98, 0.96, 0.94, and 0.84) as well as in Cs_3Eu_{0.98}Nd_{0.02}Si_6O_{15}, while different compositions of Y_xEu_yTb_{2-x-y}(C_8H_{10}O_4)_3 exhibit different emission colors. Emission lifetimes were also measured for these compounds, and the results shed light on the energy transfer mechanisms. Detailed results of our research will be presented. P.-L. Chen, P.-Y. Chiang, H.-C. Yeh, B.-C. Chang, and K.-H. Lii, Dalton Trans., 1721 (2008). M.-Y. Hung, Y.-H. Chen, B.-C. Chang, and K.-H. Lii, Chem. Mater. 17, 5743 (2005).

  8. Spin Hall torques generated by rare-earth thin films

    NASA Astrophysics Data System (ADS)

    Reynolds, Neal; Jadaun, Priyamvada; Heron, John T.; Jermain, Colin L.; Gibbons, Jonathan; Collette, Robyn; Buhrman, R. A.; Schlom, D. G.; Ralph, D. C.

    2017-02-01

    We report an initial experimental survey of spin Hall torques generated by the rare-earth metals Gd, Dy, Ho, and Lu, along with comparisons to first-principles calculations of their spin Hall conductivities. Using spin torque ferromagnetic resonance (ST-FMR) measurements and dc-biased ST-FMR, we estimate lower bounds for the spin Hall torque ratio, ξSH, of ≈0.04 for Gd, ≈0.05 for Dy, ≈0.14 for Ho, and ≈0.014 for Lu. The variations among these elements are qualitatively consistent with results from first principles [density-functional theory (DFT) in the local density approximation with a Hubbard-U correction]. The DFT calculations indicate that the spin Hall conductivity is enhanced by the presence of the partially filled f orbitals in Dy and Ho, which suggests a strategy to further strengthen the contribution of the f orbitals to the spin Hall effect by shifting the electron chemical potential.

  9. Pulsed field magnetization in rare-earth kagome systems.

    PubMed

    Hoch, M J R; Zhou, H D; Mun, E; Harrison, N

    2016-02-03

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd(3+) is a Kramers ion while Pr(3+) is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  10. X-ray Absorption Spectroscopy of the Rare Earth orthophosphates

    SciTech Connect

    Shuh, D.K.; Terminello, L.J.; Boatner, L.A.; Abraham, M.M.

    1993-06-01

    X-ray Absorption Spectroscopy (XAS) of the Rare Earth (RE) 3d levels yields sharp peaks near the edges as a result of strong, quasi-atomic 3d{sup 10}4f{sup n} {yields} 3d-{sup 9}4f{sup n+1} transitions and these transitions exhibit a wealth of spectroscopic features. The XAS measurements of single crystal REPO{sub 4} (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er) at the 3d edge were performed in the total yield mode at beam line 8-2 at the Stanford Synchrotron Radiation Laboratory (SSRL). The XAS spectra of the RE ions in the orthophosphate matrix generally resemble the XAS of the corresponding RE metal. This is not unexpected and emphasizes the major contribution of the trivalent state to the electronic transitions at the RE 3d edges. These spectra unequivocally identify the transitions originating from well-characterized RE cores and correlate well with previous theoretical investigations.

  11. Rare-earth dichloro and bis(alkyl) complexes supported by bulky amido-imino ligand. Synthesis, structure, reactivity and catalytic activity in isoprene polymerization.

    PubMed

    Kissel, Alexander A; Lyubov, Dmitry M; Mahrova, Tatyana V; Fukin, Georgy K; Cherkasov, Anton V; Glukhova, Tatyana A; Cui, Dongmei; Trifonov, Alexander A

    2013-07-07

    A monoanionic amido-imino ligand system [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)](-) was successfully employed for the synthesis of monomeric dichloro [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]LnCl2(THF)2 (Ln = Y, 2Y; Lu, 2Lu) and bis(alkyl) [(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Ln(CH2SiMe3)2(THF) (Ln = Y, 4Y; Lu, 4Lu) species of yttrium and lutetium. Dichloro complexes 2Y and 2Lu turned out to be unstable in aromatic solvents. The ligand symmetrization reaction in the case of 2Y affords the yttrium complex coordinated by dianionic [(2,6-iPr2C6H3)NC(=CH2)C(=CH2)N(C6H3-2,6-iPr2)](2-) ligand, (2,6-iPr2C6H3)N=C(Me)C(Me)=N(C6H3-2,6-iPr2) and YCl3. On the contrary, bis(alkyl) species 4Y and 4Lu are rather stable and do not undergo such a transformation or thermal decomposition. The treatment of complex 4Y with DME resulted in C-O bond cleavage and the formation of a dimeric methoxy-alkyl species {[(2,6-iPr2C6H3)N=C(Me)C(=CH2)N(C6H3-2,6-iPr2)]Y(CH2SiMe3)(μ-OMe)}2 (5). The ternary systems 4Ln/AliBu3/borate (borate = [HNMe2Ph][B(C6F5)4] and [CPh3][B(C6F5)4]; molar ratio 1 : 10 : 1) performed high catalytic activity in isoprene polymerization and ability to convert into polymer 1000-5000 equivalents of isoprene in 20-120 min with quantitative conversion. The obtained polyisoprenes possessed high molecular weights (2.9 × 10(4)-4.1 × 10(4)) and moderate polydispersities (2.14-3.52). Predominant 3,4-regioselectivity (up to 78%) was observed.

  12. Synthesis of metastable rare-earth-iron mixed oxide with the hexagonal crystal structure

    NASA Astrophysics Data System (ADS)

    Nishimura, Tatsuya; Hosokawa, Saburo; Masuda, Yuichi; Wada, Kenji; Inoue, Masashi

    2013-01-01

    Rare-earth-iron mixed oxides with the rare earth/iron ratio=1 have either orthorhombic (o-REFeO3) or hexagonal (h-REFeO3) structure. h-REFeO3 is a metastable phase and the synthesis of h-REFeO3 is usually difficult. In this work, the crystallization process of the precursors obtained by co-precipitation and Pechini methods was investigated in detail to synthesize h-REFeO3. It was found that the crystallization from amorphous to hexagonal phase and the phase transition from hexagonal to orthorhombic phase occurred at a similar temperature range for rare earth elements with small ionic radii (Er-Lu, Y). For both co-precipitation and Pechini methods, single-phase h-REFeO3 was obtained by shortening the heating time during calcination process. The hexagonal-to-orthorhombic phase transition took place by a nucleation growth mechanism and vermicular morphology of the thus-formed orthorhombic phase was observed. The hexagonal YbFeO3 had higher catalytic activity for C3H8 combustion than orthorhombic YbFeO3.

  13. Rare Earth Metal-Mediated Precision Polymerization of Vinylphosphonates and Conjugated Nitrogen-Containing Vinyl Monomers.

    PubMed

    Soller, Benedikt S; Salzinger, Stephan; Rieger, Bernhard

    2016-02-24

    This review focuses on introducing and explaining the rare earth metal-mediated group transfer polymerization (REM-GTP) of polar monomers and is composed of three main sections: poly(vinylphosphonate)s, surface-initiated group transfer polymerization (SI-GTP), and extension to N-coordinating Michael-type monomers (2-vinylpridine (2VP), 2-isopropenyl-2-oxazoline (IPOx)). The poly(vinylphosphonate)s section is divided into two parts: radical, anionic, and silyl ketene acetal group transfer polymerization (SKA-GTP) of vinylphosphonates in comparison to REM-GTP, and properties of poly(vinylphosphonate)s. The mechanism of vinylphosphonate REM-GTP is discussed in detail for initiation and propagation including activation enthalpies ΔH(‡) and entropies ΔS(‡) according to the Eyring equation. SI-GTP is presented as a method for surface functionalization, and recent trends for 2VP and IPOx polymerization are summarized. This review will serve as a good resource or guideline for researchers who are currently working in the field of rare earth metal mediated polymerization catalysis as well as for those who are interested in beginning to employ rare earth metal complexes for the synthesis of new materials from polar monomers.

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

    NASA Astrophysics Data System (ADS)

    Eduafo, Patrick Max

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

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

    PubMed

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

    2013-06-14

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

  16. Molten metal containment vessel with rare earth oxysulfide protective coating thereon and method of making same

    DOEpatents

    Krikorian, Oscar H.; Curtis, Paul G.

    1992-01-01

    An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.

  17. 78 FR 42974 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-18

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same... the sale within the United States after importation of certain sintered rare earth magnets, methods...

  18. Hydrothermal method of synthesis of rare-earth tantalates and niobates

    DOEpatents

    Nyman, May D; Rohwer, Lauren E.S.; Martin, James E

    2012-10-16

    A hydrothermal method of synthesis of a family of rare-earth Group 5 oxides, where the Group 5 oxide is a niobate or tantalate. The rare-earth Group 5 oxides can be doped with suitable emitter ions to form nanophosphors.

  19. The impact of rare earth cobalt permanent magnets on electromechanical device design

    NASA Technical Reports Server (NTRS)

    Fisher, R. L.; Studer, P. A.

    1979-01-01

    Specific motor designs which employ rare earth cobalt magnets are discussed with special emphasis on their unique properties and magnetic field geometry. In addition to performance improvements and power savings, high reliability devices are attainable. Both the mechanism and systems engineering should be aware of the new performance levels which are currently becoming available as a result of the rare earth cobalt magnets.

  20. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  1. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  3. 40 CFR 421.270 - Applicability: Description of the primary rare earth metals subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  4. Direct evidence of the anisotropy of magnetization in rare-earth metals and rare-earth/Fe2 alloys

    NASA Astrophysics Data System (ADS)

    Benito, L.; Dumesnil, K.; Ward, R. C. C.

    2014-08-01

    We report on the genuine origin of the anisotropy of the magnetization M in rare-earth (RE) metals and RE-based alloys. Taking Ho-based layered nanostructures as testing ground, we prove that the anisotropy of M is substantial despite that the sixfold magnetic anisotropy constant K66 vanishes, which contradicts the established wisdom [E. R. Callen and H. B. Callen, J. Phys. Chem. Solids 16, 310 (1960), 10.1016/0022-3697(60)90161-X]. Furthermore, we show that the symmetric anisotropic contributions to M and K66 vary with temperature distinctively from one another, which indicates that both anisotropic effects are unrelated and stem from dissimilar microscopic sources. Our findings are discussed according to the theory [R. J. Elliott and M. F. Thorpe, J. Appl. Phys. 39, 802 (1968), 10.1063/1.2163622] that predicts the emergence of symmetric anisotropic indirect-exchange terms under the presence of orbital moments. We show evidence that the anisotropy of M is caused by the indirect-exchange coupling among localized 4f magnetic moments mediated by spin-orbit coupled conduction electrons, which ultimately generates a spatially nonuniform spin polarization that replicates the lattice symmetry.

  5. High-temperature desulfurization of gasifier effluents with rare earth and rare earth/transition metal oxides

    SciTech Connect

    Dooley, Kerry M.; Kalakota, Vikram; Adusumilli, Sumana

    2011-02-11

    We have improved the application of mixed rare-earth oxides (REOs) as hot gas desulfurization adsorbents by impregnating them on stable high surface area supports and by the inclusion of certain transition metal oxides. We report comparative desulfurization experiments at high temperature (900 K) using a synthetic biomass gasifier effluent containing 0.1 vol % H2S, along with H2, CO2, and water. More complex REO sorbents outperform the simpler CeO2/La2O3 mixtures, in some cases significantly. Supporting REOs on Al2O3 (~20 wt % REO) or ZrO2 actually increased the sulfur capacities found after several cycles on a total weight basis. Another major increase in sulfur capacity took place when MnOx or FeOx is incorporated. Apparently most of the Mn or Fe is dispersed on or near the surface of the mixed REOs because the capacities with REOs greatly exceeded those of Al2O3-supported MnOx or FeOx alone at these conditions. In contrast, incorporating Cu has little effect on sulfur adsorption capacities. Both the REO and transition metal/REO adsorbents could be regenerated completely using air for at least five repetitive cycles.

  6. Application of Freeze-Dried Powders of Genetically Engineered Microbial Strains as Adsorbents for Rare Earth Metal Ions.

    PubMed

    Moriwaki, Hiroshi; Masuda, Reiko; Yamazaki, Yuki; Horiuchi, Kaoru; Miyashita, Mari; Kasahara, Jun; Tanaka, Tatsuhito; Yamamoto, Hiroki

    2016-10-12

    The adsorption behaviors of the rare earth metal ions onto freeze-dried powders of genetically engineered microbial strains were compared. Cell powders obtained from four kinds of strains, Bacillus subtilis 168 wild type (WT), lipoteichoic acid-defective (ΔLTA), wall teichoic acid-defective (ΔWTA), and cell wall hydrolases-defective (EFKYOJLp) strains, were used as an adsorbent of the rare earth metal ions at pH 3. The adsorption ability of the rare earth metal ions was in the order of EFKYOJLp > WT > ΔLTA > ΔWTA. The order was the same as the order of the phosphorus quantity of the strains. This result indicates that the main adsorption sites for the ions are the phosphate groups and the teichoic acids, LTA and WTA, that contribute to the adsorption of the rare earth metal ions onto the cell walls. The contribution of WTA was clearly greater than that of LTA. Each microbial powder was added to a solution containing 16 kinds of rare earth metal ions, and the removals (%) of each rare earth metal ion were obtained. The scandium ion showed the highest removal (%), while that of the lanthanum ion was the lowest for all the microbial powders. Differences in the distribution coefficients between the kinds of lanthanide ions by the EFKYOJLp and ΔWTA powders were greater than those of the other strains. Therefore, the EFKYOJLp and ΔWTA powders could be applicable for the selective extraction of the lanthanide ions. The ΔLTA powder coagulated by mixing with a rare earth metal ion, although no sedimentation of the WT or ΔWTA powder with a rare earth metal ion was observed under the same conditions. The EFKYOJLp powder was also coagulated, but its flocculating activity was lower than that of ΔLTA. The ΔLTA and EFKYOJLp powders have a long shape compared to those of the WT or ΔWTA strain. The shapes of the cells will play an important role in the sedimentation of the microbial powders with rare earth metal ions. As the results, three kinds of the genetically

  7. Troubling toys: rare-Earth magnet ingestion in children causing bowel perforations.

    PubMed

    Mandhan, Parkash; Alsalihi, Muthana; Mammoo, Saleem; Ali, Mansour J

    2014-01-01

    Ingestion of foreign bodies in the pediatric population is common and magnet ingestion is known to cause a significant morbidity. Rare-earth magnets are small 3-6 mm diameter spherical powerful magnets that are sold as popular desk toys for adults and were previously found in construction toys in attractive colors for children to play with. We describe 2 young healthy children who ingested rare-earth magnets Buckyballs while playing with these magnetic toys and later presented in emergency with acute abdomen. Abdominal imaging revealed several (26 and 5) pieces of rare-earth magnets in the bowel loops. Emergency surgical exploration revealed multiple gastrointestinal perforations and fistula formation at sites of bowel entrapment in between strong magnets apposed to one another. We highlight the potential dangers of rare-earth magnets in children and suggest increasing public awareness about risks involved in rare-earth magnets ingestion by children to overcome this serious public health issue.

  8. Rare earths: atmospheric signatures for oil-fired power plants and refineries.

    PubMed

    Olmez, I; Gordon, G E

    1985-09-06

    The concentration pattern of rare earth elements on fine airborne particles (less than 2.5 micrometers in diameter) is distorted from the crustal abundance pattern in areas influenced by emissions from oil-fired plants and refineries. For example, the ratio of lanthanum to samarium is often greater than 20 compared to a crustal ratio less than 6. The unusual pattern apparently results from the distribution of rare earths in zeolite catalysts used in refining oil. Oil industry emissions perturb the rare earth pattern even at remote locations such as the Mauna Loa Observatory in Hawaii. Rare earth ratios are probably better for long-range tracing of oil emissions than vanadium and nickel concentrations because the ratios of rare earths on fine particles are probably not influenced by deposition and other fractionating processes. Emissions from oil-fired plants can be differentiated from those of refineries on an urban scale by the much smaller amounts of vanadium in the latter.

  9. Novel polymerization catalysts and hydride clusters from rare-earth metal dialkyls.

    PubMed

    Nishiura, Masayoshi; Hou, Zhaomin

    2010-04-01

    This Review gives an overview on recent progress in the synthesis and chemistry of rare-earth metal dialkyl complexes bearing monoanionic ancillary ligands, with an emphasis on novel polymerization catalysts. These structurally well-defined and highly reactive compounds are prepared either by alkane elimination reactions between trialkyl rare-earth complexes and acidic neutral ligands, or by the metathetical reactions of rare-earth trihalides with the alkali metal salts of the corresponding ligands. On treatment with an appropriate borate compound, the dialkyl complexes are converted into the corresponding cationic monoalkyl species, which serve as excellent catalysts for the polymerization and copolymerization of a variety of olefins to yield a series of new polymer materials that exhibit novel properties. Alternatively, hydrogenation of the dialkyl rare-earth complexes with H(2) affords a new class of rare-earth polyhydride complexes with unique features in terms of both their structure and reactivity.

  10. Method for determination of small amounts of rare earths and thorium in phosphate rocks

    USGS Publications Warehouse

    Waring, C.L.; Mela, H.

    1953-01-01

    In laboratory investigations, interest developed in the possible rare-earth content of phosphate samples from Florida and the northwestern United States. Because of the difficulty of making chemical determinations of traces of individual rare earths, a combined chemical-spectrographic method was investigated. After removal of iron by the extraction of the chloride with ether, the rare earths and thorium are concentrated by double oxalate precipitation, using calcium as a carrier. The rare earths are freed from calcium by an ammonium hydroxide precipitation with a fixed amount of aluminum as a carrier. The aluminum also serves as an internal standard in the final spectrographic analysis. The method will determine from 0.02 to 2 mg. of each rare earth with an error no greater than 10%. The investigation has resulted in a fairly rapid and precise procedure, involving no special spectrographic setup. The method could be applied to other types of geologic materials with the same expected accuracy.

  11. Rare earth fluoride nano-/microstructures: hydrothermal synthesis, luminescent properties and applications.

    PubMed

    Zhao, Qian; Xu, Zhenhe; Sun, Yaguang

    2014-02-01

    Rare earth fluoride materials have attracted wide interest and come to the forefront in nanophotonics due to their distinct electrical, optical and magnetic properties as well as their potential applications in diverse fields such as optical telecommunication, lasers, biochemical probes, infrared quantum counters, and medical diagnostics. This review presents a comprehensive overview of the flourishing field of rare earth fluorides materials in the past decade. We summarize the recent research progress on the preparation, morphology, luminescent properties and application of rare earth fluoride-based luminescent materials by hydrothermal systems. Various rare earth fluoride materials are obtained by fine-tuning of experimental conditions, such as capping agents, fluoride source, acidity, temperature and reaction time. The controlled morphology, luminescent properties and application of the rare earth fluorides are briefly discussed with typical examples.

  12. Electronic and magnetic coupling between rare-earth adatoms and the Fe(001) surface

    SciTech Connect

    Carbone, C. ); Rochow, R. ); Braicovich, L. ); Jungblut, R. ); Kachel, T. ); Tillmann, D.; Kisker, E. )

    1990-02-15

    The spin-dependent electronic structure of monolayer coverages of rare-earth metals on Fe(001) has been studied by spin-resolved photoelectron spectroscopy with synchrotron radiation. The highly spin-polarized photoemission from the localized 4{ital f} levels of Gd, Tb, and Dy on Fe(001) reveals the antiparallel coupling between these heavy rare earths and the Fe spin moment. Exchange-split final-state multiplet terms of the 4{ital f} spectra of the heavy rare earths are explicitly distinguished by direct observation of opposite polarization. For 1 monolayer of the light rare-earth Nd on Fe(001) the rare-earth magnetic moment couples parallel to the Fe magnetic moment.

  13. Self-assemblies of luminescent rare earth compounds in capsules and multilayers.

    PubMed

    Zhang, Renjie; Shang, Juanjuan; Xin, Jing; Xie, Beibei; Li, Ya; Möhwald, Helmuth

    2014-05-01

    This review addresses luminescent rare earth compounds assembled in microcapsules as well as in planar films fabricated by the layer-by-layer (LbL) technique, the Langmuir-Blodgett (LB) method and in self-assembled monolayers. Chemical precipitation, electrostatic, van der Waals interactions and covalent bonds are involved in the assembly of these compounds. Self-organized ring patterns of rare earth complexes in Langmuir monolayers and on planar surfaces with stripe patterns, as well as fluorescence enhancement due to donor-acceptor pairs, microcavities, enrichment of rare earth compounds, and shell protection against water are described. Recent information on the tuning of luminescence intensity and multicolors by the excitation wavelength and the ratio of rare earth ions, respectively, are also reviewed. Potential applications of luminescent rare earth complex assemblies serving as biological probes, temperature and gas sensors are pointed out.

  14. Optical characterization of biological tissues and rare earth nanoparticles

    NASA Astrophysics Data System (ADS)

    Barrera, Frederick John, III

    The ubiquitous use of lasers as both a diagnostic and therapeutic tool for medical applications (e.g. laser surgery, photoacoustic imaging, photodynamic therapy etc.), had rendered the understanding of optical properties of a biological medium critically important. The development of biomedical devices for the purposes of imaging or treatment requires a detailed investigation of these properties. Indeed, diagnostic monitoring of blood in vivo depends on knowledge of the distribution of light due to scattering in a blood medium. In addition, many optical properties of tissues have not been investigated experimentally at many clinically relevant wavelengths. The quantification of the scattering and absorptive behavior of tissue and its interaction with electromagnetic radiation is still at the core of predicting the outcome of a desired clinical effect. Therefore, the first portion of this Dissertation is a thorough characterization of ocular tissues in vitro using reflectance and transmittance spectroscopic techniques and computational models to extract and enlist a systematic study at wavelengths in the visible spectral region. The Kubelka-Munk (KM), Inverse Adding Doubling (IAD), and Inverse Monte Carlo (IMC) methods were used to determine the absorption and scattering coefficients and contrasted. The second portion of this Dissertation is an investigation of the optical and spectroscopic properties of novel rare earth Y2O3 and Nd3+:Y2O 3nanoparticles in a blood medium. Reflectance and transmittance measurements were performed and the absorption and scattering properties for the nanoparticle/blood samples were determined by computational methods and compared. Absorption and emission of Y2O3 and Nd3+:Y 2O3nanoparticle/blood medium revealed their utility as biomarkers.

  15. Recovery and Separation of Rare Earth Elements Using Salmon Milt

    PubMed Central

    Takahashi, Yoshio; Kondo, Kazuhiro; Miyaji, Asami; Watanabe, Yusuke; Fan, Qiaohui; Honma, Tetsuo; Tanaka, Kazuya

    2014-01-01

    Recycling rare earth elements (REEs) used in advanced materials such as Nd magnets is important for the efficient use of REE resources when the supply of several REEs is limited. In this work, the feasibility of using salmon milt for REE recovery and separation was examined, along with the identification of the binding site of REEs in salmon milt. Results showed that (i) salmon milt has a sufficiently high affinity to adsorb REEs and (ii) the adsorption capacity of the milt is 1.04 mEq/g, which is comparable with that of commercial cation exchange resin. Heavier REEs have higher affinity for milt. A comparison of stability constants and adsorption patterns of REEs discussed in the literature suggests that the phosphate is responsible for the adsorption of REE in milt. The results were supported by dysprosium (Dy) and lutetium (Lu) LIII-edge extended x-ray absorption fine structure (EXAFS) spectroscopy. The REE-P shell was identified for the second neighboring atom, which shows the importance of the phosphate site as REE binding sites. The comparison of REE adsorption pattern and EXAFS results between the milt system and other adsorbent systems (cellulose phosphate, Ln-resin, bacteria, and DNA-filter hybrid) revealed that the coordination number of phosphate is correlated with the slope of the REE pattern. The separation column loaded with milt was tested to separate REE for the practical use of salmon milt for the recovery and separation of REE. However, water did not flow through the column possibly because of the hydrophobicity of the milt. Thus, sequential adsorption–desorption approach using a batch-type method was applied for the separation of REE. As an example of the practical applications of REE separation, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste by a batch-type method using salmon milt. PMID:25490035

  16. Rare Earth Doped IR Fiber Lasers For Medical Applications

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon; Allen, Roger

    1989-06-01

    Trivalent rare earth doped lasers in fluorozirconate glasses and fibers that lase between 2 and 3 μm are reviewed. There have been a large number of laser-fiber optic systems below 2pm developed for clinical microsurgery at a variety of sites. The required flexibility of the fiber optic waveguide varies with the clinical use, such as: intraocular (through a small diameter rigid tube), endoscopically accessible pulmonary and gastric mucosa (through a port of a fiber-optic endoscope of intermediate flexibility), and intra-arterial (as an integral part of a flexible catheter, which in the case of the coronaries must be very flexible so as to negotiate abrupt bends and bifurcations without damage to the vessels). Laser energy absorbed by tissue is capable of coagulation of tissue (denaturation of structural proteins), melting of fatty deposits or other structures (solid or gel to liquid phase transitions), as well as direct breakage of chemical bonds by high energy photons. It is of general interest to develop a pulsed laser system transmitted through flexible fiber optics that is capable of precise ablation of targeted tissue with minimal damage to the remaining tissue. Ideally, the device should be able to ablate any tissue because of the general absorptive properties of tissue, and not a specific chromophore such as melanin or hemoglobin, the concentration of which varies widely among tissues. Two obvious ubiquitous chromophores have been widely discussed: 1) proteins and nucleic acids whose high concentration and absorption coefficients lead to strong tissue absorption in the ultraviolet and 2) water whose strong infrared absorption bands have been widely utilized in CO2 laser surgery. Non-linear absorption occurring at very high power densities (~1 GW/cm2) has been shown to be very effective for non-invasive ocular (an optically transparent field) microsurgery at the image plane of a slit lamp, but this approach appears impractical in fiber optic systems because

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

    NASA Astrophysics Data System (ADS)

    Sindern, Sven; Meyer, F. Michael

    2016-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  19. Rare earth element analysis indicates micropollutants in an urban estuary

    NASA Astrophysics Data System (ADS)

    Mohajerin, T. J.; Johannesson, K. H.; Kolker, A.; Burdige, D. J.; Chevis, D.

    2011-12-01

    Rare earth element analysis of Bayou Bienvenue waters shows anomalously high gadolinium, Gd, concentrations relative to its nearest neighbors in the REE series, europium and terbium. The anomalously high Gd concentrations indicate anthropogenic input from waste-water treatment plants in the area as anthropogenic Gd input can be traced back to its use as a contrast agent in magnetic resonance imaging in hospitals. Others have shown that anomalously high levels of Gd in natural waters are likely to be associated with other micropollutants that also occur in hospital effluent and that are not removed in the wastewater treatment process, including pharmaceuticals in the form of steroids, antihistamines, and antibiotics. Estuaries serve as many important ecological roles and have been shown to act as a filter for pollutants. To better understand the transport, biogeochemical cycling, and ultimate fate of trace elements in estuaries, I collected surface water samples from Bayou Bienvenue, a wetland triangle that covers an area of 427 acres directly adjacent to New Orleans, Louisiana. Water samples from Bayou Bienvenue were collected along the salinity gradient and subsequently filtered through progressively smaller pore-size filters. The resulting fractions were analyzed for trace element concentions, including the REEs, by magnetic sector ICP-MS. The attached figure shows the Gd anomaly present in the particulate (>0.45μm) fraction. Upper continental crust (UCC)-normalized plots of colloidal REEs (0.02μm - 0.45μm) fraction is lacking this anomaly indicating anthropogenic Gd is found chiefly in the particulate fraction in Bayou Bienvenue. No clear relationship between Gd concentration and salinity was apparent.

  20. Attenuation of rare earth elements in a boreal estuary

    NASA Astrophysics Data System (ADS)

    Åström, Mats E.; Österholm, Peter; Gustafsson, Jon Petter; Nystrand, Miriam; Peltola, Pasi; Nordmyr, Linda; Boman, Anton

    2012-11-01

    This study focuses on attenuation of rare earth elements (REE) when a boreal creek, acidified and loaded with REE and other metals as a result of wetland drainage, empties into a brackish-water estuary (salinity < 6‰). Surface water was collected in a transect from the creek mouth to the outer estuary, and settling (particulate) material in sediment traps moored at selected locations in the estuary. Ultrafiltration, high-resolution ICP-MS and modeling were applied on the waters, and a variety of chemical reagents were used to extract metals from the settling material. Aluminium, Fe and REE transported by the acidic creek were extensively removed in the inner/central estuary where the acidic water was neutralised, whereas Mn was relatively persistent in solution and thus redistributed to particles and deposited further down the estuary. The REE removal was caused by several contemporary mechanisms: co-precipitation with oxyhydroxides (mainly Al but also Fe), complexation with flocculating humic substances and sorption to suspended particles. Down estuary the dissolved REE pool, remaining after removal, was fractionated: the <1 kDa pool became depleted in the middle REE and the colloidal (0.45 μm-1 kDa) pool depleted in the middle and heavy REE. This fractionation was controlled by the removal process, such that those REE with highest affinity for the settling particles became most depleted in the remaining dissolved pool. Modeling, based on Visual MINTEQ version 3.0 and the Stockholm Humic Model after revision and updating, predicted that the dissolved (<0.45 μm) REE pool in the estuary is bound almost entirely to humic substances. Acid sulphate soils, the source of the REE and other metals in the creek water, are widespread on coastal plains worldwide and therefore the REE attenuation patterns and mechanisms identified in the studied estuary are relevant for recognition of similar geochemical processes and conditions in a variety of coastal locations.

  1. Structural and Crystal Chemical Properties of Alkali Rare-earth Double Phosphates

    DOE PAGES

    Farmer, James Matthew; Boatner, Lynn A.; Chakoumakos, Bryan C.; ...

    2016-01-01

    When appropriately activated, alkali rare-earth double phosphates of the form: M3RE(PO4)2 (where M denotes an alkali metal and RE represents either a rare-earth element or Y or Sc) are of interest for use as inorganic scintillators for radiation detection at relatively long optical emission wavelengths. These compounds exhibit layered crystal structures whose symmetry properties depend on the relative sizes of the rare-earth and alkali-metal cations. Single-crystal X-ray and powder neutron diffraction methods were used here to refine the structures of the series of rare-earth double phosphate compounds: K3RE(PO4)2 with RE = Lu, Er, Ho, Dy, Gd, Nd, Ce, plus Ymore » and Sc - as well as the compounds: A3Lu(PO4)2, with A = Rb, and Cs. The double phosphate K3Lu(PO4)2 was reported and structurally refined previously. This material had a hexagonal unit cell at room temperature with the Lu ion six-fold coordinated with oxygen atoms of the surrounding phosphate groups. Additionally two lower-temperature phases were observed for K3Lu(PO4)2. The first phase transition to a monoclinic P21/m phase occurred at ~230 K, and the Lu ion retained its six-fold coordination. The second K3Lu(PO4)2 phase transition occurred at ~130 K. The P21/m space group symmetry was retained, however, one of the phosphate groups rotated to increase the oxygen coordination number of Lu from six to seven. This structure then became isostructural with the room-temperature form of the compound K3Yb(PO4)2 reported here that also exhibits an additional high-temperature phase which occurs at T = 120 °C with a transformation to hexagonal P-3 space group symmetry and a Yb-ion coordination number reduction from seven to six. This latter result was confirmed using EXAFS. The single-crystal growth methods structural systematics, and thermal expansion properties of the present series of alkali rare-earth double phosphates, as determined by X-ray and neutron diffraction methods, are treated here.« less

  2. Structural and Crystal Chemical Properties of Alkali Rare-earth Double Phosphates

    SciTech Connect

    Farmer, James Matthew; Boatner, Lynn A.; Chakoumakos, Bryan C.; Rawn, Claudia J.; Richardson, Jim

    2016-01-01

    When appropriately activated, alkali rare-earth double phosphates of the form: M3RE(PO4)2 (where M denotes an alkali metal and RE represents either a rare-earth element or Y or Sc) are of interest for use as inorganic scintillators for radiation detection at relatively long optical emission wavelengths. These compounds exhibit layered crystal structures whose symmetry properties depend on the relative sizes of the rare-earth and alkali-metal cations. Single-crystal X-ray and powder neutron diffraction methods were used here to refine the structures of the series of rare-earth double phosphate compounds: K3RE(PO4)2 with RE = Lu, Er, Ho, Dy, Gd, Nd, Ce, plus Y and Sc - as well as the compounds: A3Lu(PO4)2, with A = Rb, and Cs. The double phosphate K3Lu(PO4)2 was reported and structurally refined previously. This material had a hexagonal unit cell at room temperature with the Lu ion six-fold coordinated with oxygen atoms of the surrounding phosphate groups. Additionally two lower-temperature phases were observed for K3Lu(PO4)2. The first phase transition to a monoclinic P21/m phase occurred at ~230 K, and the Lu ion retained its six-fold coordination. The second K3Lu(PO4)2 phase transition occurred at ~130 K. The P21/m space group symmetry was retained, however, one of the phosphate groups rotated to increase the oxygen coordination number of Lu from six to seven. This structure then became isostructural with the room-temperature form of the compound K3Yb(PO4)2 reported here that also exhibits an additional high-temperature phase which occurs at T = 120 °C with a transformation to hexagonal P-3 space group symmetry and a Yb-ion coordination number reduction from seven to six. This latter result was confirmed using EXAFS. The single

  3. Modeling Activities in Earth Science

    NASA Astrophysics Data System (ADS)

    Malone, Kathy

    2014-05-01

    Students usually find science to be quite abstract. This is especially true of disciplines like Earth Science where it is difficult for the students to conduct and design hands-on experiments in areas such as Plate Tectonics that would allow them to develop predictive models. In the United States the new Next Generation Science Standards explicitly requires students to experience the science disciplines via modeling based activities. This poster presentation will discuss an activity that demonstrates how modeling, plate tectonics and student discourse converge in the earth science classroom. The activities featured on the poster will include using cardboard and shaving cream to demonstrate convergent plate boundaries, a Milky Way candy bar to demonstrate divergent boundaries and silly putty to demonstrate a strike slip boundary. I will discuss how students report back to the group about the findings from the lab and the techniques that can be used to heighten the student discourse. The activities outlined in this poster were originally designed for a middle school Earth Science class by Suzi Shoemaker for a graduate thesis at Arizona State University.

  4. [Effects of arbuscular mycorrhizal fungi on the growth and rare earth elements uptake of soybean grown in rare earth mine tailings].

    PubMed

    Guo, Wei; Zhao, Ren-xin; Zhao, Wen-jing; Fu, Rui-ying; Guo, Jiang-yuan; Zhang, Jun

    2013-05-01

    A greenhouse pot experiment was conducted to investigate the influence of arbuscular mycorrhizal (AM) fungi Glomus versiforme on the plant growth, nutrient uptake, C: N: P stoichiometric, uptake of heavy metals and rare earth elements by soybean (Glycine max) grown in rare earth mine tailings. The aim was to provide a basis for the revegetation of rare earth mine tailings. The results indicated that soybean had a high mycorrhizal colonization and symbiotic associations were successfully established with G. versiforme, with an average rate of approximately 67%. The colonization of G. versiforme significantly promoted the growth of soybean, increased P, K contents, and decreased C: N: P ratios, supporting the growth rate hypothesis. Inoculation with G. versiforme significantly decreased shoots and roots La, Ce, Pr and Nd concentrations of soybean compared to the control treatment. However, inoculation with G. versiforme had no significant effect on the heavy metal concentrations, except for significantly decreased shoot Fe and Cr concentrations and increased root Cd concentrations. The experiment demonstrates that AM fungi have a potential role for soybean to adapt the composite adversity of rare earth tailings and play a positive role in revegetation of rare earth mine tailings. Further studies on the role of AM fungi under natural conditions should be conducted.

  5. Carbonatite and alkaline intrusion-related rare earth element deposits–A deposit model

    USGS Publications Warehouse

    Verplanck, Philip L.; Van Gosen, Bradley S.

    2011-01-01

    The rare earth elements are not as rare in nature as their name implies, but economic deposits with these elements are not common and few deposits have been large producers. In the past 25 years, demand for rare earth elements has increased dramatically because of their wide and diverse use in high-technology applications. Yet, presently the global production and supply of rare earth elements come from only a few sources. China produces more than 95 percent of the world's supply of rare earth elements. Because of China's decision to restrict exports of these elements, the price of rare earth elements has increased and industrial countries are concerned about supply shortages. As a result, understanding the distribution and origin of rare earth elements deposits, and identifying and quantifying our nation's rare earth elements resources have become priorities. Carbonatite and alkaline intrusive complexes, as well as their weathering products, are the primary sources of rare earth elements. The general mineral deposit model summarized here is part of an effort by the U.S. Geological Survey's Mineral Resources Program to update existing models and develop new descriptive mineral deposit models to supplement previously published models for use in mineral-resource and mineral-environmental assessments. Carbonatite and alkaline intrusion-related REE deposits are discussed together because of their spatial association, common enrichment in incompatible elements, and similarities in genesis. A wide variety of commodities have been exploited from carbonatites and alkaline igneous rocks, such as rare earth elements, niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Other enrichments include manganese, strontium, tantalum, thorium, vanadium, and uranium.

  6. Distribution characteristics of rare earth elements in children's scalp hair from a rare earths mining area in southern China.

    PubMed

    Tong, Shi-Lu; Zhu, Wang-Zhao; Gao, Zhao-Hua; Meng, Yu-Xiu; Peng, Rui-Ling; Lu, Guo-Cheng

    2004-01-01

    In order to demonstrate the validity of using scalp hair rare earth elements (REEs) content as a biomarker of human REEs exposure, data were collected on REEs exposure levels from children aged 11-15 years old and living in an ion-adsorptive type light REEs (LREEs) mining and surrounding areas in southern China. Sixty scalp hair samples were analyzed by ICP-MS for 16 REEs (La Lu, Y and Sc). Sixteen REEs contents in the samples from the mining area (e.g., range: La: 0.14-6.93 microg/g; Nd: 0.09-5.27 microg/g; Gd: 12.2-645.6ng/g; Lu: 0.2-13.3 ng/g; Y: 0.03-1.27 microg/g; Sc: 0.05-0.30 microg/g) were significantly higher than those from the reference area (range: La: 0.04-0.40 microg/g; Nd: 0.04-0.32 microg/g; Gd: 8.3-64.6 ng/g; Lu: 0.4-3.3ng/g; Y: 0.03-0.29 microg/g; Sc: 0.11-0.36 microg/g) and even much higher than those published in the literature. The distribution pattern of REEs in scalp hair from the mining area was very similar to that of REEs in the mine and the atmosphere shrouding that area. In conclusion, the scalp hair REEs contents may indicate not only quantitatively but also qualitatively (distribution pattern) the absorption of REEs from environmental exposure into human body. The children living in this mining area should be regarded as a high-risk group with REEs (especially LREEs) exposure, and their health status should be examined from a REEs health risk assessment perspective.

  7. Rare earth element budgets in subduction-zone fluids

    NASA Astrophysics Data System (ADS)

    Tsay, A.; Zajacz, Z.; Sanchez-Valle, C.

    2012-12-01

    Subduction zone fluids play a fundamental role in the geochemical cycle of the Earth. The nature and composition of these fluids are determined by complex processes and still poorly understood. As a result of a variety of metasomatic and partial melting events, arc-related magmas display a typical trace element abundance spectrum, in which the rare earth elements' (REE) signature is an important record of petrogenetic processes. Therefore, investigating the behavior of REE in fluids at high pressure (P) and temperature (T) conditions is crucial for constraining fluid composition, as well as understanding subduction-zone processes in general. However, up to date, the experimental studies on REE solubility and speciation are limited to quite low P-T conditions (300 °C, saturated water vapor pressure) [1]. The theoretical predictions of the stability of REE complexes have been performed up to 350 °C [2] and 1000 °C, 0.5 GPa [3] by the extrapolation of thermodynamic data obtained at ambient conditions. In this study we present new experimental data on REE silicate (REE2Si2O7) solubility in aqueous quartz saturated fluids, containing various ligands, at conditions relevant for subducting slabs (600, 700, 800 °C, 2.6 GPa). The aim of the experiments was to investigate the relative effect of temperature and ligands on the solubility of REE. The experiments were conducted in an end-loaded piston-cylinder apparatus and the fluids were in situ sampled at P-T in the form of primary fluid inclusions in quartz [4]. The gold capsule was typically loaded with a chip of synthetic REE silicate (La,Nd,Gd,Dy,Er,Yb)2Si2O7, an aqueous fluid (~20 wt.%) and a piece of natural quartz. During the experiment (24-48 h) a thermal gradient along the capsule promoted intensive dissolution of quartz at the hottest part and precipitation of new quartz at the cooler part of the capsule, allowing the primary fluid inclusions to be trapped (~30-50 μm). Rubidium and cesium were added to the

  8. Investigating Rare Earth Element Systematics in the Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.

    2014-12-01

    The lanthanide series of elements (the 14 rare earth elements, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 μg/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our

  9. Modelling of Rare Earth Elements Complexation With Humic Acid

    NASA Astrophysics Data System (ADS)

    Pourret, O.; Davranche, M.; Gruau, G.; Dia, A.

    2006-12-01

    The binding of rare earth elements (REE) to humic acid (HA) was studied by combining Ultrafiltration and ICP- MS techniques. REE-HA complexation experiments were performed at various pH conditions (ranging from 2 to 10.5) using a standard batch equilibration method. Results show that the amount of REE bound to HA strongly increase with increasing pH. Moreover, a Middle REE (MREE) downward concavity is evidenced by REE distribution patterns at acidic pH. Modelling of the experimental data using Humic Ion Binding Model VI provided a set of log KMA values (i.e. the REE-HA complexation constants specific to Model VI) for the entire REE series. The log KMA pattern obtained displays a MREE downward concavity. Log KMA values range from 2.42 to 2.79. These binding constants are in good agreement with the few existing datasets quantifying the binding of REE with humic substances except a recently published study which evidence a lanthanide contraction effect (i.e. continuous increase of the constant from La to Lu). The MREE downward concavity displayed by REE-HA complexation pattern determined in this study compares well with results from REE-fulvic acid (FA) and REE-acetic acid complexation studies. This similarity in the REE complexation pattern shapes suggests that carboxylic groups are the main binding sites of REE in HA. This conclusion is further supported by a detailed review of published studies for natural, organic-rich, river- and ground-waters which show no evidence of a lanthanide contraction effect in REE pattern shape. Finally, application of Model VI using the new, experimentally determined log KMA values to World Average River Water confirms earlier suggestions that REE occur predominantly as organic complexes (> 60 %) in the pH range between 5-5.5 and 7-8.5 (i.e. in circumneutral pH waters). The only significant difference as compared to earlier model predictions made using estimated log KMA values is that the experimentally determined log KMA values

  10. Reverse engineering nuclear properties from rare earth abundances in the r process

    NASA Astrophysics Data System (ADS)

    Mumpower, M. R.; McLaughlin, G. C.; Surman, R.; Steiner, A. W.

    2017-03-01

    The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or r process of nucleosynthesis. The solar r-process residuals show a small peak in the rare earths around A∼ 160, which is proposed to be formed dynamically during the end phase of the r process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main r process. We explore the formation of the rare earth peak from the perspective of an inverse problem, using Monte Carlo studies of nuclear masses to investigate the unknown nuclear properties required to best match rare earth abundance sector of the solar isotopic residuals. When nuclear masses are changed, we recalculate the relevant β-decay properties and neutron capture rates in the rare earth region. The feedback provided by this observational constraint allows for the reverse engineering of nuclear properties far from stability where no experimental information exists. We investigate a range of astrophysical conditions with this method and show how these lead to different predictions in the nuclear properties influential to the formation of the rare earth peak. We conclude that targeted experimental campaigns in this region will help to resolve the type of conditions responsible for the production of the rare earth nuclei, and will provide new insights into the longstanding problem of the astrophysical site(s) of the r process.

  11. Dissolution of functional materials and rare earth oxides into pseudo alveolar fluid.

    PubMed

    Takaya, Mitsutoshi; Shinohara, Yasushi; Serita, Fumio; Ono-Ogasawara, Mariko; Otaki, Noriko; Toya, Tadao; Takata, Ayako; Yoshida, Katsumi; Kohyama, Norihiko

    2006-10-01

    The dissolution rates of rare earth oxides and two types of rare earth containing functional materials into water, saline solution, and Gamble's fluid were measured in order to evaluate the biological effects of rare earth-containing functional materials. The tested materials were yttrium, lanthanum, cerium and neodymium oxides, and neodymium-boron-iron magnet alloy (NdBFe) and lanthanum-mish-metal-nickel-cobalt (LmNiCo) hydrogen-containing alloy. The dissolution rates of the rare earth oxides were very low, resulting in concentrations of rare earth elements in the test solutions of the order of ppb. In the most extreme case, Gamble's fluid dissolved 1,400 times more of the rare earth oxides than pure water. Fairly high concentration of neodymium were found in the dissolving fluids, which means that trace neodymium present as an impurity in each rare earth oxide dissolved preferentially. For yttrium oxide, the ratio of neodymium to yttrium that dissolved in the saline solution was greater than 78,000 to 1, taking into account the amount of each that was originally present in the yttrium oxide.

  12. Synthesis of Chiral Aminocyclopropanes by Rare-Earth-Metal-Catalyzed Cyclopropene Hydroamination.

    PubMed

    Teng, Huai-Long; Luo, Yong; Wang, Baoli; Zhang, Liang; Nishiura, Masayoshi; Hou, Zhaomin

    2016-12-05

    The search for efficient and selective routes for the synthesis of chiral aminocyclopropane derivatives is of great interest and importance as these structures are important components of biologically active natural products and pharmaceuticals. We herein report the enantioselective intermolecular hydroamination of substituted cyclopropenes with various amines catalyzed by chiral half-sandwich rare-earth-metal complexes. This method constitutes a 100 % atom-efficient route for the synthesis of a variety of chiral α-aminocyclopropane derivatives in high yields (up to 96 %) and excellent stereoselectivity (up to >20:1 d.r. and 99 % ee) under mild reaction conditions (25 °C).

  13. Optical spectra of triply-charged rare-earth ions in polycrystalline corundum

    NASA Astrophysics Data System (ADS)

    Kaplyanskiĭ, A. A.; Kulinkin, A. B.; Kutsenko, A. B.; Feofilov, S. P.; Zakharchenya, R. I.; Vasilevskaya, T. N.

    1998-08-01

    Solid samples of polycrystalline corundum α-Al2O3 activated by triply-charged rare-earth ions RE3+ (R=Eu3+, Er3+, Pr3+) were synthesized by the sol-gel technology. Characteristic narrow-line optical absorption and luminescence spectra produced by intraconfigurational 4 f-4 f transitions in RE3+ ions have been measured. RE3+ ions have been established to form one dominant type of optical centers in the corundum matrix, and the energy diagram of Eu3+ and Er3+ Stark levels in corundum has been determined.

  14. Standardless EDXRF application for quantification of thorium (Th), uranium (U) and rare earth elements (REEs) in various Malaysian rare earth ores

    NASA Astrophysics Data System (ADS)

    Ruf, Mohd Izzat Fahmi Mohd; Bahri, Che Nor Aniza Che Zainul; AL-Areqi, Wadeeah M.; Majid, Amran Ab.

    2016-11-01

    Our local rare earth ores contained substantial amount of Thorium and Uranium which the level exceed permissible limit adopted by Malaysia and many importing nation. X-ray fluorescence technique has been applied for determination of thorium (Th), uranium (U) and rare earth elements (REEs) in Malaysian rare earth ores as it's recognized as viable tool. XRF has been widely used in detecting elemental composition of unknown materials both qualitative and quantitatively because of its wide range of element detection alongside the non-destructive analytical technique with great accuracy and precision. Four types of minerals sample which is monazite, xenotime, ilmenite and zircon were collected from `amang' factory located in famous city of mining, Ipoh and analyzed using EDXRF.

  15. Prospective analysis of the flows of certain rare earths in Europe at the 2020 horizon.

    PubMed

    Rollat, Alain; Guyonnet, Dominique; Planchon, Mariane; Tuduri, Johann

    2016-03-01

    This paper proposes a forecast of certain rare earth flows in Europe at the 2020 horizon, based on an analysis of trends influencing various actors of the rare earth industry along the value chain. While 2020 is indicated as the forecast horizon, the analysis should be considered as more representative of the next decade. The rare earths considered here are used in applications that are important for a low-carbon energy transition and/or have a significant recycling potential: NdFeB magnets (Pr, Nd, Dy), NiMH batteries (Pr, Nd) and fluorescent lamp phosphors (Eu, Tb, Y). An analysis of major trends affecting the rare earth industry in Europe along the value chain (including extraction, separation, fabrication, manufacture, use and recycling), helps to build a scenario for a material flow analysis of these rare earths in Europe. The scenario assumes in particular that during the next decade, there exists a rare earth mine in production in Europe (with Norra Kärr in Sweden as a most likely candidate) and also that recycling is in line with targets proposed in recent European legislation. Results are presented in the form of Sankey diagrams which help visualize the various flows for the three applications. For example, calculations forecast flows from extraction to separation of Pr, Nd and Dy for magnet applications in Europe, on the order of 310 tons, 980 tons and 80 tons rare earth metal resp., while recycled flows are 35 tons, 110 tons and 30 tons resp. Calculations illustrate how the relative contribution of recycling to supply strongly depends on the situation with respect to demand. Considering the balance between supply and demand, it is not anticipated any significant shortage of rare earth supply in Europe at the 2020 horizon, barring any new geopolitical crisis involving China. For some heavy rare earths, supply will in fact largely outweigh demand, as for example Europium due to the phasing out of fluorescent lights by LEDs.

  16. Biogeochemistry of the rare-earth elements with particular reference to hickory trees

    USGS Publications Warehouse

    Robinson, W.O.; Bastron, H.; Murata, K.J.

    1958-01-01

    Hickory trees concentrate the rare-earth elements in their leaves to a phenomenal degree and may contain as much as 2300 p.p.m. of total rare earths based on the dry weight of the leaves. The average proportions of the individual elements (atomic percent of the total rare-earth elements) in the leaves are: Y 36, La 16, Ce 14, Pr 2, Nd 20, Sm 1, Eu 0.7, Gd 3, Tb 0.6, Dy 3, Ho 0.7, Er 2, Tm 0.2, Yb 1, and Lu 0.2. The similarity in the proportions of the rare-earth elements in the leaves and in the exchange complex of the soil on which the hickory trees grow indicates that the trees do not fractionate the rare earths appreciably. The variation of the rare-earth elements in the leaves and soils can be explained generally in terms of the relative abundance of the cerium group and the yttrium group, except for the element cerium. The large fluctuations in the proportion of cerium [Ce/(La + Nd) atomic ratios of 0.16 to 0.86] correlate with oxidation-reduction conditions in the soil profile. The substitution of dilute H2SO3 for dilute HC1 in the determination of available rare-earth elements brings about a large increase in the proportion of cerium that is extracted from an oxygenated subsoil. These relationships strongly suggest that quadrivalent cerium is present in oxygenated subsoil and is less available to plants than the other rare-earth elements that do not undergo such a change in valence. A few parts per billion of rare-earth elements have been detected in two samples of ground water. ?? 1958.

  17. Review of rare earth element concentrations in oil shales of the Eocene Green River Formation

    USGS Publications Warehouse

    Birdwell, Justin E.

    2012-01-01

    Concentrations of the lanthanide series or rare earth elements and yttrium were determined for lacustrine oil shale samples from the Eocene Green River Formation in the Piceance Basin of Colorado and the Uinta Basin of Utah. Unprocessed oil shale, post-pyrolysis (spent) shale, and leached shale samples were examined to determine if oil-shale processing to generate oil or the remediation of retorted shale affects rare earth element concentrations. Results for unprocessed Green River oil shale samples were compared to data published in the literature on reference materials, such as chondritic meteorites, the North American shale composite, marine oil shale samples from two sites in northern Tibet, and mined rare earth element ores from the United States and China. The Green River oil shales had lower rare earth element concentrations (66.3 to 141.3 micrograms per gram, μg g-1) than are typical of material in the upper crust (approximately 170 μg g-1) and were also lower in rare earth elements relative to the North American shale composite (approximately 165 μg g-1). Adjusting for dilution of rare earth elements by organic matter does not account for the total difference between the oil shales and other crustal rocks. Europium anomalies for Green River oil shales from the Piceance Basin were slightly lower than those reported for the North American shale composite and upper crust. When compared to ores currently mined for rare earth elements, the concentrations in Green River oil shales are several orders of magnitude lower. Retorting Green River oil shales led to a slight enrichment of rare earth elements due to removal of organic matter. When concentrations in spent and leached samples were normalized to an original rock basis, concentrations were comparable to those of the raw shale, indicating that rare earth elements are conserved in processed oil shales.

  18. Strontium isotopes and rare-earth element geochemistry of hydrothermal carbonate deposits from Lake Tanganyika, East Africa

    SciTech Connect

    Barrat, J.A.; Boulegue, J.; Tiercelin, J.J.; Lesourd, M.

    2000-01-01

    At Cape Banza (North Tanganyika Lake), fluids and aragonite chimneys have been collected many times since the discovery of this sublacustrine field in 1987. This sampling has been investigated here for the Sr isotopic compositions and the rare-earth element features of the carbonates and a few fluid samples. The {sup 87}Sr/{sup 86}Sr ratios of the chimneys indicate that they have precipitated from a mixture of lake water (more than 95%) and hydrothermal fluids. No zoning in the chimneys was detected with the Sr data. For the rare-earth elements, the situation is more complex. The external walls of the chimneys are rare-earth-element-poor (La {approx} 500 ppb, Yb {approx} 200 ppb, La/Yb = 2 to 3.4). Their shale normalized rare-earth element patterns suggest that they are in equilibrium with the inferred carbonate-depositing fluids. The rare-earth element concentrations of the internal walls of the chimneys are significantly light rare earth elements (LREE)-enriched with La contents sometimes up to 5 ppm. The authors suggest that they contain more vent-fluid rare-earth elements than the external wall samples, possibly adsorbed on the surface of growing crystals or simply hosted by impurities. It was not possible to constrain the nature of these phases, but the variations of the compositions of the internal wall materials of the active chimneys with time, as well as data obtained on an inactive chimney indicate that this rare-earth element excess is mobile. Partition coefficients were calculated between the external wall aragonite and carbonate-depositing fluid. The results are strikingly similar to the values obtained by Sholkovitz and Shen (1995) on coral aragonite, and suggest that there is no significant biologic effect on the incorporation of rare-earth elements into coral aragonite and that the various carbonate complexes involved Me(CO{sub 3}{sup +}) complexes are the main LREE carriers in seawater instead of Me(CO{sub 3}){sub 2}{sup {minus}} in Banza fluids

  19. Rare-Earth Metals and Their Applications in Aviation

    DTIC Science & Technology

    1984-08-01

    promethium , samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium. Based on the...yttrium. Aside from these, promethium is an artifical element, it has radioactivity and is almost non-existent in the earth’s crust. The term "rate-earth

  20. Platinum-rare earth cathodes for direct borohydride-peroxide fuel cells

    NASA Astrophysics Data System (ADS)

    Cardoso, D. S. P.; Santos, D. M. F.; Šljukić, B.; Sequeira, C. A. C.; Macciò, D.; Saccone, A.

    2016-03-01

    Hydrogen peroxide (H2O2) is being actively investigated as an oxidant for direct borohydride fuel cells. Herein, platinum-rare earth (RE = Sm, Dy, Ho) alloys are prepared by arc melting and their activity for hydrogen peroxide reduction reaction (HPRR) is studied in alkaline media. Cyclic voltammetry and chronoamperometry measurements show that Pt-Sm electrode displays the highest catalytic activity for HPRR with the lowest activation energy, followed by Pt-Ho, while Pt-Dy alloys show practically no activity. Laboratory direct borohydride-peroxide fuel cells (DBPFCs) are assembled using these alloys. The DBPFC with Pt-Sm cathode gives the highest peak power density of 85 mW cm-2, which is more than double of that obtained in a DBPFC with Pt electrodes.

  1. Monolithic integration of rare-earth oxides and semiconductors for on-silicon technology

    SciTech Connect

    Dargis, Rytis Clark, Andrew; Erdem Arkun, Fevzi; Grinys, Tomas; Tomasiunas, Rolandas; O'Hara, Andy; Demkov, Alexander A.

    2014-07-01

    Several concepts of integration of the epitaxial rare-earth oxides into the emerging advanced semiconductor on silicon technology are presented. Germanium grows epitaxially on gadolinium oxide despite lattice mismatch of more than 4%. Additionally, polymorphism of some of the rare-earth oxides allows engineering of their crystal structure from hexagonal to cubic and formation of buffer layers that can be used for growth of germanium on a lattice matched oxide layer. Molecular beam epitaxy and metal organic chemical vapor deposition of gallium nitride on the rare-earth oxide buffer layers on silicon is discussed.

  2. Direct experimental evidence for the Ruderman-Kittel-Kasuya-Yosida interaction in rare-earth metals.

    PubMed

    Hindmarch, A T; Hickey, B J

    2003-09-12

    We show that the ferromagnetic heavy rare-earth (RE) metals show a transport spin polarization at the Fermi level in the majority spin, whereas in ferromagnetic light rare earths it is in the minority spin. The sign of the polarization is in agreement with what is expected due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling formalism. We show that magnetotransport measurements on magnetic multilayer samples containing magnetic REs provide a unique opportunity to verify the RKKY coupling scheme in pure rare-earth metals, allowing us to probe both the sign and temperature dependence of the spin-density oscillation.

  3. PROCESS FOR SEPARATING YTTRIUM FROM THE RARE EARTHS BY SOLVENT EXTRACTION

    DOEpatents

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

    1963-11-12

    A process of isolating yttrium from other rare earths present together with it in aqueous solutions is presented. Yttrium and rare earths heavier than yttrium are first extracted with dialkyl phosphoric acid, after adjustment of the acidity to 2 N, and then back-extracted with 5-6 N mineral acid to form a strip solution. Thiocyanate is added to the strip solution and the rare earths heavier than yttrium are then selectively extracted with trialkyl phosphate, dialkyl phosphoric acid, alkyl phosphonate, or dialkyl aryl phosphonate, leaving the yttrium in the aqueous solution. (AEC)

  4. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

  5. Miocene Coral Skeleton Rare Earth Element Patterns Reflect River Discharge

    NASA Astrophysics Data System (ADS)

    Mertz-Kraus, R.; Brachert, T. C.; Jochum, K. P.

    2010-12-01

    Rare Earth Element (REE) patterns of modern coral skeletons usually reflect the REE composition of ambient seawater which is characterized by heavy REE enriched relative to light REE with NASC (North American Shale Composite) normalized La/Lu ratios of typically <0.4. The REE concentration in coral aragonite is enriched by 3 to 4 orders of magnitude compared to ambient seawater. Here we report trace element data including REE of coral skeletons of Late Miocene age (~9 Ma, Tortonian) from Crete (Eastern Mediterranean). Analyses were done using a 213 nm Nd:YAG laser coupled to an Element2 ICP-MS along the growth axis of the coral skeletons. The profiles show that Ba/Ca ratios have a seasonally induced pattern with high values around the winter months which are identified by δ18O analyses. REE/Ca ratios co-vary with Ba/Ca ratios. Since the Ba/Ca ratio is a proxy used to monitor river discharge, the co-variation suggests the REE/Ca ratio to be a proxy of comparable quality. NASC-normalized REE patterns of the Tortonian corals have negative Ce anomalies like modern corals. However, the Tortonian corals have REE patterns highly enriched in LREE with (La/Lu)N ratios of 4 to 30 which is 1 to 2 orders of magnitude higher compared to modern corals. Al concentrations are low (<10 ppm) and do not correlate with REE concentrations indicating an insignificant fraction of terrigenous material included in the skeleton. Applying distribution coefficients typical for modern corals, the REE composition of the Tortonian ambient water yields (La/Lu)N of about 2 to 16. This range can be explained by binary mixing of modern Eastern Mediterranean sea surface water ((La/Lu)N=0.35, sea surface salinity (SSS) ~38 ‰) with highly LREE-enriched river water ((La/Lu)N >3, salinity ~0.5 ‰) transporting suspended and colloid phases, also highly enriched, especially in LREE, at a ratio of ~9 (seawater):1 (river water). The river water component is considered because paleoenvironmental

  6. 77 FR 51046 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same; Notice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-23

    ... COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same; Notice... Trade Commission has received a complaint entitled Certain Sintered Rare Earth Magnets, Methods of... United States after importation of certain sintered rare earth magnets, methods of making same...

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

    PubMed

    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.

  8. Recovery of rare earth elements from the sulfothermophilic red alga Galdieria sulphuraria using aqueous acid.

    PubMed

    Minoda, Ayumi; Sawada, Hitomi; Suzuki, Sonoe; Miyashita, Shin-ichi; Inagaki, Kazumi; Yamamoto, Takaiku; Tsuzuki, Mikio

    2015-02-01

    The demand for rare earth elements has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare earth elements, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare earth metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells.

  9. Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments

    NASA Technical Reports Server (NTRS)

    Schwandt, Craig S.; McKay, Gordon A.

    1997-01-01

    Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both the basaltic glass and the enstatite. Rare earth element concentrations in the glass were determined by electron microprobe analysis with uncertainties less than two percent relative. Rare earth element concentrations in enstatite were determined by secondary ion mass spectrometry with uncertainties less than five percent relative. The resulting rare earth element partition signature for enstatite is similar to previous calculated and composite low-Ca pigeonite signatures, but is better defined and differs in several details. The partition coefficients are consistent with crystal structural constraints.

  10. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films

    NASA Astrophysics Data System (ADS)

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-04-01

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu3+ and Tb3+) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

  11. High Temperature Chemistry of Rare Earth Compounds: Dramatic Examples of Periodicity.

    ERIC Educational Resources Information Center

    Cater, E. David

    1978-01-01

    Reports that energy required to promote a 4f electron to the 5d level has a profound and predictable influence on the systematics of reactions involving conversion of rare earth atoms from combined to free states. (Author/MA)

  12. Rare Earth or Cosmic Zoo: Testing the Frequency of Complex Life in the Universe

    NASA Astrophysics Data System (ADS)

    Bains, W.; Schulze-Makuch, D.

    2017-02-01

    We propose how to test between two major hypotheses about the frequency of life in the universe (Rare Earth and Cosmic Zoo) using future remote sensing capabilities targeted at exoplanets and site visits of planetary bodies in our solar system.

  13. Bonding nature of rare-earth-containing lead-free solders

    NASA Astrophysics Data System (ADS)

    Ramirez, Ainissa G.; Mavoori, Hareesh; Jin, Sungho

    2002-01-01

    The ability of rare-earth-containing lead-free solders to wet and bond to silica was investigated. Small additions of Lu (0.5-2 wt. %) added to eutectic Sn-Ag or Au-Sn solder render it directly solderable to a silicon oxide surface. The bonding is attributed to the migration of the rare-earth element to the solder-silica interface for chemical reaction and the creation of an interfacial layer that contains a rare-earth oxide. It was found that additions of rare-earth materials did not significantly modify the solidification microstructure or the melting point. Such oxide-bondable solders can be useful for assembly of various optical communication devices.

  14. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films.

    PubMed

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-04-18

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu(3+) and Tb(3+)) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces.

  15. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    NASA Astrophysics Data System (ADS)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

  16. The United States’ Vulnerability to Coercion by China in the Rare Earths Market

    DTIC Science & Technology

    2012-12-14

    Scandium, Yttrium, Lanthanum, Cerium, Praseodymium, Neodymium , Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium...production, several of the heavier rare earth minerals such as Dysprosium, Neodymium , Erbium, and Terbium are projected to be in short supply which

  17. Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers

    NASA Astrophysics Data System (ADS)

    Sidiroglou, F.; Roberts, A.; Baxter, G.

    2016-04-01

    Rare-earth doped optical fibers have captivated the interest of many researchers around the world across the past three decades. The growth of this research field has been stimulated primarily through their application in optical communications as fiber lasers and amplifiers, although rare-earth doped optical fiber based devices are now finding important uses in many other scientific and industrial areas (for example, medicine, sensing, the military, and material processing). Such wide commercial interest has provided a strong incentive for innovative fiber designs, alternative glass compositions, and novel fabrication processes. A prerequisite for the ongoing progress of this research field is developing the capacity to provide high resolution information about the rare-earth dopant distribution profiles within the optical fibers. This paper constitutes a comprehensive review of the imaging techniques that have been utilized in the analysis of the distribution of the rare-earth ion erbium within the core of optical fibers.

  18. Effects of Rare-Earth Oxides on the Reliability of X7R Dielectrics

    NASA Astrophysics Data System (ADS)

    Sakabe, Yukio; Hamaji, Yukio; Sano, Harunobu; Wada, Nobuyuki

    2002-09-01

    The effects of rare-earth oxides, e.g., La, Nd, Sm, Dy and Yb, on the reliability of multilayer capacitors (MLCs) with X7R dielectrics and Ni electrodes were investigated. Microstructures of the dielectrics were analyzed by transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) in order to characterize the rare-earth ions. Incorporation of rare-earth ions to BaTiO3 ceramics depended on their ionic radius, resulting in different microstructures and electric performances of dielectrics. Dy ions provided BaTiO3 ceramics with ideal X7R characteristics and high reliability. The mechanism governing leakage current was discussed in terms of the voltage dependence of leakage current. Electric properties and related reliability of the capacitors were attributed to solubility, distribution of rare-earth oxides and their occupation site in BaTiO3.

  19. Fabrication of Superhydrophobic and Luminescent Rare Earth/Polymer complex Films

    PubMed Central

    Wang, Zefeng; Ye, Weiwei; Luo, Xinran; Wang, Zhonggang

    2016-01-01

    The motivation of this work is to create luminescent rare earth/polymer films with outstanding water-resistance and superhydrophobicity. Specifically, the emulsion polymerization of styrene leads to core particles. Then core-shell-structured polymer nanoparticles are synthesized by copolymerization of styrene and acrylic acid on the core surface. The coordination reaction between carboxylic groups and rare earth ions (Eu3+ and Tb3+) generates uniform spherical rare earth/polymer nanoparticles, which are subsequently complexed with PTFE microparticles to obtain micro-/nano-scaled PTFE/rare earth films with hierarchical rough morphology. The films exhibit large water contact angle up to 161° and sliding angle of about 6°, and can emit strong red and green fluorescence under UV excitation. More surprisingly, it is found that the films maintain high fluorescence intensity after submersed in water and even in aqueous salt solution for two days because of the excellent water repellent ability of surfaces. PMID:27086735

  20. Assessment of trading partners for China's rare earth exports using a decision analytic approach.

    PubMed

    He, Chunyan; Lei, Yalin; Ge, Jianping

    2014-01-01

    Chinese rare earth export policies currently result in accelerating its depletion. Thus adopting an optimal export trade selection strategy is crucial to determining and ultimately identifying the ideal trading partners. This paper introduces a multi-attribute decision-making methodology which is then used to select the optimal trading partner. In the method, an evaluation criteria system is established to assess the seven top trading partners based on three dimensions: political relationships, economic benefits and industrial security. Specifically, a simple additive weighing model derived from an additive utility function is utilized to calculate, rank and select alternatives. Results show that Japan would be the optimal trading partner for Chinese rare earths. The criteria evaluation method of trading partners for China's rare earth exports provides the Chinese government with a tool to enhance rare earth industrial policies.

  1. An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

    PubMed

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

    2015-07-06

    Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359.

  2. Origin of enhanced magnetization in rare earth doped multiferroic bismuth ferrite

    SciTech Connect

    Nayek, C.; Thirmal, Ch.; Murugavel, P.; Tamilselvan, A.; Balakumar, S.

    2014-02-21

    We report structural and magnetic properties of rare earth doped Bi{sub 0.95}R{sub 0.05} FeO{sub 3} (R = Y, Ho, and Er) submicron particles. Rare earth doping enhances the magnetization and the magnetization shows an increasing trend with decreasing dopant ionic radii. In contrast to the x-ray diffraction pattern, we have seen a strong evidence for the presence of rare earth iron garnets R{sub 3}Fe{sub 5}O{sub 12} in magnetization measured as a function of temperature, in selected area electron diffraction, and in Raman measurements. Our results emphasised the role of secondary phases in the magnetic property of rare earth doped BiFeO{sub 3} compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy.

  3. Assessment of Trading Partners for China's Rare Earth Exports Using a Decision Analytic Approach

    PubMed Central

    He, Chunyan; Lei, Yalin; Ge, Jianping

    2014-01-01

    Chinese rare earth export policies currently result in accelerating its depletion. Thus adopting an optimal export trade selection strategy is crucial to determining and ultimately identifying the ideal trading partners. This paper introduces a multi-attribute decision-making methodology which is then used to select the optimal trading partner. In the method, an evaluation criteria system is established to assess the seven top trading partners based on three dimensions: political relationships, economic benefits and industrial security. Specifically, a simple additive weighing model derived from an additive utility function is utilized to calculate, rank and select alternatives. Results show that Japan would be the optimal trading partner for Chinese rare earths. The criteria evaluation method of trading partners for China's rare earth exports provides the Chinese government with a tool to enhance rare earth industrial policies. PMID:25051534

  4. Dehydration of fructose to 5-hydroxymethylfurfural by rare earth metal trifluoromethanesulfonates in organic solvents.

    PubMed

    Wang, Fenfen; Shi, Ai-Wu; Qin, Xiao-Xia; Liu, Chun-Ling; Dong, Wen-Sheng

    2011-05-15

    The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) was investigated by using various rare earth metal trifluoromethanesulfonates, that is, Yb(OTf)(3), Sc(OTf)(3), Ho(OTf)(3), Sm(OTf)(3), Nd(OTf)(3) as catalysts in DMSO. It is found that the catalytic activity increases with decreasing ionic radius of rare earth metal cations. Among the examined catalysts, Sc(OTf)(3) exhibits the highest catalytic activity. Fructose conversion of 100% and a HMF yield of 83.3% are obtained at 120°C after 2h by using Sc(OTf)(3) as the catalyst. Moreover, the catalytic dehydration of fructose was also carried out in different solvents, for example, DMA, 1,4-dioxane, and a mixture of PEG-400 and water. The results show that among the solvents DMSO is the most efficient in promoting the dehydration of fructose to HMF, and no rehydration byproducts such as levulinic acid and formic acid are detected.

  5. Highly efficient non-rare-earth red emitting phosphor for warm white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Zhu, Haomiao; Lin, Chun Che; Luo, Wenqin; Shu, Situan; Liu, Zhuguang; Liu, Yongsheng; Kong, Jintao; Ma, En; Cao, Yongge; Liu, Ru-Shi; Chen, Xueyuan

    2014-07-01

    Mn4+-activated fluoride compounds, as an alternative to commercial (oxy)nitride phosphors, are emerging as a new class of non-rare-earth red phosphors for high-efficacy warm white LEDs. Currently, it remains a challenge to synthesize these phosphors with high photoluminescence quantum yields through a convenient chemical route. Herein we propose a general but convenient strategy based on efficient cation exchange reaction, which had been originally regarded only effective in synthesizing nano-sized materials before, for the synthesis of Mn4+-activated fluoride microcrystals such as K2TiF6, K2SiF6, NaGdF4 and NaYF4. Particularly we achieve a photoluminescence quantum yield as high as 98% for K2TiF6:Mn4+. By employing it as red phosphor, we fabricate a high-performance white LED with low correlated colour temperature (3,556 K), high-colour-rendering index (Ra=81) and luminous efficacy of 116 lm W-1. These findings show great promise of K2TiF6:Mn4+ as a commercial red phosphor in warm white LEDs, and open up new avenues for the exploration of novel non-rare-earth red emitting phosphors.

  6. Relative sensitivity of rare earth elements in spark-source mass spectrometry.

    PubMed

    Roaldset, E

    1970-07-01

    A method for calculating the relative sensitivity factors for the rare earth elements in geological material is outlined. A close correlation is found between the relative sensitivity factors calculated and isotopic mass and the first ionization potential for the elements. The points are grouped in the vicinity of a regression line, which may be used to determine the relative sensitivity factors for all the rare earth elements.

  7. Theoretical and Computational Studies of Rare Earth Substitutes: A Test-bed for Accelerated Materials Development

    SciTech Connect

    Benedict, Lorin X.

    2015-10-26

    Hard permanent magnets in wide use typically involve expensive Rare Earth elements. In this effort, we investigated candidate permanent magnet materials which contain no Rare Earths, while simultaneously exploring improvements in theoretical methodology which enable the better prediction of magnetic properties relevant for the future design and optimization of permanent magnets. This included a detailed study of magnetocrystalline anisotropy energies, and the use of advanced simulation tools to better describe magnetic properties at elevated temperatures.

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

    DOEpatents

    Fulton, John L.; Hoffmann, Markus M.

    2003-12-23

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

  9. Rare earth oxide fluoride nanoparticles and hydrothermal method for forming nanoparticles

    DOEpatents

    Fulton, John L [Richland, WA; Hoffmann, Markus M [Richland, WA

    2001-11-13

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

  10. Magnetic susceptibility study of the heavy rare-earth stannate pyrochlores

    NASA Astrophysics Data System (ADS)

    Bondah-Jagalu, V.; Bramwell, S. T.

    2001-11-01

    The series of magnetic rare earth pyrochlore stannates R2Sn2O7 (R = rare earth, except Ce and Pm) have been investigated by powder susceptibility measurements down to T =1.8 K. The results are compared to results for the analogous titanate series, which are well-known frustrated magnets. Unlike the titanates, the whole series can be formed in the cubic pyrochlore structure. Possible experimental advantages of studying the stannates are discussed.

  11. Electroluminescence spectra of rare-earth-doped ZnS 1-XSe X thin films

    NASA Astrophysics Data System (ADS)

    Miura, Noboru; Ogawa, Kiyoshi; Kobayashi, Shuko; Matsumoto, Hironaga; Nakano, Ryotaro

    1994-04-01

    Electroluminescence has been measured for ZnS 1- XSe X thin films doped with rare-earth ions. As X increases the band-gap energy of the host decreases. The emission levels of trivalent rare-earth ions are not observed when the band-gap energy is narrower than the excitation levels. This is because of the energy transfer between the host and the emission center.

  12. Rare Earth Doped Silica Nanoparticles via Thermolysis of a Single Source Metallasilsesquioxane Precursor

    PubMed Central

    Davies, Gemma-Louise; O’Brien, John; Gun’ko, Yurii K.

    2017-01-01

    Rare earth metal doped silica nanoparticles have significant advantages over traditional organic dyes and quantum dots. Silsesquioxanes are promising precursors in the production of silica nanoparticles by thermolysis, due to their structural similarities with silica materials. This manuscript describes the production of a new Eu3+-based metallasilsesquioxane species and its use as a single source precursor in the thermolytic production of luminescent rare earth metal doped silica nanoparticles with characteristic emission in the visible region of the spectrum. PMID:28378754

  13. (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements

    DTIC Science & Technology

    2016-02-02

    AFRL-AFOSR-VA-TR-2016-0091 (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements George...2012 – 31/10/2015 4. TITLE AND SUBTITLE (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements... Science and Eng., Raleigh, NC (Profs. Justin Schwartz and Carl C. Koch). Their team performed all manufacturing and experimental measurements. 14

  14. Luminescent properties of rare earth fully activated apatites, LiRE9(SiO4)6O2 (RE = Ce, Eu, and Tb): site selective crystal field effect.

    PubMed

    Kim, Donghyeon; Park, Doyoung; Oh, Namgyeong; Kim, Jaegyeom; Jeong, Euh Duck; Kim, Seung-Joo; Kim, Sungyun; Park, Jung-Chul

    2015-02-16

    Novel LiCe9(SiO4)6O2 and LiTb9(SiO4)6O2 compounds have been successfully synthesized, and the site selectivity and occupancy of activator ions have been estimated including LiEu9(SiO4)6O2 compound. The rare earth (RE) fully occupied compounds, as well as the RE partially occupied congeners are required for the assessment of site selectivity of RE (activator) ions in apatite-type compounds. The splitting energies of the 6H and 4F Wycoff positions of LiRE9(SiO4)6O2 (RE = Ce, Eu, and Tb) compounds are calculated based on crystal field theory: ΔECe(6H) = 3849.3 cm(-1), ΔECe(4F) = 4228.1 cm(-1), ΔEEu(6H) = 3870.0 cm(-1), ΔEEu(4F) = 4092.8 cm(-1), ΔETb(6H) = 3637.6 cm(-1), ΔETb(4F) = 4396.1 cm(-1), indicating that the splitting energy for the 4F site is larger than that for the 6H site in all compounds; thus the absorption energy is higher for the 6H site. In apatite-type LiRE9(SiO4)6O2 (RE = Ce, Eu, and Tb) compounds, the Ce(3+) ions predominantly occupy the 4F site associated with the absorption band around 300 nm at lower Ce(3+) concentration, and then enter the 6H site associated the absorption band around 245 nm. For the Eu(3+)-doped compounds, the 4F site and 6H site are mixed within the charge transfer band (CTB) between 220 and 350 nm. Eu(3+) ions initially preferentially occupy the 6H site (around 290 nm) at lower Eu(3+) concentration and subsequently enter the 4F site (around 320 nm) with increasing Eu(3+) concentration. For the Tb(3+)-doped compounds, the absorption due to the two different sites is mixed within f-d absorption band between 200 and 300 nm. At lower Tb(3+) concentration, the Tb(3+) ions enter favorably 6H site around 240 nm and then enter 4F site around 270 nm. These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

  15. Determination of rare earth elements in high purity rare earth oxides by liquid chromatography, thermionic mass spectrometry and combined liquid chromatography/thermionic mass spectrometry

    NASA Astrophysics Data System (ADS)

    Stijfhoorn, D. E.; Stray, H.; Hjelmseth, H.

    1993-03-01

    A high-performance liquid Chromatographie (HPLC) method for the determination of rare earth elements in rocks has been modified and used for the determination of rare earth elements (REE) in high purity rare earth oxides. The detection limit was 1-1.5 ng or 2-3 mg/kg when a solution corresponding to 0.5 mg of the rare earth oxide was injected. The REE determination was also carried out by adding a mixture of selected REE isotopes to the sample and analysing the collected HPLC-fractions by mass spectrometry (MS) using a thermionic source. Since the matrix element was not collected, interference from this element during the mass spectrometric analysis was avoided. Detection limits as low as 0.5 mg/kg could then be obtained. Detection limits as low as 0.05 mg/kg were possible by MS without HPLC-pre-separation, but this approach could only be used for those elements that were not affected by the matrix. Commercial samples of high purity Nd 2O 3, Gd 2O 3 and Dy 2O 3 were analysed in this study, and a comparison of results obtained by HPLC, combined HPLC/MS and direct MS are presented.

  16. EarthScope Content Module for IRIS Active Earth Monitor

    NASA Astrophysics Data System (ADS)

    McQuillan, P. J.; Welti, R.; Johnson, J. A.; Shiffman, C. R.; Olds, S. E.

    2012-12-01

    The Active Earth Monitor (AEM) is an interactive computer-based display for university lobbies, museums, visitor centers, schools and libraries. AEM runs in a standard Internet web browser in full screen mode. The display consists of a customizable set of content pages about plate tectonics, earthquakes, volcanoes and tsunamis. Low-cost and simple-to-implement, the Active Earth Monitor provides a way to engage audiences with earth science information without spending resources on a large exhibit. The EarthScope Active Earth Monitor content set highlights the connections between the landscape and the research and monitoring being conducted by EarthScope in partnership with regional monitoring networks. Modules consist of chapters that focus on What is EarthScope?, EarthScope Observatories, and EarthScope Research Results. Content topics are easily explored using a web page button type navigation interface via a touch screen or mouse. A formative evaluation of general public users informed the interface design. Chapters in the modules start with a general overview and proceed to detailed specifics. Each chapter utilizes at least one set of live or near real-time research data (often more than one). This exposes the general public to active ongoing research that is engaging, relevant to the individual user, and explained in easy to understand terms. All live content is updated each time a user accesses the individual page displaying the live data. Leading questions are presented allowing the user to examine the content before accessing the answer via pop-up box. Diagrams and charts of research data have explanatory keys that allow users to self explore all content. Content pages can be created and inserted in the Active Earth Monitor by utilizing the simple HTML/CSS coding.;

  17. China’s rare earth supply chain: Illegal production, and response to new cerium demand

    SciTech Connect

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-03-29

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China’s supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructed a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the U.S. market starting from 2018. Results showed that market share of the illegal sector has grown since 2007 to 2015, ranging between 22% and 25% of China’s rare earth supply, translating into 59–65% illegal heavy rare earths and 14–16% illegal light rare earths. There would be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Lastly, we illustrated revenue streams for different ore compositions in China in 2015.

  18. China's Rare Earth Supply Chain: Illegal Production, and Response to new Cerium Demand

    NASA Astrophysics Data System (ADS)

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-07-01

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China's supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructed a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the US market starting from 2018. Results showed that market share of the illegal sector has grown since 2007-2015, ranging between 22% and 25% of China's rare earth supply, translating into 59-65% illegal heavy rare earths and 14-16% illegal light rare earths. There will be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Finally, we illustrate revenue streams for different ore compositions in China in 2015.

  19. The studies of enhanced fluorescence in the two novel ternary rare-earth complex systems.

    PubMed

    Sun, Xiao-Jun; Li, Wen-Xian; Chai, Wen-Juan; Ren, Tie; Shi, Xiao-Yan

    2010-03-01

    Two novel ternary rare-earth complexes SmL(5).L'.(ClO(4))(2).7H(2)O and EuL(5).L'.(ClO(4))(2).6H(2)O (the first ligand L = C(6)H(5)COCH(2)SOCH(2)COC(6)H(5), the second ligand L' = C(6)H(4)OHCOO(-)) were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, (1)HNMR and UV spectra. The detailed luminescence studies on the rare-earth complexes showed that the ternary rare-earth complexes presented stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary rare-earth materials. After the introduction of the second ligand salicylic acid group, the relative emission intensities and fluorescence lifetimes of the ternary complexes LnL(5).L'.(ClO(4))(2).nH(2)O (Ln = Sm, Eu; n=7, 6) enhanced more obviously than the binary complexes LnL(5).(ClO(4))(3).2H(2)O. This indicated that the presence of both organic ligand bis(benzoylmethyl) sulfoxide and the second ligand salicylic acid could sensitize fluorescence intensities of rare-earth ions, and the introduction of salicylic acid group was a benefit for the fluorescence properties of the ternary rare-earth complexes. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed.

  20. China’s rare earth supply chain: Illegal production, and response to new cerium demand

    DOE PAGES

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-03-29

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China’s supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructedmore » a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the U.S. market starting from 2018. Results showed that market share of the illegal sector has grown since 2007 to 2015, ranging between 22% and 25% of China’s rare earth supply, translating into 59–65% illegal heavy rare earths and 14–16% illegal light rare earths. There would be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Lastly, we illustrated revenue streams for different ore compositions in China in 2015.« less

  1. Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy

    PubMed Central

    Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

    2010-01-01

    Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y2O3 and Yb2O3 could cause massive vacuolization. Y2O3 and Yb2O3 treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects. PMID:20856835

  2. Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

    NASA Astrophysics Data System (ADS)

    Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

    2014-11-01

    Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

  3. Nano rare-earth oxides induced size-dependent vacuolization: an independent pathway from autophagy.

    PubMed

    Zhang, Ying; Yu, Chenguang; Huang, Guanyi; Wang, Changli; Wen, Longping

    2010-09-07

    Four rare earth oxides have been shown to induce autophagy. Interestingly, we often noticed plentiful vacuolization, which was not always involved in this autophagic process. In this study, we investigated three other rare-earth elements, including Yttrium (Y), Ytterbium (Yb), and Lanthanum (La). Autophagic effect could be induced by all of them but only Y(2)O(3) and Yb(2)O(3) could cause massive vacuolization. Y(2)O(3) and Yb(2)O(3) treated by sonication or centrifugation to reduce particle size were used to test vacuolization level in HeLa cell lines. The results showed that rare earth oxides-induced vacuolization is size-dependent and differs from autophagic pathway. To further clarify the characteristics of this autophagic process, we used MEF Atg-5 (autophagy associated gene 5) knockout cell line, and the result showed that the autophagic process induced by rare earth oxides is Atg-5-dependent and the observed vacuolization was independent from autophagy. Similar results could also be observed in our tests on 3-methyladenine(3-MA), a well-known autophagy inhibitor. In conclusion, for the first time, we clarified the relationship between massive vacuolization and autophagic process induced by rare earth oxides and pointed out the size effect of rare earth oxides on the formation of vacuoles, which give clues to further investigation on the mechanisms underlying their biological effects.

  4. Rare-earth-doped bifunctional alkaline-earth metal fluoride nanocrystals via a facile microwave-assisted process.

    PubMed

    Pang, Min; Liu, Dapeng; Lei, Yongqian; Song, Shuyan; Feng, Jing; Fan, Weiqiang; Zhang, Hongjie

    2011-06-20

    Rare-earth-doped magnetic-optic bifunctional alkaline-earth metal fluoride nanocrystals have been successfully synthesized via a facile microwave-assisted process. The as-prepared nanocrystals were monodisperse and could form stable colloidal solutions in polar solvents, such as water and ethanol. They show bright-green fluorescence emisson. Furthermore, Gd(3+)-doped ones exhibit paramagnetic behavior at room temperature and superparamagnetic behavior at 2 K.

  5. Rare Isotopes in Cosmic Explosions and Accelerators on Earth

    ScienceCinema

    Schatz, Hendrick [Michigan State University, East Lansing, Michigan, United States

    2016-07-12

    Rare isotopes are nature’s stepping stones to produce the heavy elements, and they are produced in large quantities in stellar explosions. Despite their fleeting existence, they shape the composition of the universe and the observable features of stellar explosions. The challenge for nuclear science is to produce and study the very same rare isotopes so as to understand the origin of the elements and a range of astronomical observations. I will review the progress that has been made to date in astronomy and nuclear physics, and the prospects of finally addressing many of the outstanding issues with the future Facility for Rare Isotope Beams (FRIB), which DOE will build at Michigan State University.

  6. Interfacing broadband photonic qubits to on-chip cavity-protected rare-earth ensembles

    PubMed Central

    Zhong, Tian; Kindem, Jonathan M.; Rochman, Jake; Faraon, Andrei

    2017-01-01

    Ensembles of solid-state optical emitters enable broadband quantum storage and transduction of photonic qubits, with applications in high-rate quantum networks for secure communications and interconnecting future quantum computers. To transfer quantum states using ensembles, rephasing techniques are used to mitigate fast decoherence resulting from inhomogeneous broadening, but these techniques generally limit the bandwidth, efficiency and active times of the quantum interface. Here, we use a dense ensemble of neodymium rare-earth ions strongly coupled to a nanophotonic resonator to demonstrate a significant cavity protection effect at the single-photon level—a technique to suppress ensemble decoherence due to inhomogeneous broadening. The protected Rabi oscillations between the cavity field and the atomic super-radiant state enable ultra-fast transfer of photonic frequency qubits to the ions (∼50 GHz bandwidth) followed by retrieval with 98.7% fidelity. With the prospect of coupling to other long-lived rare-earth spin states, this technique opens the possibilities for broadband, always-ready quantum memories and fast optical-to-microwave transducers. PMID:28090078

  7. Some interesting phenomena in the study of rare earth long lasting phosphors

    NASA Astrophysics Data System (ADS)

    Su, Qiang; Li, Chengyu; Wang, Jing

    2014-09-01

    Long lasting phosphors (LLPs) are a kind of very important and usable luminescent materials. Many new LLPs were found and some interesting phenomena were observed. Some distinctive questions on LLPs have been found and reviewed in this paper. For example: why most of LLPs of rare earth cannot be excited by sun light even they have nearly the same excitation spectra as SrAl2O4:Eu2+, Dy3+, Sr2MgSi2O7:Eu2+, Dy3+ which can be excited by sun light ? why there is only the emission of the activator Eu2+ in SrAl2O4:Eu2+, Dy3+, but no emission of the codopant (Dy3+) was observed under usual excitation condition? why different co-dopants have different effect on the LLP? various mechanisms about LLP of rare earth are still discussing widely and unsolved, which is the suitable one? there is similarity between the mechanisms of thermo-stimulated luminescence (TSL), photo-stimulated luminescence (PSL) and force-stimulated luminescence (FSL or mechanoluminescence) with the mechanisms for long lasting luminescence. For synthesis of LLP, which is a kind of electron trapping materials, the aliovalence (unequal valence) substitution method plays the key role. By using of this method, defects, vacancies and traps are produced. The properties of LLP strongly depend on the effects of doping and co-doping ions and some applications of LLP are presented in this paper.

  8. Rare earth elements in soils from selected areas on the Island of Hawaii

    SciTech Connect

    Barnard, W.M.; Halbig, J.B.

    1985-07-01

    Fifty soil samples for the wet, windward (east) side and dry, leeward (west) side of the Island of Hawaii were analyzed for La, Ce, Sm, Eu, Yb, and Lu by neutron activation/gamma-ray spectroscopic analysis. Data on concentrations in each sample are listed and analyzed statistically for soil samples collected from the western slope of Kohala Mountain, the western coastal plain of Mauna Kea, and the Northeastern coastal plain of Maunal Loa. Rare earth element (REE) concentrations are two to six times greater in soils from the western, dry side of the island, and good statistical correlation is exhibited among the samples for pairs of individual REEs. In the organic-rich soils of the east side, correlations are poor but are markedly improved when sample weights are adjusted for weight due to organic matter and water in soil colloids. If the mean compositions of selected rock samples from the Hawaii Reference Suite are representative of the compositions of the parent materials, REEs in the soils are moderately enriched (up to two times, based on oven-dry weights). Rare earth element concentrations in the island's western soils are as much as two times greater than the mean REE values of common sedimentary rocks worldwide; however, they are well within the concentration ranges of soils of continental origin. The eastern soils tend to have less La and Ce, but similar amounts of the middle and heavy REEs.

  9. Interfacing broadband photonic qubits to on-chip cavity-protected rare-earth ensembles

    NASA Astrophysics Data System (ADS)

    Zhong, Tian; Kindem, Jonathan M.; Rochman, Jake; Faraon, Andrei

    2017-01-01

    Ensembles of solid-state optical emitters enable broadband quantum storage and transduction of photonic qubits, with applications in high-rate quantum networks for secure communications and interconnecting future quantum computers. To transfer quantum states using ensembles, rephasing techniques are used to mitigate fast decoherence resulting from inhomogeneous broadening, but these techniques generally limit the bandwidth, efficiency and active times of the quantum interface. Here, we use a dense ensemble of neodymium rare-earth ions strongly coupled to a nanophotonic resonator to demonstrate a significant cavity protection effect at the single-photon level--a technique to suppress ensemble decoherence due to inhomogeneous broadening. The protected Rabi oscillations between the cavity field and the atomic super-radiant state enable ultra-fast transfer of photonic frequency qubits to the ions (~50 GHz bandwidth) followed by retrieval with 98.7% fidelity. With the prospect of coupling to other long-lived rare-earth spin states, this technique opens the possibilities for broadband, always-ready quantum memories and fast optical-to-microwave transducers.

  10. Rare-earth oxides of manganese and cobalt rival platinum for the treatment of carbon monoxide in auto exhaust.

    PubMed

    Voorhoeve, R J; Remeika, J P; Freeland, P E; Matthias, B T

    1972-07-28

    The perovskite-like compounds RE(1-X)Pb(5)MnO(3) and RECoO(3), where RE (rare earth) is lanthanum, praseodymium, or neodymium, are active catalysts for the oxidation of carbon monoxide. Crushed single crystals of these compounds compare favorably with commercial platinum catalysts in initial activity and lifetime. Therefore, these compounds are promising substitutes for platinum in devices for the catalytic treatment of auto exhaust.

  11. Surface interactions with compartmentalized cellular phosphates explain rare earth oxide nanoparticle hazard and provide opportunities for safer design.

    PubMed

    Li, Ruibin; Ji, Zhaoxia; Chang, Chong Hyun; Dunphy, Darren R; Cai, Xiaoming; Meng, Huan; Zhang, Haiyuan; Sun, Bingbing; Wang, Xiang; Dong, Juyao; Lin, Sijie; Wang, Meiying; Liao, Yu-Pei; Brinker, C Jeffrey; Nel, Andre; Xia, Tian

    2014-02-25

    Growing international exploitation of rare earth oxides (REOs) for commercial and biological use has increased the possibility of human exposure and adverse health effects. Occupational exposure to rare earth materials in miners and polishers leads to a severe form of pneumoconiosis, while gadolinium-containing MRI contrast agents cause nephrogenic systemic fibrosis in patients with renal impairment. The mechanisms for inducing these adverse pro-fibrogenic effects are of considerable importance for the safety assessment of REO particles as well as presenting opportunities for safer design. In this study, using a well-prepared REO library, we obtained a mechanistic understanding of how REOs induce cellular and pulmonary damage by a compartmentalized intracellular biotransformation process in lysosomes that results in pro-fibrogenic growth factor production and lung fibrosis. We demonstrate that rare earth oxide ion shedding in acidifying macrophage lysosomes leads to biotic phosphate complexation that results in organelle damage due to stripping of phosphates from the surrounding lipid bilayer. This results in nanoparticle biotransformation into urchin shaped structures and setting in motion a series of events that trigger NLRP3 inflammasome activation, IL-1β release, TGF-β1 and PDGF-AA production. However, pretreatment of REO nanoparticles with phosphate in a neutral pH environment prevents biological transformation and pro-fibrogenic effects. This can be used as a safer design principle for producing rare earth nanoparticles for biological use.

  12. Highly efficient hydrophosphonylation of aldehydes and unactivated ketones catalyzed by methylene-linked pyrrolyl rare earth metal amido complexes.

    PubMed

    Zhou, Shuangliu; Wu, Zhangshuan; Rong, Jiewei; Wang, Shaowu; Yang, Gaosheng; Zhu, Xiancui; Zhang, Lijun

    2012-02-27

    A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.

  13. Not So Rare Earth? New Developments in Understanding the Origin of the Earth and Moon

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2007-01-01

    A widely accepted model for the origin of the Earth and Moon has been a somewhat specific giant impact scenario involving an impactor to proto-Earth mass ratio of 3:7, occurring 50-60 Ma after T(sub 0), when the Earth was only half accreted, with the majority of Earth's water then accreted after the main stage of growth, perhaps from comets. There have been many changes to this specific scenario, due to advances in isotopic and trace element geochemistry, more detailed, improved, and realistic giant impact and terrestrial planet accretion modeling, and consideration of terrestrial water sources other than high D/H comets. The current scenario is that the Earth accreted faster and differentiated quickly, the Moon-forming impact could have been mid to late in the accretion process, and water may have been present during accretion. These new developments have broadened the range of conditions required to make an Earth-Moon system, and suggests there may be many new fruitful avenues of research. There are also some classic and unresolved problems such as the significance of the identical O isotopic composition of the Earth and Moon, the depletion of volatiles on the lunar mantle relative to Earth's, the relative contribution of the impactor and proto-Earth to the Moon's mass, and the timing of Earth's possible atmospheric loss relative to the giant impact.

  14. [Application of ICP-MS to Detect Rare Earth Elements in Three Economic Macroalgaes in China].

    PubMed

    Zhao, Yan-fang; Shang, De-rong; Zhai, Yu-xiu; Ning, Jin-song; Ding, Hai-yan; Sheng, Xiao-feng

    2015-11-01

    In order to investigate the content and distribution of rare earth elements (REE) in main economic macroalgaes in our country, fifteen rare earth elements in three economic macroalgaes (including 30 samples of kelp, 30 samples of laver and 15 samples of Enteromorpha) were detected using ICP-MS method. Results showed that the total content of REE in different species of macroalgaes was different. The highest total content of REE was in Enteromorpha (16,012.0 ng · g⁻¹), while in kelp and laver, the total REE was similar for two macroalgaes (3887.4 and 4318.1 ng · g⁻¹ respectively). The content of fifteen rare earth elements in kelp ranged from 7.9 to 1496.4 ng · g⁻¹; in laver, it ranged from 8.2 to 1836.6 ng · g⁻¹. For Enteromorpha, the concentration of 15 rare earth elements were between 19.2 and 6014.5 ng · g⁻¹. In addition, the content and distribution of different rare earth elements in different macroalgaes was also different. For kelp, the highest content of REE was Ce (1 496.4 ng · g⁻¹), and the second was La (689.1 ng · g⁻¹). For laver, the highest was Y (1836.6 ng · g⁻¹), and the second was Ce (682.2 ng · g⁻¹). For Enteromorpha, the highest was Ce (6014.5 ng · g⁻¹), and the second was La (2902.9 ng · g⁻¹). Present results also showed that three macroalgaes accumulated the light rare earth elements much more than the high rare earth elements. The light rare earth elements occupied 90.9%, 87.3% and 91.1% for kelp, laver and Enteromorpha respectively. The result that the Enteromorpha had high content of rare earth elements could provide important support for opening new research directions for the utilization of Enteromorpha.

  15. Rare earths: atmospheric signatures for oil-fired power plants and refineries

    SciTech Connect

    Olmez, I.; Gordon, G.E.

    1985-09-06

    The concentration pattern of rare earth elements on fine airborne particles (less than 2.5 micrometers in diameter) is distorted from the crustal abundance pattern in areas influenced by emissions from oil-fired plants and refineries. For example, the ratio of lanthanum to samarium is often greater than 20 compared to a crustal ratio less than 6. The unusual pattern apparently results from the distribution of rare earths in zeolite catalysts used in refining oil. Oil industry emissions perturb the rare earth pattern even at remote locations such as the Mauna Loa Observatory in Hawaii. Rare earth ratios are probably better for long-range tracing of oil emissions than vanadium and nickel concentrations because the ratios of rare earths on fine particles are probably not influenced by deposition and other fractionating processes. Emissions from oil-fired plants can be differentiated from those of refineries on an urban scale by the much smaller amounts of vanadium in the latter. 30 references, 1 figure, 3 tables.

  16. Research of the entry of rare earth elements Eu3+ and La3+ into plant cell.

    PubMed

    Gao, Yongsheng; Zeng, Fuli; Yi, An; Ping, Shi; Jing, Lanhua

    2003-03-01

    Whether rare earth elements can enter into plant cells remains controversial. This article discusses the ultracellular structural localization of lanthanum (La(3+)) and europium (Eu(3+)) in the intact plant cells fed by rare earth elements Eu(3+) and La(3+). Eu-TTA fluorescence analysis of the plasmalemma, cytoplast, and mitochondria showed that Eu(3+) fluorescence intensities in such structures significantly increased. Eu(3+) can directly enter or be carried by the artificial ion carrier A23187 into plant cells through the calcium ion (Ca(2+)) channel and then partially resume the synthesis of amaranthin in the Amaranthus caudatus growing in the dark. Locations of rare earth elements La(3+) and Eu(3+) in all kinds of components of cytoplasmatic organelles were determined with transmission electron microscope, scanning electron microscope, and energy-dispersive X-ray microanalysis. The results of energy-dispersive X-ray microanalysis indicated that Eu(3+) and La(3+) can be absorbed into plant cells and bind to the membranes of protoplasm, chloroplast, mitochondrion, cytoplast, and karyon. These results provide experimental evidence that rare earth elements can be absorbed into plant cells, which would be the basis for interpreting physiological and biochemical effects of rare earth elements on plant cells.

  17. Computer modelling of the reduction of rare earth dopants in barium aluminate

    SciTech Connect

    Rezende, Marcos V. dos S; Valerio, Mario E.G.; Jackson, Robert A.

    2011-08-15

    Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl{sub 2}O{sub 4} lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. - Graphical abstract: The doping and subsequent reduction of a rare earth ion into the barium aluminate lattice. Highlights: > The doping of barium aluminate with rare earth ions reduced in a range of atmospheres has been modelled. > The overall solution energy for the doping process for each ion in each reducing atmosphere is calculated using two methods. > The lowest energy reduction process is predicted and compared with experimental results.

  18. The Link between Rare-Earth Peak Formation and the Astrophysical Site of the R Process

    NASA Astrophysics Data System (ADS)

    Mumpower, Matthew R.; McLaughlin, Gail C.; Surman, Rebecca; Steiner, Andrew W.

    2016-12-01

    The primary astrophysical source of the rare-earth elements is the rapid neutron capture process (r process). The rare-earth peak that is seen in the solar r-process residuals has been proposed to originate as a pile-up of nuclei during the end of the r process. We introduce a new method utilizing Monte Carlo studies of nuclear masses in the rare-earth region, that includes self-consistently adjusting β-decay rates and neutron capture rates, to find the mass surfaces necessary for the formation of the rare-earth peak. We demonstrate our method with two types of astrophysical scenario, one corresponding to conditions typical of hot winds from core-collapse supernovae and stellar-mass accretion disks, and one corresponding to conditions typical of the ejection of the material from the tidal tails of neutron star mergers. In each type of astrophysical condition, this method successfully locates a region of enhanced stability in the mass surface that is responsible for the rare-earth peak. For each scenario, we find that the change in the mass surface has qualitatively different features, thus future measurements can shed light on the type of environment in which the r process occurred.

  19. Computational search for rare-earth free hard-magnetic materials

    NASA Astrophysics Data System (ADS)

    Flores Livas, José A.; Sharma, Sangeeta; Dewhurst, John Kay; Gross, Eberhard; MagMat Team

    2015-03-01

    It is difficult to over state the importance of hard magnets for human life in modern times; they enter every walk of our life from medical equipments (NMR) to transport (trains, planes, cars, etc) to electronic appliances (for house hold use to computers). All the known hard magnets in use today contain rare-earth elements, extraction of which is expensive and environmentally harmful. Rare-earths are also instrumental in tipping the balance of world economy as most of them are mined in limited specific parts of the world. Hence it would be ideal to have similar characteristics as a hard magnet but without or at least with reduced amount of rare-earths. This is the main goal of our work: search for rare-earth-free magnets. To do so we employ a combination of density functional theory and crystal prediction methods. The quantities which define a hard magnet are magnetic anisotropy energy (MAE) and saturation magnetization (Ms), which are the quantities we maximize in search for an ideal magnet. In my talk I will present details of the computation search algorithm together with some potential newly discovered rare-earth free hard magnet. J.A.F.L. acknowledge financial support from EU's 7th Framework Marie-Curie scholarship program within the ``ExMaMa'' Project (329386).

  20. Understanding and prediction of electronic-structure-driven physical behaviors in rare-earth compounds.

    PubMed

    Paudyal, Durga; Pathak, Arjun K; Pecharsky, V K; Gschneidner, K A

    2013-10-02

    Rare-earth materials, due to their unique magnetic properties, are important for fundamental and technological applications such as advanced magnetic sensors, magnetic data storage, magnetic cooling and permanent magnets. For an understanding of the physical behaviors of these materials, first principles techniques are one of the best theoretical tools to explore the electronic structure and evaluate exchange interactions. However, first principles calculations of the crystal field splitting due to intra-site electron-electron correlations and the crystal environment in the presence of exchange splitting in rare-earth materials are rarely carried out despite the importance of these effects. Here we consider rare-earth dialuminides as model systems and show that the low temperature anomalies observed in these systems are due to the variation of both exchange and crystal field splitting leading to anomalous intra-site correlated-4f and itinerant-5d electronic states near the Fermi level. From calculations supported by experiments we uncover that HoAl2 is unique among rare-earth dialuminides, in that it undergoes a cubic to orthorhombic distortion leading to a spin reorientation. Calculations of a much more extended family of mixed rare-earth dialuminides reveal an additional degree of complexity: the effective quadrupolar moment of the lanthanides changes sign as a function of lanthanide concentration, leading to a change in the sign of the anisotropy constant. At this point the quadrupolar interactions are effectively reduced to zero, giving rise to lattice instability and leading to new phenomena. This study shows a clear picture that accurate evaluation of the exchange, crystal field splitting and shape of the charge densities allows one to understand, predict and control the physical behaviors of rare-earth materials.

  1. Preparation and fluorescence properties of crystalline gel rare earth phosphates.

    PubMed

    Onoda, Hiroaki; Funamoto, Takehiro

    2015-03-01

    An aqueous solution of sodium dihydrogen phosphate was mixed with a aqueous solution of lanthanum nitrate and stirred for 24 h, and the pH was adjusted to 11 using ammonia. The obtained phosphates were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry-differential thermal analysis, and scanning electron microscopy. The lanthanum phosphate gel was obtained with a large amount of water. The fluorescence of the gels was investigated by substituting a part of the lanthanum cations with cerium, terbium, and europium cations. UV-vis reflectance and fluorescence spectra of these substituted materials were obtained and analyzed. Rrare-earth phosphate gels with large amounts of water exhibited bluish purple, green, and red fluorescence when cation ratios of La/Ce = 70/30, La/Ce/Tb = 55/30/15, and La/Eu = 95/5 were used, respectively.

  2. Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

    PubMed

    Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

    2017-02-01

    Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H2SO4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO2eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage.

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

    PubMed

    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.

  4. Rare earths, other trace elements and iron in Luna 20 samples.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Blanchard, D. P.; Jacobs, J. W.; Haskin, L.; Haskin, A.

    1973-01-01

    The results of the analysis by neutron activation of six samples from the Luna 20 mission and one sample of less than 1 mm fines from Apollo 16 are reported. The concentrations of the rare-earth elements (REE) in the samples of fines from Luna 20 and Apollo 16 are less than those found for corresponding materials from the mare areas but a negative Eu anomaly is still present. The concentrations of the REE in fines from Luna 20 are only about two-thirds as great as in the sample of Apollo 16 fines, but the concentration of Co, Sc and Cr are greater by factors ranging from 1.5 to 2.3.

  5. Naturally occurring radionuclides and rare earth elements in weathered Japanese soil samples

    NASA Astrophysics Data System (ADS)

    Sahoo, Sarata; Hosoda, Masahiro; Prasad, Ganesh; Takahashi, Hiroyuki; Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Uchida, Shigeo

    2013-08-01

    The activity concentrations of 226Ra and 228Ac in weathered Japanese soils from two selected prefectures have been measured using a γ-ray spectroscopy system with high purity germanium detector. The uranium, thorium, and rare earth elements (REEs) concentrations were determined from the same soil samples using inductively coupled plasma mass spectrometry (ICP-MS). For example, granitic rocks contain higher amounts of U, Th, and light REEs compared to other igneous rocks such as basalt and andesites. Therefore, it is necessary to understand the interaction between REEs and nature of soils since soils are complex heterogeneous mixture of organic and inorganic solids, water, and gases. In this paper, we will discuss about distribution pattern of 238U and 232Th along with REEs in soil samples of weathered acid rock (granite) collected from two prefectures of Japan: Hiroshima and Miyagi.

  6. Defect association mediated ionic conductivity of rare earth doped nanoceria: Dependency on ionic radius

    NASA Astrophysics Data System (ADS)

    Anirban, Sk.; Sinha, A.; Bandyopadhyay, S.; Dutta, A.

    2016-05-01

    Rare earth doped nanoceria Ce0.9RE0.1O1.95 (RE = Pr, Nd, Eu and Gd) were prepared through citrate auto-ignition method. The single phase cubic fluorite structure with space group Fm3 ¯m of the compositions were confirmed from Rietveld analysis of XRD data. The particle size of the compositions were in the range 49.77 nm to 66.20 nm. An ionic radius dependent lattice parameter variation was found. The DC conductivity of each composition was evaluated using Random Barrier Model. The conductivity decreased and activation energy increased with increasing ionic radius from Gd to Pr doping due to the size mismatch with host ions and formation of stable defect associate. The formation of different defect associates and their correlation with ionic conductivity has been discussed.

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

    PubMed

    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.

  8. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    NASA Astrophysics Data System (ADS)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  9. Effects of rare earth elements and REE-binding proteins on physiological responses in plants.

    PubMed

    Liu, Dongwu; Wang, Xue; Chen, Zhiwei

    2012-02-01

    Rare earth elements (REEs), which include 17 elements in the periodic table, share chemical properties related to a similar external electronic configuration. REEs enriched fertilizers have been used in China since the 1980s. REEs could enter the cell and cell organelles, influence plant growth, and mainly be bound with the biological macromolecules. REE-binding proteins have been found in some plants. In addition, the chlorophyll activities and photosynthetic rate can be regulated by REEs. REEs could promote the protective function of cell membrane and enhance the plant resistance capability to stress produced by environmental factors, and affect the plant physiological mechanism by regulating the Ca²⁺ level in the plant cells. The focus of present review is to describe how REEs and REE-binding proteins participate in the physiological responses in plants.

  10. 75 FR 25293 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Rare Earth...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-07

    ... Earth Industry and Technology Association Notice is hereby given that, on March 22, 2010, pursuant to.... (``the Act''), the Rare Earth Technology Consortium (``RETC'') has filed written notifications... to the venture are: Rare Earth Industry and Tecimology Association, Greenwood Village, CO;...

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

    PubMed

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

    2014-04-01

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

  12. Heteroscorpionate rare-earth initiators for the controlled ring-opening polymerization of cyclic esters.

    PubMed

    Otero, Antonio; Lara-Sánchez, Agustín; Fernández-Baeza, Juan; Alonso-Moreno, Carlos; Márquez-Segovia, Isabel; Sánchez-Barba, Luis F; Castro-Osma, José A; Rodríguez, Ana M

    2011-05-07

    A series of neutral rare-earth metal amides containing different achiral and chiral heteroscorpionate ligands was synthesized and characterized and these compounds were employed in the polymerization of cyclic esters. Thus, treatment of [Ln{N(SiHMe(2))(2)}(3)(thf)(2)] (Ln = Nd, Sm) with acetamide or thioacetamide heteroscorpionate ligands for 2 h at 0 °C afforded the α-agostic silylamido dimeric rare-earth compounds [Ln{N(SiHMe(2))(2)}(NNE)](2) (Ln = Nd and Sm; NNE = heteroscorpionate ligands, E = O, S) (1-8), some as enantiopure complexes. Complexes 1-8 contain dianionic heteroscorpionate pseudoallyl ligands resulting from C-H activation of the bridging methine group of the bis(pyrazol-1-yl)methane moiety and subsequent coordination to the metal center. However, when the reaction was carried out for 1 h at lower temperature new bis(silylamido) dimeric lanthanide compounds [Ln{N(SiHMe(2))(2)}(2)(NNE)](2) (Ln = Nd and Sm; E = O) (9 and 10) were obtained. The structures of the complexes were determined by spectroscopic methods and the X-ray crystal structures of 1, and 4 were also established. Neodymium complexes are active initiators for the ring-opening polymerization (ROP) of lactide (LA) and lactones, giving rise to medium-high molar mass polymers under mild conditions and with narrow polydispersities. These complexes were well suited for achieving well-controlled polymerization through an insertion-coordination mechanism. Achiral and racemic complexes did not affect stereocontrol in the polymerizarion of rac-LA but the enantiomerically pure complex 1 was found to exhibit a homosteric preference for one of the two enantiomers of rac-LA at low conversions.

  13. Shifted homologous relationships between the transplutonium and early rare-earth metals

    SciTech Connect

    Ward, J.W.

    1984-01-01

    The physico-chemical properties of the late actinide metals americium through einsteinium are compared with their rare-earth counterparts. Localization of the 5f electrons beginning at americium signals the appearance of true rare-earth-like properties, but the homologous relationship is shifted to place americium below praseodymium, einsteinium then below europium. The comparison of crystal structure, phase transitions, vapor pressures and heats of vaporization reveals remarkable similarities, especially for Sm-Cf and Eu-Es, where the stability of the divalent metal becomes established and divalent chemistry then follows. There is of course a major perturbation at the half-filled shell at curium, and it may be argued that americium is the anomaly in the so-called second rare-earth series. However, the response of americium, berkelium and californium under pressure reveals the true perturbation to be a thermodynamic one, occurring at curium.

  14. Crystal-field interaction and oxygen stoichiometry effects in strontium-doped rare-earth cobaltates

    NASA Astrophysics Data System (ADS)

    Furrer, A.; Podlesnyak, A.; Frontzek, M.; Sashin, I.; Embs, J. P.; Mitberg, E.; Pomjakushina, E.

    2014-08-01

    Inelastic neutron scattering was employed to study the crystal-field interaction in the strontium-doped rare-earth compounds RxSr1-xCoO3-z (R=Pr, Nd, Ho, and Er). Particular emphasis is laid on the effect of oxygen deficiencies that naturally occur in the synthesis of these compounds. The observed energy spectra are found to be the result of a superposition of crystal fields with different nearest-neighbor oxygen coordination at the R sites. The experimental data are interpreted in terms of crystal-field parameters, which behave in a consistent manner through the rare-earth series, thereby allowing a reliable extrapolation for rare-earth ions not considered in the present work.

  15. Mössbauer study of the effect of rare earth substitution into montmorillonite

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Singh, L. H.; Garg, V. K.; de Oliveira, A. C.; Kovács, E. M.; Molnár, Á. M.; Homonnay, Z.; Kónya, P.; Nagy, N. M.; Kónya, J.

    2016-12-01

    Novel montmorillonites were prepared by the exchange of the interlayer cations with a series of rare earth cations (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Er) and characterized by XRD, XRF, SEM, chemical analysis and 57Fe Mössbauer spectroscopy. An unexpected magnetically split component, assigned to iron being in the interlayer space, was observed in the Mössbauer spectra at 78K in some rare earth cation exchanged montmorillonite. This paper is the initial report about this observation. The transition of iron from the octahedral site to the interlayer and possible incorporation of rare earths in sites different from those which are in the interlayer space was concluded.

  16. Electronic, structural and transport properties of (almost) rare-earth-like actinide hydrides

    SciTech Connect

    Ward, J.W.; Cort, B.; Goldstone, J.A.; Lawson, A.C.; Cox, L.E. ); Haire, R.G. )

    1990-01-01

    By the virtue of broad-band, hybridized 5f-electron behavior, the hydride systems for Pa and U exhibit unique properties and structures, the actinide metal atoms existing in different states. A sudden change at Np to more rare-earth-like behavior implies a major change in electronic structure. There are both many parallels but also enigmas for the Np + H and Pu + H systems. Electrical resistivities are large and complex with temperature. Low-temperature structural transitions as studied by neutron diffraction help elucidate some of these effects. Phonon spectra are quite rare-earth-like, and XPS data imply a metal atom with mostly d-screened core levels. Then it is at americium, where fully localized and corelike 5f electrons are found, that we look finally for true rare-earth-like behavior, which should include a large drop in electrical resistivity. 33 refs., 7 figs., 1 tab.

  17. Rare earth-doped materials with enhanced thermoelectric figure of merit

    DOEpatents

    Venkatasubramanian, Rama; Cook, Bruce Allen; Levin, Evgenii M.; Harringa, Joel Lee

    2016-09-06

    A thermoelectric material and a thermoelectric converter using this material. The thermoelectric material has a first component including a semiconductor material and a second component including a rare earth material included in the first component to thereby increase a figure of merit of a composite of the semiconductor material and the rare earth material relative to a figure of merit of the semiconductor material. The thermoelectric converter has a p-type thermoelectric material and a n-type thermoelectric material. At least one of the p-type thermoelectric material and the n-type thermoelectric material includes a rare earth material in at least one of the p-type thermoelectric material or the n-type thermoelectric material.

  18. Method of forming magnetostrictive rods from rare earth-iron alloys

    DOEpatents

    McMasters, O. Dale

    1986-09-02

    Rods of magnetrostructive alloys of iron with rare earth elements are formed by flowing a body of rare earth-iron alloy in a crucible enclosed in a chamber maintained under an inert gas atmosphere, forcing such molten rare-earth-iron alloy into a hollow mold tube of refractory material positioned with its lower end portion within the molten body by means of a pressure differential between the chamber and mold tube and maintaining a portion of the molten alloy in the crucible extending to a level above the lower end of the mold tube so that solid particles of higher melting impurities present in the alloy collect at the surface of the molten body and remain within the crucible as the rod is formed in the mold tube.

  19. Method of forming magnetostrictive rods from rare earth-iron alloys

    DOEpatents

    McMasters, O.D.

    1986-09-02

    Rods of magnetostrictive alloys of iron with rare earth elements are formed by flowing a body of rare earth-iron alloy in a crucible enclosed in a chamber maintained under an inert gas atmosphere, forcing such molten rare-earth-iron alloy into a hollow mold tube of refractory material positioned with its lower end portion within the molten body by means of a pressure differential between the chamber and mold tube and maintaining a portion of the molten alloy in the crucible extending to a level above the lower end of the mold tube so that solid particles of higher melting impurities present in the alloy collect at the surface of the molten body and remain within the crucible as the rod is formed in the mold tube. 5 figs.

  20. Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

    DOEpatents

    Duncan, Paul G.

    2002-01-01

    Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.