Science.gov

Sample records for 4f rare earth

  1. The screening of 4f moments and delocalization in the compressed light rare earths

    SciTech Connect

    McMahan, A K; Scalettar, R T; Jarrell, M

    2009-08-19

    Spin and charge susceptibilities and the 4f{sup n}, 4f{sup n{+-}1} configuration weights are calculated for compressed Ce (n=1), Pr (n=2), and Nd (n=3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f{sup n} configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f{sup n-1} configurations, which it is argued are better measures of delocalization than the 4f{sup n+1} weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed {alpha}-{gamma} collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.

  2. Quantitative moment study and coupling of 4 f rare earth and 3 d metal by transmitted electrons

    NASA Astrophysics Data System (ADS)

    Fu, X.; Warot-Fonrose, B.; Arras, R.; Dumesnil, K.; Serin, V.

    2016-10-01

    We report a simultaneous investigation of 3 d and 4 f magnetic moments by exploring the Fe -L2 ,3 and Dy -M4 ,5 electron energy-loss edges of a DyF e2/YF e2 superlattice using the energy-loss magnetic chiral dichroism (EMCD) technique. Specific EMCD sum rules for M4 ,5 edges were established and carefully applied to the dichroic signal at Dy -M4 ,5 edges, giving an orbital to the effective spin moment ratio of 5.1 ±1.8 . With dynamic diffraction effects considered, the opposite signs of Fe -L3 and Dy -M5 dichroic peaks unambiguously indicate the antiparallel alignment of net Fe 3 d and Dy 4 f moments. The EMCD technique is shown to be an effective tool to locally characterize the 4 f moment of rare earth elements and study 3 d -4 f moment coupling.

  3. NMR study of valence fluctuating state in rare-earth based materials with multi-4f electrons

    NASA Astrophysics Data System (ADS)

    Mito, Takeshi

    2013-02-01

    Intermetallic compounds containing rare-earth elements have been a focus of interest due to their variety of intriguing phenomena, such as heavy fermion, valence fluctuation, magnetism, and superconductivity. Nuclear magnetic resonance (NMR) has played an important role in uncovering electronic states in those rare-earth based materials at the microscopic level. Among them, while cerium based materials have been intensively studied, there are so far a little NMR investigations on materials containing other rare-earth elements, such as samarium, europium, ytterbium, and so on, in spite of their attractive properties. We have recently concentrated on investigating the valence fluctuating states in the compounds with multi-4f electron configurations by NMR. Intermediate valence compound SmB6 undergoes an insulator-metal transition at the critical pressure 6-10 GPa [1,2], accompanied by the occurrence of a long-range magnetic order. In order to investigate intimate relationships between the insulating gap-formation, valence change, and magnetization as a function of pressure, we have successfully performed 11B-NMR up to ˜6 GPa. In this talk, we shall also present the result on EuPtP which shows two valence transitions at 235 K and 190 K [3].

  4. Rare Earth 4f Hybridization with the GaN Valence Band

    DTIC Science & Technology

    2012-01-01

    DOS of Ga17GdN18. and Auger-like electrons emitted in a super Coster– Kronig process [52] 4d104fN + hν → [4d94fN+1]∗ → 4d104fN−1 + e−, (2) where...similar, albeit not identical, response for GaN:Er compared to GaN:Gd at the photon energy characteristic for the Er 4d → 4f super Coster– Kronig resonance

  5. High-precision, systematic study of hyperfine structure in the 4f/sup N/6s/sup 2/ configuration of the neutral rare earths

    SciTech Connect

    Childs, W.J.; Goodman, L.S.; Pfeufer, V.

    1983-01-01

    Although the hyperfine structure (hfs) of many-electron atoms has been studied intensively in recent years, it is still difficult to distinguish between the competing effects of relativity and configuration interaction. The 4f/sup N/6s/sup 2/ configuration of the neutral rare earths is of particular interest because (a) the low-lying terms are relatively free of configuration interaction, and (b) trends can be examined systematically as one proceeds through the long 4f-shell. The procedure is to deduce, from the measured hfs constants of low levels, the underlying hyperfine radial integrals for comparison with ab initio predictions. Since some of these integrals are extremely sensitive to any configuration interaction and others are not, it is possible to determine both the extent and type of configuration interaction present in some cases. Prior to the start of the present research no precise hfs information existed for the entire second half of the 4f shell of the rare earths. The present measurements were designed both to provide such data and to make possible a systematic study of the hfs throughout the 4f shell. The atomic-beam, laser-rf, double-resonance method was used for the measurements. With this technique, the occurrence of a radiofrequency transition between atomic hfs levels is detected by noting an increase in the laser-induced fluorescence.

  6. Tuning the Origin of Magnetic Relaxation by Substituting the 3d or Rare-Earth Ions into Three Isostructural Cyano-Bridged 3d-4f Heterodinuclear Compounds.

    PubMed

    Zhang, Yan; Guo, Zhen; Xie, Shuang; Li, Hui-Li; Zhu, Wen-Hua; Liu, Li; Dong, Xun-Qing; He, Wei-Xun; Ren, Jin-Chao; Liu, Ling-Zhi; Powell, Annie K

    2015-11-02

    Three isostructural cyano-bridged 3d-4f compounds, [YFe(CN)6(hep)2(H2O)4] (1), [DyFe(CN)6(hep)2(H2O)4] (2), and [DyCo(CN)6(hep)2(H2O)4] (3), were successfully assembled by site-targeted substitution of the 3d or rare-earth ions. All compounds have been structurally characterized to display slightly distorted pentagonal-bipyramidal local coordination geometry around the rare-earth ions. Magnetic analyses revealed negligible magnetic coupling in compound 1, antiferromagnetic intradimer interaction in 2, and weak ferromagnetic coupling through dipolar-dipolar interaction in 3. Under an applied direct-current (dc) field, 1 (Hdc = 2.5 kOe, τ0 = 1.3 × 10(-7) s, and Ueff/kB = 23 K) and 3 (Hdc = 2.0 kOe, τ0 = 7.1 × 10(-11) s, and Ueff/kB = 63 K) respectively indicated magnetic relaxation behavior based on a single [Fe(III)]LS ion and a Dy(III) ion; nevertheless, 2 (Hdc = 2.0 kOe, τ0 = 9.7 × 10(-8) s, and Ueff/kB = 23 K) appeared to be a single-molecule magnet based on a cyano-bridged DyFe dimer. Compound 1, which can be regarded as a single-ion magnet of the [Fe(III)]LS ion linked to a diamagnetic Y(III) ion in a cyano-bridged heterodimer, represents one of the rarely investigated examples based on a single Fe(III) ion explored in magnetic relaxation behavior. It demonstrated that the introduction of intradimer magnetic interaction of 2 through a cyano bridge between Dy(III) and [Fe(III)]LS ions negatively affects the energy barrier and χ″(T) peak temperature compared to 3.

  7. Electronic structure of rare-earth nitrides using the LSDA+U approach: Importance of allowing 4f orbitals to break the cubic crystal symmetry

    NASA Astrophysics Data System (ADS)

    Larson, P.; Lambrecht, Walter R. L.; Chantis, Athanasios; van Schilfgaarde, Mark

    2007-01-01

    Electronic structure calculations were performed for the rare-earth (RE) nitrides in the rocksalt structure using density functional theory calculations within the LSDA+U approach (local spin density approximation with Hubbard- U corrections). The LSDA+U method is implemented in the full-potential linearized muffin-tin orbital method and applied to the 4f as well as 5d states. Parameters U and J were determined from atomic calculations complemented with experimental photoemission and inverse photoemission data and optical absorption data for Gd pnictides. The solution for the density matrix of f electrons is not unique and thus several configurations need to be investigated to determine the lowest energy state. A trivalent solution is found to have the lowest energy in all cases except CeN , which was found to be tetravalent. Hund’s second rule requires maximizing the orbital momentum component Lz , which breaks the cubic symmetry and lowers the total energy. We find Hund’s second rule to be obeyed in all cases except EuN and YbN , where a cubic symmetry solution has lower energy. In these cases, the divalent solution is also in competition with the trivalent solution. The symmetry breaking in most cases lowers the total energy and in some cases, those with two electrons or holes away from a closed or half-filled shell, is essential to remove f states from the Fermi level. The spin magnetic moments are nearly integer, defined by the number of filled 4f states. The orbital magnetic moment is of comparable magnitude to the spin moment. Hund’s third rule, according to which the orbital and spin moment are opposite to each other in the first half of the series but parallel to each other in the second half, is also found to be obeyed. Interestingly, this leads to zero net magnetic moment for SmN .Apart from the few cases where f states remain close to the Fermi level, the band structure is borderline semiconductor to semimetallic in most cases, a RE 5d conduction

  8. 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.

  9. Oxo-functionalization and reduction of the uranyl ion through lanthanide-element bond homolysis: synthetic, structural, and bonding analysis of a series of singly reduced uranyl-rare earth 5f1-4f(n) complexes.

    PubMed

    Arnold, Polly L; Hollis, Emmalina; Nichol, Gary S; Love, Jason B; Griveau, Jean-Christophe; Caciuffo, Roberto; Magnani, Nicola; Maron, Laurent; Castro, Ludovic; Yahia, Ahmed; Odoh, Samuel O; Schreckenbach, Georg

    2013-03-13

    The heterobimetallic complexes [{UO2Ln(py)2(L)}2], combining a singly reduced uranyl cation and a rare-earth trication in a binucleating polypyrrole Schiff-base macrocycle (Pacman) and bridged through a uranyl oxo-group, have been prepared for Ln = Sc, Y, Ce, Sm, Eu, Gd, Dy, Er, Yb, and Lu. These compounds are formed by the single-electron reduction of the Pacman uranyl complex [UO2(py)(H2L)] by the rare-earth complexes Ln(III)(A)3 (A = N(SiMe3)2, OC6H3Bu(t)2-2,6) via homolysis of a Ln-A bond. The complexes are dimeric through mutual uranyl exo-oxo coordination but can be cleaved to form the trimetallic, monouranyl "ate" complexes [(py)3LiOUO(μ-X)Ln(py)(L)] by the addition of lithium halides. X-ray crystallographic structural characterization of many examples reveals very similar features for monomeric and dimeric series, the dimers containing an asymmetric U2O2 diamond core with shorter uranyl U═O distances than in the monomeric complexes. The synthesis by Ln(III)-A homolysis allows [5f(1)-4f(n)]2 and Li[5f(1)-4f(n)] complexes with oxo-bridged metal cations to be made for all possible 4f(n) configurations. Variable-temperature SQUID magnetometry and IR, NIR, and EPR spectroscopies on the complexes are utilized to provide a basis for the better understanding of the electronic structure of f-block complexes and their f-electron exchange interactions. Furthermore, the structures, calculated by restricted-core or all-electron methods, are compared along with the proposed mechanism of formation of the complexes. A strong antiferromagnetic coupling between the metal centers, mediated by the oxo groups, exists in the U(V)Sm(III) monomer, whereas the dimeric U(V)Dy(III) complex was found to show magnetic bistability at 3 K, a property required for the development of single-molecule magnets.

  10. 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.

  11. 5 d-4 f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

    NASA Astrophysics Data System (ADS)

    Radzhabov, E. A.; Prosekina, E. A.

    2011-09-01

    The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF2, SrF2, BaF2) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5 d state to different 4 f levels of rare earth ions.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  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. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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 ...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

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

    PubMed

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

    2014-10-15

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

  17. Visible to infrared low temperature photoluminescence of rare earth doped bismuth germanate crystals.

    PubMed

    Canimoglu, A; Ayvacikli, M; Karabulut, Y; Karali, T; Can, N

    2016-05-01

    In this paper, the influence of a series of rare earth (Eu, Tm, Nd) and Cr ion doping on the optical properties of BGO was investigated by means of photoluminescence (PL) from visible to IR region in the 10-300K temperature range using different types of detectors, namely, photomultiplier tube (PMT), InGaAs (IGA), and Si. Several samples were investigated having dopants concentrations of 0.3wt%Nd, 0.4wt%Tm, 0.06wt% Cr and 3ppm Eu. The PL spectra of the samples showed different luminescence behaviour which is assigned to the 4f intra shell transition from rare earth ions. The temperature dependence of the PL from rare earth doped BGO crystals is also examined.

  18. Impurity trapped exciton states related to rare earth ions in crystals under high hydrostatic pressure

    SciTech Connect

    Grinberg, M. Mahlik, S.

    2013-01-15

    Emission related to rare earth ions in solids takes place usually due to 4f{sup n} {yields} 4f{sup n} and 4f{sup n-1}5d{sup 1} {yields} 4f{sup n} internal transitions. In the case of band to band excitation the effective energy transfer from the host to optically active impurity is required. Among other processes one of the possibilities is capturing of the electron at excited state and hole at the ground state of impurity. Localization of electron or hole at the dopand site creates a long range Coulomb potential that attracts the second carrier which then occupies the localized Rydberg-like states. Such a system can be considered as impurity trapped exciton. Usually impurity trapped exciton is a short living phenomenon which decays non-radiatively leaving the impurity ion in the excited state. However, in several compounds doped with Eu{sup 2+} the impurity trapped exciton states become stable and contribute to the radiative processes though anomalous luminescence that appears apart of the 4f{sup 7} {yields} 4f{sup 7} and 4f{sup 7}5d{sup 1} {yields} 5f{sup 7} emission. In this contribution pressure effect on energies of the 4f{sup n-1}5d{sup 1}{yields}5f{sup n} transitions in Ln doped oxides and fluorides as well as influence of pressure on the energy of impurity trapped exciton states is discussed. The latest results on high pressure investigations of luminescence related to Pr{sup 3+}, and Eu{sup 2+} in different lattices are reviewed.

  19. 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).

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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

  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. 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.

  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. 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.

  1. 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.

  2. 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

  3. Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling

    PubMed Central

    Coffey, David; Diez-Ferrer, José Luis; Serrate, David; Ciria, Miguel; Fuente, César de la; Arnaudas, José Ignacio

    2015-01-01

    High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths. PMID:26333417

  4. Resonant Enhancement of Charge Density Wave Diffraction in the Rare-Earth Tri-Tellurides

    SciTech Connect

    Lee, W.S.; Sorini, A.P.; Yi, M.; Chuang, Y.D.; Moritz, B.; Yang, W.L.; Chu, J.-H.; Kuo, H.H.; Gonzalez, A.G.Cruz; Fisher, I.R.; Hussain, Z.; Devereau, T.P.; Shen, Z.X.

    2012-05-15

    We performed resonant soft X-ray diffraction on known charge density wave (CDW) compounds, rare earth tri-tellurides. Near the M{sub 5} (3d - 4f) absorption edge of rare earth ions, an intense diffraction peak is detected at a wavevector identical to that of CDW state hosted on Te{sub 2} planes, indicating a CDW-induced modulation on the rare earth ions. Surprisingly, the temperature dependence of the diffraction peak intensity demonstrates an exponential increase at low temperatures, vastly different than that of the CDW order parameter. Assuming 4f multiplet splitting due to the CDW states, we present a model to calculate X-ray absorption spectrum and resonant profile of the diffraction peak, agreeing well with experimental observations. Our results demonstrate a situation where the temperature dependence of resonant X-ray diffraction peak intensity is not directly related to the intrinsic behavior of the order parameter associated with the electronic order, but is dominated by the thermal occupancy of the valence states.

  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. 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.

  11. 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.

  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. Rare earth ions as heterogeneous photocatalysts for the decomposition of dinitrogen monoxide (N{sub 2}O)

    SciTech Connect

    1995-11-01

    Optical and spectroscopic properties of rare earth ions have been extensively investigated. Generally, the photoexcited state of the rare earth cations is generated by the absorption of light, corresonding to the transition of the electrons situated in the inner 4f orbital to the 5d orbitals (4f-5d transition) or to other 4f orbitals (f-f transition). The ions in the excited state have the capability of transfering their excited energy to other molecules in the gas phase or in the adsorbed state. Such energy transfer processes can lead to the rare earth cations acting as photocatalysts. However, little has been reported about their photocatalysts, except for the photochemical evolution of hydrogen and the photochemical conversion of {alpha}-methylstyrene to 2,3-dimethyl-2,3-diphenylbutane and 3,4-dimethyl-3,4-diphenylpentanol using europium chlorides in a homogeneous liquid phase. In the present note, the authors report evidence for the heterogeneous photocatalysis of rare earth cations in the decomposition of dinitrogen monoxide (N{sub 2}O) into nitrogen and oxygen molecules. The authors found that praseodymium (Pr) ion-exchanged mordenite and alumina- and silica-alumina-supported Pr are effective photocatalysts for the decomposition of N{sub 2}O. The stoichiometric photodecomposition of N{sub 2}O proceeded only on the Pr-mordenite. 17 refs., 2 figs., 1 tab.

  14. 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.

  15. 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.

  16. 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)

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

    PubMed

    Nishiura, Masayoshi; Guo, Fang; Hou, Zhaomin

    2015-08-18

    The search for new catalysts for more efficient, selective chemical transformations and for the synthesis of new functional materials has been a long-standing research subject in both academia and industry. To develop new generations of catalysts that are superior or complementary to the existing ones, exploring the potential of untapped elements is an important strategy. Rare-earth elements, including scandium, yttrium, and the lanthanides (La-Lu), constitute one important frontier in the periodic table. Rare-earth elements possess unique chemical and physical properties that are different from those of main-group and late-transition metals. The development of rare-earth-based catalysts by taking the advantage of these unique properties is of great interest and importance. The most stable oxidation state of rare-earth metals is 3+, which is difficult to change under many reaction conditions. The oxidative addition and reductive elimination processes often observed in catalytic cycles involving late transition metals are generally difficult in the case of rare-earth complexes. The 18-electron rule that is applicable to late-transition-metal complexes does not fit rare-earth complexes, whose structures are mainly governed by the sterics (rather than the electron numbers) of the ligands. In the lanthanide series (La-Lu), the ionic radius gradually decreases with increasing atomic number because of the influence of the 4f electrons, which show poor shielding of nuclear charge. Rare-earth metal ions generally show strong Lewis acidity and oxophilicity. Rare-earth metal alkyl and hydride species are highly reactive, showing both nucleophilicity and basicity. The combination of these features, such as the strong nucleophilicity and moderate basicity of the alkyl and hydride species and the high stability, strong Lewis acidity, and unsaturated C-C bond affinity of the 3+ metal ions, can make rare-earth metals unique candidates for the formation of excellent single

  18. 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.

  19. White emission phosphors based on Dy3+-doped into anhydrous rare-earth benzenetricarboxylate complexes

    NASA Astrophysics Data System (ADS)

    Silva, Ivan G. N.; Kai, Jiang; Felinto, Maria C. F. C.; Brito, Hermi F.

    2013-03-01

    White light emitting rare earth anhydrous complexes RE(TMA):Dy3+ (RE3+ = Y3+ and Lu3+) containing the trimesic acid ligands (TMA) were synthesized and characterized by elemental analysis, X-ray diffraction patterns, thermogravimetric analysis and infrared spectroscopy. The crystallinity and thermostability of these luminescent materials were determined. Since the first excited triplet state (T1: 24,000 cm-1) of TMA ligand is located at higher energy than the main emitting 4F9/2 level (21,000 cm-1) of the Dy3+ ion, TMA can act as efficient luminescent sensitizer in the intramolecular energy transfer of RE(TMA):Dy3+ material. The near-white emission colour originated from the intraconfigurational transitions of Dy3+ ion 4F9/2→6HJ is discussed.

  20. Role of atomic multiplets in the electronic structure of rare-earth semiconductors and semimetals.

    PubMed

    Pourovskii, Leonid V; Delaney, Kris T; Van de Walle, Chris G; Spaldin, Nicola A; Georges, Antoine

    2009-03-06

    We present a study of the effects of strong correlations in rare-earth pnictides, in which localized 4f states simultaneously retain atomiclike character and strongly influence the free-electron-like valence electron states. Using erbium arsenide as our example, we use a modern implementation of dynamical mean-field theory to obtain the atomic multiplet structure of the Er3+ 4f shell, as well as its unusually strong coupling to the electronic Fermi surfaces; these types of behavior are not correctly described within conventional electronic-structure methods. We are then able to explain the long-standing theoretical question of the quasisaturation of magnetization in an applied magnetic field, and to obtain the first quantitative agreement with experimental Shubnikov-de Haas frequencies of the Fermi-surface sheets.

  1. 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

  2. [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.

  3. 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.

  4. X-ray photoelectron spectra and electronic structure of rare-earth orthovanadates

    NASA Astrophysics Data System (ADS)

    Ryzhkov, M. V.; Kostikov, S. P.; Ivanov, I. K.; Gubanov, V. A.

    1981-08-01

    Photoelectron spectra of 4 d and valence states in RVO 4 ( R = Y, Nd, Eu, Gd, Tb, Dy, Yb) have been investigated. The experimental spectra are interpreted using the results of the Xα discrete variational method calculations for orthovanadates. Transformations of electronic structure and covalency in the RVO 4 series are discussed. It is shown that lanthanide 4 f orbitals significantly mix with the O 2 pAO's and hybridize with the rare-earths 5 pAO's. The 5 p levels spin-orbital splitting in orthovanadates has been evaluated.

  5. 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

  6. Nanophotonic coherent light–matter interfaces based on rare-earth-doped crystals

    PubMed Central

    Zhong, Tian; Kindem, Jonathan M.; Miyazono, Evan; Faraon, Andrei

    2015-01-01

    Quantum light–matter interfaces connecting stationary qubits to photons will enable optical networks for quantum communications, precise global time keeping, photon switching and studies of fundamental physics. Rare-earth-ion-doped crystals are state-of-the-art materials for optical quantum memories and quantum transducers between optical photons, microwave photons and spin waves. Here we demonstrate coupling of an ensemble of neodymium rare-earth-ions to photonic nanocavities fabricated in the yttrium orthosilicate host crystal. Cavity quantum electrodynamics effects including Purcell enhancement (F=42) and dipole-induced transparency are observed on the highly coherent 4I9/2–4F3/2 optical transition. Fluctuations in the cavity transmission due to statistical fine structure of the atomic density are measured, indicating operation at the quantum level. Coherent optical control of cavity-coupled rare-earth ions is performed via photon echoes. Long optical coherence times (T2∼100 μs) and small inhomogeneous broadening are measured for the cavity-coupled rare-earth ions, thus demonstrating their potential for on-chip scalable quantum light–matter interfaces. PMID:26364586

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Rare-earth antisites in lutetium aluminum garnets: Influence on lattice parameter and Ce3+ multicenter structure

    NASA Astrophysics Data System (ADS)

    Przybylińska, H.; Wittlin, A.; Ma, Chong-Geng; Brik, M. G.; Kamińska, A.; Sybilski, P.; Zorenko, Yu.; Nikl, M.; Gorbenko, V.; Fedorov, A.; Kučera, M.; Suchocki, A.

    2014-07-01

    Low temperature, infrared transmission spectra of lutetium aluminum garnet (LuAG) bulk crystals and epitaxial layers doped with Ce are presented. In the region of intra-configurational 4f-4f transitions the spectra of the bulk LuAG crystal exhibit the signatures of several different Ce3+ related centers. Apart from the dominant center, associated with Ce substituting lutetium, at least six other centers are found, some of them attributed to so-called antisite locations of rare-earth ions in the garnet host, i.e., ions in the Al positions. X-ray diffraction data prove lattice expansion of bulk LuAG crystals due presence of rare-earth antisites.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. Coulomb correlation effects in the quasiparticle band structure of ferromagnetic rare-earth insulators

    NASA Astrophysics Data System (ADS)

    Nolting, W.; Borgiel, W.; Borstel, G.

    1988-05-01

    We present a method for calculating the temperature dependence of the electronic quasiparticle density of states (QDOS) of a ferromagnetic rare-earth insulator like EuO. Special attention is devoted to how the ``localized'' ferromagnetism manifests itself in x-ray photoemission and bremsstrahlung isochromat spectra. Our study includes the first six conduction bands of EuO (the first five are Eu 5d like, the sixth is mainly of Eu 6s character) as well as the rather flat 4f levels. The starting point is an extended d-f exchange model, the main parts of which are an exchange interaction between 4f moments and conduction electrons, a Coulomb repulsion between highly correlated 4f electrons, and a hybridization of 4f with conduction-band states. We use an exact T=0 relationship between spin-up quasiparticle energies and one-electron Bloch energies ɛm(k) for an optimal determination of the latter by performing a self-consistent, spin-polarized band-structure calculation based on density-functional theory. For finite temperatures the model is approximately solved by a many-body procedure. The QDOS exhibits a striking temperature dependence mainly due to the d-f exchange. Two 4f-like peaks appear in the spin-polarized QDOS, the low-energy one being occupied, the high-energy one being empty. The temperature dependence of the localized ferromagnetism appears in the QDOS as a temperature-dependent shift of spectral weight between the low- and the high-energy peak.

  6. Standard model of the rare earths analyzed from the Hubbard I approximation

    NASA Astrophysics Data System (ADS)

    Locht, I. L. M.; Kvashnin, Y. O.; Rodrigues, D. C. M.; Pereiro, M.; Bergman, A.; Bergqvist, L.; Lichtenstein, A. I.; Katsnelson, M. I.; Delin, A.; Klautau, A. B.; Johansson, B.; Di Marco, I.; Eriksson, O.

    2016-08-01

    In this work we examine critically the electronic structure of the rare-earth elements by use of the so-called Hubbard I approximation. From the theoretical side all measured features of both occupied and unoccupied states are reproduced, without significant deviations between observations and theory. We also examine cohesive properties like the equilibrium volume and bulk modulus, where we find, in general, a good agreement between theory and measurements. In addition, we have reproduced the spin and orbital moments of these elements as they are reflected from measurements of the saturation moment. We have also employed the Hubbard I approximation to extract the interatomic exchange parameters of an effective spin Hamiltonian for the heavy rare earths. We show that the Hubbard I approximation gives results which are consistent with calculations where 4 f electrons are treated as core states for Gd. The latter approach was also used to address the series of the heavy/late rare earths. Via Monte Carlo simulations we obtained ordering temperatures which reproduce measurements within about 20 % . We have further illustrated the accuracy of these exchange parameters by comparing measured and calculated magnetic configurations for the heavy rare earths and the magnon dispersion for Gd. The Hubbard I approximation is compared to other theories of the electronic structure, and we argue that it is superior. We discuss the relevance of our results in general and how this makes it possible to treat the electronic structure of materials containing rare-earth elements, such as permanent magnets, magnetostrictive compounds, photovoltaics, optical fibers, topological insulators, and molecular magnets.

  7. 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.

  8. 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......

  9. Influence of excited configurations on the intensities of electric-dipole transitions of rare-earth ions

    NASA Astrophysics Data System (ADS)

    Dunina, E. B.; Kornienko, A. A.

    2014-05-01

    The theory of induced electric-dipole transitions of rare-earth ions in crystals and glasses is improved by taking into account the third-order effects of perturbation theory with respect to the energies of virtual excitations of 4 f electrons to the 5 d states. Since the energy regions of excited 4 f N - 15 d states are usually superimposed with the charge-transfer bands, the effects caused by a virtual transfer of an electron from the outer shells of ions of the surroundings (ligands) to the unfilled 4 f N shells are also considered. The Pr3+, Sm3+, and Eu3+ ions are considered as examples. It is found that some difficulties inherent in the Judd-Ofelt calculation scheme are successfully overcome. The agreement of the calculated results with the experimental data improves.

  10. 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.

  11. Crystal field parameters with Wannier functions: Application to rare-earth aluminates

    NASA Astrophysics Data System (ADS)

    Novák, P.; Knížek, K.; Kuneš, J.

    2013-05-01

    A method to calculate the crystal field parameters is proposed and applied to trivalent rare-earth impurities in yttrium aluminate and to Tb3+ ion in TbAlO3. To determine crystal field parameters local Hamiltonian expressed in the basis of Wannier functions is expanded in a series of spherical tensor operators. Wannier functions are obtained by transforming the Bloch functions calculated using the density functional theory based program. The results show that the crystal field is continuously decreasing as the number of 4f electrons increases and that the hybridization of 4f states with the states of oxygen ligands is important. The method contains a single adjustable parameter characterizing the 4f-ligand charge transfer. Theory is confronted with experiment for Nd3+ and Er3+ ions in the YAlO3 matrix and for the Tb3+ ion in TbAlO3, and a good agreement within a few meV is found.

  12. 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.

  13. High pressure phase transformations in yttrium and scandium: Relation to rare earths and actinides crystal structures

    NASA Astrophysics Data System (ADS)

    Grosshans, W. A.; Vohra, Y. K.; Holzapfel, W. B.

    1982-10-01

    The phase transformations in the 4d transition metal yttrium (Y) and the 3d transition metal scandium (Sc) have been studied under pressures up to 45 GPa by energy dispersive X-ray diffraction. The metal Y shows the complete rare earth crystal structure sequence i.e. hcp→Sm-type→dhcp→fcc with increasing pressure. This establishes experimentally the similarity of Y with heavy lanthanides, and that the rare earth crystal structure sequence is driven by s→d transfer without any significant contribution from 4f electrons. The metal Sc does not undergo the rare earth crystal structure sequence with pressure but shows above 20 GPa β-Neptunium (Np) structure (tetragonal, 4 atoms/cell). This structure remains stable up to the highest pressure of 45 GPa. The occurence of the high temperature β-Np structure in trivalent Sc combined with large thermal expansions of Np and plutonium (Pu) suggest that itinerant 5f electrons become localized at high temperature in Np and Pu close to melting. This Mott transition with temperature is similar to the one observed between Pu and americium (Am).

  14. Magnetic properties of RT2Zn20; R = rare earth, T = Fe, Co, Ru, Os and Ir

    SciTech Connect

    Jia, Shuang

    2008-01-01

    It is well known that rare earth intermetallic compounds have versatile, magnetic properties associated with the 4f electrons: a local moment associated with the Hund's rule ground state is formed in general, but a strongly correlated, hybridized state may also appear for specific 4f electronic configuration (eg. for rare earth elements such as Ce or Yb). On the other hand, the conduction electrons in rare earth intermetallic compounds, certainly ones associated with non hybridizing rare earths, usually manifest non-magnetic behavior and can be treated as a normal, non-interacted Fermi liquid, except for some 3d-transition metal rich binary or ternary systems which often manifest strong, itinerant, d electron dominant magnetic behavior. Of particular interest are examples in which the band filling of the conduction electrons puts the system in the vicinity of a Stoner transition: such systems, characterized as nearly or weakly ferromagnet, manifest strongly correlated electronic properties [Moriya, 1985]. For rare earth intermetallic compounds, such systems provide an additional versatility and allow for the study of the behaviors of local moments and hybridized moments which are associated with 4f electron in a correlated conduction electron background.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  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 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Structural and crystal chemical properties of rare-earth titanate pyrochlores

    SciTech Connect

    Farmer, James Matthew; Boatner, Lynn A; Chakoumakos, Bryan C; Du, Mao-Hua; Lance, Michael J; Rawn, Claudia J.; Bryan, Jeff C.

    2014-01-01

    Rare-earth titanates, RE2Ti2O7 (where RE = a rare-earth) with the pyrochlore structure continue to be investigated for use as potential stable host materials for nuclear and actinide-rich wastes. Accordingly, the present work is directed towards the elucidation of the fundamental structural, physical, and thermochemical properties of this class of compounds. Single-crystals of the rare earth pyrochlores were synthesized using a high-temperature flux technique and were subsequently characterized using single-crystal X-ray diffraction. The cubic lattice parameters display an approximately linear correlation with the RE-site cation radius. Theoretical calculations of the lattice constants and bond lengths of the subject materials were carried out using density functional theory, and the results are compared to the experimental values. The Sm and Eu titanates exhibit a covalency increase between the REO8 and TiO6 polyhedra resulting in a deviation from the increasing linear lattice parameter through the transition series. Gd2Ti2O7 with the 4f7 half-filled f-orbital Gd3+ sub-shell exhibits the lowest 48f oxygen positional parameter. The coefficient of thermal expansion for the rare-earth titanate series is approximately linear, and it has a range of 10.1 11.2 x 10-6 C-1. Raman spectroscopy indicated that the ~530 cm-1 peak associated with the Ti-O stretching mode follows a general trend of decreasing frequency with increasing RE reduced mass.

  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. 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

  13. 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

  14. 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)

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. Magnetostriction and magnetism of rare earth intermetallic compounds: First principle study

    SciTech Connect

    Gavrilenko, V. I.; Wu, R. Q.

    2001-06-01

    Magnetism and magnetostriction of rare earth intermetallic compounds, GdCo{sub 2}, GdFe{sub 2}, NdCo{sub 2}, SmCo{sub 2}, and ErCo{sub 2}, have been studied by using the first principles full-potential linearized augmented plane-wave method with the generalized gradient approximation. The calculated magnetostriction coefficients agree well with experiment. The itinerant electrons of transition metal elements are found to play a significant role in magnetoelastic coupling. The strong anisotropy of magnetostriction in GdCo{sub 2} is explained. Contributions due to spatial anisotropic charge distribution of the incomplete 4f shells are calculated and discussed. {copyright} 2001 American Institute of Physics.

  20. Supramolecular structures and stereochemical versatility of azoquinoline containing novel rare earth metal complexes.

    PubMed

    El-Sonbati, A Z; Issa, R M; El-Gawad, A M Abd

    2007-09-01

    Rare earth complexes of 5-(phenylazo)-8-hydroxyquinoline (HL) of composition [M(L)(2)X.H(2)O] [where M=La, Ce, Pr, Nd and X=NO(3)(-) or NCS(-)] have been prepared and characterized on the basis of their chemical analyses, (1)H NMR, magnetic measurements, conductance, and visible and IR spectral data. Composition, conductance and IR spectral data of the complexes show that the HL acts as a bidentate monobasic ligand. The visible spectra of Pr(3+) and Nd(3+) show characteristic f-f transitions, and the nephelauxetic effect (1-beta) of these transitions has been evaluated. These data indicate the weak involvement of the 4f orbitals in complex formation.

  1. 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.

  2. External and internal magnetic-field effects on ferroelectricity in orthorhombic rare-earth manganites

    NASA Astrophysics Data System (ADS)

    Kuwahara, H.; Noda, K.; Akaki, M.

    2006-03-01

    We report the dielectric and magnetic properties of the perovskite (Eu,Y)MnO3 crystal without the presence of the 4f magnetic moments of the rare earth ions. The subject compound, (Eu,Y)MnO3, was controlled the average ionic radius of the A site so that it was the same as that of TbMnO3 in which the intriguing magnetoelectric effect has been recently discovered. The (Eu,Y)MnO3 crystal was found to have two distinct ferroelectric phases with polarization along the a (Pa, T<=23K) and c (Pc, 23K<=T<=25K) axes in the orthorhombic Pbnm setting in a zero magnetic field. In addition, we have demonstrated a magnetic-field-induced switching between these ferroelectric phases: Pa changed to Pc by the application of magnetic fields parallel to the a axis (Ha). In analogy to the case of Pc in TbMnO3, this result is possibly interpreted as follows. In the case of (Eu,Y)MnO3, Mn 3d spins rotate in the ab plane and Pa would emerge in a zero field. In the Ha, the field will force the spins to rotate in the bc plane, in which Pc would be stabilized. Magnetization measurements supported this interpretation: We confirmed the change of the spin rotation axis of the helix from the c axis to the a axis induced by application of the Ha because there is no 4f moments acting as an internal magnetic field and interacting with the 3d spins. Results obtained with other rare-earth manganites such as (Gd,Tb)MnO3 and (Eu,Ho)MnO3 will be presented.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  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. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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).

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

    SciTech Connect

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

    2014-04-03

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

  3. Rare-earth defect pairs in GaN: LDA+U calculations

    NASA Astrophysics Data System (ADS)

    Sanna, Simone; Schmidt, W. G.; Frauenheim, Th.; Gerstmann, U.

    2009-09-01

    The structural and electronic properties of rare-earth (RE) (Eu, Er, and Tm) related defect pairs in GaN have been investigated theoretically. Based on LDA+U total-energy calculations, their possible role in the luminescence process is discussed. In all charge states, the lanthanides show a strong preference for the Ga-lattice site, either as isolated substitutional or complexed with intrinsic defects. With respect to the electronic valence, a proper description of correlation effects of the strongly localized 4f electrons is shown to be crucial, especially if the REGa is paired with donors like the Ga interstitial or the N vacancy. The pairs formed by REGa substitutionals and vacancies or interstitials lower the symmetry and are found to locally distort the environment. By this, they are quite effective in relaxing the selection rules for the luminescent intra- 4f -shell transitions. While for n -type GaN, the next-nearest-neighbor pair REGaVGa pair is energetically favored, for p -type GaN, the REGaVN pair provides the most stable configuration and introduces shallow levels close to the conduction band, which can act as assistant levels in the luminescence process.

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

    DOE PAGES

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

    2014-04-03

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

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. 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.

  11. Structural transition in rare earth doped zirconium oxide: A positron annihilation study

    SciTech Connect

    Chakraborty, Keka; Bisoi, Abhijit

    2012-11-15

    Graphical abstract: New microstructural analysis and phase transition of rare earth doped mixed oxide compounds such as: Sm{sub 2−x}Dy{sub x}Zr{sub 2}O{sub 7} (where x = 0.0 ≤ x ≥ 2.0) that are potentially useful as solid oxide fuels, ionic conductors, optoelectronic materials and most importantly as radiation resistant host for high level rad-waste disposal, structural transition in the system is reported through positron annihilation spectroscopy as there is an indication in the X-ray diffraction analysis. Highlights: ► Zirconium oxide material doped with rare earth ions. ► The method of positron annihilation spectroscopy suggests a phase transition in the system. ► The crystal structure transformation from pure pyrochlore to defect fluorite type of structure is shown by X-ray diffraction results. -- Abstract: A series of compounds with the general composition Sm{sub 2−x}Dy{sub x}Zr{sub 2}O{sub 7} (where 0 ≤ x ≥ 2.0) were synthesized by chemical route and characterized by powder X-ray diffraction (XRD) analysis. The rare earth ion namely Sm{sup +3} in the compound was gradually replaced with another smaller and heavier ion, Dy{sup +3} of the 4f series, there by resulting in order–disorder structural transition, which has been studied by positron annihilation lifetime and Doppler broadening spectroscopy. This study reveals the subtle electronic micro environmental changes in the pyrochlore lattice (prevalent due to the oxygen vacancy in anti-site defect structure of the compound) toward its transformation to defect fluorite structure as found in Dy{sub 2}Zr{sub 2}O{sub 7}. A comparison of the changes perceived with PAS as compared to XRD analysis is critically assayed.

  12. Hybrid quantum nanophotonic devices for coupling to rare-earth ions

    NASA Astrophysics Data System (ADS)

    Miyazono, Evan; Hartz, Alex; Zhong, Tian; Faraon, Andrei

    2015-03-01

    With an assortment of narrow line-width transitions spanning the visible and IR spectrum and long spin coherence times, rare-earth doped crystals are the leading material system for solid-state quantum memories. Integrating these materials in an on-chip optical platform would create opportunities for highly integrated light-matter interfaces for quantum communication and quantum computing. Nano-photonic resonators with high quality factors and small mode volumes are required for efficient on-chip coupling to the small dipole moment of rare-earth ion transitions. However, direct fabrication of optical cavities in these crystals with current nanofabrication techniques is difficult and unparallelized, as either exotic etch chemistries or physical milling processes are required. We fabricated hybrid devices by mechanically transferring a nanoscale membrane of gallium arsenide (GaAs) onto a neodymium-doped yttrium silicon oxide (Y2SiO5) crystal and then using electron beam lithography and standard III-V dry etching to pattern nanobeam photonic crystal cavities and ring resonator cavities, a technique that is easily adapted to other frequency ranges for arbitrary dopants in any rare earth host system. Single crystalline GaAs was chosen for its low loss and high refractive index at the transition wavelength. We demonstrated the potential to evanescently couple between the cavity field and the 883 nm 4I9/2- 4F3/2 transition of nearby neodymium impurities in the host crystal by examining transmission spectra through a waveguide coupled to the resonator with a custom-built confocal microscope. The prospects and requirements for using this system for scalable quantum networks are discussed.

  13. Electronic structure and optical properties of rare earth hexaborides RB6 (R = La, Ce, Pr, Nd, Sm, Eu, Gd)

    NASA Astrophysics Data System (ADS)

    Singh, Nirpendra; Mohan Saini, Sapan; Nautiyal, Tashi; Auluck, S.

    2007-08-01

    The optical and electronic properties of the rare earth hexaborides RB6 (R = La, Ce, Pr, Nd, Sm, Eu, Gd) are studied using the full potential linearized augmented plane wave method. To account better for the on-site f-electron correlation, we adopted the Coulomb corrected local spin density approximation (LSDA+U) to the exchange correlation functional in the calculations. Our electronic structure calculation shows the overlapping of R 5d states and B 2p states at the X symmetry point. The magnetic moment of the ferromagnetic rare earth hexaborides increases with increasing 4f occupation. The calculated reflectivity and optical conductivity spectra are in agreement with the experimental data, although the structures in the calculated optical spectra are sharper.

  14. Spatial inhomogeneity in RFeAs(O,F)(R = Pr, Nd) determined from rare earth crystal field excitations.

    SciTech Connect

    Goremychkin, E. A.; Osborn, R.; Wang, C. H.; Lumsden, M. D.; McGuire, M. A.; Sefat, A. S.; Sales, B. C.; Mandrus, D.; Ronnow, H. M.; Su, Y.; Christianson, A. D.

    2011-06-27

    We report inelastic neutron-scattering measurements of crystal-field transitions in PrFeAsO, PrFeAsO{sub 0.87}F{sub 0.13}, and NdFeAsO{sub 0.85}F{sub 0.15}. Doping with fluorine produces additional crystal-field excitations, providing evidence that there are two distinct charge environments around the rare-earth ions, with probabilities that are consistent with a random distribution of dopants on the oxygen sites. The 4f electrons of the Pr{sup 3+} and Nd{sup 3+} ions have nonmagnetic and magnetic ground states, respectively, indicating that the enhancement of T{sub c} compared to LaFeAsO{sub 1-x}F{sub x} is not due to rare-earth magnetism.

  15. 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.

  16. Investigations into Rare Earth Oxide Use and Behaviour

    NASA Astrophysics Data System (ADS)

    Pryce, Owen

    2010-05-01

    The use of tracers which are applied to soils (distinguishable from tracers naturally present in soils) is increasing. Rare earth oxides (REOs) are the most prevalent of the sediment tracers used to tag soils in this manner. REOs have been applied in a host of different countries, at a range of scales e.g. over watersheds in the USA (Polyakov and Nearing, 2004; Kimoto et al., 2006); to examine rill erosion in China (Li et al., 2006); and to investigate the importance of topographical features in arable fields in the EU (Stevens and Quinton, 2008). Many successful experiments have been conducted using the suit of REO tracers, yielding important information on the behaviour of eroding sediments. However, the majority of publications have focused upon application of REO tracers, applying the tagging and extraction methods developed by Zhang et al., (2001, 2003). Furthermore, the techniques presently being used are known to generate methodological inaccuracies, such as tracer enrichment and non-uniform REO distributions on experimental plots, and analytical interferences when ICP-MS is used for tracer quantification. Unanswered questions regarding the use of REO tracers include: i) what is the effect upon soil of REO tagging?; ii) how is a uniform distribution of REOs in tagged soil achieved? iii) which is the most suitable way of applying REOs, to experimental plots of different scale, and to meet different objectives?; iv) which REOs are unsuitable for sediment tracing?; v) what is the most precise and efficient method of extracting REO tracers from sediments? vi) is the transport behaviour of REO tracers comparable to untagged soils? In an attempt to answer some of these questions, investigations have been conducted into the effect upon soil particle size of different methods of REO tagging. The ability of these methods to provide uniform distributions of REOs in the tagged soil was calculated. The accuracy and precision of published (Zhang et al., 2003; Stevens and

  17. 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.

  18. 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...

  19. 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...

  20. 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...

  1. Radiative and Nonradiative Transitions of the Rare-Earth Ions Tm(3+) and Ho(3+) in Y3AI5O12 and LiYF4

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Armagan, Guzin; Dibartolo, Baldassare; Modlin, Edward A.

    1995-01-01

    The optical spectra of rare earth ions in solids arise primarily from electric and magnetic dipole transitions between stark split multiplets of the 4f(sup N) electronic configuration. Electric dipole transitions are parity forbidden between levels of the 4f(sup N) configuration, while those of magnetic dipole origin are allowed. It is known from experiment, however, that the significant contributions to the intensities of most transitions are electric dipole in nature. Judd and Ofelt developed the theory of forced electric dipole transitions of rare-earth ions. This study is devoted to determining electric dipole transition probabilities and branching ratios for Tm(3+) and Ho(3+) ions in Yttrium Aluminum Garnet (YAG) and Yttrium Lithium Fluoride (YLF) using the theory of Judd and Ofelt. The radiative rates determined from the Judd-Ofelt analysis are used with measured lifetimes to find nonradiative rates of relaxation.

  2. 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

  3. 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

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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%.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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}.

  17. Red-green emitting and superparamagnetic nanomarkers containing Fe3O4 functionalized with calixarene and rare earth complexes.

    PubMed

    Khan, Latif U; Brito, Hermi F; Hölsä, Jorma; Pirota, Kleber R; Muraca, Diego; Felinto, Maria C F C; Teotonio, Ercules E S; Malta, Oscar L

    2014-12-15

    The design of bifunctional magnetic luminescent nanomaterials containing Fe3O4 functionalized with rare earth ion complexes of calixarene and β-diketonate ligands is reported. Their preparation is accessible through a facile one-pot method. These novel Fe3O4@calix-Eu(TTA) (TTA = thenoyltrifluoroacetonate) and Fe3O4@calix-Tb(ACAC) (ACAC = acetylacetonate) magnetic luminescent nanomaterials show interesting superparamagnetic and photonic properties. The magnetic properties (M-H and ZFC/FC measurements) at temperatures of 5 and 300 K were explored to investigate the extent of coating and the crystallinity effect on the saturation magnetization values and blocking temperatures. Even though magnetite is a strong luminescence quencher, the coating of the Fe3O4 nanoparticles with synthetically functionalized rare earth complexes has overcome this difficulty. The intramolecular energy transfer from the T1 excited triplet states of TTA and ACAC ligands to the emitting levels of Eu(3+) and Tb(3+) in the nanomaterials and emission efficiencies are presented and discussed, as well as the structural conclusions from the values of the 4f-4f intensity parameters in the case of the Eu(3+) ion. These novel nanomaterials may act as the emitting layer for the red and green light for magnetic light-converting molecular devices (MLCMDs).

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. [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.

  5. 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.

  6. 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

  7. 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

  8. Scintillation properties of rare-earth doped NaPO3-Al(PO3)3 glasses

    NASA Astrophysics Data System (ADS)

    Kuro, Tomoaki; Okada, Go; Kawaguchi, Noriaki; Fujimoto, Yutaka; Masai, Hirokazu; Yanagida, Takayuki

    2016-12-01

    We systematically investigated photoluminescence (PL), scintillation and dosimeter properties of rare-earth (RE) doped NaPO3-Al(PO3)3 (NAP) glasses. The NAP glasses doped with a series of RE ions (La-Yb, except Pm) with a consistent concentration (0.3 wt%) were prepared by the conventional melt-quenching method. The PL and scintillation decay time profiles showed fast (ns) and slow (μs or ms) components: the fast components from 15 to 100 ns were due to the host or 5d-4f transition emission, and the slow components from 15 μs to 5 ms were due to the 4f-4f transitions of RE. The thermally stimulated luminescence (TSL) was evaluated as a dosimeter property, and glow peaks appeared around 400 °C in all the samples. The TSL dose response function was examined in the dose range from 10 mGy to 10 Gy. Among the samples tested, Nd and Tb doped glasses showed higher signal by at least one order of magnitude than those of non-doped and other RE-doped samples. Over the dose range tested, the TSL signals are linearly related with the incident X-ray dose, showing a potential for practical applications.

  9. Rare earth dependent formation of PbF2 nanocrystals and its effect on the emission properties in oxyfluoride glasses

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung Hoon; Choi, Yong Gyu; Im, Won Bin; Chung, Woon Jin

    2013-03-01

    Oxyfluoride glasses doped with rare earth ions (Dy3+, Er3+ or Ho3+) were fabricated, and their visible and near infrared emissions were evaluated before and after the formation of β-PbF2 nanocrystals. Upon heat treatment of the parent glass to precipitate β-PbF2 nanocrystals, both the intensity and lifetime of radiative emissions from the Dy3+ ion were improved conspicuously, whereas changes in the emissions from Er3+ and Ho3+ turned out to be relatively insignificant. In addition to the hypersensitive nature of some 4 f↔4 f transitions of Dy3+, its spatial distribution inside the heat-treated oxyfluoride samples is believed to be responsible for this interesting observation. Our finding thus exemplifies the chemical effects of rare earth ions on the formation of nanocrystals via heat treating oxyfluoride glasses. Various probes including X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and Judd-Ofelt analysis were applied to elucidate the rare earth dependence of the fluoride nanocrystals within the oxyfluoride glasses.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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,...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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)

  10. Tracing irradiation-induced defect state of monazite by photoluminescence of rare Earth elements

    NASA Astrophysics Data System (ADS)

    Panczer, G.; Seydoux-Guillaume, A. M.; Montel, J. M.; Champagnon, B.

    2003-04-01

    Natural monazite is known in contrast to zircon, to almost never be found in the metamict state (Ewing, 1975) despite the fact that it received intensive radiation doses during geologic history by U and Th incorporation. Radiation damages in natural monazite seems to be limited to isolated domains within the crystal (Meldrum et al., 1998). Such property controlled the fact that the monazite lattice is easily healed even at low temperature as it was shown by TEM, XRD and Raman spectrometry (Seydoux-Guillaume et al., 2002). In order to estimate the degree of disorder and the healing of defects we used trivalent neodymium as an internal luminescent probe (Gaft et al., 2001). As a matter of fact the radiative electronic transitions of rare earth elements are very sensible to the short-range crystallographic order around them. Three natural monazites thermally untreated and quenched at 450, 500, 700, 800 and 1000^oC were analyzed under 514 nm Argon laser excitation with a Renishaw microspectrometer. Nd3+ emission was recorded in the range of 750 nm to 1 μm. The ^4F3/2 rightarrow ^4I9/2 transition parameters (position and width) show that 1) the position of the Stark levels do not change during thermal treatment, and 2) that the emission line widths decrease continuously (from 25 to 37%) from room temperature to 1000^oC. These results indicates that before annealing, sub sites of Nd were present with slight different environments induced by internal irradiation induced displacement of ions around them (short range disorder). After thermal treatment a continuous reorganization of the lattice occurs up to 1000^oC with quite strong rearrangement of the environment around the rare-earth leading to a decrease of the Nd sub site number. Thus, the luminescent probe reveals that defect healing continue at much higher temperatures than what was previously reported indicating that luminescence is a very sensible tool to appreciate the degree of disorder in mineral phases. Gaft M

  11. 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

  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. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Visible WGM emissions from rare earth ion doped ZnO microspheres

    NASA Astrophysics Data System (ADS)

    K, Fabitha; Rao, M. S. Ramachandra

    ZnO is known to be an ideal candidate for short wavelength range opto-electronic device applications due to its wide and direct bandgap (3.37 eV) and high excitonic binding energy (60 meV). Apart from the UV emission at ~380 nm (free exciton emission) ZnO also possesses a broad emission band centered at ~530 nm which is expected to be originated from the oxygen vacancy (Vo) defects. In rare earth (RE) ion doped ZnO, emissions originate from the 4f levels of RE ions will be obtained in addition to the characteristic emissions of ZnO. Small micro/nanostructures made of ZnO with high crystalline quality show unique characteristics in light emission, especially in lasing applications. A micro/ nanostructured ZnO crystal generally has a wurtzite structure with a natural hexagonal cross section, which serves as a WGM lasing micro cavity owing to its high reflective index (~2). However, there exists a potential optical loss at corners of hexagons; therefore, an isotropic structure like spheres may be a better candidate to achieve efficient light confinement. In our work, highly smooth micro spheres with different diameters were grown. Raman spectroscopy measurements confirm the hexagonal wurtzite structure of ZnO, SEM and AFM studies shows the smooth surfaced spheres. WGM lasing characteristics of ZnO spheres have been investigated using optical pumping with 488 nm laser in a micro-PL system. Details of the results will be presented.

  19. Magnetic anisotropy of rare-earth magnets calculated by SIC and OEP

    NASA Astrophysics Data System (ADS)

    Akai, Hisazumi; Ogura, Masako

    We have pointed out in our previous study that the chemical bonding between N and Sm plays an important role in the magnetic anisotropy change of Sm2Fe17 from in-plane to uniaxial ones caused by the introducing of N. This effect of N insertion was discussed in terms of change in the electronic structure calculated in the framework of LDA+SIC. The main issue here is whether the 4f states are dealt with properly in SIC. In the present study, we examine the applicability of SIC for the evaluation of the magnetic anisotropy of rare-earth (RE) magnets by comparing the results with various methods, in particular, the optimized effective potential (OEP) method. In this study, OEP is applied only on the RE sites. Admittedly, this is a drawback from the viewpoint of the consistent treatment of uncertainly inherent in the so-called KLI (Krieger-Li-Iafrate) constants. Putting this aside for the moment, we have calculated the electronic structure of RE magnets R2Fe17Nx and RCo5 (R=light RE), by OEP with exact-exchange (EXX) combined with Colle-Salvetti correlation. Our preliminary results have shown considerable differences between the SIC and OEP calculations. We will discuss the meaning of this discrepancy. This work was supported by the Elements Strategy Initiative Center for Magnetic Materials under the outsourcing project of MEXT and by a Grant-in-Aid for Scientific Research (No. 26400330) from MEXT.

  20. 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.

  1. 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.

  2. 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.

  3. [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.

  4. 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

  5. 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

  6. 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

  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. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. Ligand field density functional theory calculation of the 4f2→ 4f15d1 transitions in the quantum cutter Cs2KYF6:Pr3+.

    PubMed

    Ramanantoanina, Harry; Urland, Werner; Cimpoesu, Fanica; Daul, Claude

    2013-09-07

    Herein we present a Ligand Field Density Functional Theory (LFDFT) based methodology for the analysis of the 4f(n)→ 4f(n-1)5d(1) transitions in rare earth compounds and apply it for the characterization of the 4f(2)→ 4f(1)5d(1) transitions in the quantum cutter Cs2KYF6:Pr(3+) with the elpasolite structure type. The methodological advances are relevant for the analysis and prospection of materials acting as phosphors in light-emitting diodes. The positions of the zero-phonon energy corresponding to the states of the electron configurations 4f(2) and 4f(1)5d(1) are calculated, where the praseodymium ion may occupy either the Cs(+)-, K(+)- or the Y(3+)-site, and are compared with available experimental data. The theoretical results show that the occupation of the three undistorted sites allows a quantum-cutting process. However size effects due to the difference between the ionic radii of Pr(3+) and K(+) as well as Cs(+) lead to the distortion of the K(+)- and the Cs(+)-site, which finally exclude these sites for quantum-cutting. A detailed discussion about the origin of this distortion is also described.

  14. 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.

  15. Determination of the Moessbauer parameters of rare-earth nitroprussides: Evidence for new light-induced magnetic excited state (LIMES) in nitroprussides

    SciTech Connect

    Rusanov, V.; Stankov, S.; Ahmedova, A.; Trautwein, A.X.

    2009-05-15

    Nitroprussides of the rare-earth elements and some mixed rare-earth-sodium nitroprussides are studied by Moessbauer spectroscopy at ambient and lower temperatures. The high precision Moessbauer measurements reveal fine changes in the electronic configurations of the nitroprusside anions. A small increase of the quadrupole splitting reveals charge polarization effects in the nitroprusside anion caused by the oblate or prolate shape of the rare-earth ion and the lanthanide contraction. Despite the very large magnetic moment of holmium a magnetic phase transition is not observed down to 300 mK. The population of the metastable states SI and SII are evidenced in europium and scandium nitroprussides, and most likely they can be populated in all rare-earth nitroprussides. No distinct correlation between the Moessbauer parameters and the decay temperatures T{sub c} of the metastable states are found. In a very thin surface layer strong color change, which remains stable at room temperature, is detected. A quadrupole doublet with Moessbauer parameters typical for Fe(III), low spin S=1/2 state is related to a new colored photoproduct. The photoproduct is called light-induced magnetic excited state (LIMES) and explained with a photochemical redox reaction, which changes the valence, spin, and magnetic state of 4f-3d bimetallic complexes. - Graphical abstract: Rare-earth nitroprussides are studied by Moessbauer spectroscopy. Population of metastable states in a thin surface layer, and another state which remains stable at room temperature, are detected. The latter is a photoproduct which is called light-induced magnetic excited state (LIMES) and explained with a photochemical redox reaction, which changes the valence, spin, and magnetic state of 4f-3d bimetallic complexes.

  16. 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

  17. 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

  18. 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.

  19. 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).

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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. 

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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).

  18. 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.

  19. 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.

  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. 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.

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. Raman scattering on electronic levels in rare-earth iron borates RFe3(BO3)4

    NASA Astrophysics Data System (ADS)

    Klimin, S. A.; Popova, M. N.

    2016-12-01

    We have performed a Raman scattering study for single crystals of the rare-earth (RE) iron borates RFe3(BO3)4, R = Nd, Tb, Pr, in the range of temperatures 3-300 K. Electronic Raman scattering on the 4f levels of RE ions was registered, which enabled us to specify the schemes of crystal-field levels within ground multiplets of the RE ions. A splitting of the Kramers doublets in electronic Raman spectra of the neodymium iron borate testifies a magnetic ordering of the compound. Raman scattering from a coupled mode of the spin oscillations of the Fe and Nd subsystems was observed in NdFe3(BO3)4.

  12. Theoretical studies of strongly correlated rare-earth intermetallics RIn₃ and RSn₃ (R=Sm, Eu, and Gd)

    SciTech Connect

    Shafiq, M.; Ahmad, Iftikhar E-mail: dr.iftikhar@uom.edu.pk; Jalali Asadabadi, S.

    2014-09-14

    In this paper, the structural, elastic, and electronic properties of RIn₃ and RSn₃ (R = Sm, Eu, Gd) compounds have been investigated using the full potential linearized augmented plane wave plus local orbital method within the density functional theory. The structural properties are investigated using the LDA, GGA, and the band correlated LDA+U and GGA+U schemes. The lattice parameters are in good agreement with the available experimental results and the divalent state of Eu is also verified. The spin-orbit coupling is included in order to predict the correct electronic properties and splitting of 4f states of the rare earth elements is also incorporated. We calculated Bulk modulus, shear modulus, Young's modulus, anisotropic ratio, Kleinman parameters, Poisson's ratio, Lame's co-efficient, sound velocities for shear and longitudinal waves, and Debye temperature. We also predict the Cauchy pressure and B/G ratio in order to explore the ductile and brittle behaviors of these compounds.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Computational efficiences for calculating rare earth f^n energies

    NASA Astrophysics Data System (ADS)

    Beck, Donald R.

    2009-05-01

    RecentlyootnotetextD. R. Beck and E. J. Domeier, Can. J. Phys. Walter Johnson issue, Jan. 2009., we have used new computational strategies to obtain wavefunctions and energies for Gd IV 4f^7 and 4f^65d levels. Here we extend one of these techniques to allow efficent inclusion of 4f^2 pair correlation effects using radial pair energies obtained from much simpler calculationsootnotetexte.g. K. Jankowski et al., Int. J. Quant. Chem. XXVII, 665 (1985). and angular factors which can be simply computedootnotetextD. R. Beck and C. A. Nicolaides, Excited States in Quantum Chemistry, C. A. Nicolaides and D. R. Beck (editors), D. Reidel (1978), p. 105ff.. This is a re-vitalization of an older ideaootnotetextI. Oksuz and O. Sinanoglu, Phys. Rev. 181, 54 (1969).. We display relationships between angular factors involving the exchange of holes and electrons (e.g. f^6 vs f^8, f^13d vs fd^9). We apply the results to Tb IV and Gd IV, whose spectra is largely unknown, but which may play a role in MRI medicine as endohedral metallofullerenes (e.g. Gd3N-C80ootnotetextM. C. Qian and S. N. Khanna, J. Appl. Phys. 101, 09E105 (2007).). Pr III results are in good agreement (910 cm-1) with experiment. Pu I 5f^2 radial pair energies are also presented.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. [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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. Spatial inhomogeneity in RFeAs(O,F)(R=Pr,Nd) as revealed by studies of the rare earth crystal field excitations

    SciTech Connect

    Goremychkin, E. A.; Osborn, R.; Wang, Cuihuan; Lumsden, Mark D; McGuire, Michael A; Safa-Sefat, Athena; Sales, Brian C; Mandrus, David; Ronnow, H. M.; Su, Y.; Christianson, Andrew D

    2011-01-01

    We report inelastic neutron-scattering measurements of crystal-field transitions in PrFeAsO, PrFeAsO{sub 0.87}F{sub 0.13}, and NdFeAsO{sub 0.85}F{sub 0.15}. Doping with fluorine produces additional crystal-field excitations, providing evidence that there are two distinct charge environments around the rare-earth ions, with probabilities that are consistent with a random distribution of dopants on the oxygen sites. The 4f electrons of the Pr{sup 3+} and Nd{sup 3+} ions have nonmagnetic and magnetic ground states, respectively, indicating that the enhancement of T{sub c} compared to LaFeAsO{sub 1-x}F{sub x} is not due to rare-earth magnetism.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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)

  11. Doppler broadening of annihilation radiation measurements on 3d and 4f ferromagnets using polarized positrons

    NASA Astrophysics Data System (ADS)

    Kawasuso, A.; Maekawa, M.; Fukaya, Y.; Yabuuchi, A.; Mochizuki, I.

    2012-01-01

    We measured the Doppler broadening of annihilation radiation (DBAR) spectra of 3d (Fe, Co, and Ni) and 4f (Gd, Tb, and Dy) ferromagnets under a magnetic field by using spin-polarized positrons from a 68Ge-68Ga source. The results showed that the DBAR spectra of these metals have notably different magnetic-field dependences. The differences among Fe, Co, and Ni reflect that the upper minority spin bands of Fe and Co are nearly empty while those of Ni are still mostly occupied. For the rare-earth metals instead of the inner 4f electrons, 5d electrons that mediate the exchange interaction of the 4f electrons are primarily responsible for the magnetic-field effects on the DBAR spectra. Furthermore, the magnetic-field effects on the DBAR spectra of Gd, Tb, and Dy vanished above the Curie temperatures of the magnetic-phase transition for these metals.

  12. 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

  13. 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

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. (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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Effects of rare earth substitution on the optical properties of Bi{sub 2}MoO{sub 6} for coloring applications

    SciTech Connect

    Kumari, L. Sandhya; Prabhakar Rao, P.; Sameera, S.; James, Vineetha; Koshy, Peter

    2015-10-15

    Highlights: • New class of colored compounds BiREMoO{sub 6} (RE = Pr, Nd, Sm, Tb, Yb) was synthesized. • The substitution of RE gently red shifts the absorption edge to low energy side. • The differences in band gap depend on the position of the RE f bands. • The yellow colored compounds demonstrated good coloration to plastics. - Abstract: A new class of colored inorganic compounds, BiREMoO{sub 6} (RE = Pr, Nd, Sm, Tb and Yb) has been synthesized by a solid state route. The substitution of different rare earths for Bi{sup 3+} in Bi{sub 2}MoO{sub 6} produces visible light responsive compounds by gently red shifting the absorption edge to low energy side. The visible light absorption is based on the charge transfer transitions from O{sub 2p} valence band to conduction band made of primary Mo{sub 4d} and secondary Bi{sub 6p}. The substitution of RE{sup 3+} introduces partially occupied 4f electronic levels in between the band gap and the position of 4f level depend on the number of f electrons which allows tuning the band gap. Thus the rare earth substitution provides an opportunity to tailor the band gap of Bi{sub 2}MoO{sub 6} from 2.99 eV to 2.19 eV. The developed compounds exhibited different shades of yellow hue and demonstrated good coloration to plastics.

  11. 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.

  12. [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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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).

  18. 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.

  19. 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;...

  20. 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%).

  1. 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.

  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. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Method for preparing high cure temperature rare earth iron compound magnetic material

    DOEpatents

    Huang, Yuhong; Wei, Qiang; Zheng, Haixing

    2002-01-01

    Insertion of light elements such as H,C, or N in the R.sub.2 Fe.sub.17 (R=rare earth metal) series has been found to modify the magnetic properties of these compounds, which thus become prospective candidates for high performance permanent magnets. The most spectacular changes are increases of the Curie temperature, T.sub.c, of the magnetization, M.sub.s, and of coercivity, H.sub.c, upon interstitial insertion. A preliminary product having a component R--Fe--C,N phase is produced by a chemical route. Rare earth metal and iron amides are synthesized followed by pyrolysis and sintering in an inert or reduced atmosphere, as a result of which, the R--Fe--C,N phases are formed. Fabrication of sintered rare earth iron nitride and carbonitride bulk magnet is impossible via conventional process due to the limitation of nitridation method.

  11. 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.

  12. Oxidation resistance of aluminum-coated Fe-20Cr alloys containing rare earths or yttrium

    SciTech Connect

    Sigler, D.R. )

    1993-10-01

    Aluminum-coated Fe-20Cr (rare earth or yttrium) alloy foils were developed with oxidation resistance equivalent or superior to Fe-20Cr-5Al (rare earth or yttrium) alloy foils. The coated foils were made by dipping Fe-20Cr sheet into a salt-covered aluminum bath and then rolling the sheet to foil. Oxidation resistance of the coated foil was enhanced by adding rare earths or yttrium to the Fe-20Cr substrate alloys to insure oxide adherence. Test results indicate that only sufficient addition to tie up sulfur as a stable sulfide is needed in the Fe-20Cr alloy. Aluminum-coated foils show lower oxide growth rates than similar Fe-Cr-Al alloys, most likely the result of fewer impurities (particularly Fe) is the coated foils' growing oxide scale. 31 refs., 18 figs., 2 tabs.

  13. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Composite Material

    NASA Astrophysics Data System (ADS)

    Jia, You-Hua; Zhong, Biao; Ji, Xian-Ming; Yin, Jian-Ping

    2008-10-01

    We predict enhanced laser cooling performance of rare-earth-ions-doped glasses containing nanometre-sized ul-traBne particles, which can be achieved by the enhancement of local Geld around rare earth ions, owing to the surface plasma resonance of small metallic particles. The influence of energy transfer between ions and the particle is theoretically discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption is predicted. It is concluded that the absorption are greatly enhanced in these composite materials, the cooling power is increased as compared to the bulk material.

  14. Zero Rare-Earth Magnet Integrated Starter-Generator Development for Military Vehicle Applications

    DTIC Science & Technology

    2013-08-14

    generation is expected to reach and exceed 100kW. • Many electric machines capable of (≥ 100kW) output power rely on rare-earth elements such Nd, Sm , Dy...Steel • 1940’s – Alnico • 1950’s – Ferrite • 1960’s – Alnico 9 • 1960’s – SmCo − First RE PM’s • 1980’s – NdFeB • 2007 – LaCo Ferrite ...LaCo Ferrite Developmental Materials Zero Rare-Earth Ferrite Alnico Developmental Materials UNCLASSIFIED UNCLASSIFIED Permanent Magnet

  15. Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology.

    PubMed

    Moriwaki, Hiroshi; Yamamoto, Hiroki

    2013-01-01

    In recent years, rare earth elements (REEs) have been widely used in various modern technological devices and the global demand for REE has been increasing. The increased demand for REEs has led to environmental exposure or water pollution from rare earth metal mines and various commercial products. Therefore, the development of a safe technology for the separation and adsorption of REEs is very important from the perspective of green chemistry and environmental pollution. In this review, the application and mechanisms of microorganisms for the removal and extraction of REEs from aqueous solutions are described. In addition, the advantages in using microorganisms for REE adsorption and future studies on this topic are discussed.

  16. Quantization of electronic states in a rare-earth film: Gd/W(110)

    NASA Astrophysics Data System (ADS)

    Rader, O.; Shikin, A. M.

    2001-11-01

    A variety of distinct peaks occurs in photoemission spectra of ultrathin Gd on W(110) depending on the overlayer thickness, in particular a series of sharp peaks inside of a symmetry gap of the W band structure. Our phase-accumulation analysis assigns these structures to quantum-well states hitherto undetected in rare earths. This is of considerable importance since valence electrons mediate the magnetic coupling and determine the magnetic structure of rare-earth metals. As a first example of its impact, we demonstrate how the new quantum-well data help to resolve a current controversy concerning the nature of the Gd electronic structure.

  17. 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.

  18. Asymmetric Catalysis with bis(hydroxyphenyl)diamides/rare-earth metal complexes.

    PubMed

    Kumagai, Naoya; Shibasaki, Masakatsu

    2013-01-02

    A series of asymmetric catalysts composed of conformationally flexible amide-based chiral ligands and rare-earth metals was developed for proton-transfer catalysis. These ligands derived from amino acids provide an intriguing chiral platform for the formation of asymmetric catalysts upon complexation with rare-earth metals. The scope of this arsenal of catalysts was further broadened by the development of heterobimetallic catalytic systems. The cooperative function of hydrogen bonding and metal coordination resulted in intriguing substrate specificity and stereocontrol, and the dynamic nature of the catalysts led to a switch of their function. Herein, we summarize our recent exploration of this class of catalysts.

  19. 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.

  20. Enthalpies of Formation of Rare-Earth Orthovanadates, REVO4

    SciTech Connect

    Dorogova, M.; Navrotsky, Alexandra; Boatner, Lynn A

    2007-01-01

    Rare earth orthovanadates, REVO4, having the zircon structure, form a series of materials interesting for magnetic, optical, sensor, and electronic applications. Enthalpies of formation of REVO4 compounds (RE=Sc, Y, Ce Nd, Sm Tm, Lu) were determined by oxide melt solution calorimetry in lead borate (2PbO {center_dot} 2B2O3) solvent at 1075 K. The enthalpies of formation from oxide components become more negative with increasing RE ionic radius. This trend is similar to that obtained for the rare earth phosphates.

  1. Nondestructive photon detection using a single rare-earth ion coupled to a photonic cavity

    NASA Astrophysics Data System (ADS)

    O'Brien, Chris; Zhong, Tian; Faraon, Andrei; Simon, Christoph

    2016-10-01

    We study the possibility of using single rare-earth ions coupled to a photonic cavity with high cooperativity for performing nondestructive measurements of photons, which would be useful for global quantum networks and photonic quantum computing. We calculate the achievable fidelity as a function of the parameters of the rare-earth ion and photonic cavity, which include the ion's optical and spin dephasing rates, the cavity linewidth, the single-photon coupling to the cavity, and the detection efficiency. We suggest a promising experimental realization using current state-of-the-art technology in Nd:YVO4.

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

    PubMed

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

    2013-12-13

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

  3. METHOD OF SEPARATING TETRAVALENT PLUTONIUM VALUES FROM CERIUM SUB-GROUP RARE EARTH VALUES

    DOEpatents

    Duffield, R.B.; Stoughton, R.W.

    1959-02-01

    A method is presented for separating plutonium from the cerium sub-group of rare earths when both are present in an aqueous solution. The method consists in adding an excess of alkali metal carbonate to the solution, which causes the formation of a soluble plutonium carbonate precipitate and at the same time forms an insoluble cerium-group rare earth carbonate. The pH value must be adjusted to bctween 5.5 and 7.5, and prior to the precipitation step the plutonium must be reduced to the tetravalent state since only tetravalent plutonium will form the soluble carbonate complex.

  4. Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

    PubMed

    Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

    2014-11-17

    We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance.

  5. Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.

    PubMed

    Malkin, B Z; Lummen, T T A; van Loosdrecht, P H M; Dhalenne, G; Zakirov, A R

    2010-07-14

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R(2)Ti(2)O(7) (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions. The sets of crystal field parameters and anisotropic exchange coupling constants have been determined and their variations along the lanthanide series are discussed.

  6. Production yield of rare-earth ions implanted into an optical crystal

    SciTech Connect

    Kornher, Thomas Xia, Kangwei; Kolesov, Roman; Reuter, Rolf; Villa, Bruno; Wrachtrup, Jörg; Kukharchyk, Nadezhda; Wieck, Andreas D.; Siyushev, Petr; Stöhr, Rainer; Schreck, Matthias; Becker, Hans-Werner

    2016-02-01

    Rare-earth (RE) ions doped into desired locations of optical crystals might enable a range of novel integrated photonic devices for quantum applications. With this aim, we have investigated the production yield of cerium and praseodymium by means of ion implantation. As a measure, the collected fluorescence intensity from both implanted samples and single centers was used. With a tailored annealing procedure for cerium, a yield up to 53% was estimated. Praseodymium yield amounts up to 91%. Such high implantation yield indicates a feasibility of creation of nanopatterned rare-earth doping and suggests strong potential of RE species for on-chip photonic devices.

  7. Island of Rare Earth Nuclei with Tetrahedral and Octahedral Symmetries: Possible Experimental Evidence

    SciTech Connect

    Dudek, J.; Dubray, N.; Pangon, V.; Dobaczewski, J.; Olbratowski, P.; Schunck, N.

    2006-08-18

    Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral T{sub d} and/or octahedral O{sub h} symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around {sup 156}Gd and {sup 160}Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.

  8. Bioaccumulation of cerium and neodymium by Bacillus cereus isolated from rare earth environments of Chavara and Manavalakurichi, India.

    PubMed

    Challaraj Emmanuel, E S; Vignesh, V; Anandkumar, B; Maruthamuthu, S

    2011-10-01

    Rare earth elements (REEs) are among the common minerals in the Rare earth environment that are very precious and also enhance soil properties. The aim of this present study is to evaluate the accumulation of REEs by bacterial isolates of rare earth environment. Morphological and biochemical characterization were done for 37 bacterial isolates and also molecular studies were carried out using 16S rRNA sequencing method. The assessment of REEs composition in soil samples of Chavara and Manavalakurichi analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) showed the abundance of Cerium and Neodymium among lanthanides. The bioaccumulation study of rare earth elements by Bacillus cereus were accomplished employing FT-IR spectrum and ICP-OES analysis. The significant accumulation of rare earth elements especially Cerium and Neodymium was noticed in Bacillus cereus isolated from rare earth environment.

  9. Germanium and Rare Earth Element accumulation in woody bioenergy crops

    NASA Astrophysics Data System (ADS)

    Hentschel, Werner

    2016-04-01

    Germanium and REEs are strategic elements that are used for high tech devices and engineered systems, however these elements are hardly concentrated into mineable ore deposits. Since these elements occur widely dispersed in the earth crust with concentrations of several mgṡkg-1 (Ge 1.6 mgṡkg-1, Nd 25 mgṡkg-1) a new possibility to gain these elements could be phytomining, a technique that uses plants to extract elements from soils via their roots. Since knowledge about accumulating plant species is quite limited we conducted research on the concentrations of strategic elements in wood and leaves of fast growing tree species (Salix spec., Populus spec., Betula pendula, Alnus glutinosa, Fraxinus excelsior, Acer pseudoplatanus). In total 35 study sites were selected in the mining affected area around Freiberg (Saxony, Germany), differing in their species composition and degree of contamination with toxic trace metals (Pb, As, Cd). On each site plant tissues (wood and leaves, respectively) of different species were sampled. In addition soil samples were taken from a soil depth of 0 - 30 cm and 30 - 60 cm. The aim of our work was to investigate correlations between the concentrations of the target elements in plant tissues and soil characteristics like pH, texture, nutrients and concentrations in six operationally defined soil fractions (mobile, acid soluble, oxidizable, amorphic oxides, crystalline oxides, residual or siliceous). Concentrations of elements in soil extracts and plant tissues were measured with ICP-MS. The element Nd was selected as representative for the group of REEs, since this element showed a high correlation with the concentrations of the other REE We found that the concentration of Nd in the leaves (0.31 mgṡkg-1Nd) were several times higher than in herbaceous species (0.05 mgṡkg-1 Nd). The concentration of Ge in leaves were ten times lower than that of Nd whereas in herbaceous species Nd and Ge were in equal magnitude. Within the tree

  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. Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

    PubMed

    Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

    2014-01-01

    Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals.

  12. Mining and Exploitation of Rare Earth Elements in Africa as an Engagement Strategy in US Africa Command

    DTIC Science & Technology

    2011-06-17

    Globalsecurity.org, 2010, 2. 3 Geology.com, “REE Rare Earth Elements and their Uses,” Geology.com, http://geology.com/ articles /rare-earth-elements/ (accessed...controversy for decades.36 Jasper, in his article “Engineered Extinction” specifically mentions U.S. rare earth mining. He details the impact that...35 Justin Rohrlich, “How China Came to Dominate the Rare Earths Market,” December 29, 2010, http://www.minyanville.com/businessmarkets/ articles

  13. The origin of highly efficient selective emission in rare-earth oxides for thermophotovoltaic applications.

    PubMed

    Torsello, G; Lomascolo, M; Licciulli, A; Diso, D; Tundo, S; Mazzer, M

    2004-09-01

    Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.

  14. Magnetic Behaviour Of Some Oxide Glasses Doped With Rare Earth Ions

    NASA Astrophysics Data System (ADS)

    Pop, L.; Culea, E.; Bosca, M.

    2007-04-01

    Magnetic susceptibility data from Er3+ and Nd3+ ions embedded in some Bi2O3 - PbO glasses are reported for the 80-300 K temperature range. The temperature dependence of reciprocal magnetic susceptibility permitted to discuss the nature of complex interactions between rare earth ions localized in lead bismuthate glass matrices.

  15. Separation of the rare earths by anion-exchange in the presence of lactic acid

    NASA Technical Reports Server (NTRS)

    Faris, J. P.

    1969-01-01

    Investigation of adsorption of rare earths and a few other elements to an anion-exchange resin from mixed solvents containing lactic acid shows that the lanthanides are absorbed more strongly than from the alpha-hydroxyisobutryric acid system, but with less separation between adjacent members of the series.

  16. 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.

  17. Ferrimagnetism in the rare-earth iron garnets: a Monte Carlo study.

    PubMed

    Oitmaa, J; Falk, Thomas

    2009-03-25

    We investigate classical vector spin models of the rare-earth iron garnet ferrimagnets yttrium iron garnet (YIG) and gadolinium iron garnet (GdIG) using Monte Carlo simulations. Critical temperatures agree well with experiment. A compensation point is observed in GdIG, again in good agreement with experiment.

  18. Fluid rare earth element anlayses from wells RN-12 and RN-19, Reykjanes, Iceland

    SciTech Connect

    Andrew Fowler

    2015-07-24

    Results for fluid rare earth elment analyses from Reykjanes wells RN-12 and RN-19. The data have not been corrected for flashing. Samples preconcetrated using chelating resin with IDA functional group (InertSep ME-1). Analyzed using and Element magnetic sctor ICP-MS.

  19. Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

  20. Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents

    SciTech Connect

    Andrew Fowler

    2015-10-01

    Compilation of rare earth element and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.

  1. Method to Recover Media Ligand Losses During Sorption of Rare Earth Elements from Simulated Geothermal Brines

    SciTech Connect

    Dean Stull

    2016-05-24

    This document describes the method and results of an in-situ experiment used to confirm that ligand bleed from a sorptive media can be contained. The experiment focused on maintaining the media's sorption of rare earth elements (REE) obtained from a simulated geothermal brine doped with known mineral concentrations.

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

    SciTech Connect

    Christian, Jerry D.; Sterbentz, James W.

    2016-08-30

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

  3. [Geochemical characteristics of rare earth elements on sunflower growing area in the west of Jilin Province].

    PubMed

    Li, Shu-Jie; Dou, Sen; Wang, Li-Min; Liu, Zhao-Shun

    2011-07-01

    Soil and plant samples were collected from the sunflower growing area in the west of Jilin province. A variety of ancillary methods were used to determine the soil element content. Then the rare earth elements geochemistry in soil was studied, and the correlation of REEs in this region with other elements and the quality of plant was investigated. The results show that, (1) REE content of the soil in Nong'an is relatively higher to those in Daan and Tongyu. Distribution pattern of rare earth elements in soil for the right tilt of the light rare earth enrichment patterns which is consistent with the national distribution pattern of rare earth elements; (2) REE contents in the three studying areas in the soil are different, and this primarily relates to the soil parent materials; (3) The REEs which positively correlate with soil available potassium are Se, Fe2O3, Ti, P, Mn, Cu, Zn, Cr, Mo, B, F. The protein content of sunflower seeds has a negative correlation with REE. With the exception of Lu, all REEs show a similar correlation.

  4. Ternary rare earth-lanthanide sulfides. [Re = Eu, Sm or Yb

    DOEpatents

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

    1986-03-06

    Disclosed is a new ternary rare earth sulfur compound having the formula La/sub 3-x/M/sub x/S/sub 4/, where M is europium, samarium, or ytterbium, with x = 0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000/sup 0/C.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rare earths elements (REEs) are essential raw materials for the emerging green (low-carbon) energy technologies and ‘smart’ electronic devices. Global REE demand is slated to grow at a compound annual rate of 5% by 2020. Such high growth rate would require a steady supply base of REEs in the long ru...

  6. Thermal treatment for increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, John D.; McMasters, O. D.

    1989-07-18

    Magnetostrictive rods formed from rare earth-iron alloys are subjected to a short time heat treatment to increase their Magnetostrictive response under compression. The heat treatment is preferably carried out at a temperature of from 900.degree. to 1000.degree. C. for 20 minutes to six hours.

  7. Thermal treatment for increasing magnetostrictive response of rare earth-iron alloy rods

    DOEpatents

    Verhoeven, J.D.; McMasters, O.D.

    1989-07-18

    Magnetostrictive rods formed from rare earth-iron alloys are subjected to a short time heat treatment to increase their magnetostrictive response under compression. The heat treatment is preferably carried out at a temperature of from 900 to 1,000 C for 20 minutes to six hours.

  8. 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.

  9. Technical Information Resource on Rare Earth Elements Now Available to Public and Private Sector Stakeholders

    EPA Science Inventory

    A new EPA technical information resource, “Rare Earth Elements: A Review of Production, Processing, Recycling, and Associated Environmental Issues” has been produced as an introductory resource for those interested in learning more about REE mining and alternatives to meet demand...

  10. Process for synthesis of uniform colloidal particles of rare earth oxides

    SciTech Connect

    Matijevic, E.

    1991-05-14

    This patent describes an improvement in a process for the preparation of colloidal particles from rare earth salts by homogeneous precipitation techniques involving the forced hydrolysis of a hydrated cation at elevated temperatures. The improvement comprises: providing an aqueous solution, at an initial pH in the range of from about 4.5 to about 6, containing one or more hydrated rare earth cations; heating the aqueous solution containing one or more hydrated rare earth cations to a temperature in the range of from about 70{degrees} to about 90{degrees} C., so as to effect deprotonation of the hydrated rare earth cations under conditions conducive to control over the kinetics of formation of a precursor of the colloidal particles, and thereby generate in single burst of nuclei preliminary to formation of colloidal particles; aging the solution, to extent to such aging being based upon the growth of the nuclei to the desired particle size for the colloidal particles; and separating the colloidal particles upon attainment of the particles of the desired particle size.

  11. Preliminary study on using rare earth elements to trace non-point source phosphorous loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The environmental fate of phosphorus (P) is of concern as P is a primary cause of freshwater eutrophication. Rare earth elements (REEs) have been successfully used in the analysis of soil erosion and pollutant sources, as well as in the analysis of mineral genesis. To better understand the potential...

  12. Adsorption Behavior of Rare Earth Metal Cations in the Interlayer Space of γ-ZrP.

    PubMed

    Takei, Takahiro; Iidzuka, Kiyoaki; Miura, Akira; Yanagida, Sayaka; Kumada, Nobuhiro; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2016-10-04

    Adsorption competencies of rare earth metal cations in γ-zirconium phosphate were examined by ICP, synchrotron X-ray diffraction (SXRD), and ab initio simulation. The adsorption amounts are around 0.06-0.10 per zirconium phosphate. From the SXRD patterns of the adsorbed samples, the basal spacing estimated by c sin β increased linearly with an increasing ionic radius of rare earth metal cation, though a and b lattice constants show no change. These SXRD patterns can be classified into four groups that have different super lattices. The four superlattices have multiplicities of x131, x241, and x221 for the xabc axis, and the location of the rare earth metal cation in the original unit cell changes depending on the superlattice cell. In the x131 superlattice, Yb and Er occupied the site near the zirconium phosphate layer, though La and Ce in the x221 superlattice remained in the center position between the phosphate sheet. For the ab initio simulation of γ-ZrP with the typical rare earth metal cations (Tb, Eu, Dy, and La), the results of simulation show a similar tendency of the position estimated by SXRD refinements.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  14. RARE EARTH ELEMENTS: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES

    EPA Science Inventory

    Rare earth elements (REEs) are a group of 15 chemical elements in the periodic table, specifically the lanthanides. Two other elements, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...

  15. Mixing rare earth elements with manures to control phosphorus loss in runoff and track manure fate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concern over the enrichment of agricultural runoff with phosphorus (P) from land applied livestock manures has prompted the development of manure amendments that minimize P solubility. We evaluated the effect of mixing two rare earth chlorides, lanthanum chloride and ytterbium chloride, with poultr...

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

    SciTech Connect

    Hinatsu, Yukio Doi, Yoshihiro

    2016-07-15

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

  17. U.S. trade dispute with China over rare earth elements

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-03-01

    The U.S. government has brought a new trade case against China over rare earth elements (REE) as well as tungsten and molybdenum, President Barack Obama announced on 13 March. Japan and the European Union also have taken similar actions against China about REEs, which are a group of 17 chemically similar metallic elements that are used in a variety of electronic, optical, magnetic, and catalytic applications. REEs are plentiful in the Earth's crust, although China currently has about 37% of the world's reserves and accounts for more than 95% of the world's production of the elements, according to the British Geological Survey. The United States has requested consultations with China at the World Trade Organization (WTO) concerning "China's unfair export restraints on rare earths, as well as tungsten and molybdenum," the Office of the United States Trade Representative announced in a 13 March statement.

  18. Anion-exchangeable layered materials based on rare-earth phosphors: unique combination of rare-earth host and exchangeable anions.

    PubMed

    Geng, Fengxia; Ma, Renzhi; Sasaki, Takayoshi

    2010-09-21

    Layered materials, three-dimensional crystals built from stacking two-dimensional components, are attracting intense interest because of their structural anisotropy and the fascinating properties that result. However, the range of such layered materials that can exchange anions is quite small. Continuing efforts have been underway to identify a new class of anion-exchangeable materials. One major goal is the incorporation of rare-earth elements within the host because researchers expect that the marriage of rare-earth skeleton host and the exchangeable species within the interlayer will open up new avenues both for the assembly of layered materials and for the understanding of rare-earth element chemistry. Such lanthanide layered solids have industrial potential. These materials are also of academic importance, serving as an ideal model for studying the cationic size effect on structure stability associated with lanthanide contraction. In this Account, we present the work done by ourselves and others on this novel class of materials. We examine the following four subtopics regarding these layered anionic materials: (1) synthesis strategy and composition diversity, (2) structural features, (3) structure stability with relative humidity, and (4) applications. These materials can be synthesized either by hydrothermal reactions or by homogeneous precipitation, and a variety of anions can be intercalated into the gallery. Although only cations with a suitable size can form the layered structure, the possible range is wide, from early to late lanthanides. We illustrate the effect of lanthanide contraction on properties including morphology, lattice dimensions, and coordination numbers. Because each lanthanide metal ion coordinates water molecules, and the water molecules point directly into the gallery space, this feature plays a critical role in stabilizing the layered structure. In the 9-fold monocapped square antiprism structure, the humidity-triggered transition

  19. Low-temperature thermoluminescence spectra of rare-earth-doped lanthanum fluoride

    NASA Astrophysics Data System (ADS)

    Yang, B.; Townsend, P. D.; Rowlands, A. P.

    1998-01-01

    Lanthanum fluoride consistently shows two strong thermoluminescence glow peaks at low temperature in pure material near 90 and 128 K. A model is proposed in which these thermoluminescence peaks arise from the annealing of halogen defect sites, similar to the H and Vk centers of the alkali halides. Relaxation and decay of these defects in the pure LaF3 lattice results in broad-band intrinsic luminescence. Addition of rare-earth-impurity ions has two effects. First, the broad-band emission is replaced by narrow-band line emission defined by the trivalent rare-earth dopants. Second, it preferentially determines the formation of the halogen defect sites at impurity lattice sites and such sites appear to increase in thermal stability since the glow peak temperature increases from 128 K in the intrinsic material up to 141 K through the sequence of rare-earth dopants from La to Er. The temperature movement directly correlates with the changes in ionic size of the rare-earth ions, when allowance is made for differences in effective coordination number of the impurity ions. The data suggest two alternative lattice sites can be occupied. The model emphasizes that the intense thermoluminescence signals arise from internal charge rearrangements and annealing of defect complexes, rather than through the more conventional model of separated charge traps and recombination centers. At higher temperatures there is a complex array of glow peaks which depend not only on the dopant concentration but also are specific to each rare earth. Such effects imply defect models giving thermoluminescence within localized complexes and possible reasons are mentioned.

  20. PREFACE: IUMRS-ICA 2008 Symposium 'AA. Rare-Earth Related Material Processing and Functions'

    NASA Astrophysics Data System (ADS)

    Komatsu, Takayuki; Sato, Tsugio; Machida, Ken-ichi; Fukunaga, Hirotoshi

    2009-02-01

    Rare-earth related materials have been widely used in various advanced technologies and devices because of their novel functions such as excellent magnetic and optical properties. For the fabrication of the next generation of new rare-earth related materials with novel functions, it is necessary to design a wide range of materials from nano-scale to macro-scale and to develop novel techniques realizing such designs. Indeed, there has been great progress in the preparation, processing and characterization of new rare-earth materials covering magnetic alloys, inorganic and organic fluorescence materials. In the International Union of Materials Research Societies International Conference in Asia 2008 (IUMRS-ICA2008) (9-13 December, Nagoya, Japan), the symposium on 'AA: Rare-Earth Related Material Processing and Functions' was organized to provide an interdisciplinary forum for the discussion of recent advances in fabrication processing and applications of rare-earth related materials with various scaled and unique morphologies. Many papers were presented in the symposium, and some papers were accepted to be published in this proceeding after review. Editors: Takayuki KOMATSU (Nagaoka University of Technology, Japan) Tsugio SATO (Tohoku University, Japan) Ken-ichi MACHIDA (Osaka University, Japan) Hirotoshi FUKUNAGA (Nagasaki University, Japan) Jiro YAMASAKI (Kyushu Institute of Technology, Japan) Honjie ZHANG (Chinese Academy of Sciences, China) Chun Hua YAN (Peking University, China) Jianrong QIU (Zhejiang University, China) Jong HEO (Pohang University, Korea) Setsuhisa TANABE (Kyoto University, Japan) Hiroshi TATEWAKI (Nagoya City University, Japan) Tomokatsu HAYAKAWA (Nagoya Institute of Technology, Japan) Yasufumi FUJIWARA (Osaka University, Japan)

  1. Low-temperature thermoluminescence spectra of rare-earth-doped lanthanum fluoride

    SciTech Connect

    Yang, B.; Townsend, P.D.; Rowlands, A.P.

    1998-01-01

    Lanthanum fluoride consistently shows two strong thermoluminescence glow peaks at low temperature in pure material near 90 and 128 K. A model is proposed in which these thermoluminescence peaks arise from the annealing of halogen defect sites, similar to the H and V{sub k} centers of the alkali halides. Relaxation and decay of these defects in the pure LaF{sub 3} lattice results in broad-band intrinsic luminescence. Addition of rare-earth-impurity ions has two effects. First, the broad-band emission is replaced by narrow-band line emission defined by the trivalent rare-earth dopants. Second, it preferentially determines the formation of the halogen defect sites at impurity lattice sites and such sites appear to increase in thermal stability since the glow peak temperature increases from 128 K in the intrinsic material up to 141 K through the sequence of rare-earth dopants from La to Er. The temperature movement directly correlates with the changes in ionic size of the rare-earth ions, when allowance is made for differences in effective coordination number of the impurity ions. The data suggest two alternative lattice sites can be occupied. The model emphasizes that the intense thermoluminescence signals arise from internal charge rearrangements and annealing of defect complexes, rather than through the more conventional model of separated charge traps and recombination centers. At higher temperatures there is a complex array of glow peaks which depend not only on the dopant concentration but also are specific to each rare earth. Such effects imply defect models giving thermoluminescence within localized complexes and possible reasons are mentioned. {copyright} {ital 1998} {ital The American Physical Society}

  2. Antiferromagnetic transitions of osmium-containing rare earth double perovskites Ba{sub 2}LnOsO{sub 6} (Ln=rare earths)

    SciTech Connect

    Hinatsu, Yukio Doi, Yoshihiro; Wakeshima, Makoto

    2013-10-15

    The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. Powder X-ray diffraction measurements and Rietveld analysis show that Ln{sup 3+} and Os{sup 5+} ions are structurally ordered at the M site of the perovskite BaMO{sub 3}. Magnetic susceptibility and specific heat measurements show that an antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Magnetic ordering of Ln{sup 3+} moments occurs when the temperature is furthermore decreased. - Graphical abstract: The perovskite-type compounds containing both rare earth and osmium Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm–Lu) have been prepared. An antiferromagnetic ordering of Os{sup 5+} ions has been observed for Ba{sub 2}LnOsO{sub 6} (Ln=Pr, Nd, Sm, Eu, Gd, Lu) at 65–71 K. Measurements and analysis of the specific heat for Ba{sub 2}PrOsO{sub 6} show that magnetic ordering of the Pr{sup 3+} moments should have occurred at ∼20 K. Display Omitted.

  3. Infrared spectroscopy of rare-earth-doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Xing, Zhen; Huffman, T. J.; Xu, Peng; Qazilbash, M. M.; Saha, S. R.; Drye, Tyler; Paglione, J.

    2014-03-01

    Recently, rare-earth doping in CaFe2As2 has been used to tune its electronic, magnetic, and structural properties. The substitution of rare-earth ions at the alkaline-earth sites leads to the suppression of the spin-density wave (SDW) phase transition in CaFe2As2. For example, Pr substitution results in a paramagnetic metal in the tetragonal phase that is susceptible to a low temperature structural transition to a collapsed tetragonal phase. However, La-doped CaFe2As2 remains in the uncollapsed tetragonal structure down to the lowest measured temperatures. Both the uncollapsed and collapsed tetragonal structures exhibit superconductivity with maximum Tc reaching 47 K, the highest observed in inter-metallics albeit with a small superconducting volume fraction. In this work, we perform ab-plane infrared spectroscopy of rare-earth-doped CaFe2As2 at different cryogenic temperatures. Our aim is to ascertain the contributions of electron doping and chemical pressure to the charge and lattice dynamics of this iron-arsenide system.

  4. A Study on Removal of Rare Earth Elements from U.S. Coal Byproducts by Ion Exchange

    NASA Astrophysics Data System (ADS)

    Rozelle, Peter L.; Khadilkar, Aditi B.; Pulati, Nuerxida; Soundarrajan, Nari; Klima, Mark S.; Mosser, Morgan M.; Miller, Charles E.; Pisupati, Sarma V.

    2016-03-01

    Rare earth elements are known to occur in low concentrations in U.S. coals and coal byproducts. These low concentrations may make rare earth element recovery from these materials unattractive, using only physical separation techniques. However, given the significant production of rare earths through ion exchange extraction in China, two U.S. coal byproducts were examined for ion extraction, using ammonium sulfate, an ionic liquid, and a deep eutectic solvent as lixiviants. Extraction of rare earth elements in each case produced high recoveries of rare earth elements to the solution. This suggests that in at least the cases of the materials examined, U.S. coal byproducts may be technically suitable as REE ores. More work is required to establish economic suitability.

  5. Magnetic hyperfine interactions on Cd sites of the rare-earth cadmium compounds R Cd (R =Ce , Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. H. M.; Leite Neto, O. F. L. S.; Saitovitch, H.; Cavalcante, J. T. P. D.; Carbonari, A. W.; Saxena, R. N.; Bosch-Santos, B.; Pereira, L. F. D.; Mestnik-Filho, J.; Forker, M.

    2016-08-01

    This paper reports the investigation of the magnetic hyperfine field Bh f in a series of rare-earth (R ) cadmium intermetallic compounds R Cd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using 111In/111Cd as probe nuclei at Cd sites as well as first-principles calculations of Bh f at Cd sites in the studied compounds. Vapor-solid state reaction of R metals with Cd vapor and the 111In radioisotope was found to be an appropriate route of doping rare-earth cadmium compounds with the PAC probe 111In/111Cd. The observation that the hyperfine parameters depend on details of the sample preparation provides information on the phase preference of diffusing 111In in the rare-earth cadmium phase system. The 111Cd hyperfine field has been determined in the compounds R Cd for the R constituents Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, in several cases as a function of temperature. For most R constituents, the temperature dependence Bh f(T ) of 111Cd:R Cd is consistent with ferromagnetic order of the compound. DyCd, however, presents a remarkable anomaly: a finite magnetic hyperfine field is observed only in the temperature interval 35 K ≤ T ≤ 80 K which indicates a transition from ferromagnetic order to a spin arrangement where all 4 f -induced contributions to the magnetic hyperfine field at the Cd site cancel. First-principles calculation results for DyCd show that the (π , π , 0) antiferromagnetic configuration is energetically more favorable than the ferromagnetic. The approach used in the calculations to simulate the R Cd system successfully reproduces the experimental values of Bh f at Cd sites and shows that the main contribution to Bh f comes from the valence electron polarization. The de Gennes plot of the hyperfine field Bh f of 111Cd:R Cd vs the 4 f -spin projection (g -1 )J reflects a decrease of the strength of indirect 4 f -4 f exchange across the R series. Possible mechanisms are discussed and the experimental results indicate that

  6. Crystal Chemistry and Ceramic Processing of Rare Earth Chalcogenide Optical and Electronic Materials

    NASA Astrophysics Data System (ADS)

    Vaughan, Cheryl Marie

    1990-01-01

    The thesis is concerned with the development of new IR transmitting materials for the 8-14 micrometer atomspheric window. The strategy was to investigate, in detail, the synthesis, crystal chemistry, processing, optical, and electronic properties of the rare earth sulfide as candidate materials. The rare earths crystallize in five known structures. Study of their temperature stabilities during long reaction times showed that alpha (orthorhombic, Pnma) exists as the low temperature form, and gamma (cubic, I| 43d) exists as the high temperature form in the large rare earths. Delta (monoclinic, P2/m) exists in the smaller rare earths from Ho through Tm over all temperature ranges, and episilon (trigonal, R| 3c) forms from Yb and Lu. Beta (tetragonal, I4/acd), which is reported in literature as a mid temperature range, oxygen stabilized rare earth sulfide, appears to be an oxysulfide and is an intermediate step between the oxide and sulfide from La through Nd. Extremely fine-grained precursor oxides were synthesized by evaporative decomposition of solution. An ultrasonic dispersion of aqueous nitrate salts is misted into a hot walled furnace. The 2-5 micrometer resulting oxides were predominantly well-crystallized spherical particles. The sesquisulfides could be readily synthesized by direct reaction of the oxides with flowing H_2S in the presence of graphite. These reactive, fine-grained, EDS-derived sulfides could be sintered into ceramic compacts that achieved 92 -98 percent of theoretical density. Sintering temperatures from 1200^circ-1400 ^circC and time of 80-120 minutes in flowing H_2S produced the best ceramics. This method of preparation is superior to the method using stock 25-35 micrometer starting materials which only received 70-78 percent of theoretical density. The measurement of the electronic absorption edge yielded band gaps of 1.6-2.6 eV. The first-order transverse and longitudinal phonon frequencies obtained by specular reflectance FTIR spectroscopy

  7. Concentrations and health risk assessment of rare earth elements in vegetables from mining area in Shandong, China.

    PubMed

    Zhuang, Maoqiang; Zhao, Jinshan; Li, Suyun; Liu, Danru; Wang, Kebo; Xiao, Peirui; Yu, Lianlong; Jiang, Ying; Song, Jian; Zhou, Jingyang; Wang, Liansen; Chu, Zunhua

    2017-02-01

    To investigate the concentrations of rare earth elements in vegetables and assess human health risk through vegetable consumption, a total of 301 vegetable samples were collected from mining area and control area in Shandong, China. The contents of 14 rare earth elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The total rare earth elements in vegetables from mining and control areas were 94.08 μg kg(-1) and 38.67 μg kg(-1), respectively, and the difference was statistically significant (p < 0.05). The leaf vegetable had the highest rare earth elements concentration (984.24 μg kg(-1) and 81.24 μg kg(-1) for mining and control areas, respectively) and gourd vegetable had the lowest rare earth elements concentration (37.34 μg kg(-1) and 24.63 μg kg(-1) for mining and control areas, respectively). For both areas, the rare earth elements concentration in vegetables declined in the order of leaf vegetable > taproot vegetable > alliaceous vegetable > gourd vegetable. The rare earth elements distribution patterns for both areas were characterized by enrichment of light rare earth elements. The health risk assessment demonstrated that the estimated daily intakes (0.69 μg kg(-1) d(-1) and 0.28 μg kg(-1) d(-1) for mining and control areas, respectively) of rare earth elements through vegetable consumption were significantly lower than the acceptable daily intake (70 μg kg(-1) d(-1)). The damage to adults can be neglected, but more attention should be paid to the effects of continuous exposure to low levels of rare earth elements on children.

  8. Synthesis and characterization of rare-earth-free magnetic manganese bismuth nanocrystals

    SciTech Connect

    Shen, J; Cui, HZ; Huang, XP; Gong, MG; Qin, W; Kirkeminde, A; Cui, J; Ren, SQ

    2015-01-01

    Earth abundant manganese bismuth (MnBi) has long been of interest due to its largemagnetocrystalline anisotropy and high energy density for advanced permanent magnet applications. However, solution synthesis of MnBi phase is challenging due to the reduction potential mismatch between Mn and Bi elements. In this study, we show a versatile MnBi synthesis method involving the metal co-reduction followed by thermal annealing. The magnetically hard MnBi crystalline phase is then exchange coupled with magnetically soft cobalt coating. Our processing approach offers a promising strategy for manufacturing rare-earth-free magnetic nanocrystals.

  9. Synthesis and Characterization of Rare-earth-free Magnetic Manganese Bismuth Nanocrystals

    SciTech Connect

    Shen, Jian Q.; Cui, Huizhong; Huang, Xiaopeng; Gong, Maogang; Qin, Wei; Kirkeminde, Alec; Cui, Jun; Ren, Shenqiang

    2015-01-01

    Earth abundant manganese bismuth (MnBi) has long been of interest due to its large magnetocrystalline anisotropy and high energy density for advanced permanent magnet applications. However, solution synthesis of MnBi phase is challenging due to the reduction potential mismatch between Mn and Bi elements. In this study, we show a versatile MnBi synthesis method involving the metal co-reduction followed by thermal annealing. The magnetically hard MnBi crystalline phase is then exchange coupled with magnetically soft cobalt coating. Our processing approach offers a promising strategy for manufacturing rare-earth-free magnetic nanocrystals.

  10. Potassium, rubidium, strontium, barium, and rare-Earth concentrations in lunar rocks and separated phases.

    PubMed

    Philpotts, J A; Schnetzler, C C

    1970-01-30

    Concentrations of potassium, rubidium, strontium, barium, and rareearth elements have been determined by mass spectrometric isotope dilution for eight Apollo 11 lunar samples and for some separated phases. Potassiumn and ritbidium are at chondritic levels, strontium at 15 times, and barium and rare earths at 30 to 100 times chondritic levels. There are trace element similarities between the lunar samples and basaltic achondrites, terrestrial dredge basalts and the bulk earth. The trace element data appear to be consistent with these lunar samples being the result of limited partial fusion of some material similar to the brecciated eucrite meteorites.

  11. [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.

  12. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    PubMed

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis.

  13. Highly-dispersive spin gapless semiconductors in rare-earth-element contained quaternary Heusler compounds

    NASA Astrophysics Data System (ADS)

    Xu, Guizhou; You, Yurong; Gong, Yuanyuan; Liu, Er; Xu, Feng; Wang, Wenhong

    2017-03-01

    The acquisition of high mobility electrons in the zero-gap band of spin gapless semiconductors is crucial for their practical applications in spintronic devices. In this work, we propose to design a higher dispersive band by importing the rare-earth atom into the Heusler compounds. With first principles calculations, we identify several new spin gapless semiconductor candidates in the 21-electron LiMgPdSn-type quaternary Heusler alloys of (Y, La, Lu)CoCr/FeMn(Al, Ga). Densities of states for most of them reveal large band gaps in the minority spin direction, and relatively low states near the Fermi level in the majority spin. According to the electron projected band analysis, we find the import of the rare earth atom can enhance the sp component in the band across the Fermi level, which is conducive to form a linear-dispersive band that is promising to enhance the carrier mobility of spin gapless semiconductors.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  15. High-resolution VUV spectrometer/detector investigations of rare-earth pulsed plasma source (abstract)

    NASA Astrophysics Data System (ADS)

    Roberts, J. R.; Cromer, C. L.; Bridges, J. M.; Lucatorto, T. B.

    1985-05-01

    A 1.5-m grazing incidence spectrometer with a channel electron multiplier (CEMA) and electronic readout detector has been incorporated with a rare-earth target, pulsed plasma, continuum source. The spectrometer is compact and portable while maintaining high resolution. The CEMA detector consists of a single multichannel plate (MCP) with coned-shaped input pores which are cut at a 15-degree bias to improve efficiency at grazing angles. The source is a rare-earth plasma generated by a 10-J ruby laser producing intense continuum emission for wavelengths from 170 to 5 nm. This system will be used for both stationary and transient high-resolution atomic photoabsorption spectroscopy. The pulsed plasma source itself will be investigated for suitability as a radiometric transfer standard source. Preliminary results obtained with this integrated system will be discussed.

  16. Metastable cobalt nitride structures with high magnetic anisotropy for rare-earth free magnets.

    PubMed

    Zhao, Xin; Ke, Liqin; Wang, Cai-Zhuang; Ho, Kai-Ming

    2016-11-23

    Metastable structures of cobalt nitrides and Fe-substituted cobalt nitrides are explored as possible candidates for rare-earth free permanent magnets. Through crystal structure searches using an adaptive genetic algorithm, new structures of ConN (n = 3…8) are found to have lower energies than those previously discovered by experiments. Some structures exhibit large magnetic anisotropy energy, reaching as high as 200 μeV per Co atom (or 2.45 MJ m(-3)) based on first-principles density functional calculation. Substituting a fraction of Co with Fe helps in stabilizing new structures and at the same time further improves the magnetic properties. Our theoretical predictions provide useful insights into a promising system for the discovery of new rare-earth free magnets by experiment.

  17. Enthalpies of formation of rare earth orthovanadates, REVO{sub 4}

    SciTech Connect

    Dorogova, M.; Navrotsky, A. Boatner, L.A.

    2007-03-15

    Rare earth orthovanadates, REVO{sub 4}, having the zircon structure, form a series of materials interesting for magnetic, optical, sensor, and electronic applications. Enthalpies of formation of REVO{sub 4} compounds (RE=Sc, Y, Ce-Nd, Sm-Tm, Lu) were determined by oxide melt solution calorimetry in lead borate (2PbO.2B{sub 2}O{sub 3}) solvent at 1075 K. The enthalpies of formation from oxide components become more negative with increasing RE ionic radius. This trend is similar to that obtained for the rare earth phosphates. - Graphical abstract: Comparison of enthalpies of formation from oxides at 298 K for REVO{sub 4} [this work] and REPO{sub 4} compounds [S.V. Ushakov, K.B. Helean, A. Navrotsky, L.A. Boatner, J. Mater. Res. 16(9) (2001) 2623] vs. RE{sup 3+} ionic radius. Filled symbols indicate scheelite structure, open symbols zircon structure.

  18. β -decay properties of neutron-rich rare-earth isotopes

    NASA Astrophysics Data System (ADS)

    Sarriguren, P.

    2017-01-01

    In this paper, β -decay properties of even-even neutron-rich isotopes in the rare-earth mass region are studied within a microscopic theoretical approach based on a proton-neutron quasiparticle random-phase approximation. The underlying mean field is constructed self-consistently from a deformed Hartree-Fock calculation with Skyrme interactions and pairing correlations to which particle-hole and particle-particle residual interactions are added. Nuclei in this mass region participate in the astrophysical rapid neutron capture process and are directly involved in the generation of the rare-earth peak in the isotopic abundance pattern centered at A ≃160 . The energy distributions of the Gamow-Teller strength as well as the β -decay half-lives and the β -delayed neutron-emission probabilities are discussed and compared with the available experimental information and with calculations based on different approaches.

  19. 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.

  20. Current status and recent topics of rare-earth permanent magnets

    NASA Astrophysics Data System (ADS)

    Sugimoto, S.

    2011-02-01

    After the development of Nd-Fe-B magnets, rare-earth magnets are now essential components in many fields of technology, because of their ability to provide a strong magnetic flux. There are two, well-established techniques for the manufacture of rare earth magnets: powder metallurgy is used to obtain high-performance, anisotropic, fully dense magnet bodies; and the melt-spinning or HDDR (hydrogenation, disproportionation, desorption and recombination) process is widely used to produce magnet powders for bonded magnets. In the industry of sintered Nd-Fe-B magnets, the total amount of production has increased and their dominant application has been changed to motors. In particular, their use for motors in hybrid cars is one of the most attractive applications. Bonded magnets have also been used for small motors, and the studies of nanocomposite and Sm-Fe-N magnets have become widespread. This paper reviews the current status and future trend in the research of permanent magnets.