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Sample records for rare-earth iron alloys

  1. Preparing rare earth-silicon-iron-aluminum alloys

    International Nuclear Information System (INIS)

    Marchant, J.D.; Morrice, E.; Herve, B.P.; Wong, M.M.

    1980-01-01

    As part of its mission to assure the maximum recovery and use of the Nation's mineral resources, the Bureau of Mines, investigated an improved procedure for producing rare earth-silicon alloys. For example, a charge consisting of 681 grams of mixed rare-earth oxides, 309 grams of ferrosilicon (75 wt-pct Si), and 182 grams of aluminum metal along with a flux consisting of 681 grams of CaO and 45 grams of MgO was reacted at 1500 0 C in an induction furnace. Good slag-metal separation was achieved. The alloy product contained, in weight-percent, 53 RE, 28 Si, 11 Fe, and 4 Al with a rare earth recovery of 80 pct. In current industrial practice rare earth recoveries are usually about 60 pct in alloy products that contain approximately 30 wt-pct each of rare earths and silicon. Metallurgical evaluations showed the alloys prepared in this investigation to be as effective in controlling the detrimental effect of sulfur in steel and cast iron as the commercial rare earth-silicon-iron alloys presently used in the steel industry

  2. Production of rare earth-silicon-iron alloys

    International Nuclear Information System (INIS)

    Mehra, O.K.; Bose, D.K.; Gupta, C.K.

    1987-01-01

    At Metallurgy Division, BARC, improved procedures for producing rare earth-silicon alloys have been investigated. In these methods, reduction of mixed rare earth oxide by a ferro-silicon and aluminium mixture in combination with CaO-MgO flux/CaO-CaF 2 flux have been tried to prepare an alloy product with a higher rare earth recovery at a higher rare earth content than the present commercial production method. The rare earth recovery using CaO-CaF 2 was 85 per cent while in the case of CaO-MgO flux it was 76 per cent. The corresponding rare earth contents in the alloy correspond to 40 per cent and 55 per cent by weight respectively. (author)

  3. Elastic properties of magnetostrictive rare-earth-iron alloys

    International Nuclear Information System (INIS)

    Cullen, J.R.; Blessing, G.; Rinaldi, S.

    1978-01-01

    The elastic properties of certain magnetostrictive rare-earth-iron alloys, namely polycrystalline Tbsub(0.3)Dysub(0.7)Fesub(2), Smsub(0.88)Dysub(0.12)Fesub(2)and amorphous TbFesub(2), were investigated ultrasonically. In all cases two shear waves were observed propagating simultaneously when a magnetic field was applied perpendicular to the direction of propagation. A model to explain this behaviour, based on magnetic-elastic coupling within local regions of these disordered materials, is developed and discussed in two limiting cases: (i) strongly coupled regions for which an effective isotropic magneto-elastic coupling is appropriate, and (ii) materials for which the elastic properties of the conglomerate are determined by averaging over those of independent regions. Experimental results up to fields of 25 kOe on the alloys mentioned above are exhibited and compared with the limiting cases (i) and (ii). In the case of polycrystalline Tbsub(0.3)Dysub(0.7)Fesub(2) further comparison is made between the determination of the magneto-elastic coupling constants using this model and the determination by using the results of a previous single-crystal study. (author)

  4. Method of forming magnetostrictive rods from rare earth-iron alloys

    Science.gov (United States)

    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.

  5. Rare earth-iron-boron premanent magnets

    International Nuclear Information System (INIS)

    Ghendehari, M.H.

    1988-01-01

    This patent describes a method for producing rare earth-iron-boron permanent magnets containing added rare earth oxide, comprising the steps of: (a) mixing a particulate alloy containing at least one rare earth metal, iron, and boron with at least one particulate rare earth oxide; (b) aligning magnetic domains of the mixture in a magnetic field; (c) compacting the aligned mixture to form a shape; and (d) sintering the compacted shape

  6. Rare earth metal alloy magnets

    International Nuclear Information System (INIS)

    Harris, I.R.; Evans, J.M.; Nyholm, P.S.

    1979-01-01

    This invention relates to rare earth metal alloy magnets and to methods for their production. The technique is based on the fact that rare earth metal alloys (for e.g. cerium or yttrium) which have been crumbled to form a powder by hydride formation and decomposition can be used for the fabrication of magnets without the disadvantages inherent in alloy particle size reduction by mechanical milling. (UK)

  7. Preparation of hard magnetic materials based on nitrogenated rare-earth iron alloys

    International Nuclear Information System (INIS)

    Guilherme, Eneida da Graca

    1999-01-01

    Nd Fe 11 Ti, Nd Fe 10.5 Mo 1.5 and Nd Fe 10.75 Mo 1.25 alloys were synthesized by reduction-diffusion calciothermic process (RDC) from neodymium chloride (NdCl 3 ), iron, titanium, molybdenum and reduction agent (metallic calcium). The effect of process variables, like temperature, time, excess amount of NdCl 3 , heating rate, and composition variation of the Nd Fe 12-x Mo x (1 ≥ x ≥ 2). Mother alloys in which 1:12 phase is major were nitrogenated by gas-solid reaction with N 2 and by chemical reaction with sodium zide (Na N 3 ). In addition, the influence of reducing particle size of the powdered mother alloys in the nitrogenation step with Na N 3 were studied. As prepared and interstitially modified Nd Fe 11 Ti, Nd Fe 10.5 Mo 1.5 and Nd Fe 10.75 Mo 1.25 alloys with nitrogen , were characterized by X-ray diffraction, Moessbauer spectroscopy, thermomagnetic, SEM and EDS. Nitrogenation by gas-solid reaction with N 2 is found to be not promising, since resulted Curie temperatures (Tc) were lower than literature values. However, nitrogenation by chemical reaction with Na N 3 was efficient with higher or same Tc than previous reported results. The average increases on Tc and volumetric expansion were 200 deg C and 4%, respectively. Milling of the mother alloys before nitrogenation at 330 deg C is preferred because reaction kinetics is enhanced. Nevertheless, at 450 deg C, a competition between the interstitially modified compound formation (alloy + N) and alloy dissociation has occurred, resulting in a Fe-α phase increase. (author)

  8. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...

  9. Generation and Characterization of Anisotropic Microstructures in Rare Earth-Iron-Boron Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Oster, Nathaniel [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The goal of this work is to investigate methods in which anisotropy could be induced in fine-grained alloys. We have identified two general processing routes to creating a fine, textured microstructure: form an amorphous precursor and devitrify in a manner that induces texture or form the fine, textured microstructure upon cooling directly from the liquid state. Since it is possible to form significant amounts of amorphous material in RE-Fe-B alloys, texture could be induced through biasing the orientationof the crystallites upon crystallization of the amorphous material. One method of creating this bias is to form glassy material and apply uniaxial pressure during crystallization. Experiments on this are presented. All of the work presented here utilizes melt-spinning, either to create precursor material, or to achieve a desired final microstructure. To obtain greater control of the system to process these materials, a study was done on the effects of heating the wheel and modifying the wheel’s surface finish on glass formation and phase selection. The second general approach—creating the desired microstructure directly from the liquid—can be done through directional rapid solidification. In particular, alloys melt-spun at low tangential wheel speeds often display directional columnar growth through a portion of the ribbon. By refining and stabilizing the columnar growth, a highly textured fine microstructure is achieved. The effects of adding a segregating element (Ag) on the columnar growth are characterized and presented.

  10. Rare earths and rare earth alloys electrolytic preparation process and device for this process

    International Nuclear Information System (INIS)

    Seon, F.; Barthole, G.

    1986-01-01

    Electrolysis of a molten salt of rare earth or rare earth alloy for preparation of the metal or alloy is described. The molten salt bath comprises at least a rare earth chloride, at least an alkaline or alkaline earth chloride and at least an alkaline or alkaline earth fluoride [fr

  11. Oxygen stabilized rare-earth iron intermetallic compounds

    International Nuclear Information System (INIS)

    Dariel, M.P.; Malekzadeh, M.; Pickus, M.R.

    1975-10-01

    A new, oxygen-stabilized intermetallic compound was identified in sintered, pre-alloyed rare-earth iron powder samples. Its composition corresponds to formula R 12 Fe 32 O 2 and its crystal structure belongs to space group Im3m. The presence of these compounds was observed, so far, in several R--Fe--O systems, with R = Gd, Tb, Dy, Ho, Er, and Y

  12. Enhanced magnetoelectric effects in composite of piezoelectric ceramics, rare-earth iron alloys, and shape-optimized nanocrystalline alloys.

    Science.gov (United States)

    Zhang, Jitao; Li, Ping; Wen, Yumei; He, Wei; Yang, Aichao; Lu, Caijiang

    2014-03-01

    An enhancement for magnetoelectric (ME) effects is studied in a three-phase ME architecture consisting of two magnetostrictive Terfenol-D (Tb(0.3)Dy(0.7)Fe(1.92)) plates, a piezoelectric PZT (Pb(Zr,Ti)O3) plate, and a pair of shape-optimized FeCuNbSiB nanocrystalline alloys. By modifying the conventional shape of the magnetic flux concentrator, the shape-optimized flux concentrator has an improved effective permeability (μ(eff)) due to the shape-induced demagnetizing effect at its end surface. The flux concentrator concentrates and amplifies the external magnetic flux into Terfenol-D plate by means of changing its internal flux concentrating manner. Consequently, more flux lines can be uniformly concentrated into Terfenol-D plates. The effective piezomagnetic coefficients (d(33m)) of Terfenol-D plate and the ME voltage coefficients (α(ME)) can be further improved under a lower magnetic bias field. The dynamic magneto-elastic properties and the effective magnetic induction of Terfenol-D are taken into account to derive the enhanced effective ME voltage coefficients (α(ME,eff)), the consistency of experimental results and theoretical analyses verifies this enhancement. The experimental results demonstrate that the maximum d(33m) in our proposed architecture achieves 22.48 nm/A under a bias of 114 Oe. The maximum α(ME) in the bias magnetic range 0-900 Oe reaches 84.73 mV/Oe under the low frequency of 1 kHz, and 2.996 V/Oe under the resonance frequency of 102.3 kHz, respectively. It exhibits a 1.43 times larger piezomagnetic coefficient and a 1.87 times higher ME voltage coefficient under a smaller magnetic bias of 82 Oe than those of a conventional Terfenol-D/PZT/Terfenol-D composite. These shape-induced magnetoelectric behaviors provide the possibility of using this ME architecture in ultra-sensitive magnetic sensors.

  13. Evaluation and economics aspects of the lying of rare earth and iron-alloys in the Seis Lagos Carbonatite Complex-Amazonas-Brazil

    International Nuclear Information System (INIS)

    Wetterle Bonow, C. de; Issler, R.S.

    1980-01-01

    New data on rare earth mineralization and iron-alloys as well as other rare elements in the Seis Lagos Carbonatite Complex are described. Drilling and field work data have permited to define in surface, subsidence zones (subsurface collapses), in the interval of 14.65 to 73.10 meters depth a carbonaceous clay sequence, sapropelic, neogenic, highly enriched in Re, Nb, Th, V, Zn and Be as well as Sc, Y, Ga, Co and Sn as by-products were detected. Sedimentogenic aspects of the enrichment of detect elements, the scintillometric survey, the reserve calculation, the detected elements, the by-products and the complementary study for the deposit are discussed and finaly a value of US$ 6.7 x 10 9 is estimated for the detect deposit. (Author) [pt

  14. Rare earths in iron and steelmaking and gaseous desulphurisation

    International Nuclear Information System (INIS)

    Kay, D.A.R.; Subramanian, S.V.; Meng, V.; Kumar, R.V.

    1985-01-01

    Rare earth (RE) additions, either as mischmetal or rare earth silicide, are used in many ladle treatment processes in modern ferrous metallurgy. In ironmaking they provide the basis for the control of graphite morphology in cast irons and in steelmaking additions are made to aluminum-killed steels for desulphurisation and the control of inclusion composition and morphology. Rare earth oxides may also be used in the desulphurisation of medium calorific value gaseous fuels and stack gases. In this paper, Ce-S-O and La-S-O phase stability diagrams are used to determine the role of the rare earths in the external processing of iron and steel, and gaseous desulphurisation

  15. Iron corrosion inhibition by phosphonate complexes of rare earth metals

    International Nuclear Information System (INIS)

    Kuznetsov, Yu.I.; Raskol'nikov, A.F.; Starobinskaya, I.V.; Alekseev, V.N.

    1993-01-01

    Capability is shown of trivalent rare earth nitrilotrimethylphosphonates (R= Ce, Pr, Nd, Eu, Lu, Y) to retard steel corrosion in soft water due to the formation of slightly soluble hydroxides on steel surface. The protective film is produced as a result of electrophilic substitution of nascent iron cations for rare earth ions in near the surface layer. The introduction of rare earth cations into the protective film is ascertained by Auger spectroscopy in combination with the argon spraying. A quantitative interrelation between the protective effectiveness and solubility product of rare earth hydroxides is revealed

  16. Nuclear orientation on rare earth nickel alloys

    International Nuclear Information System (INIS)

    Nishimura, K.

    1998-01-01

    A hyperfine interaction study of the light rare earth elements, Ce, Pr, Nd and Pm, in the rare earth nickel and CeNi 2 Al 5 compounds by means of the low temperature nuclear orientation is summarised. The magnitudes and directions of the magnetic hyperfine fields obtained through measurements of γ-ray anisotropy and angular distributions reveal the magnetic structures of the ions. The experiments extracted peculiar results for the magnetic properties of the ions, and show certain novel features of the technique to the study of solid-state magnetism. Copyright (1998) Australian Journal of Physics

  17. Nanocrystallinity and magnetic property enhancement in melt-spun iron-rare earth-base hard magnetic alloys

    International Nuclear Information System (INIS)

    Davies, H.A.; Manaf, A.; Zhang, P.Z.

    1993-01-01

    Refinement of the grain size below ∼35 nm mean diameter in melt-spun FeNdB-base alloys leads to enhancement of remanent polarization, J r , above the level predicted by the Stoner-Wohlfarth theory for an aggregate of independent, randomly oriented, and uniaxial magnetic particles. This article summarizes the results of the recent systematic research on this phenomenon, including the influence of alloy composition and processing conditions on the crystallite size, degree of enhancement of J r , and maximum energy product (BH) max . It has been shown that the effect can also occur in ternary FeNdB alloys, without the addition of silicon or aluminum, which was originally thought necessary, providing the nanocrystallites are not magnetically decoupled by a paramagnetic second phase. Values of (BH) max above 160 kJ. m -3 have been achieved. The relationship between grain size, J r , intrinsic coercivity, J H c , and (BH) max are discussed in terms of magnetic exchange coupling, anisotropy, and other parameters. Recent extension of this work to the enhancement of properties in Fe-Mischmental-Boron-base alloys and to bonded magnets with a nanocrystalline structure is also described

  18. Resistivity and magnetoresistivity of amorphous rare-earth alloys

    Science.gov (United States)

    Borchi, E.; Poli, M.; De Gennaro, S.

    1982-05-01

    The resistivity and magnetoresistivity of amorphous rare-earth alloys are studied starting from the general approach of Van Peski-Tinbergen and Dekker. The random axial crystal-field and the magnetic correlations between the rare-earth ions are consistently taken into account. The characteristic features of the available experimental data are explained both of the case of random ferromagnetic and antiferromagnetic order.

  19. Extraction of rare earths from iron-rich rare earth deposits

    OpenAIRE

    Bisaka, K.; Thobadi, I.C.; Pawlik, C.

    2017-01-01

    Rare earth metals are classified as critical metals by the United Nations, as they have found wide application in the fabrication of magnets, particularly those used in green energy technologies which mitigate global warming. Processing of ores containing rare earth elements is complex, and differs according to the nature of each ore. In the conventional process, run of mine (ROM) ores are processed in a physical separation plant to produce a concentrate from which rare earth elements are ext...

  20. Research On Technology Of Making Rare Earth Alloy Having Rare Earth Content ≽30% From Ore (≽40% REO) Using Aluminum Thermal Technology In Arc Furnace

    International Nuclear Information System (INIS)

    Ngo Xuan Hung; Ngo Trong Hiep; Tran Duy Hai; Nguyen Huu Phuc

    2014-01-01

    Arc furnace was used to smelt materials consisting of rare earth ore having rare earth content of ≽40% REO, aluminum as the reducing agent and additives. Rare earth alloy was obtained with rare earth metal content of more than 30%. (author)

  1. Preparation of hard magnetic materials based on nitrogenated rare-earth iron alloys; Preparacao de materiais magneticamente duros a base de ligas de terra rara - ferro nitrogenadas

    Energy Technology Data Exchange (ETDEWEB)

    Guilherme, Eneida da Graca

    1999-07-01

    Nd Fe{sub 11}Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys were synthesized by reduction-diffusion calciothermic process (RDC) from neodymium chloride (NdCl{sub 3}), iron, titanium, molybdenum and reduction agent (metallic calcium). The effect of process variables, like temperature, time, excess amount of NdCl{sub 3}, heating rate, and composition variation of the Nd Fe{sub 12-x}Mo{sub x} (1 {>=} x {>=} 2). Mother alloys in which 1:12 phase is major were nitrogenated by gas-solid reaction with N{sub 2} and by chemical reaction with sodium zide (Na N{sub 3}). In addition, the influence of reducing particle size of the powdered mother alloys in the nitrogenation step with Na N{sub 3} were studied. As prepared and interstitially modified Nd Fe{sub 11} Ti, Nd Fe{sub 10.5} Mo{sub 1.5} and Nd Fe{sub 10.75} Mo{sub 1.25} alloys with nitrogen , were characterized by X-ray diffraction, Moessbauer spectroscopy, thermomagnetic, SEM and EDS. Nitrogenation by gas-solid reaction with N{sub 2} is found to be not promising, since resulted Curie temperatures (Tc) were lower than literature values. However, nitrogenation by chemical reaction with Na N{sub 3} was efficient with higher or same Tc than previous reported results. The average increases on Tc and volumetric expansion were 200 deg C and 4%, respectively. Milling of the mother alloys before nitrogenation at 330 deg C is preferred because reaction kinetics is enhanced. Nevertheless, at 450 deg C, a competition between the interstitially modified compound formation (alloy + N) and alloy dissociation has occurred, resulting in a Fe-{alpha} phase increase. (author)

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

    Science.gov (United States)

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

    2015-09-03

    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.

  3. On the corrosion of binary magnesium-rare earth alloys

    Energy Technology Data Exchange (ETDEWEB)

    Birbilis, N. [ARC Centre of Excellence for Design in Light Metals, Monash University (Australia); CAST Co-operative Research Centre (Australia); Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia)], E-mail: nick.birbilis@eng.monash.edu.au; Easton, M.A. [CAST Co-operative Research Centre (Australia); Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia); Sudholz, A.D. [ARC Centre of Excellence for Design in Light Metals, Monash University (Australia); Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia); Zhu, S.M. [CAST Co-operative Research Centre (Australia); Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia); Gibson, M.A. [CAST Co-operative Research Centre (Australia); CSIRO Division of Materials Science and Engineering (Australia)

    2009-03-15

    The corrosion properties of high-pressure die cast (HPDC) magnesium-rare earth (RE) based alloys have been studied. Binary additions of La, Ce and Nd to commercially pure Mg were made up to a nominal 6 wt.%. It was found that the intermetallic phases formed in the eutectic were Mg{sub 12}La, Mg{sub 12}Ce and Mg{sub 3}Nd, respectively. Results indicated that increasing RE alloying additions systematically increased corrosion rates. This was also described in the context of the electrochemical response of Mg-RE intermetallics - which were independently assessed by the electrochemical microcapillary technique. This study is a discrete effort towards revealing the electrochemical effect of carefully controlled binary alloying additions to magnesium in order to elucidate the microstructure-corrosion relationship more generally for HPDC Mg alloys. Such fundamental information is seen to not only be useful in understanding the corrosion of alloys which presently contain RE additions, but may be exploited in the design of magnesium alloys with more predictable corrosion behaviour. There is a special need to understand this relationship - particularly for magnesium that commonly displays poor corrosion resistance.

  4. Mechanical Properties of Magnesium-Rare Earth Alloy Systems: A Review

    Directory of Open Access Journals (Sweden)

    Sravya Tekumalla

    2014-12-01

    Full Text Available Magnesium-rare earth based alloys are increasingly being investigated due to the formation of highly stable strengthening phases, activation of additional deformation modes and improvement in mechanical properties. Several investigations have been done to study the effect of rare earths when they are alloyed to pure magnesium and other Mg alloys. In this review, the mechanical properties of the previously investigated different magnesium-rare earth based binary alloys, ternary alloys and other higher alloys with more than three alloying elements are presented.

  5. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

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

    2017-08-08

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

  6. Rare earths

    Energy Technology Data Exchange (ETDEWEB)

    Cranstone, D A

    1979-01-01

    Rare earth elements are commonly extracted from the minerals monazite, bastnaesite, and xenotine. New uses for these elements are constantly developing; they have found applications in glass polishing, television tube phosphors, high-strength low-alloy steels, magnets, catalysts, refractory ceramics, and hydrogen sponge alloys. In Canada, rare earths have been produced as byproducts of the uranium mining industry, but there was no production of rare earths in 1978 or 1979. The world sources of and markets for the rare earth elements are discussed.

  7. Research on manufacturing aluminum - rare earth alloy with a high content of rare earth (> 20% RE) from total rare earth oxides by thermit reduction

    International Nuclear Information System (INIS)

    Ngo Trong Hiep; Dam Van Tien; Tran Duy Hai; Ngo Xuan Hung and Ly Thanh Vu

    2004-01-01

    In this report, several theoretical principles of thermit reduction method used for metal oxides to obtain metals, ferroalloys and ligatua with technical purity are presented. Manufacture of aluminum-rare earth alloys by thermit reduction is also described in the report. Data that are generalized based on thermo-kinetic calculation of the thermit reduction and selection of technological flow-sheet based on thermal effect will partly clarify research results in investigating typical features of the process and identify measures to reduce metal loss in discharged slags. (author)

  8. Powder metallurgical processing of magnetostrictive materials based on rare earth-iron intermetallic compounds

    International Nuclear Information System (INIS)

    Malekzadeh, M.

    1978-01-01

    Procedures are described for fabrication of high density rare earth-iron magnetostrictive compounds by powder metallurgical techniques. The fabrication involves a sequence of steps which includes preparing the pre-alloyed compounds, pulverizing them into a fine powder, compacting in suitable sizes and shapes, and sintering. Samples prepared by these procedures are carefully characterized by scanning electron microscopy, x-ray diffraction, dilatometry, and magnetic measurements. Process steps are found to exert important influences upon densities, microstructure and magnetic properties attained after densification. Investigations on a number of these process steps, including milling time and medium, sintering, and magnetic powder alignment are described

  9. Coated air-stable cobalt--rare earth alloy particles and method

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloys. An organometallic compound which decomposes at a temperature below 500 0 C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating on the particles. (U.S.)

  10. Crystal field symmetry and magnetic interactions in rare earth-silver amorphous alloys

    International Nuclear Information System (INIS)

    Pappa, Catherine.

    1979-01-01

    A study has been made of the following rare earth based amorphous alloys: Ndsub(x)Agsub(100-x), Prsub(x)Agsub(100-x), Gdsub(x)Agsub(100-x), Tlsub(x)Agsub(100-x). In rare earth based amorphous alloys, the symmetrical distribution of the crystal field is very wide and hence not very sensitive to the content of the alloys. The existence of preponderant negative magnetic interactions leads to an upset magnetic order, the magnetization of a small volume not being nil. The magnetic behaviour of alloys with a small concentration of rare earths is governed by the existence of clusters of statistical origin, within which a rare earth ion has at least one other rare earth ion in the position of first neighbour. The presence of a high anisotropy at low temperatures make the magnetic interactions between clusters inoperative [fr

  11. An analytical electron microscopy characterization of melt-spun iron/rare-earth/boron magnetic materials

    International Nuclear Information System (INIS)

    Dickenson, R.C.; Lawless, K.R.; Hadjipanayis, G.C.

    1986-01-01

    Iron/rare-earth/boron permanent magnet materials have recently been developed to reduce the need for the strategic element cobalt, which was previously the primary component of high-energy magnets. These materials are generally produced by annealing rapidly solidified ribbons or by conventional powder metallurgy techniques. This paper reports results from an analytical electron microscopy characterization undertaken to establish the relationship between the magnetic properties and the microstructure of two iron/rare-earth/boron (Fe/RE/B) alloys. Ribbons of Fe 75 Pr 15 B 10 and Fe 77 Tb 15 B 8 were produced by melt-spinning. To obtain optimum magnetic properties, both alloys were then annealed at 700 0 C, the FePrB ribbons for 6 minutes and the FeTbB ribbons for 90 minutes. Foils for transmission electron microscopy were prepared by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit

  12. Intermetallic precipitation in rare earth-treated A413.1 alloy. A metallographic study

    International Nuclear Information System (INIS)

    Samuel, Agnes M.; Samuel, Fawzy H.

    2018-01-01

    The present study was performed mainly on A413.1 alloy. Measured amounts of La, Ce or La+Ce, Ti and Sr were added to the molten alloy in the form of master alloys. Samples sectioned from castings obtained from thermal analysis experiments were used for preparing samples for metallographic examination. The results show that addition of rare earth (RE) metals to Al-Si alloys increased the α-Al nucleation temperature and depressed the Al-Si eutectic formation temperature, thereby increasing the solidification range. Depending upon the alloying elements/additives, a large number of RE-based intermetallics could be formed: Al 4 (Ce,La), Al 13 (Ce,La) 2 Cu 3 , Al 7 (Cu,Fe) 6 (Ce,La) 6 Si 2 , Al 4 La, Al 2 La 5 Si 2 , Al 2 Ce 5 Si 2 , Al 2 (Ce,La) 5 Si 2 . Under an electron microscope, these phases appear in backscatter imaging mode in the form of thin grayish-white platelets on the dark gray Al matrix. The average thickness of these platelets is about 1.5 μm. When the alloy is grain refined with Ti-based master alloys, precipitation of a gray phase in the form of sludge is observed: Al 12 La 3 Ti 2 , or Al 12 (Ce,La) 3 Ti 2 . Regardless the alloy composition, the RE/Al ratios remain constant in each type of intermetallic. Rare earth metals have a strong affinity to react with Sr (resulting in partial modification of the eutectic Si particles) as well as some transition elements, in particular Ti and Cu. Iron has a very low affinity for interaction with RE metals. It is only confined to Fe-based intermetallics.

  13. Two main and a new type rare earth elements in Mg alloys: A review

    Science.gov (United States)

    Kong, Linghang

    2017-09-01

    Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

  14. Rare earth concentration in the primary Si crystal in rare earth added Al-21 wt. % Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.Y.; Kim, G.H. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Moon, I.G.; Choi, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering

    1998-07-03

    Al-Si alloys containing more than about 12 wt. % Si exhibit a hypereutectic microstructure, normally consisting of a primary silicon phase in an eutectic matrix. The primary silicon in normal hypereutectic alloys is usually very coarse and thus leads to poor properties to these alloys. Therefore, alloys with a predominantly coarse primary silicon crystal must be modified to ensure adequate mechanical strength and ductility. Further improvement of mechanical properties of these alloys can be achieved by the modification of eutectic microstructure. Therefore, development of a modifier or refiner that can produce both fine primary and eutectic Si is a major factor which can lead to significant enhancement of mechanical properties in hypereutectic Al-Si alloys. Refinement of primary silicon is usually achieved by the addition of phosphor to the melt. On the other hand, it is reported that the rare earth (RE) elements are capable of modifying the eutectic structure of cast Al-Si alloys. According to the literature, Phosphor acts as a heterogeneous nucleation site of Si crystal by forming AlP intermetallic particles at high temperature, i.e., above liquidus temperature of Al-Si alloy. Unlike phosphor, RE was not known to form a stable compound with Al that can act as a nucleation site at high temperature. Therefore, the role of RE as a refiner should be considered by examining the behavior of RE as a solute in the melt. The distribution of RE within the primary Si and in the matrix of the alloy will provide a clue to the role of RE on the modification of primary Si during solidification.

  15. Random magnetism in amorphous rare-earth alloys (invited)

    Science.gov (United States)

    Sellmyer, D. J.; Nafis, S.

    1985-04-01

    Several aspects of the magnetic transitions seen in rare-earth metallic glasses are discussed, particularly with reference to recent theoretical work. These include: (a) apparent double transitions observed in Gd glasses where exchange fluctuations are important, (b) evidence for a correlated speromagnetic state recently predicted by Chudnovsky and Serota, and (c) the analysis of a Tb glass with strong random anisotropy in terms of an Ising-type spin-glass transition.

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

    Science.gov (United States)

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

    2018-01-01

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

  17. Corrosion-electrochemical and mechanical properties of aluminium-berylium alloys alloyed by rare-earth metals

    International Nuclear Information System (INIS)

    Safarov, A.M.; Odinaev, Kh.E.; Shukroev, M.Sh.; Saidov, R.Kh.

    1997-01-01

    In order to study influence of rare earth metals on corrosion-electrochemical and mechanical properties of aluminium-berylium alloys the alloys contain 1 mass % beryllium and different amount of rare earth metals were obtained.-electrochemical and mechanical properties of aluminium-berylium alloys. The electrochemical characteristics of obtained alloys, including stationary potential, potentials of passivation beginning and full passivation, potentials of pitting formation and re passivation were defined.

  18. Intermetallic precipitation in rare earth-treated A413.1 alloy. A metallographic study

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Agnes M.; Samuel, Fawzy H. [Univ. du Quebec a Chicoutimi (Canada). Dept. des Sciences Appliquees; Doty, Herbert W. [General Motors, Pontiac, MI (United States). Materials Engineering; Valtierra, Salvador [Nemak, S.A., Garza Garcia (Mexico)

    2018-02-15

    The present study was performed mainly on A413.1 alloy. Measured amounts of La, Ce or La+Ce, Ti and Sr were added to the molten alloy in the form of master alloys. Samples sectioned from castings obtained from thermal analysis experiments were used for preparing samples for metallographic examination. The results show that addition of rare earth (RE) metals to Al-Si alloys increased the α-Al nucleation temperature and depressed the Al-Si eutectic formation temperature, thereby increasing the solidification range. Depending upon the alloying elements/additives, a large number of RE-based intermetallics could be formed: Al{sub 4}(Ce,La), Al{sub 13}(Ce,La){sub 2}Cu{sub 3}, Al{sub 7}(Cu,Fe){sub 6}(Ce,La){sub 6}Si{sub 2}, Al{sub 4}La, Al{sub 2}La{sub 5}Si{sub 2}, Al{sub 2}Ce{sub 5}Si{sub 2}, Al{sub 2}(Ce,La){sub 5}Si{sub 2}. Under an electron microscope, these phases appear in backscatter imaging mode in the form of thin grayish-white platelets on the dark gray Al matrix. The average thickness of these platelets is about 1.5 μm. When the alloy is grain refined with Ti-based master alloys, precipitation of a gray phase in the form of sludge is observed: Al{sub 12}La{sub 3}Ti{sub 2}, or Al{sub 12}(Ce,La){sub 3}Ti{sub 2}. Regardless the alloy composition, the RE/Al ratios remain constant in each type of intermetallic. Rare earth metals have a strong affinity to react with Sr (resulting in partial modification of the eutectic Si particles) as well as some transition elements, in particular Ti and Cu. Iron has a very low affinity for interaction with RE metals. It is only confined to Fe-based intermetallics.

  19. Microstructure and mechanical properties of multi-components rare earth oxide-doped molybdenum alloys

    International Nuclear Information System (INIS)

    Zhang Guojun; Sun Yuanjun; Zuo Chao; Wei Jianfeng; Sun Jun

    2008-01-01

    Pure molybdenum and molybdenum alloys doped with two- or three-components rare earth oxide particles were prepared by powder metallurgy. Both the tensile property and fracture toughness of the pure molybdenum and multi-components rare earth oxide-doped molybdenum alloys were determined at room temperature. The multi-components rare earth oxide-doped molybdenum alloys are fine grained and contain a homogeneous distribution of fine particles in the submicron and nanometer size ranges, which is why the molybdenum alloys have higher strength and fracture toughness than pure molybdenum. Quantitative analysis is used to explain the increase in yield strength with respect to grain size and second phase strengthening. Furthermore, the relationship between the tensile properties and microstructural parameters is quantitatively established

  20. Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Saleh A. Alkahtani

    2016-01-01

    Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

  2. Annealed coated air-stable cobalt--rare earth alloy particles

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloy. An organometallic compound which decomposes at a temperature below 500 0 C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating thereon. The coated particles are heated at a temperature ranging from 50 to 200 0 C for a period of time sufficient to increase their intrinsic coercive force by at least 10 percent. (U.S.)

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

    Science.gov (United States)

    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.

  4. Influence of rare earth additions on the oxidation resistance of chromia forming alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    1995-01-01

    The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O 2 and AISI 316L+Y 2 O 3 by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O 2 to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O 3 . The isothermal oxidation behavior of rare earth oxide covered Ni-20 Cr at 900 deg C

  5. Estimation of formation heat of rare earth and actinide alloys

    International Nuclear Information System (INIS)

    Shubin, A.B.; Yamshchikov, L.F.; Raspopin, S.P.

    1986-01-01

    A method for forecasting the enthalpy of formation of scandium, yttrium, lanthanum and lanthanides, thorium, uranium and plutonium alloys with a series of fusible metals (Al, Ga, In, Tl, Sn, Pb, Sb, Bi) is proposed. The obtained confidence internal value for the calculated Δ f H 0 values exceeds sufficiently the random error of the experimental determination of the rare metal alloy formation enthalpies. However, taking into account considerable divergences in results of Δ f H 0 determinations performed by different science groups, one may conclude, that such forecasting accuracy may be useful in the course of estimation calculations, especially, for actinide element alloys

  6. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...

  7. Low-field susceptibilities of rare earth spin glass alloys

    International Nuclear Information System (INIS)

    Sarkissian, B.V.B.

    1977-01-01

    Static susceptibility in various applied fields and AC susceptibility data on Sc 13% Gd and Sc 4.5% Tb spin glass alloys are reported. The data show that the sharp peak at the freezing temperature, Tsub(g), normally observed in the low-field susceptibility of spin glasses containing 3d magnetic impurities is observed here in the case of Gd, which is an S state solute, but not for Tb. On the contrary, for the Sc-Tb alloy a rather rounded maximum is observed which becomes slightly sharper with increasing applied magnetic fields. (author)

  8. Microstructure and properties of step aged rare earth alloy magnets

    International Nuclear Information System (INIS)

    Mishra, R.K.; Thomas, G.; Yoneyama, T.; Fukuno, A.; Ojima, T.

    1980-11-01

    Alloys with compositions Co-25.5 wt/o Sm-8 w/o Cu-15 w/o Fe-3 w/o Zr and Co-Sm-Cu-Fe-1.5 w/o Zr have been step aged to produce magnets with coercive force (iHc) in the range of 10 to 25k0e. The high coercive force magnets are typically aged at 800 to 850 0 C for 10 to 30 hours following the solution treatment at 1150 0 C. Subsequently, these are step aged to produce materials with high coercivity. The microstructure in all these alloys has a 2 phase cellular morphology with 2:17 phase surrounded by a 1:5 boundary phase. The long aging treatments at 800 to 850 0 C lead to coarsening of the two phase structure. The subsequent step-aging does not change the morphology, but only changes the chemical composition of the two phases. Best properties are obtained in materials with a coherent microstructure of optimum boundary phase thickness and optimum chemical composition. The highest values of iHc obtained so far are approx. 26k0e and approx. 16 k0e for the 3% Zr and 1.5% Zr alloys respectively. The best hard magnetic properties of (BH) max = 33 MG0e and iHc = 13k0e are for a 25% Sm-20% Fe-4 Cu-2% Zr alloy

  9. The two bands model for the high temperature conductivity of the binary rare earth alloys

    International Nuclear Information System (INIS)

    Borgiel, W.

    1983-09-01

    The formula for the high temperature spin disorder resistivity for the concentrated Asub(1-x)Bsub(x)C alloys where A,B is an element of Rare Earth (RE) is determined on the basis of two bands model and the coherent potential approximation (CPA). The conductivity given by the 5d bands coming from the RE compounds has been taken into account

  10. Rare earth conversion coatings grown on AA6061 aluminum alloys. Corrosion studies

    Energy Technology Data Exchange (ETDEWEB)

    Brachetti S, S. B. [Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo y Sor Juana I. de la Cruz, Col. Los Mangos, 89440 Ciudad Madero, Tanaulipas (Mexico); Dominguez C, M. A.; Torres H, A. M.; Onofre B, E. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - Altamira, Carretera Tampico-Puerto Industrial Altamira Km. 14.5, 89600 Altamira, Tamaulipas (Mexico); De la Cruz H, W., E-mail: mdominguezc@ipn.mx [UNAM, Centro de Nanociencias y Nanotecnologia, Apdo. Postal 2681, 22800 Ensenada, Baja California (Mexico)

    2014-07-01

    The present work is aimed to investigate the corrosion resistance of rare earth protective coatings deposited by spontaneous deposition on AA6061 aluminum alloy substrates. Coatings were deposited from water-based Ce(NO{sub 3}){sub 3} and La(NO{sub 3}){sub 3} solutions by varing parameters such as rare earth solution concentration, bath temperature and immersion time. The values of the Tafel slopes indicate that the cathodic process is favored by concentration polarization rather than activation polarization. Chemical and morphological characterizations of the surface before and after electrochemical evaluations were performed by X-ray photoelectron spectroscopy and scanning electron microscopy. (Author)

  11. Rare earth conversion coatings grown on AA6061 aluminum alloys. Corrosion studies

    International Nuclear Information System (INIS)

    Brachetti S, S. B.; Dominguez C, M. A.; Torres H, A. M.; Onofre B, E.; De la Cruz H, W.

    2014-01-01

    The present work is aimed to investigate the corrosion resistance of rare earth protective coatings deposited by spontaneous deposition on AA6061 aluminum alloy substrates. Coatings were deposited from water-based Ce(NO 3 ) 3 and La(NO 3 ) 3 solutions by varing parameters such as rare earth solution concentration, bath temperature and immersion time. The values of the Tafel slopes indicate that the cathodic process is favored by concentration polarization rather than activation polarization. Chemical and morphological characterizations of the surface before and after electrochemical evaluations were performed by X-ray photoelectron spectroscopy and scanning electron microscopy. (Author)

  12. Preparation of rare earth-cobalt magnet alloy by reduction-diffusion process

    International Nuclear Information System (INIS)

    Krishnan, T.S.

    1980-01-01

    Preparation of rare earth-cobalt alloys by reduction-diffusion (R-D) process is described. The process essentially involves mixing of the rare earth oxide and cobalt/cobalt oxide powders in proper proportion and high temperature reduction of the charge in hydrogen atmosphere, followed by aqueous leaching of the reduced mass to yield the alloy powder. Comparison is made of the magnetic properties of the R-D powder with those of the powder prepared by the direct melting (DM) route and it is observed from the reported values for SmCo 5 that the energy product of the R-D powder (approximately 22 MGOe) is only marginally lower than that of the directly melted alloy (approximately 25 MGOe). The paper also includes the results of studies carried out at the Bhabha Atomic Research Centre, Bombay, on the preparation of misch metal-cobalt alloy by the R-D process. (auth.)

  13. High-temperature superconducting phase in rare earth alloys

    International Nuclear Information System (INIS)

    Vedyaev, A.V.; Molodykh, O.Eh.; Savchenko, M.A.; Stefanovich, A.V.

    1984-01-01

    A possibility of high-temperature superconducting phase existence in rare e arth alloys with aluminium: TbAl-NdAl is predicted. Such a phase is shown t o exist at t approximately 40 k, however its existence is possible only in a nar row temperature range and it might be metastable. A possibility of a supercondu cting phase occurrence in spin glass is studied. It is shown that the first kin d phase transition to superconducting state may first occur under definite condi tions in the system. But the phase in question will be a low-temperature one be cause of rather inefficient elctron-phonon interaction. Further temperature dec rease would lead to an appearance of magnetic order and to disappearance of the superconductivity

  14. Preparation of rare earth and other metal alloys containing aluminum and silicon

    International Nuclear Information System (INIS)

    Mitchell, A.; Goldsmith, J.R.; Gray, M.

    1981-01-01

    A method is provided for making alloys of aluminum and silicon with a third metal which may be a rare earth or a member of groups 4b, 5b, or 6b of the periodic table. The flux system CaF 2 -CaO-Al 2 O 3 is used as a solvent to provide a reactive medium for the alloy-forming reactions. Aluminum is supplied as a reducing agent, and silicon is added as a sink for the alloying metal. The resulting alloy may be used in steels. (L.L.)

  15. Rare earth conversion coating on Mg-8.5Li alloys

    International Nuclear Information System (INIS)

    Yang Xiaowei; Wang Guixiang; Dong Guojun; Gong Fan; Zhang Milin

    2009-01-01

    The conversion coating formed by immersion in a solution containing rare earth salt on Mg-8.5Li alloy was studied and the corrosion resistance was evaluated as well. The surface morphology was observed by scanning electron microscopy (SEM), and the chemical composition was characterized by X-ray photoelectron spectroscopy (XPS). The corrosion behaviors of Mg-8.5Li alloy and conversion coating were assessed by means of potentiodynamic polarization curves, electrochemical impedance spectra (EIS) and immersion tests. The experimental results indicated that the coating with cracked morphology was homogeneous. It was mainly composed of La 2 O 3 , CeO 2 , Mn 2 O 3 and MnO 2 as detected by XPS. The results of electrochemical measurements and immersion tests revealed that the rare earth conversion coating possessed better corrosion resistance than bare alloy and chromate conversion coating.

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

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.

    1974-01-01

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

  17. Air-stable compact of cobalt-rare earth alloy particles and method

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable magnetic products. An organometallic compound which decomposes at a temperature below 500 0 C is mixed with particles of a transition metal-rare earth alloy. The resulting mixture is pressed to form a green body, which is then heated to decompose the organometallic compound to produce a metal vapor that deposits an interconnecting metal coating on the exposed surfaces of the pressed particles. (U.S.)

  18. CPA theory of the magnetization in rare earth transition metal alloys

    International Nuclear Information System (INIS)

    Szpunar, B.; Lindgaard, P.A.

    1976-11-01

    Calculations were made of the magnetic moment per atom of the transition metal and the rare earth metal in the intermetallic compounds, Gdsub(1-x)Nisub(x), Gdsub(1-x)Fesub(x), Gdsub(1-x)Cosub(x), and Ysub(1-x)Cosub(x). A simple model of the disordered alloy consisting of spins localized on the rare earth atoms and interacting with a narrow d-band is considered. The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline and amorphous intermetallic compounds. It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition metal pseudo spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states. (Auth.)

  19. Atomic absorption determination of iron and copper impurities in rare earth compounds

    International Nuclear Information System (INIS)

    Zelyukova, Yu.V.; Kravchenko, J.B.; Kucher, A.A.

    1978-01-01

    An extraction atomic absorption method for the determination of copper and iron impurities in rare earth compounds has been developed. The extraction separation of determined elements as hydroxy quinolinates with isobuthyl alcohol was used. It increased the sensitivity of these element determination and excluded the effect of the analysed sample. Cu, Te, Zn, Bi, Sn, In, Ga, Tl and the some other elements can be determined at pH 2.0-3.0 but rare earths are remained in an aqueous phase. The condition of the flame combustion does not change during the introduction of isobutyl extract but the sensitivity of the determination of the elements increased 2-3 times. The limit of Fe determination is 0.01 mg/ml and the limit of Cu determination is 0.014 mg/ml

  20. Low-field susceptibilities of rare-earth spin glass alloys

    International Nuclear Information System (INIS)

    Sarkissian, B.V.B.

    1978-01-01

    The low-field AC susceptibilities of the dilute rare-earth spin glass alloys Sc-Gd, Sc-Tb, Pr-Tb and Pr-Gd are reported and compared with low-field DC susceptibilities of the same samples. The similarities between their behaviour and that of Au-Fe spin glass alloys is also considered. When single-ion anisotropy is important, this can cause a dramatic broadening of the sharp peak. Broadening in the AC peak has also observed as the frequency of the deriving field is increased. These data can be qualitatively discussed in terms of a recent magnetic-cluster model for spin glasses. (author)

  1. Effect of crystalline electric fields and long-range magnetic order on superconductivity in rare earth alloys and compounds

    International Nuclear Information System (INIS)

    McCallum, R.W.

    1977-01-01

    The behavior of rare earth ions in a superconducting matrix has been studied in two distinct regimes. First, the effects of crystal field splitting of the 4f levels of a magnetic rare earth ion in the alloy system (LaPr)Sn 3 were investigated in the limit of low Pr 3+ concentration. In this system the rare earth impurity ions occupy random La sites in the crystal lattice. Second, the interaction of long-range magnetic order and superconductivity was explored in the ternary rare earth molybdenum chalcogenide systems. In these compounds the rare earth ions occupy periodic lattice sites in contrast to the random distribution of magnetic ions in dilute impurity alloy systems such as (LaPr)Sn 3

  2. The industry of metallic rare earths (R.E.)

    International Nuclear Information System (INIS)

    Poirier, P.

    1979-01-01

    The following subjects are discussed: rare earths resources (rare earths abondance and world reserves, main ores). Rare earths separation and purification (ionic exchange, solvent extraction). Metallic rare earths and their mixtures, metallothermic reduction of oxides or fluorides (Ca, Mg, Al, Si or rare earth metals), Co-reduction process for intermetallic compounds (SmCo 5 ). Industrial applications of metallic rare earths (traditional applications such as flints, nodular cast iron, steel refining, magnesium industrie, applications under development such as rare earths/cobalt magnets, LaNi 5 for hydrogen storage, special alloys (automotive post combustion), magnetostrictive alloys). Economical problems: rare earth are elements relatively abundant and often at easily accessible prices. However, this group of 15 elements are liable to certain economical restraints. It is difficult to crack ore for only one rare earth. Availability of one given rare earth must be associated with the other corresponding rare earths to absorb all the other rare earths in other applications. Rare-earth industry has a strong expanding rate. 20% per year average for 6 years with Rhone-Poulenc. Thanks to their exceptional, specific characteristics rare earths have a bright future particularly for their metals

  3. Higher order magnetic modulation structures in rare earth metal, alloys and compounds under extreme conditions

    International Nuclear Information System (INIS)

    Kawano, S.

    2003-01-01

    Magnetic materials consisting of rare earth ions form modulation structures such as a helical or sinusoidal structure caused by the oscillating magnetic interaction between rare earth ions due to RKKY magnetic interaction. These modulation structures, in some cases, develop further to higher order modulation structures by additional modulations caused by higher order crystalline electric field, magnetic interactions such as spin-lattice interaction, external magnetic field and pressure. The higher order modulation structures are observed in a spin-slip structure or a helifan structure in Ho, and a tilt helix structure in a TbEr alloy. Paramagnetic ions originated from frustration generate many magnetic phases under applied external magnetic field. KUR neutron diffraction groups have performed the development and adjustment of high-pressure instruments and external magnetic fields for neutron diffraction spectrometers. The studies of 'neutron diffraction under extreme conditions' by the seven groups are described in this report. (Y. Kazumata)

  4. The corrosion behaviour of rare-earth containing magnesium alloys in borate buffer solution

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, R. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); Ferreira, M.G.S. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); CICECO, Universidade de Aveiro (Portugal); Carmezim, M.J. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal); Instituto Politecnico de Setubal, ESTSetubal, DEM (Portugal); Montemor, M.F., E-mail: mfmontemor@ist.utl.p [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon (Portugal)

    2011-01-01

    In this work, the corrosion behaviour of magnesium alloys ZK31, EZ33 and WE54 was studied in sodium borate buffer solution at pH 9.2. The electrochemical processes were studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The composition and morphology of the alloys and corrosion products formed were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental findings highlighted the differences in the corrosion mechanisms of the different alloys tested. The results showed that the presence of rare-earth elements (RE) only increases the corrosion resistance when present in solid solution, as is the case of the WE54 alloy. At pH 9.2, an amorphous yttrium oxide/hydroxide thick film was formed, which possesses greater stability when compared to magnesium oxide/hydroxide. The role of RE in the corrosion mechanism was discussed.

  5. The role of sub-micron grain size in the development of rare earth hard magnetic alloys

    International Nuclear Information System (INIS)

    Davies, H.A.; Wang, Z.C.

    2004-01-01

    The magnetic properties of nanocrystalline melt spun rare earth-iron-boron alloys based on Nd or Pr and on Nd-Pr mixtures are compared for a wide range of RE:Fe ratio. Their magnetic properties are compared with those of corresponding alloy ribbons based on Nd. The Pr containing alloys have generally higher coercivity than their Nd counterparts because of the higher anisotropy constant of the Pr 2 Fe 14 B phase. Co substitution for Fe increases the Curie temperature and thermal stability for the nanophase alloys. Excellent magnetic property combinations were achieved for single phase Pr 12 (Fe 100-x Co x ) 82 B 6 (x=0-20) alloys, processed by overquenching and devitrification annealing. In contrast, in the case of nanocomposite Pr 10 (Fe 100-x Co x ) 84 B 6 alloys, based on Pr 2 Fe 14 B/α-Fe mixtures, only for 30% substitution of Fe by Co could useful enhancement of (BH) max be achieved, due to generally rather coarse α-Fe crystallites

  6. Structural order and magnetism of rare-earth metallic amorphous alloys

    International Nuclear Information System (INIS)

    Maurer, M.

    1984-01-01

    Local symmetry (as evaluated from the electric field gradient tensor) and radial distribution functions (obtained by EXAFS measurement) are determined in a series of amorphous rare-earth base alloys. Local order is found to increase with the extent of heteroatomic interactions. Various magnetic phases (including ferromagnetic, spin-glass, reentrant spin-glass) occur for europium alloys with simple metals (Mg, Zn, Cd, Al, Au, ...). This variety reflects the sensitivity of exchange interactions to the presence of non-s conduction electrons. Asperomagnetic structures are established for the Dy alloys. The crystalline electric field interactions at the Dy 3+ ions are interpreted with the help of local symmetry data. Quadratic axial and non-axial crystal field terms are sufficient and necessary in order to account for the hyperfine and bulk experimental results [fr

  7. Alloys of Pt and Rare Earths for the Oxygen Electroreduction Reaction

    DEFF Research Database (Denmark)

    Malacrida, Paolo

    This thesis presents the development and characterization of a new class of Pt alloys for catalyzing the Oxygen Reduction Reaction (ORR), in perspective of a future substitution of traditional Pt-based catalysts at the cathode of Polymer Electrolyte Membrane Fuel Cells (PEMFCs). Focused on spectr....... A number of bimetallic alloys based on Pt and a rare earth, like the Pt-Y system or more recently proposed Pt-lanthanide phases, have been tested and characterized. Polycrystalline Pt5La and Pt5Ce exhibited more than a factor of 3 enhancement in specific activity relative to state......-Y nanoparticles are among the most active ORR catalysts ever reported, although they lose 37 % of this activity after stability test. Similar to the case of polycrystals, after immersion in the acidic electrolyte and testing the active phase consists of a Pt shell surrounding an alloyed core. Also in this case...

  8. On the notch ductility of a magnesium-rare earth alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kondori, B., E-mail: bkondori.13034@tamu.edu [Department of Materials Science & Engineering, Texas A& M University, College Station, TX 77843 (United States); Benzerga, A.A. [Department of Materials Science & Engineering, Texas A& M University, College Station, TX 77843 (United States); Department of Aerospace Engineering, Texas A& M University, College Station, TX 77843 (United States)

    2015-10-28

    The room-temperature notch ductility of magnesium-rare earth alloy WE43 is investigated for two loading orientations. This material is endowed with quasi-isotropic plastic flow properties, higher strength and similar uniaxial ductility in comparison with other commercially available Mg alloys. The authors have recently shown that the notch ductility of a Mg–Al–Zn alloy is greater than its uniaxial ductility over a wide range of notch geometries. This paper investigates whether the same trends hold for WE43, discusses the orientation dependence of ductility and the propensity for intergranular fracture at high levels of hydrostatic tension. The latter mode of fracture is analyzed by means of detailed fractography in order to elucidate the role of grain-boundary particles and precipitates in the fracture process.

  9. Corrosion properties and corrosion evolution of as-cast AZ91 alloy with rare earth yttrium

    International Nuclear Information System (INIS)

    Luo, T.J.; Yang, Y.S.

    2011-01-01

    Highlights: → Minor addition of Y will increase the corrosion resistance of AZ91 alloy, and 0.3 wt.% Y is the optimum addition. → A film composed of Mg(OH) 2 , MgCO 3 , Al(OH) 3 and Al 2 O 3 is formed on the surface of AZ91 alloy with rare earth Y free. → The film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH) 2 and MgCO 3 without any Al(OH) 3 and Al 2 O 3 . → The relative quantity of MgCO 3 in the surface film of AZ91 + 0.3 wt.% Y is bigger than that of AZ91 alloy with Y free. → Y 2 O 3 phase is found in the surface film of alloy III, which benefits to stabilize the surface film. -- Abstract: The corrosion resistance property and the corrosion evolution of as-cast AZ91 alloy with rare earth Y addition are investigated by using immersion tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The results show that the proper amount of Y in the alloys can improve the corrosion resistance of AZ91 alloys effectively. With the increment of Y, the corrosion rate of the modified AZ91 alloys by Y addition was markedly less than that of AZ91 alloy. The corrosion rate of AZ91 alloy with 0.3 wt.% Y was the slightest, but further addition of Y content over 0.3 wt.% make the corrosion heavier. The XPS analysis suggests that the compound film of AZ91 alloy with 0.3 wt.% Y is mainly composed of Mg(OH) 2 and MgCO 3 without any Al(OH) 3 and Al 2 O 3 , in addition, Y 2 O 3 phase is found in the compound film of AZ91 alloy with 0.3 wt.% Y, which benefits to stabilize the surface film.

  10. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  11. Effect of rare earth elements on high cycle fatigue behavior of AZ91 alloy

    International Nuclear Information System (INIS)

    Mokhtarishirazabad, M.; Boutorabi, S.M.A.; Azadi, M.; Nikravan, M.

    2013-01-01

    This article investigates effects of adding rare earth elements (RE) into a magnesium–aluminum–zinc alloy (the AZ91 alloy) on its high cycle fatigue (HCF) behavior. For this purpose, AZ91 and AZ91+1% RE (AZE911) alloys were gravity casted in a metallic die. RE elements were added to the AZ91 alloy in the form of mischmetals. Microscopic evaluations with the scanning electron microscopy (SEM) and mechanical tests include tensile, hardness and HCF behaviors, were performed on prepared samples. Rotary bending fatigue tests were carried out at a stress ratio (R) of −1 and a frequency of 125 Hz, at the room temperature, in the air. The microscopic investigation demonstrates that the addition of 1% RE elements leads to the formation of Al 11 RE 3 intermetallic particles which is associated to the reduction of β-(Mg 17 Al 12 ) phases. Results of mechanical experiments suggest a negligible effect of adding 1% RE elements on mechanical properties of the AZ91 alloy. Curves of stress-life (S–N) shows an increase in the fatigue strength at 10 5 cycles, from 100±10 MPa to 135±10 MPa, when RE elements were added to the AZ91 alloy

  12. Effect of rare earth elements on high cycle fatigue behavior of AZ91 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtarishirazabad, M., E-mail: mehdi-mokhtari@hotmail.com [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Boutorabi, S.M.A. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Azadi, M.; Nikravan, M. [Irankhodro Powertrain Company (IPCO), Tehran (Iran, Islamic Republic of)

    2013-12-10

    This article investigates effects of adding rare earth elements (RE) into a magnesium–aluminum–zinc alloy (the AZ91 alloy) on its high cycle fatigue (HCF) behavior. For this purpose, AZ91 and AZ91+1% RE (AZE911) alloys were gravity casted in a metallic die. RE elements were added to the AZ91 alloy in the form of mischmetals. Microscopic evaluations with the scanning electron microscopy (SEM) and mechanical tests include tensile, hardness and HCF behaviors, were performed on prepared samples. Rotary bending fatigue tests were carried out at a stress ratio (R) of −1 and a frequency of 125 Hz, at the room temperature, in the air. The microscopic investigation demonstrates that the addition of 1% RE elements leads to the formation of Al{sub 11}RE{sub 3} intermetallic particles which is associated to the reduction of β-(Mg{sub 17}Al{sub 12}) phases. Results of mechanical experiments suggest a negligible effect of adding 1% RE elements on mechanical properties of the AZ91 alloy. Curves of stress-life (S–N) shows an increase in the fatigue strength at 10{sup 5} cycles, from 100±10 MPa to 135±10 MPa, when RE elements were added to the AZ91 alloy.

  13. Structural and magnetic order of ThMn12-type rare earth-iron-aluminium intermetallics studied by neutron diffraction

    International Nuclear Information System (INIS)

    Schaefer, W.; Halevy, I.; Gal, J.

    2000-01-01

    neutron powder diffraction data of ThMn 12 -type compounds RFe 4 Al 8 , RFe 5 Al 7 , and RFe 6 Al 6 (R = heavy rare earth) are compared to work out the structural variations and the different magnetic properties of these ternary intermetallics as a function of increasing iron concentrations. The variations of unit cell metric, of atomic coordinations and of interatomic distances are discussed. A magnetic phase diagram is presented showing the increase of the magnetic ordering temperatures from 120 K to 340 K and the change of the magnetic order from two separate magnetic phase transitions of rare earth and iron sublattices to one common ferrimagnetic transition of both sublattices, when changing the ratio of Fe/Al atoms from 4/8 to 6/6, respectively. Long range order is hampered by frozen spins. Magnetically ordered rare earth and iron moments are given. (orig.)

  14. Magnetic field strength dependence of the magnetostriction of rare-earth iron garnets

    International Nuclear Information System (INIS)

    Zvezdin, A.K.; Levitin, R.Z.; Popov, A.I.; Silant'ev, V.I.

    1981-01-01

    The magnetostriction of holmium-yttrium iron garnets Hosub(x)Ysub(3-x)Fesub(5)Osub(12) (x=3 or 1.05) is measured in pulsed magnetic fields up to 200 kOe at 78 K. It is shown that the magnetostriction constants lambda 111 and lambda 100 of these ferrimagnets depends on the magnetic field strength. The magnetostriction constant of the iron garnet Ho 3 Fe 5 O 12 increases and of the iron garnet Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) decreases with increase of the field strength. The field dependences of the anisotropic magnetostriction constants lambda 111 and lambda 100 for Hosub(1.05)Ysub(1.95)Fesub(5)Osub(12) are fundamentally different. Thus lambda 111 depends quadratically on the total effective field Hsub(eff) whereas lambda 100 depends almost linearly on Hsub(eff). A theoretical analysis of the magneto-elastic interaction in rare-earth iron garnets is carried out [ru

  15. Contribution to the study of magnetic properties of rare-earth iron intermetallic compounds

    International Nuclear Information System (INIS)

    Morariu, M.

    1976-01-01

    The intermetallic binary compounds Ysub(x)Fesub(y)(YFe 2 ,YFe 3 ,Y 6 Fe 23 ,Y 2 Fe 17 ), RFe 2 (R=Gd,Tb,Dy,Ho,Er and Tm) and the intermetallic pseudobinary compounds (Gdsub(x)Ysub(1-x))Fe 2 and Dy(Fesub(x)Nisub(1-x)) 3 were studied, using magnetic measurements and Moessbauer spectroscopy, in order to obtain information on their magnetic behaviour. The different models which describe magnetic interactions in rare-earths with 3d transition element compounds are reviewed. The magnetic hyperfine field Hsub(n) at the Fe 57 nucleus, measured by Moessbauer spectroscopy, depends on the atom position in the lattice, being sensitive to magnetic interactions with neighbouring atoms. The mean value of the magnetic hyperfine field, average Hsub(n) is proportional to the mean magnetic moment of the iron atom: average Hsub(n)/average μsub(Fe) approximately 150 kOe. The comparative study of the temperature dependence of average Hsub(n) and average μsub(Fe) values shows that this relation is valid for the whole range of magnetic ordering (T>Tsub(c)). The mean magnetic hyperfine fields at the Fe 57 nucleus in RFe 2 compounds depend on the rare-earth partner and vary approximative linearly with the Gennes factor. The spin reorientation diagram for the (Gdsub(x)Ysub(1-x))Fe 2 system is obtained. All results on Moessbauer spectroscopy are in good agreement with the magnetic measurements. The magnetic behaviour of iron atoms is justified using a model in which the most electrons are in a narrow band, so they could be considered localized, and the magnetic interactions between these atoms take place through a fraction (<5%) of 3d itinerant electrons. (author)

  16. Study on isothermal precision forging process of rare earth intensifying magnesium alloy

    International Nuclear Information System (INIS)

    Shan, Debin; Xu, Wenchen; Han, Xiuzhu; Huang, Xiaolei

    2012-01-01

    A three dimensional rigid-plastic finite element model is established to simulate the isothermal precision forging process of the magnesium alloy bracket based on DEFORM 3D in order to analyze the material flow rule and determine the forging process scheme. Some problems such as underfilling and too large forging pressure are predicted and resolved through optimizing the shapes of the billet successfully. Compared to the initial microstructure, the isothermal-forged microstructure of the alloy refines obviously and amounts of secondary phases precipitate on the matrix during isothermal forging process. In subsequent ageing process, large quantities of secondary phases precipitate from α-Mg matrix with increasing ageing time. The optimal comprehensive mechanical properties of the alloy have been obtained after aged at 473 K, 63 h with the ultimate tensile strength, tensile yield strength and elongation 380 MPa, 243 MPa and 4.07% respectively, which shows good potential for application of isothermal forging process of rare earth intensifying magnesium alloy.

  17. Microstructural characterisation of Al-Si cast alloys containing rare earth additions

    Science.gov (United States)

    Elgallad, E. M.; Ibrahim, M. F.; Doty, H. W.; Samuel, F. H.

    2018-05-01

    This paper presents a thorough study on the effect of rare earth elements, specifically La and Ce, on the microstructure characteristics of non-modified and Sr-modified A356 and A413 alloys. Several alloys were prepared by adding 1% La and 1% Ce either individually or in combination. Microstructural characterisation was carried out using optical microscopy, scanning electron microscopy and electron probe microanalysis as well as differential scanning calorimetry (DSC) analysis. The results showed that the individual and combined additions of La and Ce did not bring about any modification or even refinement in the eutectic Si structure. Moreover, these additions were found to negate the modification effect of Sr, particularly in the presence of La. The A356 and A413 alloys containing La and/or Ce displayed high phase volume fractions owing to the formation of Al-Si-La/Ce/(La,Ce) and Al-Ti-La/Ce intermetallic phases. DSC analysis revealed that the formation temperatures of these phases varied from 560 to 568 °C and 568 to 574 °C, respectively. This analysis also showed that the addition of La and Ce whether individually or in combination resulted in a depression in the eutectic temperature and a considerable increase in the solidification range, particularly for the A413 alloy.

  18. Ultrafast demagnetization in rare-earth alloys: the role of spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Le Guyader, Loic; Solopow, Sergej; Radu, Florin; Holldack, Karsten; Mitzner, Rolf; Kachel, Torsten; Pontius, Niko; Foehlisch, Alexander; Radu, Ilie [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Abrudan, Radu [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Institut fuer Experimentalphysik/Festkoerperphysik, Ruhr-Universitaet Bochum (Germany)

    2015-07-01

    Understanding the ultrafast demagnetization occurring upon femtosecond laser excitation of a magnetic material is a fundamental problem of modern magnetism and its microscopic origin remains highly elusive and intensely debated. Particularly, the spin-orbit coupling mediating the spin-lattice interaction is one of the key ingredients. An intriguing case of tunable parallel to anti-parallel LS coupling can be realized in rare-earth (RE) alloys. For instance, Gd60Sm40 and Gd60Dy40 alloys have similar absolute S and L, but exhibit opposite LS coupling while displaying the same ferromagnetic ordering temperature of 250 K. They constitute thus an ideal case to investigate the particular role of the LS coupling on the ultrafast demagnetization. Here we report on the properties of such RE thin film alloys using X-ray Magnetic Circular Dichroism (XMCD) with the spin and orbit sum rules at M5,4 edges. Femtosecond time-resolved transmission XMCD measurements performed at the slicing beamline reveal the element-specific demagnetization time constant in these alloys. Funding from European Union through FEMTOSPIN is gratefully acknowledged.

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

    International Nuclear Information System (INIS)

    Vassiliev, V.P.; Benaissa, Ablazeze; Taldrik, A.F.

    2013-01-01

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

  20. Grain Refinement and Enhancement of Mechanical Properties of Hot Extruded Rare-Earth Containing Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Bita Pourbahari

    2017-12-01

    Full Text Available The effects of rare earth addition and hot extrusion process on the grain refinement of magnesium alloy were studied. The as-cast Mg-6Al-1Zn (AZ61 alloy had the average grain size of ~ 64 µm and its microstructure consisted of α-Mg and Mg17Al12 phase. By partial substitution of Al with Gd to reach Mg-4.8Gd-1.2Al-1Zn alloy, it was observed that the Mg17Al12 phase disappeared and two new intermetallic phases, i.e. (Mg,Al3Gd and Al2Gd, were identified. The extrusion process showed significant effects on the shape and size of intermetallics and grain size of the matrix. The grain size of the extruded Mg-6Al-1Zn alloy was refined from 64 µm to 13.4 µm as a result of recrystallization. Regarding the Mg-4.8Gd-1.2Al-1Zn alloy, the grain refinement was much more pronounced, where the extruded grain size has been refined from 698 µm to 2.4 µm (extruded at 385 °C and 1.3 µm (extruded at 320 °C. This was related to the presence of fine and widely dispersed intermetallic phases. Tensile strength and total elongation of extruded alloys were much higher than their as-cast counterparts and the extruded Mg-6Zn-1Al alloy showed magnificent mechanical properties. The latter was related to the absence of intermetallic particles, which act as stress risers.

  1. The Effects of Grain Refinement and Rare Earth Intermetallics on Mechanical Properties of As-Cast and Wrought Magnesium Alloys

    Science.gov (United States)

    Pourbahari, Bita; Mirzadeh, Hamed; Emamy, Massoud

    2018-03-01

    The effects of rare earth intermetallics and grain refinement by alloying and hot extrusion on the mechanical properties of Mg-Gd-Al-Zn alloys have been studied to elucidate some useful ways to enhance the mechanical properties of magnesium alloys. It was revealed that aluminum as an alloying element is a much better grain refining agent compared with gadolinium, but the simultaneous presence of Al and Gd can refine the as-cast grain size more efficiently. The presence of fine and widely dispersed rare earth intermetallics was found to be favorable to achieve finer recrystallized grains during hot deformation by extrusion. The presence of coarse dendritic structure in the GZ61 alloy, grain boundary eutectic containing Mg17Al12 phase in the AZ61 alloy, and rare earth intermetallics with unfavorable morphology in the Mg-4Gd-2Al-1Zn alloy was found to be detrimental to mechanical properties of the alloy in the as-cast condition. As a result, the microstructural refinement induced by hot extrusion process resulted in a significant enhancement in strength and ductility of the alloys. The presence of intermetallic compounds in the extruded Mg-4Gd-2Al-1Zn and Mg-2Gd-4Al-1Zn alloys deteriorated tensile properties, which was related to the fact that such intermetallic compounds act as stress risers and microvoid initiation sites.

  2. Oxidation performance of a Fe-13Cr alloy with additions of rare earth elements

    International Nuclear Information System (INIS)

    Martinez-Villafane, A.; Chacon-Nava, J.G.; Gaona-Tiburcio, C.; Almeraya-Calderon, F.; Dominguez-Patino, G.; Gonzalez-Rodriguez, J.G.

    2003-01-01

    The influence of rare earth elements (REE's) i.e. Neodymium (Nd) and Praseodymium (Pr) on the oxidation behavior of a Fe-13Cr alloy has been studied, and its role on the oxidation rate and oxide morphology and formation is discussed. Specimens were isothermally oxidized in oxygen at 800 deg. C for 24 h. It was found that a small addition (≤0.03 wt.%) of either Nd or Pr, reduced the oxidation rate of the Fe-13Cr base alloy. Moreover, the simultaneous addition of both elements to the alloy produced a dramatic reduction in the oxidation kinetics. Analysis by scanning electronic microscope (SEM) revealed that the morphology of oxides formed on Fe-13Cr specimens with and without REE's specimens was very different. In fact, a fine-grained oxide morphology was observed for alloys with REE's addition. For these alloys only, chromium enrichment at the metal/scale interface was observed. From transmission electronic microscope (TEM) analysis, it was found the following: at the early stages of oxide formation, after 0.25 h, Cr 2 O 3 , Fe 3 O 4 , α-Fe 2 O 3 and γ-Fe 2 O 3 were formed; at 6 h, Cr 2 O 3 , FeCr 2 O 4 and α-Fe 2 O 3 were identified and, for exposure times greater than 6 h, Cr 2 O 3 , α-Fe 2 O 3 and a spinel which was presumably transformed into a solid solution (Fe 2 O 3 ·Cr 2 O 3 ) were found

  3. Proceedings of the sixth international workshop on rare earth-cobalt permanent magnets and their applications, August 31 - September 2, 1982, and third international symposium on magnetic anisotropy and coercivity in rare earth-transition metal alloys, September 3, 1982

    International Nuclear Information System (INIS)

    Fidler, J.

    1982-01-01

    The first part (workshop) is concerned specifically with applications of rare earth-cobalt permanent magnets. The session headings are 1) electro-mechanical applications 2) electronic and miscellaneous applications 3) magneto-mechanical applications plus workshop on measurement methods 4) new materials and processes 5) industrial applications of REPM and future aspects. The second part (symposium) is concerned with physical properties of specific rare earth-transition metal alloys. (G.Q.)

  4. Influence of strain and polycrystalline ordering on magnetic properties of high moment rare earth metals and alloys

    International Nuclear Information System (INIS)

    Scheunert, G; Ward, C; Hendren, W R; Bowman, R M; Lapicki, A A; Hardeman, R; Mooney, M; Gubbins, M

    2014-01-01

    Despite being the most suitable candidates for solenoid pole pieces in state-of-the-art superconductor-based electromagnets, the intrinsic magnetic properties of heavy rare earth metals and their alloys have gained comparatively little attention. With the potential of integration in micro and nanoscale devices, thin films of Gd, Dy, Tb, DyGd and DyTb were plasma-sputtered and investigated for their in-plane magnetic properties, with an emphasis on magnetization versus temperature profiles. Based on crystal structure analysis of the polycrystalline rare earth films, which consist of a low magnetic moment fcc layer at the seed interface topped with a higher moment hcp layer, an experimental protocol is introduced which allows the direct magnetic analysis of the individual layers. In line with the general trend of heavy lanthanides, the saturation magnetization was found to drop with increasing unit cell size. In situ annealed rare earth films exceeded the saturation magnetization of a high-moment Fe 65 Co 35 reference film in the cryogenic temperature regime, proving their potential for pole piece applications; however as-deposited rare earth films were found completely unsuitable. In agreement with theoretical predictions, sufficiently strained crystal phases of Tb and Dy did not exhibit an incommensurate magnetic order, unlike their single-crystal counterparts which have a helical phase. DyGd and DyTb alloys followed the trends of the elemental rare earth metals in terms of crystal structure and magnetic properties. Inter-rare-earth alloys hence present a desirable blend of saturation magnetization and operating temperature. (paper)

  5. Rare earths

    International Nuclear Information System (INIS)

    1984-01-01

    The conference was held from September 12 to 13, 1984 in Jetrichovice, Czechoslovakia. The participants heard 16 papers of which 4 were inputted in INIS. These papers dealt with industrial separation processes of rare earths, the use of chemical methods of separation from the concentrate of apatite and bastnesite, the effect of the relative permittivity of solvents in the elution of rare earth elements from a cation exchanger, and the determination of the content of different rare earth elements using X-ray fluorescence analysis and atomic absorption spectroscopy. (E.S.)

  6. Magnetic properties of exchange-coupled trilayers of amorphous rare-earth-cobalt alloys

    International Nuclear Information System (INIS)

    Wuechner, S.; Toussaint, J.C.; Voiron, J.

    1997-01-01

    From amorphous thin films from alloys of rare earths (Gd, Sm), yttrium or zirconium with cobalt we have prepared trilayers with very clean interfaces appropriate for the study of magnetic coupling. The sandwiches were typically Y-Co/Gd-Co/Y-Co and Sm-Co/X/Sm-Co ' (X=Gd-Co, Co-Zr, Co). The three individual layers are coupled magnetically by exchange interactions between cobalt moments throughout the entire sample. This coupling associated with the specific properties of the given alloy (magnetic moment, anisotropy, coercivity) leads to ferrimagnetic or ferromagnetic structures of the magnetization of adjacent layers and to novel magnetization processes. For systems consisting of magnetically hard external layers with different coercivities and a soft central layer (Sm-Co/X/Sm-Co ' , X=Gd-Co, Co-Zr), the influence of the central layer close-quote s thickness and type of the material on coupling and magnetization processes have been studied quantitatively. Numerical simulations using a one-dimensional model for describing the magnetization processes observed in sandwich systems fit the magnetization curves of these model systems particularly well. copyright 1997 The American Physical Society

  7. Effects of heat treatments on laser welded Mg-rare earth alloy NZ30K

    International Nuclear Information System (INIS)

    Dai Jun; Huang Jian; Li Min; Li Zhuguo; Dong Jie; Wu Yixiong

    2011-01-01

    Highlights: → Firstly find the tadpole-shape precipitates in the welding joint. → The precipitation strengthening can account for 79% of the total strength. → The results can provide some insights on the application of Mg-RE alloy. - Abstract: In this study, the effects of heat treatments on the quality of laser welded Mg-rare earth alloy NZ30K were systematically studied. The microstructure and mechanical properties of joints, welded by a 15 kW high power CO 2 laser, under different heat treatments had been tested and analyzed. The results indicated that the heat treatment plays an important role in the mechanical strength of laser welded joint of NZ30K. The microstructure of samples after the solution treatment as well as aging treatment is different from that of the as-received welded joint. For solution treatment, although the microstructure is much different from that of as-received welded joint, the solution strengthening effect is not obvious. There are lots of precipitates in the fusion zone after the aging treatment, which will significantly enhance the ultimate tensile strength (UTS) and the yield tensile strength (YTS) of the welding joint. 79% of YTS is caused by precipitation strengthening. Therefore, the results implied that the UTS and YTS can be greatly improved by proper heat treatment.

  8. X ray topographic study of defects and magnetic domains in rare earth iron garnets

    International Nuclear Information System (INIS)

    Mathiot, Alain.

    1975-11-01

    X ray topographs allow simultaneous observations of crystalline defects and magnetic domain walls (except 180 deg ones). The easy magnetization directions of rare earth iron garnets are and the equilibrium texture of (110) silices is limited by a rectangular array of 71 deg and 109 deg walls. Since the anisotropy and magnetostriction of the choosen compounds (TbIG and DyIG) increase sharply when the temperature is lowered, the influence of these parameters has been studied between 300K and 4.2K. Because of the increase of spontaneous magnetization and anisotropy, the domain number increases at low temperatures and the texture becomes less sensitive to the crystal imperfections. Besides the 109 deg walls disappear almost completely from the pattern; this has been shown to be due to the respective values of the wall energies, and particularly to the influence of the K 2 anisotropy constant. The contrasts observed on the topographs increase also sharply, because of the high values of the lambda 111 coefficient of spontaneous magnetostriction at low temperatures. A splitting of the Brugg reflection peak into two, below 60K for TbIG, each part corresponding to one family of domains, allowed a direct of lambda 111 . The garnets are materials chosen to study domain walls because of the large range of the anisotropy and magnetostriction values obtained in those compounds [fr

  9. Uranium, thorium and rare earth elements distribution from different iron quadrangle spring waters

    International Nuclear Information System (INIS)

    Ferreira, Cláudia A.; Palmieri, Helena E.L.; Menezes, Maria A. de B.C.; Rodrigues, Paulo C.H.

    2017-01-01

    This study was conducted to evaluate the concentrations of thorium, uranium and the rare earth elements (REE) in 26 spring waters, as well as the patterns of the REE of the samples from the Cercadinho, Moeda and Caue aquifers in different municipalities of the Iron Quadrangle (Quadrilatero Ferrifero), located in the central-southeast of Minas Gerais state. The pH value of the ground waters ranged from 3.8 to 7.0, indicating an acid nature of most of the spring waters. The investigation of REE speciation showed that all the REEs exist in the free X"3"+ ionic forms, under the prevailing Eh and pH conditions. In the studied samples the uranium concentrations ( 1000 ng L"-"1) originating from aquifers located in Sabara, Barao de Cocais, Santa Barbara, Mario Campos, Congonhas and Lavras Novas. The REEs patterns in the spring waters from the Cercadinho, Caue and Moeda aquifers are characterized by middle REE (MREE) enrichment compared to light REE (LREE) and heavy REEs (HREE), negative Ce anomalies (except for one sample) and positive Eu anomalies in all three aquifers studied. (author)

  10. Theory of Temperature Dependence of the Magnetization in Rare-Earth-Transition-Metal Alloys

    DEFF Research Database (Denmark)

    Szpunar, B.; Lindgård, Per-Anker

    1977-01-01

    -spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states. Es wird gezeigt, daß die Temperaturabhängigkeit der magnetischen Momente und die Curie-Temperatur sowie die Temperatur der ferrimagnetischen Kompensation für Gd1-xTx (T = Co, Ni und Fe) und Y......1-xCox durch ein einfaches Model1 erklärt werden können, das eine RKKY-Wechsel-wirkung zwischen den Momenten der Seltenen Erden und des Pseudo-Spins des Übergangsmetalls annimmt. Die Wechselwirkung wird durch ein effektives Legierungsmedium übermittelt, das mit der CPA-Theorie und elliptischen......It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures for Gdl-xTx (T = Co, Ni, and Fe) and Y1-xCox can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition-metal pseudo...

  11. Uranium, thorium and rare earth elements distribution from different iron quadrangle spring waters

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cláudia A.; Palmieri, Helena E.L.; Menezes, Maria A. de B.C.; Rodrigues, Paulo C.H., E-mail: cferreiraquimica@yahoo.com.br, E-mail: help@cdtn.br, E-mail: menezes@cdtn.br, E-mail: pchr@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-11-01

    This study was conducted to evaluate the concentrations of thorium, uranium and the rare earth elements (REE) in 26 spring waters, as well as the patterns of the REE of the samples from the Cercadinho, Moeda and Caue aquifers in different municipalities of the Iron Quadrangle (Quadrilatero Ferrifero), located in the central-southeast of Minas Gerais state. The pH value of the ground waters ranged from 3.8 to 7.0, indicating an acid nature of most of the spring waters. The investigation of REE speciation showed that all the REEs exist in the free X{sup 3+} ionic forms, under the prevailing Eh and pH conditions. In the studied samples the uranium concentrations (<2.3-1176 ng L{sup -1}) were below the guideline level set by Brazilian legislation (Ministry of Health 518- 03/2004). Thorium concentrations ranged from <0.39-11.0 ng L{sup -1} and the sum of the REE ranged from 6.0 to 37657 ng L{sup -1}. As there are no permissible limits related for the REE and thorium for different water quality standards in Brazil, more attention must be paid to the local residents' health risk caused by spring waters (REEs were > 1000 ng L{sup -1}) originating from aquifers located in Sabara, Barao de Cocais, Santa Barbara, Mario Campos, Congonhas and Lavras Novas. The REEs patterns in the spring waters from the Cercadinho, Caue and Moeda aquifers are characterized by middle REE (MREE) enrichment compared to light REE (LREE) and heavy REEs (HREE), negative Ce anomalies (except for one sample) and positive Eu anomalies in all three aquifers studied. (author)

  12. Methods of Separation of Total Rare Earths in Low-Alloy Constructional Steels

    Science.gov (United States)

    1954-11-10

    investigation of the effects of added anions upon the absorption spectra of the rare earths elements has been continued. The effects of tartrate in...complexes, the equilibrium among the di-hydrogen cupric EDTA complex, uncomplexed cupric ions, the monohydrogen rare earth- EDTA complex and rare...solutions used are described. A polaro- graphic method for determining cupric ion concentration in support- ing KNOj solutions, and thereby supporting

  13. Impression creep properties of a semi-solid processed magnesium-aluminum alloy containing calcium and rare earth elements

    International Nuclear Information System (INIS)

    Nami, B.; Razavi, H.; Miresmaeili, S.M.; Mirdamadi, Sh.; Shabestari, S.G.

    2011-01-01

    The creep properties of a thixoformed magnesium-aluminum alloy containing calcium and rare earth elements were studied under shear modulus-normalized stresses ranging from 0.0225 to 0.035 at temperatures of 150-212 o C using the impression creep technique. Analysis of the creep mechanism based on a power-law equation indicated that pipe diffusion-controlled dislocation climb is the dominant mechanism during creep. The alloy has a better creep resistance than high-pressure die-cast magnesium-aluminum alloy.

  14. Quantum Magnetism Applied to the Iron-Pnictides and Rare Earth Pyrochlores

    Science.gov (United States)

    Applegate, Ryan

    This dissertation presents computational studies of two families of magnetic materials of significant current interest. The iron pnictides are new high temperature superconductors with interesting parent compound antiferromagnetism. The rare earth pyrochlore material Yb2Ti2O7 is a candidate quantum spin ice. The magnetic and structural phases of individual iron pnictides have both many common features and material specific differences. In an attempt to unify these behaviors as instances of a larger theoretical picture, we use Monte Carlo simulations of a two-dimensional Hamiltonian with coupled Heisenberg-spin and Ising-orbital degrees of freedom. We introduce spin-space and single-ion anisotropies and study the finite temperature transitions in our model. We develop a phase diagram and propose that the interplay of spin and orbital physics in the presence of anisotropy could explain how material details affect the transitions of the pnictide materials. Nuclear magnetic resonance (NMR) can study magnetic materials via the hyperfine interaction and the coupling between the nuclear moment and the field produced by the samples local moment environment. Recent measurements suggest that Zn doped BaFe2As2 may have quantum fluctuations about the striped phase that produce a distribution of fields at As nuclear sites. The non-magnetic ion Zn replaces Fe and can be treated as an impurity which can be studied by a zero-temperature Ising Series expansion method. We propose a Heisenberg-like J1a-J 1b-J2 model which has small ferromagnetic exchanges along the b axis and strong antiferromagnetic exchanges along the a axis. In our impurity model we find that the magnetic moments are everywhere reduced by quantum fluctuations, except on the nearest neighbor site in the AFM direction. We suggest that the presented impurity model may provide an explanation for the experimental measurements. Based on a recently proposed quantum spin ice model, we use numerical linked cluster (NLC

  15. Analysis on three-sublattice model of magnetic properties in rare-earth iron garnets under high magnetic fields

    International Nuclear Information System (INIS)

    Wang Wei; Chen Ri; Qi Xin

    2012-01-01

    Highlights: ► An improved three-sublattice model is provided. ► The magnetic properties of the rare-earth ions show great importance to the magnetic behaviors of rare-earth iron garnets. ► The coefficients α i associated with λ and χ are the functions of H e and T. ► The changes of M with H e at different temperatures are revealed. - Abstract: In this paper, based on the molecular field theory, a new and improved three-sublattice model on studying the magnetic properties of ferrimagnetic rare-earth iron garnet in high magnetic fields is introduced. Here, the effective exchange field is described as H i = λM = λχH e , where λ is the coefficient associated with the molecular field, χ is the effective magnetic susceptibility, and H e is external magnetic fields. As is known, the magnetic sublattices in rare-earth iron garnets can be classified three kinds labeled as a, c and d, in our calculations, whose magnetizations are defined as M a , M c and M d , respectively. Then, using this model, the temperature and field dependences of the total magnetization in Dy 3 Fe 5 O 12 (DyIG) are discussed. Meanwhile, the magnetizations of the three kinds of magnetic sublattices are analyzed. Furthermore, our theory suggests that the coefficients α i associated with λ and χ in DyIG show obvious anisotropic, temperature-dependence and field-dependence characteristics. And, the theoretical calculations exactly fit the experimental data.

  16. Nested Fermi surfaces and order in the rare earth nickel borocarbides and copper palladium alloys

    International Nuclear Information System (INIS)

    Wilkinson, Ian

    2002-01-01

    The electronic structure of two systems, each displaying a different type of order believed to derive from their respective Fermi surface topologies, has been investigated using the two-dimensional angular correlation of annihilation radiation (2D-ACAR) technique. A particular topological feature of a generic rare earth nickel borocarbide (general formula RNi 2 B 2 C) Fermi surface is popularly believed to be responsible for a particular modulated arrangement of local moments observed in several magnetic borocarbides. Accordingly, c-axis 2D-ACAR spectra were collected from four representative members of the series, namely the Er, Tm, Yb and Lu compounds. A further a-axis projection from LuNi 2 B 2 C provides an additional comparison with electronic structure calculations performed for this compound. The c-axis projected k-space electron occupancies reveal a fundamentally similar Fermi surface topology across the measured compounds. The a- and c-axis k-space occupancies obtained from LuNi 2 B 2 C showed exceptional qualitative agreement with the corresponding calculated electron occupancy. A number of edge-detection methods were employed to identify the projected Fermi surface, and the existence of the proposed feature was confirmed by direct observation in each of the measured compounds. Calipers of this feature were found to be in good general agreement with those predicted by relevant calculation and expected from indirect experimental evidence. The compositional phase behaviour of copper-palladium solid solutions is believed to be strongly influenced by the shape of their respective Fermi surfaces. In particular, the concentration-dependent positions of diffuse peaks in electron and X-ray diffraction patterns from disordered samples has been associated with the corresponding evolution of flat, parallel areas on the alloy Fermi surface. Electronic structure calculations indicate these areas to be maximal around 40 at. % Pd, and it has been further suggested that

  17. Comment on contact contributions to the magnetic hyperfine interaction of rare-earth impurities in iron

    International Nuclear Information System (INIS)

    Bernas, H.

    1977-01-01

    The influence of the strong d character of the Fe conduction band on the hyperfine interaction of dilute rare earth impurities is emphasized, and the contact contributions are estimated. Apparent inconsistencies between hyperfine field measurements for Eu and Gd in Fe are noted

  18. The influences of rare earth content on the microstructure and mechanical properties of Mg-7Zn-5Al alloy

    International Nuclear Information System (INIS)

    Xiao, Wenlong; Shen, Yusen; Wang, Lidong; Wu, Yaoming; Cao, Zhanyi; Jia, Shusheng; Wang, Limin

    2010-01-01

    The influences of rare earth (RE) on the microstructure and mechanical properties of Mg-7Zn-5Al alloy were studied. The results indicate that both the dendrite and grain size of the alloy can be refined by low RE addition. The Al 2 REZn 2 phase will be formed with increasing the RE content, however the high RE addition results in the grain coarsening in the alloy due to the decrease of the contribution of Al and Zn solutes on the grain refinement. The strengthening and weakening mechanisms caused by RE addition only lead to the obviously improve on the room temperature ultimate tensile strength. The mechanical properties of the studied alloys can be improved by aging treatment, and the aged Mg-7Zn-5Al-2RE alloy exhibits optimal mechanical properties at room temperature.

  19. Anisotropy and Microstructure of High Coercivity Rare Earth Iron Permanent Magnets, List of Papers Published

    Science.gov (United States)

    1989-01-01

    hardly influences both the pared by three different production technologies, absolute value of HA and its temperature dependence. The permanent magnets...ing reverse domains [2]. pared from 99.5% pure cast material supplied by The application of these magnets has been Rare Earth Products. The...the c/ re 3b Fig.. E ncrographs showingthe celular precipitation structure of precipitation hardened SmCo 2:17 magnets (a). In low coercivity magnets

  20. Corrosion behavior of novel imitation-gold copper alloy with rare earth in 3.5% NaCl solution

    International Nuclear Information System (INIS)

    Chen, J.L.; Li, Z.; Zhu, A.Y.; Luo, L.Y.; Liang, J.

    2012-01-01

    Highlights: → The design alloy has better anti-tarnish property than that of H7211 alloy during salt-spray test. → The corrosion rate of design alloy is much lower than that of H7211 alloy as immersed in NaCl solution. → In the low frequency region, the capacitive behavior normally faded and diffusion process had a key role. → In the medium frequency region, the Bode pattern showed a capacitive behavior. -- Abstract: A novel imitation-gold copper alloy with rare earth was designed and prepared. The corrosion behavior of the alloy immersed in 3.5% NaCl solution and its anti-tarnish property in the salt spray for different days has been studied. The designed alloy (CuZnAlNiMeRe) has more excellent anti-tarnish property and lower corrosion rate than those of currency coinage materials of H7211 alloy (used in China). A uniform and compact of corrosion film has been formed after the designed alloy immersed in 3.5% NaCl solution. The corrosion current densities I corr of the alloy decreased while the polarization resistance R p increased with time. The capacitance of the corrosion product film C film of the alloy decreased while the charge transfer resistance R ct . The Warburg diffusion impedance W R and the resistance of the equivalent circuit R increased with time.

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

    Directory of Open Access Journals (Sweden)

    M. G. Mahmoud

    2017-01-01

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

  2. Rare earth elements in the banded iron formation of the Griqualand West sequence, northern Cape Province, South Africa

    International Nuclear Information System (INIS)

    Horstmann, U.E.; Haelbich, I.W.; Cornell, D.H.

    1990-01-01

    The Proterozoic banded iron-formations (BIF) of the Griqualand West sequence of the Transvaal Supergroup in the northern Cape Province of South Africa have been investigated for their rare earth elements (REE) contents. Twenty three REE analyses were completed using an ICP-AES method. Despite diagenetic and metamorphic processes, it can be concluded from the so far available REE data that the conspicuous differences in REE patterns to those reported from elsewhere indicate the BIF of the Transvaal Supergroup to have originated in relative restricted parts or basins of the Precambrian ocean. 7 refs., 1 fig

  3. The influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel

    Science.gov (United States)

    Chu, Rensheng; Mu, Shukun; Liu, Jingang; Li, Zhanjun

    2017-09-01

    In the current paper, it is analyzed for the influence of high heat input and inclusions control for rare earth on welding in low alloy high strength steel. It is observed for the structure for different heat input of the coarse-grained area. It is finest for the coarse grain with the high heat input of 200 kJ / cm and the coarse grain area with 400 kJ / cm is the largest. The performance with the heat input of 200 kJ / cm for -20 °C V-shaped notch oscillatory power is better than the heat input of 400 kJ / cm. The grain structure is the ferrite and bainite for different holding time. The grain structure for 5s holding time has a grain size of 82.9 μm with heat input of 200 kJ/cm and grain size of 97.9 μm for 10s holding time. For the inclusions for HSLA steel with adding rare earth, they are Al2O3-CaS inclusions in the Al2O3-CaS-CaO ternary phase diagram. At the same time, it can not be found for low melting calcium aluminate inclusions compared to the inclusions for the HSLA steel without rare earth. Most of the size for the inclusions is between 1 ~ 10μm. The overall grain structure is smaller and the welding performance is more excellent for adding rare earth.

  4. Rare earths and actinides

    International Nuclear Information System (INIS)

    Coqblin, B.

    1982-01-01

    This paper reviews the different properties of rare-earths and actinides, either as pure metals or as in alloys or compounds. Three different cases are considered: (i) First, in the case of 'normal' rare-earths which are characterized by a valence of 3, we discuss essentially the magnetic ordering, the coexistence between superconductivity and magnetism and the properties of amorphous rare-earth systems. (ii) Second, in the case of 'anomalous' rare-earths, we distinguish between either 'intermediate-valence' systems or 'Kondo' systems. Special emphasis is given to the problems of the 'Kondo lattice' (for compounds such as CeAl 2 ,CeAl 3 or CeB 6 ) or the 'Anderson lattice' (for compounds such as TmSe). The problem of neutron diffraction in these systems is also discussed. (iii) Third, in the case of actinides, we can separate between the d-f hybridized and almost magnetic metals at the beginning of the series and the rare-earth like the metals after americium. (orig.)

  5. ELECTRICAL PROPERTIES OF COMPOUNDS AND ALLOYS OF RARE-EARTH METALS WITH ELEMENTS OF GROUPS V AND VI

    Energy Technology Data Exchange (ETDEWEB)

    Reid, F. J.; Matson, L. K.; Miller, J. F.; Himes, R. C.

    1963-04-15

    The electric properties of rare earth compounds and alloys with As, Sb, Se, and Te are reported. Without exception, samples of Se and Te compounds with normally trivalent Nd, Gd, and Ce having synthetic compositions, MX and M/sub 3/X/ sub 4/, are n-type wrth free electron concentrations in the range 10/sup 20/ to 10 /sup 22//cm/sup 3/, and have very low electric resistivities. Room temperature electric properties and thermoelectric data are tabulated. (P.C H.)

  6. Improvement of corrosion resistance and biocompatibility of rare-earth WE43 magnesium alloy by neodymium self-ion implantation

    International Nuclear Information System (INIS)

    Jin, Weihong; Wu, Guosong; Feng, Hongqing; Wang, Wenhao; Zhang, Xuming; Chu, Paul K.

    2015-01-01

    Highlights: • Nd self-ion implantation produces a smooth and hydrophobic surface on rare-earth WE43 Mg alloy. • The implanted layer is composed of mainly Nd 2 O 3 and MgO. • Degradation is significantly retarded in simulated body fluids and cell culture medium. • The Nd-implanted WE43 alloy exhibits remarkably enhanced cell adhesion and biocompatibility. - Abstract: Without introducing extraneous elements, a small amount of Nd is introduced into rare-earth WE43 magnesium alloy by ion implantation. The surface composition, morphology, polarization, and electrochemical properties, as well as weight loss, pH, and leached ion concentrations after immersion, are systematically evaluated to determine the corrosion behavior. The cell adhesion and viability are also determined to evaluate the biological response in vitro. A relatively smooth and hydrophobic surface layer composed of mainly Nd 2 O 3 and MgO is produced and degradation of WE43 is significantly retarded. Furthermore, significantly enhanced cell adhesion and excellent biocompatibility are observed after Nd self-ion implantation

  7. Determination of rare earth elements in products of Chadormalu iron ore concentrator plant (Iran) from beneficiation point of view

    International Nuclear Information System (INIS)

    Jorjani, E.; Bagherieh, A. H.; Rezai, B.

    2007-01-01

    :Different samples have been prepared from different products in Chadormalu iron ore concentrator plant: Low intensity magnetite separators concentrate (magnetite concentrate), reverse flotation tail (final hematite concentrate), flotation concentrate (apatite concentrate), final tail (L.I. M.S. tail + reverse flotation concentrate + apatite flotation tail). The samples were used for rare earth elements (REEs) distribution and origin studies. The assay of REEs was determined by ICP-MS spectrometry. The amount of total (light and heavy) REEs were 9631, 291, 199, 2236 ppm and the distributions were 19.3, 3.6, 10.1, 67% in flotation concentrate (apatite concentrate), reverse flotation tail (hematite concentrate), magnetite concentrate and total tail respectively. About 19.3% of total REEs were distributed in apatite concentrate with an assay of 9631 ppm. Therefore, further studies have been conducted on this product. According to the Xray studies the minerals of fluoroapatite, ankerite and calcite are the main mineral phases in apatite concentrate which the apatite is dominant among them. The scanning electron microscopy studies were shown that the high amount of REEs distributed on fluoroapatite mineral. The results have clearly shown that the apatite concentrate that is a by product of iron dressing in Chadormalu plant, with a low economical value and left without any further treatment, can be used as a significant source of REEs. According to this characterization studies, the recovery of a mixed rare earth oxide from fluoroapatite is possible either with the treatment of liquors from the total dissolution of the ore in nitric acid or with the proposed treatment of the phosphogypsum by-product from the conventional sulphuric acid route and the recovery of rare earth oxides from phosphoric acid sludges that the detailed flowsheet needs further extraction work

  8. Exceptional increase in the creep life of magnesium rare-earth alloys due to localized bond stiffening.

    Science.gov (United States)

    Choudhuri, Deep; Srinivasan, Srivilliputhur G; Gibson, Mark A; Zheng, Yufeng; Jaeger, David L; Fraser, Hamish L; Banerjee, Rajarshi

    2017-12-08

    Several recent papers report spectacular, and unexpected, order of magnitude improvement in creep life of alloys upon adding small amounts of elements like zinc. This microalloying effect raises fundamental questions regarding creep deformation mechanisms. Here, using atomic-scale characterization and first principles calculations, we attribute the 600% increase in creep life in a prototypical Mg-rare earth (RE)-Zn alloy to multiple mechanisms caused by RE-Zn bonding-stabilization of a large volume fraction of strengthening precipitates on slip planes, increase in vacancy diffusion barrier, reduction in activated cross-slip, and enhancement of covalent character and bond strength around Zn solutes along the c-axis of Mg. We report that increased vacancy diffusion barrier, which correlates with the observed 25% increase in interplanar bond stiffness, primarily enhances the high-temperature creep life. Thus, we demonstrate that an approach of local, randomized tailoring of bond stiffness via microalloying enhances creep performance of alloys.

  9. Strain-controlled low cycle fatigue properties of a rare-earth containing ME20 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mirza, F.A., E-mail: f4mirza@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Wang, K.; Bhole, S.D.; Friedman, J.; Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Ni, D.R.; Xiao, B.L. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Ma, Z.Y., E-mail: zyma@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-04-20

    The present study was aimed to evaluate the strain-controlled cyclic deformation characteristics and low cycle fatigue (LCF) life of a low (~0.3 wt%) Ce-containing ME20-H112 magnesium alloy. The alloy contained equiaxed grains with ellipsoidal particles containing Mg and Ce (Mg{sub 12}Ce), and exhibited a relatively weak basal texture. Unlike the high rare earth (RE)-containing magnesium alloy, the ME20M-H112 alloy exhibited asymmetrical hysteresis loops somewhat similar to the RE-free extruded Mg alloys due to the presence of twinning-detwinning activities during cyclic deformation. While cyclic stabilization was barely achieved even at the lower strain amplitudes, cyclic softening was the predominant characteristics at most strain amplitudes. The ME20M-H112 alloy showed basically an equivalent fatigue life to that of the RE-free extruded Mg alloys, which could be described by the Coffin-Manson law and Basquin's equation. Fatigue crack was observed to initiate from the near-surface imperfections, and in contrast to the typical fatigue striations, the present alloy showed some shallow dimples along with some fractions of quasi-cleavage features in the crack propagation area.

  10. Rare-Earth-Rich Alloys; Alliages a Teneur Elevee en Terres Rares; Splavy, obogashchennye redkozemel'nymi ehlementami; Aleaciones Ricas en Tierras Raras

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, M.; Kato, H. [Albany Metallurgy Research Center, Bureau of Mines, United States Department of the Interior, Albany, OR (United States)

    1964-06-15

    The rare earth metals with high thermal-neutron capture cross-sections are of interest for control of power-producing reactors; however, they are susceptible to corrosion. On the premise that non-rare earth metals may be alloyed with dysprosium, erbium, gadolinium and samarium, thus improving their properties, the effects of selected alloying additions on the rare earths were studied. The solubilities of the non-rare earth metals, zirconium, vanadium, chromium, iron, nickel, copper, aluminium and silicon, in dysprosium, erbium, gadolinium and samarium and their effects on the melting points, solid state transformations and corrosion properties were studied. -Phase diagrams were prepared up to the first rare earth-rich compound or eutectic, whichever occurred first. On completion of that portion of the work, alloys were made, heat-treated to yield maximum solid solubility of the non-rare earth alloying addition, and oxidation- and corrosion-tested. No improvement of the rare earth metals to oxidation resistance in the atmosphere was observed on alloying; in fact, most additions proved to be deleterious. Aluminium greatly improved the hot-Water corrosion resistance of the rare earths tested; other non-rare earth metal additions improved the resistance to a lesser degree. (author) [French] Les terres rares possedent une section efficace de capture des neutrons thermiques elevee; ces metaux presentent un grand interet pour le controle des reacteurs de puissance; toutefois, ils sont attaques par corrosion. En.partant de l'idee qu'il est possible d'allier des metaux autres que les terres rares avec le dysprosium, l 'erbium, le gadolinium et le samarium, et d'ameliorer ainsi leurs proprietes, les auteurs .ont observe les effets de l 'addition de certains metaux sur les terres rares. Ils ont etudie les solubilites du zirconium, du vanadium, du chrome; du fer, du nickel, du cuivre, de l'aluminium et du silicium dans le dysprosium, l'erbium, le gadolinium et le samarium

  11. Influence of rare earth oxides in the oxidation of chromia forming alloys

    International Nuclear Information System (INIS)

    Ramanathan, L.V.

    1989-01-01

    The influence of superficial application of rare earth oxides such as CeO sub(2), La sub(2)O sub(3), Nd sub(2)O sub(3), Sm sub(2)O sub(3), and Gd sub(2)O sub (3) to AISI 304 and 310 stainless steels, on their isothermal oxidation behavior at 900 sup(0) and 1000 sup(0)C, and cyclic oxidation behavior between 20 sup(0) and 1000 sup(0)C has been studied. The application of rare earth oxides (REO) has been found to increase the oxidation resistance at AISI 304. No significant improvements in oxidation resistance of AISI 310 were noted. The oxidation resistance of AISI 304 was highest in the presence of CeO sub(2) on its surface. The other REO in decreasing order of influence on oxidation resistance are La sub(2)O sub(3), Nd sub(2)O sub(3), Sm sub(2)O sub(3) and Gd sub(2)O sub(3). SEM investigations of the oxide scale morphology revealed that the improved resistance is probably due to the formation of a thin layer of fine grained compact Cr sub(2)O sub(3) and the higher adhesion of the scale to its increased plasticity. (author)

  12. Application of unsupervised pattern recognition approaches for exploration of rare earth elements in Se-Chahun iron ore, central Iran

    Science.gov (United States)

    Sarparandeh, Mohammadali; Hezarkhani, Ardeshir

    2017-12-01

    The use of efficient methods for data processing has always been of interest to researchers in the field of earth sciences. Pattern recognition techniques are appropriate methods for high-dimensional data such as geochemical data. Evaluation of the geochemical distribution of rare earth elements (REEs) requires the use of such methods. In particular, the multivariate nature of REE data makes them a good target for numerical analysis. The main subject of this paper is application of unsupervised pattern recognition approaches in evaluating geochemical distribution of REEs in the Kiruna type magnetite-apatite deposit of Se-Chahun. For this purpose, 42 bulk lithology samples were collected from the Se-Chahun iron ore deposit. In this study, 14 rare earth elements were measured with inductively coupled plasma mass spectrometry (ICP-MS). Pattern recognition makes it possible to evaluate the relations between the samples based on all these 14 features, simultaneously. In addition to providing easy solutions, discovery of the hidden information and relations of data samples is the advantage of these methods. Therefore, four clustering methods (unsupervised pattern recognition) - including a modified basic sequential algorithmic scheme (MBSAS), hierarchical (agglomerative) clustering, k-means clustering and self-organizing map (SOM) - were applied and results were evaluated using the silhouette criterion. Samples were clustered in four types. Finally, the results of this study were validated with geological facts and analysis results from, for example, scanning electron microscopy (SEM), X-ray diffraction (XRD), ICP-MS and optical mineralogy. The results of the k-means clustering and SOM methods have the best matches with reality, with experimental studies of samples and with field surveys. Since only the rare earth elements are used in this division, a good agreement of the results with lithology is considerable. It is concluded that the combination of the proposed

  13. Effect of rare earth elements yttrium and lanthanum on high temperature oxidation resistance of Mo-Si-B alloys

    International Nuclear Information System (INIS)

    Majumdar, Sanjib

    2014-01-01

    In the present investigation, 0.2 to 2 at% Y and La alloyed Mo-9Si-8B were consolidated using mechanical alloying followed by spark plasma sintering. Isothermal oxidation studies were conducted in a wide temperature range from 650 to 1300℃. Detailed characterization studies of the oxide scale using SEM, EDS, FIB, TEM reveal the formation of Y x Mo 18 O 32 and 3La 2 O 3 ·MoO 3 oxide phases, respectively, for Y and La-containing alloys reduce the evaporation of MoO 3 . The growth rate of protective silica scale is also enhanced due to faster formation of Y and La rich oxide particles which probably act as nucleation sites for silica. At higher temperatures (at 1100℃), the oxidation behavior of unalloyed and RE-alloyed Mo-9Si-8B are comparable. A transient weight loss followed by a steady state is reached due to protective amorphous silica-rich scale formation beyond 1100℃. Therefore, alloying with rare earth elements provides a broader application temperature window for silicide based materials starting from 750℃ to 1300℃

  14. Rare earths: occurrence, production and applications

    International Nuclear Information System (INIS)

    Murthy, T.K.S.; Mukherjee, T.K.

    2002-01-01

    The mining and processing of rare earth minerals, particularly of monazite, began in a modest way in 1880s for commercialized production of mantle for gas lighting. For all major applications up to mid-twentieth century- production of lighter flints, misch metal as a metallurgical alloying agent, colouring, decolourizing and polishing agents for glass, petroleum cracking catalysts and arc-carbons, unseparated or partially separated rare earths were adequate. These applications continue till today. With the development and industrial application of powerful techniques like ion exchange and solvent extraction for the separation of rare earths, the decades after 1960 saw increasing utilization of the specific properties of the individual rare earths. Some of these advanced technological applications include: special glass for optical systems including camera lenses, phosphors for colour television, cathode ray tubes and fluorescent lighting, X-ray intensification screens, high intensity permanent magnets, electro optical devices, lasers, hydrogen storage materials, hydride rechargeable batteries, photomagnetic data storage systems, autoexhaust catalysts, special ceramics of unusual toughness, artificial diamonds and nonpoisonous plastic colorants. The topics covered in the book include rare earths: their story identity, rare earth resources, processing of ores and recovery of mixed rare earths products, separation and purification of rare earths, nonmetallic applications of rare earths, rare earth metals: production and applications, rare earth alloys and their applications, analysis of rare earth, processing of rare earth resources in India by Indian Rare Earth Ltd. and availability and market conditions

  15. Effect of Solidification Rate and Rare Earth Metal Addition on the Microstructural Characteristics and Porosity Formation in A356 Alloy

    Directory of Open Access Journals (Sweden)

    M. G. Mahmoud

    2017-01-01

    Full Text Available The present study was performed on A356 alloy with the main aim of investigating the effects of La and Ce additions to 356 alloys (with and without 100 ppm Sr on the microstructure and porosity formation in these alloys. Measured amounts of La, Ce, and Sr were added to the molten alloy. The results showed that, in the absence of Sr, addition of La and Ce leads to an increase in the nucleation temperature of the α-Al dendritic network with a decrease in the temperature of the eutectic Si precipitation, resulting in increasing the freezing range. Addition of 100 ppm Sr results in neutralizing these effects. The presence of La or Ce in the casting has a minor effect on eutectic Si modification, in spite of the observed depression in the eutectic temperature. It should be noted that Ce is more effective than La as an alternate modifying agent. According to the atomic radius ratio, rLa/rSi is 1.604 and rCe/rSi is 1.559, theoretically, which shows that Ce is relatively more effective than La. The present findings confirm that Sr is the most dominating modification agent. Interaction between rare earth (RE metals and Sr would reduce the effectiveness of Sr. Although modification with Sr causes the formation of shrinkage porosity, it also reacts with RE-rich intermetallics, resulting in their fragmentation.

  16. Synthesis and magnetic properties of rare-earth free MnBi alloy: A high-energy hard magnetic material

    Science.gov (United States)

    Sharma, Sanjeev Kumar; Prakash, H. R.; Ram, S.; Pradhan, D.

    2018-04-01

    MnBi is a rare-earth free high-energy magnetic material useful for the permanent magnet based devices. In a simple method, a MnBi alloy was prepared by arc melting method using Mn and Bi metals in 60:40 atomic ratio. In terms of the X-ray diffraction, a crystalline MnBi phase is formed with Bi as impurity phase of the as-prepared alloy. FESEM image of chemically etched sample shows small grains throughout the alloy. SEAD pattern and lattice image were studied to understand the internal microstructure of the alloy. The thermomagnetic curves measured in ZFC-FC cycles over 5-380 K temperatures at 500 Oe field, shows the induced magnetization of 5-25 % in the sample. The coercivity values, 7.455 kOe (13.07 emu/g magnetization) at 380 K, and 5.185k Oe (14.75 emu/g magnetization) at 300 K, are observed in the M-H hysteresis loops. A decreased value 0.181kOe (18.05 emu/g magnetization) appears at 100 K due to the change in the magnetocrystalline anisotropy. The results are useful to fabricate small MnBi magnets for different permanent magnets based devices.

  17. THE EFFECT OF RARE EARTH ELEMENTS ON Cr PRECIPITATIONS IN A Cu-0.8WT%Cr ALLOY

    Directory of Open Access Journals (Sweden)

    Gewang Shuai

    2011-05-01

    Full Text Available The microstructural evolution of Cu-based alloys during aging was studied using a quantitative metallographic method. Samples were cut from ingots of Cu-0.8wt%Cr and Cu-0.8wt%Cr-RE alloys. These were solution treated at 1000 ºC for 1.5h and subsequently quenched in water, then separately aged at 480 ºC for different durations. The microstructures were observed by optical microscope, and the characteristic geometric parameters of precipitated Cr phase, including volume fraction VV, face density NA, mean diameter and roundness, were measured. These data provided more details about the process of aging. The results showed that precipitation of Cr phase occurred in the form of particles during aging. Rare earth elements promoted the precipitation of Cr phase and dispersed Cr particles. The phenomenon of overaging came earlier in Cu-Cr-RE than in Cu-Cr. In the present work, the optimal aging time at 480 ºC was 2 hrs for the Cu-0.8wt%Cr-RE alloy and 3 hours for the Cu-0.8wt%Cr alloy.

  18. Rare earths 1998 market update

    International Nuclear Information System (INIS)

    Tourre, J.M.

    1998-01-01

    The rare earth industry has always been a world of rapid change with the emergence of new markets, new ores and new players, as well as the disappearance of old applications. Rare earth based products are used in a great diversity of applications such as hard disk drives, CD drives, batteries, capacitors, pigments, ceramics, polishing powders, fuel cells, flints, catalyst converter, fluid cracking catalysts, etc. South East Asia holds the largest share of the known reserve of rare earth ores and is one of the major markets for rare earth compounds; in the last ten years, China has become the largest producer of rare earth intermediates as well as an important exporter of separated rare earth elements. Today, China has approximately 150 factories producing rare earth compounds, most of which are experiencing financial difficulties due to the lack of knowledge of true market needs, lack of control of their distribution channels and production over-capacity. Recently the Chinese rare earth producers have recognized the situation and efforts are underway to rationalize rare earth production. Japan has dominated many of the major application markets, and is by far the largest market for metal and alloy products. This will remain the case for the next five years; however, new countries are emerging as significant users of rare earth products such as Korea, Taiwan and Malaysia. During the last ten years rare earth producers adjusted to several radical changes that affected the raw materials, the application mix and the price structure. New producers have emerged, especially from China; some have subsequently stopped their activities while others have focused their efforts in a specific market segment

  19. Effect of rare earth Ce on the far infrared radiation property of iron ore tailings ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Meng, Junping, E-mail: srlj158@sina.com [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Liang, Jinsheng; Duan, Xinhui [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Huo, Xiaoli [Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China); Tang, Qingguo [Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education, Tianjin 300130 (China); Institute of Power Source and Ecomaterials Science, Hebei University of Technology, Tianjin 300130 (China)

    2015-06-15

    Highlights: • Detailed process proposed for preparation of iron ore tailings ceramics. • Replace natural minerals with iron ore tailings as raw materials for preparing functional ceramics. • Impact mechanism of Ce on far infrared ceramics, as well as its optimum addition amounts can be obtained. • Propose a new perspective on considering the mechanism of far infrared radiation. - Abstract: A kind of far infrared radiation ceramics was prepared by using iron ore tailings, CaCO{sub 3} and SiO{sub 2} as main raw materials, and Ce as additive. The result of Fourier transform infrared spectroscopy showed that the sample exhibits excellent radiation value of 0.914 when doping 7 wt.% Ce. Ce{sup 4+} dissolved into iron diopside and formed interstitial solid solution with it sintered at 1150 °C. The oxidation of Fe{sup 2+} to Fe{sup 3+} caused by Ce{sup 4+} led to a decrease of crystallite sizes and enhancement of Mg–O and Fe–O vibration in iron diopside, which consequently improved the far infrared radiation properties of iron ore tailings ceramics.

  20. Constitution, structure and magnetic properties of some rare-earth - cobalt-aluminium alloys

    International Nuclear Information System (INIS)

    Evans, J.; Harris, I.R.

    1982-01-01

    The constitution and structure of the alloys represented by the formulae Cesub(1-x)Alsub(x)Co 5 and Prsub(1-x)Alsub(x)Co 5 (where 0 = 5 produces a mixture of the 1:5 and 2:17 phases based on CeCo 5 and Ce 2 Co 17 ; there are two variations of the 2:17 phase which are isostructural with the hexagonal Th 2 Ni 17 -type and rhombohedral Th 2 Zn 17 -type phases. At the composition Cesub(0.76)Alsub(0.24)Co 5 (4 at % Al) the alloy consists only of the 2:17-type phases and metallographically the alloy is one phase in appearance. Further substitution of Al results in the precipitation of an fcc phase, based on the Co-Al solid solution, in the 2:17 matrix. The crystal structures of the Prsub(1-x)Alsub(x)Co 5 alloys are very similar to those of the equivalent cerium alloys. The metallographic structures of the Pr alloys in the composition range 1 to 3 at % Al show significant differences from the corresponding Ce alloys. Determination of the Curie temperatures of the Rsub(1-x)Alsub(x)Co 5 alloys (R = Ce and Pr) in the composition range 0 = 5 and PrCo 5 phases. (author)

  1. Unexpected formation of hydrides in heavy rare earth containing magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yuanding Huang

    2016-09-01

    Full Text Available Mg–RE (Dy, Gd, Y alloys show promising for being developed as biodegradable medical applications. It is found that the hydride REH2 could be formed on the surface of samples during their preparations with water cleaning. The amount of formed hydrides in Mg–RE alloys is affected by the content of RE and heat treatments. It increases with the increment of RE content. On the surface of the alloy with T4 treatment the amount of formed hydride REH2 is higher. In contrast, the amount of REH2 is lower on the surfaces of as-cast and T6-treated alloys. Their formation mechanism is attributed to the surface reaction of Mg–RE alloys with water. The part of RE in solid solution in Mg matrix plays an important role in influencing the formation of hydrides.

  2. Comprehensive health protection measures and its effects at the Bayun Obo Rare-earth Iron mine in China

    International Nuclear Information System (INIS)

    Chen, Xing-an; Cheng, Yong-e

    2008-01-01

    The purpose of this paper is to present the comprehensive sanitary protection methods carried out by the authors at Bayun Obo Rare-earth Iron Mine. The methods are as follows. First, comprehensive measures to prevent dusts in the air. Second, enhancement of the individual protection measures; Third, promoting long-distance running and the establishment a workers. club; Fourth, the establishment of job rotation system; Fifth, increasing the transparency of the medical examination results, paying more attention to the health of the miners; Sixth, publicizing the value of stopping smoking. Results showed that the above-mentioned six aspects of comprehensive sanitary protection methods which we instituted brought about predominant effects. For example, the average dust concentrations in the air at 7 locations in the crushing workshop and 6 in the mining workshop decreased from 1143.67 mg.m -3 in January to June 1983 to 47.617 mg.m -3 in January to June 1991, and to 13.4 mg.m -3 in 2001. In 1983 the average thorium lung burden of 130 dust exposed miners selected by random stratification was 0.85 Bq, while the average thorium lung burden of 135 dust-exposed miners, similarly selected in 1991 was 0.25 Bq, a decrease by a factor of 3.4. It is concluded that the comprehensive health protection measures carried out by the authors for about 20 years in Bayun Obo Mine were proved very effective and should be continued and improved. It is also valuable to recommend our experience to other rare-earth mines and factories as well as thorium dusty units both in China and abroad. (author)

  3. Derivative thermo analysis of the Al-Si cast alloy with addition of rare earths metals

    Directory of Open Access Journals (Sweden)

    M. Krupiński

    2010-01-01

    Full Text Available In this paper the dependence between chemical composition, structure and cooling rate of Al–Si aluminium cast alloy was investigated. For studying of the structure changes the thermo-analysis was carried out, using the UMSA (Universal Metallurgical Simulator and Analyzer device. For structure investigation optical and electron scanning microscopy was used, phase and chemical composition of the Al cast alloy also using qualitative point-wise EDS microanalysis.

  4. Hydrogenation of the rare earth alloys for production negative electrodes of nickel-metal hydride batteries

    International Nuclear Information System (INIS)

    Casini, Julio Cesar Serafim

    2011-01-01

    In this work were studied of La 0.7-x Mg x Pr 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 (X = 0 and 0.7) alloys for negative electrodes of the nickel-metal hydride batteries. The hydrogenation of the alloys was performed varying pressing of H 2 (2 and 10 bar) and temperature (room and 500 ℃). The discharge capacity of the nic kel-metal hydride batteries were analyzed in ARBIN BT- 4 electrical test equipment. The as-cast alloys were analyzed by scanning electron microscopy (SEM), energy disperse spectroscopy (EDX) and X-Ray diffraction. The increasing Mg addition in the alloy increases maximum discharge capacity but decrease cycle life of the batteries. The maximum discharge capacity was obtained with the Mg 0.7 Pr 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 alloy (60 mAh) and the battery which presented the best performance was La 0.4 Mg 0.3 Pr 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 alloy (53 mAh and 150 cycles). The H 2 capability of absorption was diminished for increased Mg addition and no such effect occurs for Mg 0.7 Pr 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 alloy. (author)

  5. Passive behavior of magnesium alloys (Mg-Zr) containing rare-earth elements in alkaline media

    International Nuclear Information System (INIS)

    Pinto, R.; Ferreira, M.G.S.; Carmezim, M.J.; Montemor, M.F.

    2010-01-01

    The passive behavior of magnesium alloys ZK31, EZ33 and WE54 was studied in alkaline media (NaOH - pH 13) in the presence and absence of chloride ions. The electrochemical properties were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and capacitance measurements. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the study of the chemical composition and surface morphology of the surface films, respectively. The electrochemical impedance results revealed that the film formed on the surface of the three alloys is characterized by an increasing resistance, which stabilized with time. In the absence of chloride the film resistance was identical for all the three alloys. However, in the presence of chloride, the resistance of the film formed on the EZ33 alloy dropped nearly one order of magnitude comparatively to the other alloys. Generally, in the presence of chloride there was a decrease of the conductive character of the film. The films are homogeneous and, according to the XPS results, the outer layer seemed mainly composed of Mg(OH) 2 and the internal layer composed of MgO, independently of the presence of chloride. The AFM study revealed that the presence of chloride affected film morphology, namely nano-crystallites dimensions and aggregates size that increased.

  6. Corrosion resistance and microstructure characterization of rare-earth-transition metal-aluminum-magnesium alloys

    International Nuclear Information System (INIS)

    Banczek, E.P.; Zarpelon, L.M.C.; Faria, R.N.; Costa, I.

    2009-01-01

    This paper reports the results of investigation carried out to evaluate the corrosion resistance and microstructure of some cast alloys represented by the general formula: La 0.7-x Pr x Mg 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 (x = 0, 0.1, 0.3, 0.5, and 0.7). Scanning electron microscopy (SEM) and electrochemical methods, specifically, polarization curves and electrochemical impedance spectroscopy (EIS), have been employed in this study. The effects of Pr substitution on the composition of the various phases in the alloys and their corrosion resistance have been studied. The electrochemical results showed that the alloy without Pr and the one with total La substitution showed the highest corrosion resistance among the studied alloys. The corrosion resistance of the alloys decreased when Pr was present in the lowest concentrations (0.1 and 0.3), but for higher Pr concentrations (0.5 and 0.7), the corrosion resistance increased. Corrosion occurred preferentially in a Mg-rich phase.

  7. Sealing of Anodised Aluminium Alloys with Rare Earth Metal Salt Solutions

    OpenAIRE

    Mansfield, C.; Chen, F.; Breslin, Carmel B.; Dull, D.

    1998-01-01

    Boric‐sulfuric acid anodized (BSAA) aluminum alloys have been sealed in hot solutions of cerium or yttrium salts. For comparison, sealing has also been performed in the presently used dilute chromate solution, boiling water, and a cold nickel fluoride solution. The corrosion resistance of the sealed BSAA Al alloys Al 2024, Al 6061, and Al 7075 has been evaluated by recording impedance spectra during exposure in 0.5 N NaCl for 7 days. Shorter or longer exposure times have also been used depend...

  8. Recovery of cobalt-rare earth alloy particles by hydration-disintegration in a magnetic field

    International Nuclear Information System (INIS)

    McFarland, C.M.; Lerman, T.B.; Rockwood, A.C.

    1975-01-01

    A process for recovering magnetic alloy particles from a reaction product cake. The cake is placed in a reactor where it is contacted with a flowing water vapor-carrying gas which reacts with its calcium content to disintegrate the cake and produce a hydrated powder comprised substantially of calcium hydroxide and the alloy particles. A magnetic zone is generated into a cross-section of the reactor substantially encircling the inside wall thereof. The zone is generated by at least two poles of opposite polarity running the length of the zone. The hydrated powder is fluidized to dissociate and pass the calcium hydroxide out of the reactor. Finer-sized alloy particles carried by the fluidizing gas into the magnetic zone are subjected to the magnetic field where the poles are rotated or reversed at a rate which reverses the positions of the particles sufficiently to release adherent calcium hydroxide leaving the finer-sized alloy particles substantially within the magnetic zone. (auth)

  9. Magnetic properties analysis of intermetallic alloys Rni5 (R = Rare Earths)

    International Nuclear Information System (INIS)

    Barthem, V.M.T.S.

    1988-01-01

    SmNi 5 and TmNi 5 alloys were analysed by magnetization measures, susceptibility, resistivity and only for TmNi 5 by magnetostriction and thermal expansion. The results are distinguished by powerful magnetic anisotropy of these materials. (C.G.C.) [pt

  10. Study of hydrogenation for pulverization of rare earth alloys with Nb for metal hydride electrodes

    International Nuclear Information System (INIS)

    Ferreira, Eliner Affonso

    2013-01-01

    In this work were studied La ,7 Mg 0,3 Al 0,3 Mn 0,4 Co (0.5-x) NbxNi 3.8 (x= 0 - 0.5) and La 0,7 Mg 0,3 Al 0,3 Mn 0.4 Nb (05+x) Co 0,5 Ni (3.8-x) . (x=0.3; 0.5;1.3) alloys for negative electrodes of the Nickel-Metal Hydride batteries. The hydrogenation of the alloys was performed varying pressing of H 2 (2 and 9 bar). The discharge capacity of the nickel-metal hydride batteries were analyzed in the Arbin BT-4 electrical test equipment. The as-cast alloys were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-Ray diffraction. The increasing Niobium addition in the alloys decreased cycle life and the maximum discharge capacity of the batteries. The maximum discharge capacity was obtained with the La .7 Mg 0.3 Al 0.3 Mn 0,4 Co 0.5 Ni 3.8 (45.36 mAh) and the battery which presented the best performance was La .7 Mg 0.3 Al 0.3 Mn 0.4 Co 0.5 Nb 0.1 Ni 3.8 (44.94 mAh). (author)

  11. The role of intermetallic phases in the corrosion of magnesium-rare earth alloys

    Energy Technology Data Exchange (ETDEWEB)

    Silva Campos, Maria del Rosario

    2016-07-25

    A new concept to develop a RE based Mg alloy with improved corrosion resistance was followed in the current work. Based on subsequent characterisation steps to eliminate less suitable RE elements the best microstructure for improved corrosion resistance was identified. At first, the corrosion properties of selected RE elements were determined. Based on these results RE elements that have a potential to enhance the corrosion resistance of Mg-RE alloys were selected. Two aspects of RE elements were important for the selection: the electrochemical properties and the solid solubility in Mg. If the solubility limit of RE elements in the Mg matrix is exceeded, they form intermetallic phases with Mg. By performing galvanic coupling measurements the compatibility between Mg matrix and intermetallic phases were estimated. At that point three binary Mg-RE alloys systems remained (Mg-Ce, Mg-La, and Mg-Gd). To evaluate the influence of composition (amount of intermetallic phases) on the corrosion behaviour, four concentrations were cast with 1, 5, 10 and 15 wt. % of RE. Ce and La have a lower solid solubility in Mg matrix generating higher volume fraction of the secondary phases, thus higher dissolution rates in the binary Mg-RE alloys. While Gd with higher solid solubility shows a different behaviour. Additions of up to 10 wt. % Gd resulted in similar behaviour compared to 1 wt. % Gd addition. The most promising results were obtained for the Mg-Gd system with 10 wt. % Gd. Thus, the microstructure of this alloy was further modified by heat treatments to understand the influence of microstructural changes on corrosion behaviour. A ternary element was used to attempt further optimisation of the corrosion performance. Additions of Al, Zn, Ga and Y did not show any improvement in the corrosion resistance of Mg10Gd. This is due to increasing volume fractions of critical more noble phases and the microstructure dominated by eutectic phase formation. Thus galvanic effects became much

  12. The role of intermetallic phases in the corrosion of magnesium-rare earth alloys

    International Nuclear Information System (INIS)

    Silva Campos, Maria del Rosario

    2016-01-01

    A new concept to develop a RE based Mg alloy with improved corrosion resistance was followed in the current work. Based on subsequent characterisation steps to eliminate less suitable RE elements the best microstructure for improved corrosion resistance was identified. At first, the corrosion properties of selected RE elements were determined. Based on these results RE elements that have a potential to enhance the corrosion resistance of Mg-RE alloys were selected. Two aspects of RE elements were important for the selection: the electrochemical properties and the solid solubility in Mg. If the solubility limit of RE elements in the Mg matrix is exceeded, they form intermetallic phases with Mg. By performing galvanic coupling measurements the compatibility between Mg matrix and intermetallic phases were estimated. At that point three binary Mg-RE alloys systems remained (Mg-Ce, Mg-La, and Mg-Gd). To evaluate the influence of composition (amount of intermetallic phases) on the corrosion behaviour, four concentrations were cast with 1, 5, 10 and 15 wt. % of RE. Ce and La have a lower solid solubility in Mg matrix generating higher volume fraction of the secondary phases, thus higher dissolution rates in the binary Mg-RE alloys. While Gd with higher solid solubility shows a different behaviour. Additions of up to 10 wt. % Gd resulted in similar behaviour compared to 1 wt. % Gd addition. The most promising results were obtained for the Mg-Gd system with 10 wt. % Gd. Thus, the microstructure of this alloy was further modified by heat treatments to understand the influence of microstructural changes on corrosion behaviour. A ternary element was used to attempt further optimisation of the corrosion performance. Additions of Al, Zn, Ga and Y did not show any improvement in the corrosion resistance of Mg10Gd. This is due to increasing volume fractions of critical more noble phases and the microstructure dominated by eutectic phase formation. Thus galvanic effects became much

  13. Site preference of rare earth doping in palladium-iron-arsenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Stuerzer, Christine; Schulz, Anne; Johrendt, Dirk [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

    2014-12-15

    The solid solutions (Ca{sub 1-y}RE{sub y}Fe{sub 1-x}Pd{sub x}As){sub 10}Pd{sub z}As{sub 8} with RE = La, Ce, and Pr were synthesized by solid state methods and characterized by X-ray powder diffraction with subsequent Rietveld refinements [(CaFeAs){sub 10}Pt{sub 3}As{sub 8}-type structure (''1038 type''), P anti 1, Z = 1]. Substitution levels (Ca/RE, Fe/Pd, and Pd/□) obtained from Rietveld refinements coincide well with the nominal values according to EDS and the linear courses of the lattice parameters as expected from the ionic radii. The RE atoms favor the one out of five calcium sites, which is eightfold coordinated by arsenic. This leads to significant stabilization of the structure, and especially prevents palladium over-doping in the iron-arsenide layers as observed in the pristine compound (CaFe{sub 1-x}Pd{sub x}As){sub 10}Pd{sub z}As{sub 8}. While the stabilization energy is estimated to about 40 kJ.mol{sup -1} by electronic structure calculations, the reason for the diminished Fe/Pd substitution through RE doping is still not yet understood. We suggest that the electrons transferred from RE{sup 3+} to the (Fe{sub 1-x}Pd{sub x})As layer makes higher palladium concentrations unfavorable. Anyway the reduced palladium doping enables superconductivity with critical temperatures up to 20 K (onset) in the RE doped Pd1038 samples, which could not be obtained earlier due to palladium over-doping in the active iron-arsenide layers. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Microstructure, corrosion resistance and cytocompatibility of Mg-5Y-4Rare Earth-0.5Zr (WE54) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Smola, Bohumil, E-mail: bohumil.smola@mff.cuni.cz [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Joska, Ludek [Institute of Chemical Technology Prague, Faculty of Chemical Technology, Technicka 5, 166 28 Praha 6 (Czech Republic); Brezina, Vitezslav [University of South Bohemia, Institute of Physical Biology, Zamek 136, 373 33 Nove Hrady (Czech Republic); Stulikova, Ivana [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Hnilica, Frantisek [Czech Technical University in Prague, Faculty of Mechanical Engineering, Karlovo namesti 13, 121 35 Praha 2 (Czech Republic)

    2012-05-01

    Conventionally cast Mg-5Y-4Rare Earth-0.5Zr alloy (WE54) was solution treated (525 Degree-Sign C/8 h - T4) and one part subsequently aged (200 Degree-Sign C/16 h - T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250 Degree-Sign C or 400 Degree-Sign C. Dense triangular arrangement of prismatic plates of transient D0{sub 19} and C-base centered orthorhombic phases precipitated in the {alpha}-Mg matrix during the T6 treatment. Both alloys prepared by powder metallurgy exhibit similar microstructure consisting of {approx} 4-6 {mu}m {alpha}-Mg matrix fibers surrounded by particles of the equilibrium Mg{sub 5}(Y, Nd) phase and of oxides. Open circuit potential and polarization resistance in the isotonic saline (9 g/l NaCl/H{sub 2}O) were monitored for 24 h. The corrosion rate of the T4 and T6 treated alloys was about 80 times lower than that of commercial Mg. Both alloys prepared by powder metallurgy exhibited approximately 8 times higher corrosion resistance than commercial Mg. The human MG-63 osteoblast-like cells spreading and division in the extracts (0.28 g in 28 ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24 h. The MG-63 cells proliferate without cytotoxicity in all extracts. - Highlights: Black-Right-Pointing-Pointer T6 treated WE54 alloy exhibit dense triangular arrangement of {beta} Double-Prime and {beta} Prime phase prismatic plates. Black-Right-Pointing-Pointer Microstructure of PM prepared WE54 alloy consists of {alpha}-Mg phase cells surrounded by {beta} phase particles. Black-Right-Pointing-Pointer PM produced WE54 corroded 10 times faster in physiological solution thanT4 and T6 treated WE54. Black-Right-Pointing-Pointer MG63 cell spreading in EMEM extracts of PM prepared WE54 is comparable to that in control EMEM. Black-Right-Pointing-Pointer Cell mitosis is enhanced in PM WE54 extracts compared to the control and extracts of T4 and T6 WE54.

  15. Studies of the rare earth-iron interactions in the orthoferrites GdFeO3 and HoFeO3

    International Nuclear Information System (INIS)

    Sakata, T.; Enomura, A.

    1979-01-01

    The magnetic behaviour of GdFeO 3 and HoFeO 3 is investigated by means of a Faraday type magnetic balance in a temperature range where rare earth ions are in the paramagnetic state. The results are analyzed in terms of an effective field at a rare earth ion site. Thereby the isotropic exchange field as well as the magnetic dipole field are taken into account. By this means the exchange integral, J/k(K), between an iron ion and a rare earth ion may be estimated to be 0.23 for GdFeO 3 and 0.25 for HoFeO 3 , respectively. (author)

  16. Investigation on fuel-cladding chemical interaction in metal fuel for FBR. Reaction of rare earth elements with Fe-Cr alloy

    International Nuclear Information System (INIS)

    Inagaki, Kenta; Ogata, Takanari

    2010-01-01

    Rare-earth fission product (FP) elements generated in the metal fuel interact with cladding alloy and result in the wastage of the cladding (Fuel-Cladding Chemical Interaction (FCCI)). To evaluate FCCI quantitatively, several influential factors must be considered. They are temperature, temperature gradient, time, composition of the cladding and the behavior of rare-earth FP. In this research, the temperature and time dependencies are investigated with tests in the simplified system. Fe-12wt%Cr was used as stimulant material of cladding and rare-earth alloy 13La -24Ce -12Pr -39Nd -12Sm (RE) as a rare-earth FP. A diffusion couple Fe-Cr/RE was made and annealed at 923K, 853K, 773K or 693K. The structures of reaction layers were analyzed with Electron Probe Micro Analyzer (EPMA) and the details of the structures were clarified. The width of the reaction layer in the Fe-Cr alloy grew in proportion to the square root of time. The reaction rate constants K=(square of the width of reaction layer / time) were evaluated. It was confirmed that the relation between K and the inverse of the temperature showed linearity above 773 K. (author)

  17. Rare-Earth Surface Alloying: A New Phase for GdAu2

    International Nuclear Information System (INIS)

    Corso, M.; Schiller, F.; Fernandez, L.; Verstraete, M. J.; Ormaza, M.; Greber, T.; Torrent, M.; Rubio, A.; Ortega, J. E.

    2010-01-01

    Surface alloying is a powerful way of varying physical and chemical properties of metals, for a number of applications from catalysis to nuclear and green technologies. Surfaces offer many degrees of freedom, giving rise to new phases that do not have a bulk counterpart. However, the atomic characterization of distinct surface compounds is a major task, which demands powerful experimental and theoretical tools. Here we illustrate the process for the case of a GdAu 2 surface phase of extraordinary crystallinity. The combined use of surface-sensitive techniques and state-of-the-art ab initio calculations disentangles its atomic and electronic properties. In particular, the stacking of the surface layers allows for gadolinium's natural ferromagnetic state, at variance with the bulk phase, where frustration leads to antiferromagnetic interlayer coupling.

  18. Preparation of Trivalent Chromium and Rare Earth Composite Conversion Coating on Aluminum Alloy Surface

    Science.gov (United States)

    Huang, Jianzhen

    2018-01-01

    In this paper, the surface conversion film on 6063 aluminum alloy was prepared by chemical plating process with chromium sulfate, lanthanum sulfate and sodium phosphate as film forming agent. The corrosion resistance and surface morphology of the conversion film were analyzed by pitting corrosion test of copper sulfate and SEM. The results show that when Cr2(SO4)3 is 10 g/L, La2(SO4)3 is 2 g/L, Na3PO4 is 8 g/L, pH value is 3, temperature is 40 °C, reaction time is 10 min, the corrosion resistance of the surface conversion film is the best. The conversion coating is light green, composed of Cr, La, P, Al, O and other elements.

  19. Microstructure and mechanical behaviour of an elevated temperature Mg-rare earth based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bettles, C.J. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Clayton 3800, Vic. (Australia); CAST CRC, CSIRO Materials Science and Engineering, Private Bag 33, Clayton South MDC, Clayton 3169, Vic. (Australia)], E-mail: colleen.bettles@eng.monash.edu.au; Gibson, M.A. [CAST CRC, CSIRO Materials Science and Engineering, Private Bag 33, Clayton South MDC, Clayton 3169, Vic. (Australia); Zhu, S.M. [CAST CRC, Department of Materials Engineering, Monash University, Clayton 3800, Vic. (Australia)

    2009-04-15

    AM-SC1 is a heat treatable magnesium alloy that has been specifically developed to achieve the elevated temperature strength and creep properties necessary for engine block applications. This paper describes the interrelationship between the microstructure and the mechanical properties of AM-SC1. The compressive and tensile strengths are relatively insensitive to temperature up to and including 450 K and the tensile yield behaviour deviates from a standard Hall-Petch relationship at grain sizes below 200 {mu}m. The microstructural features contributing to the creep resistance are both inter- and intra-granular in nature and are on length scales from nanometers to micrometers. The creep behaviour at 423 K and 450 K is diffusion controlled, with any contribution from the grain boundaries being negligible.

  20. Effect of rare earth element on microstructure formation and mechanical properties of thin wall ductile iron castings

    International Nuclear Information System (INIS)

    Choi, J.O.; Kim, J.Y.; Choi, C.O.; Kim, J.K.; Rohatgi, P.K.

    2004-01-01

    Ductile iron castings with 2, 3, 4, 6, 8, and 25 mm thickness and various amount of rare earth elements (RE) (from 0 to 0.04%), were cast in sand molds to identify the effects of sample thickness and the content of RE% on microstructural formation and selected mechanical properties. The effects of RE content and sample thickness on microstructural formation, including on graphite nodule count, graphite nodule shape, spherodization, and ferrite amount, were observed. The yield strength of the samples with RE within the range investigated were lower than those of the specimens without RE. The elongation was improved with the addition of RE up to 0.03% in ductile iron castings. The additions of 0.02% RE caused a smaller graphite nodule size and a higher number of graphite nodules than those in the specimen without RE at all levels of RE addition; the nodule count decreased with increase in section size. The chill zones were observed in the 2 mm thick samples, but were absent in the samples from castings which were thicker than 2 mm, irrespective of the addition of RE. The nodularity of graphite nodules improved due to the addition of 0.02-0.04% RE. The specimens with RE content up to 0.03% had a lower tensile strength and hardness, higher elongation than that of the specimens without RE. The ferrite content in all castings increased with additions of 0.02% RE. The tensile strengths of the 2 and 3 mm thick samples were also estimated using the relationship between strength and hardness, obtained from the data on the tensile strength and hardness of the 25 mm thick samples

  1. Rare earth elements and uranium in fountain waters from different towns of the Iron Quadrangle, MG, Brazil

    International Nuclear Information System (INIS)

    Ferreira, Claudia A.; Palmieri, Helena E.L.; Menezes, Maria Angela de B.C.

    2015-01-01

    Rare earth elements (REE) and uranium were evaluated in 34 fountain waters collected in different towns of the Iron Quadrangle (IQ), Minas Gerais, Brazil. The IQ is one of the largest and most well-known mineral deposits in the world. Not only extensive iron deposits but also hydrothermal gold deposits are found in this region. Because of the toxicological properties of REE, monitoring of groundwater which is used for drinking water may be useful if relatively high concentrations of REE are expected. The total REE (ΣREE) concentrations in fountain water range from 3 to 33395 ng L -1 . It was observed that fountains with a pH value below 5 presented higher concentration values of the determined elements proposed in this work. This is due to the fact that waters exhibiting low pH values enhance the dissolution of these elements. Moreover, for uranium the values ranged from less than < 2 to 540 ng L -1 . The highest concentrations in waters were observed only in four cities. Statistical methods such as Pearson correlation, PCA and HCA analysis were applied to the data set to shed some light on the behavior of the elements in water in this study. Three major groups with similar characteristics were identified and six diagrams of REE signatures in fountain waters were plotted according to their groupings of subdivisions. Using the REE-Post-Archean Australian Shale (PAAS) normalized patterns it was possible to verify presence of distinct REE signatures and recognize that the two samples belong to the same aquifer type. (author)

  2. Origin of the reversed yield asymmetry in Mg-rare earth alloys at high temperature

    International Nuclear Information System (INIS)

    Hidalgo-Manrique, P.; Herrera-Solaz, V.; Segurado, J.; Llorca, J.; Gálvez, F.; Ruano, O.A.; Yi, S.B.; Pérez-Prado, M.T.

    2015-01-01

    The mechanical behaviour in tension and compression of an extruded Mg–1 wt.% Mn–1 wt.% Nd (MN11) alloy was studied along the extrusion direction in the temperature range −175 °C to 300 °C at both quasi-static and dynamic strain rates. Microstructural analysis revealed that the as-extruded bar presents a recrystallized microstructure and a weak texture that remain stable in the whole temperature range. A remarkable reversed yield stress asymmetry was observed above 150 °C, with the compressive yield stress being significantly higher than the tensile yield stress. The origin of this anomalous reversed yield stress asymmetry, which to date remains unknown, was investigated through the analysis of the macro and microtexture development during deformation, as well as by means of crystal plasticity finite element simulations of a representative volume element of the polycrystal. The critical resolved shear stresses of slip and twining for simulated single crystals were obtained as a function of the temperature by means of an inverse optimisation strategy. Experimental and simulation results suggest that the reversed yield asymmetry may be primarily attributed to the non-Schmid behaviour of pyramidal 〈c + a〉 slip, which is the dominant deformation mechanism at high temperatures. It is proposed, furthermore, that the asymmetry is enhanced at quasi-static strain rates by the stronger interaction of 〈c + a〉 dislocations with the diffusing solute atoms and particles in compression than in tension

  3. Enhanced hot ductility of a Cr–Mo low alloy steel by rare earth cerium

    International Nuclear Information System (INIS)

    Jiang, X.; Song, S.-H.

    2014-01-01

    The hot ductility of a 1Cr–0.5Mo low alloy steel is investigated over a temperature range of 700–1050 °C using a Gleeble thermomechanical simulator in conjunction with various characterization techniques. The steel samples undoped and doped with cerium are heated at 1300 °C for 3 min and then cooled with a rate of 5 K s −1 down to different test temperatures, followed by tensile deformation until fracture. The results show that the hot ductility of the steel, evaluated by the reduction in area, can be substantially enhanced by a minor addition of cerium, especially in the range 800–1000 °C. In the austenite–ferrite dual-phase region, cerium may delay the formation of proeutectoid ferrite layers along austenite grain boundaries, thereby increasing the hot ductility of the steel. In the single austenite region, grain boundary segregation of cerium may increase the grain boundary cohesion, toughening the steel and thus raising the resistance to grain boundary sliding as well as promoting dynamic recrystallization. Consequently, the hot ductility of the steel is enhanced

  4. A metallurgical approach toward alloying in rare earth permanen magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    Branagan, Daniel J. [Iowa State Univ., Ames, IA (United States)

    1995-02-23

    The approach was developed to allow microstructural enhancement and control during solidification and processing. Compound additions of Group IVA, VA, or VIA transition metals (TM) and carbon were added to Nd2Fe14B (2-14-1). Transition metal carbides formed in IVA (TiC, ZrC, HfC) and Group VA (VC, NbC, TaC) systems, but not in the VIA system. The alloying ability of each TM carbide was graded using phase stability, liquid and equilibrium solid solubility, and high temperature carbide stability. Ti with C additions was chosen as the best system. The practically zero equilibrium solid solubility means that the Ti and C additions will ultimately form TiC after heat treatment which allows the development of a composite microstructure consisting of the 2-14-1 phase and TiC. Thus, the excellent intrinsic magnetic properties of the 2-14-1 phase remain unaltered and the extrinsic properties relating to the microstructure are enhanced due to the TiC stabilized microstructure which is much more resistant to grain growth. When Ti + C are dissolved in the liquid melt or solid phases, such as the glass or 2-14-1 phase, the intrinsic properties are changed; favorable changes include increased glass forming ability, reduced optimum cooling rate, increased optimum energy product, and enhanced nucleation kinetics of crystallization.

  5. Ternary and quaternary solid solutions in rare earth alloy phases with the CaCu5-type structure

    International Nuclear Information System (INIS)

    Malani, G.K.; Raman, A.; Mohanty, R.C.

    1992-01-01

    Crystal structural data were analyzed in seleced CaCu 5 -type ternary and quaternary solid solutions to assess the crystal chemical characteristics and stability features of the CaCu 5 -type structure in rare earth containing alloy phases. LaNi 5 was found to dissolve 100 mol% LaCu 5 , 100 mol% ErNi 5 , about 50 mol% LaIr 5 , 40 mol% 'LaMn 5 ', 20 mol% 'LaFe 5 ', and 25 mol% ErRh 5 . In contrast, LaCo 5 did not dissolve any Mn or any of the other elements other than Al - it dissolved about 20 mol% 'LaAl 5 '. LaCu 5 behaves similar to LaNi 5 in solid solutions. From the lack of solubility of any other element in LaFe 5 , LaCo 5 , LaRh 5 , and LaIr 5 and their great instability, these are inferred to be borderline cases in the realm of the CaCu 5 -type structure. In the CaCu 5 and related crystal structures, Ir is compatible with Ni, but not with Co or Rh, and Rh is not compatible with either Ni or Ir. (orig.) [de

  6. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    Rare earth germanates attract close attention both as an independent class of compounds and analogues of a widely spread class of natural and synthetic minerals. The methods of rare earth germanate synthesis (solid-phase, hydrothermal) are considered. Systems on the basis of germanium and rare earth oxides, phase diagrams, phase transformations are studied. Using different chemical analysese the processes of rare earth germanate formation are investigated. IR spectra of alkali and rare earth metal germanates are presented, their comparative analysis being carried out. Crystal structures of the compounds, lattice parameters are studied. Fields of possible application of rare earth germanates are shown

  7. Rare earth elements: end use and recyclability

    Science.gov (United States)

    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.

  8. Solubility of rare earth-iron borates in the Bi2O3-B2O3 melt and their crystallization

    International Nuclear Information System (INIS)

    Al'shinskaya, L.I.; Leonyuk, N.I.; Nadezhnaya, T.B.; Timchenko, T.I.

    1979-01-01

    The temperature dependence of solubility of RFe 3 (BO 3 ) 4 (R=Y, Gd, Nd, Er) double borates in the Bi 2 O 3 -B 2 O 3 solution-melt is studied. The solubility curves in the range from 25 to 52 mol% are plotted. The character of curves is almost similar. At equal temperatures YFe 3 (BO 3 ) 4 and ErFe 3 (BO 3 ) 4 have the highest solubility and GaFe 3 (BO 3 ) 4 - the lowest one. It is shown that in the Bi 2 O 3 -B 2 O 3 base solution-melt the wide temperature range of monophase crystallization of rare earth - iron borates exists and the stratification is not observed. Thus, for the first time obtained are the crystals of rare earth-iron borates suitable for the investigation of their physical properties

  9. Hydrometallurgical method for recycling rare earth metals, cobalt, nickel, iron, and manganese from negative electrodes of spent Ni-MH mobile phone batteries

    International Nuclear Information System (INIS)

    Santos, Vinicius Emmanuel de Oliveira dos; Lelis, Maria de Fatima Fontes; Freitas, Marcos Benedito Jose Geraldo de

    2014-01-01

    A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni-MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO 4 ) 2 .H 2 O) and lanthanum sulfate (La 2 (SO 4 ) 3 .H 2 O) as the major recovered components. Iron was recovered as Fe(OH) 3 and FeO. Manganese was obtained as Mn 3 O 4 .The recovered Ni(OH) 2 and Co(OH) 2 were subsequently used to synthesize LiCoO 2 , LiNiO 2 and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques. (author)

  10. Effect of Ce-rich rare earth on microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy

    Directory of Open Access Journals (Sweden)

    You Zhiyong

    2012-05-01

    Full Text Available To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy, different amount of Ce-rich rare earth (RE was added to the alloy, and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy (SEM, energy dispersive spectroscope (EDS and X-ray diffraction (XRD. The results show that an appropriate amount of Ce-rich rare earth addition can make the Al4Ce phase particles and CeSb phase disperse more evenly in the alloy. These phases refine the alloy抯 matrix and make the secondary phases [t-Mg32(Al,Zn49 phase and f-Al2Mg5Zn2 phase] finer and more dispersive, therefore significantly improve the mechanical properties of the Mg-10Zn-5Al-0.1Sb alloy. When the RE addition is 1.0 wt.%, the tensile strengths of the alloy both at room temperature and 150 篊 reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy. The hardness increases with the increase of RE addition.

  11. Rare earth sulfates

    International Nuclear Information System (INIS)

    Komissarova, L.N.; Shatskij, V.M.; Pokrovskij, A.N.; Chizhov, S.M.; Bal'kina, T.I.; Suponitskij, Yu.L.

    1986-01-01

    Results of experimental works on the study of synthesis conditions, structure and physico-chemical properties of rare earth, scandium and yttrium sulfates, have been generalized. Phase diagrams of solubility and fusibility, thermodynamic and crystallochemical characteristics, thermal stability of hydrates and anhydrous sulfates of rare earths, including normal, double (with cations of alkali and alkaline-earth metals), ternary and anion-mixed sulfates of rare earths, as well as their adducts, are considered. The state of ions of rare earths, scandium and yttrium in aqueous sulfuric acid solutions is discussed. Data on the use of rare earth sulfates are given

  12. Rare-earth elements

    Science.gov (United States)

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

    2017-12-19

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

  13. Surface modification method of rare earth-nickel hydrogen storage alloy for a battery; Denchiyo kidorui-nikkeru kei suiso kyuzo gokin no hyomen kaishitsu shoriho

    Energy Technology Data Exchange (ETDEWEB)

    Higashiyama, N.; Kimoto, M.; Matsuura, Y.; Kuroda, Y.; Nogami, M.; Nishio, K.; Saito, T.

    1996-07-16

    The characteristics of an alkaline battery with hydrogen storage alloy depend significantly on the activity of the used rare earth-nickel hydrogen storage alloy and require an activation process in its manufacturing. However, the previous manufacturing method was found to have a defect that surface modification cannot be uniformly conducted due to a rapid increase of pH of the processing solution during the processing. This invention aims to present a surface modification method to enable to produce uniform surface of the alloy particles with a high activity. In this invention, the rare earth-nickel hydrogen storage alloy is immersed in a buffer solution of pH 1 to 3.6 for a fixed period followed by washing with water or an alkaline solution. The rapid change of pH can be avoided by the use of the buffer solution and the surface of the alloy particles is modified uniformly. The use of the obtained alloy suppresses the increase of the internal pressure in the battery during charging and affords an alkaline battery with a long cycle life and a high performance. 1 fig., 3 tabs.

  14. Corrosion mitigation of rare-earth metals containing magnesium EV31A-T6 alloy via chrome-free conversion coating treatment

    International Nuclear Information System (INIS)

    Hamdy, Abdel Salam; Butt, Darryl P.

    2013-01-01

    Highlights: • Protective stannate coatings have been proposed for rare-earth-EV31A-T6 magnesium alloy. • A simple coating method based on direct treatment of EV31A-T6 in a diluted stannate was found promising. • Surface modification prior to stannate coating offer no substantial advantage over directly coating. • Stannate conversion coatings decrease corrosion rates by a factor of 1/7. • The coating does not display any self-healing characteristics as shown in AZ91D. -- Abstract: Magnesium alloys posses unique mechanical and physical characteristics making them attractive light-weight materials for several strategic industries such as electronics, computer, automotive and aerospace. Due to their high chemical reactivity and poor corrosion resistance, the protection of magnesium alloys from corrosion is one of the hottest topics in materials science and engineering. Addition of rare-earth metals (RE) as alloying elements to magnesium alloys is one of the common approaches to improve their mechanical properties and, sometimes, the corrosion resistance. However, the potential difference between the RE metals phase formed in the Mg matrix enhances the galvanic corrosion at the interfaces where RE metals inert phase acts as cathode and the active Mg matrix acts as anode. This paper introduces a simple one-step clean conversion coating treatment for improving the protection of RE containing magnesium EV31A-T6 alloy in Cl − media

  15. NMR study of electron spin density distribution in rare-earth intermetallic compounds with iron and cobalt

    International Nuclear Information System (INIS)

    Vasil'kovskij, V.A.; Gorlenko, A.A.; Kupriyanov, A.K.; Ostrovskij, V.F.

    1988-01-01

    It is shown that in intermettalic compounds local fields in rare earth (RE) element nuclei directed by 3d-sublattice atoms depend on 3d-atom type but they practically do not depend on the value of its magnetic moment and the compound stoichiometry. The results are explained in the assumption concerning the presence of a system of collectivized electrons, their spin polarization determining the field in RE nuclei and contributing to 3d-atom magnetic moment

  16. Rare earth octacyanomolybdates(4)

    International Nuclear Information System (INIS)

    Zubritskaya, D.I.; Sergeeva, A.N.; Pisak, Yu.V.

    1980-01-01

    Optimal conditions for synthesis of rare-earth octacyanomolybdates(4) of the Ln 4 [Mo(CN) 8 ] 3 xnH 2 O composition (where Ln is a rare-earth element, other than Pr, Pm, Lu, Tb) have been worked out. The synthesis has been accomplished by neutralization with octacianomolybdic acid with rare-earth carbonates. The composition and structure of the compounds synthesized have been studied by infrared-spectroscopy. It has been established that rare-earth octacyanomolybdates(4) form three isostructural groups

  17. Column extraction chromatography with HEH (EHP) for separating rare earth elements from coexistent elements and its application

    International Nuclear Information System (INIS)

    Peng Chunlin; Sun Baocheng; Zhao Junwu; Liu Xuan

    1985-01-01

    For separating rare earths from large amount of coexistent elements a new method of column extraction chromatography with HEH (EHP) as a stationary phase and sulphosalicylic acid, gluconic acid, ascorbic acid respectively as a mobile phase has been developed. It has been applied to the determination of trace rare earth elements in nickel-base alloys and iron-nickel-base alloys with satisfactory results

  18. High coercivity rare earth-transition metal magnets

    International Nuclear Information System (INIS)

    Croat, J.J.

    1982-01-01

    Ferromagnetic compositions having intrinsic magnetic coercivities at room temperature of at least 1,000 Oersteds are formed by the controlled quenching of molten rare earth -transition metal alloys. Hard magnets may be inexpensively formed from the lower atomic weight lanthanide elements and iron. The preferable compositions lie within: at least one of Fe, Ni, Co (20 to 70 atomic percent); and at least one of Ce, Pr, Na, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y (80 to 30 atomic percent). (author)

  19. High coercivity rare earth-transition metal magnets

    International Nuclear Information System (INIS)

    Croat, J.J.

    1982-01-01

    Ferromagnetic compositions having intrinsic magnetic coercivities at room temperature of at least 1,000 Oersteds are formed by the controlled quenching of molten rare earth-transition metal alloys. Hard magnets may be inexpensively formed from the lower atomic weight lanthanide elements and iron. The preferable compositions lie within: at least one of Fe, Ni, Co; 20 - 70 atomic percent: at least one of Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y; 80 - 30 atomic percent. (author)

  20. Effect of rare earth elements on deformation behavior of an extruded Mg–10Gd–3Y–0.5Zr alloy during compression

    International Nuclear Information System (INIS)

    Mirza, F.A.; Chen, D.L.; Li, D.J.; Zeng, X.Q.

    2013-01-01

    Highlights: ► The alloy studied has threefold higher compressive yield strength than AM30 alloy. ► Formation of twins is less extensive than that in the RE-free extruded Mg alloys. ► Deformation of the RE-containing Mg alloy is characterized by three distinct stages. ► Rare earth elements effectively increase the strain hardening rate in stage A. ► Fairly flat and linear strain hardening occurs in stage B over an extended range. - Abstract: The aim of this study was to identify the influence of rare-earth (RE) elements on the strain hardening behavior in an extruded Mg–10Gd–3Y–0.5Zr magnesium alloy via compression in the extrusion direction at room temperature. The plastic deformation behavior of this RE-containing alloy was characterized by a rapidly decreasing strain hardening rate up to a strain level of about 4% (stage A), followed by a fairly flat linear strain hardening rate over an extended strain range from ∼4% to ∼18% (stage B). Stage C was represented by a decreasing strain hardening rate just before failure. The extent of twinning in this alloy was observed to be considerably less extensive than that in the RE-free extruded Mg alloys. The weaker crystallographic texture, refined grain size, and second-phase particles arising from the addition of RE elements were responsible for the much higher strain hardening rate in stage A due to the increased difficulty on the formation of twins and the slip of dislocations at lower strains, and for the occurrence of quite flat linear strain hardening in stage B at higher strains which was likely related to the dislocation debris and twin debris (or residual twins) stemming from dislocation–twin interactions as well as the interactions between dislocations/twins and second-phase particles and grain boundaries

  1. Crystalline and amorphous rare-earth metallic compounds

    International Nuclear Information System (INIS)

    Burzo, E.

    1975-01-01

    During the last years the study of magnetic behaviour of rare-earth (or yttrium) compounds with cobalt and iron has growth of interest. This interest of justified by a large area of experimental and theoretical problems coming into being in the study of some rare-earth materials as well as in their technical applications. In the last three years a great number of new rare earth materials were studied and also new models explaining the magnetic behaviour of these systems have been used. In this paper we refer especially to some typical systems in order to analyse the magnetic behaviour of iron and cobalt and also the part played by the magnetic interactions in the values of the cobalt or iron moments. The model used will be generally the molecular field model. In the second chapter we present comparatively the structure of crystalline and amorphous compounds for further correlation with the magnetic properties. In chapter III we analyse the magnetic interactions in some crystalline and amorphous rare-earth alloys. Finally, we exemplify the ways in which we ensure better requried characteristics by the technical utilizations of these materials. These have in view the modifications of the magnetic interactions and are closely related with the analysis made in chapter III

  2. Separation and Recovery of Iron and Rare Earth from Bayan Obo Tailings by Magnetizing Roasting and (NH4)2SO4 Activation Roasting

    OpenAIRE

    Yan Zhou; He Yang; Xiang-xin Xue; Shuai Yuan

    2017-01-01

    A novel approach for recovery of iron and rare earth elements (REEs) from Bayan Obo tailings of Baotou, China, was developed by combining magnetizing roasting, magnetic separation, (NH4)2SO4 activation roasting, and water leaching. Thermodynamic analysis of carbothermal reduction was conducted to determine the temperature of magnetizing roasting, and it agreed well with the experimental results. The maximum recovery of Fe reached 77.8% at 600 °C, and the grade of total Fe in the magnetic conc...

  3. The distribution of rare earth and other elements and the mineralogy of the iron oxyhydroxide phase in marine ferromanganese concretions from within Slupsk Furrow in the southern Baltic

    International Nuclear Information System (INIS)

    Ali, A.; Ikuta, K.; Latka, K.; Goerlich, E.A.; Kunzendorf, H.; Glasby, G.P.; Szefer, P.

    1998-01-01

    Rare earth element concentrations in ferromanganese concretions sampled from Slupsk Furrow in the Polish Exclusive Economic Zone are similar to those of concretions from the Gulf of Bothnia. The lack of positive Ce anomalies in the concretions from Slupsk Furrow indicates that they are formed under less oxidizing conditions than spheroidal concretions from the Gulf of Bothnia. Moessbauer studies indicate that poorly crystalline lepidocrosite is the principal iron oxyhydroxide mineral present in these concretions. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Dose-effect relationship between the thorium lung burden and the hepatic function of the miners at the Bayan Obo Rare-earth Iron Mine

    International Nuclear Information System (INIS)

    Cheng, Yong-e; Chen, Xing-an

    2008-01-01

    The purpose of this paper is to present the dose effect relationship between the thorium lung burden and the hepatic function of the miners at the Bayun Obo Rare-earth Iron Mine. The methods we used is to carry out the measurement of each miner.s exhaled thoron activity and the thorium lung burden along with the four hepatic functions (thymol turbidity test, glutamic pyruvic transaminase, thymol flocculation test and alkaline phosphatase)of the dust exposed miners in Bayun Obo Rare-earth Iron Mine. We have carried out three investigations in 1983, 1984-1987 and 1994 respectively. Results showed that during the period 1983-1994, 1158 measurements of thorium lung burden estimates and 1158 measurement of every four hepatic functions(altogether 4632 measurements) were performed on 638 dust-exposed miners. No adverse effects were observed. In the same time, none of the above-mentioned 638 exposed miners had a thorium lung burden higher than 11.11 Bq. It is concluded that if any miners. thorium lung burden not higher than 11.11 Bq, his four hepatic functions should not be affected. This first possible threshold for thorium lung burden affecting the hepatic functions was put forward by the authors and confirmed by the Information Center of Chinese Academy of Medical Science in 2003 after searching 23.6 million references. (author)

  5. Magnetic nanosized rare earth iron garnets R_3Fe_5O_1_2: Sol–gel fabrication, characterization and reinspection

    International Nuclear Information System (INIS)

    Opuchovic, Olga; Kareiva, Aivaras; Mazeika, Kestutis; Baltrunas, Dalis

    2017-01-01

    The magnetic nanosized rare earth iron garnets (R_3Fe_5O_1_2, where R=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared by an aqueous sol–gel method. Herein we present, that all these garnets can be obtained by this effective synthesis method simply by changing the temperature of the final annealing. It was also demonstrated, that a different annealing temperature leads to a different particle size distribution of the final product. The SEM analysis results revealed that the smallest particles were formed in the range of 75–130 nm. The phase purity and structure of the rare earth iron garnets were estimated using XRD analysis and Mössbauer spectroscopy. Magnetic properties were determined by magnetization measurements. The relation between the particle size, composition and magnetic properties of the sol-gel derived garnets were also discussed in this study. - Highlights: • First time series of R_3Fe_5O_1_2 (R=from Sm to Lu) are prepared by sol–gel process. • Different sintering temperature leads to the different particle size distribution. • Correlation between microstructure, composition and magnetic properties is shown.

  6. Rare earth germanates

    International Nuclear Information System (INIS)

    Bondar', I.A.; Vinogradova, N.V.; Dem'yanets, L.N.

    1983-01-01

    From the viewpoint of structural chemistry and general regularities controlling formation reactions of compounds and phases in melts, solid and gaseous states, recent achievements in the chemistry of rare earth germanates are generalized. Methods of synthesizing germanates, systems on the base of germanium oxides and rare earths are considered. The data on crystallochemical characteristics are tabulated. Individual compounds of scandium germanate are also characterized. Processes of germanate formation using the data of IR-spectroscopy, X-ray phase analysis are studied. The structure and morphotropic series of rare earth germanates and silicates are determined. Fields of their present and possible future application are considered

  7. Chemical analysis of rare earth elements

    International Nuclear Information System (INIS)

    Tsukahara, Ryoichi; Sakoh, Takefumi; Nagai, Iwao

    1994-01-01

    Recently attention has been paid to ICP-AES or ICP-MS, and the reports on the analysis of rare earth elements by utilizing these methods continue to increase. These reports have become to take about 30% of the reports on rare earth analysis, and this is because these methods are highly sensitive to rare earth elements, and also these methods have spread widely. In ICP-AES and ICP-MS, mostly solution samples are measured, therefore, solids must be made into solution. At the time of quantitatively determining the rare earth elements of low concentration, separation and concentration are necessary. Referring to the literatures reported partially in 1990 and from 1991 to 1993, the progress of ICP-AES and ICP-MS is reported. Rare earth oxides and the alloys containing rare earth elements are easily decomposed with acids, but the decomposition of rocks is difficult, and its method is discussed. The separation of the rare earth elements from others in geochemical samples, cation exchange process is frequently utilized. Also solvent extraction process has been studied. For the separation of rare earth elements mutually, chromatography is used. The spectral interference in spectral analysis was studied. The comparison of these methods with other methods is reported. (K.I)

  8. Microstructure and property evaluation of high-pressure die-cast Mg–La–rare earth (Nd, Y or Gd) alloys

    International Nuclear Information System (INIS)

    Gavras, Serge; Easton, Mark A.; Gibson, Mark A.; Zhu, Suming; Nie, Jian-Feng

    2014-01-01

    Highlights: • Different rare earth elements have remarkably different effects on Mg castability. • For the addition of each RE element, the alloy castability follows a unique pattern. • The effects of RE elements on the castability can be modelled. - Abstract: Microstructure, castability and tensile properties were investigated in high-pressure die-cast Mg–La–Nd, Mg–La–Y and Mg–La–Gd alloy series, with a constant La concentration at approximately 2.5 wt.% and the concentrations of Nd, Y or Gd were varied. All three alloy series had a dendritic microstructure with a Mg–La-rich eutectic with increasing Nd, Y or Gd content and containing a Mg 12 RE intermetallic phase. The morphology of the eutectic at ternary alloying additions of equal to or less than 1.0 wt.% was lamellar but became increasingly divorced at higher ternary concentrations. This was however more obvious in Mg–La–Y and Mg–La–Gd than Mg–La–Nd alloys. The hot tearing susceptibility in all three alloy series increased markedly with even micro-alloying additions of Nd, Y or Gd, and began to decrease again in alloys with more than 0.5 wt.% Y or 1.0 wt.% Gd, but did not decrease significantly for Mg–La–Nd. A model using the temperature–fraction solid curves as input parameters was used to estimate hot tearing susceptibility for Mg–La–Nd alloys. Tensile testing at room temperature showed that Mg–La–Nd alloy series had higher 0.2% proof stress and lower elongation to failure than either the Mg–La–Y or the Mg–La–Gd alloy series for Nd concentrations greater than 1 wt.% due to a greater effectiveness of grain boundary reinforcement

  9. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.C.

    1975-01-01

    A process is described for preparing novel sintered cobalt--rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties. A cobalt--rare earth metal alloy is formed having a composition which at sintering temperature falls outside the composition covered by the single Co 5 R intermetallic phase on the rare earth richer side. The alloy contains a major amount of the Co 5 R intermetallic phase and a second solid CoR phase which is richer in rare earth metal content than the Co 5 R phase. The specific cobalt and rare earth metal content of the alloy is substantially the same as that desired in the sintered product. The alloy, in particulate form, is pressed into compacts and sintered to the desired density. The sintered product is comprised of a major amount of the Co 5 R solid intermetallic phase and up to about 35 percent of the product of the second solid CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase

  10. The fractionation and geochemical characteristics of rare earth elements measured in ambient size-resolved PM in an integrated iron and steelmaking industry zone.

    Science.gov (United States)

    Dai, Qili; Li, Liwei; Yang, Jiamei; Liu, Baoshuang; Bi, Xiaohui; Wu, Jianhui; Zhang, YuFen; Yao, Lin; Feng, Yinchang

    2016-09-01

    Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due to the unclear atmospheric signature of these elements and their adverse impact on human health and the environment. In this study, ambient particulate matter of different sizes was collected from one site in an integrated iron and steelmaking industrial zone (HG) and one urban background site with no direct industrial emissions (ZWY) during a 1-year sampling campaign in China. The total concentrations of REEs for TSP, PM10, and PM2.5 were 27.248, 14.989, 3.542 ng/m(3) in HG and 6.326, 5.274, 1.731 ng/m(3), respectively, in ZWY, which revealed the local influence of the steelmaking activities to the air quality. With respect to ZWY, the REEs in HG site are obviously fractionated in the coarser fraction, and LREEs account for more than 80 % of the total REE burden in all of the samples. Additionally, the REEs in HG and ZWY show a homogeneous trend with successively increased LREE/HREE ratios from the coarse particles to the fine particles. In our samples, La, Ce, Nd, and Sm are the most enriched rare earth elements, especially in the HG site. Moreover, ternary diagrams of LaCeSm indicate that the REEs in HG are potentially contributed by steelworks, carrier vehicles, coal combustion, and road dust re-suspension.

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

    Science.gov (United States)

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

    2016-01-01

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

  12. A compounded rare-earth iron garnet single crystal exhibiting stable Faraday rotation against wavelength and temperature variation in the 1.55 μm band

    International Nuclear Information System (INIS)

    Xu, Z.C.; Huang, M.; Li Miao

    2006-01-01

    The Bi, Tb and Yb partially substituted iron garnet bulk single crystals of Tb 3- x - y Yb y Bi x Fe 5 O 12 were grown by using Bi 2 O 3 /B 2 O 3 as flux and accelerated crucible rotation technique for single-crystal growth. Faraday rotation (FR) spectra showed that the specific FR of the (Tb 0.91 Yb 1.38 Bi 0.71 )Fe 5 O 12 crystal under magnetic field at saturation was measured to be about -1617 o /cm at λ=1.55 μm, Faraday rotation wavelength coefficient (FWC, 0.009%/nm) in the wavelength range of 1.50-1.62 μm and Faraday rotation temperature coefficient (FTC, 3.92x10 -5 /K) at λ=1.55 μm were even smaller than that of YIG. It is proven that through combining two types of Bi-substituted rare-earth iron garnets with opposite FWC and FTC signs, the compound rare-earth iron garnets with low FWC and FTC may be obtained due to the compensation effect. The saturation magnetization of (Tb 0.91 Yb 1.38 Bi 0.71 ) Fe 5 O 12 crystal is 0.48x10 6 A/M and is also much smaller than that of YIG. We have found empirically that there is a simple relationship between the FR θ f (x) and Bi content x for Tb 3- x - y Yb y Bi x Fe 5 O 12 , which is given by θ f (x)=(-2759x+400) o /cm

  13. Recovery of rare earths from red mud

    International Nuclear Information System (INIS)

    Bautista, R.G.

    1992-01-01

    The prospect for the recovery of rare earths from red mud, the bauxite tailings from the production of alumina is examined. The Jamaican red mud by far has the higher trace concentrations of lanthanum, cerium, neodymium, and yttrium. Scandium is also present. The dissolution of the rare earth is a major extraction problem because of the large volume of other materials. The recovery processes that have been proposed include the production of co-products such as iron, alumina, and titanium concentrates, with the rare earths going with the titanium. In this paper a critical examination of the possible processes are presented with the recommended research projects to be carried out

  14. Evaluation of short-term effects of rare earth and other elements used in magnesium alloys on primary cells and cell lines.

    Science.gov (United States)

    Feyerabend, Frank; Fischer, Janine; Holtz, Jakob; Witte, Frank; Willumeit, Regine; Drücker, Heiko; Vogt, Carla; Hort, Norbert

    2010-05-01

    Degradable magnesium alloys for biomedical application are on the verge of being used clinically. Rare earth elements (REEs) are used to improve the mechanical properties of the alloys, but in more or less undefined mixtures. For some elements of this group, data on toxicity and influence on cells are sparse. Therefore in this study the in vitro cytotoxicity of the elements yttrium (Y), neodymium (Nd), dysprosium (Dy), praseodymium (Pr), gadolinium (Gd), lanthanum (La), cerium (Ce), europium (Eu), lithium (Li) and zirconium (Zr) was evaluated by incubation with the chlorides (10-2000 microM); magnesium (Mg) and calcium (Ca) were tested at higher concentrations (200 and 50mM, respectively). The influence on viability of human osteosarcoma cell line MG63, human umbilical cord perivascular (HUCPV) cells and mouse macrophages (RAW 264.7) was determined, as well as the induction of apoptosis and the expression of inflammatory factors (TNF-alpha, IL-1alpha). Significant differences between the applied cells could be observed. RAW exhibited the highest and HUCPV the lowest sensitivity. La and Ce showed the highest cytotoxicity of the analysed elements. Of the elements with high solubility in magnesium alloys, Gd and Dy seem to be more suitable than Y. The focus of magnesium alloy development for biomedical applications should include most defined alloy compositions with well-known tissue-specific and systemic effects. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  15. Inhibition of stress corrosion cracking of alloy AA8090 T-8171 by addition of rare earth salts

    International Nuclear Information System (INIS)

    Davo, B.; Conde, A.; Damborenea, J.J. de

    2005-01-01

    Aluminium-lithium alloys are suitable for aeronautical purposes because of their good mechanical properties and high damage tolerance. Although these alloys are less susceptible to stress corrosion cracking than conventional alloys, Al-Li-Cu-Mg alloy (8090-T8171) still experiences this problem in a NaCl + H 2 O 2 solution. In this work it has been demonstrated that the addition of 10,000 ppm of CeCl 3 to the medium inhibits the stress corrosion cracking of 8090 alloy by precipitation of cerium oxides/hydroxides. The deposition of these compounds on the alloy surface decreases the pit density and slows the crack growth through the grain boundaries by hindering the anodic dissolution of T phases

  16. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

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

  17. The Effects of Rare Earth Pr and Heat Treatment on the Wear Properties of AZ91 Alloy

    Directory of Open Access Journals (Sweden)

    Ning Li

    2018-06-01

    Full Text Available This paper investigated the influences of Pr addition and heat treatment (T6 on the dry sliding wear behavior of AZ91 alloy. The wear rates and friction coefficients were measured by using a pin-on-disc tribometer under loads of 30, 60 and 90 N at dry sliding speeds of 100 rpm, over a sliding time of 15 min. The worn surfaces were examined using a scanning electron microscope and was analyzed with an energy dispersive spectrometer. The experimental results revealed that AZ91-1.0%Pr magnesium alloy exhibited lower wear rate and friction coefficient than the other investigated alloys. As the applied load increased, the wear rate and friction coefficient increased. Compared with the as-cast AZ91-1.0%Pr magnesium alloy, the hardness and wear resistance of the alloy after solution treatment were reduced, and through the subsequent aging, the hardness and wear resistance of the alloy were improved and the hardness was 101.1 HB (compared to as-cast AZ91 magnesium alloy, it increased by 45%. The AZ91-1.0%Pr with T6 magnesium alloy exhibited best wear resistance. Abrasion was dominant at load of 30 N, delamination was dominant at load of 60 N and plastic deformation was dominant at load of 90 N. Oxidation was observed at all loads.

  18. Influence of rare earth additions on the oxidation resistance of chromia forming alloys; Influencia da adicao de terras raras sobre a resistencia a oxidacao de ligas formadoras de cromia

    Energy Technology Data Exchange (ETDEWEB)

    Pillis, Marina Fuser

    1995-12-31

    The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O{sub 2} and AISI 316L+Y{sub 2} O{sub 3} by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O{sub 2} to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O{sub 3}. The isothermal oxidation behavior of rare earth oxide covered

  19. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  20. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

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

    1991-01-01

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

  1. Contributions to the rare earths to science and technology

    International Nuclear Information System (INIS)

    Spedding, F.H.

    1975-01-01

    This is a brief summary of some areas of science where the rare earths have already played an important role and of other areas where they are almost certain to be helpful. The discovery, abundance, separation, and properties of rare earths are discussed. It is pointed out that the rare earths comprise almost one-fourth of the known metals, and their alloys a third of the possible alloys

  2. Effect of Rare Earth on Corrosion Products and Impedance Behavior of AZ91 Magnesium Alloy Under Dry-wet Cycles

    Directory of Open Access Journals (Sweden)

    ZHAO Xi

    2017-04-01

    Full Text Available The effect of mischmetal of lanthanum and cerium on the composition and structure of the corrosion products on the surface of AZ91 Mg alloy in deicing salt solution under dry-wet cycles was investigated by scanning electron microscopy (SEM, X-ray diffraction (XRD and energy dispersive spectrometer (EDS. The results show that the corrosion products of AZ91 Mg alloy without mischmetal addition (La,Ce are mainly composed of Mg(OH2, MgO, CaCO3 and Mg6Al2CO3(OH16·4H2O; and (La,CeAlO3 can be found in the products of AZ91 with mischmetal addition, meanwhile dense layer occurs in the corrosion products. Electrochemical impedance spectroscopy (EIS measurements show that the charge transfer resistance of AZ91 alloy with mischmetal addition tested in the same dry-wet cycles is much higher than that of AZ91 alloy, the addition of mischmetal helps to reduce the dispersing effect of impedance spectroscopy, indicating that the corrosion resistance of AZ91 Mg alloy and the stability of corrosion product films can be improved by mischmetal of La and Ce.

  3. Design, processing and characterization of mechanically alloyed galfenol & lightly rare-earth doped FeGa alloys as smart materials for actuators and transducers

    Science.gov (United States)

    Taheri, Parisa

    Smart materials find a wide range of application areas due to their varied response to external stimuli. The different areas of application can be in our day to day life, aerospace, civil engineering applications, and mechatronics to name a few. Magnetostrictive materials are a class of smart materials that can convert energy between the magnetic and elastic states. Galfenol is a magnetostrictive alloy comprised primarily of the elements iron (Fe) and gallium (Ga). Galfenol exhibits a unique combination of mechanical and magnetostrictive (magnetic) properties that legacy smart materials do not. Galfenol's ability to function while in tension, mechanical robustness and high Curie temperature (600 °C) is attracting interest for the alloy's use in mechanically harsh and elevated temperature environments. Applications actively being investigated include transducers for down-hole use, next-generation fuel injectors, sensing, and energy harvesting devices. Understanding correlations between microstructure, electronic structure, and functional response is key to developing novel magnetostrictive materials for sensor and actuator technologies. To this end, in the first part of this thesis we report successful fabrication and investigation of magnetic and magnetostrictive properties of mechanically alloyed Fe81Ga19 compounds. For the first time, we could measure magnetostrictive properties of mechanically alloyed FeGa compounds. A maximum saturation magnetostriction of 41 ppm was achieved which is comparable to those measured from polycrystalline FeGa alloys prepared by other processing techniques, namely gas atomization and cold rolling. Overall, this study demonstrates the feasibility of large-scale production of FeGa polycrystalline alloys powders by a simple and cost-effective mechanical alloying technique. In the second part of this work, we report for the first time, experimental results pertaining to successful fabrication and advanced characterization of a series

  4. Obtained of magnetic alloys at base of rare earths-transition metals (4f/3d) by calciothermal reduction

    International Nuclear Information System (INIS)

    Paschoal, J.O.A.; Lima, L.F.C.P. de; Faria Junior, R.N.; Monzani, D.; Takiishi, H.; Caldas, S.H.R.; Gulherme, E.G.; Carvalho, P.A.; Acevedo, M.T.

    1989-01-01

    The phases of preparation of powder of the alloys Sm-Co and Nd-Fe-B are studied. These phases were developed and optimized like part of the permanent magnet program of the Energetic and Nuclear Research Institute (IPEN), in Brazil, that has the objective of obtain magnets of high product of energy (BxH). (V.R.B.)

  5. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

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

  6. Rapid analysis of some rare earth magnets

    International Nuclear Information System (INIS)

    Raoot, K.N.; Raoot, Sarala; Rukmani Desikan, N.

    1978-01-01

    A simple complexometric method for the quick analysis of the constituent elements in some quaternary rare earth magnets of the type RE-Co-Cu-Fe and RE-Ni-Cu-Fe is described. The technique is based on a total titration, subsequent release of EDTA from rare earth with ammonium fluoride and that from copper (II) with ascorbic acid and thiourea followed by determination of the excess and liberated EDTA by lead nitrate in a weak acid medium using xylenol orange indicator. In another, aliquot iron (III) and rare earth are first masked with sodium fluoride, and copper (II) with ascorbic acid and thiourea before cobalt (II) or nickel (II) is estimated by back titration. Iron is calculated by difference. The new method yields accurate and reproducible results with error not exceeding 1%. A set of three samples can conveniently be analysed in two hours. (author)

  7. Rapid analysis of some rare earth magnets

    Energy Technology Data Exchange (ETDEWEB)

    Raoot, K N; Raoot, S; Rukmani Desikan, N [Defence Metallurgical Research Lab., Hyderabad (India)

    1978-12-01

    A simple complexometric method for the quick analysis of the constituent elements in some quaternary rare earth magnets of the type RE-Co-Cu-Fe and RE-Ni-Cu-Fe is described. The technique is based on a total titration, subsequent release of EDTA from rare earth with ammonium fluoride and that from copper (II) with ascorbic acid and thiourea followed by determination of the excess and liberated EDTA by lead nitrate in a weak acid medium using xylenol orange indicator. In another, aliquot iron (III) and rare earth are first masked with sodium fluoride, and copper (II) with ascorbic acid and thiourea before cobalt (II) or nickel (II) is estimated by back titration. Iron is calculated by difference. The new method yields accurate and reproducible results with error not exceeding 1%. A set of three samples can conveniently be analysed in two hours.

  8. Controlling laser-induced magnetization reversal dynamics in a rare-earth iron garnet across the magnetization compensation point

    Science.gov (United States)

    Deb, Marwan; Molho, Pierre; Barbara, Bernard; Bigot, Jean-Yves

    2018-04-01

    In this work we explore the ultrafast magnetization dynamics induced by femtosecond laser pulses in a doped film of gadolinium iron garnet over a broad temperature range including the magnetization compensation point TM. By exciting the phonon-assisted 6S→4G and 6S→4P electronic d -d transitions simultaneously by one- and two-photon absorption processes, we find out that the transfer of heat energy from the lattice to the spin has, at a temperature slightly below TM, a large influence on the magnetization dynamics. In particular, we show that the speed and the amplitude of the magnetization dynamics can be strongly increased when increasing either the external magnetic field or the laser energy density. The obtained results are explained by a magnetization reversal process across TM. Furthermore, we find that the dynamics has unusual characteristics which can be understood by considering the weak spin-phonon coupling in magnetic garnets. These results open new perspectives for controlling the magnetic state of magnetic dielectrics using an ultrashort optically induced heat pulse.

  9. Textures and mechanical properties in rare-earth free quasicrystal reinforced Mg-Zn-Zr alloys prepared by extrusion

    International Nuclear Information System (INIS)

    Ohhashi, S.; Kato, A.; Demura, M.; Tsai, A.P.

    2011-01-01

    Highlights: → Powder-metallurgical warm extrusion made quasicrystal dispersing Mg alloys. → Mg extrusions containing quasicrystals showed randomized textures. → These extrusion showed the enhancement of mechanical properties at 150 deg. C. - Abstract: Microstructure and mechanical properties of quasicrystals dispersed Mg alloys prepared by warm extrusion of the mixtures of Mg and Zn-Mg-Zr quasicrystalline (Qc) powders have been studied. Strong texture oriented along a [101-bar 0] direction observed in pure Mg was reduced in Qc-dispersed samples, as verified by pole figure method and electron back scattering diffraction. The ultimate tensile strengths at 150 deg. C for Qc-dispersed extrusions were much higher than 110 MPa for pure Mg, which drastically reached 156 MPa for 15 wt.% Qc by preventing the motion of dislocations. Elongation was improved by the randomization of grain orientation: from 5.7% for pure Mg to 12.9% for 10 wt.% Qc at room temperature; from 15% for pure Mg to 37.1% for 5 wt.% Qc at 150 deg. C.

  10. Separation and Recovery of Iron and Rare Earth from Bayan Obo Tailings by Magnetizing Roasting and (NH42SO4 Activation Roasting

    Directory of Open Access Journals (Sweden)

    Yan Zhou

    2017-05-01

    Full Text Available A novel approach for recovery of iron and rare earth elements (REEs from Bayan Obo tailings of Baotou, China, was developed by combining magnetizing roasting, magnetic separation, (NH42SO4 activation roasting, and water leaching. Thermodynamic analysis of carbothermal reduction was conducted to determine the temperature of magnetizing roasting, and it agreed well with the experimental results. The maximum recovery of Fe reached 77.8% at 600 °C, and the grade of total Fe in the magnetic concentrate was 56.3 wt. %. An innovative approach, using water to leach REEs after (NH42SO4 activation roasting, was used to extract REEs from magnetic separation tailings. The main influence factors of the leaching recovery during (NH42SO4 activation roasting, were investigated with the mass ratio of (NH42SO4 to magnetic separation tailings, roasting temperature and roasting time. The leaching recoveries of La, Ce and Nd reached 83.12%, 76.64% and 77.35%, respectively, under the optimized conditions: a mass ratio of 6:1, a roasting temperature of 400 °C and a roasting time of 80 min. Furthermore, the phase composition and reaction process during the (NH42SO4 activation roasting were analyzed with X-ray diffraction (XRD, energy dispersive X-ray spectroscopy & scanning electron microscopy (EDS-SEM and thermogravimetry & differential scanning calorimetry (TG-DSC, and the leaching solution and leaching residue were also characterized.

  11. Clinical evaluation of neodymium-iron-boron (Ne2Fe14B) rare earth magnets in the treatment of mid line diastemas

    Science.gov (United States)

    Manoj-Kumar, Mitta; Gowri-Sankar, Singaraju; Chaitanya, Nellore; Vivek-Reddy, Ganugapanta; Venkatesh, Nettam

    2016-01-01

    Background To evaluate the closure of midline diastema using the Neodymium-Iron-Boron magnets and to compare the treatment duration of midline diastemas with the use of magnets compared to regular orthodontic treatment. Material and Methods Thirty patients with age group 12 to 30 years with the midline diastema ranging from 0.5 to 3mm were selected. These patients were divided into two groups. Diastema closure in one group was accomplished by conventional method, in other group was done with Ne2Fe14B magnets. These magnets were fitted to the labial surfaces of the maxillary central incisors such a way that the opposite poles of the magnets face each other. At each appointment, study models and radiographs were taken for study subjects and the midline diastema was measured using digital vernier calipers on the study models obtained. Descriptive statistics carried out using Paired t-test. Results Subjects treated with Ne2Fe14B magnets showed a significant difference compared to fixed orthodontic appliance subjects with respect to time of closure, rate of space closure and incisal inclination. Significant difference between 2 groups with reduction of 64.6 days in time to diastema closure in subjects treated with Ne2Fe14B magnets (Pclosure of mid line diastema in less duration of time. Key words:Midline diastema, Ne2Fe14B magnets, rare earth magnets, space closure. PMID:27034757

  12. Rare Earth Polyoxometalates.

    Science.gov (United States)

    Boskovic, Colette

    2017-09-19

    Longstanding and important applications make use of the chemical and physical properties of both rare earth metals and polyoxometalates of early transition metals. The catalytic, optical, and magnetic features of rare earth metal ions are well-known, as are the reversible multielectron redox and photoredox capabilities of polyoxomolybdates and polyoxotungstates. The combination of rare earth ions and polyoxometalates in discrete molecules and coordination polymers is of interest for the unique combination of chemical and physical properties that can arise. This Account surveys our efforts to synthesize and investigate compounds with rare earth ions and polyoxometalates (RE-POMs), sometimes with carboxylate-based organic coligands. Our general synthetic approach is "bottom-up", which affords well-defined nanoscale molecules, typically in crystalline form and amenable to single-crystal X-ray diffraction for structure determination. Our particular focus is on elucidation of the physical properties conferred by the different structural components with a view to ultimately being able to tune these properties chemically. For this purpose, we employ a variety of spectroscopic, magnetochemical, electrochemical, and scattering techniques in concert with theoretical modeling and computation. Studies of RE-POM single-molecule magnets (SMMs) have utilized magnetic susceptibility, inelastic neutron scattering, and ab initio calculations. These investigations have allowed characterization of the crystal field splitting of the rare earth(III) ions that is responsible for the SMM properties of slow magnetic relaxation and magnetization quantum tunneling. Such SMMs are promising for applications in quantum computing and molecular spintronics. Photophysical measurements of a family of hybrid RE-POMs with organic ligands have afforded insights into sensitization of Tb(III) and Eu(III) emission through both organic and polyoxometalate chromophores in the same molecule. Detailed

  13. Non-rare earth magnetic nanoparticles

    Science.gov (United States)

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

    2017-09-26

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

  14. A first-principles study of B2 NiAl alloyed with rare earth elements Pr, Pm, Sm, and Eu

    Institute of Scientific and Technical Information of China (English)

    He Jun-Qi; Wang You; Yan Mu-Fu; Pan Zhao-Yi; Guo Li-Xin

    2013-01-01

    The structural,elastic,and electronic properties of NiAl alloyed with rare earth elements Pr,Pm,Sm,and Eu are investigated by using density functional theory (DFT).The study suggests that Pr,Pm,Sm,and Eu all tend to be substituted for an Al site.Ni8Al7Pm possesses the largest ductility.Only the hardness and ductility of Ni8Al7Eu are enhanced simultaneously.The covalency strength of the Ni-Al bond in Ni8Al7Pm is higher than that in Ni8Al7Eu.The covalency strength of an Al-Al bond and that of a Ni-Ni bond in Ni8Al7Eu are higher than that in Ni8Al7Pm.The Ni-Pm bond and the Ni-Eu bond are covalent,and the covalency strength of the Ni-Pm bond is greater.The Al-Pm bond and the Al-Eu bond show great covalency strength and ionicity,respectively.

  15. Thermogravimetric study of rare earth concentrates

    International Nuclear Information System (INIS)

    Delyagejd, V.V.; Anisimova, V.N.; Eremenko, Z.V.; Kutsev, V.S.

    1974-01-01

    Methods of thermogravimetric, chemical and phase analysis were used in measuring the concentration of rare-earth elements of different origins. At temperatures 400-800 deg C a gradual decomposition of fluorocarbonates takes place leading to the formation of derivatives of corresponding oxides and oxyfluorides. For concentrates containing siderite the process takes place at 550-600 deg C followed by oxidation of bivalent iron into trivalent state. Reaction of rare-earth elements with sodium carbonate and the increase in the concentration of the latter results in a narrowing down of the interval of temperatures at which decomposition takes place. Under these conditions an intense reaction and a fusion take place leading to the formation of eutectic at 500-600 deg C and further synthesis of sodium fluoride and oxyfluoride derivatives of calcium and rare-earth elements

  16. Rare earth superlattices

    International Nuclear Information System (INIS)

    McMorrow, D.F.

    1997-01-01

    A review is given of recent experiments on the magnetism of rare earth superlattices. Early experiments in this field were concerned mainly with systems formed by combining a magnetic and a non-magnetic element in a superlattice structure. From results gathered on a variety of systems it has been established that the propagation of magnetic order through the non-magnetic spacer can be understood mostly on the basis of an RKKY-like model, where the strength and range of the coupling depends on the details of the conduction electron susceptibility of the spacer. Recent experiments on more complex systems indicate that this model does not provide a complete description. Examples include superlattices where the constituents can either be both magnetic, adopt different crystal structures (Fermi surfaces), or where one of the constituents has a non-magnetic singlet ground state. The results from such systems are presented and discussed in the context of the currently accepted model. (au)

  17. Rare earth (3) pivalates

    International Nuclear Information System (INIS)

    Kuz'mina, N.P.; Martynenko, L.I.; Zoan An' Tu; Ch'eu Tkhi Nguet; Troyanov, S.I.; Rykov, A.N.; Korenev, Yu.M.

    1994-01-01

    Depending on synthesis conditions rare earth pivalates can be obtained in the form of either adducts NPiv·HPiv or hydrates MPiv 3 ·mH 2 O. Adducts are the most stable form of pivalates. Heating of adducts result in formation of corresponding MPiv 3 . MPiv 3 ·nHPiv compounds are characterized by IR-spectroscopy and thermal analysis data. Behaviour of MPiv 3 was studied in the regime of vacuum sublemation. Using mass spectroscopy of NdPiv 3 it was shown that gaseous phase above MPiv 3 had complex composition and contained ligomer fragments. X-ray structure analysis of [NdPiv 3 ·3HPiv] was conducted

  18. Microstructure and properties of the low-power-laser clad coatings on magnesium alloy with different amount of rare earth addition

    International Nuclear Information System (INIS)

    Zhu, Rundong; Li, Zhiyong; Li, Xiaoxi; Sun, Qi

    2015-01-01

    Highlights: • The low-power-laser was used to obtain the excellent coatings with different amount of Y_2O_3 addition. • The addition of rare earth oxide Y_2O_3 refined and purified the microstructure of the coatings, meanwhile, increased the thickness of the coatings and reduced the dilution of cladding materials from based alloy. • The primary phases in the coatings are Mg_3_2Al_4_7Cu_7, MgCu_6Al_5, Al_2CuMg and Al_1_2Mg_1_7. The A_l_4MgY and MgAl_2O_4 phase can be found in Y_2O_3-modified coatings. • The micro-hardness and the abrasion resistance of the coatings with Y_2O_3 had been improved obviously compared with the coatings without Y_2O_3. • The corrosion resistance of the AZ91D magnesium alloy had been improved by laser cladding. And the effect of Y_2O_3 on the corrosion potential of the coatings was less than the effect of Y_2O_3 on corrosion current density of the coatings. - Abstract: Due to the low-melting-point and high evaporation rate of magnesium at elevated temperature, high power laser clad coating on magnesium always causes subsidence and deterioration in the surface. Low power laser can reduce the evaporation effect while brings problems such as decreased thickness, incomplete fusion and unsatisfied performance. Therefore, low power laser with selected parameters was used in our research work to obtain Al–Cu coatings with Y_2O_3 addition on AZ91D magnesium alloy. The addition of Y_2O_3 obviously increases thickness of the coating and improves the melting efficiency. Furthermore, the effect of Y_2O_3 addition on the microstructure of laser clad Al–Cu coatings was investigated by scanning electron microscopy. The energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to examine the elemental and phase compositions of the coatings. The properties were investigated by micro-hardness test, dry wear test and electrochemical corrosion. It was found that the addition of Y_2O_3 refined the microstructure. The micro

  19. Method for producing dysprosium-iron-boron alloy powder

    International Nuclear Information System (INIS)

    Camp, F.E.; Wooden, S.A.

    1989-01-01

    A method for producing a dysprosium-iron alloy adapted for use in the manufacture of rare-earth element containing, iron-boron permanent magnets, the method including providing a particle mixture comprising dysprosium oxide, iron and calcium, compacting the particle mixture to produce a consolidated article, heating the article for a time at temperature to form a metallic compound comprising dysprosium and iron and to form calcium oxide, producing a particle mass of -35 mesh from the compact, washing the particle mass with water at a temperature no greater than 10 0 C to react to the calcium and to the calcium oxide therewith to form a calcium hydroxide, while preventing oxidation of the particle mass, and removing the calcium hydroxide from the particle mass

  20. China's rare-earth industry

    Science.gov (United States)

    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.

  1. Mechanism of the high transition temperature for the 1111-type iron-based superconductors R FeAsO (R =rare earth ): Synergistic effects of local structures and 4 f electrons

    Science.gov (United States)

    Zhang, Lifang; Meng, Junling; Liu, Xiaojuan; Yao, Fen; Meng, Jian; Zhang, Hongjie

    2017-07-01

    Among the iron-based superconductors, the 1111-type Fe-As-based superconductors REFeAs O1 -xFx (RE = rare earth) exhibit high transition temperatures (Tc) above 40 K. We perform first-principles calculations based on density functional theory with the consideration of both electronic correlations and spin-orbit couplings on rare earths and Fe ions to study the underlying mechanism as the microscopic structural distortions in REFeAsO tuned by both lanthanide contraction and external strain. The electronic structures evolve similarly in both cases. It is found that there exist an optimal structural regime that will not only initialize but also optimize the orbital fluctuations due to the competing Fe-As and Fe-Fe crystal fields. We also find that the key structural features in REFeAsO, such as As-Fe-As bond angle, intrinsically induce the modification of the Fermi surface and dynamic spin fluctuation. These results suggest that the superconductivity is mediated by antiferromagnetic spin fluctuations. Simultaneously, we show that the rare-earth 4 f electrons play important roles on the high transition temperature whose behavior might be analogous to that of the heavy-fermion superconductors. The superconductivity of these 1111-type iron-based superconductors with high-Tc is considered to originate from the synergistic effects of local structures and 4 f electrons.

  2. The Redox Dynamics of Iron in a Seasonally Waterlogged Forest Soil (Chaux Forest, Eastern France) Traced with Rare Earth Element Distribution Patterns

    Science.gov (United States)

    Steinmann, M.; Floch, A. L.; Lucot, E.; Badot, P. M.

    2014-12-01

    The oxyhydroxides of iron are common soil minerals and known to control the availability of various major and trace elements essential for biogeochemical processes. We present a study from acidic natural forest soils, where reducing redox conditions due to seasonal waterlogging lead to the dissolution of Fe-oxyhydroxides, and to the release of Fe to soil water. In order to study in detail the mechanism of redox cycling of Fe, we used Rare Earth Element (REE) distribution patterns, because an earlier study has shown that they are a suitable tool to identify trace metal sources during soil reduction in wetland soils (Davranche et al., 2011). The REE patterns of soil leachates obtained with the modified 3-step BCR extraction scheme of Rauret et al., (1999) were compared with those of natural soil water. The adsorbed fractions (F1 leach), the reducible fraction of the deepest soil horizon H4 (F2 leach, 50-120 cm), and the oxidizable fractions of horizons H2 to H4 (F3 leachs, 24-120 cm) yielded REE patterns almost identical to soil water (see figure), showing that the REE and trace metal content of soil water was mainly derived from the F1 pool, and from the F2 and F3 pools of the clay mineral-rich deep soil horizons. In contrast, the F2 leach mobilized mainly Fe-oxyhydroxides associated with organic matter of the surface soil and yielded REE patterns significantly different from those of soil water. These results suggest that the trace metal content of soil water in hydromorphic soils is primarily controlled by the clay fraction of the deeper soil horizons and not by organic matter and related Fe-oxyhydroxides of the surface soil. Additional analyses are in progress in order to verify whether the REE and trace metals of the deeper soil horizons were directly derived from clay minerals or from associated Fe-oxyhydroxide coatings. Refs cited: Davranche et al. (2011), Chem. Geol. 284; Rauret et al. (1999), J. Environ. Monit. 1.

  3. Progress of sintered NdFeB permanent magnets by the diffusion of non-rare earth elements and their alloy compounds

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available It has been found that the coercivity (HC and corrosivity of sintered NdFeB magnets are closely related to the components and microstructure of their intergranular phase.The traditional smelting NdFeB magnets with adding heavy rare earth elements can modify intergranular phase to improve the HC and corrosion resistance of magnets.However,it makes the additives be homogenously distributed on the main phase,and causes magnetic decrease and cost increase.With the addition of non-rare earth materials into grain boundary,the microstructure of intergranular phase as well as its electrochemical potential and wettability can be optimized.As a result,the amount of heavy rare earth elements and cost of magnets could be reduced whilst the HC and corrosion resistance of magnets can be improved.This paper summarized the research on regulating the components and the microstructure of intergranular phase in sintered NdFeB magnets by non-rare earth metals and compounds,and its influence on coercivity and corrosion resistance.

  4. Microstructure and properties of the low-power-laser clad coatings on magnesium alloy with different amount of rare earth addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Rundong; Li, Zhiyong, E-mail: lizhiyong@nuc.edu.cn; Li, Xiaoxi; Sun, Qi

    2015-10-30

    Highlights: • The low-power-laser was used to obtain the excellent coatings with different amount of Y{sub 2}O{sub 3} addition. • The addition of rare earth oxide Y{sub 2}O{sub 3} refined and purified the microstructure of the coatings, meanwhile, increased the thickness of the coatings and reduced the dilution of cladding materials from based alloy. • The primary phases in the coatings are Mg{sub 32}Al{sub 47}Cu{sub 7}, MgCu{sub 6}Al{sub 5}, Al{sub 2}CuMg and Al{sub 12}Mg{sub 17}. The A{sub l4}MgY and MgAl{sub 2}O{sub 4} phase can be found in Y{sub 2}O{sub 3}-modified coatings. • The micro-hardness and the abrasion resistance of the coatings with Y{sub 2}O{sub 3} had been improved obviously compared with the coatings without Y{sub 2}O{sub 3}. • The corrosion resistance of the AZ91D magnesium alloy had been improved by laser cladding. And the effect of Y{sub 2}O{sub 3} on the corrosion potential of the coatings was less than the effect of Y{sub 2}O{sub 3} on corrosion current density of the coatings. - Abstract: Due to the low-melting-point and high evaporation rate of magnesium at elevated temperature, high power laser clad coating on magnesium always causes subsidence and deterioration in the surface. Low power laser can reduce the evaporation effect while brings problems such as decreased thickness, incomplete fusion and unsatisfied performance. Therefore, low power laser with selected parameters was used in our research work to obtain Al–Cu coatings with Y{sub 2}O{sub 3} addition on AZ91D magnesium alloy. The addition of Y{sub 2}O{sub 3} obviously increases thickness of the coating and improves the melting efficiency. Furthermore, the effect of Y{sub 2}O{sub 3} addition on the microstructure of laser clad Al–Cu coatings was investigated by scanning electron microscopy. The energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to examine the elemental and phase compositions of the coatings. The properties were investigated

  5. Corrosion resistance of chromium-nickel steel containing rare earths

    International Nuclear Information System (INIS)

    Asatiani, G.N.; Mandzhgaladze, S.N.; Tavadze, L.F.; Chuvatina, S.N.; Saginadze, D.I.

    1983-01-01

    Effect of additional out-of-furnace treatment with complex alloy (foundry alloy) calcite-silicon-magnesium-rare earth metal on corrosion resistance of the 03Kh18N20M3D3C3B steel has been studied. It is shown that introduction of low additions of rare earths improves its corrosion resistance improves its corrosion resistance in agressive media (in 70% - sulfuric acid) in the range of transition from active to passive state. Effect of additional introduction of rare earth metals is not considerable, if potential of steel corrosion is in the range of stable passive state (32% - sulfuric acid). Additional out-of-furnace treatment with complex foundry alloy, containing rare earth metals, provides a possibility to use a steel with a lower content of Cr, Ni, Mo, than in conventional acid-resistant steels in highly agressive media

  6. Rare earth permanent magnets

    International Nuclear Information System (INIS)

    Higuchi, Akira

    1992-01-01

    This paper is a review of the new technologies for Nd-Fe-B magnets, their markets and future perspectives. This type of magnet is a product approaching the ideal magnet, and is based upon the development history of two previous generations of Sm-Co alloy systems and the recent progress on physical and metallurgical research. (orig.)

  7. Rare earths: critical elements for various applications and challenges in their separation

    International Nuclear Information System (INIS)

    Singh, D.K.; Chakravartty, J.K.

    2015-01-01

    High purity rare earths oxides, metal and alloys find wide applications in high tech area such as nuclear energy, permanent magnets, materials for storing hydrogen, phosphors, laser, etc. Rare earths consists a group of 15 elements from La to Lu in the periodic table and it also includes Sc and Y. Due to similar chemical nature owing to common oxidation state of +3, rare earths are very difficult to separate from each other. They have very low separation factors with acidic extractants like D2EHPA and EHEHPA and hence require large number of stages in various cascade of extraction process. Monazite (a source of rare earths, thorium and uranium) is processed at IREL to separate rare earths from thorium and uranium. The rare earths are fractionated into three groups namely light rare earths (LRE), middle rare earths (MRE) and heavy rare earths (HRE) by solvent extraction method employing EHEHPA as extractant

  8. Rare earth metals, rare earth hydrides, and rare earth oxides as thin films

    International Nuclear Information System (INIS)

    Gasgnier, M.

    1980-01-01

    The review deals with pure rare earth materials such as rare earth metals, rare earth hydrides, and rare earth oxides as thin films. Several preparation techniques, control methods, and nature of possible contaminations of thin films are described. These films can now be produced in an extremely well-known state concerning chemical composition, structure and texture. Structural, electric, magnetic, and optical properties of thin films are studied and discussed in comparison with the bulk state. The greatest contamination of metallic rare earth thin films is caused by reaction with hydrogen or with water vapour. The compound with an f.c.c. structure is the dihydride LnH 2 (Ln = lanthanides). The oxygen contamination takes place after annealing at higher temperatures. Then there appears a compound with a b.c.c. structure which is the C-type sesquioxide C-Ln 2 O 3 . At room atmosphere dihydride light rare earth thin films are converted to hydroxide Ln(OH) 3 . For heavy rare earth thin films the oxinitride LnNsub(x)Osub(y) is observed. The LnO-type compound was never seen. The present review tries to set the stage anew for the investigations to be undertaken in the future especially through the new generations of electron microscopes

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

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

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

  10. Rare earth industries: Downstream business

    International Nuclear Information System (INIS)

    2011-01-01

    The value chain of the rare earths business involves mining, extraction, processing, refining and the manufacture of an extensive range of downstream products which find wide applications in such industries including aerospace, consumer electronics, medical, military, automotive, renewable wind and solar energy and telecommunications. In fact the entire gamut of the high-tech industries depends on a sustainable supply of rare earths elements. The explosive demand in mobile phones is an excellent illustration of the massive potential that the rare earths business offers. In a matter of less than 20 years, the number of cell phones worldwide has reached a staggering 5 billion. Soon, going by the report of their growth in sales, the world demand for cell phones may even exceed the global population. Admittedly, the rare earths business does pose certain risks. Top among the risks are the health and safety risks. The mining, extraction and refining of rare earths produce residues and wastes which carry health and safety risks. The residues from the extraction and refining are radioactive, while their effluent waste streams do pose pollution risks to the receiving rivers and waterways. But, as clearly elaborated in a recent report by IAEA experts, there are technologies and systems available to efficiently mitigate such risks. The risks are Rare Earth manageable. However, it is crucial that the risk and waste management procedures are strictly followed and adhered to. This is where effective monitoring and surveillance throughout the life of all such rare earths facilities is crucial. Fortunately, Malaysia's regulatory standards on rare earths follow international standards. In some areas, Malaysia's regulatory regime is even more stringent than the international guidelines. (author)

  11. Safety aspects in rare earths recovery

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2014-01-01

    Recovery of rare earths involves mining of beach sands, mineral separation to obtain monazite and its chemical processing to obtain rare earth composites. The composites are then subjected to further chemical treatment to obtain individual rare earths. Although the separated out rare earths are not radioactive, the process for recovery of rare earths involve both radiological as well as conventional hazards. This paper highlights the safety aspects in the mining, mineral separation and chemical processing of monazite to obtain rare earths

  12. Electronic structure and properties of rare earth and actinide intermetallics

    International Nuclear Information System (INIS)

    Kirchmayr, H.R.

    1984-01-01

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

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

    Science.gov (United States)

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

    2016-01-01

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

  14. Influence of iron substitution by selected rare-earth ions on the properties of NiZn ferrite fillers and PVC magneto-polymer composites

    Science.gov (United States)

    Ušák, Elemír; Ušáková, Mariana; Dosoudil, Rastislav; Šoka, Martin; Dobročka, Edmund

    2018-04-01

    Nickel-zinc ferrites are very important soft magnetic materials from the point of view of diverse technical applications (such as, e.g., various electronic devices and components) for their high magnetic permeability and permittivity, low core loss, high resistivity, high Curie temperature as well as mechanical strength and chemical stability. Due to their good absorbing properties, they can be used as microwave absorbing and shielding materials with the aim of decreasing the environmental pollution caused by non-ionizing microwave radiation. The ferrite material incorporated into the polymer matrix creates qualitatively new magneto-polymer composite material taking benefits from both components. The properties typical for polymers (elasticity, mouldability, etc.) are combined with good high-frequency magnetic parameters, thus allowing to utilize these materials, e.g., in high-frequency applications where especially flexibility of composite materials plays a key role. Small amounts of selected rare-earth (RE) ions, in particular Y3+, La3+, Eu3+ and Gd3+ have been embedded into the nickel-zinc ferrite that has been used as the magnetic filler in magnetic polymer composites with polyvinylchloride (PVC) acting as the polymeric matrix. The effect of various types of rare-earth ions on the structural as well as quasi-static and dynamic (electro)magnetic properties of the ferrite fillers as well as ferrite/PVC composites, in particular the frequency dispersion of the complex permeability, has been studied.

  15. Rare earths as a future resource

    International Nuclear Information System (INIS)

    Cornell, D.H.

    1988-01-01

    The fourteen rare earth or lanthanide elements have recently emerged as an important natural resource because of the rapidly growing demand in the electronic, chemical and metallurgical industries. The Symposium on rare earth elements as a future resource presented a multidisciplinary review of rare earth chemistry, geology, beneficiation, industrial applications and marketing. Papers by experts in many fields were presented on the following topics: chemical properties of the rare earth elements; the analysis of rare earth elements and minerals; beneficiation and extraction of rare earth elements; economic geochemistry and mineralogy of rare earths; present industrial uses of rare earth elements; the role of rare earth elements in high-temperature superconductors; the technical application of high-temperature superconductors; supply and demand for rare earth products - now and in the future, and the geology of rare earth deposits

  16. Determination of trace impurities in iron-based alloy using neutron activation analysis

    International Nuclear Information System (INIS)

    Zaidi, J.H.; Waheed, S.; Ahmad, S.

    2000-01-01

    A radiochemical neutron activation analysis procedure has been developed and applied to investigate 40 major, minor, and trace impurities in iron-based alloy. A comparison of RNAA and INAA indicated a significant improvement in the detection limits. The extensive use of these alloys in the heavy mechanical industry, manufacturing of aircraft engines, nuclear applications, medical devices and chemical equipment requires their precise characterization. The concentration of iron in the iron-based alloy was found to be 86.7%, whereas Ca, Cr, K, Mg, Mn, V and W were the other constituents of the alloy, which constituted to around 12.89%. The rest of the elements were present in minor or trace levels. Most of the rare earth elements were also present in trace amounts. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-15

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

  18. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

    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

  19. Rare earth industries: Upstream business

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many factors contribute to the rush to invest in the unprecedented revival of rare earths. One major reason has to do with the rapidly growing world demand. The other reason relates to the attractive price of rare earths which is projected to stay strong in the coming years. This is because supply is predicted to have difficulty keeping pace with demand. Experts believe a major driver of global rare earths demand is the forecasted expansion in the green economy. Climate change is a major driver of the green economy. With climate change, there is concern that the uncontrolled emission of the greenhouse gases, especially carbon dioxide, can lead to catastrophic consequences for the world. This has been documented in countless studies and reports. Another important driver of the green economy is the growing shortfall in many resources. The world is now experiencing declines in key resources to meet a growing global demand. With more than 6 billion people now in the world and growing, the pressure exerted on global resources including energy, water and food is a major concern. Recent demand surge in China and India has dented the supply position of major world resources. The much quoted Stern Report from the UK has warned that, unless immediate steps are taken to reduce greenhouse gas emissions, it may be a costly exercise to undertake the corrections later. Since energy use, especially fossil fuels, is a major contributor to climate change, greener options are being sought. Add to that the fact that the fossil energy resources of the world are declining, the need to seek alternatives becomes even more urgent. One option is to change to renewable energy sources. These include such potentials as solar, wind and biomass. Rare earths have somehow become a critical feature of the technologies in such renewable. Another option is to improve the efficient use of energy in transport, buildings and all the other energy intensive industries. Again the technologies in

  20. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

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

  1. Handbook on the physics and chemistry of rare earths

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.; Eyring, L.

    1982-01-01

    This handbook is a six-volume work which covers the entire rare earth field in an integrated manner. Each chapter is a comprehensive, up-to-date, critical review of a particular segment of the field. The first volume is devoted to the rare earth metals, the second to rare earth alloys and intermetallics, and the third and fourth volumes to the non-metallic rare earth materials, including solutions, complexes and bioinorganic substances, in addition to solid inorganic compounds. The electronic structure of these unique elements is the primary basis of understanding their physical, metallurgical and chemical natures. The interrelationship of the 4f and valence electrons and the observed optical, electrical, magnetic, crystallographic, elastic, thermal, mechanical, chemical, geochemical and biological behaviors is brought forth time and again throughout the chapters. Also discussed are the preparative, separation and solution chemistry of the elements and their compounds and the various chemical and physical analytical methods for determining the rare earths in various materials and impurities in a rare earth matrix. Vol. 5 is a update complement of the previous volumes. Volume 6 is concerned with ternary and higher order materials. (Auth.)

  2. Extraction studies on rare earths using dinonyl phenyl phosphoric acid

    International Nuclear Information System (INIS)

    Anitha, M.; Singh, D.K.; Kotekar, M.K.; Vijayalakshmi, R.; Singh, H.

    2011-01-01

    Rare earths are widely used in phosphor materials, magnetic substances, alloys, catalyst, lasers, superconductors, solid oxide fuel cells and in nuclear applications. The high value of these elements depends on their effective separation into high purity compounds. The separation into individual rare earths is very difficult to achieve, due to the very low separation factors between two adjacent rare earths arising due to similar chemical properties. Taking the advantage of variation in basicity, the separation is generally accomplished by solvent extraction or ion exchange. There are several references on the separation of rare earth in different media employing various types of extractants such as 2-ethylhexyl 2-ethyhexylphosphonic acid (EHEHPA) and di-2-ethyl hexyl phosphoric acid (D2EHPA) which have been widely used for the separation and purification of rare earths. Dinonyl phenyl phosphoric acid (DNPPA) is an organo phosphorus extractant (pKa = 2.54) and is an aromatic analogue of D2EHPA, which extracts metal ion by cation exchange mechanism. DNPPA was explored to recover rare earths from phosphate media such as wet process phosphoric acid and merchant grade acid. However, there is no information available in literature on DNPPA for RE extraction from chloride medium. Therefore, an attempt has been made in the present study to investigate the feasibility of using DNPPA for extraction of La(III), Dy(III) and Y(III) from chloride medium

  3. Rare earth niobate coordination polymers

    Science.gov (United States)

    Muniz, Collin N.; Patel, Hiral; Fast, Dylan B.; Rohwer, Lauren E. S.; Reinheimer, Eric W.; Dolgos, Michelle; Graham, Matt W.; Nyman, May

    2018-03-01

    Rare-earth (RE) coordination polymers are infinitely tailorable to yield luminescent materials for various applications. Here we described the synthesis of a heterometallic rare-earth coordination compound ((CH3)2SO)3(RE)NbO(C2O4)3((CH3)2SO) = dimethylsulfoxide, DMSO, (C2O2= oxalate), (RE=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb). The structure was obtained from single crystal X-ray diffraction of the La analogue. The Nb˭O and DMSO terminal-bonding character guides assembly of an open framework structure with noncentrosymmetric RE-coordination geometry, and large spacing between the RE centers. A second structure was observed by PXRD for the smaller rare earths (Dy, Ho, Er, Yb); this structure has not yet been determined. The materials were further characterized using FTIR, and photoluminescence measurements. Characteristic excitation and emission transitions were observed for RE = Nd, Sm, Eu, and Tb. Quantum yield (QY) measurements were performed by exciting Eu and Tb analoges at 394 nm (QY 66%) and 464 nm (QY 71%) for Eu; and 370 nm (QY=40%) for Tb. We attribute the high QY and bright luminescence to two main structure-function properties of the system; namely the absence of water in the structure, and absence of concentration quenching.

  4. Rare earth industry in India

    International Nuclear Information System (INIS)

    Singh, D.S.

    2016-01-01

    Rare Earths (RE) comprises of 17 elements i.e. elements from atomic No. 57-71 (lanthanide series) along with yttrium (atomic No. 39) and scandium (atomic No. 21). They exhibit special electronic, magnetic, optical and catalytic properties. The first 7 elements in the lanthanide series from atomic Nos. 57 to 63 (La to Eu) are called Light Rare Earths (LRE), while the remaining elements from atomic Nos. 64 to 71 (Gd to Lu) are grouped as Heavy Rare Earths (HRE). Scandium and Yttrium have properties similar to HRE. The concentration of the REs in the earth's crust is as high as some other elements including that of copper. The only difference is that REs do not occur as separate minerals amenable for easy exploration and mining and are widely distributed across the earth's surface, hence they are called as REs. Resources In India, monazite has been the principal source of RE. It occurs in association with other heavy minerals, such as ilmenite, rutile, zircon etc. in the beach sands and inland placer deposits. The monazite content in this assemblage varies from negligible quantity to as high as 5%. As per AMD resource estimation, the reported resource of monazite in India is about 11.93 million tons which corresponds with about 6.9 million tons of RE oxides. Although India possesses large deposits of monazite, the heavier RE are not present in sufficient quantities in this mineral. (author)

  5. Iron-nickel-chromium alloys

    International Nuclear Information System (INIS)

    Karenko, M.K.

    1981-01-01

    A specification is given for iron-nickel-chromium age-hardenable alloys suitable for use in fast breeder reactor ducts and cladding, which utilize the gamma-double prime strengthening phase and are characterized in having a delta or eta phase distributed at or near grain boundaries. A range of compositions is given. (author)

  6. A combined neural network and mechanistic approach for the prediction of corrosion rate and yield strength of magnesium-rare earth alloys

    Energy Technology Data Exchange (ETDEWEB)

    Birbilis, N., E-mail: nick.birbilis@monash.ed [ARC Centre of Excellence for Design in Light Metals, Monash University (Australia); CAST Co-operative Research Centre, Monash University (Australia); Cavanaugh, M.K. [Department of Materials Science and Engineering, The Ohio State University (United States); Sudholz, A.D. [ARC Centre of Excellence for Design in Light Metals, Monash University (Australia); Zhu, S.M.; Easton, M.A. [CAST Co-operative Research Centre, Monash University (Australia); Gibson, M.A. [CSIRO Division of Process Science and Engineering (Australia)

    2011-01-15

    Research highlights: This study presents a body of corrosion data for a set of custom alloys and displays this in multivariable space. These alloys represent the next generation of Mg alloys for auto applications. The data is processed using an ANN model, which makes it possible to yield a single expression for prediction of corrosion rate (and strength) as a function of any input composition (of Ce, La or Nd between 0 and 6 wt.%). The relative influence of the various RE elements on corrosion is assessed, with the outcome that Nd additions can offer comparable strength with minimal rise in corrosion rate. The morphology and solute present in the eutectic region itself (as opposed to just the intermetallic presence) was shown - for the first time - to also be a key contributor to corrosion. The above approach sets the foundation for rational alloy design of alloys with corrosion performance in mind. - Abstract: Additions of Ce, La and Nd to Mg were made in binary, ternary and quaternary combinations up to {approx}6 wt.%. This provided a dataset that was used in developing a neural network model for predicting corrosion rate and yield strength. Whilst yield strength increased with RE additions, corrosion rates also systematically increased, however, this depended on the type of RE element added and the combination of elements added (along with differences in intermetallic morphology). This work is permits an understanding of Mg-RE alloy performance, and can be exploited in Mg alloy design for predictable combinations of strength and corrosion resistance.

  7. Thermodynamics and kinetics of the formation of rare earth intermetallics

    International Nuclear Information System (INIS)

    Deodhar, S.S.

    1975-01-01

    Heats of reaction of rare earth intermetallics with iron, cobalt and nickel were determined using Differential Thermal Analysis technique. The intermetallic compounds studied were of MgCu 2 type Laves phases and the rare earth elements studied were praseodymium, gadolinium, dyprosium and erbium. The reactions were exothermic and the heats of reaction were generally high. They varied from the low of -2.5 kcal/g mole for Fe 2 Gd to the high of -35.3 kcal/g mole for Ni 2 Er. The magnitudes of heats of reaction were always greater for the intermetallics of heavy rare earth elements. The rare earth intermetallics studied were either ferromagnetic or antiferromagnetic. The variations in the magnetic moments and the heats of reaction with respect to the atomic number of the rare earth elements followed certain trends. The similarities were observed in the trends of two properties. Electronic configuration for the MgCu 2 type rare earth intermetallics is proposed using Engel--Brewer correlation for metallic structures and the structural features of the Laves phase compounds. Kinetics of the reactions between the rare earth elements and iron, cobalt, and nickel was studied. The rate of reaction was diffusion controlled in each case. The Valensi--Carter equation for the diffusion mechanism satisfactorily described the kinetic behavior. The magnitudes of activation energies and frequency factors were determined. The reactions can be characterized by their reaction temperatures since they always begin at definite temperatures. It was observed that the reaction began at a higher temperature if the activation energy for the reaction was high

  8. Metallothermic reduction of rare earth oxides

    International Nuclear Information System (INIS)

    Sharma, R.A.

    1986-01-01

    Rare earth oxides can be reduced to rare earth metals by a novel, high yield, metallothermic process. The oxides are dispersed in a suitable, molten, calcium chloride bath along with sodium metal. The sodium reacts with the calcium chloride to produce calcium metal which reduces the rare earth oxides to rare earth metals. The metals are collected in a discrete layer in the reaction vessel

  9. Spectral determination of individual rare earths in different classes of inorganic compounds

    International Nuclear Information System (INIS)

    Karpenko, L.I.; Fadeeva, L.A.; Shevchenko, L.D.

    1979-01-01

    The conditions are found allowing to analyze various inorganic compounds for rare-earth elements without separation from non-rare-earth components. The influence of the plasma composition on the intensity of spectral lines of rare-earth elements is studied. The relative intensity of homologous spectral lines of various rare-earth elements remains constant regardless of the plasma composition. The conditions are found for the determination of individual rare-earth elements acting as both alloying additives (Csub(n) -- n x 10 -1 -n x 10 -3 %), and basic components (up to tens of per cent) in different classes of inorganic compounds of 1-7 elements. The general method is developed for the determination of individual rare-earth elements in mixtures of oxides of rare-earth elements, complex fluorides of rare-earth elements and elements of group 2, gallates, borates, germanates, vanadates of rare-earth elements and aluminium; zirconates-titanates of lead and barium, containing modifying additives of rare-earth elements, complex chalcogenides of rare-earth elements and elements of group 5

  10. Achieving excellent thermal stability and very high activation energy in an ultrafine-grained magnesium silver rare earth alloy prepared by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Khan MD, F. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Panigrahi, S.K., E-mail: skpanigrahi@iitm.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-10-15

    Ultrafine-grained microstructure of a QE22 alloy prepared by Friction Stir processing (FSP) is isochronally annealed to study the thermal stability and grain growth kinetics. The FSPed microstructure of QE22 alloy is thermally stable under ultrafine-grained regime up to 300 °C and the activation energy required for grain growth is found to be exceptionally high as compared to conventional ultrafine-grained magnesium alloys. The high thermal stability and activation energy of the FSPed QE22 alloy is due to Zener pinning effect from thermally stable eutectic Mg{sub 12}Nd and fine precipitates Mg{sub 12}Nd{sub 2}Ag and solute drag effect from segregation of Neodymium (Nd) solute atoms at grain boundaries.

  11. A combined neural network and mechanistic approach for the prediction of corrosion rate and yield strength of magnesium-rare earth alloys

    International Nuclear Information System (INIS)

    Birbilis, N.; Cavanaugh, M.K.; Sudholz, A.D.; Zhu, S.M.; Easton, M.A.; Gibson, M.A.

    2011-01-01

    Research highlights: → This study presents a body of corrosion data for a set of custom alloys and displays this in multivariable space. These alloys represent the next generation of Mg alloys for auto applications. → The data is processed using an ANN model, which makes it possible to yield a single expression for prediction of corrosion rate (and strength) as a function of any input composition (of Ce, La or Nd between 0 and 6 wt.%). → The relative influence of the various RE elements on corrosion is assessed, with the outcome that Nd additions can offer comparable strength with minimal rise in corrosion rate. → The morphology and solute present in the eutectic region itself (as opposed to just the intermetallic presence) was shown - for the first time - to also be a key contributor to corrosion. → The above approach sets the foundation for rational alloy design of alloys with corrosion performance in mind. - Abstract: Additions of Ce, La and Nd to Mg were made in binary, ternary and quaternary combinations up to ∼6 wt.%. This provided a dataset that was used in developing a neural network model for predicting corrosion rate and yield strength. Whilst yield strength increased with RE additions, corrosion rates also systematically increased, however, this depended on the type of RE element added and the combination of elements added (along with differences in intermetallic morphology). This work is permits an understanding of Mg-RE alloy performance, and can be exploited in Mg alloy design for predictable combinations of strength and corrosion resistance.

  12. Determination of lanthanum and rare earth elements in bovine whole blood reference material by ICP-MS after coprecipitation preconcentration with heme-iron as coprecipitant

    International Nuclear Information System (INIS)

    Fujimori, Eiji; Hayashi, Tatsuya; Inagaki, Kazumi; Haraguchi, H.

    1999-01-01

    An analytical method for the determination of lanthanide elements in the bovine whole blood reference material (IAEA A-13) has been investigated by inductively coupled plasma mass spectrometry (ICP-MS). The bovine whole blood reference material was digested with HNO 3 and HClO 4 , and then the pH of the digested solution was adjusted to 12 with 3 M sodium hydroxide aqueous solution. In this experimental procedure, lanthanide elements in the blood sample were coprecipitated with iron mainly derived from heme-iron in blood itself. In order to minimize matrix effects due to iron, excess iron in the analysis solution was removed by solvent extraction using methyl isobutyl ketone (MIBK) prior to the determination of lanthanide elements by ICP-MS. The recoveries of all lanthanide elements were almost quantitative in the recovery test. In consequence, it has been found that all lanthanide elements in bovine whole blood reference material are at the wide concentration range of 0.90 pg/g for Tm ∝1880 pg/g for Ce. (orig.)

  13. Magnetic interactions in equi-atomic rare-earth intermetallic alloys RScGe (R = Ce, Pr, Nd and Gd) studied by time differential perturbed angular correlation spectroscopy and ab initio calculations.

    Science.gov (United States)

    Mishra, S N

    2009-03-18

    Applying the time differential perturbed angular correlation (TDPAC) technique we have measured electric and magnetic hyperfine fields of the (111)Cd impurity in equi-atomic rare-earth intermetallic alloys RScGe (R = Ce, Pr and Gd) showing antiferro- and ferromagnetism with unusually high ordering temperatures. The Cd nuclei occupying the Sc site show high magnetic hyperfine fields with saturation values B(hf)(0) = 21 kG, 45 kG and 189 kG in CeScGe, PrScGe and GdScGe, respectively. By comparing the results with the hyperfine field data of Cd in rare-earth metals and estimations from the RKKY model, we find evidence for the presence of additional spin density at the probe nucleus, possibly due to spin polarization of Sc d band electrons. The principal electric field gradient component V(zz) in CeScGe, PrScGe and GdScGe has been determined to be 5.3 × 10(21) V m(-2), 5.5 × 10(21) V m(-2) and 5.6 × 10(21) V m(-2), respectively. Supplementing the experimental measurements, we have carried out ab initio calculations for pure and Cd-doped RScGe compounds with R = Ce, Pr, Nd and Gd using the full potential linearized augmented plane wave (FLAPW) method based on density functional theory (DFT). From the total energies calculated with and without spin polarization we find ferrimagnetic ground states for CeScGe and PrScGe while NdScGe and GdScGe are ferromagnetic. In addition, we find a sizable magnetic moment at the Sc site, increasing from ≈0.10 μ(B) in CeScGe to ≈0.3 μ(B) in GdScGe, confirming the spin polarization of Sc d band electrons. The calculated electric field gradient and magnetic hyperfine fields of the Cd impurity closely agree with the experimental values. We believe spin polarization of Sc 3d band electrons, strongly hybridized with spin polarized 5d band electrons of the rare-earth, enables a long range Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between RE 4f moments which in turn leads to high magnetic ordering temperatures in

  14. The role of rare earths in narrow energy gap semiconductors

    International Nuclear Information System (INIS)

    Partin, D.L.; Heremans, J.; Morelli, D.T.; Thrush, C.M.

    1991-01-01

    Narrow energy band gap semiconductors are potentially useful for various devices, including infrared detectors and diode lasers. Rare earth elements have been introduced into lead chalcogenide semiconductors using the molecular beam epitaxy growth process. Europium and ytterbium increase the energy band gap, and nearly lattice-matched heterojunctions have been grown. In some cases, valence changes in the rare earth element cause doping of the alloy. In this paper some initial investigations of the addition of europium to indium antimonide are reported, including the variation of lattice parameter and optical transmission with composition and a negative magnetoresistance effect

  15. The Chinese Society of Rare Earth is Studying The Feasibility of Marketing Rare Earth Futures

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Lin Donglu,secretary-general of the Chinese Society of Rare Earth recently said,the Chinese Society of Rare Earth undertook the research on subject of the National Social Science Fund Foundation on the reform of Chinese rare earth trading pricing mechanism on promoting RMB globalization,and is focusing on studying the feasibility of marketing rare earth futures variety.

  16. Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jonghyun, E-mail: joindoc@kumamoto-u.ac.jp [Department of Material Science, Magnesium Research Center (MRC), Kumamoto University, Kumamoto, 860-8555 (Japan); Kawamura, Y. [Department of Material Science, Magnesium Research Center (MRC), Kumamoto University, Kumamoto, 860-8555 (Japan)

    2013-06-20

    Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} (RE=La, Ce, Nd and Sm, at. %) alloys were prepared by high-frequency induction melting in an Ar atmosphere. Rods were extruded at 623 K and a ram speed of 2.5 mm·s{sup −1} using a circular die with an extrusion ratio of 10. The microstructure and mechanical properties of the extruded alloys were investigated. The Mg{sub 97}Zn{sub 1}Y{sub 1}Nd{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Sm{sub 1} alloys consisted of only two phases: α-Mg and a Mg-RE intermetallic compound. The Mg{sub 97}Zn{sub 1}Y{sub 1}La{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Ce{sub 1} alloys consisted of three phases: α-Mg, a Mg-RE intermetallic compound, and a Mg{sub 12}ZnY phase with a long-period stacking ordered (LPSO) phase. Additionally, after extrusion, the three-phase Mg{sub 97}Zn{sub 1}Y{sub 1}RE{sub 1} alloys, i.e., those with an LPSO phase, had a stratified microstructure and exhibited better mechanical properties than those without an LPSO. At room temperature, the yield strength and ultimate tensile strength of the three-phase Mg{sub 97}Zn{sub 1}Y{sub 1}La{sub 1} and Mg{sub 97}Zn{sub 1}Y{sub 1}Ce{sub 1} alloys were 381–384 MPa and 427–429 MPa, respectively, and yield strengths greater than 280 MPa were observed at the elevated temperature of 523 K.

  17. Process for making rare earth metal chlorides

    International Nuclear Information System (INIS)

    Kruesi, P.R.

    1981-01-01

    An uncombined metal or a metal compound such as a sulfide, oxide, carbonate or sulfate is converted in a liquid salt bath to the corresponding metal chloride by reacting it with chlorine gas or a chlorine donor. The process applies to metals of groups 1b, 2a, 2b, 3a, 3b, 4a, 5a and 8 of the periodic table and to the rare earth metals. The chlorine donor may be ferric or sulfur chloride. The liquid fused salt bath is made up of chlorides of alkali metals, alkaline earth metals, ammonia, zinc and ferric iron. Because the formed metal chlorides are soluble in the liquid fused salt bath, they can be recovered by various conventional means

  18. Geological research on rare earth elements, results and outlook

    International Nuclear Information System (INIS)

    Fortin, H

    1999-01-01

    This is a report of the geological investigation of rare earth elements carried out by CCHEN and ENAMI (Empresa Nacional de Mineria) over 70,000 square kilometers in Chile's northern coastal mountain range. Twenty areas were identified with sphena, davidite, ilmenite, pyroxene, anatase and magnetite minerals containing 0.3 kg/t to 6.0 kg/t of rare earth elements. Additional research on Cerro Carmen Prospect, located near Diego de Almagro, define it as a metasomatic deposit, hosted in metamorphic contact rocks, between andesites (Pliensbachian to early Jurassic) and intrusive monzonitic rocks. This information increases knowledge about the metallogenesis of Chile's copper - iron - rare earth - uranium deposits and the application of this geological model of ore deposits as defined in Australia's Olympic Dam

  19. On the microstructural factors affecting creep resistance of die-cast Mg–La-rare earth (Nd, Y or Gd) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gavras, S. [Magnesium Innovation Centre, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, Geesthacht (Germany); Zhu, S.M. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia); Nie, J.F. [Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); Gibson, M.A. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia); Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); CSIRO Manufacturing, Clayton, Victoria 3168 (Australia); Easton, M.A. [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Carlton, Victoria 3053 (Australia)

    2016-10-15

    Creep properties of high-pressure die-cast Mg–La-RE (Nd, Y or Gd) alloys, varying in ternary RE additions and in different heat treatment conditions, have been investigated. Through the use of short-term solution treatments (1 h at 520 °C) it was shown that the continuous intermetallic phase present in the eutectic at grain boundaries became discontinuous. This effect, in combination with the likely removal of the localised region of supersaturated solute in solid solution near grain boundaries, reduced the creep resistance. When relatively high concentrations of ternary alloying additions were used, solid solution strengthening and precipitation hardening appeared to compensate for the negative effect of reduced grain boundary reinforcement. Microstructural investigation revealed that Nd-containing alloys had fewer and larger dynamic precipitates present in the α-Mg matrix following creep testing at 177 °C and 90 MPa. It was concluded that grain boundary reinforcement in combination with the thermal stability of the precipitates formed, which is ultimately related to the diffusivity of solute in solid solution, are also contributing factors to creep resistance.

  20. Progress in development of iron base alloys

    International Nuclear Information System (INIS)

    Zackay, V.V.; Parker, E.R.

    1980-01-01

    The ways of development of new iron base high-strength alloys are considered. Perspectiveness of ferritic steel strengthening with intermetallides (TaFe 2 , for instance) is shown. Favourable combination of plasticity, strength and fracture toughness in nickel-free iron-manganese alloys (16-20%) is also pointed out. A strength level of alloyed maraging steels can be achieved by changes in chemical composition and by proper heat treatments of low- and medium-alloyed steels

  1. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

    Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

    2009-01-01

    Raman scattering spectra were measured for the rare-earth hexaborides RB 6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B 6 vibrations were observed in the range 600 - 1400 cm -1 . Anomalous peaks were detected below 200 cm -1 , which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

  2. Rare earth metals for automotive exhaust catalysts

    International Nuclear Information System (INIS)

    Shinjoh, Hirohumi

    2006-01-01

    The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

  3. Rare earth industries: Strategies for Malaysia

    International Nuclear Information System (INIS)

    2011-01-01

    Evidently, many reports cite Malaysia as having reasonably substantial amounts of rare earths elements. In fact, based on the rare earths found in the residual tin deposits alone, Malaysia has about 30,000 tonnes. This does not take into account unmapped deposits which experts believe may offer more tonnages of rare earths. Brazil which is reported to have about 48,000 tonnes has announced plans to invest aggressively in the rare earths business. China has on record the largest reserves with about 36 million tonnes. This explains why China has invested heavily in the entire value chain of the rare earths business. Chinas committed investment in rare earths started many years ago when the country's foremost leaders proclaimed the strategic position of rare earths in the world economy. That forecast is now a reality where the rise in the green high-tech economy is seen driving global demand for rare earths in a big way. Malaysia needs to discover and venture into new economic growth areas. This will help fuel the country's drive to achieve a high income status by 2020 as articulated in the New Economic Model (NEM) and the many supporting Economic Transformation Plans that the Government has recently launched. Rare earths may be the new growth area for Malaysia. However, the business opportunities should not just be confined to the mining, extraction and production of rare earths elements alone if Malaysia is to maximise benefits from this industry. The industry's gold mine is in the downstream products. This is also the sector that China wants to expand. Japan which now controls about 50 % of the global market for downstream rare earths-based high-tech components is desperately looking for partners to grow their stake in the business. Malaysia needs to embark on the right strategies in order to build the rare earths industry in the country. What are the strategies? (author)

  4. Rare earth - no case for government intervention

    OpenAIRE

    Georg Zachmann

    2010-01-01

    China has officially restricted exports of rare earth for several years and announced this year it will further tighten exports. Rare earth is a group of 17 different metals, usually found clustered together. These metals have hundreds of different industry applications. For example, they are used in certain high capacity magnets, batteries and lasers. As the rare earth elements are used in sectors that are assumed to have an over-proportionate growth potential (eg. green-technology), policy ...

  5. Alaska's rare earth deposits and resource potential

    Science.gov (United States)

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

    2012-01-01

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

  6. Rare Earth Metal-Based Intermetallics Formation in Al–Cu–Mg and Al–Si–Cu–Mg Alloys: A Metallographic Study

    Directory of Open Access Journals (Sweden)

    A. M. Samuel

    2018-01-01

    Full Text Available This study was conducted on Al–Cu–Mg and Al–Si–Cu–Mg alloys containing either 5%La or 5%Ce. Two levels of Ti addition were examined, i.e., 0.05% and 0.15%. Thermal analysis was the only technique used to obtain castings, from which samples were then sectioned for metallographic examination. Based on the results obtained, the following points may be highlighted. Addition of a fairly large amount of RE metals (La or Ce leads to the appearance of several peaks in the solidification curve between the precipitation of the primary α-Al phase and the (Al–Al2Cu eutectic reaction. Although a significant drop in the eutectic temperature is caused by the addition of 5%La or Ce, the corresponding modification of the eutectic Si is marginal. Two main types of intermetallics were documented: a gray phase in the form of sludge with a fixed composition and a white phase in the shape of thin platelets. Due to the high affinity of RE to react with Si, Fe, and Cu, several compositions were obtained explaining the observed multiple peaks in the solidification curve. Judging by the morphology of the gray phase, it is assumed that this phase is precipitated in the liquid state and acts as a nucleation site for the white phase. Lanthanum and Ce can substitute each other.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-08-21

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

  8. Recycling of Rare Earth Elements

    Science.gov (United States)

    Lorenz, Tom; Bertau, Martin

    2017-01-01

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

  9. Recycling of rare earth magnet scraps: Carbon and oxygen removal from Nd magnet scraps

    International Nuclear Information System (INIS)

    Saguchi, A.; Asabe, K.; Fukuda, T.; Takahashi, W.; Suzuki, R.O.

    2006-01-01

    The decarburization and deoxidation technique for permanent Nd-Fe-B magnet scrap is investigated. The carbon and oxygen contamination damage the magnetic properties. The carbon content decreased less than 0.001% by heating in air. The two stage deoxidation is applied, iron oxides are reduced by heating in hydrogen thereafter rare earth oxides are removed by Ca-reduction and leaching. The appropriate conditions for deoxidation in the Ca-reduction and suppressing the re-oxidation in the leaching are investigated. The heating pattern in Ca-reduction and the leaching condition for the mixture composed of Ca compounds and Nd-Fe-B alloy powder greatly affects the oxygen content of recycled material. The decarburized and deoxidized Nd-Fe-B magnet scrap can be recycled as alloying elements by melting

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

    Science.gov (United States)

    Hedrick, James B.

    1997-01-01

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

  11. Rare earth oxyhydrides and preparation process

    International Nuclear Information System (INIS)

    Diaz, H.

    1986-01-01

    Rare earth oxyhydrides of formula RE 1-q Th q Ni 5-p M p O x H y are claimed. RE is a rare earth, Th can be replaced by Yt, M is Cu, Mn, Al, Fe, Cr or Co, o O C and the hydrides are oxidized. They are catalysts for various chemical reactions [fr

  12. Process for lead removal from rare earth

    International Nuclear Information System (INIS)

    Bollat, A.; Sabot, J.L.

    1987-01-01

    An aqueous solution of rare earth chlorides and lead chlorides, with a chloride concentration of at least 2 moles/liter and a pH between 2 and 4, is extracted by an alkylphosphonic acid ester and rare earth(s) is (are) recovered from the organic phase [fr

  13. Rare Earth Elements Distribution in Beryl

    International Nuclear Information System (INIS)

    El Gawish, H.K.; Nada, N.; Ghaly, W.A.; Helal, A.I.

    2012-01-01

    Laser ablation method is applied to a double focusing inductively coupled plasma mass spectrometer to determine the rare earth element distribution in some selected beryl samples. White, green and blue beryl samples are selected from the Egyptian eastern desert. Distributions of chondrite- normalized plot for the rare earth element in the selected beryl samples are investigated

  14. Rare Earth Metals: Resourcefulness and Recovery

    Science.gov (United States)

    Wang, Shijie

    2013-10-01

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

  15. Development of rare earth regenerator materials in fine wire form

    International Nuclear Information System (INIS)

    Wong, T.; Seuntjens, J.M.

    1997-01-01

    The use of rare earth metals, both in the pure and alloyed state, have been examined for use as regenerators in cryocooler applications and as the working material in active magnetic refrigerators. In both applications there is a requirement for the rare earth material to have a constant and uniform cross section, an average size on the order of 50-200 microns in diameter, and low levels of impurities. Existing powder production methods have drawbacks such as oxygen contamination, non-uniform size, inconsistent cross sections, and low production yields. A novel approach for the production of rare earth metals and alloys in fine wire form has been developed. This is accomplished by assembling a copperjacket and niobium barrier around a RE ingot, extruding the assembly, and reducing it with standard wire drawing practices. Strand anneals are utilized between drawing passes when necessary in order to recrystallize the RE core and restore ductility. The copperjacket is removed by chemical means at final size, leaving the Nb barrier in place as a protective coating. This process has been applied to gadolinium, dysprosium and a GdDy alloy

  16. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  17. Thermochemistry of rare-earth trifluorides

    International Nuclear Information System (INIS)

    Kim, K.Y.; Johnson, C.E.

    1981-01-01

    Using the most recent crystallographic data, the Born-Lande equation was employed to calculate lattice energies of the rare-earth trifluorides. The excellent agreement ( 0 sub(f)(MX 3 ,c,298.15K) can be estimated. The magnitude of the monotonic change of ΔH 0 sub(f)(MX 3 ) for the rare-earth trihalides series (14 4f electrons) is comparable to the energy change between Sc and Ti in which only one 3d electron is added. This energy change is consistent with the chemical evidence that the electrons in the f-orbitals of rare earths contribute negligibly to the bonding. (author)

  18. State of rare earth impurities in gallium and indium antimonides

    International Nuclear Information System (INIS)

    Evgen'ev, S.B.; Kuz'micheva, G.M.

    1990-01-01

    State of rare earth impurities in indium and gallium antimonides was studied. Results of measuring density and lattice parameter of samples in GaSb-rare earth and InSb-rare earth systems are presented. It is shown that during rare earth dissolution in indium and gallium antimonides rare earth atoms occupy interstitial positions or, at least, are displaced from lattice points

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

    Science.gov (United States)

    Jackson, W.D.; Christiansen, Grey

    1993-01-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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 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

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

    Science.gov (United States)

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

    2015-05-01

    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 NdCo5. 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.

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

    Science.gov (United States)

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

    2016-11-01

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

  3. Thermodynamics of rare earths in steelmaking

    International Nuclear Information System (INIS)

    Vahed, A.; Kay, D.A.R.

    1976-01-01

    The standard free energies of formation of the oxides, sulfides and oxysulfides of cerium and lanthanum under steelmaking conditions have been calculated and used to predict the behavior of rare earths in steelmaking. Deoxidation and desulfurization constants, expressed in terms of Henrian activities, have been used to construct a precipitation diagram which indicates the sequence of rare earth inclusion formation. An enrichment of lanthanum in (RE)-oxysulfide and cerium in (RE)-sulfide is predicted. It is also predicted that rare earths should be able to reduce the soluble oxygen and sulfur contents of liquid steel well below the contents presently found in most industrial and laboratory practices. A simple method of calculating steelmaking additions for complete rare earth control of inclusion composition is presented

  4. Structural and electronic properties of binary amorphous aluminum alloys with transition metals and rare earth metals; Strukturelle und elektronische Eigenschaften binaerer amorpher Aluminiumlegierungen mit Uebergangsmetallen und Metallen der Seltenen Erden

    Energy Technology Data Exchange (ETDEWEB)

    Stiehler, Martin

    2012-02-03

    The influence of the d-states of the transition metals on the structure formation in amorphous alloys has so far only been inadequately understood. The present work aims to elaborate additional contributions to the understanding of binary amorphous aluminum alloys with transition metals. Special emphasis was placed on alloys with a subgroup of the transition metals, the rare earth metals. Within the scope of the present work, layers of Al-Ce in the region of 15at% Ce-80at% Ce were produced by sequential flash evaporation at 4.2K in the high vacuum, and characterized electronically by electrical resistance and Hall effect measurements as well as structurally by transmission electron diffraction. In addition, studies of plasma resonance were carried out by means of electron energy loss spectroscopy. In the range of 25at% Ce-60at% Ce, homogeneous amorphous samples were obtained. Especially the structural investigations were made difficult by oxidation of the material. The influence of the Ce-4f electrons manifests itself mainly in the low-temperature and magnetoresistance, both of which are dominated by the Kondo effect. The Hall effect in Al-Ce is dominated by anomalous components over the entire temperature range (2K-320K), which are attributed to skew-scattering effects, also due to Ce-4f electrons. Down to 2K there was no macroscopic magnetic order. In the region 2K-20K, the existence of clusters of ordered magnetic moments is concluded. For T> 20K, paramagnetic behavior occurs. With regard to the structural and electronic properties, a-Al-Ce can be classified as a group with a-Al- (Sc, Y, La). In the sense of plasma resonance, a-Al-Ce is excellently arranged in a system known from other Al transition metal alloys. Furthermore, by increasing the results of binary amorphous Al transition metal alloys from the literature, it has been found that the structure formation in these systems is closely linked to a known but still unexplained structure-forming effect that

  5. 12 Ministries Control Rare Earth Exports

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>"It is very natural to reserve rare earth as a strategic resource.Many countries do this,including China."On April 8,Sun Lihui,Vice Director of Metal Section of Chemicals Import & Export Commerce Chamber of China Minmetals Corporation told a reporter that as early as 2006,China has launched a strategic plan for rare earth,"but it was interrupted by the subsequent financial crisis."

  6. 2004 Top 10 Chinese Rare Earth Events

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1. Management to the Investment in Rare Earth IndustryConfirmedIn July 2004, "Decision on the Reform in Investment System" was formally publicized by the State Council of the People's Republic of China. The fifth item in the Decision stipulates that ore exploitation, smelting & separation and rare earth deep-processed projects with total investment over RMB¥100 million should be approved by the investment governing department of the State Council, and that other

  7. Mammography with rare earth intensifying screens

    International Nuclear Information System (INIS)

    Maurer, H.J.; Goos, F.

    1987-01-01

    Screens basing on rare earth phosphors with suitable films green or blue sensitive may be used in mammography with grids without diagnostic losses. Highest definition will be obtained with medium densities on film. High-speed screens may reduce dose, but definition is poor. Best compromise between speed and high definition may be reached with relative low thickness of phosphor layers. A system of high definition films (Medichrome) and special rare earth screens give best results. (orig.) [de

  8. Rare earths refining by vacuum sublimation method

    International Nuclear Information System (INIS)

    Rytus, N.N.

    1983-01-01

    The process of rare earths refining by the sUblimation; method in high and superhigh oil-free vacuum, is investigated. The method is effective for rare earths obtaining and permits to prepare metal samples with a high value of electric resistance ratio γ=RsUb(298 K)/Rsub(4.2 K). The estimation of general purity is performed for Sm, Eu, Yb, Tm, Dy, Ho, Er and Se

  9. Rare earth mobility in hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

    Cornell, D.H.; Schade, J.; Scheepers, R.; Watkeys, M.K.

    1988-01-01

    Rocks and ores which form by magmatic processes display a range of chondrite-normalised rare earth profiles. One REE (rare earth elements) profile feature which seems unrelated to magmatic processes is the birdwing profile, in which both heavy and light rare earths are enriched relative to the middle rare earths. Birdwing rare earth profiles are an easily identified geochemical anomaly. It is proposed that rare earth geochemistry could be applied in geochemical prospecting for ore formed by hydrothermal processes. 5 figs

  10. On the effects of magnetic bonding in rare earth transition metal intermetallics

    International Nuclear Information System (INIS)

    Kumar, R.; Bentley, J.; Yelon, W.B.

    1990-01-01

    Neutron diffraction experiments on rare-earth transition metal magnetic alloys Er 2 Fe 14 B and Er 2 Fe 17 have been carried out at temperature above and below the ordering temperature (T c ). An anomalously large magnetic moment is observed at the crystallographic j 2 site in Er 2 Fe 14 B which is the intersection point of the major ligand lines in the crystal structure. The interatomic Fe-Fe distances are in the range of strong ferromagnetic bonds (≥ 2.66 angstrom). The analogous f site in Er 2 Fe 17 does not develop as large a magnetic moment. In addition, the same sites show strong preference for Fe atoms in the respective substituted compounds. Due to poor phase stability of Er 2 (Co x Fe 1 -x ) 14 B compounds, iron substitution has been studied in detail in Er 2 (Co x Fe 1 -x ) 17 alloys for site specific order an lattice distortion effects. However, a nonlinear change in the c lattice parameter observed in the neutron diffraction results cannot be explained on the basis of site preference alone. The neutron refinement results indicate iron rich compositions in Er 2 (Co x Fe 1 -x ) 17 materials, which is related to random substitution of Fe dumbbell pairs in the rare earth sites in the lattice. However, extensive electron microscopy (selected area electron diffraction and high resolution imaging) of Er 2 Fe 17 and Er 2 (Co .40 Fe .60 ) 17 failed to reveal any microscopic inhomogeneity. 12 refs., 5 figs., 2 tabs

  11. Rare earths production and marketing opportunities

    International Nuclear Information System (INIS)

    Falconnet, P.G.

    1988-01-01

    The rare earths (RE) market is relatively small. The total production during 1968 was only 10000 tons (REO) which rose to 27000 tons (REO) during 1985. The three major areas of application, which are volume market for ceric rare earths are catalysts, glass ceramics and metallurgy. Among the other uses of rare earths, the permanent magnets, lamp phosphors and fine ceramics have registered significant growth in RE consumption. Monazite and bastnasite are the main natural source for rare earths and processing of these for one of the rare earths in high demand leads to over production of some others not in demand, thus creating a balance problem. The growth in RE market has always been influenced by the technology shifts and product substitution. For example, the RE consumption during 1974/76 for desulfurization of steel had substantially decreased due to the usage of calcium. Similarly, 1985 had witnessed a drastic cut in the use of REs in fluid cracking due to the introduction of stabilized zeolites which contain less REO. Thus, the overall compound growth rate of demand was only 3.9 % per year during the period 1970-1985. At present, 37 % of the rare earths production goes to the glass/ceramics industry, 33 % for catalyst and 25 % to metallurgy. The price of REs constantly shows a downward trend. This trend coupled with the rapid changes taking place in the various technological fields, demands greater flexibility and high marketing skills from the RE producers. The key factor for future expansion of RE market will be the development of 'high volume' application of ceric rare earths. (author) 2 figs., 8 tabs

  12. Rare earth elements and permanent magnets (invited)

    Science.gov (United States)

    Dent, Peter C.

    2012-04-01

    Rare earth (RE) magnets have become virtually indispensible in a wide variety of industries such as aerospace, automotive, electronics, medical, and military. RE elements are essential ingredients in these high performance magnets based on intermetallic compounds RECo5, RE2TM17 (TM: transition metal), and RE2TM14B. Rare earth magnets are known for their superior magnetic properties—high induction, and coercive force. These properties arise due to the extremely high magnetocrystalline anisotropy made possible by unique 3d-4f interactions between transition metals and rare earths. For more than 40 years, these magnets remain the number one choice in applications that require high magnetic fields in extreme operating conditions—high demagnetization forces and high temperature. EEC produces and specializes in RECo5 and RE2TM17 type sintered magnets. Samarium and gadolinium are key RE ingredients in the powder metallurgical magnet production processes which include melting, crushing, jet milling, pressing, sintering, and heat treating. The magnetic properties and applications of these magnets will be discussed. We will also briefly discuss the past, current, and future of the permanent magnet business. Currently, over 95% of all pure rare earth oxides are sourced from China, which currently controls the market. We will provide insights regarding current and potential new magnet technologies and designer choices, which may mitigate rare earth supply chain issues now and into the future.

  13. Concentration of rare earths ore from Pocos de Caldas - MG, Brazil

    International Nuclear Information System (INIS)

    Sampaio, J.A.; Lins, F.F.; Porphirio, N.H.

    1990-01-01

    The objective of this research was to concentrate, mainly by flotation, a rare-earth ore body. The valuable mineral is bastnaesite which occurs intimately associated with iron oxides and other gangue minerals, making difficult to get a concentrate of commercial grade. The use of oleic acid at a pulp temperature of -80 sup(0)C gave a concentrate of 23% rare-earth oxides at 72% overall recovery. The magnetic separation could enhance the grade of the flotation feed. (author)

  14. Recovery of rare earth minerals, with emphasis on flotation process

    International Nuclear Information System (INIS)

    Houot, R.; Cuif, J.P.; Mottot, Y.; Samama, J.C.

    1991-01-01

    Bastnasite and monazite are the two major minerals used commercially to supply most of the rare earths. Monazite is often a by-product of the concentration of heavy minerals of zirconium and titanium in beach sands. Thus, the methods of concentration are gravity (spirals, Reichert cones and shaking tables), ending with magnetism, electrostatic and in certain cases, flotation. The two main deposits of bastnasite are Mountain Pass (U.S.A.) and Bayan Obo (China). The rock bastnasite content is within 15% and the recovery of rare earth minerals is made through flotation. The flowsheets are complex enough because the existence of accompanying minerals such as quartz, iron components, barite, fluorite, calcite, etc. The conditioning is done by heating and the frequently employed collector is a fatty acid associated with selective agents, as sodium silicate or fluosilicate, lignin sulphonate, sodium carbonate, aluminium salts, etc. Recent studies tempt to introduce the use of phosphoric esters, dicarboxilic, sulphonic and/or sulphosuccinic acids. Concentrates with 60% REO are then treated with acidic solution to eliminate residual calcite. The possibility of obtaining products enriched with rare earths are also noted: these are ores of uranium (Elliot Lake), pyrochlore, apatite, and other complex ores with euxenite, fergusonite or loparite. (author) 10 figs., 6 tabs., 57 refs

  15. Coprecipitation of rare earth elements with hydroxyapatite

    International Nuclear Information System (INIS)

    Fujino, Osamu

    1979-01-01

    The distribution behavior of trace rare earth elements between an aqueous phase and hydroxyapatite crystals was investigated. The apatite prepared by adding phosphate ion extremely slowly to an aqueous solution containing calcium, rare earth elements, ethylenediamine and nitrilotriacetate ion at 80 0 C. Apparently the coprecipitation reaction seems to be anomalous, because the apparent distribution coefficient did not have a constant value through the reaction. But when the true distribution coefficient was calculated by using the thermodynamic data at 80 0 C, it was revealed that rare earth ions were coprecipitated obeying logarithmic distribution law. The true distribution coefficient values of trivalent yttrium, scandium, europium and cerium ions were about 10sup(7.3), 10sup(9.8), 10sup(7.4) and 10sup(6.5) respectively. (author)

  16. Rare earths: harvesting basic research for technology

    International Nuclear Information System (INIS)

    Jagatap, B.N.

    2014-01-01

    In recent years, rare earths are increasingly becoming a versatile platform for basic research that presents enormous technological potentials. A variety of nano-sized inorganic matrices varying from oxides, phosphates, gallates and aluminates, tungstates, stannates, vanadates to fluorides doped with different lanthanide ions have been synthesized and their optical properties have been investigated in the Chemistry Group, BARC. Another interesting application is laser cooling of solids using rare earth doped glasses with potential applications in remote cooling of electronic devices. Combining the luminescence properties of rare earths with photonic crystals is yet another potent area with wide ranging applications. In this presentation we provide an overview of these developments with examples from the R and D programs of the Chemistry Group, BARC

  17. On fluorozirconates and fluorohafnates of rare earths

    International Nuclear Information System (INIS)

    Korenev, Yu.M.; Antipov, P.I.; Novoselova, A.V.

    1980-01-01

    It has been shown by the method of X-ray phase analysis that on interaction between rare-earth fluorides and zirconium and hafnium tetrafluorides, compounds with 1:1, 1:2, 1:3 molar ratios of components are formed. Compounds of the LnHfF 4 type are prepared for all rare-earths. Fluoro-metals of the LnHf 2 F 11 composition are typical only of light lanthanides from lanthanum to neodymium, while pentafluorated salts Ln(EF 5 ) 3 are formed in the reaction between EF 4 with fluorides of heavy rare-earth elements from samarium to lutecium, as well as with yttrium trifluoride. Parameters of unit cells of heptafluohafnates and pentafluometallates are determined

  18. X-ray dichroism of rare earth materials

    International Nuclear Information System (INIS)

    Goedkoop, J.B.

    1989-01-01

    The theme of this thesis is the investigation of the strong polarization dependende, or dichroism, that occur in the X-ray absorption spectra of rare earth materials. The rare earth elements distinguish themselves from the other elements through the behaviour of the 4f electrons which form the valence shell. This shell lies deep inside the atom, with the result that influences from the surrounding solid are well screened off by the outer electrons, so that even in the solid the 4f shell behaves very much like a in free atom or ion, and is almost completely spherically symmetric. Perturbations from the solid environment however always disturb this symmetry to some extend, with the result that the absorption spectrum becomes dependent on the mutual orientation of the polarization vector of the radiation and the ion. Earlier the existence of a strong magnetic X-ray dichroism (MXD) in the 3d→4f transitions of rare earths. In this thesis this work is extended, to a small degree theoretically but mainly experimentally. MXD is used in experiments on bulk sample, terbium iron garnet, and on rare earth overlayers on a ferromagnetic surface, Ni(110). The results of the latter study show unequivocally the potential of the MXD technique. The second theme of the thesis concerns experimental developments in soft X-ray spectroscopy. A description is given of a double crystal monochromator beamline that was constructed by our group at LURE, France. Results of the use of an organic crystal - multilayer comination in such a monochromator is described. Also a method is described for the characterization of the resolution of soft X-ray monochromators. Finally a contribution to the characterization of the electron yield technique in the soft X-ray range is given. (author). 296 refs.; 64 figs.; 59 schemes; 9 tabs

  19. Features of rare earth element (3) complexing

    International Nuclear Information System (INIS)

    Martynenko, L.I.

    1991-01-01

    Reasons for nonobeyance to the regularity of tetrad ''W'' effect of rare earth chelate complex compounds are discussed in the review. The concept of metal-ligand ionic bond in rare earth complexes is put in the basis of the consideration. From this viewpoint mutual influence of ligands in lower, higher, polynuclear and different-ligand complexes, formed by the ligands of low, medium and high denticity, is discussed. Problems of intermolecular interaction of complexes with different structure are considered in relation to problems of variation of chelate volatility and selectivity in the processes of sublimation and precipitation

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

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood....... In the spiral phase of Ho, the structure in the c-axis distribution is much reduced, indicating that the Fermi surface is substantially modified by the magnetic ordering, as expected. The photon distribution from the equiatomic Ho-Er alloy is very similar to those from the constituent metals, although...

  1. Rare-earth magnets and their applications. Vol. 2. Proceedings

    International Nuclear Information System (INIS)

    Schultz, L.; Mueller, K.H.

    1998-01-01

    The following topics were dealt with: permanent magnets, rare- earth magnets, manufacturing, markets, powder metallurgy, sintering, mechanical alloying, nanocrystalline magnets, Curie temperature, domain structure, exchange coupling, stoichiometry effects, coercive force, remanence, magnetisation distribution, demagnetisation, mechanical properties, deformation behaviour, microstructure, grain size effects, texture, magnetic anisotropy, hydrogen assisted processing, nitriding, hydrogen embrittlement, permanent magnet motors, permanent magnet generators, brushless machines, linear motors, DC motors, AC motors, servomotors, magnetic levitation, magnetic field calculations, magnetic damping, magnet system design, system optimisation, corrosion protection, magnetometers, hard magnetic films, magnetostriction, magnetic multilayers, spin glass behaviour

  2. Magnetic anisotropy and neutron scattering studies of some rare earth metals

    International Nuclear Information System (INIS)

    Day, R.

    1978-08-01

    The thesis is concerned with magnetic anisotropy of dysprosium and alloys of gadolinium: yttrium, and also neutron scattering studies of dysprosium. The experiments are discussed under the topic headings: magnetic anisotropy, rare earths, torque measurements, elastic neutron scattering, inelastic neutron scattering, dysprosium measurements, and results for the gadolinium: yttrium alloys. (U.K.)

  3. The Marine Geochemistry of the Rare Earth Elements

    Science.gov (United States)

    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...seawater and algal food . When the radioactive particles were no longer available, the accumulated radioactivity of the zooplankters was rapidly lost

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

    Indian Academy of Sciences (India)

    Unknown

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

  5. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    2015-11-27

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Ultrasonic attenuation in rare-earth monoarsenides .... Proceedings of the International Workshop/Conference on Computational Condensed Matter Physics and Materials Science (IWCCMP-2015). Posted on November 27, 2015. Guest Editors: Anurag ...

  6. Rare earth oxyhalogenide base thermoluminescent material

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1976-01-01

    A process is described that consists to expose a thermoluminescent material to ionizing radiations, the material being a rare earth oxyhalogenide with terbium additions, to heat this material up to the emission of visible radiations and to measure the emitted radiations which are proportional to the ionizing radiation dose [fr

  7. Cerium and rare earth separation process

    International Nuclear Information System (INIS)

    Martin, M.; Rollat, M.

    1986-01-01

    An aqueous solution containing cerium III and rare earths is oxidized in the anodic compartment of an electrolytic cell, cerium IV is extracted by an organic solvent, the organic phase containing Ce IV is reduced in the catodic compartment of the same electrolytic cell and cerium III is extracted in a nitric aqueous phase [fr

  8. Lifetime measurements of the rare earths

    International Nuclear Information System (INIS)

    Stahnke, H.J.

    1981-01-01

    The lifetime of excited energy levels of Praseodymium, Neodymium, Gadolinium, Holmium and Erbium are measured. The measurements were done on atomic beams excited by laser radiation. The experimental results allow an interpretation of the electronic structure of the rare earths. (BEF)

  9. Anomalies in photofission of rare earth nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gann, A.V.; Nazarova, T.S.; Noga, V.I.; Ranyuk, Y.N.; Sorokin, P.V.; Telegin, Y.N.

    1979-09-01

    Measurements of photofission produced by 1-GeV bremsstrahlung in the heavy rare earth elements show an anomalously large cross section compared to that predicted by the liquid drop model. These measurements check the results obtained previously with 1-GeV protons by Andronenko et al. (JETP Lett. 24, 573 (1976)).

  10. Rare earth phosphors and phosphor screens

    International Nuclear Information System (INIS)

    Buchanan, R.A.; Maple, T.G.; Sklensky, A.F.

    1981-01-01

    Advances in the use of stabilized rare earth phosphors and of conversion screens using these materials are examined. In particular the new phosphors discussed in this invention consist of oxybromides of yttrium, lanthanum and gadolinium with a luminescent activator ion stabilized by an oxychloride or oxyfluoride surface layer and the conversion screens include trivalent cerium as the activator ion. (U.K.)

  11. Production technique of vermicular graphite iron cylinder head of vehicle diesel engine

    OpenAIRE

    Zhou Gen; Liu Wanhua

    2008-01-01

    The 25 years’production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermicularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfi ed vermicularity. ...

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

    DEFF Research Database (Denmark)

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

    1996-01-01

    The molecular beam epitaxy growth techniques which have already successfully produced a range of heavy rare-earth superlattices have now been extended to produce superlattices of two light rare-earth elements, Nd/Pr, as well as superlattices and alloy films of a heavy/light system, Ho/Pr. High......-resolution X-ray diffraction analysis shows the Nd/Pr superlattices to be of high structural quality, while the Ho/Pr superlattices are significantly less so. In the Ho/Pr superlattices, Pr is found to retain its bulk dhcp crystal structure even in thin layers (down to 6 atomic planes thick) sandwiched between...... thick layers of hcp Ho. In addition, neutron diffraction studies of the He/Pr superlattices have shown that the helical Ho magnetic order is not coherent through the dhcp Pr layers, in contrast to previous hcp/hcp superlattices Ho/Y, Ho/Lu and Ho/Er. The series of Ho:Pr alloy films has shown structural...

  13. Behaviour of Rare Earth Elements during the Earth's core formation

    Science.gov (United States)

    Faure, Pierre; Bouhifd, Mohamed Ali; Boyet, Maud; Hammouda, Tahar; Manthilake, Geeth

    2017-04-01

    Rare Earth Elements (REE) are classified in the refractory group, which means that they have a high temperature condensation and their volatility-controlled fractionation is limited to high-temperature processes. Anomalies have been measured for Eu, Yb and Sm, which are the REE with the lowest condensation temperatures in CAIs and chondrules (e.g. [1]). REE are particularly abundant in the sulfides of enstatite chondrites, 100 to 1000 times the CI value [e.g. 2,3], proving that these elements are not strictly lithophile under extremely reducing conditions. However by investigating experimentally the impact of Earth's core formation on the behavior of Sm and Nd, we have shown the absence of fractionation between Sm and Nd during the segregation of the metallic phase [4]. Recently, Wohlers and Wood [5] proposed that Nd and Sm could be fractionated in presence of a S-rich alloy phase. However, their results were obtained at pressure and temperature conditions below the plausible conditions of the Earth's core formation. Clearly, large pressure range needs to be covered before well-constrained model can be expected. Furthermore, our preliminary metal-silicate partitioning results show that Ce and Eu have higher metal/silicate partition coefficients than their neighboring elements, and that the presence of sulphur enhances the relative difference between partition coefficients. In this presentation, we will present and discuss new metal-silicate partition coefficients of all REE at a deep magma ocean at pressures ranging from those of the uppermost upper mantle ( 5 GPa) to a maximum pressure expected in the range of 20 GPa, temperatures ranging from 2500 to about 3000 K, and oxygen fugacities within IW-1 to IW-5 (1 to 5 orders of magnitude lower than the iron-wüstite buffer). We will discuss the effect of S, as well as the effect of H2O on the behaviour of REE during the Earth's core formation: recent models suggest that contrary to currently accepted beliefs, the

  14. Production of rare earth polishing powders in Russia

    International Nuclear Information System (INIS)

    Kosynkin, V.D.; Ivanov, E.N.; Kotrekhov, V.A.; Shtutza, M.G.; Grabko, A.I.

    1998-01-01

    in a suspension; polishing powder Ftoropol with addition of fluorine and higher contents of cerium dioxide (at least 70% by mass) that has a higher polishing ability and is attrition-proof, used for high-speed treatment of optical lenses, mirrors, TV screens and eyeglasses. The rare earth polishing powders made in Russia possess the following physico-chemical properties and performance characteristics; cerium dioxide content in solid REE solution - 50-90% by mass; F-ion content (in Ftoropol powder) - 8-14% by mass; non-REE content of sodium, calcium, strontium and iron impurities - at most 0.1% by mass of each element; natural radionuclide content of thorium, uranium, actinium, potassium-40 series, total standard specific activity - 0.45-0.85 Bq/g; - average particle size, 2.0-3.5 μm; density - 6.3-6.8 g/cm 3 ; pH of aqueous extract, 6-7; sedimentary stability - 10-20 minutes; polishing ability - 45-60 mg per 31 minutes (for polishing resin); abrasive inclusions - none. The report gives analysis of the. Russian powders compared against the best world analogues such as Cerox (Rhone Poulenc Company, France), Regipol (London and Scandinavian Division Chemical Company, England), etc. The analysis results imply, that the chief characteristics (granulometric composition, polishing ability and service life) of the Russian samples do not yield to the best foreign analogues, and in some properties (radionuclide content, sedimentary stability and scratching inclusions quantity) even surpass them

  15. Rare earth oxide doping in oxide cathodes

    International Nuclear Information System (INIS)

    Engelsen, Daniel den; Gaertner, Georg

    2006-01-01

    The effect on life performance and poisoning with O 2 by doping oxide cathodes with rare earth oxides and pseudo rare earth oxides, notably yttria, is qualitatively explained in terms of electrolysis of BaO during emission of electrons. Doped cathodes show less electrolysis and consume therefore less Ba during life: consequently, doped cathodes have a better life performance. However, the lower Ba-production makes doped cathodes more sensitive to oxygen poisoning. The experimentally found relation between conductivity and yttria concentration was the motive to propose a new model for the crystal imperfections in BaO. In this new imperfection model most Y 3+ -ions will combine with barium vacancies, therefore, the increase of the conductivity is modest and also the effect on the position of the Fermi level is modest. By assuming a combination of bulk and surface conductivity, the agreement between experiment and theory can be improved further

  16. Quantum Theory of Rare-Earth Magnets

    Science.gov (United States)

    Miyake, Takashi; Akai, Hisazumi

    2018-04-01

    Strong permanent magnets mainly consist of rare earths (R) and transition metals (T). The main phase of the neodymium magnet, which is the strongest magnet, is Nd2Fe14B. Sm2Fe17N3 is another magnet compound having excellent magnetic properties comparable to those of Nd2Fe14B. Their large saturation magnetization, strong magnetocrystalline anisotropy, and high Curie temperature originate from the interaction between the T-3d electrons and R-4f electrons. This article discusses the magnetism of rare-earth magnet compounds. The basic theory and first-principles calculation approaches for quantitative description of the magnetic properties are presented, together with applications to typical compounds such as Nd2Fe14B, Sm2Fe17N3, and the recently synthesized NdFe12N.

  17. Report 1: International Cooperation to Development of Strategy and R&D Collaboration for Substitution of Rare Earth Resources and Report 2: Development of Magnetocaloric Alloys without Critical Elements

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Ha [Ames Laboratory (AMES), Ames, IA (United States); Ott, Ryan [Ames Laboratory (AMES), Ames, IA (United States)

    2016-05-26

    A Memorandum of Understanding was signed between the Ames Laboratory and Korea Institute of Industrial Technology (KITECH) in April of 2011 to establish a close cooperative relationship of research on Rare Metals. The Ames Laboratory through its operating contractor, Iowa State University, and the KITECH, as one of the goals of a joint Memorandum of Understanding, made agreement on a Cooperative Research and Development Agreement (CRADA) for a personnel exchange in April of 2012. Ames Laboratory and KITECH would be jointly performing collaboration work in this cooperation as the Parties. The individual backgrounds and capabilities of the Parties are ideally suited to the successful execution of this work. The Ames Laboratory has a history spanning more than 60 years of pioneering work in rare-earth (RE) research. With its team of internationally recognized rare-earth experts, the Ames Laboratory is uniquely positioned to provide the knowledge, expertise and training necessary to help ensure a global leadership position for the United States in rare-earth research, development and applications. The KITECH was founded to promote technological capability of small and medium-sized enterprises in Korea and has a mission of supporting research on materials science and engineering in Korea. In 2009, Korea Institute for Rare Metals (KIRAM) at KITECH was established. KIRAM makes selection and funding decisions for technology projects for strategic rare metals, and provides oversight of R&D programs. The KIRAM is focusing on the commercialization and recycling of particular rare metals. In addition KIRAM will be coordinating government, local universities, and small to medium enterprises to facilitate R&D support for core technologies. KIRAM will be carrying them through to commercialization, and establishing new industry.

  18. Fascinating world of rare earth research

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.

    1977-01-01

    The first part of this paper concerns some of the notable events which occurred early in the author's career as a rare earther and some of the major events which took place in the two decades 1950 to 1970. The notable changes and advances in the rare earth research world since the 1971 Durham Conference are described in the second and largest part of the paper. The final portion is concerned with actinide developments since 1971

  19. Diagnostic study about lanthanides (rare earths)

    International Nuclear Information System (INIS)

    Ribeiro, G.F.

    1985-01-01

    The world situation of rare earths (lanthanides) is evaluated, and a comparison of the Brazilian situation in respect to other countries is established, concerning the following aspects: geology of mineral deposits; main sources, uses, reserves and production; their consumption, prices and state-of-art of geological researches and industrial processes for physical and chemical separation / concentration of these elements. (C.L.B.) [pt

  20. Mineralogy of the rare earth elements

    International Nuclear Information System (INIS)

    Clark, A.M.

    1984-01-01

    This paper contains mineralogic properties of the rare earth elements (REE). Notes are given on total REE abundances, distribution patterns, and modes of occurrence. References are confined as far as possible to papers containing usable REE data. The minerals are grouped alphabetically within each major cationic group. The paper includes an alphabetic table of mineral names, chemical formulas, crystal system and section number. It functions as a handy entrance to the mineralogic and bibliographic paper. (G.J.P.)

  1. Structure of small rare earth clusters

    International Nuclear Information System (INIS)

    Rayane, D.; Benamar, A.; Tribollet, B.; Broyer, M.; Melinon, P.

    1991-01-01

    Rare earth clusters are produced by the inert gas condensation technique. The observed size distribution shows large peaks at n=13, 19, 23, 26, 29, 32, 34, 37, 39, 45, .... The beginning of this sequence (up to 34) has been already observed in argon clusters and recently by our group in barium clusters; this sequence may be interpreted in terms of icosahedral structures corresponding to the addition of caps on a core icosahedron of 13 atoms. (orig.)

  2. Atomic masses of rare-earth isotopes

    International Nuclear Information System (INIS)

    Schmidt-Ott, W.D.; Kantus, R.; Runte, E.

    1981-01-01

    A survey is given of decay energies of rare-earth isotopes measured in electron-capture decay by relative Psub(K) ratios, ECsub(K)/β + , and EC/β + ratios. Atomic masses of A = 147 isotopes and of 146 Gd and 148 Dy were derived. The masses of these isotopes and of α-decaying precessors are compared with predictions of current mass formulae. The subshell closure at Z = 64 is shown for N = 82, and 84 isotones. (orig.)

  3. Epitaxial rare-earth superlattices and films

    International Nuclear Information System (INIS)

    Salamon, M.B.; Beach, R.S.; Flynn, C.P.; Matheny, A.; Tsui, F.; Rhyne, J.J.

    1992-01-01

    This paper reports on epitaxial growth of rare-earth superlattices which is demonstrated to have opened important new areas of research on magnetic materials. The propagation magnetic order through non-magnetic elements, including its range and anisotropy, has been studied. The importance of magnetostriction in determining the phase diagram is demonstrated by the changes induced by epitaxial clamping. The cyrstallinity of epitaxial superlattices provides the opportunity to study interfacial magnetism by conventional x-ray and neutron scattering methods

  4. China's Rare Earth Supply Chain: Illegal Production, and Response to new Cerium Demand

    Science.gov (United States)

    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.

  5. Iron-titanium-mischmetal alloys for hydrogen storage

    Science.gov (United States)

    Sandrock, Gary Dale

    1978-01-01

    A method for the preparation of an iron-titanium-mischmetal alloy which is used for the storage of hydrogen. The alloy is prepared by air-melting an iron charge in a clay-graphite crucible, adding titanium and deoxidizing with mischmetal. The resultant alloy contains less than about 0.1% oxygen and exhibits a capability for hydrogen sorption in less than half the time required by vacuum-melted, iron-titanium alloys.

  6. Hydrometallurgical method for recycling rare earth metals, cobalt, nickel, iron, and manganese from negative electrodes of spent Ni-MH mobile phone batteries; Metodo hidrometalurgico para reciclagem de metais terras raras, cobalto, niquel, ferro e manganes de eletrodos negativos de baterias exauridas de Ni-MH de telefone celular

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Vinicius Emmanuel de Oliveira dos; Lelis, Maria de Fatima Fontes; Freitas, Marcos Benedito Jose Geraldo de, E-mail: viniciusemmanuel@hotmail.com [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Quimica; Celante, Vinicius Guilherme [Instituto Federal do Espirito Santo (IFES), Aracruz, ES (Brazil)

    2014-07-01

    A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni-MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO{sub 4}){sub 2}.H{sub 2}O) and lanthanum sulfate (La{sub 2}(SO{sub 4}){sub 3}.H{sub 2}O) as the major recovered components. Iron was recovered as Fe(OH){sub 3} and FeO. Manganese was obtained as Mn{sub 3}O{sub 4}.The recovered Ni(OH){sub 2} and Co(OH){sub 2} were subsequently used to synthesize LiCoO{sub 2}, LiNiO{sub 2} and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques. (author)

  7. Microcapillary Features in Silicon Alloyed High-Strength Cast Iron

    Directory of Open Access Journals (Sweden)

    R.K. Hasanli

    2017-04-01

    Full Text Available Present study explores features of silicon micro capillary in alloyed high-strength cast iron with nodular graphite (ductile iron produced in metal molds. It identified the nature and mechanism of micro liquation of silicon in a ductile iron alloyed with Nickel and copper, and demonstrated significant change of structural-quality characteristics. It was concluded that the matrix of alloyed ductile iron has a heterogeneous structure with cross reinforcement and high-silicon excrement areas.

  8. Quantitative analysis of thorium in the presence of rare earth by X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Jesus, Camila S. de; Taam, Isabel; Vianna, Claudio A.

    2013-01-01

    The occurrence of Thorium in ores is normally associated to other elements such as Uranium and Cerium, as well as some Rare-Earths (RE). The separation of these elements by traditional analytic chemistry techniques is both time and reagent consuming, thus increasing the analysis cost. The hereby proposed method consists in the direct determination of Thorium in rare earths ores and compounds by X-ray fluorescence spectroscopy without any prior chemical separation from other matrix elements. This non-destructive technique is used to determine which elements are present in solid and liquid samples, as well as their concentrations. The studied matrix contains Lanthanum, Cerium, Praseodymium, Neodymium, Samarium, Gadolinium and Yttrium. This study evaluated the analytical lines of radiation emission for each rare earth contained in the matrix, comparing it to the Thorium main analytical line. The Thorium quantification was measured through the Th L line, where there is no influence or interference from the rare earths analytical lines. The studied samples are certified standards and the obtained results have been compared to Ethylenediaminetetraacetic acid (EDTA) titration results, an already well-established and widely trusted method. We also measured the matrix effect thus using complex rare earths liquor. This liquor contains also elements commonly found in monazites sands: phosphates, aluminum, iron. Obtained results state the efficiency of X-ray Fluorescence to determine Thorium in the presence of rare earths without any prior chemical separation. (author)

  9. Anthropogenic Cycles of Rare Earth Elements

    Science.gov (United States)

    Du, X.; Graedel, T. E.

    2009-12-01

    This research will develop quantitatively resolved anthropogenic cycles and in-use stocks for the rare earth metals specifically cerium, lanthanum and dysprosium in Japan, China, and the U.S. for the year of 2007. Rare earth elements (REE) is a group of 17 scare metals widely used in a growing number of emerging technologies and have been in high demand for emerging technologies as raw materials during past the three decades. New market participants from newly industrializing countries, primarily China, have had strong impacts on the demand of share. Consequently, the importance to sustain a reliable, steady, uninterrupted supply on global market triggered comprehensive research to recognize and understand the life cycles of rare earths. Moreover, because China plays a dominant role in mining production since 1990, it requires the assessment for the countries, which are almost completely dependent on imports from China with respect to rare earth resources. The study aims to analyze the flows and stocks of rare earth elements individually as elemental form in spite of their natural geological co-occurrence and mixed composition in applications. By applying the method of Material Flow Analysis (MFA) work has been done on evaluating current and historical flows of specific technologically significant materials, for example, copper, zinc, nickel, etc., determining the stocks available in different types of reservoirs (e.g., lithosphere, in-use) and the flows among the reservoirs, developing scenarios of possible futures of metal use, and assessing the environmental and policy implications of the results. Therefore, REE as a new target deserves inclusion because of its potential demand-supply conflict and importance to secure the competitive advantage of technical innovation in future. This work will generate a quantitatively resolved anthropogenic life cycle and in-use stocks for REE for the main target countries for a chosen year, 2007, providing flows and stocks from

  10. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

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

  11. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

    Mulyarchuk, I.F.; Voloshchenko, M.V.; Zen'kovich, E.G.; Sumenkova, V.V.; AN Ukrainskoj SSR, Kiev. Inst. Problem Lit'ya)

    1980-01-01

    The processes of preparation of the rare earths element sum from apatite concentrate of the Khibins, connected with preliminary extraction of rare earth phosphates from nitric acid extract using solvent extraction or direct precipitation from the extract by solution of potassium and ammonium fluorides. The sequence of the processes of the first variant is the following: solvent extraction of rare earths by tributylphosphate from clarified nitric acid extract of apatite with subsequent reextraction of rare earths with water and precipitation of rare earth phosphates from aqueous solution during neutralization by ammonia. In case of fluoride preparation from rare earth phosphate the main attention is paid to precipitation and filtration of fluorides. Technological scheme and cost price of industry for the production of 1800 t of rare earth trifluorides a year are calculated. When taking account of TBP losses according to its solubility the industry cost price is 1O times lower the modern cost of rare earth fluorides

  12. Effect of rare earth oxide additives on the performance of NiMH batteries

    International Nuclear Information System (INIS)

    Tanaka, Toshiki; Kuzuhara, Minoru; Watada, Masaharu; Oshitani, Masahiko

    2006-01-01

    To date, we have performed research on nickel-metal hydride (NiMH) batteries used in many applications and have found that addition of rare earth oxides to the nickel electrode and the hydrogen-storage alloy (MH) electrode improves battery performance significantly. Because heavy rare earth oxides of such as Er, Tm, Yb and Lu have remarkable properties that shift the oxygen evolution overpotentials of nickel electrodes to more noble potentials, it is possible to improve high-temperature charge efficiency of nickel-metal hydride secondary batteries by adding them to nickel electrodes. Furthermore, addition of heavy rare earth oxides to MH electrodes depresses an acceleration of the alloy corrosion and improves service life of the battery at high temperatures. Accordingly, addition of heavy rare earth oxides is effective for NiMH batteries used in high-temperature applications such as electric vehicles (EVs), hybrid vehicles (HEVs) and rapid charge devices. In this study, we discussed how the addition of heavy rare earth oxides affects NiMH battery characteristics

  13. Samarium-cobalt type rare earth permanent magnets

    International Nuclear Information System (INIS)

    Kamat, S.V.

    2014-01-01

    Permanent magnets are one of the oldest and largest applications of magnetic materials and form an integral part of our modern industrial society. They belong to a special class of functional materials and are characterized for remanence (flux output from the magnet), coercivity (resistance to demagnetization) and energy product (material energy density) from the second quadrant of the magnetic hysteresis loop. The reliability, stability, size, weight, cost and performance of many electro-technical devices depend mainly on the properties of permanent magnets used in them. There are three important families of permanent magnets viz., Ferrites, Alnicos and Rare Earth Permanent Magnets (REPMs) with energy product values ranging from 3 to 50 MGOe and among the front ranking high performance REPMs, SmCo 5 , Sm 2 Co 17 type and NdFeB alloys are technologically the most important materials. They are used in a wide range of applications ranging from consumer products to very specialized areas of tele-communications, microelectronics, defence, space, avionics etc. While NdFeB has the highest energy product, Sm-Co based magnets are preferred for most critical applications where temperature stability of magnetic properties is essential because of their significantly higher Curie temperatures. In this presentation some of the key challenges associated with these Sm-Co based rare earth permanent magnets will be highlighted. (author)

  14. Distribution of rare earths in liver of mice administered with chloride compounds of 12 rare earths

    International Nuclear Information System (INIS)

    Shinohara, A.; Chiba, M.; Inaba, Y.

    1998-01-01

    Full text: Rare earths are used in high technology field, however, the information on their biological effects are not sufficient. The behaviour of rare earths in biology is of interest in connection with their toxicity. In the present study, the distribution of rare earths in liver of mice administered with these elements was investigated. The effects on Ca and other biological essential elements were also determined. Male mice (5 weeks old) were injected with one of 12 kinds of rare earths (chlorides of Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb) at the dose of 25 mg/KXg body weight. After 20 hours of administration, mice were sacrificed, then liver and other organs were taken out. Liver was homogenized and separated by centrifugation. The concentrations of rare earths administered were measured by microwave-induced plasma-mass spectrometry (MIP-MS) after acid digestion. The concentrations of administered elements in whole liver were about 100μg/g (wet weight), where the difference between elements was few. Distribution amounts of elements administered in four fractions were following order; 700μg precipitate > mitocondrial fraction > microsomal fraction > cytosol. The relative contents in these fractions, however, was different depending on the element administered. Calcium concentrations in liver of administered mice were higher than those of control mice. Increase of Ca concentrations were observed in all four fractions and the increase ratio was also dependent on the elements administered

  15. Rare earth elements behavior in Peruibe black mud

    Energy Technology Data Exchange (ETDEWEB)

    Torrecilha, Jefferson K.; Carvalho, Leandro P.; Gouvea, Paulo F.M.; Silva, Paulo S.C. da, E-mail: jeffkoy@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Rare earth elements in sediments have been used as powerful tools for environmental studies because of their behavior during geochemical processes and are also widely accepted as reliable provenance tracers because they are largely water-immobile and thus behave conservatively during sedimentary processes. The Peruibe Black Mud (PBM) is a sedimentary deposit originated from the interactions of marine sediments and organic matter in an estuarine environment that originates a peloid currently used for medicinal purposes. The objective of this study was to examine rare earth elements pattern distribution in the Peruibe black mud sedimentary deposit as a proxy for its geochemical development. Elemental ratios such as LaN/YbN, Th/U and La/Th were determined and a normalization of the mean rare earth elements concentrations in the samples related to NASC indicates that the light (La to Eu) rare earth elements present values close to the unity while the heavy (Tb to Lu) rare earth elements are depleted related to NASC. It can be observed that the light rare earth elements present enrichment values slightly enriched over the unity while the heavy rare earth elements present values generally below the unity reflecting the enrichment of the light rare earth elements over the heavy rare earth. Rare earth elements concentrations determined in Peruibe black mud samples showed a distribution similar to that found in the NASC for the light rare earth elements and depleted for the heavy rare earth elements. (author)

  16. Rare earth elements behavior in Peruibe black mud

    International Nuclear Information System (INIS)

    Torrecilha, Jefferson K.; Carvalho, Leandro P.; Gouvea, Paulo F.M.; Silva, Paulo S.C. da

    2015-01-01

    Rare earth elements in sediments have been used as powerful tools for environmental studies because of their behavior during geochemical processes and are also widely accepted as reliable provenance tracers because they are largely water-immobile and thus behave conservatively during sedimentary processes. The Peruibe Black Mud (PBM) is a sedimentary deposit originated from the interactions of marine sediments and organic matter in an estuarine environment that originates a peloid currently used for medicinal purposes. The objective of this study was to examine rare earth elements pattern distribution in the Peruibe black mud sedimentary deposit as a proxy for its geochemical development. Elemental ratios such as LaN/YbN, Th/U and La/Th were determined and a normalization of the mean rare earth elements concentrations in the samples related to NASC indicates that the light (La to Eu) rare earth elements present values close to the unity while the heavy (Tb to Lu) rare earth elements are depleted related to NASC. It can be observed that the light rare earth elements present enrichment values slightly enriched over the unity while the heavy rare earth elements present values generally below the unity reflecting the enrichment of the light rare earth elements over the heavy rare earth. Rare earth elements concentrations determined in Peruibe black mud samples showed a distribution similar to that found in the NASC for the light rare earth elements and depleted for the heavy rare earth elements. (author)

  17. Rare earth elements materials production from apatite ores

    International Nuclear Information System (INIS)

    Anufrieva, A V; Buynovskiy, A S; Makaseev, Y N; Mazov, I N; Nefedov, R A; Sachkov, V I; Valkov, A V; Andrienko, O S; Stepanova, O B

    2016-01-01

    The paper deals with the study of processing apatite ores with nitric acid and extraction of the rare earth elements. The rare earth elements can be successfully separated and recovered by extraction from the nitrate- phosphate solution, being an tributyl phosphate as extraction agent. The developed scheme of the processing apatite concentrate provides obtaining rare earth concentrates with high qualitative characteristics. (paper)

  18. Rare earth permanent magnet with easy magnetization

    International Nuclear Information System (INIS)

    Kim, A.S.; Camp, F.E.

    1998-01-01

    Rare earth permanent magnets have high energy products and coercivities, and thus the volume miniaturization of magnetic devices has been possible with improved magnetic performance. Although the high energy products of these rare earth permanent magnets provide substantial advantages for magnetic design and application, the strong magnetic force of the magnetized magnets makes assembly difficult. Therefore, a special device is needed to assemble the magnetized magnets. On the other hand, unmagnetized magnets are assembled and then they are magnetized. The assembled magnets are generally more difficult to magnetize than unassembled magnets because a much less effective magnetic field may be applied to them. This is particularly true for the rare earth permanent magnets because they usually need a much higher magnetic field to be fully magnetized than alnico or ferrite magnets. To obtain optimum magnetic properties, the required minimum magnetizing fields for SmCo 5 , Sm 2 TM 17 and Nd 2 Fe 14 B magnets were reported as 25-30 kOe, 45-60 kOe and 25-30 kOe, respectively. If the required magnetizing field for full saturation could be lowered, the effective utilization of magnetic properties would be maximized and the magnetic design option could be expanded with reduced restrictions. To meet this demand, we have sought to lower the field required for full magnetic saturation, and found that an increase in Dy content in R-(Fe,Co,Cu)-B type magnets lowers the field required for full saturation as well as improves the temperature stability. By increasing the H ci with Dy addition from 14 kOe to 24 and 34 kOe, the field required for full magnetic saturation decreases from about 20 to 15 and 10 kOe, respectively. This dual benefit will open up new application areas with more freedom for magnet design options. The mechanism for the lower magnetizing fields will be discussed. (orig.)

  19. Port Pirie rare earths plant stage 3

    International Nuclear Information System (INIS)

    1990-08-01

    SX Holdings Limited intends to establish a rare earths plant at Port Pirie, South Australia. The proposal involves three stages of development, Stage 3 being to develop a monazite cracking plant and associated rare earths separation facility with the capacity to process up to 8,000 t/a of monazite-type ores. The proposed initial capacity is 4,000 t/a. This Draft Environmental Impact Statement relates to Stage 3 and is based on a monazite processing capacity of 8,000 t/a. The justification of the project is given in terms of use and the market for rare earths, the economic and environmental benefits of the proposal, the site selection process, site rehabilitation, and the consequences of not proceeding. A detailed description of the project is given, including the treatment process, site development and facilities, the supply of raw materials, product and waste handling, transport and storage, plant commissioning, operation and decommissioning, construction and staffing. The environmental issues entailed in the proposed development are discussed and include social effects, land use and infrasturcture considerations, risk management and transport. Occupational and environmental radiation issues, including assessments of exposure pathways and doses, management and monitoring, disposal of monosite residue are also discussed. It is estimated that the effects of disposal of 2,330 t/year of radioactive slurry in the sub-aerial tailing disposal system at Olympic Dam will be negligible. Moreover, the gamma dose increases would not result in any significant increase in occupational exposures. 38 refs., tabs., ills

  20. Enhanced separation of rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-01

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

  1. Luminescence studies of rare earth doped dosimeters

    International Nuclear Information System (INIS)

    Karali, T.

    1999-10-01

    The main objective of this thesis has been to address the applications and fundamentals of thermoluminescence (TL) and to contribute to existing knowledge about TL mechanisms in materials which are applied as radiation dosimeters. This issue has been explored for a long time but the mechanisms lack completeness and certainty. TL, Radioluminescence (RL) and Radio-thermoluminescence (RLTL) measurements have been conducted on a high sensitivity TL spectrometer both at low (30-290 K) and high (25-400 deg. C) temperatures, and different heat treatments (furnace and laser) were conducted in order to study the possible impurity clustering which changes the TL spectra and efficiency of the dosimeters. Studies have been based on three different host structure, namely sulphate, borates and zircon. The spectra of calcium sulphate samples doped with Tm 3+ and Dy 3+ at different concentration were examined using TL, RL and RLTL. Similar procedures were applied to the borate samples. Modifications of the material by thermal treatments convert the state of dispersion of the rare earth ions between isolated, pair or defect clusters, which alter the dosimeter efficiency. In some cases, modified geometries are detectable by movement of the line emissions such as for quenched samples which are attributable to new microcrystal line phases. The study of co-doped samples showed unequivocal evidence of a glow peak displacement of the two dopants within a single sample. This result supports the new view that RE 3+ ions could form part of a complex defect acting as both charge trap and recombination centres. Pulsed laser heating with a UV laser changed the glow curve shape and lead to strong signals. The detailed mechanisms for this process are discussed. The RL and TL spectra of synthetic zircon crystals doped with different RE 3+ ions (Pr, Sm, Eu, Gd, Ho, Dy, Er, and Yb) and phosphorus are reported. Even though there is some intrinsic emission from the host lattice the major signals are

  2. Alternative value chains for rare earths

    DEFF Research Database (Denmark)

    Machacek, Erika; Fold, Niels

    2014-01-01

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

  3. Aluminium alloys containing iron and nickel

    International Nuclear Information System (INIS)

    Coriou, H.; Fournier, R.; Grall, L.; Hure, J.; Herenguel, J.; Lelong, P.

    1958-01-01

    The first part of this report addresses mechanism, kinetics and structure factors of aluminium alloys containing iron and nickel in water and high temperature steam. The studied alloys contain from 0.3 to 0.7 per cent of iron, and 0.2 to 1.0 per cent of nickel. Corrosion resistance and corrosion structure have been studied. The experimental installation, process and samples are presented. Corrosion structures in water at 350 C are identified and discussed (structure of corrosion products, structure of metal-oxide interface), and then in steam at different temperatures (350-395 C). Corrosion kinetics is experimentally studied (weight variation in time) in water at 350 C and in steam at different temperatures. Reactions occurring at over-heated steam (more than 400 C) are studied, and the case of welded alloys is also addressed. The second part addresses the metallurgical mechanism and processes influencing aluminium alloy resistance to corrosion by high temperature water as it appeared that separated phases protect the solid solution through a neighbourhood action. In order to avoid deep local corrosions, it seems necessary to multiply protective phases in an as uniform as possible way. Some processes enabling this result are described. They belong to conventional metallurgy or to powder metallurgy (with sintering and extrusion)

  4. Preparation of ammonium sulfate, calcium oxide and rare earth concentrate from phospho-gypsum

    International Nuclear Information System (INIS)

    Andrianov, A.M.; Rusin, N.F.; Dejneka, G.F.; Zinchenko, T.A.; Burova, T.I.

    1978-01-01

    A technological scheme is proposed which gives ammonium sulfate, purified (from admixtures of silicon, iron, titanium, aluminium) calcium oxide with direct yield of calcium 91% and rare-earth concentrate, containing 5.6% of Ln 2 O 3 with direct yield of 99.5%

  5. Monazite upgradation and production of high pure rare earths

    International Nuclear Information System (INIS)

    Asnani, C.K.; Mohanty, D.; Kumar, S.S.

    2014-01-01

    Rare earth extraction from monazite and further processing of mixed rare earth chlorides for producing individual high pure rare earths involves a complex flowsheet based on solvent extraction process. Apart from involving multiple extractions, scrubbing and stripping operations, the flowsheet requires optimization of critical parameters such as solvent molarity, solvent saponification level and recycling of product solutions as reflux to ensure preferential upload of required rare earths to generate high purity product. This paper tracks monazite flow from the raw sand feed through to the monazite product and its processing to generate rare earths of internationally acceptable quality

  6. ThMn12-type phases for magnets with low rare-earth content: Crystal-field analysis of the full magnetization process.

    Science.gov (United States)

    Tereshina, I S; Kostyuchenko, N V; Tereshina-Chitrova, E A; Skourski, Y; Doerr, M; Pelevin, I A; Zvezdin, A K; Paukov, M; Havela, L; Drulis, H

    2018-02-26

    Rare-earth (R)-iron alloys are a backbone of permanent magnets. Recent increase in price of rare earths has pushed the industry to seek ways to reduce the R-content in the hard magnetic materials. For this reason strong magnets with the ThMn 12  type of structure came into focus. Functional properties of R(Fe,T) 12 (T-element stabilizes the structure) compounds or their interstitially modified derivatives, R(Fe,T) 12 -X (X is an atom of hydrogen or nitrogen) are determined by the crystal-electric-field (CEF) and exchange interaction (EI) parameters. We have calculated the parameters using high-field magnetization data. We choose the ferrimagnetic Tm-containing compounds, which are most sensitive to magnetic field and demonstrate that TmFe 11 Ti-H reaches the ferromagnetic state in the magnetic field of 52 T. Knowledge of exact CEF and EI parameters and their variation in the compounds modified by the interstitial atoms is a cornerstone of the quest for hard magnetic materials with low rare-earth content.

  7. Thermoelectric transport in rare-earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Ulrike

    2007-07-01

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

  8. Magnetoelastic interaction in rare earth systems

    International Nuclear Information System (INIS)

    Dohm, V.

    1975-01-01

    A theory of rotationally invariant spin-lattice interactions in rare earth systems is presented. It is shown that rotational invariance to leading order is ensured only if rotational interactions of first and second order in the displacements are included simultaneously in the spin-lattice Hamiltonian. The rotational second-order interactions yield effects which are as large as those of the linear rotational interaction. It is pointed out that a corresponding statement should hold also for pure strain interactions. The phonon Green's function is calculated for the paramagnetic phase of rare earth systems. It is found that in an applied magnetic field the rotational interactions cause measureable changes of the phonon dispersion and the sound velocity even for cubic symmetry. These effects turn out to be of the same order of magnitude as the conventional field-dependent strain effects and are qualitatively different from the latter. The results of our theory are illustrated by the example of SmSb, and quantitative predictions for the transverse sound velocities are given. (orig.) [de

  9. Costs and benefits of rare earth screens

    International Nuclear Information System (INIS)

    Taylor, F.E.

    1977-01-01

    The British Institute of Radiology has submitted evidence (Royal Commission on Environmental Pollution, 1976, Sixth Report, Nuclear Power and the Environment. Cmnd 6618, HMSO, London) leading to the conclusion that the introduction of rare earth screens in medical radiography is not financially practical at present in the U.K. This conclusion is questioned. The cost of reducing the genetic dose from medical radiography should be compared with the costs of reducing that from other sources such as nuclear power wastes, since the risks are to future generations in both cases. The cost of reducing public exposure by the use of rare earth screens in U.K. hospitals is calculated to be about Pound1 per man-rad; a total annual genetic collective dose of nearly 300,000 man-rad could be saved. An anomalous situation is presented by the great discrepancies between this cost, and published estimates both of the cost of the detriment associated with the genetic collective dose and of the value incorporated into the design objective for nuclear reactors. (U.K.)

  10. Thermoelectric transport in rare-earth compounds

    International Nuclear Information System (INIS)

    Koehler, Ulrike

    2007-01-01

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

  11. Emerging industrial processes for low grade rare earth mineral concentrates

    International Nuclear Information System (INIS)

    Soldenhoff, Karin; Ho, Elizabeth

    2015-01-01

    Historically rare earth recovery has mainly been derived from the processing of monazite, bastnasite and xenotime containing ores amenable to beneficiation, yielding high grade mineral concentrates. A notable exception is the recovery of heavy rare earths from ionic clays in Southern China. Recently, projects are being proposed to treat a range of mineral concentrates which tend to be lower grade with wide ranging modal mineralogy for rare earths and associated gangue minerals. This has a significant impact on processing routes. This paper discusses processes proposed for emerging rare earth producers and how different projects have responded to particular challenges including: Control of phosphorous due to the presence of xenotime or monazite type minerals; Control of phosphorous due to the presence of rare earth containing apatite; Rare earth recovery from polymetallic ores; Control of radionuclides in rare earth processing, etc.

  12. Study on Magnetic Responsibility of Rare Earth Ferrite/Polyacrylamide Magnetic Microsphere

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming; Wang Zhifeng; Zhang Hong; Dai Shaojun; Qiu Guanming; Okamoto Hiroshi

    2005-01-01

    In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of microsphere relates to magnetic moment of rare earth ion, and it can be improved by the addition of dysprosium ion of high magnetic moment. Dysprosium content has an effect on magnetic responsibility of dysprosium ferrite/polyacrylamide magnetic microsphere. The microsphere displays strong magnetic responsibility when the molar ratio of Dy3+/iron is 0.20.

  13. Effect of Rare Earth Element on Microstructure and Properties of in situ Synthesized TiB2/Al Composites

    Directory of Open Access Journals (Sweden)

    QU Min

    2018-03-01

    Full Text Available The effect of rare earth element Ce, Sc and Er on TiB2 particles and matrix alloy micros-tructure of TiB2/Al composites was studied with in situ synthesis method. It shows that the addition of rare earth element improves the microstructure and properties of TiB2/Al composites notably. The particles of TiB2 are relatively homogenously distributed as adding 0.3% (mass fraction rare earth element Sc and Er, moreover, it is Er that refines the microstructure of matrix alloy most significantly, then is Sc. Similarly, it is demonstrated that the addition of Sc and Er results in better tensile strength, which is enhanced by 32% and 31%, respectively; the addition of Er also leads to the best ductility by 85% with optimal tensile property. Meanwhile, fracture morphology analysis reveals that the fracture of the composites is microporous gathered ductile fracture when adding Sc and Er. Finally, it is verified that the mechanism of rare earth element on composites lies in two aspects:one is that the addition of rare earth element improves the wettability of the composites and suppresses the agglomeration of TiB2 particles; the other is that the addition of rare earth element refines the microstructure of matrix alloy and then improves the tensile strength of the composites.

  14. Rare earth element patterns in nigerian coals

    International Nuclear Information System (INIS)

    Ewa, I.O.B.; Elegba, S.B.

    1996-01-01

    Rare Earth Elements (REE's) retain group coherence in their environment and are therefore useful geochemical markers. We report the pattern of ten REE's (La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu) determined by Instrumental Neutron Activation Analysis (INAA) for coals obtained from eight mines in Nigeria, namely, Okaba, Enugu, Ogbete, Onyeama, Gombe, Lafia, Asaba and Afikpo. Our results show the existence of fractionations with the highest index of 13.19 for Lafia coal, depletion in HREE, negative Eu anomaly for most of the coals, REE patterns that are consistent with chondritic trends; prominent (Eu/Eu * ) cn for Okaba and Gombe coals. Variations in geochemical data observed could suggest strong departures from band metamorphism during the coalification events of the Benue Trough geosynclines, where the coal deposits are all located. (author) 14 refs., 2 figs., 3 tabs

  15. Double selenates of rare earths and ammonium

    International Nuclear Information System (INIS)

    Iskhakova, L.D.; Kozlova, N.P.; Makarevich, L.G.

    1991-01-01

    Double selenates of rare earths with ammonium were prepared in result of crystallization. It is shown that NH 4 Ln(SeO 4 ) · nH 2 O crystalline hydrates are presented by penta-and trihydrates. Existance of two modifications was revealed for NH 4 Ln(SeO 4 ) · 5H 2 O: monoclinic form of NH 4 La(SeO 4 ) 2 · 5H 2 O, isostructural RbCe(SeO 4 ) 2 · 5H 2 O, and earlier unknown rhombic form of salts with Ln = Pr, Nd. Trihydrates with Ln = Sm-Yb belong to structural type of RbNd(SeO 4 ) 2 · 3H 2 O. Anhydrous salts NH 4 Ln(SeO 4 ) 2 are isostructural with monoclinic KNd(SO 4 ) 2 modification. Lattice parameters of binary selenates are presented

  16. Ecological effect of rare earth elements

    International Nuclear Information System (INIS)

    Hu Aitang; Zhou Quansuo; Zheng Shaojian; Zhai Hai; Zhao Xiulan; Pang Yonglin; Wang Yuqi; Sun Jingxin; Zhang Shen; Wang Lijun

    1997-01-01

    Water and soil culture were carried out to study the ecological effect of rare earth elements (REEs) in the aspect of plant-soil system. Contents of REEs were determined by instrumental neutron activation analysis (INAA). There was a limit to REEs-tolerance of crops, which differed with the development periods of plant and soil types. The REEs concentration in plant, especially in root, was marked related to the concentration in culture material. Beyond the concentration-limit appeared phototoxicity. The chemical behavior of REEs in plants and soils varied with soil types and elements. The bio-availability of REEs in soil mainly depended on the exchangeable fraction of REEs affected strongly by the physi-chemical properties of soils

  17. Processing of monazite at the rare earth division,Udyogamandal

    International Nuclear Information System (INIS)

    Narayanan, N.S.; Thulasidoss, S.; Ramachandran, T.V.; Swaminathan, T.V.; Prasad, K.R.

    1988-01-01

    The processing techniques adopted at the Rare Earth Division of the Indian Rare Earths Limited at Udyogamandal, for the production of rare earth compounds of various compositions and purity grades are reviewed. Over 100 different compounds are produced and marketed, and these include mixed rare earths chloride, crude thorium concentrate, cerium oxide, cerium hydrate, rare earths carbonate, didymium salts and individual rare earth oxides and salts. Also, the trisodium phosphate obtained as byproduct in the processing of monazite, is recovered and marketed. The process scheme for monazite essentially involves alkaline digestion of ground monazite, removal of the by-product trisodium phosphate, separation of thorium through preferential dissolution of rare earths hydroxide in hydrochloric acid under controlled pH and temperature conditions followed by purification, and evaporation of the chloride solution to yield pure rare earths chloride. Part of the chloride is utilised for the production of individual rare earth compounds after separation by solvent extraction and ion exchange processes. Individual rare earth compounds of 99.99 %+ purity are regularly produced to cater to the demand within the country. (author) 8 figs., 1 tab

  18. Magnetic properties of rare-earth intermetallics

    International Nuclear Information System (INIS)

    Kirchmayr, H.

    1978-01-01

    A review is given of the concepts at present used to explain the magnetic properties of rare-earth intermetallics which have been the subject of numerous investigations in recent years. Rare-earth intermetallics with the formula Rsub(a)Bsub(b) are divided according to the magnetic moment of the B atom(s). If there is no magnetic moment present at the B-site, the exchange is only between the magnetic moments at the R-sites, which can only be of indirect character. One possible model is still the RKKY model, although it usually gives in practice only a qualitative description of the magnetic properties. Typical R-B compounds with the B-moment equal to zero are (for instance) the RA1 2 compounds, and related compounds such as the RZn and RCd compounds as well as compounds of the general formula RB 2 (B = Ni, Os, Ir, Pd, Ru or Rh). Of all intermetallics with nonzero B-moment, the R-3d intermetallics are the most important. These intermetallics can be formed with Mn, Fe, Co and Ni. In these systems there exist in principle three interactions, namely between the R-R, R-3d and 3d-3d atoms. The most important is usually the latter interaction. After a short discussion of the crystal structures which occur with R-3d intermetallics, the basic magnetic properties of R-3d intermetallics are presented. These properties are discussed with respect to the formation of a magnetic moment at the 3d site in the framework of present band theories. Special emphasis is given to a discussion of the localized or itinerant character of 3d electrons. (author)

  19. Studies on neutron irradiation effects of iron alloys and nickel-base heat resistant alloys

    International Nuclear Information System (INIS)

    Watanabe, Katsutoshi

    1987-09-01

    The present paper describes the results of neutron irradiation effects on iron alloys and nickel-base heat resistant alloys. As for the iron alloys, irradiation hardening and embrittlement were investigated using internal friction measurement, electron microscopy and tensile testings. The role of alloying elements was also investigated to understand the irradiation behavior of iron alloys. The essential factors affecting irradiation hardening and embrittlement were thus clarified. On the other hand, postirradiation tensile and creep properties were measured of Hastelloy X alloy. Irradiation behavior at elevated temperatures is discussed. (author)

  20. ANALYSIS OF KINETICS OF CAST IRON ALLOYING THROUGH SLAG PHASE

    Directory of Open Access Journals (Sweden)

    O. S. Komarov

    2012-01-01

    Full Text Available The mechanism of cast iron alloying through slag phase due to use of nickel and copper oxides is considered and the analysis of kinetics regularity of alloying in case of absence of fuse in the form of milled cast-iron chips in slag and at their presence in it is carried out.

  1. Enhanced pinning in mixed rare earth-123 films

    Science.gov (United States)

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

    2009-06-16

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

  2. A study on dehydration of rare earth chloride hydrate

    International Nuclear Information System (INIS)

    Cho, Yong Zun; Eun, Hee Chul; Son, Sung Mo; Lee, Tae Kyo; Hwang, Taek Sung

    2012-01-01

    The dehydration schemes of rare earth (La, Ce, Nd, Pr, Sm. Eu, Gd, Y) chloride hydrates was investigated by using a dehydration apparatus. To prevent the formation of the rare earth oxychlorides, the operation temperature was changed step by step (80→150→230 degree C) based on the TGA (thermo-gravimetric analysis) results of the rare earth chloride hydrates. A vacuum pump and preheated Ar gas were used to effectively remove the evaporated moisture and maintain an inert condition in the dehydration apparatus. The dehydration temperature of the rare earth chloride hydrate was increased when the atomic number of the rare earth nuclide was increased. The content of the moisture in the rare earth chloride hydrate was decreased below 10% in the dehydration apparatus.

  3. Study on the extraction of rare earth elements in liquid bismuth

    International Nuclear Information System (INIS)

    Harada, M.; Adachi, M.; Kai, Y.; Koike, K.

    1987-01-01

    Three factors, which are important for the extraction of rare earth elements in liquid bismuth - molten salt system, were studied, i. e., the equilibrium distribution of neodymium, samarium and bismuth between molten LiCl - liquid Bi-Li alloys, the extraction rate of rare earths, and the characteristics of the extractor with drop dispersion. The rare earth elements were extracted through redox reactions. In high range of Li-mole fraction in the alloy phase, X Li , the distribution of neodymium and bismuth in the salt phase markedly increased as X Li increased. The anomalous increase is attributed to the formation of the compound comprised of Nd, Li, Bi and oxygen in the salt phase. The redox reaction processes were very fast and the extraction rates for rare earths are controlled by the diffusion processes of the solute and the metallic lithium. The process for the formation of liquid metal drops in the continuous phase is predictable from semiempirical correlations reported for aqueous solution - organic solvent systems. The height of droplet bed being accumulated on drop settling portion is predictable from the coalescence time of single drop to a flat metal interface. The coalescence of metal drop to clean interface was very fast. The extractor type of liquid metal dispersion in molten salt is suitable for the extraction process in the fuel reprocessing of MSR or MSBR. (author)

  4. Generalized phase diagram for the rare-earth elements: Calculations and correlations of bulk properties

    International Nuclear Information System (INIS)

    Johansson, B.; Rosengren, A.

    1975-01-01

    A ''generalized'' phase diagram is constructed empirically for the lanthanides. This diagram makes it possible, not only in one picture, to assemble a lot of information but also to predict phase transitions not yet experimentally accessible. Further, it clearly illustrates the close relation between the members of the lanthanide group. To account for some of its features, the pseudopotential method is applied. The trend in crystal structure through the lanthanide series can thereby be qualitatively accounted for, as can the trend in crystal structure for an individual element, when compressed. A scaling procedure makes it possible to extend the treatment to elements neighboring the lanthanides in the Periodic Table. In total 25 elements are considered. An atomic parameter f (relatable to the pseudopotential) is introduced, by means of which different phase transitions, both for an individual rare-earth element and intra-rare-earth alloys, can be correlated to certain critical values of this parameter. A nonmagnetic rare-earth series (Sc, Lu, Y, La, and Ac) is introduced and the occurrence of superconductivity is discussed with special emphasis on the pressure dependence of the transition temperature. This temperature can be correlated to the above-mentioned parameter f, both for intra-rare-earth alloys and pure elements at different pressures. The correlation implies that actinium is a superconductor with a critical temperature which could be as high as (11--12) degree K

  5. Leaching of rare earth elements from bentonite clay

    OpenAIRE

    van der Watt, J.G; Waanders, F.B

    2012-01-01

    Due to increasing concerns of global rare earth element shortfalls in the near future, possible alternative sources of rare earth elements have recently become of economic interest. One such alternative is decanting acid mine water originating primarily from abandoned old mines in the Witwatersrand region of the Republic of South Africa. In this study, a novel way of rare earth element removal from the acid mine drainage was employed, making use of bentonite clay, which has very good adsorben...

  6. Enzymatic determination of rare earth elements using pyrophosphatases

    International Nuclear Information System (INIS)

    Shekhovtsova, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive(determination limit 8x10 -6 -4x10 -4 μ g/m) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E.Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  7. Enzymatic determination of rare earth elements by use of pyrophosphotases

    International Nuclear Information System (INIS)

    Shekhovtseva, T.N.; Pirogova, S.V.; Fedorova, O.M.; Dolmanova, I.F.; Bajkov, A.A.

    1993-01-01

    A highly sensitive (determination limit 8 x 10 -6 - 4 x 10 -4 μg/ml) and selective enzymatic method for determination of rare earth elements has been developed. The method is based on inhibition action of rare earths on the catalytic activity of pyrophosphates isolated from bakery geast and E. Coli. The mechanism of the rare earth element action, corresponding to competitive inhibition, has been established

  8. Distribution characteristics of rare earth elements in plants from a rare earth ore area

    International Nuclear Information System (INIS)

    Zhang, Z.Y.; Wang, Y.Q.; Li, F.L.; Xiao, H.Q.; Chai, Z.F.

    2002-01-01

    The contents of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in various plant species taken from a rare earth ore area were determined by instrumental neutron activation analysis. For a given plant, the REE patterns in root, leaf and host soil are different from each other. The REE distribution characteristics in roots of various species are very similar and resemble those in the surface water. The results of this study suggest that there is no significant fractionation between the REEs during their uptake by the plant roots from soil solution. However, the variation of the relative abundance of individual REE occurs in the process of transportation and deposition of REEs in plants. (author)

  9. Cermets based on rhenium and rare earth element oxides

    International Nuclear Information System (INIS)

    Varfolomeev, M.B.; Velichko, A.V.; Zajtseva, L.L.; Shishkov, N.V.

    1977-01-01

    The reduction of perrhenates of rare earth elements and of yttrium by hydrogen and the subsequent sintering have yielded cermets based on rhenium and rare earth element oxides inherent in which are more disperse and homogeneous structures than those of the ''molecular'' rare earth element-Tc cermets. The dispersity of cermets increases in the rare earth elements series from La to Lu. The microhardness of the Re phase in cermets is 490 kgf/mm 2 ; the total microhardness of a cermet is substantially higher

  10. Rare earth impact on glass structure and alteration kinetics

    International Nuclear Information System (INIS)

    Molieres, E.

    2012-01-01

    This work is related to the question of the geological deep repository of high-level waste glass. These wastes include fission products and minor actinides, elements which can be simulated by rare earths. As new glass compositions could enable increased rare earth concentrations, it is crucial to know and understand rare earth impact on glass structure on the one hand, and on glass alteration kinetics or their incorporation into an altered layer. This work studied simplified borosilicate glasses in order to limit synergetic effects between rare earths and other elements. Various complementary techniques were used to characterize pristine and altered glasses (solid-high resolution NMR, Raman spectroscopy, fluorescence, SIMS, SAXS). Firstly, the structural role of a rare earth is discussed and is compared to a calcium cation. The local environment of rare earths is also probed. Secondly, rare earth (nature and concentration) impact on several alteration regimes was studied (initial rate, rate drop). Then, after alteration, rare earth elements being retained within the altered layer, the structural impact of rare earth elements (and their local environment) in this alteration layer was also investigated. (author) [fr

  11. Rare earth element abundances and distribution patterns in plant materials

    International Nuclear Information System (INIS)

    Aidid, S.B.

    1994-01-01

    Eight out of the fourteen rare earth elements were estimated from the leaves of Pelthophorum pterocarpum, the leaves and roots of Impatiens balsamina, and the soils from four sampling sites by instrumental neutron activation analysis. The chondrite normalized rare earth element abundances and distribution patterns in the plant materials were found to be significantly correlated to the abundances of the rare earth elements occurring in the soils. The extent of accumulation of the rare earth elements in some plant materials was also governed by the age of the plants and the plant organs. (author) 16 refs.; 4 figs.; 3 tabs

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Ding Kaihong

    2014-07-01

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

  14. Spatial Bimetallic Castings Manufactured from Iron Alloys

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2007-07-01

    Full Text Available In this paper a conception for manufacturing method of skeleton castings with composite features was shown. Main application of such castings are the working organs of machines subjected to intensive abrasive and erosive wear. Skeleton geometry was based on three-dimensional cubic net consisting of circular connectors and nodes joining 6 connectors according to Cartesian co-ordinate system. Dimension of an elementary cell was equal to 10 mm and diameter of single connector was equal to 5 mm. For bimetallic castings preparation two Fe based alloys were used: L25SHMN cast steel for skeleton substrate and ZlCr15NiMo cast iron for working part of the casting. In presented work obtained structure was analyzed with indication of characteristic regions. Authors described phenomena occurring at the alloys interface and phases in transition zone. A thesis was formulated concerning localization of transition zone at the cast iron matrix – cast steel reinforcement interface. Direction of further studies were indicated.

  15. Rare earth silicide nanowires on silicon surfaces

    International Nuclear Information System (INIS)

    Wanke, Martina

    2008-01-01

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

  16. Rare earth-ruthenium-magnesium intermetallics

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-01

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

  17. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

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

  18. The lattice dynamical studies of rare earth compounds: electron-phonon interactions

    International Nuclear Information System (INIS)

    Jha, Prafulla K.; Sanyal, Sankar P.; Singh, R.K.

    2002-01-01

    During the last two decades chalcogenides and pnictides of rare earth (RE) atoms have drawn considerable attention of the solid state physicists because of their peculiar electronic, magnetic, optical and phonon properties. Some of these compounds e.g. sulphides and selenides of cerium (Ce), samarium (Sm), yttrium (Y), ytterbium (Yb), europium (Eu) and thulium (Tm) and their alloys show nonintegral valence (between 2 and 3), arising due to f-d electron hybridization at ambient temperature and pressure. The rare earth mixed valence compounds (MVC) reviewed in this article crystallize in simple cubic structure. Most of these compounds show the existence of strong electron-phonon coupling at half way to the zone boundary. This fact manifests itself through softening of the longitudinal acoustic mode, negative value of elastic constant C 12 etc. The purpose of this contribution is to review some of the recent activities in the fields of lattice dynamics and allied properties of rare earth compounds. The present article is primarily devoted to review the effect of electron-phonon interactions on the dynamical properties of rare earth compounds by using the lattice dynamical model theories based on charged density deformations and long-range many body forces. While the long range charge transfer effect arises due to f-d hybridization of nearly degenerate 4f-5d bands of rare earth ions, the density deformation comes into the picture of breathing motion of electron shells. These effects of charge transfer and charge density deformation when considered in the lattice dynamical models namely the three body force rigid ion model (TRM) and breathing shell model (BSM) are quite successful in explaining the phonon anomalies in these compounds and undoubtedly unraveled many important physical process governing the phonon anomalies in rare earth compounds

  19. Glass formation ability, structure and magnetocaloric effect of a heavy rare-earth bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jo, C.-L. [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)], E-mail: jochollong@163.com; Xia Lei; Ding Ding; Dong Yuanda; Gracien, Ekoko [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)

    2008-06-30

    The glass formation ability, the structure and the magnetocaloric effect of the bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy were investigated. Bulk metallic glassy (BMGs) alloys were prepared by a copper-mold casting method. The glass forming ability and their structure were studied by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The XRD analysis revealed that the as-cast cylinder of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed fully amorphous structure in 2 mm diameter. The DSC revealed that the bulk cylinder of the Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed a distinct glass transition temperature and a relatively wide supercooled liquid region before crystallization. SQUID investigated the magnetic properties and the entropy changes. The Curie temperature of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} BMGs alloy was about 130 K, but the maximum magnetic entropy changes(-{delta}S{sub M}) showed at about 125 K, a little lower than the Curie temperature 130 K. The reason could probably be due to the presence of a little amount of nanocrystalline particles between amorphous phases. The BMG alloy has the characteristic of second-order transition (SOT) on Arrott plots. The results showed that the amorphous sample had a relatively improved magnetocaloric effect, indicating that the amorphous alloy could be considered as a candidate for magnetic refrigeration applications in the temperature interval range of 100-200 K.

  20. Ion exchange separation of rare earths. I

    International Nuclear Information System (INIS)

    Nghi, Nguyen danh; Matous, K.

    1977-01-01

    The optimal conditions of separating selected rare earths by two ion exchange chromatography using Ostion KS cation exchange resin were studied. The effect of acetic acid concentration in the sorption solution was investigated. The elution process was studied in dependence on the concentration of Na 2 H 2 EDTA, on the total concentration of EDTA 4- ion, on elution agent flow, and on temperature. The optimal conditions were determined by evaluating integral elution curves and changes in acid concentration for systems Y-Pr, La-Pr, Er-Pr, Eu-Pr as follows: The sorption solution requires the presence of Na 2 H 2 EDTA of 0.03M in concentration. The basic elution solution was prepared in the following way: 0.183M Na 2 Mg 2 EDTA, 9.6x10 -3 M Na 2 H 2 EDTA, 3.84x10 -3 M CH 3 COOH, 2.30x10 -2 M CH 3 COONH 4 , 2.30x10 -2 M (NH 4 ) 2 SO 4 . Approximate pH 5.7 to 6.0. The optimal elution solution was prepared by diluting the basic solution so that the total concentration of EDTA 4- equalled 0.075M. The optimal flow was determined to be 0.86 ml.cm -2 .min -1 at a temperature of 55 degC. (author)

  1. Rare-earth-doped fluorozirconate fiber lasers

    International Nuclear Information System (INIS)

    Brierly, M.C.; France, P.W.; Moore, M.W.; Davey, S.T.

    1988-01-01

    Rare-earth-doped fiber lasers fabricated using silica-based fibers are rapidly becoming an established technology. Simultaneously, in the search for lower losses to achieve longer repeaterless communications links, another fiber technology based on fluorozirconate glasses is emerging. Fluorozirconate glass systems are known to be suitable laser hosts, and the authors have already reported Nd-doped fiber lasers using this technology. Recently the authors have used a 0.5-m length of 44-μm core fluorozirconate fiber doped with 1000 ppm of Nd 3+ ions in a longitudinally pumped Fabry-Perot cavity with a 90% output coupler. They observed lasing at 1.05 μm with a threshold of 33-mW launched power at 514 nm and a slope efficiency of 16.8%. The authors attribute this improvement to the higher dopant concentration, better fiber to mirror coupling, and more optimum output coupler reflectivity. In addition the same fiber used with two high-reflector mirrors at 1.35μm produced lasing at 1.35μm with a threshold of 60-mW launched power

  2. Rare Earth Element Phases in Bauxite Residue

    Directory of Open Access Journals (Sweden)

    Johannes Vind

    2018-02-01

    Full Text Available The purpose of present work was to provide mineralogical insight into the rare earth element (REE phases in bauxite residue to improve REE recovering technologies. Experimental work was performed by electron probe microanalysis with energy dispersive as well as wavelength dispersive spectroscopy and transmission electron microscopy. REEs are found as discrete mineral particles in bauxite residue. Their sizes range from <1 μm to about 40 μm. In bauxite residue, the most abundant REE bearing phases are light REE (LREE ferrotitanates that form a solid solution between the phases with major compositions (REE,Ca,Na(Ti,FeO3 and (Ca,Na(Ti,FeO3. These are secondary phases formed during the Bayer process by an in-situ transformation of the precursor bauxite LREE phases. Compared to natural systems, the indicated solid solution resembles loparite-perovskite series. LREE particles often have a calcium ferrotitanate shell surrounding them that probably hinders their solubility. Minor amount of LREE carbonate and phosphate minerals as well as manganese-associated LREE phases are also present in bauxite residue. Heavy REEs occur in the same form as in bauxites, namely as yttrium phosphates. These results show that the Bayer process has an impact on the initial REE mineralogy contained in bauxite. Bauxite residue as well as selected bauxites are potentially good sources of REEs.

  3. Wine Traceability with Rare Earth Elements

    Directory of Open Access Journals (Sweden)

    Maurizio Aceto

    2018-03-01

    Full Text Available The traceability of foodstuffs is now a relevant aspect of the food market. Scientific research has been devoted to addressing this issue by developing analytical protocols in order to find the link between soil and food items. In this view, chemical parameters that can act as soil markers are being sought. In this work, the role of rare earth elements (REEs as geochemical markers in the traceability of red wine is discussed. The REE distribution in samples from each step of the wine making process of Primitivo wine (produced in Southern Italy was determined using the highly sensitive inductively coupled plasma-mass spectrometry (ICP-MS technique. Samples analyzed include grapes, must, and wine samples after every step in the vinification process. The resulting data were compared to the REE distribution in the soil, revealing that the soil fingerprint is maintained in the intermediate products up to and including grape must. Fractionation occurs thereafter as a consequence of further external interventions, which tends to modify the REE profile.

  4. Double Solvent for Extracting Rare Earth Concentrate

    International Nuclear Information System (INIS)

    Bintarti, AN; Bambang EHB

    2007-01-01

    An extraction process to rare earth concentrate which contain elements were yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), gadolinium (Gd) and dysprosium (Dy) which were dissolved in to nitric acid has been done. The experiment of the extraction by double solvent in batch to mix 10 ml of the feed with 10 ml solvent contained the pair of solvent was TBP and TOA, D2EHPA and TOA, TBP and D2EHPA in cyclohexane as tinner. It was selected a right pairs of solvent for doing variation such as the acidity of the feed from 2 - 6 M and the time of stirring from 5 - 25 minutes gave the good relatively extraction condition to Dy element such as using 10 % volume of TOA in D2EHPA and cyclohexane, the acidity of the feed 3 M and the time stirring 15 minutes produced coefficient distribution to dysprosium = 0.586 and separation factor Dy-Ce = ∼ (unlimited); Dy-Nd = 4.651. (author)

  5. Chromatographic Techniques for Rare Earth Elements Analysis

    Science.gov (United States)

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

    2017-04-01

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

  6. HfO2 - rare earth oxide systems in the region with high content of rare earth oxide

    International Nuclear Information System (INIS)

    Shevchenko, A.V.; Lopato, L.M.

    1982-01-01

    Using the methods of annealing and hardenings (10 2 -10 4 deg/s cooling rate) and differential thermal analysis elements of state diagrams of HfO 2 - rare earth oxide (rare earths-La, Pr, Nd, Sm, Gd, Tb, Dy, Y, Er, Yb, Lu, Sc) systems from 1800 deg C up to melting in the range of 60-100 mol% rare earth oxide concentration were constructed. Regularities of HfQ 2 addition effect on high-temperature polymorphic transformations of rare earth oxides were studied. Results of investigation were discussed from viewpoint of crystal chemistry

  7. Magnetic strength and corrosion of rare earth magnets.

    Science.gov (United States)

    Ahmad, Khalid A; Drummond, James L; Graber, Thomas; BeGole, Ellen

    2006-09-01

    Rare earth magnets have been used in orthodontics, but their corrosion tendency in the oral cavity limits long-term clinical application. The aim of this project was to evaluate several; magnet coatings and their effects on magnetic flux density. A total of 60 neodymium-iron-boron magnets divided into 6 equal groups--polytetrafluoroethylene-coated (PTFE), parylene-coated, and noncoated--were subjected to 4 weeks of aging in saline solution, ball milling, and corrosion testing. A significant decrease in magnet flux density was recorded after applying a protective layer of parylene, whereas a slight decrease was found after applying a protective layer of PTFE. After 4 weeks of aging, the coated magnets were superior to the noncoated magnets in retaining magnetism. The corrosion-behavior test showed no significant difference between the 2 types of coated magnets, and considerable amounts of iron-leached ions were seen in all groups. Throughout the processes of coating, soaking, ball milling, and corrosion testing, PTFE was a better coating material than parylene for preserving magnet flux density. However, corrosion testing showed significant metal leaching in all groups.

  8. Unraveling Recrystallization Mechanisms Governing Texture Development from Rare Earth Element Additions to Magnesium

    Science.gov (United States)

    Imandoust, Aidin

    The origin of texture components associated with rare-earth (RE) element additions in wrought magnesium (Mg) alloys is a long-standing problem in magnesium technology. The objective of this research is to identify the mechanisms accountable for rare-earth texture during dynamic recrystallization (DRX). Towards this end, we designed binary Mg-Cerium and Mg-Gadolinium alloys along with complex alloy compositions containing zinc, yttrium and Mischmetal. Binary alloys along with pure Mg were designed to individually investigate their effects on texture evolutions, while complex compositions are designed to develop randomized texture, and be used in automotive and aerospace applications. We selected indirect extrusion to thermo-mechanically process our materials. Different extrusion ratios and speeds were designed to produce partially and fully recrystallized microstructures, allowing us to analyze DRX from its early stages to completion. X-ray diffraction, electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to conduct microstructure and texture analyses. Our analyses revealed that rare-earth elements in zinc-containing magnesium alloys promote discontinuous dynamic recrystallization at the grain boundaries. During nucleation, the effect of rare earth elements on orientation selection was explained by the concomitant actions of multiple Taylor axes in the same grain. Isotropic grain growth was observed due to rare earth elements segregating to grain boundaries, which lead to texture randomization. The nucleation in binary Mg-RE alloys took place by continuous formation of necklace structures. Stochastic relaxation of basal and non-basal dislocations into low-angle grain boundaries produced chains of embryos with nearly random orientations. Schmid factor analysis showed a lower net activation of dislocations in RE textured grains compared to ones on the other side of the stereographic triangle. Lower dislocation densities within

  9. Preparation and characterization of PT-rare earth/C electrocatalysts for PEM fuel cells

    International Nuclear Information System (INIS)

    Santoro, Thais Aranha de Barros

    2009-01-01

    Pt-rare earth/C electrocatalysts (rare earth = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, and Lu) were prepared (20 wt.% and Pt-to-RE atomic ratio of 50:50) by an alcohol reduction process using H 2 PtCl 6 .6H 2 O (Aldrich) and rare earth (III) chlorides (Aldrich) as metal sources, ethylene glycol as solvent and reducing agent, and Vulcan XC72 as support. The electrocatalysts were characterized by Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The energy dispersive x-ray spectroscopy analysis showed that the Pt-Rare Earth atomic ratios obtained for all electrocatalysts were similar to those used in the preparations. In all diffractograms, it was observed a broad peak at about 25 degree which was associated to the Vulcan XC72 support material and four peaks at approximately 28=40 degree, 47 degree, 67 degree and 82 degree, which were associated to the (111), (200), (220), (311), and (222) planes, respectively, of the face-centered cubic (fcc) structure characteristic of platinum and platinum alloys. For the Pt-Rare Earth/C electrocatalysts, it was also observed peaks related to the rare earth oxides on the X ray diffractograms. PtLa/C electrocatalysts were prepared at different atomic ratio. Transmission electronic microscopy micrographs of electrocatalysts showed a reasonable distribution of the Pt particles on the carbon support with some agglomerations, which is in agreement with x-ray diffractometry result. The performance for CO, methanol and ethanol oxidation was investigated by cyclic voltammetry, chronoamperometry and Fourier transform infrared spectroscopy spectroscopy. The electrocatalytic activity of the Pt-Rare Earth/C electro catalyst, specially PtLa/C, were higher than that of the Pt/C electrocatalyst. Fourier transform infrared spectroscopy studies for ethanol oxidation on Pt-Rare Earth/C electrocatalyst showed that acetaldehyde and acetic acid were the main products. The PtLa/C (30

  10. Study of the pyrophoric characteristics of uranium-iron alloys

    International Nuclear Information System (INIS)

    Duplessis, X.

    2000-01-01

    The objective of the study is to understand the pyrophoric characteristics of uranium-iron alloys. In order to carry out this research we have elected to use uranium-iron alloy powder with granules of 200 μm and 1000 μm diameter with 4%, 10.8% and 14% iron content. The experiments were performed on small samples of few milligrams and on larger quantities of few hundred grams. The main conclusions obtained are the followings: -The reaction start at 453 K (180 deg. C) and the ignition at 543 K (270 deg. C) - The influence of the specific area seems more important than the iron concentration in the alloys - When the alloy ignites, the fire spreads quickly and the alloy rapidly consumes. (author)

  11. Magnetostriction of rare earth-Fe2 Laves phase compounds

    International Nuclear Information System (INIS)

    Clark, A.E.; Abbundi, R.; Savage, H.T.

    1977-01-01

    Single crystal magnetostriction measurements were made as a function of temperature on TbFe 2 and DyFe 2 . From these, the intrinsic magnetoelastic coupling coefficients were determined for the rare earth-Fe 2 compounds. Employing X-ray techniques, certain multicomponent rare earth-Fe 2 compounds were identified to maximize the magnetostriction to anisotropy ratio. (Auth.)

  12. Preparation, thermogravimetric study and infrared spectra of rare earth acetates

    International Nuclear Information System (INIS)

    Graehlert, X.; Starke, M.

    1992-01-01

    The anhydrous and the hydrated acetates of Ho, Er, Tm, Yb and Lu have been prepared. The compounds obtained have been investigated by thermogravimetric analysis and infrared spectroscopy. The thermal decomposition of the rare earth acetates may proceed via various steps. It depends on both the number of crystal water molecules in the acetates and the rare earth element's behaviour. (orig.)

  13. Advances in chromatography of the rare earth elements (review)

    International Nuclear Information System (INIS)

    Oguma, Koichi; Kuroda, Rokuro; Shimizu, Tsuneo.

    1995-01-01

    A review is presented which covers liquid chromatography, gas chromatography, and related techniques. This article intends to describe the chromatographic methods playing an important role in the separation of the rare earth elements. Special attention is paid to the usefulness of various types of liquid chromatography which enable the complete mutual separation of the rare earth elements. Applications are also discussed. (author) 161 refs

  14. Separation of rare earths from solutions of phosphoric acid

    International Nuclear Information System (INIS)

    Jones, E.A.

    1977-01-01

    Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

  15. Rare earth silicide nanowires on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina

    2008-11-10

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

  16. Production technique of vermicular graphite iron cylinder head of vehicle diesel engine

    Directory of Open Access Journals (Sweden)

    Zhou Gen

    2008-11-01

    Full Text Available The 25 years’production and application have proved that vermicular graphite iron cylinder heads with vermicularity ≥50% satisfy the machinability and performance demand of diesel engine. The method, in which using cupola-induction furnace duplex melting and pour-over process with rare earth-ferrosilicon or rare earthsilicon compound as vermicularizing alloy plus rare earth-magnesium-ferrosilicon as stirring alloy, is an optimal vermicularizing process for obtaining satisfi ed vermicularity. Using top kiss risers, enlarging kissing areas and expanding covering width and making ingates to freeze earlier are the effective measures to eliminate shrinkage, blowhole and oxide inclusions in the vermicular graphite iron cylinder heads.

  17. Kinetics studies of solvent extraction of rare earths into DEHPA

    International Nuclear Information System (INIS)

    Lim, T.M.; Tran, T.

    1996-01-01

    The kinetics of rare earth solvent extraction into di(2-ethylhexyl) phosphoric acid have been studied using radiotracers ( 141 Ce, 152 Eu, 153 Gd, 160 Tb and 88 Y) in a modified Lewis cell. The experimental procedure involved continuous monitoring of both aqueous and organic phases using an automated γ- counting system. Using this method, highly reproducible results were obtained without chemical analysis or disturbance of the system. The initial rate extraction was first order with respect to individual rare earth concentration. At low acidities ([H+] < 0.01 M), the extraction rates of rare earths were equal and independent of pH. However, at high acidities, the extraction rate was strongly dependent on pH and varied between the rare earths. Similarly, differences in the extraction rate of individual rare earths were apparent at low DEHPA concentration. (authors)

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

    Science.gov (United States)

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

    1963-02-26

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

  19. Determination of active oxygen content in rare earth peroxides

    International Nuclear Information System (INIS)

    Queiroz, Carlos A.S.; Abrao, Alcidio

    1993-01-01

    The content of active oxygen in rare earth peroxides have been determined after the dissolution of the samples with hydrocloridic acid in the presence of potassium iodide. The free generated iodine is titrated with sodium thiosulfate using starch as indicator. The oxidation of iodide to the free iodine indicates the presence of a higher valence state rare earth oxide, until now specifically recognized for the oxides of cerium (Ce O 2 ), praseodymium (Pr 6 O 1 1) and terbium (TB 4 O 7 ). recently the authors synthesized a new series of rare earth compounds, the peroxides. These new compounds were prepared by precipitating the rare earth elements complexed with carbonate ion by addition of hydrogen peroxide. the authors demonstrated that all rare earth elements, once solubilized by complexing with carbonate ion, are quantitatively precipitated as peroxide by addition of hydrogen peroxide. (author)

  20. Effect of diluted alloying elements on mechanical properties of iron

    International Nuclear Information System (INIS)

    Hassan, A.A.S.

    1996-01-01

    Iron and its alloys have extensive applications. The effect of solute additions on mechanical properties of iron was investigated to check the efficiency of solute atoms on strength and surface e life. Additions in the range of 0.1 wt.% and 0.3 wt.% of alloying elements of Cu,Ni and Si were used. Samples of grains size ranged from 6-40 m which have been prepared by annealing followed by furnace cooling. The recrystallization temperature increases with alloying addition (475 degree C for Fe-0.3 wt. % C alloy compared to 375 degree C for pure iron). Si and Cu additions inhibit grain growth of iron whereas Ni addition enhances it.Addition of Si or Ni to iron induced softening below room temperature whereas addition of Cu caused hardening. The work hardening parameters decreased due to alloying additions. The strength coefficient K was 290 M N/m2 for Fe-03 wt % Ni compared to 340 M N/m2 for pure iron. The work hardening exponent n is 0.12 for fe-0.3 wt. Cu alloy compared to 0.17 for pure iron. All the investigated alloys fulfilled the Hall-Petch relation at liquid Nitrogen and at room temperature. Alloying addition which caused softening addition which caused hardening increased the Half-Petch parameters. Ni addition favors ductility of iron whereas Cu addition reduces it. Alloying additions generally lead to brittle fracture and decrease the crack resistance of iron. 9 tabs., 55 figs., 103 refs

  1. Magnetic form factors of rare earth ions

    International Nuclear Information System (INIS)

    Deckman, H.W.

    1976-01-01

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

  2. Radiological aspects in a monazite based rare earth production facility

    International Nuclear Information System (INIS)

    Harikumar, M.; Sujata, R.; Chinnaesakki, S.; Tripathi, R.M.; Puranik, V.D.; Nair, N.N.G.

    2011-01-01

    One of the largest reserves of monazite in the world is present in the Indian subcontinent. Monazite ore has around 8-9% thorium oxide and nearly 60% Rare earth oxides. Selective acid extraction is used to separate the composite rare earths. The main radiological hazard arises from the presence of thorium and its daughter products. Monitoring of the radiation field and air activity in the rare earths plant is done routinely to reduce the radiation exposure to plant personnel. The separation of uranium and rare earths from Thorium concentrate separated from Monazite is being done as a part of the THRUST (Thorium Retrieval, Recovery of Uranium and Re-storage of Thorium) project from 2004 at Indian Rare Earths Limited, Udyogamandal. The radiological aspect for this extraction of uranium and rare earths was studied. The general radiation field in the rare earth production plant was 0.3-5.0 μGyh -1 and the average short lived air activity was 46 ± 7 mWL. The long lived air activity arising from 232 Th is very insignificant radiologically. The occupational radiation exposure for the rare earths separation plant is only 6 % of the total dose and the estimated average individual dose is 1.6 mSv per year. Studies were also done to estimate the residual radioactivity in the separated rare earth compounds using gamma spectrometry and the results showed significant presence of 227 Ac arising due to the protactinium fraction in the thorium concentrate. This activity is not detectable in a freshly separated rare earth compound but can buildup with time. (author)

  3. Simultaneous gettering of oxygen and chlorine and homogenization of the β phase by rare earth hydride additions to a powder metallurgy Ti–2.25Mo–1.5Fe alloy

    International Nuclear Information System (INIS)

    Yan, M.; Liu, Y.; Liu, Y.B.; Kong, C.; Schaffer, G.B.; Qian, M.

    2012-01-01

    A detailed transmission electron microscopy analysis has revealed that small additions of yttrium hydride to a powder metallurgy Ti–2.25Mo–1.5Fe alloy resulted in the formation of both chlorine-free yttrium oxides and essentially oxygen-free yttrium chlorides. The oxides and chlorides showed distinctly different morphologies and spatial distribution. Yttrium acted as a potent getter for both oxygen and chlorine. Additionally, the β-Ti phase was free of nanoscaled α-Ti in the presence of yttrium. These microstructural changes contribute to the substantially increased ductility (∼90%).

  4. Bioleaching of rare earth elements from monazite sand.

    Science.gov (United States)

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

    2016-02-01

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

  5. Sc, Y, La-Lu - Rare Earth Elements

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    At present extensive efforts are being made in completing work on system number Rare Earth Elements. Part A is devoted to the occurrence of these elements on the earth and in the universe. Part B deals with the pure metals; the 7 volumes published cover the description of the separation from the raw materials, the preparation of pure metals,their uses and toxicology, the physical properties of nuclei, atoms, molecules, and isotopes; in addition the behavior of ions in solution and the electrochemical behavior of rare earth elements are described. The compounds are described in Part C. Part D with 6 volumes has been devoted to the description of coordination compounds and is completed. The volume ''Rare Earth Elements C 10'' deals with the rare earth tellurides, oxide tellurides, tellurates, telluride halides, tellurate halides, sulfide tellurides, selenide tellurides, and alkali rare earth tellurates. Another topic of this volume are the compounds of the rare earth elements with polonium. So far as meaningful and in accordance with all earlier volumes of ''Rare Earth Elements'' Series C, comparative data are presented in sections preceding treatment of the individual compounds and systems

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

    Science.gov (United States)

    Pourret, Olivier; Tuduri, Johann

    2017-07-19

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

  7. Elimination of Iron Based Particles in Al-Si Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2015-03-01

    Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.

  8. The recovery of rare earth elements (REE) from beach sands

    International Nuclear Information System (INIS)

    Petrache, Cristina A.; Santos, Gabriel P. Jr.; Fernandez, Lourdes G.; Castillo, Marilyn K.; Tabora, Estrellita U; Intoy, Socorro P.; Reyes, Rolando Y.

    2005-01-01

    This preliminary study describes a metallurgical process that will extract, recover and produce REE oxides from beach sands obtained from Ombo, San Vicente, northern Palawan. The beach sands contain REE minerals of allanite and small amounts of monazite. Allanite is a sorosilicate mineral containing rare earths, thorium and uranium. Monazite is the anhydrous phosphate of cerium and the lanthanum group of rare earths with thorium commonly present in replacement for cerium and lanthanum. Collected beach sand were first pan-concentrated in-situ to produce heavy mineral concentrates. Screening using a 32 mesh (0.500 mm) sieve was done at the Nuclear Materials Research Laboratory to remove oversize sand particles. The -32 mesh fraction was treated with bromoform (sp. gr. 2.89) to separate the heavy minerals from siliceous gangue. Grinding to -325 mesh size (0.044mm) followed to liberate the minerals prior to leaching. Two acids leachants were used - concentrated HCl for the first trial and a mixture of concentrated HCl and HNO 3 (10:1 volume ratio) for the second trial. Both leaching trials were carried out at 180 o C for 7 hours or until dry. The resulting leached residues were re-dissolved in concentrated HCl and filtered. Ionquest R 801, an organophosphorous extractant, was added to the filtrate to separate the radioactive thorium from REE. Sodium hydroxide was added to the aqueous phase to precipitate the REE. After filtering the precipitate, it was dissolved in HCl. The acid solution was repeatedly extracted three (3) times with Ionquest R 801 to remove iron and other contaminants. Ammonium hydroxide was added to the final solution to precipitate the REE, which was then dried in the oven. The precipitate was calcined/roasted in the furnace at two different temperatures for different periods of time to burn off the organic matter and to form oxides. Results of the XRD analysis showed peaks of the calcined precipitate matching with the peaks of lanthanum oxide

  9. Raw materials for advanced ceramics: rare earths separation processes

    International Nuclear Information System (INIS)

    Ricci, D.R.; Nobre, J.S.M.; Paschoal, J.O.A.

    1990-01-01

    The importance of obtaining purified rare earths oxidesis related, mainly to the increasing use of these compounds as raw materials for advanced ceramics. Processes of rare earths separation and purification are almost always based on the solvent extraction, fractional precipitation and ion exchange chromatography techniques, whose association depends on the initial concentrate and on the desired purity. This paper describes some steps of fractionation of didymium carbonate by using the solvent extraction and fractional precipitation techniques. The experimental conditions presented here have enable the production of lantanium, neodimium - praseodimium, samarium - gadolinium and ytrium concentrates, which constitute the intermediate fractions of the overall process to obtain high purity rare earths. (author) [pt

  10. Forced-flow chromatography of rare earths using sensitive spectrophometry

    International Nuclear Information System (INIS)

    Matsui, Masakazu; Aoki, Toru; Kumagai, Tetsu.

    1981-01-01

    The sensitive spectrophotometric method for the rare earth elements with xylenol orange in the presence of cetylpyridinium bromide was applied to the continuous detection system of liquid chromatography. Fourteen rare earth elements were completely separated within 130 min cation-exchange chromatography using 2-hydroxy-iso-butylic acid. The eluted ions were determined with absorption maxima of their complexes at around 610 nm. A linear relationship between the peak height and the amounts of rare earth elements was also obtained over the range 0.04 to 0.5 MU g. (author)

  11. Thermal Oxidation Resistance of Rare Earth-Containing Composite Elastomer

    Institute of Scientific and Technical Information of China (English)

    邱关明; 张明; 周兰香; 中北里志; 井上真一; 冈本弘

    2001-01-01

    The rare earth-containing composite elastomer was obtained by the reaction of vinyl pyridine-SBR (PSBR) latex with rare earth alkoxides, and its thermal oxidation resistance was studied. After aging test, it is found that its retention rate of mechanical properties is far higher than that of the control sample. The results of thermogravimetric analysis show that its thermal-decomposing temperature rises largely. The analysis of oxidation mechanisms indicates that the main reasons for thermal oxidation resistance are that rare earth elements are of the utility to discontinue autoxidation chain reaction and that the formed complex structure has steric hindrance effect on oxidation.

  12. Thermochemistry of certain rare earth and ammonium double chlorides

    International Nuclear Information System (INIS)

    Usubaliev, D.U.; Abramtsev, V.A.; Kydynov, M.K.; Vilyaev, A.N.

    1987-01-01

    In a calorimeter with isothermal casing at 25 deg C dissolution enthalpies of double chlorides of rare earths and ammonium LnCl 3 x2NH 4 Cl (Ln=La, Sm) and LnCl 3 x3NH 4 Cl (Ln=Gd, Tb, Ho) in water, as well as dissolution enthalpy of rare earth chlorides in solution of ammonium chloride and NH 4 Cl in solution of rare earth chloride, have been measured. Formation enthalpies, standard formation enthalpies, dissociation enthalpies of the above-mentioned double chlorides are calculated

  13. Membrane assisted solvent extraction for rare earth element recovery

    Science.gov (United States)

    Bhave, Ramesh R.; Kim, Daejin; Peterson, Eric S.

    2018-05-15

    Systems and methods for the recovery of rare earth elements are provided. The systems and methods generally include membrane assisted solvent extraction using permeable hollow fibers having an immobilized organic phase within the pores of the hollow fibers. The permeable hollow fibers are generally in contact with an acidic aqueous feed on one side thereof and a strip solution on another side thereof. The systems and methods generally include the simultaneous extraction and stripping of rare earth elements as a continuous recovery process that is well suited for post-consumer products, end-of-life products, and other recovery sources of rare earth elements.

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

    Science.gov (United States)

    Chemin, Marie-Charlotte

    2015-04-01

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

  15. Effect of iron and silicon in aluminium and its alloys

    International Nuclear Information System (INIS)

    Kovacs, I.

    1990-01-01

    The iron and silicon are the main impurities in aluminium, they are always present in alloys made from commercially pure base material. The solid solubility of iron in aluminium is very low, therefore its largest amount forms intermetallic compounds the kind of which depends strongly on the other impurities of alloying elements. Although the solid solubility of silicon is much larger than that of the iron, it is the constituent of both the primary and the secondary particles, the structure of which depends in general on the iron-silicon concentration ratio. These Fe and Si containing particles can cause various and basic changes in the macroscopic properties of the alloy. Since commercially pure aluminium has extensive consumer and industrial use, it is very important to know, not only from scientific but also from practical point of view, the effect of iron and silicon on the physical and mechanical properties of aluminium and its alloys. The aim of the ''International Workshop on the Effect of Iron and Silicon in Aluminium and its Alloys'' was to clarify the present knowledge on this subject. The thirty papers presented at the Workshop and collected in this Proceedings cover many important fields of the subject. I hope that they will contribute to both the deeper understanding of the related phenomena and the improvement of technologies for producing better aluminium alloys

  16. Study of treatment of a thorium and rare earths residue by extraction chromatography

    International Nuclear Information System (INIS)

    Zini, Josiane; Abrao, Alcidio; Carvalho, Fatima Maria Sequeira de; Freitas, Antonio Alves de; Scapin, Marcos Antonio

    2005-01-01

    In the 70's was established at IPEN the project of a thorium compounds purification pilot plant that had the goal of fulfilling the nuclear technology purity standards. The used method was the purification by extraction with solvents in pulsed columns. The thorium remaining in the organic phase was back extracted as thorium nitrate with a high degree of purity. Impurities, thorium non-extracted and practically all rare earths in aqueous phase of this chemical process were precipitated as hydroxide, generating a product containing thorium and rare earths, that was denominated RETOTER (residue of thorium and rare earths). This residue was accumulated and today there are 25 (twenty-five) metric tons of this by product stored in the safeguard storage shed at IPEN that must to be treated due to the radiation of the thorium and mainly his daughters. The average composition of this residue is, 68% in thorium oxide (ThO 2 ), 5% in rare earths oxides (R 2 O 3 ), 0,3% in uranium oxide (U 3 O 8 ) and common impurities such as phosphorus, iron, titanium, lead and sodium. In this work a new method is presented for separation and purification of thorium from this residue, obtaining a concentrate with high degree of purity for nuclear and non-nuclear use. This process will contribute to establish a decreasing of residue volumes, to have a mind to the minimization of environmental impacts, the reduction of worker's exposition and reduction of the storage costs. In this process the separation and purification of uranium and thorium is done by chromatography extraction, being used polymeric resins, that are previously functionalized with organic solvent (extractor agent). The effluent of this process is a concentrate of rare earths that can be reprocessed in a subsequent fractionating for to obtaining the individual fractions. (author)

  17. Textural and morphological studies on zinc-iron alloy electrodeposits

    Indian Academy of Sciences (India)

    Zinc-iron alloy electrodeposits have industrial significance, since they provide better corrosion resistance and with improved mechanical properties when compared to pure zinc coatings. This is due to the unique phase structure of the alloy formed. But this deposition belongs to anomalous deposition, where the ...

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

    Science.gov (United States)

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

    2014-01-01

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

  19. The electrodeposition and rare earths reduction in the molten salt actinides recovery systems using liquid metal

    International Nuclear Information System (INIS)

    Shim, J-B.; Lee, J-H.; Kwon, S-W.; Ahn, B-G.; Woo, M-S.; Lee, B-J.; Kim, E-H.; Park, H-S.; Yoo, J-H.

    2005-01-01

    A pyrochemical partitioning system uses liquid metals such as cadmium and bismuth in order to recover the actinide metals from a molten salt mixture containing rare earth fission product metals. The liquid metals play roles as a cathode in the electrowinning or an extracting phase in the reductive extraction operation. The product resulting from the above operations is metal-cadmium or-bismuth alloy, which should contain the rare earth element amounts as low as possible for a transmutation purpose. In this study, the electrodeposition behaviours of uranium and lanthanide elements such as La, Ce and Nd were investigated for solid molybdenum and liquid cadmium electrodes in a molten LiCl-KCl eutectic salt. Electrochemical methods used are a cyclic voltammetry (CV) and a chronopotentiometry for monitoring the salt phase and recovering the metals, respectively. The CV graphs for monitoring the oxidizing agent CdCl 2 in the salt phase were obtained. These show a time dependently disappearance of the oxidizing agent corresponding to the formation of UCl 3 by inserting the uranium metal into the salt. Also, a sequential oxidation technique which is added at a controlled amount of the oxidizing agents into the salt phase was applied. It was found that this method is feasible for the selective reduction of the rare earths content in liquid metal alloys. (author)

  20. Study on lowering the specific radioactivity of rare earth chlorides

    International Nuclear Information System (INIS)

    Shinhuor, Y.; Jyuung, J.; Shyuerjung, T.; Xiangping, L.

    1985-01-01

    In this paper, the source of radioactivity in rare earth chlorides and the chemical behaviour of its main radionuclides in metallurgy processing are investigated. It is pointed out that the radioactivity in rare earths comes from the long-life radionuclides in three natural radioactive series. Nine of them (/sup 238/U, /sup 234/U, /sup 230/Th, /sup 226/Ra, /sup 210/Po, /sup 232/Th, /sup 228/Th, /sup 235/U, /sup 231/Pa) are alpha-emitters, three of them (/sup 228/Ra, /sup 227/Ac, /sup 210/Pb) are beta-emitters. Among them alpha-emitters contribute the total specific activity of rare earths directly. The rare earths are easily purified in preferential dissolution, radium elimination, and other processes

  1. Separation of heavier rare earths from neutron irradiated uranium targets

    International Nuclear Information System (INIS)

    Bhargava, V.K.; Rao, V.K.; Marathe, S.G.; Sahakundu, S.M.; Iyer, R.H.

    1978-01-01

    A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly suitable for the separation of low yield (10sup(-5)%-10sup(-7)%), highly asymmetric rare earth fission products viz. sup(179,177)Lu, sup(175)Yb, sup(173)Tm, sup(172,171)Er, sup(167)Ho and sup(161,160)Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated for decontamination from sup(239)Np (an activation product) and sup(93-90)Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths is achieved by a cation exchange method performed at 80 deg C by elution with α-hydroxyisobutyric acid (α-HIBA). (author)

  2. Separation of rare earths by liquid-liquid extraction

    International Nuclear Information System (INIS)

    Helgorsky, M.; Leveque, M.

    1978-01-01

    The elements of the rare earth family are characterised by very similar chemical properties connected with their special electronic structure. The purification of the rare earths sold by RHONE-POULENC is now done by the liquid-liquid extraction technique. The development of different extracting agents and also counter-current techniques have led to solvent extraction replacing the other fractionation techniques because of its efficiency and low cost. There are usually several possible solutions to the main problem of choosing the extracting agent and its mode of use. The difficulty is to find the most economical one taking account of the thermodynamic and hydrodynamic constraints of the solvent. It is shown how ideas about the separation have changed over the course of the development of the uses of the rare earths, ending finally in an integrated scheme that makes RHONE-POULENC a world leader of manufacturers of separated rare earths [fr

  3. Exploitation of rare earth catalysts in polymer syntheses

    Institute of Scientific and Technical Information of China (English)

    Shen Zhiquan

    2006-01-01

    The studies over forty years on rare earth catalysts in polymer syntheses of diene,alkyne,alkylene oxide,thiirane, carbon dioxide copolymerization, lactide,caprolactone,cyclic carbonate and so forth in China have been reviewed.

  4. Prospects for trivalent rare earth molecular vapor lasers for fusion

    International Nuclear Information System (INIS)

    Krupke, W.F.

    1976-01-01

    The dynamical properties of three types of RE 3+ molecular vapors were considered: (1) rare earth trihalogens, (2) rare earth trihalogens complexed with transition metal trihalogens, and (3) rare earth chelates. Radiative and nonradiative (unimolecular and bimolecular) transition probabilities have been calculated using phenomenological models predicted on the unique electronic structure of the triply ionized RE ion (well shielded ground electronic configuration of equivalent of electrons). Although all the lanthanide ions have been treated in some detail, specific results are presented for the Nd 3+ and Tb 3+ ions to illustrate the systematics of these vapors as a class of new laser media. Once verified, these phenomenological models will provide a powerful tool for the directed experimental exploration of these systems. Because of the structural similarity to the triply ionized actinides, comments offered here for the lanthanide rare earth series generally apply to gaseous actinide lasers which are also under consideration

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

    Science.gov (United States)

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

    2016-01-01

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

  6. Flotation process of lead-, copper-, uranium-, and rare earth minerals

    International Nuclear Information System (INIS)

    Broman, P.G.; Kihlstedt, P.G.; Du Rietz, C.

    1977-01-01

    This invention relates to a flotation process of oxide or sulfide ores containing lead-, copper-, uranium-, and rare earth minerals applicating a new collector. Flotation is in the presence of a tertiary amine

  7. Science and technology of the rare earth elements

    International Nuclear Information System (INIS)

    Azzouz, Abdelkrim; Chegrouche, Salah; Telmoune, Sid-Ali; Layachi, Lazhar

    1992-07-01

    The present work studies the chemical physics properties, the different methods of analysis (neutron activation, emission spectrometry, chromatography), and the techniques of separation of rare earth (electrodeposition, thermic decomposition, salts distillation and ions exchange)

  8. Isomerization of butene-1 on rare earth oxides. [Rare earths: La, Nd, Dy

    Energy Technology Data Exchange (ETDEWEB)

    Khodakov, Yu S; Nesterov, V K; Minachev, Kh M [AN SSSR, Moscow. Inst. Organicheskoj Khimii

    1975-09-01

    A study has been made into the isomerization of butene-1 on oxides of rare-earth elements. The dependence of the reaction rate at 20/sup 0/C on the baking temperature of La and Nd oxides have the maximum at 700/sup 0/C. A decrease in the activity of these oxides after bakinq at 800/sup 0/C is observed, as well as during experiments at -30 deq C. In the case of Dy/sub 2/O/sub 3/, the activity at 20/sup 0/C increases gradually with Tsub(bak)=500 to 800/sup 0/C Zeolite 0.57LaNaY exhibits maximum activity at Tsub(bak)=500/sup 0/C Similar data as to the effect of the baking temperature on the catalyst activity were obtained earlier for hydrogenation of ethylene. According to their maximum activity, oxides of rare-earth elements, in the isomerization as well as hydrogenation reactions, can be arranged as follows: La/sub 2/O/sub 3/>Nd/sub 2/O/sub 3/

  9. Magnetism in rare-earth metals and rare-earth intermetallic compounds

    International Nuclear Information System (INIS)

    Johansson, B.; Nordstroem, L.; Eriksson, O.; Brooks, M.S.S.

    1991-01-01

    Some of out recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, R m M n , is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe 2 and RFe 2 (R=Gd-Yb) systems are presented, where a method to treat simultaneously the localized 4f and the conduction electron spin magnetism is introduced. Thereby it becomes possible to calculate the K RM exchange coupling constant. This method is also used to study theoretically the permanent magnet material Nd 2 Fe 14 B. The electronic structure of the anomalous ferromagnets CeFe 2 and CeCo 5 is discussed and an induced 4f itinerant magnetism is predicted. The γ-α transition in cerium metal is considered, and results from calculations including orbital polarization are presented, where a volume collapse of 10% is obtained. On one side of the transition the 4f electrons are calculated to be essentially non-bonding (localized) and on the other side they are found to contribute to the metallic bonding and this difference in behaviour gives rise to the volume collapse. Recent calculations by Wills, Eriksson and Boring for the crystal structure changes in cerium metal under high pressure are discussed. Their successful results imply an itinerant picture for the 4f electrons in α-cerium. Consequently this strongly supports the view that the γ-α phase transformation is caused by a Mott transition of the 4f electrons. (orig.)

  10. Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

    International Nuclear Information System (INIS)

    Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

    1978-01-01

    Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)

  11. Moessbauer spectroscopy of 151Eu and 153Eu. Applications to structural chemistry and electronic properties of rare-earth compounds

    International Nuclear Information System (INIS)

    Meyer, Marc.

    1975-01-01

    The decrease of the 151 Eu isomer shift on hydrogenation of a dilute EuPd alloy (2.5at% Eu) is discussed in term of the volume effect on the charge density at the nucleus. It is shown from 153 Eu Moessbauer spectroscopy in rare earth titanates that a vibrational anisotropy lead to the observation of a Goldanskii-Karyagin effect [fr

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

    Science.gov (United States)

    2013-11-01

    to exert their monopolistic control of the market by artificially restricting supply in the interest of higher commodity prices, but were rather...linked. World markets for rare earth elements are at present a near-monopoly controlled by China, and it is becoming ever clearer that alternative... markets for rare earth elements are at present a near- monopoly controlled by China, and it is becoming ever clearer that alternative sources for these

  13. Rare-earth elements in granites: concentration and distribution pattern

    International Nuclear Information System (INIS)

    Galindo, A.C.

    1983-01-01

    The geochemistry of rare earth elements in granites is studied. The rare earth element (REE) distribution pattern in granites is characterized by a smooth curve with decreasing concentrations from La to Lu, and frequently a marked Eu negative anomaly. It seems to exist relationship between granite genesis and its REE pattern, in that bodies of primary (magmatic differentiation) origin always show this negative Eu anomaly, while those bodies generated by crustal anatexis do not show this anomaly. (E.G.) [pt

  14. Synthesis and physicochemical investigation of adducts of rare earth thenoyltrifluoroacetonates

    International Nuclear Information System (INIS)

    Anufrieva, S.I.; Snezhko, N.I.; Martynenko, L.I.; Pechurova, N.I.

    1982-01-01

    Adducts of rare earth thenoyltrifluoroacetonates (3) have been synthesized with tributylphosphate (TBP), trioctylphosphenoxide (TOPO), triphenylphosphenoxide (TPO) of 1:1 and 1:2 composition as well as with α, α'-dipyridine (Dipy), o-phenanthroline (Phen) of 1:1 composition. The separated adducts have been studied by methods of element analysis, X-ray phase and derivatographic analyses and IR spectroscopy. It is shown that the adducts are more thermostable compared to the corresponding rare earth thenoyltrifluoroacetonate hydrates

  15. Chromates (3) and chromates (5) of rare earths

    International Nuclear Information System (INIS)

    Suponitskij, Yu.L.

    1986-01-01

    Data on preparation methods, structure and properties of chromates (3, 5) and mixed chromates (3) of rare earths, scandium and yttrium are generalized. Phase diagrams of systems Ln 2 O 3 -Cr 2 O 3 (Ln - rare earths, Sc, Y), chemical and thermodynamic properties of chromates (3, 5), their crystal structure and character of thermal decomposition are considered. Application fields of the compounds mentioned are suggested

  16. Yttrium and rare earths separation by ion exchange resin

    International Nuclear Information System (INIS)

    Pinatti, D.G.; Ayres, M.J.G.; Ribeiro, S.; Silva, G.L.J.P.; Silva, M.L.C.P.; Martins, A.H.

    1988-01-01

    The experimental results of yttrium and rare earths separation from Brazilian xenotime are presented. The research consist in five stage: 1) Preparation of yttrium, erbium and lutetium standard solutions, from solubilization of pure oxides 2) yttrium and rare earths separation by ion exchange chromatrography 3) Separation and recovery of EDTA 4) Precipitation and calcination and 4) Analytical control of process. (C.G.C.) [pt

  17. Rare Earth-Activated Silica-Based Nanocomposites

    Directory of Open Access Journals (Sweden)

    C. Armellini

    2007-01-01

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

  18. Determination of rare earths in their extraction processing

    International Nuclear Information System (INIS)

    You Jiannan; Zhang Yuqin

    1989-01-01

    A method for determination of rare earths in ores, ion-exchange resins and solution samples has been developed. The ore is molten with sodium peroxide and the molten sample is leached with triethenol amine and sodium citrate. In weak acid medium, the rare earths can be extracted by PMBP-phenol solution, and stripped with formic acid. In the acetic acidsodium acetate buffer medium of pH3, the spectrophotometric determination of rare earths with arsenazo M has been made. The rare earths in ion-exchange resins can be directly determined by spectrophotometry after being leached with hydrochloric acid and at heated condition. The rare earths with arsenazo M or a red complex. The maximum absorption of the complex is at 640 nm, and the molar absorption is 8.0 x 10 4 L centre dot mol -1 centre dot cm -1 . While the range of determination is 0.005%-0.5% and 0.001-1.0 g/L, the relative standard deviation is less than 5%, and recovery of rare earths is 98.5-105%. The method is rather simple and rapid

  19. Rare earth industries; Moving Malaysia's Green Economy Forward

    International Nuclear Information System (INIS)

    2011-08-01

    There is a famous saying, Where there is risk, there is opportunity. Rare earths present both health and environmental risks as well as potential economic opportunities. However, the risks are manageable thanks to improved technologies and a better understanding of the implications on health and the environment. This explains why there is a rush by many countries to reopen old mines and increase investment in the production of rare earths concentrate and their high value downstream products. Why is there such a scramble to risk money on rare earths? What have ignited global demand? Where are the opportunities? How are the risks associated with rare earths managed? Can Malaysia benefit from this new growth industry? What should be our strategies? This report, produced by the joint Working Group of the Academy of Sciences Malaysia (ASM) and the Majlis Professor Negara (MPN), discusses the science of rare earths and their business prospects; and proposes some strategic directions for Malaysia. The analysis is based on information culled from various secondary sources as well as the groups engagement with experts from the Rare Earths Society of China. (author)

  20. An Overview of Rare Earth Science and Technology

    Science.gov (United States)

    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.

  1. Investigation of a less rare-earth permanent-magnet machine with the consequent pole rotor

    Science.gov (United States)

    Bai, Jingang; Liu, Jiaqi; Wang, Mingqiao; Zheng, Ping; Liu, Yong; Gao, Haibo; Xiao, Lijun

    2018-05-01

    Due to the rising price of rare-earth materials, permanent-magnet (PM) machines in different applications have a trend of reducing the use of rare-earth materials. Since iron-core poles replace half of PM poles in the consequent pole (CP) rotor, the PM machine with CP rotor can be a promising candidate for less rare-earth PM machine. Additionally, the investigation of CP rotor in special electrical machines, like hybrid excitation permanent-magnet PM machine, bearingless motor, etc., has verified the application feasibility of CP rotor. Therefore, this paper focuses on design and performance of PM machines when traditional PM machine uses the CP rotor. In the CP rotor, all the PMs are of the same polarity and they are inserted into the rotor core. Since the fundamental PM flux density depends on the ratio of PM pole to iron-core pole, the combination rule between them is investigated by analytical and finite-element methods. On this basis, to comprehensively analyze and evaluate PM machine with CP rotor, four typical schemes, i.e., integer-slot machines with CP rotor and surface-mounted PM (SPM) rotor, fractional-slot machines with CP rotor and SPM rotor, are designed to investigate the performance of PM machine with CP rotor, including electromagnetic performance, anti-demagnetization capacity and cost.

  2. Influence of Iron in AlSi10MgMn Alloy

    Directory of Open Access Journals (Sweden)

    Žihalová M.

    2014-12-01

    Full Text Available Presence of iron in Al-Si cast alloys is common problem mainly in secondary (recycled aluminium alloys. Better understanding of iron influence in this kind of alloys can lead to reduction of final castings cost. Presented article deals with examination of detrimental iron effect in AlSi10MgMn cast alloy. Microstructural analysis and ultimate tensile strength testing were used to consider influence of iron to microstructure and mechanical properties of selected alloy.

  3. Green inhibitors. Rare Earth based systems

    International Nuclear Information System (INIS)

    Aballe, A.; Bethencourt, M.; Botana, F.J.; Perez, J.; Rodriguez, M.A.; Marcos, M.

    1997-01-01

    Lanthanum, Cerium and Samarium chlorides have been investigated as uniform and pitting corrosion inhibitors of AISI 434 and AISI 304 stainless steels and AA 5083 Al-Mg alloy in 3.5% Na Cl aerated aqueous solutions. Their inhibitor power was evaluated by using electrochemical techniques such as Linear and Cyclic Polarisation. In each case, the highest protection degree was found in the solution dropped with 500 ppm of CeCl 3 . Similar results were obtained for additions of 500 ppm of LaCl 3 . Scanning Electron Microscopy and Energy Dispersive Spectroscopy allowed us to confirm the cathodic nature of the inhibition process. (Author) 27 refs

  4. Effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel - Part 1

    International Nuclear Information System (INIS)

    Kim, Soon-Tae; Jeon, Soon-Hyeok; Lee, In-Sung; Park, Yong-Soo

    2010-01-01

    To elucidate the effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel, a metallographic examination, potentiodynamic and potentiostatic polarization tests, a SEM-EDS and a SAM analysis of inclusion, austenite phase and ferrite phase were conducted. The addition of rare earth metals to the base alloy led to the formation of (Mn, Cr, Si, Al, Ce) oxides and (Mn, Cr, Si, Ce) oxides, which improved the resistance to pitting corrosion and caused a decrease in the preferential interface areas for the initiation of the pitting corrosion.

  5. Precipitation of the rare earth double sodium and rare earths from the sulfuric liquor and the conversion into rare earth hydroxides through meta ethic reaction

    International Nuclear Information System (INIS)

    Abreu, Renata D.; Oliveira, Ester F.; Brito, Walter de; Morais, Carlos A.

    2007-01-01

    This work presents the purification study of the rare earths through precipitation of rare earth and sodium (Na TR (SO 4 ) 2 . x H 2 O)) double sulfate and his conversion to rare earths hydroxide TR(OH) 3 by meta ethic reaction through the addition of sodium hydroxide solution to the solid double sulfate. The study used the sulfuric liquor as rare earth sample, generated in the chemical processing of the monazite with sulfuric acid by the Industrias Nucleares do Brasil - INB, Brazil, after the thorium and uranium extraction. The work investigated the influence of the main variables involved in the precipitation of Na TR(SO 4 ) 2 .xH 2 O and in the conversion for the TR(OH) 3 , as follows: type and excess of the precipitation agent, temperature and time reaction. The obtained solid composites were characterized by X-ray diffraction, infrared and chemical analysis. The double sulfate diffractogram indicated the Na TR(SO 4 ) 2 mono-hydrated. The characterization of the metatese products has shown that, for obtaining the complete conversion of NaTR(SO 4 ) 2 .H 2 O into TR(OH) 3 , the reaction must be hot processed (∼70 deg C) and with small excess of Na OH (≤ 5 percent). (author)

  6. Study on Yen Phu rare earth ore concentrate treatment technology and separation of major heavy rare earth elements by solvent extraction method

    International Nuclear Information System (INIS)

    Le Ba Thuan; Pham Quang Trung; Vu Lap Lai

    2003-01-01

    1. Yenphu rare earth ore concentrate treatment by alkali under pressure: On the base of studying mineral and chemical compositions of Yenphu rare earth ore concentrate containing 28% TREO and conditions for digestion of ore concentrate by alkali under pressure such as ore concentrate/ NaOH ratio, alkali concentration, pressure and temperature at bench scale (100 gram and 5 kg per batch), the optimal conditions for decomposition of REE ore concentrate have been determined. The yield of the decomposition stage is about 90%. The studies on alkali washing, REE leaching by HCl, pH for leaching process, and iron and radioactive impurities removing by Na 2 S + Na 2 PO 4 have been carried out. The obtained results show that mixture of Na 2 S 5% + Na2PO 4 1% is effective in iron and radioactive impurities removing. The obtained REE oxides get purity of > 99% and meet the need of solvent extraction (SX) individual separation of rare earth elements. The schema for recovery of REEs from Yenphu REE ore concentrate by alkali decomposition under high pressure has been proposed. 2. Fractionation of Yenphu rare earth mixture into subgroups by solvent extraction with PC88A: On the base of simulation program, the parameters for fractional process of rare earths mixture into subgroups by solvent extraction with PC88A have been proposed and determined by experimental verification on mixer-settler set. According to this process, rare earths mixture fractionated into yttrium and light subgroups. In their turn, the light subgroup was separated into light (La, Ce, Pr, Nd) and middle (Sm, Eu, Gd) subgroups. The average yield of the process reached value > 95%. The composition of light subgroup meets the needs for individual separation of Gd, Eu, and Sm. 3. Separation and purification of yttrium: The process for recovery of yttrium consists of two stages: upgrade to get high quality Y concentrate by PC88A and purification by Aliquat 336 in NH 4 SCN-NH 4 Cl medium. The process parameter for

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

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan James

    2014-01-01

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

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

    Science.gov (United States)

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

    2018-05-01

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

  9. STRUCTURE FORMATION OF ALLOYS ON IRON BASIS AFTER LASER ALLOYING

    Directory of Open Access Journals (Sweden)

    О. V. Diachenko

    2016-01-01

    Full Text Available The paper is devoted to investigations on influence of laser treatment regimes of gas-thermal and adhesive coatings from self-fluxing powders on iron basis and after melting with modifying plaster on their roughness and phase composition. One of mathematical planning methods that is a complete factor experiment method has been used for investigation of parameters’ influence on micro-geometry of coatings. The executed investigations have made it possible to observe a general regularity which does not depend on a type of alloying plaster: while increasing speed of laser beam relatively to treated part, beam diameter value of Ra parameter is becoming less. Decrease in height of surface irregularities in case of increasing laser beam speed is related with intensification of evaporation processes. An increase in beam diameter diminishes Ra parameter of the surface. This is due to the fact that decrease in power density occurs at high rate of beam defocusing. Overlapping coefficient does not exert a pronounced effect on Ra parameter of fused coatings. While increasing the speed of laser beam relatively to the part structure is transferred from dendrite into supersaturated one with carbide and boride precipitations. It has been established that technological parameters of laser treatment and particularly speed of laser beam influence on coating composition. While increasing the speed up to v5 = 5 × 10–3 m/s amount of chromium has become larger by 1.5-fold that resulted in increase of micro-hardness of the coating from 9.5–10.1 GPa up to 11.04–15.50 GPa.

  10. Effects of Rare Earth Elements on Properties of Ni-Base Superalloy Powders and Coatings

    Directory of Open Access Journals (Sweden)

    Chunlian Hu

    2017-02-01

    Full Text Available NiCrMoY alloy powders were prepared using inert gas atomization by incorporation of rare earth elements, such as Mo, Nb, and Y into Ni60A powders, the coatings were sprayed by oxy-acetylene flame spray and then remelted with high-frequency induction. The morphologies, hollow particle ratio, particle-size distribution, apparent density, flowability, and the oxygen content of the NiCrMoY alloy powders were investigated, and the microstructure and hardness of the coatings were evaluated by optical microscopy (OM. Due to incorporation of the rare earth elements of Mo, Nb, or Y, the majority of the NiCrMoY alloy particles are near-spherical, the minority of which have small satellites, the surface of the particles is smoother and hollow particles are fewer, the particles exhibit larger apparent density and lower flowability than those of particles without incorporation, i.e., Ni60A powders, and particle-size distribution exhibits a single peak and fits normal distribution. The microstructure of the NiCrMoY alloy coatings exhibits finer structure and Rockwell hardness HRC of 60–63 in which the bulk- and needle-like hard phases are formed.

  11. Constitution and magnetism of iron and its alloys

    CERN Document Server

    Pepperhoff, Werner

    2001-01-01

    Iron played an important role in the development of the industrial society and has not lost any of its significance since today. This book provides the foundations of understanding the physical nature of iron and its alloys. Basics and recent developments concerning its constitution and magnetism are presented as well as its thermal properties. The exceptional role of iron with its wide spectrum of most different technological and physical properties relies on its versatility, its polymorphism of its crystal structure and its magnetism. Therefore it is the aim of the book to link together the constitution and magnetism of iron.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-05

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

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

    International Nuclear Information System (INIS)

    Garai, Mrinmoy; Karmakar, Basudeb

    2016-01-01

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO_2, Nd_2O_3, Sm_2O_3 and Gd_2O_3 doped K_2O−MgO−B_2O_3−Al_2O_3−SiO_2−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm"−"3) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T_g) and crystallization temperature (T_c). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg_3(AlSi_3O_1_0)F_2 by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10"−"6/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque fluorophlogopite mica glass-ceramics by single-step heat treatment. • Nanocrystalline glass

  14. Neutron activation analysis of rare earths in uranium containing rocks

    International Nuclear Information System (INIS)

    May, S.; Pinte, G.

    1984-01-01

    The determination of rare earths by activation analysis in uranium rocks is disturbed either by fission-produced rare earths, or by neptunium-239 originating from uranium-238. In order to eliminate these interferencies, the chemical separation of rare earths from uranium prior to activation should be performed. The chemical process is as follows: the rock sample is fused with sodium borate, then, after addition of hydrochloric acid, the resulting solution is passed through a Dowex 1x8 column. Uranium is retained on the resin, and rare earths and scandium are eluted. Aluminium is added as a carrier to the solution, and rare earths and scandium are coprecipitated with aluminium hydroxide. This precipitate is irradiated in the nuclear reactor. Gamma spectrometry is used for the determination of earth radionuclide. Activity measurements are performed in successive steps during one month. The following elements are determined: Pr, La, Sm, Nd, Yb, Lu, Ce, Tb, Eu and Sc. The chemical yield is measured by using scandium as an internal standard. (author)

  15. Squeezing clathrate cages to host trivalent rare-earth guests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States); He, Yuping [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Mordvinova, Natalia E. [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Lebedev, Oleg [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Kovnir, Kirill [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States)

    2017-11-01

    Strike difference of the trivalent rare-earth cations from their alkali and alkaline-earth peers is in the presence of localized 4f-electrons and strong spin-orbit coupling. Placing trivalent rare-earth cations inside the fullerene molecules or in between the blocks of itinerant magnetic intermetallics gave rise to plethora of fascinating properties and materials. A long-time missing but hardly desired piece is the semiconducting or metallic compound where rare-earth cations are situated inside the oversized polyhedral cages of three-dimensional framework. In this work we present a synthesis of such compounds, rare-earth containing clathrates Ba8-xRxCu16P30. The unambiguous proofs of their composition and crystal structure were achieved by a combination of synchrotron powder diffraction, time-of-flight neutron powder diffraction, scanning-transmission electron microscopy, and electron energy-loss spectroscopy. Our quantum-mechanical calculations and experimental characterizations show that the incorporation of the rare-earth cations significantly enhances the hole mobility and concentration which results in the drastic increase in the thermoelectric performance.

  16. Spectrographic determination of some rare earths in thorium compounds

    International Nuclear Information System (INIS)

    Brito, J. de.

    1977-01-01

    A method for spectrographic determination of Gd, Sm, Dy, Eu, Y, Yb, Tm and Lu in thorium compounds has been developed. Sensibilities of 0.01 μg rare earths/g Th02 were achieved. The rare earth elements were chromatographycally separated in a nitric acid-ether-cellulose system. The solvent mixture was prepared by dissolving 11% of concentrated nitric acid in ether. The method is based upon the sorption of the rare earths on activated cellulose, the elements being eluted together with 0.01 M HNO 3 . The retention of the 152 , 154 Eu used as tracer was 99,4%. The other elements showed recoveries varying from 95 to 99%. A direct carrier destillation procedure for the spectrochemical determination of the mentioned elements was used. Several concentrations of silver chloride were used to study the volatility behavior of the rare earths. 2%AgCl was added to the matrix as definite carrier, being lantanum selected as internal standard. The average coefficient of variation for this method was +- -+ 7%. The method has been appleid to the analysis of rare earths in thorium coumpounds prepared by Thorium Purification Pilot Plant at Atomic Energy Institute, Sao Paulo [pt

  17. Mineral characterisation of Don Pao rare earth deposit in Vietnam

    International Nuclear Information System (INIS)

    XuanBen, T.

    1998-01-01

    Full text: The Don Pao Rare Earth Deposit was discovered in 1959 in Phon Tho district, about 450km North-West of Hanoi capital. Geological work was conducted between 1959-95, resulting in 60 ore bodies of various sizes being identified. The ore bodies are irregularly shaped nests, lenses and veins hosted in the shear zone, at the margin of a Paeleogene aged syenite massif. The mineral composition of Don Pao Deposit is very complex, consisting of more than 50 minerals. Among them, basnaesite, parisite, fluorite and barite are the main constituent minerals of the ore. All the minerals were identified by the modern methods of mineralogical studies. Based on the constituent mineral ratios, four ore types have been distinguished in the deposit: 1. Rare earth ore containing over 5 percent of RE 2 O 3 . 2. Rare Earth-Barite ore containing 0.5 to 30 percent of RE 2 O 3 . 3. Rare Earth-Barite-Fluorite ore containing 1 to 5 percent of RE 2 O 3 . 4. Rare Earth bearing Fluorite ore containing 1 to 5 percent of RE 2 O 3 . According to the benefication test, the ores in Don Pao can be enriched to a concentrate of 60 percent of RE 2 O 3 with a recover of 75 percent

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

    Directory of Open Access Journals (Sweden)

    Cristina Bumbac

    2013-01-01

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

  19. Rare earth permanent magnets in China: production and raw materials

    International Nuclear Information System (INIS)

    Luo, Y.

    1998-01-01

    With the development of computer, electronics, communication and modern information industries, NdFeB magnet industry is growing rapidly as a booming business worldwide. Based on the abundance of rare earth and manpower, supporting by the technical teams and the huge domestic market, China NdFeB magnet industry made big jump during the last decade. Its growth rate is the highest one among all other countries. Now China occupies number one place in the world not only due to its richest rare earth reserves, but also due to its output of rare earth, especially, its sales to the international market. China is the only country, who is able to meet the market needs of rare earth worldwide. The current situation of NdFeB magnet industry can be concluded as ''five highs'', i.e. ''high volume growth'', ''high grade development'', ''high expansion of capacity'', ''high value added product'' and ''high variation speed''. The connotations of these ''five highs'' and a brief review on Chinese rare earth industry will be given in this paper. (orig.)

  20. Solid - solid and solid - liquid phase transitions of iron and iron alloys under laser shock compression

    Science.gov (United States)

    Harmand, M.; Krygier, A.; Appel, K.; Galtier, E.; Hartley, N.; Konopkova, Z.; Lee, H. J.; McBride, E. E.; Miyanishi, K.; Nagler, B.; Nemausat, R.; Vinci, T.; Zhu, D.; Ozaki, N.; Fiquet, G.

    2017-12-01

    An accurate knowledge of the properties of iron and iron alloys at high pressures and temperatures is crucial for understanding and modelling planetary interiors. While Earth-size and Super-Earth Exoplanets are being discovered in increasingly large numbers, access to detailed information on liquid properties, melting curves and even solid phases of iron and iron at the pressures and temperatures of their interiors is still strongly limited. In this context, XFEL sources coupled with high-energy lasers afford unique opportunities to measure microscopic structural properties at far extreme conditions. Also the achievable time resolution allows the shock history and phase transition mechanisms to be followed during laser compression, improving our understanding of the high pressure and high strain experiments. Here we present recent studies devoted to investigate the solid-solid and solid-liquid transition in laser-shocked iron and iron alloys (Fe-Si, Fe-C and Fe-O alloys) using X-ray diffraction and X-ray diffuse scattering. Experiment were performed at the MEC end-station of the LCLS facility at SLAC (USA). Detection of the diffuse scattering allowed the identification of the first liquid peak position along the Hugoniot, up to 4 Mbar. The time resolution shows ultrafast (between several tens and several hundreds of picoseconds) solid-solid and solid-liquid phase transitions. Future developments at XFEL facilities will enable detailed studies of the solid and liquid structures of iron and iron alloys as well as out-of-Hugoniot studies.

  1. Deep-sea mud in the Pacific Ocean as a potential resource for rare-earth elements

    Science.gov (United States)

    Kato, Yasuhiro; Fujinaga, Koichiro; Nakamura, Kentaro; Takaya, Yutaro; Kitamura, Kenichi; Ohta, Junichiro; Toda, Ryuichi; Nakashima, Takuya; Iwamori, Hikaru

    2011-08-01

    World demand for rare-earth elements and the metal yttrium--which are crucial for novel electronic equipment and green-energy technologies--is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements. However, seafloor sediments have not been regarded as a rare-earth element and yttrium resource, because data on the spatial distribution of these deposits are insufficient. Here, we report measurements of the elemental composition of over 2,000 seafloor sediments, sampled at depth intervals of around one metre, at 78 sites that cover a large part of the Pacific Ocean. We show that deep-sea mud contains high concentrations of rare-earth elements and yttrium at numerous sites throughout the eastern South and central North Pacific. We estimate that an area of just one square kilometre, surrounding one of the sampling sites, could provide one-fifth of the current annual world consumption of these elements. Uptake of rare-earth elements and yttrium by mineral phases such as hydrothermal iron-oxyhydroxides and phillipsite seems to be responsible for their high concentration. We show that rare-earth elements and yttrium are readily recovered from the mud by simple acid leaching, and suggest that deep-sea mud constitutes a highly promising huge resource for these elements.

  2. Improvement of magnetocaloric properties of Gd-Ge-Si alloys by alloying with iron

    Directory of Open Access Journals (Sweden)

    Erenc-Sędziak T.

    2013-01-01

    Full Text Available The influence of annealing of Gd5Ge2Si2Fex alloys at 1200°C and of alloying with various amount of iron on structure as well as thermal and magnetocaloric properties is investigated. It was found that annealing for 1 to 10 hours improves the entropy change, but reduces the temperature of maximum magnetocaloric effect by up to 50 K. Prolonged annealing of the Gd5Ge2Si2 alloy results in the decrease of entropy change due to the reduction of Gd5Ge2Si2 phase content. Addition of iron to the ternary alloy enhances the magnetocaloric effect, if x = 0.4 – 0.6, especially if alloying is combined with annealing at 1200°C: the peak value of the isothermal entropy change from 0 to 2 T increases from 3.5 to 11 J/kgK. Simultaneously, the temperature of maximum magnetocaloric effect drops to 250 K. The changes in magnetocaloric properties are related to the change in phase transformation from the second order for arc molten ternary alloy to first order in the case of annealed and/or alloyed with iron. The results of this study indicate that the minor addition of iron and heat treatment to Gd-Ge-Si alloys may be useful in improving the materials’ magnetocaloric properties..

  3. Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

    Science.gov (United States)

    Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

    2016-02-01

    Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

  4. Antiferromagnetic domains in rare earth metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, S B [Hull Univ. (UK). Dept. of Applied Physics

    1975-12-01

    Anomalies in the c-axis elastic properties of antiferromagnetic Dy, 50% Tb-Ho and 60% Gd-Y are reported. The anomalies are only present when the sample is cycled from the ferromagnetic to the antiferromagnetic state and are attributed to domains in the helical regime.

  5. Redox reactions in rare earth chloride molten electrolytes

    International Nuclear Information System (INIS)

    Khokhlov, V.A.; Novoselova, A.V.; Nikolaeva, E.V.; Tkacheva, O.Yu.; Salyulev, A.B.

    2007-01-01

    Rare earth (REM, Ln) solutions in chloride melts including MCI+LnCl 3 mixtures, where M - alkali metals, were investigated by potentiometry, voltammetry, conductometry in wide concentration and temperature intervals. Findings present complete and trusty information on the valent state of rare earths, structure and composition of complex ions affecting essentially on properties of electrolytes. It is demonstrated that the coexistence of rare earth ions with different oxidation level formed as a result of possible redox reactions: 2Ln 3+ + Ln ↔3Ln 2+ , Ln 2+ + Ln↔2Ln + and nM + + Ln↔nM + Ln n+ appears sharply in thermodynamic and transport properties of molten Ln-LnCl 3 and Ln-LnCl 3 -MCl systems [ru

  6. Determination of the heavy rare earth radionuclides in melted rock

    International Nuclear Information System (INIS)

    Li Yinming; Wang Yalong; Zhang Quanshi

    1995-01-01

    There are some heavy rare earth radionuclides in the melted rocks, such as 160 Tb, 168,170 Tm, 88,91 Y, 174,177 Lu, 169 Yb, etc.. Because their contents are very low in the melted rocks and the light rare earth fission products are interfered with their determination, it is very complicated to measure them quantitatively. So a new method has been studied in which P507 resin is used to separate and purify the rare earths. Radioactive sources are prepared by the pieces of filter paper for determining chemical yield with X-fluorescence analysis, and radioactive activity is determined with the γ-spectra analysis. It is proved that this method has satisfied the demands of experiments

  7. Spectroscopic properties of rare earths in optical materials

    CERN Document Server

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

    2005-01-01

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

  8. Determination of rare earth impurities in thorium by spectrographic methods

    Energy Technology Data Exchange (ETDEWEB)

    Wray, L W

    1957-08-15

    A method for determining rare earth impurities in thorium in the fractional ppm range is described. Before spectrographic examination is possible, the impurities must be freed from the thorium matrix. This is accomplished by removing the bulk of the thorium by extraction with TBP-CCl{sub 4} and the remainder by extraction with TTA-C{sub 6}H{sub 6}. This results in a consistent recovery of rare earths of about 85% with an average sensitivity of 0.2 ppm. The experimental error is within 10%. Details of the procedure are given together with working curves for the major neutron absorbing rare earths; i.e. dysprosium, europium, gadolinium and samarium. (author)

  9. Investigation and modelling of rare-earth activated waveguide structures

    International Nuclear Information System (INIS)

    Wolinski, W.; Malinowski, M.; Mossakowska-Wyszynska, A.; Piramidowicz, R.; Szczepanski, P.

    2005-01-01

    In this paper the overview of the recent study on the rare-earth activated waveguides performed in the Optoelectronic Department of IMiO is presented. We reported on the development of rare earth-doped fluorozirconate (ZBLAN) glass fibers that allow a construction of a new family of visible and ultraviolet fiber lasers pumped by upconversion. Especially the performance of holmium devices is presented. The properties of laser planar waveguides obtained by the LPE process and the growth conditions of rare earths doped YAG layers are presented. In this paper we present also the theoretical study of the nonlinear operation of planar waveguide laser, as an example the microdisk Nd:YAG structure is discussed. We derived an approximate formula which relates the small signal gain in the Nd:YAG active medium and the laser characteristics, obtained for whispering-gallery modes and radial modes, to the output power and real parameters of the laser structure (authors)

  10. Investigation of sulphides in iron alloys of high purity

    International Nuclear Information System (INIS)

    Wyjadlowski, T.

    1973-01-01

    This research thesis reports the study of the morphology and composition of sulphides in iron alloys with respect to metal composition and to the nature of impurities. In order to understand the specific action of each addition on inclusion morphology, this work has started with high-purity alloys (binary alloys and then ternary alloys). The author studied whether solubility variations would entail either intergranular or intragranular or hybrid iron sulphide precipitation. He examined whether sulphide morphology is depending on thermal treatment, and whether equilibrium precipitates were different in terms of morphology and composition at high and room temperature. He studied the influence of addition elements on sulphide morphology and composition, an important issue as some elements may reduce brittleness. These elements are classified in terms of affinity with sulphur

  11. Peculiarities of rare-earth-element distribution in environmental objects

    International Nuclear Information System (INIS)

    Gorbunov, A.V.; Onischenko, T.L.; Gundorina, S.F.; Frontasyeva, M.V.

    1993-01-01

    The effect of the production of phosphorus fertilizers on the pollution of the environment by rare-earth elements is reviewed. The main sources of rare-earth element pollution in the environment are described. The levels of REEs in components of the environment - atmosphere, snow, different types of soil, native and agricultural types of vegetation - that provide evidence for their participation in the biological cycle of plants are considered. The high values of the correlation coefficients lead one to think that the REE distribution in vegetation occurs under specific laws true for this family of elements. (author) 9 refs.; 6 figs.; 5 tabs

  12. Rare earth aerosol analysis by x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Citron, I.M.; Mausner, L.F.

    1982-01-01

    An analytical method for the determination of four lanthanides in air filter samples is described. The method involves simultaneous quantitative determinations of La, Ce, Pr, and Nd at the microgram level by x-ray fluorescence spectrometry without chemical separation of these rare earths and without serious interferences from the dust matrices on the filters. The method has been used successfully to analyze some air filter samples collected at a rare earth processing refinery in Illinois. A description of the development of the method is given as well as the results obtained by using this method on the air filter samples. The reproducibility of the results was generally +-5%

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

    DEFF Research Database (Denmark)

    Høgberg, Stig; Holbøll, Joachim; Mijatovic, Nenad

    2017-01-01

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

  14. Process to remove rare earth from IFR electrolyte

    International Nuclear Information System (INIS)

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

    1994-01-01

    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. 1 fig

  15. Contribution for the studies of rare earth dithionates

    International Nuclear Information System (INIS)

    Schmitz, L.C.

    1988-01-01

    The main objective of this work is the synthesis and investigation of some properties of rare earth dithionates. The rare earth dithionates were prepared from the respective sulphates, by the reaction of the latter with BaS sub(2) O sub(6) in aqueous solutions. The lanthanide ion content was estimated by complexometric titration with EDTA; analysis for H were carried out by microanalysis and the water content was determinated by Karl Fischer titration. This experimental results in addition to thermogravimetric (TG) data gave the stoichiometry of the compounds. (author)

  16. Concentration of light rare earths process by amoniacal precipitation

    International Nuclear Information System (INIS)

    Aguilera, Y.; Rapado, M.; Consuegra, R.

    1996-01-01

    A procedure for the separation and concentration of light rare earths using a mixture of ammonia and water was developed. As a result technical concentrates of rare earths were obtained and the physical separation in the filtration step was improved. The filtration parameters (cake resistance r 0 and filtration web resistance R) were obtained for this process being they 5,5.10 11 cm/g and 3,4.10 13 cm -1 respectively. The proposed technology concentrates (Ce, La and Nd) with purities ranging from: 85-90 %, 85-87 % and 42-65 % respectively in only one precipitation step

  17. Spectrofluorimetric determination of rare earth elements using solidmatrix

    International Nuclear Information System (INIS)

    Suh, I.S.; Chi, K.Y.

    1982-01-01

    In this experiment, rare earth elements are separated from uranium by using the alumina column, anion exchange resin column, and 20% TOA in xylene and fluorescence characteristics were found in the solid matrix to analyze these elements without preseparation from each other. It becomes clear that the YVO 4 matrix is more sensitive than the Y 2 O 3 matrix when the red filter is used to minimized the second order peak intensity. And micro quantity of the rare earth elements in the yellow cake are analyzed by the using of the YVO 4 soid matrix. (Author)

  18. Synthesis and physicochemical investigation of adducts of rare earth thenoyltrifluoroacetonates

    Energy Technology Data Exchange (ETDEWEB)

    Anufrieva, S.I.; Snezhko, N.I.; Martynenko, L.I.; Pechurova, N.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1982-11-01

    Adducts of rare earth thenoyltrifluoroacetonates (3) have been synthesized with tributylphosphate (TBP), trioctylphosphenoxide (TOPO), triphenylphosphenoxide (TPO) of 1:1 and 1:2 composition as well as with ..cap alpha.., ..cap alpha..'-dipyridine (Dipy), o-phenanthroline (Phen) of 1:1 composition. The separated adducts have been studied by methods of element analysis, X-ray phase and derivatographic analyses and IR spectroscopy. It is shown that the adducts are more thermostable compared to the corresponding rare earth thenoyltrifluoroacetonate hydrates.

  19. Rare Earths and Clean Energy: analyzing China's upper hand

    International Nuclear Information System (INIS)

    Seaman, J.

    2010-01-01

    An ominous but avoidable resource crunch in the so-called 'rare earth elements' is now threatening the development of a number of key industries from energy to defense to consumer electronics. As key components in the latest generation of technologies, including specialized magnets for windmills and hybrid cars, lasers for range finders and 'smart' munitions, and phosphors for LCD screens, demand for these rare metals is expected to grow rapidly in the years to come. But decades of under-investment in the mining and separation of these elements across the globe has left the industry ill-prepared to meet thi s growing demand. Over the years, only China has recognized the strategic significance of these resources and has succeeded in gaining a near monopoly on production, currently churning out 97% of the world' s rare earth oxides. Faced with problems of its own, and eager to use its resource advantage to master higher levels of value-added production of rare earth-dependent products, China has increasingly limited the rest of the world's access to these raw materials. This only complicates what was already projected to be a problematic resource shortage. This issue demands a higher quality of public debate. Rare earth consuming countries outside of China have only recently become aware of their dependence and started to take stock of the risks. Time is of the essence. Bringing new supplies online to meet growing demand is a long, complicated and risky process but is nevertheless necessary to ensure the development of high tech industries, notably clean energy. Accessible reserves of rare earths do exist outside of China and mitigating the effects of the looming shortage requires opening up these reserves to production. Yet, as the Chinese experience attests, there are substantial risks to the environment associated with mining and separating rare earths. Care must be taken to ensure responsible mining practices across the globe. Longer-term solutions, such as

  20. Recovery and purification of rare earth elements and thorium

    International Nuclear Information System (INIS)

    Sungur, A.; Saygi, Z.; Yildiz, H.

    1985-01-01

    Rare earth elements and thorium found in the low-grade Eskisehir-Beylikahir ore have been recovered by HCl leaching, Lanthanides and thorium were separated and purified from the leach solutions through the precipitation sequence as double sulphate, hydroxide and oxalate. The Ln 2 O 3 and Th(OH) 4 products, finally obtained contained 36% Ce and 65% Th. The analysis of rare earth elements, thorium and other present ingredients were carried out by instrumental neutron activation analysis, atomic absorption spectroscopy, vis-spectroscopy and gravimetry. (author)

  1. Uptake of rare earth elements by dryopteris erythrosora (autumn fern)

    International Nuclear Information System (INIS)

    Ozaki, Takuo; Enomoto, Shuichi

    2001-01-01

    Mechanisms of uptake of rare earth elements (REEs) were investigated, particularly those by REE accumulator species (autumn fern). Rare earth elements are practically insoluble under natural conditions, suggesting some unknown mechanisms in REE accumulator species. In the present investigation, two notable phenomena were observed. (1) Concerning the ionic-radius dependence of REE uptake by leaves, nonaccumulator species showed an extremely high uptake for Y compared with the adjacent-ionic-radius REEs in the multitracer, while accumulator species showed no anomaly. (2) REE uptake by autumn fern was influenced by the addition of chelating chemical reagents in the uptake solution, while no effect was observed for nonaccumulator species. (author)

  2. Separation of rare earth metal using micro solvent extraction system

    International Nuclear Information System (INIS)

    Nishihama, S.; Tajiri, Y.; Yoshizuka, K.

    2005-01-01

    A micro solvent extraction system for the separation of rare earth metals has been investigated. The micro flow channel was fabricated on a PMMA plate. Extraction equilibrium was quickly achieved, without any mechanical mixing. The solvent extraction results obtained for the Pr/Sm binary solutions revealed that both rare earth metals are firstly extracted together. Following, the Pr is extracted in the organic solution and Sm remains in the aqueous phase. The phase separation can be successively achieved by contriving the cross section of the flow channel

  3. Iron titanium manganase alloy hydrogen storage

    Science.gov (United States)

    Reilly, James J.; Wiswall, Jr., Richard H.

    1979-01-01

    A three component alloy capable of reversible sorption of hydrogen having the chemical formula TiFe.sub.1-x Mn.sub.x where x is in the range of about 0.02 to 0.5 and the method of storing hydrogen using said alloy.

  4. Evolution of Mg-5Al-0.4Mn microstructure after rare earth elements addition

    Directory of Open Access Journals (Sweden)

    A. Żydek

    2011-04-01

    Full Text Available Mg-5Al-0.4Mn-xRE (x = 0, 1, 2, 3 wt.% magnesium alloys were prepared successfully by casting method. The microstructure wasinvestigated by light microscopy. The influence of rare earth (RE elements on the area fraction of eutectic was analysed. The obtainedresults revealed that the as-cast Mg-5Al-0.4Mn alloy consist of α - Mg matrix and eutectic α + γ (where γ is Mg17Al12. However, whilerare earth elements were added to the Mg-Al type alloy, Al11RE3 precipitates were formed. The amount of the Al11RE3 precipitatesincreased with increasing addition of RE, but the amount of γ - Mg17Al12 decreased.

  5. Crystal fields in Sc, Y, and the heavy-rare-earth metals Tb, Dy, Ho, Er, Tm, and Lu

    International Nuclear Information System (INIS)

    Touborg, P.

    1977-01-01

    Experimental investigations of the magnetic poperties of dilute alloys of the rare-earth solutes Tb, Dy, Ho, Er, and Tm in the nonmagnetic hosts Lu, Y, and Sc have been performed. These measurements, which include and supplement earlier published results, have been analyzed and crystal-field parameters for all these 15 alloy systems deduced. The consistency of the parameters was confirmed by a variety of magnetic measurements, including neutron spectroscopy. Crystal-field parameters have also been derived for the ions in pure magnetic rare-earth metals and their alloys using the results for the dilute alloys supplemented with paramagnetic measurements up to high temperatures on the concentrated systems. Mean values and standard deviations of the higher-order crystal-field parameters for all Y and Lu alloys are B 40 /β = 6.8 +- 0.9 K, B 60 /γ = 13.6 +- 0.7 K, and B 66 /γ = (9.7 +- 1.1) B 60 /γ. These values: with the inaccuracies somewhat increased: are expected to be representative also for the magnetic rare-earth metals. For rare-earth ions in the Sc host the values B 40 /β = 9.9 +- 1.9 K, B 60 /γ = 19.8 +- 1.5 K, and B 66 /γ = (9.4 +- 0.9) B 60 /γ were deduced. B 20 /α is a host-sensitive parameter which has the average values of -102.7, -53.4, and 29.5 K for rare-earth ions in Y, Lu, and Sc, respectively. There is also evidence that this parameter varies with the solute. B 20 /α for ions in the pure magnetic rare-earth metals and their alloys shows a linear variation with c/a ratio characteristic of each ion. The results indicate a contribution from anisotropic exchange to the high-temperature paramagnetic anisotropy of approximately 20% for Tb, Dy, Ho, and Er, and approximately 10% for Tm

  6. Determination of rare earth elements in red mud by ICP-MS

    International Nuclear Information System (INIS)

    Kumar, Sanjukta A.; Suvarna, S.; Kiran Kumar, G.

    2017-01-01

    Red mud or red sludge is a highly alkaline waste product composed mainly of iron oxide that is generated in the industrial production of aluminum from bauxite. With about 77 million tons of this hazardous material being produced annually, red mud poses a serious disposal problem in the mining industry. Discharge of red mud is hazardous environmentally because of its alkalinity. Many studies have been conducted to develop uses of red mud. An estimated 2 to 3 million tones are used annually in the production of cement, road construction and as a source for iron. Potential applications include the production of low cost concrete, application to sandy soils to improve phosphorus cycling, amelioration of soil acidity, landfill capping and carbon sequestration. Red mud contains a large amount of iron along with appreciable concentrations of many strategic elements such as rare earth elements and therefore can be a source of valuable secondary raw material. This necessitates the elemental characterization of red mud. This paper presents an effective dissolution procedure using a mixture of phosphoric acid and nitric acid for red mud followed by determination of rare earth elements by ICP-MS. The method was validated by spike recovery experiments. The recoveries were found within 98 to 102 %. The relative standard deviation (RSD) of the method was found to be within 5 %

  7. Faraday effect in rare-earth ferrite garnets located in strong magnetic fields

    International Nuclear Information System (INIS)

    Valiev, U.V.; Zvezdin, A.K.; Krinchik, G.S.; Levitin, R.Z.; Mukimov, K.M.; Popov, A.I.

    1983-01-01

    The Faraday effect is investigated experimentally in single crystal specimens of rare earth iron garnets (REIG) R 3 Fe 5 O 12 (R=Y, Gd, Tb, Dy, Er, Tm, Yb, Eu, Sm and Ho) and also in mixed iron garnets Rsub(x)Ysub(3-x)Fesub(5)Osub(12) (R=Tb, Dy). The m.easurements are carried out in pulsed magnetic fields of intensity up to 200 kOe, in a temperature range from 4.2 to 300 K and at a wavelength of the light lambda=1.15 μm. The field dependence of the Faraday effect observed in the REIG cannot be explained if only the usually considered ''paramagnetic'' contribution to the Faraday effect is taken into account. A theory is developed which, besides the paramagnetic mechanism, takes into account a diamagnetic mechanism and also the mixing of the wave functions of the ground and excited multiplets. The contributions of each of these three mechanisms to the angle of rotation of the plane of polarization by the rare earth sublattice of the iron garnet are estimated theoretically. It is concluded that the mixing mechanism contributes significantly to the field and temperature dependences of the Faraday effect in REIG

  8. Micromagnetics of rare-earth efficient permanent magnets

    Science.gov (United States)

    Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

    2018-05-01

    The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

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

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

    -phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4...

  10. Supramolecular structures constructed from three novel rare earth ...

    Indian Academy of Sciences (India)

    Supramolecular structures constructed from three novel rare earth metal complexes. HUAZE DONGa,∗, XIAOJUN FENGb,∗, XIA LIUc, BIN ZHENGa, JIANHONG BIa, YAN XUEa,. SHAOHUA GOUd and YANPING WANGa. aDepartment of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.

  11. Crystallization of mixed rare earth (didymium) molybdates in silica gel

    Indian Academy of Sciences (India)

    Experiments on the growth of mixed rare earth (didymium—a combination of La, Nd, Pr and Sm) molybdates in silica gel medium are reported. The optimum conditions conducive for the growth of these crystals are described and discussed. Concentration programming is reported to enhance the size of crystals by two-fold; ...

  12. A divalent rare earth oxide semiconductor: Yttrium monoxide

    Science.gov (United States)

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

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

  13. Dissolved rare earth elements in the Black Sea

    NARCIS (Netherlands)

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

    1991-01-01

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

  14. An introduction to the economics of rare earths

    NARCIS (Netherlands)

    Bartekova, E.

    2014-01-01

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

  15. Advanced system for separation of rare-earth fission products

    International Nuclear Information System (INIS)

    Baker, J.D.; Gehrke, R.J.; Greenwood, R.C.; Meikrantz, D.H.

    1982-01-01

    A microprocessor-controlled radiochemical separation system has been further advanced to separate individual rare-earth elements from mixed fission products in times of a few minutes. The system was composed of an automated chemistry system fed by two approximately 300 μg 252 Cf sources coupled directly by a He-jet to transport the fission products. Chemical separations were performed using two high performance liquid chromatography columns coupled in series. The first column separated the rare-earth group by extraction chromatography using dihexyldiethylcarbamoylmethylphosphonate (DHDECMP) adsorbed on Vydac C 8 resin. The second column isolated the individual rare-earth elements by cation exchange chromatography using Aminex A-9 resin with α-hydroxyisobutyric acid (α-HIBA) as the eluent. Significant results, which have been obtained to date with this advanced system, are the identification of several new neutron-rich rare-earth isotopes including 155 Pm (T=48+-4 s) and 163 Gd (T=68+-3 s). In addition, a half-life of 41+-4 s is reported for 160 Eu. (author)

  16. Production of a tracer packet of heavier rare earth elements

    International Nuclear Information System (INIS)

    Lahiri, S.; Nayak, D.; Maji, S.

    2004-01-01

    Production of a tracer packet of heavier rare earth elements containing carrier-free radionuclides of 153,155 Tb, 153,155,157 Dy, 159 Ho, 159,161 Er, 161 Tm produced by medium energy 7 Li and 12 C irradiation on an europium oxide target and the subsequent separation of bulk europium from the carrier-free products is described. (author)

  17. Recovery of uranium and of rare earths from Moroccan phosphates

    International Nuclear Information System (INIS)

    Ezahr, I.; El Houari, A.; Smani, S.M.

    1984-01-01

    The contents of uranium and of rare earths in Moroccan phosphates vary from 75 to 250 ppm and from 900 to 1500 ppm, respectively. The phosphates produced in Morocco contain therefore about 2500 t of uranium and 25 000 t of rare earths, compared with annual productions of uranium and of rare earths of 43 000 t and 33 000 t, respectively. During the sulphuric leaching of the phosphate ores, uranium is found to 80-90% in the phosphoric acid. Research into the extraction of uranium has shown that for the phosphoric acids produced at Safi the coefficient of extraction: is not very sensitive to the P 2 O 5 concentration on the 28-30% region; is not affected by the sulphur level up to the concentration of 4%; is very sensitive to the fluorine content beyond 1%. On the level of the first cycle of the process in Depa-Topo, four extraction stages permit a yield of between 92 and 98% to be reached. The addition of an oxidizing agent to the phosphoric acids under examination was not necessary, as their potential level is high. The purity of the yellow-cakes obtained varies from 94 to 99%. The overall recovery efficiency lies between 67 and 71%. In a second part, this paper deals with the recovery of the rare earths [fr

  18. On the luminescence of perovskite type rare earth gallates

    International Nuclear Information System (INIS)

    Jianmei, Y.; Qingyuan, W.; Shuzhen, L.; Lianren, S.; Mingyu, C.

    1985-01-01

    It has been reported that perovskite type lanthanum gallates may be a good host material for laser and luminescence, but in the rare earth gallates studied, the numbers of perovskite type are less than that of the garnet type and there is less report on their spectroscopic properties in the literature. In this paper synthesis and spectroscopic properties of these compounds are studied

  19. Allowed unhindered beta connected states in rare earth nuclei

    International Nuclear Information System (INIS)

    Sood, P.C.; Ray, R.S.

    1986-03-01

    The beta-connected states in odd-mass as well as even mass rare earth nuclei, where the transition is of allowed unhindered nature, are listed. The tabulation includes 54 cases of such transitions. Validity of Alaga selection rules is examined and the results are used to assign configurations to the involved single particle and two-particle states. (author)

  20. The symmetries of magnetic structures in rare earth tetraborides

    International Nuclear Information System (INIS)

    Schaefer, W.; Will, G.; Buschow, K.H.J.

    1975-01-01

    The collinear antiferromagnetic spin configurations, which are possible in the rare earth tetraboride structure (space group P 4/mbm) and their distinction by neutron diffraction are discussed. The symmetries of the different antiferromagnetic structures are described by the corrosponding magnetic space groups. Neutron diffraction data collected from ErB 4 are integrated in the structure discussion. (orig.) [de

  1. Rare earth point defects in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Sanna, S.

    2007-12-14

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

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

    NARCIS (Netherlands)

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

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

  3. Preparation and characteristics of various rare earth nitrides

    International Nuclear Information System (INIS)

    Imamura, H.; Imahashi, T.; Zaimi, M.; Sakata, Y.

    2008-01-01

    Active nanocrystalline nitrides of EuN and YbN with high surface areas were successfully prepared by the thermal decomposition of the rare earth amides (Eu(NH 2 ) 2 , Yb(NH 2 ) 2 and Yb(NH 2 ) 3 ). For the preparation of CeN, PrN and NdN, the direct reaction of the rare earth metals with ammonia was extensively studied to determine optimal conditions. In the reaction of rare earth metals with ammonia, hydrides besides the nitrides were competitively formed. The reaction conditions such as temperatures and ratios of ammonia to rare earth metal were crucial in preferential formation of nitride. The nanocrystalline YbN and EuN readily absorbed large amounts of ammonia even at room temperature upon contact with ammonia (13.3 kPa). The absorbed ammonia existed in at least two forms on/in the nitride; the one was surface-adsorbed ammonia and the other ammonia absorbed in the nitride in a decomposed state. The properties of ammonia absorbed by the nitride were further evaluated by temperature-programmed desorption (TPD), FT-IR and XRD techniques

  4. Direct current electroluminescence in rare-earth-doped zinc sulphide

    International Nuclear Information System (INIS)

    Bryant, F.J.; Krier, A.

    1984-01-01

    Some of the properties and characteristics of rare-earth-doped zinc sulphide DCEL devices are reported. Two types of devices are discussed, co-evaporated ZnS:RE thin films and ion implanted ZnS:RE single crystal diodes. The thin film devices exhibit bright DCEL of various colours at low applied voltages (typically approximately 12 V). A study of the spectral intensities and lifetimes of the Er 3+ ion in ZnS:Er 3+ thin films is consistent with a Boltzmann energy distribution amongst the conduction electrons present in these devices. The ZnS:RE single crystal diodes fabricated in this laboratory by ion implantation are also capable of various colour DCEL. By comparing the EL emission obtained from the different rare earth dopants, erbium and neodymium are identified as the most efficient luminescence centres. Further consideration of the EL emission spectra gives evidence for the presence of inter-conduction band hot electron transitions in those devices containing rare earth dopants which are inefficent electroluminescence centres. These findings can be explained in terms of Auger processes occurring in rare earth complexes. (author)

  5. Uncovering the end uses of the rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xiaoyue, E-mail: xiaoyue.du@empa.ch [Swiss Federal Laboratories for Materials Science and Technology (EMPA), Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland); Yale University, 195 Prospect Street, New Haven CT 06511 (United States); Graedel, T.E. [Yale University, 195 Prospect Street, New Haven CT 06511 (United States)

    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. - Highlights: • We have derived the first quantitative end use information of the rare earths (REE). • The results are for individual REE from 1995 to 2007. • The end uses of REE in China, Japan, and the US changed dramatically in quantities and structure. • This information can provide solid foundation for decision and strategy making.

  6. Electrons and Spin Waves in Heavy Rare Earth Metals

    DEFF Research Database (Denmark)

    Mackintosh, A. R.

    1972-01-01

    this understanding on a more quantitative basis. The experimental evidence on the electronic structure of the rare earths is still rather meager but, so far as it goes, is in accord with the detailed description provided by band structure calculations. On the other hand, the experimental study of the magnon...

  7. Mechanism of structural type formation of rare earth polychalcogenides

    International Nuclear Information System (INIS)

    Kuz'micheva, G.M.; Eliseev, A.A.; Khalina, S.Yu.

    1981-01-01

    It proved to be possible to obtain the structural motives not only of all the known polychalcogenides of rare earth elements but to forecast compounds not yet existing on the basis of two initial structural motives. All the structural motives can be divided into superstructures and polytypes as to the mechanism of their formation [ru

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

    Indian Academy of Sciences (India)

    Unknown

    Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium ... syan (1997) has quoted a single value for Gd3Sc2Ga3O12. In the present study measurements have ... small and within the limits of experimental error. There- fore, where pure garnet crystals ...

  9. Rare earth intermetallic compounds produced by a reduction-diffusion process

    International Nuclear Information System (INIS)

    Cech, R.E.

    1975-01-01

    A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

  10. Environmental aspects in the processing of rare earth ores and minerals

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2011-01-01

    In India, rare earths are extracted from the mineral monazite which occurs abundantly along with other heavy minerals in the coastal beach sands. Monazite, apart from rare earths, also contains uranium and thorium. Rare earths can be obtained from monazite either by acid digestion route or by alkaline digestion route. In India, although pilot scale studies have been carried out extraction of rare earths by acid digestion route, however, alkali digestion route has been predominantly followed for commercial extraction of rare earths

  11. Processing and Protection of Rare Earth Permanent Magnet Particulate for Bonded Magnet Applications

    Energy Technology Data Exchange (ETDEWEB)

    Sokolowski, Peter Kelly [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Rapid solidification of novel mixed rare earth-iron-boron, MRE2Fe14B (MRE = Nd, Y, Dy; currently), magnet alloys via high pressure gas atomization (HPGA) have produced similar properties and structures as closely related alloys produced by melt spinning (MS) at low wheel speeds. Recent additions of titanium carbide and zirconium to the permanent magnet (PM) alloy design in HPGA powder (using He atomization gas) have made it possible to achieve highly refined microstructures with magnetic properties approaching melt spun particulate at cooling rates of 105-106K/s. By producing HPGA powders with the desirable qualities of melt spun ribbon, the need for crushing ribbon was eliminated in bonded magnet fabrication. The spherical geometry of HPGA powders is more ideal for processing of bonded permanent magnets since higher loading fractions can be obtained during compression and injection molding. This increased volume loading of spherical PM powder can be predicted to yield a higher maximum energy product (BH)max for bonded magnets in high performance applications. Passivation of RE-containing powder is warranted for the large-scale manufacturing of bonded magnets in applications with increased temperature and exposure to humidity. Irreversible magnetic losses due to oxidation and corrosion of particulates is a known drawback of RE-Fe-B based alloys during further processing, e.g. injection molding, as well as during use as a bonded magnet. To counteract these effects, a modified gas atomization chamber allowed for a novel approach to in situ passivation of solidified particle surfaces through injection of a reactive gas, nitrogen trifluoride (NF3). The ability to control surface chemistry during atomization processing of fine spherical RE-Fe-B powders produced advantages over current processing methodologies. In particular, the capability to coat particles while 'in flight' may eliminate the

  12. Solubility of nitrogen in iron alloys with vanadium and niobium

    International Nuclear Information System (INIS)

    Pomarin, Yu.M.; Grigorenko, G.M.; Lakomskij, V.I.

    1975-01-01

    The solubility of nitrogen in the concentration range under study in Fe-N-V and Fe-N-Nb systems is in compliance with Syverts' law. An equation has been set up so as to estimate the nitrogen solubility in the iron alloys containing up to 10 per cent of vanadium and niobium in the wide temperature range

  13. Change of sulfide inclusions in steel microalloying with rare earth and alkaline-earth elements

    International Nuclear Information System (INIS)

    Averin, V.V.; Polonskaya, S.M.; Chistyakov, V.F.

    1977-01-01

    The conditions for the formation of sulfides in molten and solid iron were determined by considering the thermodynamics of the interaction of sulfur and of oxygen with various components. It was shown in casting of low-carbon steel under a blanket of slag-forming briquettes, calcium of the silicocalcium partly passes to iron and to the sulfide phase. The sulfide inclusions with calcium in rolling become lens-shaped and acquire a greater strength, proportional to the content of calcium, thus ensuring a lesser anisotropy of steel. The change in the shape and the composition of sulfide inclusions effects the fracture of the metal which changes in type from separation along lamellar inclusions to a plastic fracture, i.e., enhances resilience. It is thus noted that rare-earth and alkali-earth elements, in particular, cerium and calcium are promising agents for desulfurating molten iron

  14. Rare earth element lithogeochemistry of granitoid mineral deposits

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, R.P.; Fryer, B.J. (Memorial Univ. of Newfoundland, St. John' s (Canada). Dept. of Earth Sciences)

    1983-12-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl/sup -/ complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F/sup -/ and CO/sub 3//sup 2 -/ become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl/sup -/ versus F/sup -/ versus CO/sub 3//sup 2 -/ in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F/sup -/ and CO/sub 3//sup 2 -/ in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution.

  15. Rare earth element lithogeochemistry of granitoid mineral deposits

    International Nuclear Information System (INIS)

    Taylor, R.P.; Fryer, B.J.

    1983-01-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl - complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO 3 2- become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl - versus F - versus CO 3 2- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F - and CO 3 2- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution

  16. Crystal chemistry and magnetic properties of ternary rare earth sulfides

    International Nuclear Information System (INIS)

    Plug, C.M.; Rijksuniversiteit Leiden

    1977-01-01

    The results of magnetic measurements on two groups of ternary rare earth sulphides are described, the MLnS 2 (M=Li, Na, K) type of compounds and the series Ln 2 ZrS 5 , where Ln denotes one of the rare earths. None of these compounds is metallic, excluding the possibility of RKKY-interaction. In chapter II a survey of the relevant theory on magnetic properties and crystal field splitting is given. In spite of the similarity in chemical properties of the rare earths, the crystal chemistry of their compounds is rather complex. This is due to the lanthanide contraction. The third chapter deals with the description and classification of the numerous crystal structures of both ternary and binary rare earth sulphides that have been observed. Rather simple relations between various structures are presented using a new method of structure classification. The magnetic interactions expected to be based on superexchange via the anions, which is usually very structure dependent. Experiments to study the crystallographic ordering, applying both X-ray and electron diffraction methods and the results of the magnetic measurements on the compounds MLnS 2 are reported in chapter IV. The compounds Ln 2 ZrS 5 are candidates for a systematic study of the variation of the magnetic properties along the rare earth series. The results of magnetic measurements on these compounds are presented in chapter V, combined with the results of specific heat measurements. Also the magnetic structure of two representatives, Tb 2 ZrS 5 and Dy 2 ZrS 5 , determined by neutron diffraction experiments below the ordering temperature, is reported

  17. Separation of Rare Earths from Uranium and Thorium

    International Nuclear Information System (INIS)

    Krebs, Damien

    2014-01-01

    Greenland Minerals and Energy - Key Highlights – A unique world class mining project: 1. World-class, large scale development project: • Economically robust, proven technology, large-scale, long life production of rare earths concentrate and uranium; • Large JORC resource base to produce ~7kt HREO, 37kt LREO & 3Mlbs U_3O_8 per annum over 30 year mine life; • Ideally located near international airport, existing towns and potential hydro-electric power source. 2. Very attractive commodity portfolio: • Heavy rare earths and uranium are both recognised as strategically important commodities for the future; • Rare earths market characterised by limited capacity and increasing demand (particularly Dy, Nd, Tb, Eu and Y). 3. Strong management and technical team: • Experienced management team with proven track record; • Well-respected and knowledgeable technical/project team in place with exceptional local expertise. 4. Highly advantageous ore-type, makes for simple cost-effective processing, highly scalable production: • High upgrade through beneficiation brings optionality to Kvanefjeld project; • Leaching can be done in Greenland, or owing to the high-grade concentrate, can be shipped to other locations; • Allows to single concentrator in Greenland, multiple refineries/partners globally. 5. Globally significant, long life, low cost, multi-commodity asset: • Company to become one of the largest producers of rare earths globally and a significant U_3O_8 mine; • Potential to supply >20% of global critical (including heavy) rare earth element demand; • Company has low cost of production due to multiple by-product opportunities. 6. Low political risk: • Stable, low-risk operating environment with government looking to develop new industries and employment; • GME fully permitted to evaluate the project, exploration licence now includes radioactive elements; • Management and board have a solid working relationship with the government and are

  18. Moessbauer effect studies of magnetic interactions in iron and dilute iron alloys

    International Nuclear Information System (INIS)

    Woude, F. van der; Schurer, P.J.; Sawatzky, G.A.

    1975-01-01

    A temperature-dependent Moessbauer study was conducted in FeX alloys, where X = Al, Si, Ti, V, Cr, Mn, Co, and Ni, aimed at solving the problem of 'what is localized and what is itinerant in iron ferromagnetism'. The experimental results are interpreted using a phenomenological model based on a modified Zener-Vonsovskij theory. Absorption spectra of FeX alloys were measured as a function of temperature. It was found that the 3d magnetic moments in iron were mainly localized while exchange coupling was provided by partly itinerant 3d electrons. (L.D.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-17

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

  20. Salt Fog Testing Iron-Based Amorphous Alloys

    International Nuclear Information System (INIS)

    Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

    2007-01-01

    Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)