WorldWideScience

Sample records for rare earth magnets

  1. 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...

  2. Rare Earths and Magnetic Refrigeration

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Magnetic refrigeration is a revolutionary, efficient, environmentally friendly cooling technology, which is on the threshold of commercialization. The magnetic rare earth materials are utilized as the magnetic refrigerants in most cooling devices, and for many cooling application the Nd2Fe14B permanent magnets are employed as the source of the magnetic field. The status of the near room temperature magnetic cooling was reviewed.

  3. Magnetic Rare-Earth Superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Gibbs, D.; Böni, P.

    1988-01-01

    The magnetic structures of several single‐crystal, magnetic rare‐earth superlattice systems grown by molecular‐beam epitaxy are reviewed. In particular, the results of recent neutron diffraction investigations of long‐range magnetic order in Gd‐Y, Dy‐Y, Gd‐Dy, and Ho‐Y periodic superlattices...... are presented. In the Gd‐Y system, an antiphase domain structure develops for certain Y layer spacings, whereas modified helical moment configurations are found to occur in the other systems, some of which are commensurate with the chemical superlattice wavelength. References are made to theoretical interaction...

  4. 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.

  5. Non-rare earth magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-09-26

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

  6. Rare earth magnets and impaction.

    Science.gov (United States)

    Vardimon, A D; Graber, T M; Drescher, D; Bourauel, C

    1991-12-01

    Aberration in the eruption process was found to be a prime etiologic factor in inducing impaction. Thus an ideal treatment approach should attempt to mimic the normal eruption modus. However, conventional traction methods have been found to be associated with gingiva inflammation, bone recession, reduced attached gingiva, periodontal pockets, exposed cementoenamel junction, and root resorption of the impacted and adjacent teeth. These side effects are the result of premature exposure of the impacted tooth to the oral cavity through a nonself-cleansing pathway and an uncontrolled force system. The present study introduces a new, magnetic attraction system, with a magnetic bracket bonded to an impacted tooth and an intraoral magnet linked to a Hawley type retainer. Vertical and horizontal magnetic brackets were designed, with the magnetic axis magnetized parallel and perpendicular to the base of the bracket, respectively. The vertical type is used for impacted incisors and canines, and the horizontal magnetic bracket is applied for impacted premolars and molars. A three-dimensional analysis of the magnetic force system, by means of the OMSS apparatus, found the small magnetic bracket combined with a large pole surface area of the intraoral magnet to exhibit the most efficient convergent guidance. For this report the magnetic eruption device was examined on one animal subject and four patients. The Nd2Fe14B magnets were coated with parylene and/or encapsulated in stainless steel housings. In deep impaction, the magnetic bracket was cold-sterilized before surgery, and the surgical mucoperiosteal flap was then sutured over the bonded magnetic bracket. Attraction was initiated 1 to 2 weeks after healing. Thus tooth emergence into the oral cavity replicated normal eruption conditioning. The system operated at an attractive force level of 0.2 to 0.5 N. Adjustment was accomplished by temporarily interposing a magnetic spacer between the two magnetic units. No side effects

  7. Anisotropy of rare-earth magnets

    Institute of Scientific and Technical Information of China (English)

    R.Skomski; D.J.Sellmyer

    2009-01-01

    Rare-earth intermetallics such as Nd2FeI4B and Sm-Co are widely used as high-performance permanent magnets,because they combine high magnetocrystalline anisotropy with reasonable magnetization and Curie temperature.The anisotropy is a combined effect of spin-orbit coupling and electrostatic crystal-field interactions.The main contribution comes from the rare-earth 4f electrons,which are well-screened from the crystalline environment but exhibit a strong spin-orbit coupling.In this limit,the magnetocrystalline anisotropy has a very transparent physical interpretation,the anisotropy energy essentially being equal to the energy of Hund's-rules 4f ion in the crystal field.The corresponding expression for the lowest-order uniaxial anisotropy constant K1 is used to discuss rare-earth substitutions,which have recently attracted renewed interest due to shifts in the rare-earth production and demand.Specific phenomena reviewed in this article are the enhancement of the anisotropy of Sm2Fe17 due to interstitial nitrogen,the use of Sm-Co magnets for high-temperature applications,and the comparison of rare-earth single-ion anisotropy with other single-ion and two-ion mechanisms.

  8. Recovering heavy rare earth metals from magnet scrap

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-08-08

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

  9. Magnetic anisotropies of rare-earth compounds

    Science.gov (United States)

    Loewenhaupt, M.; Rotter, M.; Kramp, S.

    2000-03-01

    There are two kinds of magnetic anisotropy in rare-earth compounds: the single-ion anisotropy caused by the crystal field (CF) and the anisotropy of the two-ion interactions. Both types of anisotropy have to be considered to arrive at a consistent description of the magnetic properties of the orthorhombic intermetallic compound NdCu 2. From the analysis of NdCu 2 we can derive predictions for the type of ordering in other isostructural RCu 2 compounds, that agree well with experimental results: If the magnetic moments point into the crystallographic b-direction, an ordering wave vector of (2/3 0 0) is expected. If the moments are oriented perpendicular to b then the ordering wave vector is (2/3 1 0) .

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

    Science.gov (United States)

    Franczak, Agnieszka; Binnemans, Koen; Jan Fransaer

    2016-10-05

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

  11. 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.

  12. Preparation of Rare-Earth Composite Ferrite Magnetic Fluid

    Institute of Scientific and Technical Information of China (English)

    蒋荣立; 刘永超; 刘守坤; 鞠明礼

    2004-01-01

    Water-based rare-earth ferrite (RexFe3-xO4)magnetic fluids were prepared by chemical co-precipitation method. The result shows that saturation magnetic intensity of ferrite magnetic fluids can be improved by adding Dy3+ and the saturation magnetic intensity will reach the highest if n(Fe)∶n(Dy3+)=30∶1. The modification and formation mechanism of RexFe3-xO4 particles is discussed in detail. The physicochemical properties are investigated by the Gouy magnetic balance, IR, TEM, XRD, and EDX, etc.

  13. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker;

    1970-01-01

    The magnetic field dependence of the energy of long- wavelength magnons in Tb-10%Ho has been studied by inelastic neutron scattering. The results agree with the `frozen-lattice' model, provided that the second-order magnetoelastic effect is taken into account. The planar anisotropy is almost...

  14. Magnetic properties of rare earth superlattices

    CERN Document Server

    Wilkins, C J T

    2001-01-01

    Single-crystal Tm/Y and Tm/Lu superlattices have been grown using molecular beam epitaxy and their chemical structures have been determined using X-ray diffraction. Magnetisation measurements have revealed a more complicated phase diagram than that of pure Tm. Application of a field along the c-direction gave rise to an extra transition, and transitions were detected for the superlattices when the field was applied along the b-axis. In neutron diffraction studies, c-axis longitudinally modulated magnetic structures were found for both Tm/Y and Tm/Lu, which propagate coherently through the non-magnetic layers. In the case of Tm/Lu superlattices, there is evidence for ordering of the basal plane components.

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

    Science.gov (United States)

    Bondemark, L; Kurol, J; Wennberg, A

    1994-11-01

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

  16. Magnetic alignment study of rare-earth-containing liquid crystals.

    Science.gov (United States)

    Galyametdinov, Yury G; Haase, Wolfgang; Goderis, Bart; Moors, Dries; Driesen, Kris; Van Deun, Rik; Binnemans, Koen

    2007-12-20

    The liquid-crystalline rare-earth complexes of the type [Ln(LH)3(DOS)3]-where Ln is Tb, Dy, Ho, Er, Tm, or Yb; LH is the Schiff base N-octadecyl-4-tetradecyloxysalicylaldimine; and DOS is dodecylsulfate-exhibit a smectic A phase. Because of the presence of rare-earth ions with a large magnetic anisotropy, the smectic A phase of these liquid crystals can be easier aligned in an external magnetic field than smectic A phases of conventional liquid crystals. The magnetic anisotropy of the [Ln(LH)3(DOS)3] complexes was determined by measurement of the temperature-dependence of the magnetic susceptibility using a Faraday balance. The highest value for the magnetic anisotropy was found for the dysprosium(III) complex. The magnetic alignment of these liquid crystals was studied by time-resolved synchrotron small-angle X-ray scattering experiments. Depending on the sign of the magnetic anisotropy, the director of the liquid-crystalline molecules was aligned parallel or perpendicular to the magnetic field lines. A positive value of the magnetic anisotropy (and parallel alignment) was found for the thulium(III) and the ytterbium(III) complexes, whereas a negative value of the magnetic anisotropy (and perpendicular alignment) was observed for the terbium(III) and dysprosium(III) complexes.

  17. 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%.

  18. 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.

  19. Magnetization dynamics in rare earth doped NiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Kiessling, Matthias; Woltersdorf, Georg; Back, Christian [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D- 93040 Regensburg (Germany); Thiele, Jan-Ulrich; Schabes, Manfred [Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, CA 95135 (United States)

    2007-07-01

    The influence of rare earth dopants on the damping parameter and the resulting possibility to control this parameter were investigated. In our experiments NiFe films were doped with Dysprosium, Holmium, Terbium, and Gadolinium. The magnetization dynamics of these rare earth doped films was mainly studied by means of ferromagnetic resonance (FMR) and network-analyzer ferromagnetic resonance. It is demonstrated that the doping of a NiFe film by a small amount of rare earth elements (Holmium, Terbium and Dysprosium) greatly effects its magnetic relaxation rate. This additional damping is proportional to the doping level. Compared to the pure NiFe film it is possible to increase the damping parameter of the magnetic film by two orders of magnitude. On the other hand Gadolinium as a dopant has no influence on the damping parameter. For small dopant concentrations the in and out-of-plane FMR measurements at various frequencies can be well described by the same damping parameter. This is expected for the Gilbert damping term in the equation of motion. Therefore the increased damping can be attributed to an increased rate of transfer of angular momentum from the spin system to the lattice.

  20. Magnetic and Magnetoelectric Properties of Rare Earth Molybdates

    Directory of Open Access Journals (Sweden)

    B. K. Ponomarev

    2012-01-01

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

  1. Combinatorial investigation of rare-earth free permanent magnets

    Science.gov (United States)

    Fackler, Sean Wu

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-07

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

  3. Pulsed field magnetization in rare-earth kagome systems

    Science.gov (United States)

    Hoch, M. J. R.; Zhou, H. D.; Mun, E.; Harrison, N.

    2016-02-01

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd3+ is a Kramers ion while Pr3+ is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  4. Pulsed field magnetization in rare-earth kagome systems.

    Science.gov (United States)

    Hoch, M J R; Zhou, H D; Mun, E; Harrison, N

    2016-02-03

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd(3+) is a Kramers ion while Pr(3+) is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  5. The impact of rare earth cobalt permanent magnets on electromechanical device design

    Science.gov (United States)

    Fisher, R. L.; Studer, P. A.

    1979-01-01

    Specific motor designs which employ rare earth cobalt magnets are discussed with special emphasis on their unique properties and magnetic field geometry. In addition to performance improvements and power savings, high reliability devices are attainable. Both the mechanism and systems engineering should be aware of the new performance levels which are currently becoming available as a result of the rare earth cobalt magnets.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  7. 78 FR 42974 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same...

    Science.gov (United States)

    2013-07-18

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same... the sale within the United States after importation of certain sintered rare earth magnets, methods...

  8. 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....

  9. Magnetism of Rare-Earth Compounds with Non-Magnetic Crystal-Field Ground Levels

    Institute of Scientific and Technical Information of China (English)

    LIU Zhao-Sen

    2007-01-01

    @@ Among rare-earth compounds, there are many materials having non-magnetic crystal-field (CF) ground levels.To understand their magnetic behaviour at low temperatures, we study the effects of the CF levels and the Heisenberg-like coupling on the magnetic process of such a crystalline with mean-field and CF theory. It is found that the material can be magnetically ordered if the Heisenberg exchange is sufficiently strong. Additionally we obtain a condition for initial magnetic ordering, and derive a formula for estimating the Curie temperature if the ordering occurs.

  10. Improved Electrical Insulation of Rare Earth Permanent Magnetic Materials With High Magnetic Properties

    Institute of Scientific and Technical Information of China (English)

    CHANG Ying; WANG Da-peng; LI Wei; PAN Wei; YU Xiao-jun; QI Min

    2009-01-01

    Rare earth permanent magnetic materials are typical electrical conductor, and their magnetic properties will decrease because of the eddy current effect, so it is difficult to keep them stable for a long enough time under a high frequency AC field. In the present study, as far as rare earth permanent magnets are concerned, for the first time, rare earth permanent magnets with strong electrical insulation and high magnetic performance have been obtained through experiments, and their properties are as follows:(1) Sm2TM17: Br=0.62 T, jHc=803.7 kA/m, (BH)m= The magnetic properties of Sm2TM17 and NdFeB are obviously higher than those of ferrite permanent magnet, and the electric insulating characteristics of Sm2TM17 and NdFeB applied have in fact been approximately the same as those of ferrite. Therefore, Sm2TM17 and NdFeB will possess the ability to take the place of ferrite under a certain high frequency AC electric field.

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

    Science.gov (United States)

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

    2016-11-23

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

  12. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M.; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J. M. D.; Yu, Ting; Venkatesan, T.

    2016-11-01

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.

  13. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M.; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J. M. D.; Yu, Ting; Venkatesan, T.

    2016-01-01

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications. PMID:27845368

  14. Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study.

    Science.gov (United States)

    Saha, Surajit; Cao, Bing-Chen; Motapothula, M; Cong, Chun-Xiao; Sarkar, Tarapada; Srivastava, Amar; Sarkar, Soumya; Patra, Abhijeet; Ghosh, Siddhartha; Ariando; Coey, J M D; Yu, Ting; Venkatesan, T

    2016-11-15

    Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.

  15. Rare earth metals appliance for magnetic admixtures recovery from mineral premixes

    Directory of Open Access Journals (Sweden)

    A. A. Shevtsov

    2012-01-01

    Full Text Available The analysis of the material composition metallomagnetic admixtures of mineral premix. It is shown that the dressed metallomagnetic impurity includes low-magnetic particles with low magnetic susceptibility. Removing these particles from the product stream in process of magnetic separation using high-energy rare earth magnets is a challenging task.

  16. 77 FR 51046 - Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same; Notice...

    Science.gov (United States)

    2012-08-23

    ... COMMISSION Certain Sintered Rare Earth Magnets, Methods of Making Same and Products Containing Same; Notice... Trade Commission has received a complaint entitled Certain Sintered Rare Earth Magnets, Methods of... United States after importation of certain sintered rare earth magnets, methods of making same...

  17. Troubling Toys: Rare-Earth Magnet Ingestion in Children Causing Bowel Perforations

    Directory of Open Access Journals (Sweden)

    Parkash Mandhan

    2014-01-01

    Full Text Available Ingestion of foreign bodies in the pediatric population is common and magnet ingestion is known to cause a significant morbidity. Rare-earth magnets are small 3–6 mm diameter spherical powerful magnets that are sold as popular desk toys for adults and were previously found in construction toys in attractive colors for children to play with. We describe 2 young healthy children who ingested rare-earth magnets Buckyballs while playing with these magnetic toys and later presented in emergency with acute abdomen. Abdominal imaging revealed several (26 and 5 pieces of rare-earth magnets in the bowel loops. Emergency surgical exploration revealed multiple gastrointestinal perforations and fistula formation at sites of bowel entrapment in between strong magnets apposed to one another. We highlight the potential dangers of rare-earth magnets in children and suggest increasing public awareness about risks involved in rare-earth magnets ingestion by children to overcome this serious public health issue.

  18. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ February, 2010 Rare earth separation plants and downstream producers like NdFeB magnetic materials and phosphor materials successively ceased production due to Spring Festival, Chinese New Year. Transactions in rare earth market were few affected by public holidays.

  19. SUM-RULES FOR MAGNETIC DICHROISM IN RARE-EARTH 4F-PHOTOEMISSION

    NARCIS (Netherlands)

    THOLE, BT; VANDERLAAN, G

    1993-01-01

    We present new sum rules for magnetic dichroism in spin polarized photoemission from partly filled shells which give the expectation values of the orbital and spin magnetic moments and their correlations in the ground state. We apply this to the 4f photoemission of rare earths, where the

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

    Directory of Open Access Journals (Sweden)

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

    2009-01-01

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

  1. 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.

  2. Towards high-performance permanent magnets without rare earths.

    Science.gov (United States)

    Kuz'min, M D; Skokov, K P; Jian, H; Radulov, I; Gutfleisch, O

    2014-02-12

    Achieving a very strong magnetic anisotropy in a 3d material is a difficult, but not an impossible task. It is difficult because there is no general recipe (necessary condition) for a strong anisotropy in a band magnet. Several strategies can be pursued in this situation. One of them is to re-examine the less studied 3d compounds, somewhat neglected since the discovery of the Nd-Fe-B magnets 30 years ago. As an example, a single crystal of (Fe0.7Co0.3)2B has been investigated in this work.

  3. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  4. High-field magnetization of dilute rare earths in yttrium

    DEFF Research Database (Denmark)

    Touborg, P.; Høg, J.; Cock, G. J.;

    1974-01-01

    Magnetization measurements have been performed on single crystals of Y containing small amounts of Tb, Dy, or Er at 4.2 K in fields up to 295 × 105 A/m (370 kOe). Crystal-field and molecular-field parameters obtained from measurements of the initial susceptibility versus temperature give...... a satisfactory quantitative account of the high-field magnetization. This includes characteristic features due to the crossing and mixing of crystal-field levels....

  5. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Rare earth market continued drop tendency.There was not much transaction of didymium oxide and the alloy. Affected by reduced order of NdFeB magnetic materials and inactive dealings of didymium mischmetal,price of didymium mischmetal had dropped from RMB ¥95,000~98,000/ton to RMBY 93,000~95,000/ton currently.

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

    DEFF Research Database (Denmark)

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

    1973-01-01

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

  7. Theory of Magnetic Properties of Heavy Rare Earth Metals:

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Danielsen, O.

    1975-01-01

    dependence is expressed as expansions of thermal averages of the Stevens operators 〈Olm〉. A systematic spin-wave theory, renormalized in the Hartree-Fock approximation, is developed and used to find the temperature dependence of the Stevens operators and the resonance energy in terms of the magnetization...

  8. On the single-ion Magnetic Anisotropy of the Rare-Earth Metals

    DEFF Research Database (Denmark)

    Kolmakova, N.P.; Tishin, A.M.; Bohr, Jakob

    1996-01-01

    The temperature dependences of the single-ion magnetic anisotropy constants for Tb and Dy metals are calculated in terms of the multipole moments of the rare-earth ions utilizing the available crystal-field parameters. The results are compared with the existing experimental data....

  9. Magnetic Order and Spin Dynamics in a Hexagonal Rare Earth Manganite

    Science.gov (United States)

    Helton, J. S.; Singh, D. K.; Elizabeth, S.; Harikrishnan, S.; Lynn, J. W.

    2011-03-01

    Hexagonal rare earth manganites, RMn O3 R = Dy, Ho, Er, Tm, Yb, Lu, Y, or Sc), have attracted a great deal of recent attention as magnetoelectric multiferroics as most of these systems are ferroelectric at room temperature and display magnetic order below TN ~ 100 K. This magnetic order can be quite complex, as both the R and Mn ions lie on geometrically frustrated triangular lattices. DyMn O3 is typically orthorhombic, but can also be grown in the hexagonal phase; Dy 0.5 Y0.5 Mn O3 displays the hexagonal phase and is magnetically diluted at the rare earth site. We have used neutron scattering experiments to explore the magnetic structure and spin dynamics of Dy 0.5 Y0.5 Mn O3 .

  10. Prospects for Non-Rare Earth Permanent Magnets for Traction Motors and Generators

    Science.gov (United States)

    Kramer, M. J.; McCallum, R. W.; Anderson, I. A.; Constantinides, S.

    2012-07-01

    With the advent of high-flux density permanent magnets based on rare earth elements such as neodymium (Nd) in the 1980s, permanent magnet-based electric machines had a clear performance and cost advantage over induction machines when weight and size were factors such as in hybrid electric vehicles and wind turbines. However, the advantages of the permanent magnet-based electric machines may be overshadowed by supply constraints and high prices of their key constituents, rare earth elements, which have seen nearly a 10-fold increase in price in the last 5 years and the imposition of export limits by the major producing country, China, since 2010. We outline the challenges, prospects, and pitfalls for several potential alloys that could replace Nd-based permanent magnets with more abundant and less strategically important elements.

  11. Baotou Rare Earth Became the World’s Biggest High Performance Magnetic Material Base

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>The High Performance Magnetic Material Phase II Project,an industry upgrading project implemented by Inner Mongolia Baotou Iron&Steel Rare Earth(Group)Hi-tech Co.,Ltd,recently basically finished equipment commissioning,signifying that the enterprise had developed the production capacity of15000 t/a Nd-Fe-B strip casting alloy and 5000t/a Nd-Fe-B magnet,thus becoming the world’s

  12. Hyperfine Magnetic Anomaly in the Atomic Spectra of the Rare-Earth Elements

    CERN Document Server

    Gangrsky, Yu P; Karaivanov, D V; Kolesnikov, N N; Marinova, K P; Markov, B N; Rostovsky, V S

    2001-01-01

    The constants of the hyperfine splitting in the atomic optical spectra of the rare-earth elements - Nd, Eu, Gd and Lu - were measured. The method of laser resonance fluorescence in the parallel atomic beam was used. The values of the hyperfine magnetic anomaly were determined from the comparison of magnetic dipole constant ratios of the neighbouring odd Z or N isotopes for the different atomic levels. The connection of these values and the parameters of atomic and nuclear structure is discussed.

  13. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  14. Magnetic structures of R(Cu, Ni)2 compounds (R = heavy rare earth) studied by neutron diffraction

    Science.gov (United States)

    Smetana, Z.; Šíma, V.

    1985-11-01

    Magnetics structures of powdered orthorhombic R(Cu, Ni)2 compounds (R = heavy rare earth) determined by neutron diffraction are described. The influence of magnetocrystalline anisotropy and exchange interactions on the type of magnetic ordering is discussed.

  15. Magnetic Properties of a Rare-Earth Antiferromagnetic Nanoparticle Investigated with a Quantum Simulation Model

    Institute of Scientific and Technical Information of China (English)

    LIU Zhao-Sen; Sechovsk(y) Vladimir; Divi(s) Martin

    2011-01-01

    @@ A Usov-type quantum model based on a mean-field approximation is utilized to simulate the magnetic structure of an assumed rare-earth nanoparticle consisting of an antiferromagnetic core and a paramagnetic outer shell.We study the magnetic properties in the presence and absence of an external magnetic field.Our simulation results show that the magnetic moments in the core region orientate antiferromagnetically in zero external magnetic field; an applied magnetic field rotates all of the magnetic moments in the paramagnetic shell completely to the field direction, and turns those in the core (which tries to maintain its original antiferromagnetic structure) towards the orientation in some degree; and the paramagnetic shell does not have a strong influence on the magnetic configuration of the core.%A Usov-type quantum model based on a mean-field approximation is utilized to simulate the magnetic structure of an assumed rare-earth nanoparticle consisting of an antiferromagnetic core and a paramagnetic outer shell. We study the magnetic properties in the presence and absence of an external magnetic field. Our simulation results show that the magnetic moments in the core region orientate antiferromagnetically in zero external magnetic field; an applied magnetic field rotates all of the magnetic moments in the paramagnetic shell completely to the Geld direction, and turns those in the core (which tries to maintain its original antiferromagnetic structure) towards the orientation in some degree; and the paramagnetic shell does not have a strong influence on the magnetic configuration of the core.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Kohei; Pai, Chi-Feng; Tan, Aik Jun; Mann, Maxwell; Beach, Geoffrey S. D., E-mail: gbeach@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-06-06

    We report the effect of the rare earth metal Gd on current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Pt/Co/Gd heterostructures, characterized using harmonic measurements and spin-torque ferromagnetic resonance (ST-FMR). By varying the Gd metal layer thickness from 0 nm to 8 nm, harmonic measurements reveal a significant enhancement of the effective fields generated from the Slonczewski-like and field-like torques. ST-FMR measurements confirm an enhanced effective spin Hall angle and show a corresponding increase in the magnetic damping constant with increasing Gd thickness. These results suggest that Gd plays an active role in generating SOTs in these heterostructures. Our finding may lead to spin-orbitronics device application such as non-volatile magnetic random access memory, based on rare earth metals.

  17. Electronic and Magnetic Properties of Rare-Earth Metals Doped ZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan

    2015-01-01

    Full Text Available The structural, electronic, and magnetic properties of rare-earth metals doped ZnO monolayer have been investigated using the first-principles calculations. The induced spin polarization is confirmed for Ce, Eu, Gd, and Dy dopings while the induced spin polarization is negligible for Y doping. The localized f states of rare-earth atoms respond to the introduction of a magnetic moment. ZnO monolayer undergoes transition from semiconductor to metal in the presence of Y, Ce, Gd, and Dy doping. More interestingly, Eu doped ZnO monolayer exhibits half-metallic behavior. Our result demonstrates that the RE-doping is an efficient route to modify the magnetic and electronic properties in ZnO monolayer.

  18. Investigation into the magnetic properties of pyrochlore-type rare-earth hafnates

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Jung Hwan; Kremer, Reinhard K.; Lin, Chengtian [MPI for Solid State Research, Stuttgart (Germany)

    2015-07-01

    Cubic rare-earths transition metal pyrochlores with composition R{sub 2}TM{sub 2}O{sub 7} have attracted broad attention because of their unusual magnetic ground state properties related to geometrical frustration of the pyrochlores lattice. So far, the investigation focused mainly on 3d and 4d transition metal systems. The magnetic properties of rare-earths 5d TM pyrochlores are comparatively less well studied. Here we report on the single-crystal growth and the magnetic properties of some rare-earth hafnates (R =Nd, Gd, Dy; TM = Hf) of composition R{sub 2}Hf{sub 2}O{sub 7}. Nd{sub 2}Hf{sub 2}O{sub 7} and Gd{sub 2}Hf{sub 2}O{sub 7} crystallize with the cubic pyrochlores structure whereas diverging reports on the structure of Dy{sub 2}Hf{sub 2}O{sub 7} are available in literature. Crystals of R{sub 2}Hf{sub 2}O{sub 7} have been grown and their structural and magnetic properties have been investigated. Our investigations confirm Nd{sub 2}Hf{sub 2}O{sub 7} and Gd{sub 2}Hf{sub 2}O{sub 7} to crystallize in the cubic pyrochlores structure. Antiferromagnetic ordering below ∝0.5 K has been observed by magnetic susceptibility and heat capacity measurements for both compounds.

  19. Direct Reuse of Rare Earth Permanent Magnets - Wind Turbine Generator Case Study

    DEFF Research Database (Denmark)

    Högberg, Stig; Pedersen, Thomas Stigsberg; Bendixen, Flemming Buus

    2016-01-01

    A novel recycling strategy, direct reuse, for rare earth permanent magnets were investigated in this article. Direct reuse uses small, unit-cell (segmented) magnets to replace the normal solid pole configuration, which is not directly reusable due its unique shape and size. The unit-cell magnets...... output torque, torque ripple, and cogging torque are achievable with this segmentation technique. The influence of the thickness of the adhesive layer was analyzed, and a pole-shaping technique was applied to improve the torque characteristics. The simulation models were verified experimentally...

  20. Direct Reuse of Rare Earth Permanent Magnets - Wind Turbine Generator Case Study

    DEFF Research Database (Denmark)

    Högberg, Stig; Pedersen, Thomas Stigsberg; Bendixen, Flemming Buus;

    2016-01-01

    A novel recycling strategy, direct reuse, for rare earth permanent magnets were investigated in this article. Direct reuse uses small, unit-cell (segmented) magnets to replace the normal solid pole configuration, which is not directly reusable due its unique shape and size. The unit-cell magnets...... are directly reusable due to their standard shape and size, and direct reuse effectively bypasses a number of the expensive and energy intensive processes of normal recycling. Based on a model of a 3 MW direct drive wind turbine generator, the finite element studies concluded that normal values of average...

  1. Magnetic properties of the new rare earth carbide fluoride layered compound: Ho 2CF 2

    Science.gov (United States)

    Kremer, R. K.; Cockcroft, J. K.; Mattausch, Hj.; Raju, N. P.; Simon, A.

    1992-02-01

    We present magnetic susceptibility, specific heat and neutron diffraction data of the new layered rare earth carbide flouride Ho 2CF 2. The susceptibility displays a rounded maximum centered around 4.6 K and a Curie-Weiss law at higher temperatures with a paramagnetic Curie temperature of -4.9(2) K. The specific heat shows a sharp anomaly at 3.61(5) K indicating the onset of long range ordering but also a considerable high temperature tail pointing to low dimensional magnetic behaviour. Low temperature neutron powder diffraction reveals additional magnetic Bragg peaks with significant critical scattering remaining well above the long range ordering temperature.

  2. Anisotropic magnetic exchange in orthorhombic RCu{sub 2} compounds (R=rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Rotter, M. [Technische Univ., Vienna (Austria). Inst. fuer Experimentalphysik; Loewenhaupt, M. [Institut fuer Angewandte Physik, Technische Universitaet Dresden, 01062 Dresden (Germany); Kramp, S. [Institut fuer Angewandte Physik, Technische Universitaet Dresden, 01062 Dresden (Germany); Institut Laue Langevin, BP 156 38042 Grenoble Cedex 9 (France); Reif, T. [Institut fuer Festkoerperforschung, Forschungszentrum Juelich, 52425 Juelich (Germany); Pyka, N.M. [TU Muenchen, Zentrale Betriebseinheit FRM - II, 85747 Garching (Germany); Schmidt, W. [Institut Laue Langevin, BP 156 38042 Grenoble Cedex 9 (France); Kamp, R. van de [Hahn Meitner Institut, 14109 Berlin (Germany)

    2000-03-01

    The magnetic excitations in the field induced ferromagnetic phase F3 of a NdCu{sub 2} single crystal were investigated by means of inelastic neutron scattering experiments. A mean field model using the random phase approximation in connection with anisotropic magnetic bilinear R-R (R denotes a rare earth) exchange interactions is proposed to account for the observed dispersion. The relevance of this model to the analysis of the magnetic ordering process in other RCu{sub 2} compounds is discussed. (orig.)

  3. Development and Application of Rare Earth Permanent Magnet (REPM) Material in Electric Machines

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With the development of permanent materials, the development and application of permanent material electric machine (REPM) have been more mature. At first the state of development and application of REPM electric machine is presented in this paper, many RMEM have been produced in volume such as the pilot exciter used for power set of large-scale thermal power station, the special RMEM synchronous motor for textile, the starter motor for automobile, the brushless permanent magnet DC motor for electric facilities, permanent magnet servomotor for numerical controlled machine tool, rare-earth torque motor, special micro-motor for automobile and so on. Secondly the field of application of REPM electric machine and remaining problems is analyzed, because of the price of the rare-earth permanent magnet materials, the cost of RMEM is currently higher than that of induction machine, on the other side the dispersibility of performance of rare-earth permanent magnet materials and the limitation of technique of integral excitation are also remaining problems, above-mentioned problems handicapped the popularization of REPMEM. At last the developing prospect and trend of REPM electric machines is described, there are four promising types of PMEM: economical type, high performance type, high efficiency and energy-saving type, micromation, intelligibility type. With the appearance of new REPM material and the improvement of its performance and the continuous perfection of performance of electric-power electronic components, the development and the application of REPM electric machines will be further progressed.

  4. Strain-induced modification of magnetic structure and new magnetic phases in rare-earth epitaxial films

    Indian Academy of Sciences (India)

    C Dufour; K Dumesnil; Ph Mangin

    2006-07-01

    Rare earths exhibit complex magnetic phase diagrams resulting from the competition between various contributions to the magnetic energy: exchange, anisotropy and magnetostriction. The epitaxy of a rare-earth film on a substrate induces (i) a clamping to the substrate and (ii) pseudomorphic strains. Both these effects are shown to lead to modifications of the magnetic properties in (0 0 1)Dy, (0 0 1)Tb and (1 1 0)Eu films. In Dy and Tb films, spectacular variations of the Curie temperature have been evidenced. Additionally, Tb films exhibit a new large wavelength magnetic modulation. In Eu films, one of the helical magnetic domains disappears at low temperature whereas the propagation vectors of the other helices are tilted. The link between structural and magnetic properties is underlined via magnetoelastic models. Moreover, molecular beam epitaxy permits the growth of Sm in a metastable dhcp phase. The magnetic structure of dhcp Sm has been elucidated for the first time. In this review, neutron scattering is shown to be a powerful technique to reveal the magnetic structures of rare-earth films.

  5. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    June 20-30 2012 Affected by a sustained slump in the demand from downstream industries, rare earth market remained flat recently. There were not many inquiries for rare earth products in the spot market. Consumers lacked of confidence in the future market. As for the downstream industries, the market of NdFeB magnetic materials and phosphors were in the doldrums. Ceramic, catalyst and polishing powder industries maintained weak. Affected by the global economy, export market of rare earth was weak.

  6. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Rare earth market remained weak recently. Dealings of light and heavy rare earth products were sluggish. Demand for didymium and dysprosium related products was soft and purchasers were not interested in replenishing their stocks. The market of NdFeB magnetic materials and phosphors remained inactive. Meanwhile, ceramic, catalyst and polishing powder industries were weak. Affected by global economical recession, export market of rare earth remained weak.

  7. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Rare earth market was weak recently. There was still no sign of recovery in NdFeB magnetic materials and phosphors market. The market of ceramic, catalyst and polishing powder were in the doldrums. Rare earth deep processing enterprisers hesitated to purchase rare earth products and considered that there was room for further price reduction. Global economy slowed down and there was no sign of improvement yet. The export market was sluggish and transactions were inactive.

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

    Science.gov (United States)

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

    2014-04-01

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

  9. A Report on the Development of Rare Earth-Cobalt Permanent Magnet Technology - Japan.

    Science.gov (United States)

    1981-07-01

    of the rare earth permanent magnets (REPM), gave the opening plenary address in which he reviewed the history of the field and presented a summary of...implantation applications, e.g., for fixing dentures to gums. Initial inhibitory effects on the growth of several standard strains 9 of tumor cells were...axis lattice constant which shows a linear temperature dependence over the whole range. This anomaly is considerably reduced on the partial substitution

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

    Energy Technology Data Exchange (ETDEWEB)

    Cadieu, F.J.

    1992-01-01

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

  11. EU FP7 EREAN training network offers (c)lean recycling solutions for rare-earth magnets

    OpenAIRE

    2015-01-01

    EREAN is the European Rare Earth Magnet Recycling Network which started its activities in September 2013. It trains 15 young researchers in the direct and indirect recycling of NdFeB permanent magnets. The innovative aspect of the EREAN project is that it addresses the whole materials loop from End-of-Life consumer goods to recycling and the production of new REE magnets, with an integrated life cycle assessment. As is highlighted by the European Rare Earths Competency Network (ERECON),...

  12. EU FP7 EREAN training network offers (c)lean recycling solutions for rare-earth magnets

    OpenAIRE

    Binnemans, Koen; Jones, Peter Tom

    2015-01-01

    EREAN is the European Rare Earth Magnet Recycling Network which started its activities in September 2013. It trains 15 young researchers in the direct and indirect recycling of NdFeB permanent magnets. The innovative aspect of the EREAN project is that it addresses the whole materials loop from End-of-Life consumer goods to recycling and the production of new REE magnets, with an integrated life cycle assessment. As is highlighted by the European Rare Earths Competency Network (ERECON),...

  13. 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

  14. Structural, electronic, mechanical and magnetic properties of rare earth nitrides REN (RE= Pm, Eu and Yb)

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, A. [Department of physics, N.M.S.S.V.N college, Madurai, Tamilnadu 625019 (India); Rajeswarapalanichamy, R., E-mail: rrpalanichamy@gmail.com [Department of physics, N.M.S.S.V.N college, Madurai, Tamilnadu 625019 (India); Santhosh, M. [Department of physics, N.M.S.S.V.N college, Madurai, Tamilnadu 625019 (India); Iyakutti, K. [Department of physics and Nanotechnology, SRM University, Chennai, Tamilnadu 603203. India. (India)

    2015-07-01

    The structural, electronic and mechanical properties of rare earth nitrides REN (RE=Pm, Eu and Yb) are investigated in NaCl and CsCl, and zinc blende structures using first principles calculations based on density functional theory. The calculated lattice parameters are in good agreement with the available results. Among the considered structures, these nitrides are most stable in NaCl structure. A pressure induced structural phase transition from NaCl to CsCl phase is observed in all these nitrides. The electronic structure reveals that these rare earth nitrides are half metallic at normal pressure. These nitrides are found to be covalent and ionic in the stable phase. The computed elastic constants indicate that these nitrides are mechanically stable and elastically anisotropic. Our results confirm that these nitrides are ferromagnetic in nature. A ferromagnetic to non-magnetic phase transition is observed at the pressures of 21.5 GPa and 46.1 GPa in PmN and YbN respectively. - Highlights: • Rare earth nitrides PmN, EuN and YbN are found to be ferromagnetic in nature. • Electronic, structural, elastic and mechanical properties of rare earth nitrides are investigated. • A pressure induced structural phase transition is predicted under high pressure. • Electronic structure reveals that these materials exhibit half-metallic behavior. • Computed elastic moduli obey the mechanical stability condition.

  15. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    October 21-31,2012 Recently, dealings of rare earth remained stagnant. Consumers hesitated to increase their stocks for the fear of further decline in rare earth prices. It was difficult for suppliers to sell products and they had reduced quotations to attract buyers. It did not show demand from end users could rebound in short terms. Dealings of rare earth products in spot market were few. The market of NdFeB magnetic materials, phosphors, catalysts, polishing powders and ceramics remained sluggish. There was no sign of picking up in world economy. Export market of rare earths maintained inactive.

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

    Science.gov (United States)

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

    2014-04-01

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

  17. Magnetism and exchange interaction of small rare-earth clusters; Tb as a representative

    CERN Document Server

    Peters, Lars; Sanyal, Biplab; van Dijk, Chris; Bowlan, John; de Heer, Walt; Delin, Anna; Di Marco, Igor; Eriksson, Olle; Katsnelson, Mikhail I; Johansson, Börje; Kirilyuk, Andrei

    2016-01-01

    Here we follow, both experimentally and theoretically, the development of magnetism in Tb clusters from the atomic limit, adding one atom at a time. The exchange interaction is, surprisingly, observed to drastically increase compared to that of bulk, and to exhibit irregular oscillations as a function of the interatomic distance. From electronic structure theory we find that the theoretical magnetic moments oscillate with cluster size in exact agreement with experimental data. Unlike the bulk, the oscillation is not caused by the RKKY mechanism. Instead, the inter-atomic exchange is shown to be driven by a competition between wave-function overlap of the 5d shell and the on-site exchange interaction, which leads to a competition between ferromagnetic double-exchange and antiferromagnetic super-exchange. This understanding opens up new ways to tune the magnetic properties of rare-earth based magnets with nano-sized building blocks.

  18. Composition dependence of the magnetic properties of strontium hexaferrite doped with rare earth ions

    Science.gov (United States)

    Singh, Taminder; Batra, M. S.; Singh, Iqbal; Katoch, Arun

    2014-09-01

    Rare earth substituted ferrite Sr1-xRExFe12O19 (where RE = La, Gd and Dy, x = 0.0, 0.10, 0.20 and 0.30), have been prepared by employing the ceramic technique and subsequent heat treatment. The magnetic properties of the calcined samples were characterized with a Vibrating Sample Magnetometer (VSM). The samples were sintered at 1150°C for 8 hours. The samples were characterized for magnetic properties such as specific saturation magnetization MS, specific remanence magnetization Mr, and coercivity Hc as well as microstructure. It has been observed that all these parameters depend on the composition and heat treatment of the prepared samples. The coercively Hc exhibits an increase as the RE content increases in Sr1-xRExFe12O19 ferrite. With increasing RE content the MS and Mr decrease due to dissolution of RE ion into hexaferrite lattice.

  19. Dense arrays of cobalt nanorods as rare-earth free permanent magnets.

    Science.gov (United States)

    Anagnostopoulou, E; Grindi, B; Lacroix, L-M; Ott, F; Panagiotopoulos, I; Viau, G

    2016-02-21

    We demonstrate in this paper the feasibility to elaborate rare-earth free permanent magnets based on cobalt nanorods assemblies with energy product (BH)max exceeding 150 kJ m(-3). The cobalt rods were prepared by the polyol process and assembled from wet suspensions under a magnetic field. Magnetization loops of dense assemblies with remanence to a saturation of 0.99 and squareness of 0.96 were measured. The almost perfect M(H) loop squareness together with electron microscopy and small angle neutron scattering demonstrate the excellent alignment of the rods within the assemblies. The magnetic volume fraction was carefully measured by coupling magnetic and thermogravimetric analysis and found in the range from 45 to 55%, depending on the rod diameter and the alignment procedure. This allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m(-3) was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets.

  20. Japanese Rare Earth Market

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Since China cancelled export rebate in May this year,prices of magnetic materials related rare earth productscontinuously rose. Increasing production cost is largelyattributed to investment in environmental protectionequipments. Prices of Nd and Dy metals rose 20~30% over thebeginning of this year.Price of Nd was USD 11.5 - 12/Kg from USD 9/Kg at theend of 2004, up 30%. Price of Dy rose to USD 65- 70/Kg fromUSD 50/Kg early this year, up 20%. Price of Pr climbed to USD13.5 - 14/Kg from USD 11/Kg, up 30%. Pri...

  1. Substitution of Nd with other rare earth elements in melt spun Nd2Fe14B magnets

    Directory of Open Access Journals (Sweden)

    D. N. Brown

    2016-05-01

    Full Text Available This is a contemporary study of rapidly quenched Nd1.6X0.4Fe14B magnetic materials (where X= Nd, Y, Ce, La, Pr, Gd and Ho. A 20% substitution of the Nd component from Nd2Fe14B can bring about some commercial advantage. However, there will be some compromise to the magnetic performance. Light rare earth elements are definitely more abundant (Y, Ce, La than the heavier rare earth elements, but when they are included in RE2Fe14B magnets they tend to lower magnetic performance and thermal stability. Substituting heavy rare earth elements (Gd, Ho for Nd in Nd2Fe14B improves the thermal stability of magnets but causes a loss in magnet remanence.

  2. Long-range magnetic order in models for rare-earth quasicrystals

    Science.gov (United States)

    Thiem, Stefanie; Chalker, J. T.

    2015-12-01

    We take a two-step theoretical approach to study magnetism of rare-earth quasicrystals by considering Ising spins on quasiperiodic tilings, coupled via Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. First, we compute RKKY interactions from a tight-binding Hamiltonian defined on the two-dimensional quasiperiodic tilings. We find that the magnetic interactions are frustrated and strongly dependent on the local environment. This results in the formation of clusters with strong bonds at certain patterns of the tilings that repeat quasiperiodically. Second, we examine the statistical mechanics of Ising spins with these RKKY interactions, using extensive Monte Carlo simulations. Although models that have frustrated interactions and lack translational invariance might be expected to display spin-glass behavior, we show that the spin system has a phase transition to low-temperature states with long-range quasiperiodic magnetic order. Additionally, we find that in some of the systems spin clusters can fluctuate much below the ordering temperature.

  3. Crystal field and magnetism with Wannier functions:rare-earth doped aluminum garnets

    Institute of Scientific and Technical Information of China (English)

    Eva Mihóková; Pavel Novák; Valentin V. Laguta

    2015-01-01

    Using the recently developed method we calculated the crystal field parameters in yttrium and lutetium aluminum garnets doped with seven trivalent Kramers rare-earth ions. We then inserted calculated parameters into the atomic-like Hamiltonian taking into account the electron-electron, spin-orbit and Zeeman interactions and determined the multiplet splitting by the crystal field as well as magneticĝ tensors. We compared calculated results with available experimental data. Very good agreement with the spectro-scopic data and qualitative agreement with experimentalĝ tensors was found.

  4. Magnetic properties of rare earth HoCrO3 chromites

    Institute of Scientific and Technical Information of China (English)

    SU Yuling; ZHANG Jincang; FENG Zhenjie; LI Zijiong; SHEN Yan; CAO Shixun

    2011-01-01

    The temperature dependence of the magnetic properties was systemically studied by dc/ac magnetization and specific heat measurement for heavy rare earth HoCrO3 chromites.The results revealed the existence of complex phase coexistence and competitive magnetic behavior in HoCrO3 chromites.It was found that,in the region of higher temperature above 141.0 K,HoCrO3 behaved as a typical Cufie-Weiss paramagnetic (PM).And in the region of low temperature,a novel magnetization behavior was observed with negative magnetization (diamagnetism-like) characteristics under an external field of 100 Oe and M-Tcurves exhibited two symmetrical branches for field cooling (FC) and zero field cooling (ZFC) modes.This behavior indicated the coexistence of canted antiferromagnetic (CAFM) and weak ferromagnetic (FM) phase.These also exhibited the existence of competition mechanism below characteristic temperature TN1=141.0 K and the magnetic order of Ho ion below 7.5 K.The current complex magnetization might be attributed to the interaction between paramagnetic Ho3+moments and canted Cr3+ moments.

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

    Science.gov (United States)

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

    2016-12-22

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

  6. Identification and recovery of rare-earth permanent magnets from waste electrical and electronic equipment.

    Science.gov (United States)

    Lixandru, A; Venkatesan, P; Jönsson, C; Poenaru, I; Hall, B; Yang, Y; Walton, A; Güth, K; Gauß, R; Gutfleisch, O

    2017-10-01

    Nd-Fe-B permanent magnets are a strategic material for a number of emerging technologies. They are a key component in the most energy efficient electric motors and generators, thus, they are vital for energy technologies, industrial applications and automation, and future forms of mobility. Rare earth elements (REEs) such as neodymium, dysprosium and praseodymium are also found in waste electrical and electronic equipment (WEEE) in volumes that grow with the technological evolution, and are marked as critical elements by the European Commission due to their high economic importance combined with significant supply risks. Recycling could be a good approach to compensate for the lack of rare earths (REs) on the market. However, less than 1% of REs are currently being recycled, mainly because of non-existing collection logistics, lack of information about the quantity of RE materials available for recycling and recycling-unfriendly product designs. To improve these lack of information, different waste streams of electrical and electronic equipment from an industrial recycling plant were analyzed in order to localize, identify and collect RE permanent magnets of the Nd-Fe-B type. This particular type of magnets were mainly found in hard disk drives (HDDs) from laptops and desktop computers, as well as in loudspeakers from compact products such as flat screen TVs, PC screens, and laptops. Since HDDs have been investigated thoroughly by many authors, this study focusses on other potential Nd-Fe-B resources in electronic waste. The study includes a systematic survey of the chemical composition of the Nd-Fe-B magnets found in the selected waste streams, which illustrates the evolution of the Nd-Fe-B alloys over the years. The study also provides an overview over the types of magnets integrated in different waste electric and electronic equipment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. 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.

  8. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market remained stagnant recently. The buyers did not show willingness to replenish raw materials affected by weak demand. Most persons in rare earth circle were not confident with the short-term rare earth market. Demand for didymium mischmetal was soft recently. The market of dysprosium related products was quiet and NdFeB magnet producers were inactive in the purchase. Phosphor market was stagnant as well. Buyers were cautious on replenishing the material. There were few inquiries for europium oxide (99.9%) in spot market and transactions were difficult.

  9. Structural and magnetic properties of epitaxial Pr-Co films with varying rare-earth content

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Ajit K.; Neu, Volker [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden (Germany); Institute for Physics of Solids, Department of Physics, Dresden University of Technology, 01062 Dresden (Germany); Faehler, Sebastian; Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden (Germany); Groetzschel, Rainer [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Rossendorf (Germany); Bedanta, Subhankar; Kleemann, Wolfgang [Angewandte Physik, Universitaet Duisburg-Essen (Germany)

    2007-07-01

    Pulsed laser deposited epitaxial Pr{sub x}Co{sub 100-x} (x=8.7 to 27.6 at.%) thin films were systematically studied as a function of Pr content. Structural and magnetic measurements reveal different phases for specific composition range and in some cases the phases observed are in contrast to their bulk counterpart. Uniaxial anisotropy at room temperature is observed in all the films enabling excellent hard magnetic properties. For the optimum combination of coercivity and polarization, the measured (BH) max reaches values of 310 kJ/m{sup 3}, which exceeds the highest energy product value reported for RE-Co (RE=Rare Earth) systems. Temperature dependent ac susceptibilty measurements reveal that films x=8.7 to 20.4 undergo a spin reorientation from easy axis to easy cone, but films with x=22.9 to 27.6 maintain their uniaxial anisotropy throughout the temperature range of investigation.

  10. Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

    Science.gov (United States)

    Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

    2014-06-17

    In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

  11. Magnetic-field-induced valence transition in rare-earth systems

    Indian Academy of Sciences (India)

    G Gangadhar Reddy; A Ramakanth; S K Ghatak

    2002-05-01

    The magnetic-field-induced valence transition in rare-earth systems has been investigated using the periodic Anderson model supplemented by the Falicov–Kimball term. This model has been solved by first decoupling the Falicov–Kimball term as proposed by Khomskii and Koharjan and then taking the limit of infinite intra-site Coulomb repulsion. The valence transition both in the absence and in the presence of magnetic field as a function of temperature is studied. It has been found that the system makes transition from non-magnetic to magnetic state when the magnetic field increases beyond a critical value c. The phase boundary defined in terms of reduced field c()/c(0) and reduced temperature /v (v being the valence transition temperature in the absence of field) is almost independent of the position of the localized level. The results are in qualitative agreement with experimental observations in Yb- and Eu-compounds.

  12. Electronic structures and magnetic properties of rare-earth-atom-doped BNNTs

    Science.gov (United States)

    Ren, Juan; Zhang, Ning-Chao; Wang, Peng; Ning, Chao; Zhang, Hong; Peng, Xiao-Juan

    2016-04-01

    Stable geometries, electronic structures, and magnetic properties of (8,0) and (4,4) single-walled BN nanotubes (BNNTs) doped with rare-earth (RE) atoms are investigated using the first-principles pseudopotential plane wave method with density functional theory (DFT). The results show that these RE atoms can be effectively doped in BNNTs with favorable energies. Because of the curvature effect, the values of binding energy for RE-atom-doped (4,4) BNNTs are larger than those of the same atoms on (8,0) BNNTs. Electron transfer between RE-5 d, 6 s, and B-2 p, N-2 p orbitals was also observed. Furthermore, electronic structures and magnetic properties of BNNTs can be modified by such doping. The results show that the adsorption of Ce, Pm, Sm, and Eu atoms can induce magnetization, while no magnetism is observed when BNNTs are doped with La. These results are useful for spintronics applications and for developing magnetic nanostructures.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-15

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

  14. Calculations of magnetic x-ray dichroism in the 3d absorption spectra of rare-earth compounds

    NARCIS (Netherlands)

    GOEDKOOP, JB; THOLE, BT; VANDERLAAN, G; SAWATZKY, GA; DEGROOT, FMF; FUGGLE, JC; de Groot, Frank

    1988-01-01

    We present atomic calculations for the recently discovered magnetic x-ray dichroism (MXD) displayed by the 3d x-ray-absorption spectra of rare-earth compounds. The spectral shapes expected at T=0 K for linear polarization parallel and normal to the local magnetic field is given, together with the te

  15. {sup 57}Fe Moessbauer spectroscopy applied to the study of rare-earth iron permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Persiano, A.I.C. [Departamento de Fisica-UFMG (Brazil)], E-mail: persiano@fisica.ufmg.br

    1999-11-15

    A survey of some important applications of {sup 57}Fe Moessbauer spectroscopy to the study of local magnetic and structural characteristics of the main phases in the rare-earth-transition metal (RE-TM) class of materials used in the development of the new generations of high performance permanent magnets is presented. A brief history of the hard magnets evolution in the last decades is followed by the description and interpretation of the main effects on the hyperfine interactions revealed by the Moessbauer technique. The contribution of the distinct crystallographic iron sites to the saturation magnetization of the rare-earth iron compounds is discussed in terms of the corresponding types of magnetic coupling, based mainly on the iron-iron distances, the number of iron neighbors and the respective hyperfine fields. These features are inferred from the energy of the resonant absorption by the iron sites 4e/4c/8j{sub 1}/8j{sub 2}/16k{sub 1}/16k{sub 2} in the Nd{sub 2}Fe{sub 14}B, sites 6c/9d/18f/18h in the light RE{sub 2}Fe{sub 17}N{sub 3} and 8f/8i/8j in the RE(Fe{sub 12-x}TM{sub x}) phases. The direction of the easy axis of magnetization is discussed taking into account the effects due to the interaction between the local magnetization vector and the electric field gradients. Some other characteristics such as the occupancy of the TM atoms in the 1 : 12 compounds as well as in some hybrid (Fe +TM) 2 : 17 structures are also discussed in terms of the changes in the relative subspectral areas. The effects regarding charge transfers and lattice expansions due to the incorporation of nitrogen and also of other different interstitial elements to the 2 : 17 rhombohedral structure are discussed considering the relative changes of the isomer shifts in comparison with the alterations in the parameter due exclusively to the respective volume expansions.

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

    Directory of Open Access Journals (Sweden)

    Ryo Sasai

    2016-06-01

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

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

    DEFF Research Database (Denmark)

    Szpunar, B.; Lindgård, Per-Anker

    1977-01-01

    It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures for Gdl-xTx (T = Co, Ni, and Fe) and Y1-xCox can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition-metal pseudo-spin......1-xCox durch ein einfaches Model1 erklärt werden können, das eine RKKY-Wechsel-wirkung zwischen den Momenten der Seltenen Erden und des Pseudo-Spins des Übergangsmetalls annimmt. Die Wechselwirkung wird durch ein effektives Legierungsmedium übermittelt, das mit der CPA-Theorie und elliptischen...

  18. Radiation Field Forming for Industrial Electron Accelerators Using Rare-Earth Magnetic Materials

    Science.gov (United States)

    Ermakov, A. N.; Khankin, V. V.; Shvedunov, N. V.; Shvedunov, V. I.; Yurov, D. S.

    2016-09-01

    The article describes the radiation field forming system for industrial electron accelerators, which would have uniform distribution of linear charge density at the surface of an item being irradiated perpendicular to the direction of its motion. Its main element is non-linear quadrupole lens made with the use of rare-earth magnetic materials. The proposed system has a number of advantages over traditional beam scanning systems that use electromagnets, including easier product irradiation planning, lower instantaneous local dose rate, smaller size, lower cost. Provided are the calculation results for a 10 MeV industrial electron accelerator, as well as measurement results for current distribution in the prototype build based on calculations.

  19. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ July 20~31 Rare earth market still went downward, which was mainly led by sluggish demand for didymium products. Weak demand by domestic NdFeB market was attributed to continuous price falling of didymium mischmetal.

  20. Investigation of structural, magnetic and optical properties of rare earth substituted bismuth ferrite

    Institute of Scientific and Technical Information of China (English)

    T.Durga Rao; T.Karthik; Saket Asthana

    2013-01-01

    Polycrystalline BiFeO3 and rare earth substituted Bi0.9R0.1FeO3 (BRFO,R=Y,Ho and Er) compounds were prepared by rapid solid state sintering technique.Structural phase analysis indicated that all the compounds stabilized in rhombohedral structure (R3c space group) and a small orthorhombic phase fraction was observed in BRFO compounds.From the Raman spectra results,the changes in the phonon frequencies (A1) and line widths suggested lattice distortion in the BRFO compounds as was evidenced in the XRD analysis.Compared to the linear variation of magnetization with magnetic field (M-H) shown by BFO,an obvious M-H loop was observed in BRFO compounds which could be due to the suppression of space modulated spin structure and was explained on the basis of weak ferromagnetism and field induced spin reorientation.UV-Vis spectroscopy evidenced a change in local FeO6 environment due to shift in the 6A1g→4T2g energy transition band.BRFO compounds with improved remnant magnetization and coercive field are applicable for magnetoelectric devices.

  1. Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

    Science.gov (United States)

    Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

    2015-08-18

    The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

  2. Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare Earth Elements

    Science.gov (United States)

    Polido Legaria, Elizabeth; Rocha, Joao; Tai, Cheuk-Wai; Kessler, Vadim G.; Seisenbaeva, Gulaim A.

    2017-03-01

    Due to the increasing demand of Rare Earth Elements (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO2 and highly stable γ-Fe2O3-SiO2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE3+/g vs. 40 mg RE3+/g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and 13C and 29Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.

  3. The many faces of order-by-disorder in rare-earth pyrochlore magnets

    Science.gov (United States)

    Gingras, Michel J. P.

    Order-by-disorder (ObD) is a concept of central importance in the field of frustrated magnetism. Saddled with large accidental degeneracies, a subset of states, those that support the largest quantum and/or thermal fluctuations, may be selected to form true long-range order. More formally, one often begins describing a system in terms of some order parameter m with the low-energy description framed in terms of an effective action Γ (m) . In each ObD scenario, one starts from an artificial limit where there is an accidental degeneracy; that is the effective action at this point, Γ0 (m) , has an accidental symmetry. One may then view ObD phenomena as cases where the corrections to Γ0 (m) arise through some form of fluctuation corrections, may they be thermal, quantum or virtual, towards an enlarged higher energy Hilbert space. In the rare-earth pyrochlore oxides, of formula R2M2O7, the trivalent magnetic rare-earth ions R3+ (e.g R = Gd, Er, Yb; M = Ti, Sn is non-magnetic) reside on a three-dimensional pyrochlore lattice of corner-sharing tetrahedra. This architecture is prone to a high degree of magnetic frustration, with the R2M2 O7 pyrochlore materials having been found over the past twenty years to display a gamut of exotic phenomena. In this talk, I will discuss three such phenomena: (i) the intermediate partially-ordered multiple- k state between 0 . 7 K and 1K in the Gd2Ti2O7 Heisenberg antiferromagnet, (ii) the ordered ψ2 state selection in the XY Er2Ti2O7 antiferromagnet and (iii) the puzzling high sample sensitivity of the Yb2Ti2O7 ``quantum spin ice'' candidate. I will argue that in all three cases, some form of fluctuation corrections to their simplest Γ0 (m) description play a significant role in the state selection and experimentally observed behaviors.

  4. 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

  5. Magneto-optical Kerr effect of magnetic and superconducting rare-earth compounds

    Science.gov (United States)

    Schoenes, J.

    1993-01-01

    Recent magneto-optical investigations of exotic rare-earth compounds, such as reduced-moment magnets and magnetic superconductors, are critically reviewed. Representatives of the first class are cerium compounds like CeSb and CeRh3B2. The former material has attracted particular theoretical attention due to its record Kerr rotation of 14°. CeRh3B2 raised the question, whether a Curie temperature of 115 K can originate from reduced Ce moments. A line shape analysis of the magneto-optical spectra shows that Ce, indeed, is responsible for the moment in CeRh3B2 and it allows to specify the nature of its ground state. Representatives of the second class are Chevrel phases containing Eu2+ ions. The characteristic magneto-optical spectrum of this ion has been identified in various Eu1-xPbxMo6S8 and Eu1-xSnxMo6S8-y Sey Chevrel phases. The temperature and field dependence of the Kerr rotation allow a study of the evolution of the spin polarization of the 4f7 state in the normal, superconducting and field-induced superconducting state.

  6. Effect of Coulomb interaction on the X-ray magnetic circular dichroism spin sum rule in rare earths

    NARCIS (Netherlands)

    Teramura, Y; Tanaka, A; Thole, BT; Jo, T

    A deviation from the spin sum rule, which relates the integrated intensity of the X-ray magnetic circular dichroism (MCD) signal to the expectation value of the spin operator S-z ((S-z)), is numerically calculated in the case of the 3d --> 4f absorption for rare earths from the trivalent Ce to Tm.

  7. Magnetic nanosized rare earth iron garnets R3Fe5O12: Sol-gel fabrication, characterization and reinspection

    Science.gov (United States)

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

    2017-01-01

    The magnetic nanosized rare earth iron garnets (R3Fe5O12, 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.

  8. Development of Strip Casting Technology in Rare Earth Permanent Magnet Alloys and Hydrogen Storage Alloys in China

    Institute of Scientific and Technical Information of China (English)

    Han Weiping; Guo Binglin; Yu Xiaojun; Zhu Jinghan; Cheng Xinghua

    2007-01-01

    The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in rare earth permanent magnet alloys and hydrogen storage alloys were analyzed integrative, on the basis of summary of SC technique development in this paper. The paper mainly includes development history of SC technology, effect of SC technology on alloy microstructure, application of SC technology in RE storage hydrogen alloy and sintered Nd-Fe-B alloy, development of SC equipment and SC product industry. At the same time, the paper points out the existing problem of SC products.

  9. 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.

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

    Science.gov (United States)

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

    2010-07-14

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

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

    NARCIS (Netherlands)

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

    2010-01-01

    The experimental temperature dependence (T = 2-300 K) of single crystal bulk and site susceptibilities of rare earth titanate pyrochlores R2Ti2O7 (R = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) is analyzed in the framework of crystal field theory and a mean field approximation. Analytical expressions for the s

  12. 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.

  13. 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.

  14. Deep X-Ray Lithography Based Fabrication of Rare-Earth Based Permanent Magnets and their Applications to Microactuators

    Energy Technology Data Exchange (ETDEWEB)

    Christenson, T.R.; Garino, T.J.; Venturini, E.L.

    1999-01-27

    Precision high aspect-ratio micro molds constructed by deep x-ray lithography have been used to batch fabricate accurately shaped bonded rare-earth based permanent magnets with features as small as 5 microns and thicknesses up to 500 microns. Maximum energy products of up to 8 MGOe have been achieved with a 20%/vol. epoxy bonded melt-spun isotropic Nd2Fe14b powder composite. Using individually processed sub- millimeter permanent sections multipole rotors have been assembled. Despite the fact that these permanent magnet structures are small, their magnetic field producing capability remains the same as at any scale. Combining permanent magnet structures with soft magnetic materials and micro-coils makes possible new and more efficient magnetic microdevices.

  15. CURRENT SITUATION AND PROSPECTS OF PRODUCTION AND RESERVES OF PERMANENT MAGNETS OF RARE EARTHS: BRAZIL × WORLD

    Directory of Open Access Journals (Sweden)

    Franciele Weschenfelder

    2012-12-01

    Full Text Available Generating energy from renewable sources is not an easy task since it requires different types of technologies, which can add much cost to the system. For this reason, investment in research in this area can be an alternative for economic feasibility of wind power plants, for example. One line of research in this area is the study of new materials such as permanent magnets, with even better properties. These magnets, when used in wind generators add many advantages in the operation there of, and a high torque/volume. For this application it is necessary that these magnets have high coercive field (Hc and high remanent induction (Br. Brazil still has no competition in the industry of permanent magnets, so many studies by government and private enterprise are under development in the country. There is a special focus to the Rare Earths Magnets, the primary raw material for production of permanent magnets.

  16. Dependence of Magnetic Properties of Rapidly Quenching (Nd,Pr)x(FeCoZr)94-xB6 Bonded Magnets on Rare Earths Content

    Institute of Scientific and Technical Information of China (English)

    查五生; 刘颖; 高升吉; 连利仙; 涂铭旌

    2004-01-01

    By using sub-overquenching and annealing method which has a wide processing window, (Nd, Pr)x(FeCoZr)94-xB6 (x=12, 10.5, 10, 9) bonded magnets were prepared and the effect of rare earths content on magnetic properties was investigated. Being spun at sub-overquenching speed the as-spun ribbons consist of amorphous phases mixed with fine crystallites. After crystallization under optimum annealing conditions and bonded with 3.25% (mass fraction) epoxy, the magnets obtained the optimum magnetic properties. The rare earths content directly determines the magnetic properties. With the reduction of rare earths content, Br increases but Hci and (BH)max decrease. x=10 is the critical value for the magnetic properties change. Below this value, Br increases slowly meanwhile Hci and (BH)max decrease strongly because alloy contains extra fractions of soft magnetic phase which are not coupled with the hard magnetic phase. This experimental result is consistent with the calculated results using the model of volume fraction of soft magnetic phase coupled completely suggested.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cadieu, F.J.

    1992-08-01

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

  18. Effect of spacer layer on the magnetization dynamics of permalloy/rare-earth/permalloy trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chen, E-mail: ronanluochen@gmail.com; Yin, Yuli; Zhang, Dong; Jiang, Sheng; Yue, Jinjin; Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); Du, Jun; Zhai, Hongru [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-05-07

    The permalloy/rare-earth/permalloy trilayers with different types (Gd and Nd) and thicknesses of spacer layer are investigated using frequency dependence of ferromagnetic resonance (FMR) measurements at room temperature, which shows different behaviors with different rare earth spacer layers. By fitting the frequency dependence of the FMR resonance field and linewidth, we find that the in-plane uniaxial anisotropy retains its value for all samples, the perpendicular anisotropy remains almost unchanged for different thickness of Gd layer but the values are tailored by different thicknesses of Nd layer. The Gilbert damping is almost unchanged with different thicknesses of Gd; however, the Gilbert damping is significantly enhanced from 8.4×10{sup −3} to 20.1×10{sup −3} with 6 nm of Nd and then flatten out when the Nd thickness rises above 6 nm.

  19. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Active demands from downstream industry drove the price rise of rare earth products in Chinese domestic marketrecently, particularly didymium and dysprosium products. Prices of other rare earth products remained stable.

  20. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market fluctuated slightly recently and the transactions remained sluggish. Environment control was strengthened in southern China and many rare earth plants had gone out of production. Some traders were considering selling commodities at low p

  1. Hunan Rare Earth Group Approved

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Following Guangdong,Guangxi,Fujian and Jiangxi,Hunan announced that it would consolidate its rare earth resources-the consolidation plan of Hunan Rare Earth Group has been approved. Consolidation of the rare earth industry of south China is in full swing.According to "Several Opinions of the State Council on Promoting the Sustainable and Healthy Development of Rare Earth Industry"(hereinafter referred to as "Several Opinions")released in 2011,

  2. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    September 20-30, 2011 Rare earth market remained steady recently. Quoted prices of didymium products by separation and smelting plants kept stable. Some rare earth industrial zones in Baotou, Sichuan and Ganzhou had suspended production with the intensified environmental protection control and consolidation of rare earth industry. Persons in the industry hold a positive attitude toward the rare earth market after the National Day' s holiday in China. The market will develop healthily and orderly in the future.

  3. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Supply of rare earth concentrate remained tight recently. Rare earth market exhibited rising tendency holistically Affected by tight supply of rare earth concentrate, many plants were operated under the capacity. Supply of didymium oxide got tighter and the price was on rising.

  4. Review on Rare Earth/Polymer Composite

    Institute of Scientific and Technical Information of China (English)

    刘力; 张立群; 赵素合; 金日光; 刘美琳

    2002-01-01

    The special properties of rare earth/polymer composite were described. More emph asis was put on the radiation shielding and magnetic properties. In the applicat ion to X-ray shielding, rare earth/polymer composite can make up the feeble abs o rbing area. If the rare earth content is high enough, it can demonstrate strong ability for thermal neutron absorption; The composite has strong paramagnetism. The feasibility of preparing magnetic rare earth/polymer composite was discussed . In addition, three preparation methods were introduced: simple polymerization, mixing and reaction processing. The effect of the rare earth/polymer composites pre -sturcture and the coordinate number of rare earth ions on the light property w as a nalyzed. Rare earth/polymer composite may have the structure and property simlar to those of the ionomer. The feasibility of the in-situ preparation of the rare earth/polymer nano structure is indicated. Besides, the relationship betwe en structure and properties of the rare earth/polymer composite was discussed. T he problems associated with such composite materials were also presented.

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

    Science.gov (United States)

    Ling-Wei, Li

    2016-03-01

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

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

    Science.gov (United States)

    Hammoud, Y.; Parlebas, J. C.

    1991-05-01

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

  7. Rare earth elements in nuclear medicine

    OpenAIRE

    Kodina G.E.; Kulakov V.N.; Sheino I.N.

    2014-01-01

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

  8. Rare earth elements in nuclear medicine

    Directory of Open Access Journals (Sweden)

    Kodina G.E.

    2014-12-01

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

  9. Rare Earth: Production, Trade and Demand

    Institute of Scientific and Technical Information of China (English)

    HONG Feng

    2007-01-01

    @@ Editor's note: The paper was quoted from the papers collection of the "19th International Workshop on Rare Earth Permanent Magnets & Their Applications", held in Beijing on August 30-Spetember 2 of 2006.

  10. Magnetic structure and bonding of rare-earth diboride compounds RB{sub 2}: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kacimi, S.; Zazoua, F.; Djermouni, M.; Zaoui, A. [Modelling and Simulation in Materials Science Laboratory, Djillali Liabes University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Bekkouche, B. [Signals and Systems Laboratory, Abdelhamid Ibn Badis University of Mostaganem, Mostaganem 27000 (Algeria); Boukortt, A. [Elaboration Characterization Physico-Mechanics of Materials and Metallurgical Laboratory ECP3M, Faculty of Sciences and Technology, Abdelhamid Ibn Badis University of Mostaganem, Mostaganem 27000 (Algeria)

    2012-07-15

    The electronic structure and magnetic behavior of hexagonal rare-earth diboride RB{sub 2} are studied using ab initio density-functional theory in the DFT + U approach. The effect of the spin-orbit coupling is also investigated and it is found to be a necessary requirement for the accurate description of the magnetic moment. In this paper, we study the magnetic phase stability of RB{sub 2} compounds; the band structure and the density of state (DOS) results prove that the coulomb potential and the spin-orbit interaction are keys factors to understand the magnetic properties of these series of materials. In addition, we also explain the behavior of a chemical bond of RB{sub 2} compounds through the analysis of the DOS and of the charge density. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Science.gov (United States)

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

    2016-07-22

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

  12. Formation cause,composition analysis and comprehensive utilization of rare earth solid wastes

    Institute of Scientific and Technical Information of China (English)

    许涛; 彭会清

    2009-01-01

    Based on practical situation of rare earth industrial chain,production process and rare earth materials that could produce solid wastes on batch were discussed.Formation cause,formation volume,composition analysis and comprehensive utilization of the solid wastes of rare earth hydrometallurgy slag,electrolysis slag,Fe-based rare earth permanent magnetic materials,Co-based rare earth permanent magnetic materials,rare earth hydrogen storage materials,rare earth polishing powders and rare earth catalysts were ...

  13. Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3

    Science.gov (United States)

    Veverka, Pavel; Kaman, Ondřej; Knížek, Karel; Novák, Pavel; Maryško, Miroslav; Jirák, Zdeněk

    2017-01-01

    Rare-earth-doped ferromagnetic manganites La0.63RE0.07Sr0.30MnO3 (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd3+ ions, whereas Kramers ions Dy3+ and non-Kramers ions Ho3+ contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb3+ is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb3+ doping leads also to a notably increased coercivity compared to other La0.63RE0.07Sr0.30MnO3 systems.

  14. 国外稀土永磁最新动向%Recent Trend of Rare-earth Magnet

    Institute of Scientific and Technical Information of China (English)

    王焰; 潘伟

    2011-01-01

    The technical innovation in energy saving is carried on all over the world,with the emphasis on permanent-magnet rotation machine, leading to great increasement of rare-earth magnet output.The recent trend of research on sintered Nd-Fe-B magnet with high energy products are reviewed in this paper.The mechanism of coercive force are introduced.%为了防止地球变暖,各国正在开发和普及能源革新技术,促使旋转机械的稀土永磁用量迅速增长,超过在VCM等电子信息工业的用量,跃居首位.本文概述了高性能稀土永磁最新动向,介绍了一些关于矫顽力机制的论点.

  15. Magnetic properties and electronic structures of R-Ni-B compounds where R is a heavy rare earth

    Energy Technology Data Exchange (ETDEWEB)

    Burzo, E; Bucur, N; Rednic, V [Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca (Romania); Chioncel, L [Institute of Theoretical Physics, Graz University of Technology, A-8010 Graz (Austria)

    2008-07-09

    Magnetic measurements were performed in the temperature range 4.2-300 K and fields up to 70 kOe on R{sub 3}Ni{sub 7}B{sub 2} compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie-Weiss type behaviour. Effective nickel moments of 1.33 {+-} 0.25 {mu}{sub B} were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.

  16. Magnetic properties and electronic structures of R Ni B compounds where R is a heavy rare earth

    Science.gov (United States)

    Burzo, E.; Bucur, N.; Chioncel, L.; Rednic, V.

    2008-07-01

    Magnetic measurements were performed in the temperature range 4.2-300 K and fields up to 70 kOe on R3Ni7B2 compounds with R = Gd, Tb, Dy, Ho, Er. The Curie temperatures decrease from 38.5 K (Gd) to 7 K (Er). Band structure calculations show that nickel, at 0 K, has a very small magnetic polarization, oriented antiparallel to the rare-earth moment. The XPS measurements suggest the presence of unoccupied Ni3d states. The reciprocal susceptibilities follow a Curie-Weiss type behaviour. Effective nickel moments of 1.33 ± 0.25 µB were determined. The magnetic behaviour of nickel is analysed in models which take into account electron correlation effects in d bands.

  17. Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

    Science.gov (United States)

    Rahbar, Mona; Shannon, Lesley; Gray, Bonnie L.

    2016-05-01

    We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min-1 for pressures up to 9.65 kPa in microfluidic channels 200 μm wide and 200 μm deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min-1 with larger microfluidic channels of up to 1 mm wide and 500 μm deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices.

  18. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Rare earth market was relatively stable recently. There was not much change to the quotations by suppliers. Inquiries for most products increased in spot market and so did to the transactions. Recently, rare earth special invoices attracted the attention in the industry again. It is likely to result in price rise of many rare earth products if the special invoice system can put into effect in the near term.

  19. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    November 1-10, 2012 Some key rare earth producers had paused production since the last ten day period of October in order to retain normal production and market order and stabilize rare earth prices. The production suspension measure by the plants together with severe cracking down on illegal mining by the government had some influence on sluggish market recently. Data showed rapid price increase of major rare earth products after sharp decline previously.

  20. A rare-earth-magnet ion trap for confining low-Z, bare nuclei

    Science.gov (United States)

    Brewer, Samuel M.; Tan, Joseph N.

    2009-05-01

    Simplifications in the theory for Rydberg states of hydrogenlike ions allow a substantial improvement in the accuracy of predicted levels, which can yield information on the values of fundamental constants and test theory if they can be compared with precision frequency measurements.[1] We consider the trapping of bare nuclei (fully-stripped) to be used in making Rydberg states of one-electron ions with atomic number 1earth permanent magnets, and to model the capture of charge-state-selected ions extracted from an electron beam ion trap (EBIT). An experimental apparatus adapted to the NIST EBIT will also be discussed. Reference: [1] U.D. Jentschura, P.J. Mohr, J.N. Tan, and B.J. Wundt, ``Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions,'' Phys. Rev. Lett. 100, 160404 (2008).

  1. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market remained sluggish and quiet holistically recently. Didymium-related market was quiet and the consumers were hesitating in replenishing their inventories. Inquiries for dysprosium-related products were few and the transactions were inactive, Demand for europium oxide (99.99%) was weak and the trade was far from brisk. Baogang Rare Earth suspended production, which has a positive effect in stabilizing the whole rare earth market. But prices of rare earth products did not go up rapidly. This means there were still large inventories in the market.

  2. Magnetic, dielectric and microwave absorption properties of rare earth doped Ni-Co and Ni-Co-Zn spinel ferrites

    Science.gov (United States)

    Stergiou, Charalampos

    2017-03-01

    In this article we analyze the electromagnetic properties of rare earth substituted Ni-Co and Ni-Co-Zn cubic ferrites in the microwave band, along with their performance as microwave absorbing materials. Ceramic samples with compositions Ni0.5Co0.5Fe2-xRxO4 and Ni0.25Co0.5Zn0.25Fe2-xRxO4 (R=Y and La, x=0, 0.02), fabricated with the solid state reaction method, were characterized with regard to the complex permeability μ*(f) and permittivity ε*(f) up to 20 GHz. The rare earth substitutions basically affect the microwave μ*(f) spectra and the dynamic magnetization mechanisms of domain wall motion and magnetization rotation. Key parameters for this effect are the reduced magnetocrystalline anisotropy and the created crystal inhomogeneities. Moreover, permittivity is increased with the Y and La content, due to the enhancement of the dielectric orientation polarization. Regarding the electromagnetic wave attenuation, the prepared ferrites exhibit narrowband return losses (RL) by virtue of the cancellation of multiple reflections, when their thickness equals an odd multiple of quarter-wavelength. Interestingly, the zero-reflection conditions are satisfied in the vicinity of the ferromagnetic resonance. As the rare earth doping shifts this mechanism to lower frequencies, loss peaks with RL>46 dB occur at 4.1 GHz and 5 GHz for Y and La-doped Ni-Co-Zn spinels, whereas peaks with RL>40 dB appear at 18 GHz and 19 GHz for Y and La-doped Ni-Co spinels, respectively. The presented experimental findings underline the potential of cubic ferrites with high Co concentration in the suppression of electromagnetic reflections well above the 1 GHz region.

  3. Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method

    Science.gov (United States)

    Nikumbh, A. K.; Pawar, R. A.; Nighot, D. V.; Gugale, G. S.; Sangale, M. D.; Khanvilkar, M. B.; Nagawade, A. V.

    2014-04-01

    Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRExFe2-xO4 (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like MS, HC and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x≤0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe2O4 exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio MR/MS and magnetic moments may be due to dilution of the magnetic interaction.

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  5. A density functional theory study of electronic and magnetic properties of rare earth doped monolayered molybdenum disulphide

    Science.gov (United States)

    Majid, Abdul; Imtiaz, Anum; Yoshiya, Masato

    2016-10-01

    The effects of Rare Earth (RE) atoms Sm, Eu, Gd, Tb, and Dy doping on structural, electronic, and magnetic properties of single layer MoS2 were investigated using first principles calculations. The analysis of electronic properties pointed out the appearance of host-impurity hybrid states on the edges of principal bands of the material, which appeared to cause narrowing of its bandgap. The values of total magnetic moment were calculated as 3.3 μB, 8.1 μB, 8.5 μB, 6.8 μB, and 6.4 μB for Sm-, Eu-, Gd-, Tb-, and Dy-doped MoS2, respectively. The underestimation of magnetic moment in the case of Sm doping is found which is assigned to shielding of 4f moments and quenching of angular momentum caused by Sm 4f-S 3p hybridization. On the other hand, the observed overestimation of magnetic moments for Eu and Gd cases is likely to be due to increase in angular momentum due to indirect exchange interaction of highly localized 4f states via 5d or 6s conduction electrons. The findings of this work point out the possibilities of tuning the band gap and magnetic properties of monolayer MoS2 upon RE doping for realization of p-type ferromagnetic semiconductors.

  6. Phase stable rare earth garnets

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-06-11

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

  7. Temperature and magnetic field dependence of rare -earth ↔iron exchange resonance mode in a magnetic oxide studied with femtosecond magneto-optical Kerr effect

    Science.gov (United States)

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

    2016-08-01

    In magnetic materials, the exchange is the strongest quantum interaction due to the Pauli exclusion principle. For that reason it can induce high-frequency modes fexch of the magnetization precession. In this work we investigate these modes over a wide range of temperatures (50 -300 K ) and magnetic fields up to 10 T in a bismuth-doped garnet with perpendicular magnetic anisotropy by performing femtosecond magneto-optical pump-probe experiments. Near the compensation temperature TM the divergence of 1 /fexch(T ) allows identifying unambiguously fexch with the rare-earth ↔ iron exchange mode. In addition, at low temperature fexch is independent of the field as usually observed. In contrast, we find that near TM,fexch decreases linearly with an increasing magnetic field. This behavior is explained in the context of the ferromagnetic resonance theory by including the perturbation term linear in the external applied field Hext.

  8. Grain boundary engineering in sintered Nd-Fe-B permanent magnets for efficient utilization of heavy rare earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, Konrad

    2016-10-18

    The first part of the thesis investigates the diffusion of rare-earth (RE) elements in commercial sintered Nd-Fe-B based permanent magnets. A strong temperature dependence of the diffusion distance and resulting change in magnetic properties were found. A maximum increase in coercivity of ∼+350 kA/m using a Dy diffusion source occurred at the optimum annealing temperature of 900 C. After annealing for 6 h at this temperature, a Dy diffusion distance of about 4 mm has been observed with a scanning Hall probe. Consequently, the maximum thickness of grain boundary diffusion processed magnets with homogeneous properties is also only a few mm. The microstructural changes in the magnets after diffusion were investigated by electron microscopy coupled with electron probe microanalysis. It was found that the diffusion of Dy into sintered Nd-Fe-B permanent magnets occurs along the grain boundary phases, which is in accordance with previous studies. A partial melting of the Nd-Fe-B grains during the annealing process lead to the formation of so - called (Nd,Dy)-Fe-B shells at the outer part of the grains. These shells are μm thick at the immediate surface of the magnet and become thinner with increasing diffusion distance towards the center of the bulk. With scanning transmission electron microscopy coupled with electron probe analysis a Dy content of about 1 at.% was found in a shell located about 1.5 mm away from the surface of the magnet. The evaluation of diffusion speeds of Dy and other RE (Tb, Ce, Gd) in Nd-Fe-B magnets showed that Tb diffuses significantly faster than Dy, and Ce slightly slower than Dy, which is attributed to differences in the respective phase diagrams. The addition of Gd to the grain boundaries has an adverse effect on coercivity. Exemplary of the heavy rare earth element Tb, the nano - scale elemental distribution around the grain boundaries after the diffusion process was visualized with high resolution scanning transmission electron microscopy

  9. Characterization and recovery of rare earth elements from electronic scrap

    OpenAIRE

    Bristøl, Lene Marie Lysgaard

    2012-01-01

    The rare earth elements are a group of 17 elements consisting of the lantahnide series, scandium and yttrium. The application with the largest rare earth consumption is the permanent rare earth magnets. The neodymium-iron-boron magnets are the strongest permanent magnetic material known and are widely used. There is a concern that there will be a shortage in Nd-Fe-B magnets in short time. This has lead to an increased interest in the recycling of the rare earth magnets in the world.This proje...

  10. Chemically Inhomogeneous RE-Fe-B Permanent Magnets with High Figure of Merit: Solution to Global Rare Earth Criticality.

    Science.gov (United States)

    Jin, Jiaying; Ma, Tianyu; Zhang, Yujing; Bai, Guohua; Yan, Mi

    2016-08-24

    The global rare earth (RE) criticality, especially for those closely-relied Nd/Pr/Dy/Tb in the 2:14:1-typed permanent magnets (PMs), has triggered tremendous attempts to develop new alternatives. Prospective candidates La/Ce with high abundance, however, cannot provide an equivalent performance due to inferior magnetic properties of (La/Ce)2Fe14B to Nd2Fe14B. Here we report high figure-of-merit La/Ce-rich RE-Fe-B PMs, where La/Ce are inhomogeneously distributed among the 2:14:1 phase. The resultant exchange coupling within an individual grain and magnetostatic interactions across grains ensure much superior performance to the La/Ce homogeneously distributed magnet. Maximum energy product (BH)max of 42.2 MGOe is achieved even with 36 wt. % La-Ce incorporation. The cost performance, (BH)max/cost, has been raised by 27.1% compared to a 48.9 MGOe La/Ce-free commercial magnet. The construction of chemical heterogeneity offers recipes to develop commercial-grade PMs using the less risky La/Ce, and also provides a promising solution to the REs availability constraints.

  11. Chemically Inhomogeneous RE-Fe-B Permanent Magnets with High Figure of Merit: Solution to Global Rare Earth Criticality

    Science.gov (United States)

    Jin, Jiaying; Ma, Tianyu; Zhang, Yujing; Bai, Guohua; Yan, Mi

    2016-08-01

    The global rare earth (RE) criticality, especially for those closely-relied Nd/Pr/Dy/Tb in the 2:14:1-typed permanent magnets (PMs), has triggered tremendous attempts to develop new alternatives. Prospective candidates La/Ce with high abundance, however, cannot provide an equivalent performance due to inferior magnetic properties of (La/Ce)2Fe14B to Nd2Fe14B. Here we report high figure-of-merit La/Ce-rich RE-Fe-B PMs, where La/Ce are inhomogeneously distributed among the 2:14:1 phase. The resultant exchange coupling within an individual grain and magnetostatic interactions across grains ensure much superior performance to the La/Ce homogeneously distributed magnet. Maximum energy product (BH)max of 42.2 MGOe is achieved even with 36 wt. % La-Ce incorporation. The cost performance, (BH)max/cost, has been raised by 27.1% compared to a 48.9 MGOe La/Ce-free commercial magnet. The construction of chemical heterogeneity offers recipes to develop commercial-grade PMs using the less risky La/Ce, and also provides a promising solution to the REs availability constraints.

  12. In situ non-aqueous nucleation and growth of next generation rare-earth-free permanent magnets.

    Science.gov (United States)

    Yoon, Hyojung; Xu, Aoran; Sterbinsky, George E; Arena, Dario A; Wang, Ziying; Stephens, Peter W; Meng, Ying Shirley; Carroll, Kyler J

    2015-01-14

    Using a controllable wet chemical approach, the polyol process, we developed a cobalt carbide nanomagnet consisting of an assembly of Co2C and Co3C nanoparticles as an alternative to rare earth permanent magnets (PMs). The thermodynamically stable mixed phase cobalt carbide nanoparticles are shown to be acicular in morphology. Their exchange-coupled magnetic interaction possessing high maximum energy product of 20.7 kJ m(-3) and room temperature coercivity (2.9 kOe) has been confirmed through vibrating sample magnetometer (VSM) and first order reversal curves (FORCs). These metastable carbide nanoparticles offer improved magnetic properties compared to their pure bulk form. An understanding of the formation mechanism, using in situ time-resolved X-ray spectroscopy (TR-XAS), and the correlation between phase contributions to the properties are described in detail. Our strategy presents a controllable route to preparing the cobalt carbide nanomagnets, which could be potentially useful in permanent magnet clean energy applications. Additionally, the in situ apparatus offers a promising way to directly explore the effects of reaction variables for high-temperature wet chemical reactions.

  13. Large magnetic anisotropy predicted for rare-earth-free F e16 -xC oxN2 alloys

    Science.gov (United States)

    Zhao, Xin; Wang, Cai-Zhuang; Yao, Yongxin; Ho, Kai-Ming

    2016-12-01

    Structures and magnetic properties of F e16 -xC oxN2 are studied using adaptive genetic algorithm and first-principles calculations. We show that substituting Fe with Co in F e16N2 with a Co/Fe ratio ≤1 can greatly improve the magnetic anisotropy of the material. The magnetocrystalline anisotropy energy from first-principles calculations reaches 3.18 MJ / m3 (245.6 μeV per metal atom) for F e12C o4N2 , much larger than that of F e16N2 , and is one of the largest among the reported rare-earth-free magnets. From our systematic crystal structure searches, we show that there is a structure transition from tetragonal F e16N2 to cubic C o16N2 in F e16 -xC oxN2 as the Co concentration increases, which can be well explained by electron counting analysis. Different magnetic properties between the Fe-rich (x ≤8 ) and Co-rich (x >8 ) F e16 -xC oxN2 is closely related to the structural transition.

  14. Processing of rare earth concentrates

    Institute of Scientific and Technical Information of China (English)

    Pamela Alex; R. C. Hubli; A.K. Suri

    2005-01-01

    The paper describes process details for extraction of rare earths from an intermediate grade concentrate of Madhya Pradesh region in India and a South African slag. The xenotime concentrate obtained from the former place was an intermediate grade (47%) rare earth phosphate containing both monazite and xenotime. The South African slag was a low-grade waste product typically containing only 4% of rare earths. The rare earth resource concentrates have been treated individually by different methods such as alkali fusion and alkali leaching to convert them into their mixed oxides. Both types of materials have been processed and greater than 98% solubilization of metal values has been achieved in the intermediate grade xenotime and 80% from the South African slag. The residue of xenotime hydroxide has been washed thoroughly to collect the sodium phosphate, as by-product and the slurry pH have been adjusted to separate rare earths from thorium effectively. Other impurities such as uranium and iron have been removed by precipitation of rare earths by oxalic acid. It has been possible to recover >95% yttrium along with other rare earth oxides.

  15. Site-preference and valency for rare-earth sites in (R-Ce)(2)Fe14B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Alam, A; Khan, M; McCallum, RW; Johnson, DD

    2013-01-28

    Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)(2)Fe14B [R = La, Nd] using density functional theory (DFT) methods-including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data-almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 <= x <= 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x <= 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd, Ce) were predicted for a typical sample processing and verified experimentally. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4789527

  16. Site-preference and valency for rare-earth sites in (R-Ce)2Fe14B magnets

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Aftab [Ames Laboratory; Khan, Mahmud [Ames Laboratory; McCallum, R. W. [Ames Laboratory; Johnson, Duane D [Ames Laboratory

    2013-01-28

    Rare-earth (R) permanent magnets of R2Fe14B have technological importance due to their high energy products, and they have two R-sites (Wyckoff 4f and 4g, with four-fold multiplicity) that affect chemistry and valence. Designing magnetic behavior and stability via alloying is technologically relevant to reduce critical (expensive) R-content while retaining key properties; cerium, an abundant (cheap) R-element, offers this potential. We calculate magnetic properties and Ce site preference in (R1-xCex)2Fe14B [R=La,Nd] using density functional theory (DFT) methods—including a DFT+U scheme to treat localized 4f-electrons. Fe moments compare well with neutron data—almost unaffected by Hubbard U, and weakly affected by spin-orbit coupling. In La2Fe14B, Ce alloys for 0 ≤ x ≤ 1 and prefers smaller R(4f) sites, as observed, a trend we find unaffected by valence. Whereas, in Nd2Fe14B, Ce is predicted to have limited alloying (x ≤ 0.3) with a preference for larger R(4g) sites, resulting in weak partial ordering and segregation. The Curie temperatures versus x for (Nd,Ce) were predicted for a typical sample processing and verified experimentally.

  17. Multiple magnetic relaxation processes, magnetocaloric effect and fluorescence properties of rhombus-shaped tetranuclear rare earth complexes.

    Science.gov (United States)

    Gao, Hong-Ling; Jiang, Li; Liu, Shuang; Shen, Hai-Yun; Wang, Wen-Min; Cui, Jian-Zhong

    2016-01-07

    Seven new tetranuclear rare earth (RE) complexes [RE4(acac)4L6(μ3-OH)2] (HL = 5-(4-fluorobenzylidene)-8-hydroxylquinoline; acac = acetylacetonate; RE = Y (1), Eu (2), Gd (3), Tb (4), Dy (5), Tm (6) and Lu (7)) have been synthesized and completely characterized. Complex exhibits multiple zero-field slow magnetic relaxation processes typical of Single Molecule Magnets (SMMs). Two distinct slow magnetic relaxation processes, with effective energy barriers of Ueff = 48 K for the slow relaxation (SR) process and Ueff = 121 K for the fast relaxation (FR) process, are mainly attributed to the presence of two crystallographically independent Dy(III) sites. The magnetocaloric effect (MCE) was detected as -ΔSm(T) = 20.8 J kg(-1) K(-1) for complex . The fluorescence properties of complexes 1, 2, 4, 5 and 7 were also investigated. Complexes 2, 4 and 5 show the characteristic peaks for their corresponding RE(III) center, while complexes 1 and 7 show similar emission peaks to the Schiff base ligand when they are excited at the appropriate wavelength.

  18. On-the-fly machine-learning for high-throughput experiments: search for rare-earth-free permanent magnets.

    Science.gov (United States)

    Kusne, Aaron Gilad; Gao, Tieren; Mehta, Apurva; Ke, Liqin; Nguyen, Manh Cuong; Ho, Kai-Ming; Antropov, Vladimir; Wang, Cai-Zhuang; Kramer, Matthew J; Long, Christian; Takeuchi, Ichiro

    2014-09-15

    Advanced materials characterization techniques with ever-growing data acquisition speed and storage capabilities represent a challenge in modern materials science, and new procedures to quickly assess and analyze the data are needed. Machine learning approaches are effective in reducing the complexity of data and rapidly homing in on the underlying trend in multi-dimensional data. Here, we show that by employing an algorithm called the mean shift theory to a large amount of diffraction data in high-throughput experimentation, one can streamline the process of delineating the structural evolution across compositional variations mapped on combinatorial libraries with minimal computational cost. Data collected at a synchrotron beamline are analyzed on the fly, and by integrating experimental data with the inorganic crystal structure database (ICSD), we can substantially enhance the accuracy in classifying the structural phases across ternary phase spaces. We have used this approach to identify a novel magnetic phase with enhanced magnetic anisotropy which is a candidate for rare-earth free permanent magnet.

  19. On-the-fly machine-learning for high-throughput experiments: search for rare-earth-free permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kusne, Aaron Gilad [University of Maryland; Gao, Tieren [University of Maryland; Mehta, Apurva [SLAC National Accelerator Laboratory; Ke, Liqin [Ames Laboratory; Nguyen, Manh Cuong [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory; Antropov, Vladimir [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Kramer, Matthew J [Ames Laboratory; Long, Christian [University of Maryland; Takeuchi, Ichiro [University of Maryland

    2014-09-15

    Advanced materials characterization techniques with ever-growing data acquisition speed and storage capabilities represent a challenge in modern materials science, and new procedures to quickly assess and analyze the data are needed. Machine learning approaches are effective in reducing the complexity of data and rapidly homing in on the underlying trend in multi-dimensional data. Here, we show that by employing an algorithm called the mean shift theory to a large amount of diffraction data in high-throughput experimentation, one can streamline the process of delineating the structural evolution across compositional variations mapped on combinatorial libraries with minimal computational cost. Data collected at a synchrotron beamline are analyzed on the fly, and by integrating experimental data with the inorganic crystal structure database (ICSD), we can substantially enhance the accuracy in classifying the structural phases across ternary phase spaces. We have used this approach to identify a novel magnetic phase with enhanced magnetic anisotropy which is a candidate for rare-earth free permanent magnet.

  20. Preferred Orientation of Rare Earth (RE)-Doped Alumina Crystallites by an Applied Magnetic Field

    Science.gov (United States)

    2016-06-01

    imposed magnetic flux density, kB is Boltzmann’s constant, T is the absolute temperature, t is the time needed for a crystal to rotate a certain amount... axis . It is of interest to investigate what effect the identity of the dopant has on the response to the magnetic field. RE dopants praesodymium...9 Table 2 DFT calculated easy magnetic axis and maximal MAE (meV) indicating degree of

  1. China Rare Earth Holdings Limited

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    China Rare Earth Holdings Limited is a large trans-area corporation and a public company listed in Hong Kong Stock Exchange (Name: China Rare Earth, Code: 0769), with headquarter in Hong Kong. Located on the bank of beautiful Taihu Lake, the subsidiary in Yinxing covers area of 200,000 m2. It has nearly 1,000 employees, 30% of whom are technical staffs. After self-administration and effort, the company passed ISO 9001: 2000 and ISO 14000 Certificaitons.

  2. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Rare earth market remained depressed after the New Year affected by the weak demand. Purchaser preferred to consume inventories rather than increase the stockpile. There was a strong wait-and-see atmosphere in the market. Driven by the intense desire to sell out the commodities, traders further decreased their quoted price for rare earth products. Most persons in the market preferred to hold commodities and waited for a rise in the market after the Spring Festival.

  3. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    March 21-31,2012 Rare earth market rebounded holistically recently. Price of didymium products rose slightly after being stable for one month. There were also increases in the prices of europium oxide and terbium oxide, which led to a rush by phosphor plants. The market of yttrium-medium and europium-rich minerals remained stagnant though the rare earth market recovered. Price of the mineral was around RMB ¥210,000-250,000/ton.

  4. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    November 20-30.2011 Weak demand resulted in the slack rare market. Consumers did not intend to rep earth enish inventories yet and transactions of rare earth products were stagnant. The market of didymium-related products was in the doldrums. Demand for dysprosium-related products was sluggish. Inquiries for europium oxide (99.9%) were few and dealings of the product were difficult.

  5. Magnetization, Magnetocrystalline Anisotropy and the Crystalline Electric Field in Rare-Earth Al2 Compounds

    DEFF Research Database (Denmark)

    Purwins, H. -G.; Walker, E.; Barbara, B.;

    1974-01-01

    Magnetization measurements are reported for single crystals of PrAl2 in the range from 4.2K to 30K for magnetic fields up to 150 kOe applied in the (100), (110) and (111) directions. For these measurements, together with the magnetization results obtained earlier for TbAl2 the authors give...... a quantitative quantum mechanical description of the magnetization and the related magnetocrystalline anisotropy in terms of a cubic crystalline electric field and an isotropic exchange interaction. The parameters used in this description can be unified to good approximation to all REAl2 intermetallic compounds...

  6. Reduction in Current Consumption of Small DC Motor with Rare-Earth Flexible Bonded Magnets Prepared by Powder Compacting Press and Hot Rolling

    Science.gov (United States)

    Yamashita, Fumitoshi; Watanabe, Akihiko; Fukunaga, Hirotoshi

    The usage of high-performance rare-earth magnets is one of the key technologies in the development of efficient small motors. Ring-shaped melt-spun Nd-Fe-B bonded magnets, prepared using a powder compacting press and/or injection molding, are generally used in typical applications to small efficient motors. For exploiting the maximum characteristics according to the variety of magnetic powder, however, the preparation method of the magnet, the magnet form, and the motor design needs to be changed for high-productivity as well as for improving total performance, including the magnetic properties of bonded magnets. This paper reports recent achievements in new preparation processes for rare-earth bonded magnets and small motors using new materials other than Nd-Fe-B melt-spun powder. This paper especially focuses on the method for maximally exploiting certain rare-earth magnetic powders . Furthermore, reduction in the current consumption of the small DC motor using the developed technique is reported.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Shuang [Ames Lab. and Iowa State Univ., Ames, IA (United States)

    2008-01-01

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

  8. Magnetic Behaviour of Tb/Si Nanoscale Multilayers with Small Thickness of Rare Earth Layers

    Institute of Scientific and Technical Information of China (English)

    A.V.Svalov; V.O.Vas'kovskiy; G.V.Kurlyandskaya; J.M.Barandiaran; N.N.Schegoleva; A.N.Sorokin

    2007-01-01

    We report the magnetic properties of Tb/Si multilayers obtained by rf-sputtering at the Tb layer thickness LTb = 3 nm. Analysis of the magnetization processes indicates more complex behaviour than canonical spin-glass transition. It is more probable that these multilayers contain both Tb superparamagnetic particles and Tb-Si spin-glass alloys.

  9. Magnetic structures and related properties of some rare-earth intermetallic compounds, RCu 2

    Science.gov (United States)

    Lebech, B.; Smetana, Z.; S̆íma, V.

    1987-12-01

    The magnetic structures and some relevant bulk magnetic properties of R(Cu, Ni) 2 (R = Tb, Tb zY 1- z, Dy, Ho, Er and Tm) are summarized. Basically, the magnetic structures are antiferromagnetically modulated with propagation vector {1}/{3}a∗. For R = Tb, Dy, Ho the a-axis anisotropy dominates and the structures are longitudinally modulated. For R = Tm, Er (probably) the b-axis anisotropy dominates and this results in transversely modulated structures. For R = Tb, Dy the structures are collinear, For R = Ho, Er, Tm (probably) an incommensurate modulation coexists with the commensurate a∗-axis modulation at the lowest temperature.

  10. Magnetic properties of R2Mn207 pyrochlore rare-earth solid solutions

    OpenAIRE

    Imamura, N.; Karppinen, Maarit; Yamauchi, H.; Goodenough, J. B.

    2010-01-01

    Three (R,R′)2Mn2O7 ferromagnetic pyrochlore systems were studied to investigate the role of the R3+ ionic size versus 4f moment on the magnetic properties of the Mn2O7 sublattice. The Curie temperature TC=18±1 K for R=Y and Lu remained nearly constant for (Y1−xLux)2Mn2O7 but the magnetization data show characteristics of spin-glass behavior in low magnetic fields, and at 5 T, the magnetization fails to reach the expected 3 μB/Mn4+ found by 0.5 T in Tl2Mn2O7 and In2Mn2O7. A frustrated, minor a...

  11. Current driven domain wall motion in rare-earth transition metal alloys with perpendicular magnetic anisotropy.

    Science.gov (United States)

    Li, Songtian; Liu, Xiaoxi; Morisako, Akimistu

    2012-09-01

    The domain wall movement behaviors under current combining with magnetic field in perpendicularly magnetized TbFeCo wire were studied by a polar magneto-optical Kerr effect microscope. The velocity for domain wall creeping along electrons flowing direction was found to be apparently higher than that of domain wall creeping against electrons flowing, which is the signature of the spin transfer torque effect. By employing the modified field-driven creep motion law, a spin transfer efficiency of 2.7 Oe cm2/10(6) A was determined for TbFeCo wire by treating the spin transfer torque as an effective field adding to the external field. The high spin transfer efficiency suggests that perpendicularly magnetized system with sharp domain walls in TbFeCo film shows high superiorities for applications in spin transfer torque based devices compared with in-plane magnetized systems.

  12. The interplay of long-range magnetic order and single-ion anisotropy in rare earth nickel germanides

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Z.

    1999-05-10

    This dissertation is concerned with the interplay of long-range order and anisotropy in the tetragonal RNi{sub 2}Ge{sub 2} (R = rare earth) family of compounds. Microscopic magnetic structures were studied using both neutron and x-ray resonant exchange scattering (XRES) techniques. The magnetic structures of Tb, Dy, Eu and Gd members have been determined using high-quality single-crystal samples. This work has correlated a strong Fermi surface nesting to the magnetic ordering in the RNi{sub 2}Ge{sub 2} compounds. Generalized susceptibility, {chi}{sub 0}(q), calculations found nesting to be responsible for both incommensurate ordering wave vector in GdNi{sub 2}Ge{sub 2}, and the commensurate structure in EuNi{sub 2}Ge{sub 2}. A continuous transition from incommensurate to commensurate magnetic structures via band filling is predicted. The surprisingly higher T{sub N} in EuNi{sub 2}Ge{sub 2} than that in GdNi{sub 2}Ge{sub 2} is also explained. Next, all the metamagnetic phases in TbNi{sub 2}Ge{sub 2} with an applied field along the c axis have been characterized with neutron diffraction measurements. A mixed phase model for the first metamagnetic structure consisting of fully-saturated as well as reduced-moment Tb ions is presented. The moment reduction may be due to moment instability which is possible if the exchange is comparable to the low-lying CEF level splitting and the ground state is a singlet. In such a case, certain Tb sites may experience a local field below the critical value needed to reach saturation.

  13. Exploring new phases of Fe3-x Co x C for rare-earth-free magnets

    Science.gov (United States)

    Wu, S. Q.; Balamurugan, B.; Zhao, X.; Yu, S.; Nguyen, Manh Cuong; Sun, Y.; Valloppilly, S. R.; Sellmyer, D. J.; Ho, K. M.; Wang, C. Z.

    2017-06-01

    Structures, magnetic moments, and magnetocrystalline anisotropy energies of the Fe3-x Co x C intermetallic compounds are systematically investigated using adaptive genetic algorithm (AGA) crystal-structure predictions and first-principles calculations. Besides reproducing the known cementite (Pnma) structure of Fe3C, i.e. x  =  0, the AGA searches also capture several new metastable phases within the room-temperature range. In particular, a bainite (P6322) structure exhibits the largest magnetic moment among all low-energy structures, and its energy is only 4 meV/atom higher than the cementite (Pnma) phase. The atomic structure of the Pnma Fe2CoC phase, i.e. x  =  1, is also identified, and the calculated x-ray diffraction spectrum, magnetocrystalline anisotropy energy, and saturation magnetization based on the structure from our theoretical study are in good agreement with experiment.

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

    Science.gov (United States)

    1989-01-01

    aublattice anisotropy. 1. Introduction The compound Nd2Fe14B is the basic material for the production of high quality Permanent magniets [1, 21. It...the in-plane anisotropy is in disagreement with the observed different magnetiza- tion curves for Nd2Fe14B in the [1001 and [1101 directions [101... Nd2Fe14B based permanent magnets so far. The grain size of the magnets also strongly der ds on the processing technique. The electron micrographs of Fig

  15. High-field magnetization of rare-earth ions in scandium

    DEFF Research Database (Denmark)

    Roeland, L. W.; Touborg, P.

    1978-01-01

    The magnetic moments of Tb, Dy, or Er ions in dilute Sc single-crystal alloys have been measured in fields up to 280 × 105 A/m (350 kOe). The Zeeman energies in this high field are comparable to the total crystal-field splittings. This gives rise to characteristic features in the magnetization...... curves. The crystal-field parameters obtained previously from experiments in low fields and the Zeeman interaction give a satisfactory quantitative acount of the experimental results....

  16. Effect of rare earth dopants on the magnetic ordering of frustrated h-YMnO3

    Science.gov (United States)

    Sharma, Neetika; Das, A.; Prajapat, C. L.; Singh, M. R.

    2016-12-01

    In this report the combined effects of chemical pressure and R-Mn interaction on the structural and magnetic properties of frustrated h-YMnO3 have been investigated. Towards this, neutron powder diffraction and magnetization measurements were carried out on isostructural compounds Y1-xRxMnO3(R=Yb, Er, Tb, Ho; x≤0.2) with hexagonal structure (P63cm space group). The dopants are evenly distributed between the two Yttrium sites. The unit cell volume shows a linear increase with average A-site ionic radii, . The average apical a and planar p bond lengths are found to increase with . The tilting angle of the MnO5 polyhedron decreases linearly with increase in , whereas the buckling angle remains constant. No significant change in TN (within 10 K) is observed on doping. The temperature variation of the volume indicates an anomalous reduction in volume at TN which is found to be correlated with the square of the antiferromagnetic Mn moment. A spin reorientation behavior (evident from a change in the irreducible representation (IR) Γ3 to Γ4) is observed on decreasing from 1.019 Å (Y) to 1.012 Å (Yb) similar to that reported in external pressure studies on YMnO3. Additional interaction between the doped R and Mn influences the magnetic structure in the case of Ho and Tb doped samples. With Ho doping at Y site, the magnetic structure is described by IR Γ3 alone for 5 K≤T<35 K and a mixture of Γ3 and Γ4 for T≥35 K. However, in Tb doped sample, the magnetic structure is better described by Γ4Tb,Mn IR with additional moment on Tb. The frustration parameter, f reduces from 6 to 1 in the doped samples. A combination of chemical pressure effect and magnetic coupling between the magnetic R ion and Mn moments thus describes the magnetic structures and relieves the frustration effects inherent to the quasi-two dimensional Mn moment ordering.

  17. Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Nikumbh, A.K., E-mail: aknik@chem.unipune.ac.in; Pawar, R.A.; Nighot, D.V.; Gugale, G.S.; Sangale, M.D.; Khanvilkar, M.B.; Nagawade, A.V.

    2014-04-15

    Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRE{sub x}Fe{sub 2−x}O{sub 4} (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like M{sub S}, H{sub C} and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x≤0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe{sub 2}O{sub 4} exhibit the particle size 36.1 to 67.8 nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio M{sub R}/M{sub S} and magnetic moments may be due to dilution of the magnetic interaction.

  18. On the Origin of the Large Magnetic Anisotropy of Rare Earth-Cobalt Compounds

    DEFF Research Database (Denmark)

    Szpunar, B.; Lindgård, Per-Anker

    1979-01-01

    Experimental data on the magnetocrystalline anisotropy in Co, YCo5, GdCo5, SmCo5 and Y2Co17 is analysed using a single-ion crystal field and isotropic exchange interaction. The large magnetic anisotropy at high temperatures in the alloys is due to significant deviations in the alloy lattices...

  19. Switching the in-plane easy axis by ion implantation in rare earth based magnetic films.

    Science.gov (United States)

    Buckingham, A R; Wang, D; Stenning, G B G; Bowden, G J; Nandhakumar, I; Ward, R C C; de Groot, P A J

    2013-02-27

    Ar(+) ions have been implanted into Laves phase epitaxial thin films of YFe(2) and DyFe(2). Magneto-optical Kerr effect and vibrating sample magnetometry experiments show that the easy and hard axes of magnetization in both materials rotate through an in-plane angle of 90°, whilst the strength of the magnetic anisotropy remains unaltered. This is supported by OOMMF computational modelling. Atomic force microscopy confirms that the film roughness is not affected by implanted ions. X-ray diffraction data show that the lattice parameter expands upon ion implantation, corresponding to a release of strain throughout the entire film following implantation with a critical fluence of 10(17) Ar(+) ions cm(-2). The anisotropy of the films is linked to the strain and from these data it is concluded that the source of anisotropy alters from one where magnetoelastic and magnetocrystalline effects compete to one which is governed solely by magnetocrystalline effects. The ability to locally tune the source of magnetic anisotropy without affecting the film surface and without inducing or eliminating anisotropy could be important in the fabrication of high density magnetic data storage media, spintronic devices and magneto-optical materials.

  20. Study of structure and magnetic properties of rare earth doped BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, Pittala; Srinath, S., E-mail: srinath@uohyd.ac.in

    2014-09-01

    RE{sub x}Bi{sub 1−x}FeO{sub 3} (RE=La, Gd and Ho) samples were synthesized by a solid state reaction method and investigated for structure and magnetic properties. XRD shows that La and Ho dopings at A-site effectively reduce the secondary phase formation. A structural phase transition is observed to orthorhombic phase with all RE elements above certain concentration limit. La doping results in the observation of huge coercivity of 10 kOe and Ho doping results in high magnetic moment among all the RE elements. Gd and Ho doped samples show a pinching in the M–H loops with minimum H{sub C}.

  1. Hf-Co and Zr-Co alloys for rare-earth-free permanent magnets.

    Science.gov (United States)

    Balamurugan, B; Das, B; Zhang, W Y; Skomski, R; Sellmyer, D J

    2014-02-12

    The structural and magnetic properties of nanostructured Co-rich transition-metal alloys, Co(100-x)TMx (TM = Hf, Zr and 10 ≤ x ≤ 18), were investigated. The alloys were prepared under non-equilibrium conditions using cluster-deposition and/or melt-spinning methods. The high-anisotropy HfCo7 and Zr2Co11 structures were formed for a rather broad composition region as compared to the equilibrium bulk phase diagrams, and exhibit high Curie temperatures of above 750 K. The composition, crystal structure, particle size, and easy-axis distribution were precisely controlled to achieve a substantial coercivity and magnetization in the nanostructured alloys. This translates into high energy products in the range of about 4.3-12.6 MGOe, which are comparable to those of alnico.

  2. (BRI) Direct and Inverse Design Optimization of Magnetic Alloys with Minimized Use of Rare Earth Elements

    Science.gov (United States)

    2016-02-02

    of the desired magnetic properties of the alloys. Sensitivity analysis of the variation of concentrations of each of the alloying elements revealed ...capable of exploring yet unexplored domains of the design space. Sensitivity analysis also revealed that certain alloying elements have negligible...Principal Investigator during the previous decade and applied to design optimization of H-type steels , Ni DISTRIBUTION A: Distribution approved for

  3. Large magnetic-field-induced strains in rare earth polycrystalline Ni-Mn-Ga

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zengqi; WU Shuangxia; WANG Fangshu; WANG Qiang; JIANG Liping; WANG Xinlin

    2004-01-01

    The magnetic-field-induced strains (MFIS) of polycrystalline Ni50Mn29Ga21 alloys containing Tb were studied. A large MFIS of - 1.10% was obtained under compressive prestress conditions. The addition of Tb can fine the crystal grains, enhance the bending strength obviously, and make MFIS increase further, indicating that a moderate amount of Tb does not hinder twin boundary motion and it conversely makes the material more practical.

  4. Fluorescent magnetic Fe3 O4 /rare Earth colloidal nanoparticles for dual-modality imaging.

    Science.gov (United States)

    Zhu, Haie; Shang, Yalei; Wang, Wenhao; Zhou, Yingjie; Li, Penghui; Yan, Kai; Wu, Shuilin; Yeung, Kelvin W K; Xu, Zushun; Xu, Haibo; Chu, Paul K

    2013-09-09

    Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two-step, seed emulsifier-free emulsion polymerization in the presence of oleic acid and sodium undecylenate-modified Fe3 O4 nanoparticles (NPs). The Fe3 O4 /poly(St-co-GMA) nanoparticles are first synthesized as the seed and Eu(AA)3 Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core-shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T2 relaxivity of the FMCNPs is 353.86 mM(-1) S(-1) suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T2 -weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.

  5. Rare Earth Separation in China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    During the last decade, China rare earth (RE) industry has made significant progress and become one of the most important producers in the world. In this paper, the recent developments in both fundamental research and industrial application are briefly reviewed: (1) the development and application of Theory of Countercurrent Extraction, (2) the novel solvent extraction process and its application in industry for separating heavy rare earth elements (Tm, Yb, Lu), yttrium (Y), and scandium (Sc), (3) the on-line analysis and automatic control of countercurrent extraction, (4) the eco-friendly process for RE/Th separation of bastnasite in Sichuan Province and electrochemical process for Eu/RE separation, and (5) the optimized flowcharts for typical rare earth minerals in China.

  6. Synthesis, characterization, and cytotoxicity in human erythrocytes of multifunctional, magnetic, and luminescent nanocrystalline rare earth fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Grzyb, Tomasz, E-mail: tgrzyb@amu.edu.pl [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland); Mrówczyńska, Lucyna [Adam Mickiewicz University, Department of Cell Biology, Faculty of Biology (Poland); Szczeszak, Agata [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland); Śniadecki, Zbigniew [Polish Academy of Sciences, Institute of Molecular Physics (Poland); Runowski, Marcin [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland); Idzikowski, Bogdan [Polish Academy of Sciences, Institute of Molecular Physics (Poland); Lis, Stefan [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland)

    2015-10-15

    Multifunctional nanoparticles exhibiting red or green luminescence properties and magnetism were synthesized and thoroughly analyzed. The hydrothermal method was used for the synthesis of Eu{sup 3+}- or Tb{sup 3+}-doped GdF{sub 3}-, NaGdF{sub 4}-, and BaGdF{sub 5}-based nanocrystalline materials. The X-ray diffraction patterns of the samples confirmed the desired compositions of the materials. Transmission electron microscope images revealed the different morphologies of the products, including the nanocrystal sizes, which varied from 12 nm in the case of BaGdF{sub 5}-based nanoparticles to larger structures with dimensions exceeding 300 nm. All of the samples presented luminescence under ultraviolet irradiation, as well as when the samples were in the form of water colloids. The highest luminescence was observed for BaGdF{sub 5}-based materials. The obtained nanoparticles exhibited paramagnetism along with probable evidence of superparamagnetic behavior at low temperatures. The particles’ magnetic characteristics were also preserved for samples in the form of a suspension in distilled water. The cytotoxicity studies against the human erythrocytes indicated that the synthesized nanoparticles are non-toxic because they did not cause the red blood cells shape changes nor did they alter their membrane structure and permeabilization.

  7. Temperature dependent coercivity and magnetization of light rare-earth Nd doped permalloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chen [Physics Department, Southeast University, Nanjing 211189 (China); Fu, Yu [Physics Department, Southeast University, Nanjing 211189 (China); Institut Nanosciences et Cryogénie, CEA, 38054 Grenoble (France); Zhang, Dong [Physics Department, Southeast University, Nanjing 211189 (China); School of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China); Yuan, Shijun [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); Dong, Shuai [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Hongru [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-01-15

    The temperature dependence of the magnetic properties of Ni{sub 80}Fe{sub 20} thin films with dilute Nd dopants has been studied. The effect of Nd dopants on the hysteresis loops of Nd-doped Ni{sub 80}Fe{sub 20} thin films is small at room temperature but large at low temperature. The measurements show an interesting temperature dependence of the coercivity with different concentrations of Nd impurities, which might be related to the film structure. The temperature dependence of the saturation magnetization for Nd-doped Ni{sub 80}Fe{sub 20} thin films is fitted by a theoretical expression of spin-wave excitation plus Stoner-type-like contribution, in which the spin-wave excitation plays a main role at low temperature. The spin-wave stiffness constant D evaluated from the fitting shows a strong doping concentration dependence. - Highlights: • The abnormal coercivity behavior of Nd-doped Permalloy thin films is studied. • The mechanism of temperature dependence of coercivity is discussed. • The effect of Nd dopants on temperature dependence of Ms is studied. • Spin-wave excitations and Stoner-type excitations are discussed quantitatively.

  8. Synthesis, characterization, and cytotoxicity in human erythrocytes of multifunctional, magnetic, and luminescent nanocrystalline rare earth fluorides

    Science.gov (United States)

    Grzyb, Tomasz; Mrówczyńska, Lucyna; Szczeszak, Agata; Śniadecki, Zbigniew; Runowski, Marcin; Idzikowski, Bogdan; Lis, Stefan

    2015-10-01

    Multifunctional nanoparticles exhibiting red or green luminescence properties and magnetism were synthesized and thoroughly analyzed. The hydrothermal method was used for the synthesis of Eu3+- or Tb3+-doped GdF3-, NaGdF4-, and BaGdF5-based nanocrystalline materials. The X-ray diffraction patterns of the samples confirmed the desired compositions of the materials. Transmission electron microscope images revealed the different morphologies of the products, including the nanocrystal sizes, which varied from 12 nm in the case of BaGdF5-based nanoparticles to larger structures with dimensions exceeding 300 nm. All of the samples presented luminescence under ultraviolet irradiation, as well as when the samples were in the form of water colloids. The highest luminescence was observed for BaGdF5-based materials. The obtained nanoparticles exhibited paramagnetism along with probable evidence of superparamagnetic behavior at low temperatures. The particles' magnetic characteristics were also preserved for samples in the form of a suspension in distilled water. The cytotoxicity studies against the human erythrocytes indicated that the synthesized nanoparticles are non-toxic because they did not cause the red blood cells shape changes nor did they alter their membrane structure and permeabilization.

  9. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    August 20-31, 2011 Rare earth market did not show the sign of picking-up and remained stagnant recently. Most suppliers continued to decrease their quoted price, but leading producers in northern and southern China did not adjust their quoted price. Most rare earth plants in southern China had not yet resumed production. Quoted price of didymium products swung and the quoted prices of dysprosium-related products were slipping affected by weak demand. Inquiries for europium oxide were decreasing affected by the slow phosphor market.

  10. 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.

  11. Influence of Rare Earth (Gd3+) on Structural, Gigahertz Dielectric and Magnetic Studies of Cobalt ferrite

    Science.gov (United States)

    Pervaiz, Erum; Gul, I. H.

    2013-06-01

    A series of Gd3+ doped nanocrystalline Co-ferrites CoGdxFe2-xO4 (x = 0.0 to 0.1) has been prepared by sol-gel auto combustion technique. Structural and morphology studies were performed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Indexed XRD patterns confirm the formation of pure cubic spinel phase. Average crystallite sizes ranges from 16 nm to 25 nm ±2, were calculated from Sherrer's formula and Williamson Hall plots. Crystal strain increases with increase in doping amount of trivalent Gd ion. Lattice constant (a) and crystallite size D (311) increases with increase in Gd3+ concentration due to large ionic radii (0.94nm) of Gd3+ replacing Fe3+ (0.64nm). SEM images show the spherical morphology and uniform size distribution. Room temperature DC electrical resistivity decreases (~106) for x=0.025 then increases up to x=0.1 ~ (4.5×107). Dielectric properties have been studied using RF Impedance/material analyzer in the frequency range of 1 MHz to 1GHz. All the studied samples show a semi-conducting behavior as Permittivity and tangent loss (tanδ) decreases with the substitution of Gd3+ in parent crystal structure and have values of 4.92 and 0.016 at 1 GHz respectively. Complex impedance and Complex electric modulus plots were further studied for complete contribution of grains and grain boundary resistances to conduction and resonance frequencies respectively. Magnetic studies by Vibrating Sample Magnetometer (VSM) shows that magnetization (Ms) decreases with increase in Gd3+ concentration from 63 emu/gm to 27.26 emu/gm. Coercivity (Hc) first decreases for x=0.025, after which it increases to 2308 Oe for x=0.1.

  12. Magnetocaloric effect of RM2 (R = rare earth, M = Ni, Al) intermetallic compounds made by centrifugal atomization process for magnetic refrigerator

    Science.gov (United States)

    Matsumoto, K.; Asamato, K.; Nishimura, Y.; Zhu, Y.; Abe, S.; Numazawa, T.

    2012-12-01

    RM2 (R = rare earth, M = Al, Ni and Co) compounds have large entropy change and magnetic transition temperatures can be controlled by change of R and/or M so that are suitable to a magnetic refrigerator for hydrogen liquefaction under development. In order to improve refrigerator performance, spherical powdered HoAl2, DyAl2, and GdNi2 compounds with submillimeter diameter were synthesized by centrifugal atomization process. By measuring the magnetization and heat capacity, we obtained entropy change by magnetic fields and entropy as functions of temperature and magnetic field, which are essential for analysing the magnetic refrigeration cycle. All samples showed sharp magnetic transitions and had good potentials for use in magnetic refrigeration.

  13. 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.

  14. Development Trend of Rare Earth Standardion Work

    Institute of Scientific and Technical Information of China (English)

    Ma Jie; Lin Jirong; Zhao Fei; Zhang Xiuyan

    2004-01-01

    Rare earth standardization was developed along with rare earth industry.In recent decades, great advances have been made in China rare earth industry.This paper describes the status of rare earth standardization, problems existed and ways to perfect.Now the number of Chinese Rare Earth Standards has increased to 232 with expanding of the categories and covering scope of rare earth products.But the present standard system cannot be completely suited with rare earth production and trade, and not keep pace with the advance of technology.Standards are important rules in world trade and must be acted on.

  15. Probing electronic density of states and magnetic interactions at the rare-earth site in ErBa/sub 2/Cu/sub 3/O/sub 7/

    Energy Technology Data Exchange (ETDEWEB)

    Walter, U.; Fahy, S.; Zettl, A.; Louie, S.G.; Cohen, M.L.; Tejedor, P.; Stacy, A.M.

    1987-12-01

    By exploiting the 4f-shell properties of Er in the high-T/sub c/ superconductor ErBa/sub 2/Cu/sub 3/O/sub 7/, we find by inelastic magnetic neutron scattering that the electrostatic field around the rare-earth site is anomalously large. Above T/sub c/ there exists considerable magnetic interaction between the conduction electrons and the rare-earth's 4f shell: N(E/sub F/)J/sub ex/ = 0.025. This interaction is lost in the superconducting state. The ground-state magnetic moment of Er in the host lattice is ..mu../sub e//sub f//sub f/ = 5.3..mu../sub B/. .AE

  16. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    June 20-30, 2011 Prices of heavy rare earth products remained soaring. The same happened to dysprosium and its related products due to tight supply. Separation plants held tightly of europium oxide. Refining plants took a positive attitude toward the ma

  17. Rare earths & climate change,new energy,energy conservation and pollution reduction(continued)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Ⅲ.Contribution of rare earths to energy conservation Rechargeable batteries and rare earth permanent magnetic motor matching with batteries in every Prius car consume approximately 10 kg of rare-earth hydro-gen storage materials and 2 kg of rare earth permanent magnetic materials respectively.

  18. Experimental research on the residual magnetization of a rare-earth permanent magnet for a cryogenic undulator

    Institute of Scientific and Technical Information of China (English)

    He Yong-Zhou

    2013-01-01

    The magnetic properties of commercial polycrystalline Nd2Fe14B (N50M,N45H,N40SH,N35EH) and Sm2Co17 (XG30/20,XG26/25,XG22/20) magnets at cryogenic temperatures were tested by using a comprehensive physical properties measurement system (PPMS).The results show that the spin tilt temperature Tst of Nd2Fe14B magnets is closely related to intrinsic coercivity Hci,N50M and N45H with smaller Hci show a residual magnetization jump at 235 K and 225 K,respectively.For Sm2Co17 magnets,in 50-300 K,with temperature decreasing,residual magnetization Mrc shows a nearly linear increase,while in 10-50 K,Mrc has little change.The research results provide a reference for cryogenic undulators and other high-precision cryogenic devices.

  19. Quantum jumps in magneto-optical effects and magnetization of rare-earth compounds in ultrahigh magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tatsenko, O.M.; Platonov, V.V.; Kykov, A.I.; Dolotenko, M.I. [Russian Federal Nuclear Center-VNIIEF (Russian Federation); Zvezdin, A.K. [Institute of General Physics, Moscow (Russian Federation); Solem, J.C.; Fowler, C.M.; Goettee, J.D.; Rickel, D.; Campbell, L.J.; Veeser, L.; Sheppard, M.; Lacerda, A.H.; King, J.C.; Rodriquez, P.J.; Bartram, D.E.; Clark, R.G. [Los Alamos National Laboratory (United States); Kane, B.E.; Dzurak, A.S.; Facer, G.R. [University of New South Wales (Australia); Miura, N.; Takamasu, T.; Nakagawa, H. [University of Tokyo (Japan). ISSP; Yokoi, H. [NIMCR, Tsukuba (Japan); Brooks, J.S.; Engel, L.W. [Florida State University (United States).NHMFL; Pfeiffer, L.; West, K.W. [Lucent Technologies (United States); Maverick, A.W.; Butler, L.G. [Louisiana State University (United States); Lewis, W.; Gallegos, C.H. [Bechtel Nevada (United States); Marshall, B. [Bechtel Special Technologies Laboratory (United States)

    1998-07-01

    The experimental results of Faraday rotation (FR) measurements in the sample with Eu{sup 3+} ion at 4 K in high magnetic fields up to 700 T ('Dirac Series' - Los Alamos) are presented. The magnetic field is produced by the explosive-driven flux-compression generator MC-1. Measurements have been carried using 850 nm light at liquid helium temperature. The magnetic field-induced quantum reorientation of the spin and orbital magnetic moments in the Sm{sup 3+} and Eu{sup 3+} ions have been investigated.

  20. Fast preconcentration of trace rare earth elements from environmental samples by di(2-ethylhexyl)phosphoric acid grafted magnetic nanoparticles followed by inductively coupled plasma mass spectrometry detection

    Science.gov (United States)

    Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

    2017-10-01

    In this work, di(2-ethylhexyl)phosphoric acid (P204) grafted magnetic nanoparticles were synthesized by fabricating P204 onto Fe3O4@TiO2 nanoparticles based on Lewis acid-base interaction between Ti and phosphate group under weakly acidic condition. The prepared Fe3O4@TiO2@P204 nanoparticles exhibited excellent selectivity for rare earth elements, and good anti-interference ability. Based on it, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for fast preconcentration and determination of trace rare earth elements in environmental samples. Under the optimal conditions, the detection limits of rare earth elements were in the range of 0.01 (Tm)-0.12 (Nd) ng L- 1 with an enrichment factor of 100-fold, and the relative standard deviations ranged from 4.9 (Pr) to 10.7% (Er). The proposed method was successfully applied to the determination of rare earth elements in environmental samples, including river water, lake water, seawater and sediment.

  1. Rare earth permanent-magnet alloys’ high temperature phase transformation in situ and dynamic observation and its application in material design

    CERN Document Server

    Pan, Shuming

    2013-01-01

    The process of high temperature phase transition of rare earth permanent-magnet alloys is revealed by photographs taken by high voltage TEM. The relationship between the formation of nanocrystal and magnetic properties is discussed in detail, which effects alloys composition and preparation process. The experiment results verified some presumptions, and were valuable for subsequent scientific research and creating new permanent-magnet alloys. The publication is intended for researchers, engineers and managers in the field of material science, metallurgy, and physics. Prof. Shuming Pan is senior engineer of Beijing General Research Institute of Non-ferrous Metal.

  2. Rare-Earth-Free Permanent Magnets for Electrical Vehicle Motors and Wind Turbine Generators: Hexagonal Symmetry Based Materials Systems Mn-Bi and M-type Hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yang-Ki [University of Alabama; Haskew, Timothy [University of Alabama; Myryasov, Oleg [University of Alabama; Jin, Sungho [University of California San Diego; Berkowitz, Ami [University of California San Diego

    2014-06-05

    The research we conducted focuses on the rare-earth (RE)-free permanent magnet by modeling, simulating, and synthesizing exchange coupled two-phase (hard/soft) RE-free core-shell nano-structured magnet. The RE-free magnets are made of magnetically hard core materials (high anisotropy materials including Mn-Bi-X and M-type hexaferrite) coated by soft shell materials (high magnetization materials including Fe-Co or Co). Therefore, our research helps understand the exchange coupling conditions of the core/shell magnets, interface exchange behavior between core and shell materials, formation mechanism of core/shell structures, stability conditions of core and shell materials, etc.

  3. Analysis and Outlook of Global Rare Earth Market

    Institute of Scientific and Technical Information of China (English)

    XIONG Jiaqi

    2008-01-01

    @@ When enterd into 21st century,global rare earth market exhibits pleasing situation in recent years,profitig from fast development of global economy.China represented nearly 60% of global rare earth consumption in 2007.Rare earth consumtion in five advanced materisls including permanent magnets,polishing powder,hydrogen storage materisls,fluorescent materials and auto catalysts accounted for 60% of the tutal consumption.

  4. Magnetic, resonance, and optical properties of Cu3Sm (SeO3)2O2Cl : A rare-earth francisite compound

    Science.gov (United States)

    Zakharov, K. V.; Zvereva, E. A.; Markina, M. M.; Stratan, M. I.; Kuznetsova, E. S.; Dunaev, S. F.; Berdonosov, P. S.; Dolgikh, V. A.; Olenev, A. V.; Klimin, S. A.; Mazaev, L. S.; Kashchenko, M. A.; Ahmed, Md. A.; Banerjee, A.; Bandyopadhyay, S.; Iqbal, A.; Rahaman, B.; Saha-Dasgupta, T.; Vasiliev, A. N.

    2016-08-01

    In this combined experimental and theoretical paper, we study the properties of Cu3Sm (SeO3)2O2Cl belonging to the francisite family of compounds, which are novel frustrated layered compounds. Cu3Sm (SeO3)2O2Cl is synthesized through a solid state reaction. Characterizations through measurements of magnetization, specific heat, X-band electron spin resonance, and rare-earth optical spectroscopy, establish that the compound orders antiferromagnetically at TN=35 K and undergoes a spin-reorientation phase transition at TC=8.5 K due to the interplay of anisotropies in transition metal and rare-earth subsystems. The ground state Kramers doublet of Sm is found to split only at T kagome-type magnetic subsystem of Cu3Sm (SeO3)2O2Cl .

  5. 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.

  6. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3

    Science.gov (United States)

    Sharma, Mohit K.; Basu, Tathamay; Mukherjee, K.; Sampathkumaran, E. V.

    2016-10-01

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides.

  7. The Earth's Magnetic Field

    OpenAIRE

    Edda Lína Gunnarsdóttir 1988

    2012-01-01

    The Earth's magnetic field is essential for life on Earth, as we know it, to exist. It forms a magnetic shield around the planet, protecting it from high energy particles and radiation from the Sun, which can cause damage to life, power systems, orbiting satellites, astronauts and spacecrafts. This report contains a general overview of the Earth's magnetic field. The different sources that contribute to the total magnetic field are presented and the diverse variations in the field are describ...

  8. Magnetic properties of lithium rare-earth fluorides: Ferromagnetism in LiErF4 and LiHoF4 and crystal-field parameters at the rare-earth and Li sites

    DEFF Research Database (Denmark)

    Hansen, P. E.; Johansson, Torben; Nevald, Rolf

    1975-01-01

    was observed, but extrapolation indicates that below 0.5 K it will be ferromagnetic with the magnetic moments in the crytalline ab plane. From the susceptibilities the crystal-field parameters Bnm with (n, m)=(2, 0), (4, 0), (4, 4), (6, 0), (6, 4) have been extracted giving for Er3+ in LiErF4: 430., -985......-order crystal-field parameters at the Li site: q=0.0363, 0.0354, and 0.0343 Å-3 for the Er, Ho, and Tb compound, respectively. The crystal-field parameters are compared to values calculated from point charges, showing agreement at the Li sites but not at the rare earth sites.......Single crystals of LiErF4 and LiHoF4 have been grown and their magnetic properties measured from 1.3 K to 300 K. LiHoF4 turned out to be a nearly ideal Ising ferromagnet with TC=1.30±0.05 K and a saturation magnetization along the crystalline c axis of (6.98±0.02)μB. In LiErF4 no ordering...

  9. 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...

  10. Dynamics of domain walls with lines in rare-earth orthoferrites in magnetic and electric fields with exchange relaxation processes taken into account

    Science.gov (United States)

    Ekomasov, E. G.

    2003-08-01

    The influence of exchange relaxation on the dynamics of domain walls with a "fine structure" in rare-earth orthoferrites in the presence of external magnetic and electric fields is investigated. A system of differential equations is obtained which describe the dynamics of a domain wall with a solitary line. The dependence of the steady-state velocity of the domain wall and line on the values of the relaxation parameters and on the components of the magnetic and electric fields is found. The results are compared with the known experimental results.

  11. Magnetism of a rhombohedral-type pyrochlore-derived Kagome series, Mn2R3Sb3O14 (R = Rare-earths)

    Science.gov (United States)

    Chandragiri, Venkatesh; Iyer, Kartik K.; Maiti, K.; Sampathkumaran, E. V.

    2016-06-01

    The results of magnetic investigations on a new series of compounds, Mn2R3Sb3O14, containing 2-dimensional Kagome lattice of R ions and belonging to pyrochlore family, are presented. Crystallographic features of light R members (R = La, Pr, and Nd) of this family, as established in the recent literature, have been reported to be novel in many aspects, in particular, the rhombohedral nature of the structure which is rare among pyrochlores. It was also reported that, as the R becomes heavier, beyond R = Sm, the fraction of well-known cubic pyrochlore phase tends to gradually dominate. Here, we report that we are able to form the Gd member in the rhombohedral form without noticeable admixture from the cubic phase. With respect to magnetic behavior, our magnetization measurements on the La member reveal that Mn exists in divalent state without any evidence for long range magnetic ordering down to 2 K, a behavior (that is, suppressed magnetism) which is not so common for Mn based oxides, though antiferromagnetism below 2 K is not ruled out. Nd and Gd members are, however, found to show distinct features above 2 K in magnetic susceptibility and heat-capacity, attributable to long-range magnetic ordering from respective rare-earth sublattice. The experimental results with respect to magnetism are found to be consistent with the results from ab initio band structure calculations performed for the La case. The calculations imply that electron correlation is important to describe insulating behavior.

  12. Replacing the Rare Earth Intellectual Capital

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl

    2011-04-01

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

  13. Rare Earths; The Fraternal Fifteen (Rev.)

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl A. [Iowa State University; Ames Laboratory

    1966-01-01

    Rare earths are a set of 15 elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. They are not rare and not earths; they are metals and quite abundant. They are studied to develop commercial products which are beneficial to mankind, and because some rare earths are important to fission products.

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-01

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

  15. 2006 Rare Earth Export Quota

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ According to correlative stipulations in "Goods Import εt Export Administrating Statute of P.R.C", 2006export quota for important industrial products was issued by the Ministry of Commerce of P.R.C. on December 30th of 2005. Export quota of rare earth products is 45,000 tons. It is said the quota will be distributed in two batches. The first batch of quota will reach 70-80% of the total with 21,700 - 24,800tons for domestic companies and 10,500 - 12,000 tons for foreign invested companies. Quota will be distributed to relevant enterprises directly in recent days.

  16. Gyroscopic g factor of rare earth metals

    Science.gov (United States)

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

    2017-02-01

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

  17. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Majeed, Abdul, E-mail: abdulmajeed2276@gmail.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F. [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Akhtar, Majid Niaz [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shakir, Imran [Deanship of Scientific Research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

    2016-06-15

    Rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7–19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500–2400 cm{sup −1.} Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3b{sub VI}). The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Graphical abstract: Nano-sized rare-earth (RE=La{sup 3+}, Nd{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) doped Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route and the crystallite size was found in the range 7–19 nm. The enhancement in the coercivity was observed with the doping of rare-earth cations. The higher values of coercivity (664–926 Oe) of these nanomaterials suggest their use in longitudinal recording media. - Highlights: • Micro-emulsion route was used to synthesize Ba{sub 2}NiCoRE{sub x}Fe{sub 28−x}O{sub 46} ferrites. • The crystallite size was found

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

    Science.gov (United States)

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

    2016-11-16

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

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

    Science.gov (United States)

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

    2016-11-01

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

  20. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  1. Structure and magnetism of new rare-earth-free intermetallic compounds: Fe3+xCo3−xTi2 (0 ≤ x ≤ 3

    Directory of Open Access Journals (Sweden)

    Balamurugan Balasubramanian

    2016-11-01

    Full Text Available We report the fabrication of a set of new rare-earth-free magnetic compounds, which form the Fe3Co3Ti2-type hexagonal structure with P-6m2 symmetry. Neutron powder diffraction shows a significant Fe/Co anti-site mixing in the Fe3Co3Ti2 structure, which has a strong effect on the magnetocrystalline anisotropy as revealed by first-principle calculations. Increasing substitution of Fe atoms for Co in the Fe3Co3Ti2 lattice leads to the formation of Fe4Co2Ti2, Fe5CoTi, and Fe6Ti2 with significantly improved permanent-magnet properties. A high magnetic anisotropy (13.0 Mergs/cm3 and saturation magnetic polarization (11.4 kG are achieved at 10 K by altering the atomic arrangements and decreasing Fe/Co occupancy disorder.

  2. Calculation of the magnetic properties of pseudo-ternary R2M14B intermetallic compounds (R = rare earth, M = Fe, Co

    Directory of Open Access Journals (Sweden)

    Gabriel Gómez Eslava

    2016-06-01

    Full Text Available The extrinsic properties of NdFeB-based magnets can be tuned through partial substitution of Nd by another rare-earth element and Fe by Co, as such substitution leads to a modification in the intrinsic properties of the main phase. Optimisation of a magnet's composition through trial and error is time consuming and not straightforward, since the interplay existing between magnetocrystalline anisotropy and coercivity is not completely understood. In this paper we present a model to calculate the intrinsic magnetic properties of pseudo-ternary Nd2Fe14B-based compounds. As concrete examples, which are relevant for the optimisation of NdFeB-based high-performance magnets used in (hybrid electric vehicles and wind turbines, we consider partial substitution of Nd by Dy or Tb, and Fe by Co.

  3. Research on Rare Earth Encapsulated Luminescent Material

    Institute of Scientific and Technical Information of China (English)

    Yu Zhiwei; Liu Chengdong; Qi Xiaopeng

    2004-01-01

    A new method of preparation of irradiative material by using rare earth as luminophor and inorganic powder as base nucleus was presented.Rare earth was used to make colloid, which was mixed with base nucleus solution,where deposition/attachment reaction took place and rare earth was adhered onto the surface of base nucleus, hence yielding a new rare earth encapsulated irradiative material.Fluorescent spectrum analysis shows that this material possesses two emission peaks, one within 400 ~ 500 nm and the other within 580 ~ 700 nm, reflecting the luminous characteristics of original rare earth material.

  4. 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.

  5. Design Principle of Rare Earth-Lifting Permanent Magnetic Crane%稀土起重永磁吊的设计原理

    Institute of Scientific and Technical Information of China (English)

    丁宁; 王龙山; 何平

    2001-01-01

    通过对稀土起重永磁吊研制过程的总结和研究,系统地论述了稀土起重永磁吊的设计原理:①永磁体的回复曲线起始点应位于其退磁曲线的最大磁能积点或其下方,以提高吸重比(吸重/永磁体重量);②不同性能永磁体应与磁路结构有机配合,以降低吸重成本比(永磁体成本/吸重)。%According to the further study of the rare earth lifting permanent magnet and the summary ot the industrial prototypes, a systematic design theory has been established in this paper. Two regulations of the design of magnetic circuit are discussed, one is that the lifting permanent magnets beginning work point should lie on the point of the maximum magnetic energy product or a bit lower than that in the degenerative magnet curve, so as to raise the lifting ratio(the weight of attracted body/the weight of permanent magnetic bodies); the other is that the different performance permanent magnetic bodies should adapt to different kinds of magnetic circuits to low the cost ratio(the cost of permanent magnetic bodies/the weight of attract ed body).

  6. Electrons and Spin Waves in Heavy Rare Earth Metals

    DEFF Research Database (Denmark)

    Mackintosh, A. R.

    1972-01-01

    Although the main principles governing the magnetic interactions and magnetic ordering in rare earth metals have been qualitatively understood for some time, it is only relatively recently that a sufficiently detailed study has been made of their electronic and magnetic excitations to place this ...

  7. Magnetic and transport properties of R(Mn, In)2 (R—rare-earth metals) with AlB2-structure type

    Science.gov (United States)

    Dzevenko, M.; Havela, L.; Prokleška, J.; Svoboda, P.; Miliyanchuk, K.; Kalychak, Y.

    2007-04-01

    We studied the crystal structure and magnetic properties of ternary rare-earth R(Mn,In) 2 compounds (R=Y, La, Ce, Tb-Tm, Lu), which crystallize in the AlB 2-structure type with approximate stoichiometry RMn 0.67In 1.33, but adopting a variable Mn deficiency. YMn 0.92In 1.08 orders antiferromagnetically below TN ≈ 247 K, CeMn 0.65In 1.35 is ferromagnetic with TC=134 K. The compounds with magnetic rare earths tend to a glassy magnetic state, presumably due to the disorder in the Mn/In sublattice together with competing exchange interactions. The disorder has also a dramatic impact on the temperature dependence of the electrical resistivity, which is rather flat due to a strong scattering. The absence of long-range order was proved also by specific-heat measurements. Hydrogen absorption, tested for several compounds, led to the synthesis of LaMn 0.49In 1.51H 0.75(5).

  8. Opinions on hot discussions in connection with rare earths recently (continued)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ IV.Rare earths are mostly for civil uses Rare earth elements have excellent physical properties including optical, electric, magnetic, superconductive and catalytic performances and outstanding .chemical properties.The value of rare earths is mostly embodied in their applications.Rare earths are prepared into various advanced materials with different performances.Therefore, rare earths enjoy the reputation of "industrial monosodium glutamate" and "treasury of advanced materials".

  9. Funing Rare Earths Industrial Co. Ltd

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The company covers separation with whole lines of light, medium and heavy rare earths, with annual separation volume of rare earth oxides of 4,500 tons. It also produces rare earth oxides, fluorides and salts. Products with high-purity and super-high-purity are produced according to customer's request. Under the technological guidance of domestic experts and application of modern high-pressure

  10. 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.)

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

    Science.gov (United States)

    Takeda, Osamu; Okabe, Toru H.

    2014-06-01

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

  12. Status and development tendency of rare-earth permanent magnet materials%稀土永磁材料的现状与发展趋势

    Institute of Scientific and Technical Information of China (English)

    胡伯平

    2014-01-01

    作为稀土最重要的应用领域之一,稀土永磁材料是支撑现代社会的重要基础功能材料,与人们的生活息息相关。近10余年来,全球烧结钕铁硼磁体毛坯产量年均增长率为20%,我国年均增长率为28%;全球粘结钕铁硼磁体产量年均增长率为7%,我国年均增长率为21%。2012年,我国烧结钕铁硼磁体毛坯产量和粘结钕铁硼磁体产量分别为8.3万吨和4400吨,达到历史最高。近两年,具有高使用温度和优异耐腐蚀性的烧结钐钴磁体和热压/热变形辐射钕铁硼取向环形磁体的产量也有所增长。低碳经济对烧结钕铁硼磁体的综合磁性能指标“(BH)max (MGOe)+Hcj(kOe)”提出了越来越高的要求,目前该指标已超过70;Tb/Dy晶界扩散提高Hcj成为烧结钕铁硼的新热点,已开发出多种扩散技术并用于批量生产。利用氦气气流磨并结合无氧工艺建成的无或低Tb/Dy生产线已经在日本投入运行。粘结磁体方面,各向同性钕铁硼磁粉的国产化进程在加快,(BH)max=15MGOe的高性能磁粉已经面市,成本及耐蚀性更优的快淬Sm-Fe-N磁粉也在大力研发中;HDDR处理的各向异性钕铁硼磁粉已经商品化。高性价比的各向异性磁体成形技术正在开发,挤出成形工艺可制备直径60mm、壁厚1mm的辐射取向薄壁环。为了进一步高效利用稀土,西方国家和中国正在积极开展稀土永磁材料的回收利用。丰富的稀土资源,广阔的应用市场,稀土永磁材料将迎来更加美好的前景。%As one of the most important application for rare earth, the rare-earth permanent magnet material, which closely relates to people’s daily life, is an important fundamental functional material to support modern society. For recent ten years, the average annual growth rate of sintered Nd-Fe-B magnets output is 20% for the whole world and 28% for China. The average annual growth rate of bonded Nd

  13. 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.

  14. Magnetic properties of Kramers rare earth ions in aluminium and gallium garnets; Proprietes magnetiques des ions de kramers des terres rares dans les grenats de terres rares et d'aluminium et les grenats de terres rares et de gallium

    Energy Technology Data Exchange (ETDEWEB)

    Capel, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The magnetic properties of Kramers rare earth ions in aluminium and gallium garnets (MAlG and MGaG) are discussed by means of a molecular field treatment. The symmetry properties of the space group permit to establish a parametrization for the magnetic dipolar and exchange couplings. The magnetic properties of the system can be expressed in terms of these parameters and the g factors of the rare earth ions. We have calculated the transition temperatures, the sub-lattice magnetizations, the susceptibility in the paramagnetic region and the antiferromagnetic susceptibility for a special type of magnetic ordering. The influence of the excited Kramers doublets is described by means of a generalization of the usual g tensor. (authors) [French] Les proprietes magnetiques des ions de Kramers des terres rares dans les grenats de terre rare et d'aluminium et les grenats de terre rare et de gallium sont discutees a l'aide d'un traitement du champ moleculaire. Les proprietes de symmetrie du groupe d'espace permettent d'exprimer les couplages dipolaires et les interactions d'echange en fonction de quelques parametres. Les proprietes magnetiques peuvent etre exprimees en fonction de ces parametres et les facteurs g des ions de terre rare. Nous avons calcule les temperatures de transition, les aimantations des sous-reseaux pour 0

  15. Rare earth element enrichment using membrane based solvent extraction

    Science.gov (United States)

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

    2017-01-01

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

  16. Global rare earth resources and scenarios of future rare earth industry

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhanheng

    2011-01-01

    It is known to all that China is abundant in rare earth resources. But rare earth deposits are really not that rare in the earth crust. In the five continents, i.e. Asia, Europe, Australia, North and South America, and Africa, there are about thirty four countries found to have rare earth deposits; Brazil might surpass China and rank the first in rare earth deposits. At present, investment in rare earth production was surged,there have been about 200 projects, and the total production for 25 of them would be more than 170 thousand tons after 2015, a multi-supply system on rare earths is being established worldwide. Cautions on the investment of rare earth production are involved.

  17. Application progress of rare earth nano-materials

    Institute of Scientific and Technical Information of China (English)

    Xiao Zhe

    2009-01-01

    @@ Total rare earth consumption exceeded 72,600 tREO domestically in China in 2007, among which over 38,500 tREO were consumed in functional materials like permanent magnetic materials, fluorescent materials, hydrogen storage materials, catalytic materials and polishing powders,representing 53% of total RE consumption. Production and application of RE performance materials have been the main force promoting the development of China rare earth industry.

  18. Imports (&) Exports Review of Chinese Rare Earths (continued)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Since 2001, China kept its position of the largest producing country of rare earth magnets in the world and worked on further in the global market. China exported 7,709 tons of rare earth magnets and earned foreign currency of US $ 214 million in 2004, increasing 37.2% and 33.0% over the same period of 2003 respectively. In 2005, China exported 8,756 tons of RE magnets and earned foreign currency of US $ 239 million, up 13.9% and 11.4% over 2004 respectively. The first six export destinations are listed in Table 3.

  19. Rare earth elements and strategic mineral policy

    NARCIS (Netherlands)

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

    2010-01-01

    Newspapers report almost daily on international tensions around ‘strategic’ or ‘critical’ minerals such as rare earth elements. The temporary freeze of rare earth exports from China to Japan in late 2010 in retaliation of the capture of a Chinese captain is but one example of the strategic use of no

  20. Rare-earth magnetism in cuprates with T[sup prime-]structure. [GdPrCuO; GdNdCuO; GdSmCuO; GdEuCuO

    Energy Technology Data Exchange (ETDEWEB)

    Czjzek, G. (Kernforschungszentrum Karlsruhe, INFP and ITP, P.O. Box 3640, W-7500 Karlsruhe 1 (Germany)); Roth, G. (Kernforschungszentrum Karlsruhe, INFP and ITP, P.O. Box 3640, W-7500 Karlsruhe 1 (Germany)); Kroener, T. (Kernforschungszentrum Karlsruhe, INFP and ITP, P.O. Box 3640, W-7500 Karlsruhe 1 (Germany)); Adelmann, P. (Kernforschungszentrum Karlsruhe, INFP and ITP, P.O. Box 3640, W-7500 Karlsruhe 1 (Germany))

    1994-04-01

    Cuprates of composition (Gd[sub 1-x]R[sub x])[sub 2]CuO[sub 4], R=Pr, Nd, Sm, Eu, have been studied by [sup 155]Gd Moessbauer spectroscopy and by complementary experimental techniques. The results provide new evidence for the important influence of exchange interactions between Cu and rare-earth 4f-moments on rare-earth magnetism in these compounds. ((orig.))

  1. Chinalco Rare Earth has Surpassed Ganzhou to Become the Biggest Giant in South China Rare Earth

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    As the pillar enterprise in Chinalco rare earth unit,Chinalco Guangxi Rare Earth Company firmly grasped the historical opportunity of the state government supporting six big groups including Chinalco to integrate and develop domestic rare earth enterprises,riding the east wind to stand out,recently,it made significant

  2. 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.

  3. Theoretical and experimental study of high-magnetic-field XMCD spectra at the L2,3 absorption edges of mixed-valence rare-earth compounds

    Science.gov (United States)

    Kotani, Akio; Matsuda, Yasuhiro H.; Nojiri, Hiroyuki

    2009-11-01

    X-ray magnetic circular dichroism(XMCD) spectra at the L2,3 edges of mixed-valence rare-earth compounds in high magnetic fields are studied both theoretically and experimentally. The theoretical study is based on a new framework proposed recently by Kotani. The Zeeman splitting of 4f states, the mixed-valence character of 4f states, and the 4f-5d exchange interaction are incorporated into a single impurity Anderson model. New XMCD experiments in high magnetic fields up to 40 T are carried out for the mixed-valence compounds EuNi2(Si0.18Ge0.82)2 and YbInCu4 by using a miniature pulsed magnet, which was developed recently by Matsuda et al. The XMCD data are taken at 5 K by transmission measurements for incident X-rays with ± helicities at BL39XU in SPring-8. After giving a survey on recent developments in the theory of XMCD spectra for mixed-valence Ce and Yb compounds, we calculate the XMCD spectra of YbInCu4 at the field-induced valence transition around 32 T by applying the recent theoretical framework and by newly introducing at 32 T a discontinuous change in the Yb 4f level and that in the hybridization strength between the Yb 4f and conduction electrons. The calculated results are compared with the experimental ones.

  4. Effect of microstructure and texture on the magnetic and magnetocaloric properties of the melt-spun rare earth intermetallic compound DyNi

    Science.gov (United States)

    Rajivgandhi, R.; Chelvane, J. Arout; Nigam, A. K.; Park, Je-Geun; Malik, S. K.; Nirmala, R.

    2016-11-01

    Magnetization measurements have been carried out on the melt-spun ribbon sample of the rare earth intermetallic compound DyNi (Orthorhombic, FeB-type, Space group Pnma) and its magnetic and magnetocaloric properties are compared with those of the arc-melted analog. The arc-melted DyNi orders ferromagnetically at around 61 K (TC) whereas the melt-spun DyNi orders ferromagnetically at about 47 K. The maximum isothermal magnetic entropy change, ∆Smmax , near TC of the arc-melted and the melt-spun DyNi is found to be -32.7 J/kg K and -22.4 J/kg K, respectively, for a field change of 140 kOe. For low magnetic field changes of ~20 kOe, the relative cooling power (RCP) is ~660 J/kg for the arc melted DyNi and ~460 J/kg for the melt-spun ribbon. The reduction in TC and magnetocaloric effect may be attributed to the microstructure-induced anisotropy developed during the melt-spinning process.

  5. Solar Energy Cell with Rare Earth Film

    Institute of Scientific and Technical Information of China (English)

    Li Baojun; Yang Tao; Zhou Yao; Zhou Meng; Fu Xiliang; Fu Li

    2004-01-01

    The characteristic of the solar energy cell with the rare earth film according to theory of molecular structure was introduced.When sunlight shines, the molecules of the rare earth film can absorb energy of the photon and jump to the excited state from the basic state, and play a role in storing solar energy.When sunlight do not shine, the electron of the excited state returns to the basic state, the rare earth film can automatically give out light and shine to surface of the solar cell, which can make solar cell continuously generate electric current.The rare earth film can absorb direct,scattering sunlight, and increase density of solar energy to reach surface of the solar cell, and play focusing function.The rare earth film can bear 350 ~ 500 ℃, which make the solar cell be able to utilize the focusing function system.Because after luminescence of the rare earth film, it can release again the absorbed solar energy through 1 ~ 8 h, and play a role in storing solar energy; The solar cell with the rare-earth film can generate electricity during night and cloudy days, and remarkably increase efficiency of the solar cell.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang

    2013-10-16

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

  7. Recycling as a strategy against rare earth element criticality: a systemic evaluation of the potential yield of NdFeB magnet recycling.

    Science.gov (United States)

    Rademaker, Jelle H; Kleijn, René; Yang, Yongxiang

    2013-09-17

    End-of-life recycling is promoted by OECD countries as a promising strategy in the current global supply crisis surrounding rare earth elements (REEs) so that dependence on China, the dominant supplier, can be decreased. So far the feasibility and potential yield of REE recycling has not been systematically evaluated. This paper estimates the annual waste flows of neodymium and dysprosium from permanent magnets, the main deployment of these critical REEs, during the 2011-2030 period. The estimates focus on three key permanent magnet waste flows: wind turbines, hybrid and electric vehicles, and hard disk drives (HDDs) in personal computers (PCs). This is a good indication of the end-of-life recycling of neodymium and dysprosium maximum potential yield. Results show that for some time to come, waste flows from permanent magnets will remain small relative to the rapidly growing global REE demand. Policymakers therefore need to be aware that during the next decade recycling is unlikely to substantially contribute to global REE supply security. In the long term, waste flows will increase sharply and will meet a substantial part of the total demand for these metals. Future REE recycling efforts should, therefore, focus on the development of recycling technology and infrastructure.

  8. Density functional theory study of the magnetic properties of rare earth complexes:the magnetic coupling mechanism in Y~Ⅲ and Gd~Ⅲ complexes with nitronyl nitroxide

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The magnetic coupling interactions of the nitronyl nitroxide radicals bound to diamagnetic(YⅢ) and paramagnetic(GdⅢ) rare earth ions in two model magnetic systems based on novel rare earth organic radical complexes Ln(hfac)3(NITPhOCH3)2(Ln=YⅢ 1,GdⅢ 2;hafc = hexafluoroacetylacetonate;NIT-PhOCH3 = 4’-methoxyo-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been investigated by density functional theory(DFT).The magnetic coupling mechanisms were also explored from the viewpoint of molecular orbital and spin density populations.DFT calculations show that the empty 4d-orbitals of YⅢ and 5d-orbitals of GdⅢ play an important role in the antiferromagnetic coupling between the two nitronyl nitroxide radical ligands,and that the ferromagnetic coupling between the GdⅢ ion and the radical magnetic centers can be attributed to the nearly complete localization of the isotropic 4f-shell and singly occupied magnetic orbital(π) of the nitronyl nitroxide.

  9. Density functional theory study of the magnetic properties of rare earth complexes:the magnetic coupling mechanism in Y~Ⅲ and Gd~Ⅲ complexes with nitronyl nitroxide

    Institute of Scientific and Technical Information of China (English)

    REN Jie; WANG BingWu; CHEN ZhiDa

    2009-01-01

    The magnetic coupling interactions of the nitronyl nitroxide radicals bound to diamagnetic (Y~Ⅲ) and paramagnetic (Gd~Ⅲ) rare earth ions in two model magnetic systems based on novel rare earth organic radical complexes Ln(hfac)_3(NITPhOCH_3)_2 (Ln=Y~Ⅲ 1,Gd~Ⅲ 2;hafc=hexafluoroacetylacetonate;NITPhOCH_3=4'-methoxyo-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been investigated by density functional theory (DFT).The magnetic coupling mechanisms were also explored from the viewpoint of molecular orbital and spin density populations.DFT calculations show that the empty 4d-orbitals of Y~Ⅲ and 5d-orbitals of Gd~Ⅲ play an important role in the antiferromagnetic coupling between the two nitronyl nitroxide radical ligands,and that the ferromagnetic coupling between the Gd~Ⅲ ion and the radical magnetic centers can be attributed to the nearly complete localization of the isotropic 4f-shell and singly occupied magnetic orbital (Π*) of the nitronyl nitroxide.

  10. Rare earth element mines, deposits, and occurrences

    Data.gov (United States)

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

  11. China Not the Only Rare Earth Exporter

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Since China announced it was reducing exports of rare earth,there have been continuous voices in the international community demanding China expand exports or seek alternative resources. The United States has also complained to the WTO that China is hoarding the commodity. Subjected to scathing censure,what difficulties are facing China’s rare earth industry? When other countries seek alternative resources,how is the Chinese rare earth market affected? Economy&Nation Weekly,Xinhua News Agency’s finance magazine,recently interviewed Lin Donglu,Secretary General of the Chinese Society of Rare Earths,and Wang Hongqian, General Manager of China Non-Ferrous Metal Industry’s Foreign Engineering and Construction Co.Ltd.Edited excerpts follow

  12. 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

  13. 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."

  14. Ternary rare earth-lanthanide sulfides

    Science.gov (United States)

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

    1987-01-06

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

  15. Partitioning properties of rare earth ores in China

    Institute of Scientific and Technical Information of China (English)

    CHI Ru'an; LI Zhongjun; PENG Cui; ZHU Guocai; XU Shengming

    2005-01-01

    The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, and the weathering crust type. Both the Bayan Obo rare earth ore and the Zhushan rare earth ore are a kind of mixed ore, consisting of bastnaesite and monazite. Their rare earth partitionings are strongly enriched in light rare earths, where CeO2 is 50% and the light rare earth partitioning is totally over 95%. The Mianning rare earth ore as well as the Weishan rare earth is a kind of rare earth ore only having bastnaesite. Their rare earth partitionings are also strongly enriched in light rare earths,in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rare earth ore,there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Longnan rare earth ore, which is strongly enriched in heavy rare earths, Y2O3 is 64.83%, and the heavy and light rare earth partitionings are 89.40% and 10.53%, respectively. In the Xunwu rare earth ore, which is strongly enriched in light rare earths, CeO2 is 47.16%, and the light rare earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttrium and rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%,respectively, which are mainly industrial resources of the middle and the heavy rare earths.

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

    Science.gov (United States)

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

    2016-08-01

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

  17. Large magnetic entropy change and relative cooling power in the rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Rajib [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082 -970 (Brazil)

    2015-11-01

    Magnetic and magnetocaloric properties of cubic Laves phase rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound have been investigated. Magnetization measurements show that HoCo{sub 0.25}Ni{sub 1.75} orders ferromagnetically at 22 K (T{sub C}). The magnetization vs field (M–μ{sub 0}H) isotherm at 2 K shows negligible hysteresis. The isothermal magnetic entropy change (ΔS{sub m}) is calculated from the measured M–µ{sub 0}H data near T{sub C.} The maximum value of ΔS{sub m}, ΔS{sub m}{sup max}, is about −18.9 J/kg-K at T{sub C} for a field change of 5 T with a refrigerant capacity of 572 J/kg. The material exhibits large ΔS{sub m}{sup max} of −9.4 J/kg-K even for a low field change of 2 T. Universal master curve is constructed by rescaling ΔS{sub m} vs T curves for various fields to confirm the second order nature of the magnetic transition at T{sub C}. Large ΔS{sub m}{sup max} value, wide temperature span of cooling and high relative cooling power make HoCo{sub 0.25}Ni{sub 1.75} a potential magnetic refrigerant for low temperature applications such as hydrogen liquefaction. - Highlights: • A large magnetocaloric effect is observed in Laves phase HoCo{sub 0.25}Ni{sub 1.75} compound. • The isothermal magnetic entropy change ΔS{sub m} vs T of HoCo{sub 0.25}Ni{sub 1.75} is broad near T{sub C}. • The magnetization vs field isotherms have negligible hysteresis. • A large relative cooling power is realized in HoCo{sub 0.25}Ni{sub 1.75}. • Universal master curve is constructed by rescaling ΔS{sub m} vs T data.

  18. Influence of processing on structure property correlations in τ-MnAl rare-earth free permanent magnet material

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Nidhi; Mudgil, Varun; Anand, Kanika; Srivastava, A.K.; Kotnala, R.K.; Dhar, Ajay, E-mail: adhar@nplindia.org

    2015-06-05

    Highlights: • The reported magnetic properties of τ-MnAl show a significant scatter in their data. • We report the synthesis of τ-MnAl employing different processing routes. • The observed magnetic properties were correlated with the synthesis route. • The resulting microstructure has been correlated with the magnetic properties. - Abstract: In order to understand the genesis of the magnetic τ-phase of MnAl alloy, which due to its multiphase nature is generally difficult to synthesize as a single-phase, we have synthesized it employing three different materials processing routes, namely, arc melting, mechanical alloying, and a combination of these two. Structural and microstructural characterizations employing X-ray diffraction and high resolution transmission electron microscopy demonstrate that irrespective of the material processing route employed, the formation of τ-MnAl phase was always accompanied by other non-magnetic phases, e.g., β-MnAl and γ-MnAl. However, the relative fraction of these phases was found to be dependent on the materials processing route and hence on the grain size of the parent phase. The arc melted alloy had the largest grain size and the highest fraction of the τ-MnAl phase, while the alloy prepared by mechanical alloying showed the smallest grain size and the lowest fraction of the magnetic phase. The largest value of Curie temperature, magnetic moment, coercivity and remanence were observed in the sample prepared by a combination of arc melting and mechanical alloying. Our results suggest that in addition to the τ-MnAl phase fraction the magnetic properties could be related to the density of structural defects.

  19. Study of the hyperfine magnetic field acting on Ce probes substituting for the rare earth and the magnetic ordering in intermetallic compounds RAg (R=rare earth) by first principles calculations; Estudo do campo hiperfino magnetico na sonda de Ce colocada nos compostos intermetalicos do tipo RAg (R=terra rara) e do ordenamento magnetico desses compostos usando calculos de primeiros principios

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Luciano Fabricio Dias

    2006-07-01

    In this work the magnetic hyperfine field acting on Ce atoms substituting the rare-earths in R Ag compounds (R = Gd e Nd) was studied by means of first-principles electronic structure calculations. The employed method was the Augmented Plane Waves plus local orbitals (APW+lo), embodied in the WIEN2k program, within the framework of the Density Functional Theory (DFT) and with the Generalized Gradient Approximation (GGA) for the exchange and correlation potential. The super-cell approach was utilized in order to simulate for the Ce atoms acting as impurities in the R Ag matrix. In order to improve for correlation effects within the 4f shells, a Hubbard term was added to the DFT Hamiltonian, within a procedure called GGA+U. It was found that the magnetic hyperfine field (MHF) generated by the Ce 4f electron is the main component of the total MHF and that the Ce 4f ground state level is probably a combination of the m{sub l} = -2 and m{sub l} = -1 sub-levels. In addition, the ground-state magnetic structure was determined for Ho Ag and Nd Ag by observing the behavior of the total energy as a function of the lattice volume for several possible magnetic ordering in these compounds, namely, ferromagnetic, and the (0,0,{pi}), ({pi},{pi},0) and (({pi},{pi},{pi}) types of anti-ferromagnetic ordering of rare-earth atoms. It was found that the ground-state magnetic structure is anti-ferromagnetic of type ({pi},{pi},0) for both, the Ho Ag and Nd Ag compounds. The energy difference of the ferromagnetic and antiferromagnetic ordering is very small in the case of the Nd Ag compound. (author)

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

    Institute of Scientific and Technical Information of China (English)

    HU YUE

    2011-01-01

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

  1. Rare earth elements. A new approach to the nexus of supply, demand and use. Exemplified along the use of neodymium in permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Zepf, Volker

    2013-02-01

    This thesis deals with Rare Earth Elements (REE), especially with neodymium used in permanent magnets, from a very scientific basis by providing basic research data. Despite the fact that REE are newsworthy and very important elements for a considerable bandwidth of todays' technologies, accompanied by the monopolistic supply-situation and Chinese politics, there are inexplicable data discrepancies about REE which have been recognized frequently but usually have not been addressed accordingly. So this analysis started with the hypothesis that the four application areas, namely computer hard disk drives (HDD), mobile phones, wind turbines and e-mobility (automotive traction), account for about 80% of the global annual neodymium-demand. The research methodology was a laboratory analysis of the composition of used magnets for HDDs and mobile phones and a literature and official report analysis of wind turbine and automotive neodymium use. The result was amazing and the hypothesis had to be withdrawn as these four areas only account for about 20% of neodymium use. This result raises some questions concerning actual use and thus potential recycling options.

  2. Theoretical and Computational Studies of Rare Earth Substitutes: A Test-bed for Accelerated Materials Development

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, Lorin X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    Hard permanent magnets in wide use typically involve expensive Rare Earth elements. In this effort, we investigated candidate permanent magnet materials which contain no Rare Earths, while simultaneously exploring improvements in theoretical methodology which enable the better prediction of magnetic properties relevant for the future design and optimization of permanent magnets. This included a detailed study of magnetocrystalline anisotropy energies, and the use of advanced simulation tools to better describe magnetic properties at elevated temperatures.

  3. MgZn2-type {Ho, Er, Tm}FeGa rare earth compounds: Crystal structure and magnetic properties

    Science.gov (United States)

    Morozkin, A. V.; Genchel, V. K.; Garshev, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2017-09-01

    The crystal structure of new hexagonal MgZn2-type {Ho, Tm}FeGa compounds (space group P63/mmc, N 194, hP12) has been established using powder X-ray diffraction studies. The magnetic properties of polycrystalline MgZn2-type ErFeGa compound have been studied using bulk magnetization data. ErFeGa exhibits ferromagnetic ordering at TC = 77 K and field sensitive antiferromagnetic-like ordering at Tm 58 K in field of 100 Oe and Tm 10 K in field of 5 kOe. The paramagnetic susceptibility follows Curie-Weiss law with effective paramagnetic moment per formula unit (Meff/fu) of 9.59 μB and paramagnetic Weiss temperature (ΘP) of 27 K. At 2 K, ErFeGa exhibits hard magnetic properties with remanent magnetization per formula unit (Mres/fu) of 3.7 μB, coercive field (Hcoer) of 8.2 kOe and critical field (Hcrit) of 9.6 kOe. The magnetocaloric effect of ErFeGa has been calculated in terms of isothermal magnetic entropy change (ΔSm) and maximum ΔSm values are -5.5 J/kg K for a field change of 0-50 kOe (relative cooling power RCP50 kOe 410 J/kg), -13.0 J/kg K for a field change of 0-140 kOe (RCP140 kOe 1230 J/kg) at 70 K and +1.7 J/kg K for a field change of 0-10 kOe at 10 K (RCP10 kOe 34 J/kg).

  4. [mu]SR magnetic response in frustrated antiferromagnets of type RMn[sub 2] (R = rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M. (Physics Dept., TU Munich, Garching (Germany)); Asch, L. (Physics Dept., TU Munich, Garching (Germany)); Kratzer, A. (Physics Dept., TU Munich, Garching (Germany)); Kalvius, G.M. (Physics Dept., TU Munich, Garching (Germany)); Muench, K.H. (Physics Dept., TU Munich, Garching (Germany)); Ballou, R. (Lab. Louis Neel, CNRS, 38 Grenoble (France)); Deportes, J. (Lab. Louis Neel, CNRS, 38 Grenoble (France)); Waeppling, R. (Dept. of Physics, Univ. of Uppsala (Sweden)); Litterst, F.J. (Inst. for Metal Physics, TU Braunschweig (Germany)); Klauss, H.H. (Inst. for Metal Physics, TU Braunschweig (Germany)); Niedermayer, C. (Faculty for Physics, Univ. Konstanz (Germany)); Chappert, J. (CEA/DRFMC, CEN Grenoble, 38 (France))

    1994-07-01

    Zero, longitudinal and transverse field [mu]SR was carried out in the antiferromagnets YMn[sub 2], Y[sub 0.95] Tb[sub 0.15] Mn[sub 2], Y[sub 0.9]Tb[sub 0.1]Mn[sub 2], Y[sub 0.99] Sc[sub 0.01] Mn[sub 2], Y[sub 0.98]Sc[sub 0.02]Mn[sub 2] and TbMn[sub 2]. The dynamics of Mn magnetic moments above T[sub N] is typical for an itinerant antiferromagnet. Within a certain temperature range above T[sub N] part of the material enters a randomly ordered (spin glass like) magnetic state as an out-come of frustration. At temperatures above [approx] 150 K the muon spin relaxation rate indicates that the muon has become mobile. (orig.)

  5. Structural disorder and magnetism in rare-earth (R) R117Co54+xSn112±y

    Energy Technology Data Exchange (ETDEWEB)

    Mudryk, Y.; Manfrinetti, P.; Smetana, V.; Liu, J.; Fornasini, M. L.; Provino, A.; Pecharsky, V. K.; Miller, G. J.; Gschneidner, K. A.

    2013-04-01

    The cubic R117Co54+xSn112±y compounds (R = La–Lu, except Pm, Eu, and Yb) have been synthesized and characterized using X-ray diffraction and magnetization measurements. The existence of the compounds with R = Ce, Pr, Sm, Gd, Tb, and Dy has been confirmed, while new compounds with R = Y, La, Nd, Ho, Er, Tm, and Lu have been discovered. All of the studied phases adopt the Dy117Co57Sn112-type crystal structures with a giant cubic cell (a ~ 30 Å) when the proper heat treatment regime was selected. The lattice parameter decreases from La to Lu, in accordance with the lanthanide contraction and indicating the trivalent state for Ce in Ce117Co54.5Sn115.2. The Co/Sn compositional ratio increases when the size of the R atoms decreases. A single crystal investigation of Gd117Co56.4Sn114.3 confirms extensive structural disorder, particularly around the (1/2, 1/2, 1/2) location of the unit cell (4b site). Such disorder leads to an elongation of the thermal ellipsoids for the atoms surrounding this location. The magnetic measurements of the compounds with R = Ce, Gd and Tb indicate weak magnetic interactions and non-collinear alignment of magnetic moments in the ordered state. The electrical resistivity of Gd117Co56.4Sn114.3 shows interesting behavior with a change of sign at TC for the dρ/dT parameter.

  6. Improvement of the magnetic properties for Mn–Ni–Zn ferrites by rare earth Nd3+ ion substitution

    Directory of Open Access Journals (Sweden)

    M.M. Eltabey

    2014-09-01

    Full Text Available Single spinel phases of Mn0.5Ni0.1Zn0.4NdxFe2−xO4 ferrite samples (x = 0.0, 0.01, 0.02, 0.05, 0.075, and 0.1 have been prepared by ceramic method and the composition dependence of the physical and magnetic properties has been investigated. SEM micrographs and EDX analysis revealed that there is no considerable effect for the Nd3+ ion substitution on the average grain size or porosity, whereas its concentration in the grain boundaries is higher than that in the grains. Saturation magnetization (MS increased with the Nd3+ ion concentration (x and reached a maximum value at x = 0.05. In addition, both the initial permeability and the magnetic homogeneity increased by increasing the Nd3+ ion content. The value of Curie temperature increased due to the substitution by Nd3+ ions to record about 170 K, for the sample with x = 0.05, higher than that of the un-substituted one.

  7. Structural, electrical and magnetic properties of rare-earth and transition element co-doped bismuth ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Vivek, E-mail: vermavivek.neel@gmail.com

    2015-08-25

    Highlights: • Sm-doping increases the symmetry and decreases the second phase formation. • Ferromagnetic, ferroelectric and dielectric properties enhanced with doping. • M–H loops represents weak ferromagnetic (FM) behavior. • A modification in dielectric constant is observed due to doping of Mn, Co and Cr. • Saturation polarization (P{sub s}), remnant polarization (P{sub r}) and coercive field (E{sub c}) increased with doping. - Abstract: Pure and doped multiferroic samples of bismuth ferrites (BFO) were successfully synthesized by the sol–gel technique. Detailed investigations were made on the influence of (Sm and Mn, Co, Cr) co-doping on structural, electrical, ferroelectric and magnetic properties of the BFO. A structural phase transformation from rhombohedral to orthorhombic with co-doping is confirmed through XRD. It is also observed that Sm-doping increases the symmetry and decreases the second phases noticeably. Microstructure investigation using the scanning electron microscope showed a reduction of grain size with doping in BFO. Magnetic hysteresis loops showed that retentivity (Mr), coercivity (Hc) and saturation magnetization (Ms) of the doped samples were improved. Furthermore, the co-doping enhances the dielectric properties as a result of the reduction in the Fe{sup 2+} ions and oxygen vacancies. The room temperature P–E loop study shows that ferroelectric properties are strongly depend on doping.

  8. 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.

  9. Microwave studies on double rare earth oxalate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Elizabeth, Anit [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Joseph, Cyriac [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Paul, Issac [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Ittyachen, M.A. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam 686560 (India); Mathew, K.T. [Microwave Imaging and Material Research Laboratory, Department of Electronics, Cochin University of Science and Technology, Kochi 682022 (India)]. E-mail: ktm@cusat.ac.in; Lonappan, Anil [Microwave Imaging and Material Research Laboratory, Department of Electronics, Cochin University of Science and Technology, Kochi 682022 (India); Jacob, Joe [Microwave Imaging and Material Research Laboratory, Department of Electronics, Cochin University of Science and Technology, Kochi 682022 (India)

    2005-01-25

    Rare earth compounds are recognized for outstanding physical, magnetic and optical properties. The oxalates and molybdates have gained importance for their various properties, which find applications in electro and accusto optical devices. This paper reports the microwave dielectric studies on double rare earth oxalate crystals. Using the cavity perturbation technique dielectric parameters such as complex permittivity and conductivity at microwave frequencies is determined. Using X-ray diffraction study the crystalline nature of the samples was established. The molecular and crystal structures were identified by IR analysis.

  10. Interaction domains in permanent-magnetic rare-earth transition-metal compounds; Wechselwirkungsdomaenen in permanentmagnetischen Seltenerd-Uebergangsmetall-Verbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Thielsch, Juliane

    2015-02-05

    In the framework of this dissertation the phenomenon of the interaction domains was studied both experimentally and by means of micromagnetic simulation. Object of the study were one-phase NdFeB magnets, which were fabricated from commercial MQU-F powders of the Magnequench Inc. company by hot pressing and subsequent warm deformation in the IWF Dresden. Additionally via the same fabrication way also composite samples of NdFeB and Fe with different original particle sizes ere obtained and studied. Supported wer the experimental works by simulations with the FEMME software package, which is based on a hybrid finite-element method/boundary-element method.

  11. Earth magnetism a guided tour through magnetic fields

    CERN Document Server

    Campbell, Wallace H

    2001-01-01

    An introductory guide to global magnetic field properties, Earth Magnetism addresses, in non-technical prose, many of the frequently asked questions about Earth''s magnetic field. Magnetism surrounds and penetrates our Earth in ways basic science courses can rarely address. It affects navigation, communication, and even the growth of crystals. As we observe and experience an 11-year solar maximum, we may witness spectacular satellite-destroying solar storms as they interact with our magnetic field. Written by an acknowledged expert in the field, this book will enrich courses in earth science, atmospheric science, geology, meteorology, geomagnetism, and geophysics. Contains nearly 200 original illustrations and eight pages of full-color plates.* Largely mathematics-free and with a wide breadth of material suitable for general readers* Integrates material from geomagnetism, paleomagnetism, and solar-terrestrial space physics.* Features nearly 200 original illustrations and 4 pages of colour plates

  12. Analytical results for crystalline electric field eigenvalues of trivalent rare-earth ions using computer algebra: application to the magnetism of PrX2 ( X = Mg, Al, Ru, Rh, Pt)

    Science.gov (United States)

    Sobral, R. R.; Guimarães, A. P.; da Silva, X. A.

    1994-10-01

    The eigenvalues of the Crystalline Electric Field (CEF) Hamiltonian with cubic symmetry are analytically obtained for trivalent rare-earth ions of ground state J= {5}/{2}, {7}/{2}, 4, {9}/{2}, 6, {15}/{2} and 8, via a Computer Algebra approach. In the presence of both CEF and an effective exchange field, Computer Algebra still allows a partial factorization of the characteristic polynomial equation associated to the total Hamiltonian, a result of interest to the study of the magnetic behavior of rare-earth intermetallics. An application to the PrX2 intermetallic compounds ( X = Mg, Al, Ru, Rh, Pt) is reported.

  13. Magnesium substitutions in rare-earth metal germanides with the Gd5Si4 type. Synthesis, structure determination and magnetic properties of RE5-xMgxGe4 (RE=Gd-Tm, Lu and Y)

    Energy Technology Data Exchange (ETDEWEB)

    Sarrao, J L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Tobash, P H [UNIV. OF DE; Bobev, S [UNIV. OF DE

    2009-01-01

    A series of magnesium-substituted rare-earth metal germanides with a general formula RE{sub 5-x}Mg{sub x}Ge{sub 4} (x {approx} 1.0-2.3; RE =Gd-Tm, Lu, Y) have been synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. These compounds crystallize with the common Gd{sub 5}Si{sub 4} type in the orthorhombic space group Pnma (No. 62; Z =4; Pearson's code oP36) and do not appear to undergo temperature-induced crystallographic phase transitions down to 120 K. Replacing rare-earth metal atoms with Mg, up to nearly 45 % at., reduces the valence electron count and is clearly expressed in the subtle changes of the Ge-Ge and metal-metal bonding. Magnetization measurements as a function of the temperature and the applied field reveal complex magnetic structures at cryogenic temperatures, and Curie-Weiss paramagnetic behavior at higher temperatures. The observed local moment magnetism is consistent with RE+ ground states in all cases. In the magnetically ordered phases, the magnetization cannot reach saturation in fields up to 50 kOe. The structural trends across the series and the variations of hte magnetic properties as a function of the Mg content are also discussed. KEYWORDS: Rare-earth intermetallics, germanides, crystal structure,Gd{sub 5}Si{sub 4} type.

  14. A novel contrast agent with rare earth-doped up-conversion luminescence and Gd-DTPA magnetic resonance properties

    Science.gov (United States)

    Lu, Qing; Wei, Daixu; Cheng, Jiejun; Xu, Jianrong; Zhu, Jun

    2012-08-01

    The magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF4:Yb, Er were successfully synthesized by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF4:Yb, Er nanoparticles through EDC/NHS coupling chemistry. The as-prepared products were characterized by powder X-ray diffraction, transmission electron microscopy, dynamic light scattering, energy dispersive X-ray analysis, and fourier transform infrared spectrometry. The room-temperature upconversion luminescent spectra and T1-weighted maps of the obtained nanoparticles were carried out by 980 nm NIR light excitation and a 3T MR imaging scanner, respectively. The results indicated that the as-synthesized multifunctional nanoparticles with small size, highly solubility in water, and both high MR relaxivities and upconversion luminescence may have potential usage for MR imaging in future.

  15. Method for treating rare earth-transition metal scrap

    Science.gov (United States)

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

    1992-12-29

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

  16. 2011 Review and outlook of China rare earth market

    Institute of Scientific and Technical Information of China (English)

    Zhang Lihua; Bai Jinlong

    2012-01-01

    In 2011, the start year of the "Twelfth-Five Year Plan" program, a series of policies were issued targeting on rare earth industry. Price of rare earths fluctuated sharply during 2011 and consumers were concerned about the supply of rare earth. There was a big change in rare earth industry.

  17. 2007 China Rare Earths Import & Export Analysis and Suggestions (continued)

    Institute of Scientific and Technical Information of China (English)

    Yin Jianhua; Zuo Xichao

    2008-01-01

    @@ 4. Increasing import of rare earth resources products As a big producer and an important export country of rare earth products for years, rare earths import is in an auxiliary position in China. import volume is rather small. However, since the strengthened macro control measures and restriction of mining scale in 2007, domestic rare earth supply was tight in China.

  18. Prices of Rare Earth Products Tend to Rise(Continued)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    8. Ji Daiyu, General Manager of Baotou Xinyuan RareEarth Hi-Tech Materials Co. LtdControl gross to stabilize prices. Chinese rare earth is precious strategic resource. The more it is exploit, the less it will be. The State has put forward rare earth policy of "strengthen management, protect resource, develop scientifically and face international". Chinese rare earth

  19. Supramolecular Assembly of Molecular Rare-Earth-3,5-Dichlorobenzoic Acid-2,2':6',2″-Terpyridine Materials: Structural Systematics, Luminescence Properties, and Magnetic Behavior.

    Science.gov (United States)

    Carter, Korey P; Thomas, Kara E; Pope, Simon J A; Holmberg, Rebecca J; Butcher, Ray J; Murugesu, Muralee; Cahill, Christopher L

    2016-07-18

    The syntheses and crystal structures of 16 new rare-earth (RE = La(3+)-Y(3+))-3,5-dichlorobenzoic acid-terpyridine molecular materials characterized via single-crystal and powder X-ray diffraction are reported. These 16 complexes consist of four unique structure types ranging from molecular dimers (La(3+) and Ce(3+)) to tetramers (Pr(3+)-Y(3+)) as one moves across the RE(3+) series. This structural evolution is accompanied by subsequent changes in modes of supramolecular assembly (halogen bonding, halogen-π, halogen-halogen, and π-π interactions). Solid-state visible and near-infrared lifetime measurements were performed on complexes 6 (Sm(3+)), 7 (Eu(3+)), 9 (Tb(3+)), 10 (Dy(3+)), 11 (Ho(3+)), 12 (Er(3+)), and 14 (Yb(3+)), and characteristic emission was observed for all complexes except 11. Lifetime data for 11, 12, and 14 suggest sensitization by the terpy antenna does occur in near-infrared systems, although not as efficiently as in the visible region. Additionally, direct current magnetic susceptibility measurements were taken for complexes 10 (Dy(3+)) and 12 (Er(3+)) and showed dominant ferromagnetic behavior.

  20. Flux Synthesis, Crystal Structures, and Magnetic Ordering of the Rare-Earth Chromium(II) Oxyselenides RE2CrSe2O2 (RE = La-Nd).

    Science.gov (United States)

    Peschke, Simon; Weippert, Valentin; Senyshyn, Anatoliy; Mühlbauer, Martin Johann; Janka, Oliver; Pöttgen, Rainer; Holenstein, Stefan; Luetkens, Hubertus; Johrendt, Dirk

    2017-02-20

    The rare-earth chromium(II) oxyselenides RE2CrSe2O2 (RE = La-Nd) were synthesized in eutectic NaI/KI fluxes, and their crystal structures were determined by single-crystal and powder X-ray diffraction (Pb2HgCl2O2-type, C2/m, Z = 2). The magnetic structure of La2CrSe2O2 was solved and refined from neutron powder diffraction data. Main building blocks are chains of edge-sharing CrSe4O2 octahedra linked together by two edge-sharing ORE3Cr tetrahedra forming infinite ribbons. The Jahn-Teller instability of divalent Cr(2+) (d(4)) leads to structural phase transitions at 200 and 130 K in La2CrSe2O2 and Ce2CrSe2O2, respectively. RE2CrSe2O2 are Curie-Weiss paramagnetic above TN ≈ 14-17 K. Neutron powder diffraction reveals anti-ferromagnetic ordering of the Cr(2+) moments in La2CrSe2O2 below TN = 12.7(3) K with an average ordered moment of 3.40(4) μB/Cr(2+) at 4 K, which was confirmed by muon spin rotation experiments.

  1. 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.

  2. Effect of rapid quenching on the magnetism and magnetocaloric effect of equiatomic rare earth intermetallic compounds RNi (R = Gd, Tb and Ho)

    Science.gov (United States)

    Rajivgandhi, R.; Arout Chelvane, J.; Quezado, S.; Malik, S. K.; Nirmala, R.

    2017-07-01

    Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P21/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (TC) respectively. While the melt-spun GdNi shows about 6 K increase in TC, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in TC by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆Sm, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials.

  3. Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts

    Science.gov (United States)

    Basith, M. A.; Islam, M. A.; Ahmmad, Bashir; Sarowar Hossain, M. D.; Mølhave, K.

    2017-07-01

    A simple route to prepare Gd0.7Sr0.3MnO3 nanoparticles by ultrasonication of their bulk powder materials is presented in this article. For comparison, Gd0.7Sr0.3MnO3 nanoparticles are also prepared by ball milling. The prepared samples are characterized by x-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive x-ray (EDX), x-ray photoelectron spectroscope (XPS), and superconducting quantum interference device (SQUID) magnetometer. XRD Rietveld analysis is carried out extensively for the determination of crystallographic parameters and the amount of crystalline and amorphous phases. FESEM images demonstrate the formation of nanoparticles with average particle size in the range of 50-100 nm for both ultrasonication and 4 h (h) of ball milling. The bulk materials and nanoparticles synthesized by both ultrasonication and 4 h ball milling exhibit a paramagnetic to spin-glass transition. However, nanoparticles synthesized by 8 h and 12 h ball milling do not reveal any phase transition, rather show an upturn of magnetization at low temperature. The degradation of the magnetic properties in ball milled nanoparticles may be associated with amorphization of the nanoparticles due to ball milling particularly for milling time exceeding 8 h. This investigation demonstrates the potential of ultrasonication as a simple route to prepare high crystalline rare-earth based manganite nanoparticles with improved control compared to the traditional ball milling technique.

  4. Large magnetocaloric effect in Ln{sub 0.5}Ca{sub 0.5}MnO{sub 3} (Ln=Gd, DY) compounds: Conseqence of magnetic precursor effect of rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kalipada, E-mail: kalipada.das@saha.ac.in; Paramanik, Tapas; Das, I.

    2015-01-15

    Magnetic, specific heat and magnetocaloric studies have been performed on rare earth calcium manganites; Ln{sub 0.5}Ca{sub 0.5}MnO{sub 3} (Ln=Gd, Dy). The observed isothermal magnetic entropy change is fairly large at low temperature in the manganites family, which is attributed to the magnetic precursor effect of rare-earth ions. For Gd{sub 0.5}Ca{sub 0.5}MnO{sub 3}, the isothermal magnetic entropy change (−ΔS) at 4 K, obtained for 7 T magnetic field, is as high as 22.8 J/kg K. On the other hand, −ΔS is 8.5 J/kg K for Dy{sub 0.5}Ca{sub 0.5}MnO{sub 3}. The large value of magnetic entropy change at the cryogenic temperature range for these compounds is interesting from application point of view. - Highlights: • No long range magnetic ordering of Gd{sub 0.5}Ca{sub 0.5}MnO{sub 3} and Dy{sub 0.5}Ca{sub 0.5}MnO{sub 3} has been observed in magnetization measurement down to T=2 K still these compounds show large magnetocaloric effect. • Specific heat of the compounds in absence of magnetic field increases at low temperature (down to 3 K). • Results are analyzed considering magnetic precursor effect of rare earth ions (Gd and Dy ions)

  5. China Not the Only Rare Earth Exporter

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Since China announced it was reducing exports of rare earth,there have been continuous voices in the international community demanding China expand exports or seek alternative resources.The United States has also complained to the WTO that China is hoarding the commodity.

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

    Science.gov (United States)

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

    2017-01-01

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

  7. Effect of Rare Earths on Composition and Activities of Rare Earth Elements Binding Glycoprotein in Tea

    Institute of Scientific and Technical Information of China (English)

    汪东风; 李俊; 赵贵文; 王常红; 魏正贵; 尹明

    2001-01-01

    The effects of spraying rare earths(RE) on composition and activities of tea polysaccharide were measured by inductively coupled plasma mass spectrometry (ICP-MS), gas chromatography(GC), amino acid analyzer and animal models. The results show that there are rare earth elements binding glycoprotein in tea (REE-TGP). The effects of RE on composition and content of saccharides in REE-TGP are not obvious. The contents of Hypro and Ser in REE-TGP are evidently enhanced in comparison with that in control (not treated with rare earth), but the content of Glu is smaller than that from control. The content of La in REE-TGP from the tea garden sprayed rare earth is 193% higher than that in control. REE-TGP declines content of blood sugar in mice and enhances immunization of rat, which are very evident when the animals are treated by REE-TGP from the tea garden sprayed RE.

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

    Science.gov (United States)

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

    2010-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-04-01

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

  10. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

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

  11. Rare Earth Additions in Continuously Cast Steel

    Science.gov (United States)

    Wilson, William G.; Heaslip, L. J.; Sommerville, I. D.

    1985-09-01

    Rare earth (lanthanide metals) addiiions to continuously cast steel are particularly advantageous because of their ability to refine as-cast structures, reduce segregation and increase hot ductility at temperatures just below that of solidification. The complete shape control of sulfides in steels containing Rare Earth Metals (REM), whether continuously cast or ingot cast, is primarily responsible for improvements in ductility related mechanical properties, weldability, fatigue resistance and resistance to hydrogen damage. Complete sulfide shape control can be obtained with REM additions at sulfur levels as high as.020%. The greatest improvements, however, are obtained with REM additions to low sulfur steels. However, to achieve full operational advantages afforded by REM, nozzle blockage problems must be circumvented. Water model studies indicate a possible solution.

  12. Rare earth optogalvanic spectroscopy: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Destro, Marcelo G.; Neri, Jose W.; Rodrigues, Nicolau A.S.; Silveira, Carlos A.B.; Riva, Rudimar [Instituto de Estudos Avancados (IEAv/EFO), Sao Jose dos Campos, SP (Brazil). Div. de Fotonica]. E-mail: destro@ieav.cta.br; Victor, Alessandro R. [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil)

    2008-07-01

    The IEAv has special interest in the studies of rare earth isotope applications in laser medium and integrated optics as well as aerospace research. We are starting to work with Ytterbium, Erbium, Dysprosium and Neodymium laser selective photoionization research. This paper describes the preliminary results of emission and optogalvanic spectroscopy obtained from a Neodymium hollow cathode lamps. Furthermore these results were used to setup our laser systems to work to leads a Nd isotopes selective laser photoionization. (author)

  13. Systematic variation of rare earths in monazite

    Science.gov (United States)

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

    1953-01-01

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

  14. Phase Behavior of Rare Earth Manganites

    Institute of Scientific and Technical Information of China (English)

    Naoki Kamegashira; Hiromi Nakano; Gang Chen; Jian Meng

    2004-01-01

    Among complex oxides containing rare earth and manganese BaLn2Mn2O7 (Ln=rare earth) with the layered perovskite type and Ln2(Mn, M)O7 with pyrochlore-related structure were studied since these compounds show many kinds of phases and unique phase transitions. In BaLn2Mn2O7 there appear many phases, depending on the synthetic conditions for each rare earth. The tetragonal phase of so-called Ruddlesden-Popper type is the fundamental structure and many kinds of deformed modification of this structure are obtained. For BaEu2Mn2O7 at least five phases have been identified from the results of X-ray diffraction analysis with the space group P42/mnm, Fmmm, Immm and A2/m in addition to the fundamental tetragonal I4/mmm phase. In the pyrochlore-related type compounds, Ln2Mn2-xMxO7 (M=Ta, Nb, W etc), there also appear several phases with different crystal structures. With regard to every rare earth, Ln2MnTaO7 phase is stable only for excess Ta and can be obtained under high oxygen partial pressure process. This group has trigonal structure with zirkelite type (P3121 space group). On the other hand Ln2Mn2/3Nb4/3O7 phase has monoclinic (C2/c space group) and zirconolite type structure. All of these structural models have the fundamental structure based on HTB (hexagonal tungsten bronze) layers formed by the arrangement of oxygen octahedra.

  15. Antiferromagnetic correlations in icosahedral R-Mg-Zn quasicrystals (R rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Charrier, B.; Schmitt, D. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Powder neutron-diffraction experiments performed on R-Mg-Zn quasicrystals have shown for the first time the existence of magnetic ordering of the rare earth in these systems at low temperature (T{sub c} {<=} 6.5 K depending on the rare earth). Both narrow and broad magnetic diffraction peaks have been observed showing the presence of two different scales of magnetic correlations. (author). 3 refs.

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

    Science.gov (United States)

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

    2009-03-01

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

  17. 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

  18. 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.)

  19. 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

  20. 3D print of polymer bonded rare-earth magnets, and 3D magnetic field scanning with an end-user 3D printer

    Science.gov (United States)

    Huber, C.; Abert, C.; Bruckner, F.; Groenefeld, M.; Muthsam, O.; Schuschnigg, S.; Sirak, K.; Thanhoffer, R.; Teliban, I.; Vogler, C.; Windl, R.; Suess, D.

    2016-10-01

    3D print is a recently developed technique, for single-unit production, and for structures that have been impossible to build previously. The current work presents a method to 3D print polymer bonded isotropic hard magnets with a low-cost, end-user 3D printer. Commercially available isotropic NdFeB powder inside a PA11 matrix is characterized, and prepared for the printing process. An example of a printed magnet with a complex shape that was designed to generate a specific stray field is presented, and compared with finite element simulation solving the macroscopic Maxwell equations. For magnetic characterization, and comparing 3D printed structures with injection molded parts, hysteresis measurements are performed. To measure the stray field outside the magnet, the printer is upgraded to a 3D magnetic flux density measurement system. To skip an elaborate adjusting of the sensor, a simulation is used to calibrate the angles, sensitivity, and the offset of the sensor. With this setup, a measurement resolution of 0.05 mm along the z-axes is achievable. The effectiveness of our calibration method is shown. With our setup, we are able to print polymer bonded magnetic systems with the freedom of having a specific complex shape with locally tailored magnetic properties. The 3D scanning setup is easy to mount, and with our calibration method we are able to get accurate measuring results of the stray field.

  1. Molecular catalysis of rare-earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Roesky, Peter W. (ed.) [Karlsruhe Institute of Technology (KIT) (Germany). Inst. of Inorganic Chemistry

    2010-07-01

    This volume reviews the recent developments in the use of molecular rare-earth metal compounds in catalysis. Most of the applications deal with homogenous catalysis but in some cases, heterogeneous systems are also mentioned. The rare-earth elements, which are the lanthanides and their close relatives - scandium and yttrium - have not been in the focus of molecular chemistry for a long time and therefore have also not been considered as homogenous catalysts. Although the first organometallic compounds of the lanthanides, which are tris(cyclopentadienyl) lanthanide complexes, were already prepared in the 1950s, it was only in the late 1970s and early 1980s when a number of research groups began to focus on this class of compounds. One reason for the development was the availability of single crystal X-ray diffraction techniques, which made it possible to characterize these compounds.Moreover, new laboratory techniques to handle highly air and moisture sensitive compounds were developed at the same time. Concomitant with the accessibility of this new class of compounds, the application in homogenous catalysis was investigated. One of the first applications in this field was the use of lanthanide metallocenes for the catalytic polymerization of ethylene in the early 1980s. In the last two or three decades, a huge number of inorganic and organometallic compounds of the rare-earth elements were synthesized and some of them were also used as catalysts. Although early work in homogenous catalysis basically focused only on the hydrogenation and polymerization of olefins, the scope for catalytic application today is much broader. Thus, a large number of catalytic {sigma}-bond metathesis reactions, e.g. hydroamination, have been reported in the recent years. This book contains four chapters in which part of the recent development of the use of molecular rare-earth metal compounds in catalysis is covered. To keep the book within the given page limit, not all aspects could be

  2. Rare-earth magnetism in cuprates with T' structure. [GdPrCuO; GdNdCuO; GdSmCuO; GdEuCuO

    Energy Technology Data Exchange (ETDEWEB)

    Czjzek, G. (Kernforschungszentrum Karlsruhe, INFP and ITP (Germany)); Roth, G. (Kernforschungszentrum Karlsruhe, INFP and ITP (Germany)); Kroener, T. (Kernforschungszentrum Karlsruhe, INFP and ITP (Germany)); Adelmann, P. (Kernforschungszentrum Karlsruhe, INFP and ITP (Germany))

    1994-02-01

    Cuprates of composition (Gd[sub 1-x]R[sub x])[sub 2]CuO[sub 4], R = Pr, Nd, Sm, Eu, have been studied by complementary experimental techniques. Only in compounds with Sm, exchange interactions between Sm and Cu moments are ineffective since the easy axis of the Sm moments is perpendicular to the Cu - O planes to which the Cu moments are confined. Here, we present new evidence that in the other cuprates with magnetic rare earths, R - Cu exchange interactions strongly influence the magnetic properties. (orig.)

  3. Rare Earth Elements in Global Aqueous Media

    Science.gov (United States)

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

    2012-12-01

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

  4. On the advantages of spring magnets compared to pure FePt: Strategy for rare-earth free permanent magnets following a bottom-up approach

    Science.gov (United States)

    Pousthomis, M.; Garnero, C.; Marcelot, C. G.; Blon, T.; Cayez, S.; Cassignol, C.; Du, V. A.; Krispin, M.; Arenal, R.; Soulantica, K.; Viau, G.; Lacroix, L.-M.

    2017-02-01

    Nanostructured magnets benefiting from efficient exchange-coupling between hard and soft grains represent an appealing approach for integrated miniaturized magnetic power sources. Using a bottom-up approach, nanostructured materials were prepared from binary assemblies of bcc FeCo and fcc FePt nanoparticles and compared with pure L10-FePt materials. The use of a bifunctional mercapto benzoic acid yields homogeneous assemblies of the two types of particles while reducing the organic matter amount. The 650 °C thermal annealing, mandatory to allow the L10-FePt phase transition, led to an important interdiffusion and thus decreased drastically the amount of soft phase present in the final composites. The analysis of recoil curves however evidenced the presence of an efficient interphase exchange coupling, which allows obtaining better magnetic performances than pure L10 FePt materials, energy product above 100 kJ m-3 being estimated for a Pt content of only 33%. These results clearly evidenced the interest of chemically grown nanoparticles for the preparation of performant spring-magnets, opening promising perspective for integrated subcentimetric magnets with optimized properties.

  5. 3D Print of Polymer Bonded Rare-Earth Magnets, and 3D Magnetic Field Scanning With an End-User 3D Printer

    CERN Document Server

    Huber, C; Bruckner, F; Groenefeld, M; Muthsam, O; Schuschnigg, S; Sirak, K; Thanhoffer, R; Teliban, I; Windl, R; Suess, and D

    2016-01-01

    3D print is a recently developed technique, for single-unit production, and for structures that have been impossible to build previously. The current work presents a method to 3D print polymer bonded isotropic hard magnets with a low-cost, end-user 3D printer. Commercially available material is characterized, and prepared for the printing process. An example of a printed magnet with a complex shape that was designed to generate a specific stray field is presented, and compared with FEM simulation results. For magnetic characterization, and comparing 3D printed structures with injection molded parts, hysteresis measurements are performed. To measure the stray field around the magnet, the printer is upgraded to a 3D magnetic flux density measurement system. To skip an elaborate adjusting of the sensor, a simulation is used to calibrate the angles, sensitivity, and the offset of the sensor. With this setup a measurement resolution of 0.05\\,mm along the z-axes is achievable. The effectiveness of our novel calibra...

  6. An Integrated Rare Earth Elements Supply Chain Strategy

    Science.gov (United States)

    2011-02-24

    FL: CRC Press, 2005) 1, 61, 59. 7 Gupta and Krishnamurthy, Extractive Metallurgy of Rare Earths, 21, 22, 32; Cindy A. Hurst, ―China‘s Ace in the...Supply Chain, Briefing for Congressional Committees, 27. 17 Ibid, 24. 18 Gupta and Krishnamurthy, Extractive Metallurgy of Rare Earths, 57. 19 Ibid...Oct 12, 2010): 3. 38 Gupta and Krishnamurthy, Extractive Metallurgy of Rare Earths, 94. 39 U.S. Government Accountability Office, Rare Earth

  7. Reduction property of rare earth oxide doped molybdenum oxide

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rare earth oxide doped molybdenum powders were prepared by the reduction of rare earth nitrites doped MoO3. The effect of rare earth oxide on the reduction behavior of molybdenum oxide had been studied by means of Temperature Programmed Reduction (TPR), thermal analysis, X-ray diffraction. Doping rare earth oxide in the powder could lower the reduction temperature of molybdenum oxide and decrease the particle size of molybdenum. The mechanism for the effects had been discussed in this paper.

  8. 2007 China Rare Earths Import & Export Analysis and Suggestions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Ⅰ. Chinese rare earth import & export status in 2007 China further strengthened regulations on import & export of rare earth products in 2007. Firstly, NDRC changed the guidance for rare earth production from guiding plan into mandatory plan at the year beginning.

  9. CISRI Competes for Light Rare Earth in North China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>In the light rare earth market of north China,REHT,the largest rare earth enterprise in the world,has to face a bitter rival in competition.As 3 SOEs(CHINALCO,Minmetals and CNMC)are vying for the medium and heavy rare earth market of South China,a smaller SOE,i.e.,China Iron & Steel Research

  10. China is Planning to Raise rare Earth Resource Tax Again

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>In the face of the current situation of the lost WTO dispute on rare earth,and cancellation of export tariff for partial rare earth products,efforts of regulation and integration on rare earth by the state government will again be tightened.Reporters of the Economic Information Daily recently learned from authoritative sources that relevant ministries are

  11. 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)

  12. 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.

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

    Science.gov (United States)

    Thompson, Corey Mitchell

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

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

    Science.gov (United States)

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

    2011-01-01

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

  15. Magnetocaloric effect in rare-earth intermetallics: Recent trends

    Indian Academy of Sciences (India)

    R Nirmala; A V Morozkin; S K Malik

    2015-06-01

    Magnetocaloric effect (MCE) is the change in isothermal magnetic entropy (m)and adiabatic temperature (ad) that accompany magnetic transitions in materials during the application or the removal of magnetic field under adiabatic conditions. The physics of MCE gets enriched by correlated spin-lattice degrees of freedom. This phenomenon has been actively investigated over the past few decades as it holds a promise for an alternate method of refrigeration/heat pumping. This has already resulted in several reviews on this topic. This paper focusses on some recent trends in this field and prospects of using rare-earth-based materials as active magnetic refrigerants over a broad temperature range that includes gas liquefaction and near-room temperature refrigeration/heating.

  16. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

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

  17. Structures and magnetic properties of rare earth double perovskites containing antimony or bismuth Ba{sub 2}LnMO{sub 6} (Ln=rare earths; M=Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Shumpei, E-mail: m-nis-s-o@ec.hokudai.ac.jp; Hinatsu, Yukio

    2015-07-15

    A series of double perovskite-type oxides Ba{sub 2}LnMO{sub 6} (Ln=lanthanides; M=Sb, Bi) were synthesized and their structures were studied. The Ln and M are structurally ordered in the rock-salt type at the B-site of the perovskite ABO{sub 3}. For Ba{sub 2}PrBiO{sub 6} and Ba{sub 2}TbBiO{sub 6}, it has been found that the disordering between Ln ion and Bi ion occurs at the B-site of the double perovskite and both the Pr (Tb) and Bi exist in two oxidation state in the same compound from the analysis of the X-ray diffraction and magnetic susceptibility data. Magnetic susceptibility measurements show that all these compounds are paramagnetic and have no magnetic ordering down to 1.8 K. - Graphical abstract: Tolerance factor for Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) plotted against the ionic radius of Ln{sup 3+}. We have found that there is a clear relation between crystal structures and tolerance factors. - Highlights: • The Ln and M ions are structurally ordered in the rock-salt type at the B-site. • The disordering between Pr (Tb) ion and Bi ion occurs at the B-site. • Ba{sub 2}LnMO{sub 6} (M=Sb, Bi) have no magnetic ordering down to 1.8 K.

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

    Energy Technology Data Exchange (ETDEWEB)

    Imashuku, Susumu, E-mail: imashuku.susumu.2m@kyoto-u.ac.jp; Fuyuno, Naoto; Hanasaki, Kohei; Kawai, Jun [Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501 (Japan)

    2013-12-15

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

  19. Measuring Earth's Magnetic Field Simply.

    Science.gov (United States)

    Stewart, Gay B.

    2000-01-01

    Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)

  20. Magnetic field of the Earth

    Science.gov (United States)

    Popov, Aleksey

    2013-04-01

    The magnetic field of the Earth has global meaning for a life on the Earth. The world geophysical science explains: - occurrence of a magnetic field of the Earth it is transformation of kinetic energy of movements of the fused iron in the liquid core of Earth - into the magnetic energy; - the warming up of a kernel of the Earth occurs due to radioactive disintegration of elements, with excretion of thermal energy. The world science does not define the reasons: - drift of a magnetic dipole on 0,2 a year to the West; - drift of lithospheric slabs and continents. The author offers: an alternative variant existing in a world science the theories "Geodynamo" - it is the theory « the Magnetic field of the Earth », created on the basis of physical laws. Education of a magnetic field of the Earth occurs at moving the electric charge located in a liquid kernel, at rotation of the Earth. At calculation of a magnetic field is used law the Bio Savara for a ring electric current: dB = . Magnetic induction in a kernel of the Earth: B = 2,58 Gs. According to the law of electromagnetic induction the Faradey, rotation of a iron kernel of the Earth in magnetic field causes occurrence of an electric field Emf which moves electrons from the center of a kernel towards the mantle. So of arise the radial electric currents. The magnetic field amplifies the iron of mantle and a kernel of the Earth. As a result of action of a radial electric field the electrons will flow from the center of a kernel in a layer of an electric charge. The central part of a kernel represents the field with a positive electric charge, which creates inverse magnetic field Binv and Emfinv When ?mfinv = ?mf ; ?inv = B, there will be an inversion a magnetic field of the Earth. It is a fact: drift of a magnetic dipole of the Earth in the western direction approximately 0,2 longitude, into a year. Radial electric currents a actions with the basic magnetic field of a Earth - it turn a kernel. It coincides with laws

  1. Crystal structure and magnetism of the MnxGa (1.15 ≤x ≤ 2.0 rare-earth-free permanent magnet system

    Directory of Open Access Journals (Sweden)

    Rasa Rejali

    2016-05-01

    Full Text Available Room temperature neutron powder diffraction has been used to investigate the chemical structure and magnetic ordering of a series of tetragonal (I4/mmm #139 MnxGa (1.15 ≤ x ≤ 2.0 alloys. Initially (x 1.5 Mn also appears on the 2a site. The manganese atoms on the 4d site carry an almost constant moment of 2.16(6 μB/Mn. The loss of magnetisation seen with increasing Mn content is shown to be the result of large (∼3 μB/Mn, antiparallel Mn moments on the 2b, and later 2a sites, and not to a reduction of the Mn moment on the 4d sites.

  2. Charge-order driven multiferroic and magneto-dielectric properties of rare earth manganates

    Indian Academy of Sciences (India)

    Claudy Rayan Serrao; Jyoti Ranjan Sahu; Anirban Ghosh

    2010-04-01

    Charge-order driven magnetic ferroelectricity is shown to occur in several rare earth manganates of the general formula, Ln1–AMnO3 (Ln = rare earth, A = alkaline earth). Charge-ordered manganates exhibit dielectric constant anomalies around the charge-ordering or the antiferromagnetic transition temperature. Magnetic fields have a marked effect on the dielectric properties of these compounds, indicating the presence of coupling between the magnetic and electrical order parameters. Magneto-dielectric properties are retained in small particles of the manganates. The observation of magneto-ferroelectricity in these manganates is in accordance with theoretical predictions.

  3. Transformation from an easy-plane to an easy-axis antiferromagnetic structure in the mixed rare-earth ferroborates Pr x Y1-x Fe3(BO3)4: magnetic properties and crystal field calculations.

    Science.gov (United States)

    Pankrats, A I; Demidov, A A; Ritter, C; Velikanov, D A; Semenov, S V; Tugarinov, V I; Temerov, V L; Gudim, I A

    2016-10-05

    The magnetic structure of the mixed rare-earth system Pr x Y1-x Fe3(BO3)4 (x  =  0.75, 0.67, 0.55, 0.45, 0.25) was studied via magnetic and resonance measurements. These data evidence the successive spin reorientation from the easy-axis antiferromagnetic structure formed in PrFe3(BO3)4 to the easy-plane one of YFe3(BO3)4 associated with the weakening of the magnetic anisotropy of the Pr subsystem due to its diamagnetic dilution by nonmagnetic Y. This reorientation occurs through the formation of an inclined magnetic structure, as was confirmed by our previous neutron research in the range of x  =  0.67 ÷ 0.45. In the compounds with x  =  0.75 and 0.67 whose magnetic structure is close to the easy-axis one, a two-step spin reorientation takes place in the magnetic field H||c. Such a peculiarity is explained by the formation of an interjacent inclined magnetic structure with magnetic moments of Fe ions located closer to the basal plane than in the initial state, with these intermediate states remaining stable in some ranges of the magnetic field. An approach based on a crystal field model for the Pr(3+) ion and the molecular-field approximation is used to describe the magnetic characteristics of the system Pr x Y1-x Fe3(BO3)4. With the parameters of the d-d and f-d exchange interactions, of the magnetic anisotropy of the iron subsystem and of the crystal field parameters of praseodymium thus determined, it is possible to achieve a good agreement between the experimental and calculated temperature and field dependences of the magnetization curves (up to 90 kOe) and magnetic susceptibilities (2-300 K).

  4. Hydrophobicity of rare-earth oxide ceramics

    Science.gov (United States)

    Azimi, Gisele; Dhiman, Rajeev; Kwon, Hyuk-Min; Paxson, Adam T.; Varanasi, Kripa K.

    2013-04-01

    Hydrophobic materials that are robust to harsh environments are needed in a broad range of applications. Although durable materials such as metals and ceramics, which are generally hydrophilic, can be rendered hydrophobic by polymeric modifiers, these deteriorate in harsh environments. Here we show that a class of ceramics comprising the entire lanthanide oxide series, ranging from ceria to lutecia, is intrinsically hydrophobic. We attribute their hydrophobicity to their unique electronic structure, which inhibits hydrogen bonding with interfacial water molecules. We also show with surface-energy measurements that polar interactions are minimized at these surfaces and with Fourier transform infrared/grazing-angle attenuated total reflection that interfacial water molecules are oriented in the hydrophobic hydration structure. Moreover, we demonstrate that these ceramic materials promote dropwise condensation, repel impinging water droplets, and sustain hydrophobicity even after exposure to harsh environments. Rare-earth oxide ceramics should find widespread applicability as robust hydrophobic surfaces.

  5. Parity Violation Experiments with Rare Earth Atoms

    Science.gov (United States)

    Budker, Dmitry

    1997-10-01

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

  6. On the structural and magnetic properties of R{sub 2}Fe{sub 17-x}(A,T){sub x} (R=rare earth; A=Al, Si, Ga; T=transition metal) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rama Rao, K.V.S. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Ehrenberg, H.; Fuess, H. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Markandeyulu, G.; Murthy, V.S. [Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Varadaraju, U.V.; Venkatesan, M. [Indian Inst. of Tech., Madras (India). Materials Science Research Centre; Suresh, K.G. [Indian Inst. of Tech., Bombay (India). Dept. of Physics; Schmidt, P.C. [Technische Univ. Darmstadt (Germany). Inst. fuer Physikalische Chemie

    2002-02-16

    R{sub 2}Fe{sub 17} (R = rare earth) intermetallic compounds constitute one of the most important classes of materials identified as high-energy permanent magnet materials. They crystallize either in the rhombohedral Th{sub 2}Zn{sub 17} structure (for light R) or in the hexagonal Th{sub 2}Ni{sub 17} structure (for heavy R). In this article, we discuss the variations in the lattice parameters (unit cell volume), site occupancies and Curie temperature when non-transition and transition metals are substituted for Fe in R{sub 2}Fe{sub 17} compounds. (orig.)

  7. Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts

    DEFF Research Database (Denmark)

    Basith, M. A.; Islam, M. A.; Ahmmad, Bashir

    2017-01-01

    A simple route to prepare Gd0.7Sr0.3MnO3 nanoparticles by ultrasonication of their bulk powder materials is presented in this article. For comparison, Gd0.7Sr0.3MnO3 nanoparticles are also prepared by ball milling. The prepared samples are characterized by X-ray diffraction (XRD), field emission...... of crystalline and amorphous phases. FESEM images demonstrate the formation of nanoparticles with average particle size in the range of 50–100 nm for both ultrasonication and 4 h (h) of ball milling. The bulk materials and nanoparticles synthesized by both ultrasonication and 4 h ball milling exhibit...... of the nanoparticles due to ball milling particularly for milling time exceeding 8 h. This investigation demonstrates the potential of ultrasonication as a simple route to prepare high crystalline rare-earth based manganite nanoparticles with improved control compared to the traditional ball milling technique....

  8. 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.

  9. Opinions on hot discussions in connection with rare earths recently

    Institute of Scientific and Technical Information of China (English)

    SONG Hongfang; HONG Mei

    2011-01-01

    @@ Rare earth industry, with production value less than 30 trillion yuan, has become the hot topic both inside China and in the rest of the world since 2009. Even in stock market, rare earth was one of the most active sectors. Media in various countries, specialists in different fields and many political figures worldwide as well as some netizens showed extraordinary concerns on rare earths. Many heated arguments were made on the hot and even some sensitive topics about rare earth industry. Rare earth issues seem to be beyond the industrial production today, but the subject focused on economy, politics and strategic importance. The word "rare earth" was a yearly hot point or a key word in 2010.

  10. Study on Mechanism of Rare Earth PVC Stabilizer

    Institute of Scientific and Technical Information of China (English)

    彭振博; 胡斌; 苏庆德; 曲锦忠

    2003-01-01

    Rare earth compounds can be used as PVC thermal stabilizers. According to the infrared spectra of the mixture of PVC and some stearates, the mechanism of stabilization of different stearates was studied. The specialty of rare earth stabilizers was found. They can change the conformation of PVC and restrain the elimination of HCl. From this aspect, the unique synergetic effect with other stabilizers of rare earth compounds can be explained.

  11. GRNM Likely to Spearhead Reshuffle of Guangdong Rare Earth Industry

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>"Guangdong intends to build a rare earth platform named Guangdong Rare Earth Group, and the plan has been probably approved recently." An insider of local government said, "although there is no final conclusion, but the Guangdong’s intention to build a general platform of rare earth is clear." Since Guangdong Rising Nonferrous Metals Group Co., Ltd. (GRNM) is the only local state-owned enterprise leading

  12. China Limits the Mining Quantity of Tungsten and Rare Earth

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    <正>Based on a notice issued by the Ministry of Land Resources, China’s tungsten mining quantity in 2006 will be controlled to 59,060 tons in concentrates form, which include 4,250 tons of recycled tungsten. And the rare earth mining quantity in 2006 will also be controlled to 86,620 tons (REO) including 8,320 tons of heavy rare earth and 78,200 tons of light rare earth.

  13. Study on Copolymerization of Rare Earth-Carboxylic Acid Complex

    Institute of Scientific and Technical Information of China (English)

    Qiu Guanmin(邱关明); Zhang Ming(张明); Yan Chang hao(严长浩); Zhou Lanxiang(周兰香); Dai Shaojun(戴少俊); Okamo to Hiroshi

    2003-01-01

    Complex of rare earth with carboxylic acid was prepared by precipita tion and direct method. It was copolymerized with such monomers as acrylic acid and other ones to synthesize ionomer of rare earth and organic polymer with different rare earth contents. Its glass-transition temperature and heat stability were analyzed by TG and DTA. Infra-red detector was used to show its structure. The effect of rare earth complex prepared by different methods on copolymerization and properties of copolymers was also discussed.

  14. Storing Solar Energy Performance on Rare Earth Windowpane

    Institute of Scientific and Technical Information of China (English)

    Li Baojun; Zhou Yao; Fu Li; Yang Tao; Li Tiansi; Li Ying

    2004-01-01

    The windowpane as the enclosure and decorative component of buildings is main part of energy consumption and the heat loss through window is almost 4% of the heating consumption in buildings. Using rare earth element,the glass can possess the performance of absorbing sunlight, storing heat, increasing the temperate of itself, and decreasing the inner heat load so as to play the double functions of saving energy and environmental protection. The experiment method of the rare earth windowpane, and analyses sunlight absorbing process of the rare earth element on photoelectric principle, and gives the changing curve with environment temperate -time of the rare earth windowpane surface were introduced.

  15. 稀土-过渡金属薄膜磁各向异性的理论研究%Theoretic studies on the magnetic anisotropy of rare-earth transition-metal thin films

    Institute of Scientific and Technical Information of China (English)

    何一鸣; 钱显毅; 黄致新

    2011-01-01

    The magnetic anisotropy of rare-earth transition-metal thin films is investigated in this paper. Based on the reference review and the analysis of thin film forming process by sputtering, the single ion model has been put foreword. With concrete computation, we found that when the composition of the film is R31Co69 and the rare-earth element is Tb, the magnetic anisotropy value can be as high as 3. 1×106 erg/cm3. And the Coulomb interactions between the non-S state rare-earth ion in non-spherical electric charge distribution with the deformed local crystalline field accounts for the major source of high perpendicular anisotropy of TbCo amorphous films.%对稀土-过渡金属薄膜的磁各向异性进行了理论分析研究.通过分析其它模型以及薄膜成膜过程的特点,建立了单离子模型,并进行了理论分析和计算.结果发现:组分为R31Co69薄膜中稀土元素R为Tb时的Ku值最大,接近3.1×106 erg/cm3.对于TbCo非晶垂直磁化膜而言,具有非球对称电荷分布的非S态离子Tb与局部电场的相互作用构成了其垂直磁各向异性的主要部分.

  16. Effect of rare earth additions on magnetic properties of Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} (RE = Y, Gd, Tb and Dy) amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chrobak, A., E-mail: artur.chrobak@us.edu.pl [Institute of Physics, Silesian University, 4 Uniwersytecka, 40-007 Katowice (Poland); Nosenko, V. [G.V. Kurdyumov Institute for Physics of Metals, NAS of Ukraine, Vernadsky ave. 36, 03142 Kyiv (Ukraine); Haneczok, G. [University of Silesia, Institute of Materials Science, 12 Bankowa, 40-007 Katowice (Poland); Boichyshyn, L.; Kotur, B. [Ivan Franko National University of Lviv, Kyryla and Mefodia St. 6, 79005 Lviv (Ukraine); Bajorek, A. [Institute of Physics, Silesian University, 4 Uniwersytecka, 40-007 Katowice (Poland); Zivotsky, O.; Hendrych, A. [Technical University of Ostrava, Institute of Physics, 17. listopadu 15, 708 33 Ostrava-Poruba (Czech Republic)

    2011-10-17

    Highlights: {yields} We studied magnetic properties of Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} (RE=Y,Gd,Tb,Dy) amorphous alloys. {yields} In a comparison with Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} alloy the rare earth editions cause an increase of the Curie temperature and a decrease of magnetic moment per magnetic atom. {yields} Doping of Tb and Dy lead to a strong decrease of magnetic permeability and a formation of low dimensional finger-print magnetic domains. - Abstract: In the present paper the influence of RE alloying additions (Y, Gd, Tb and Dy) on magnetic properties (Curie temperatures, low temperature magnetization, zero field cooling-field cooling curves, domain structure, room temperature magnetostriction and magnetic permeability) of amorphous alloys of type Fe{sub 82}Nb{sub 2}B{sub 14}RE{sub 2} are carefully examined. It was shown that substituting of yttrium atoms by magnetic elements, i.e. Gd, Tb and Dy leads to (i) an increase of the Curie temperature of amorphous phase from 416 K (for Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2}) to 450 K (for Fe{sub 82}Nb{sub 2}B{sub 14}Gd{sub 2}) and (ii) a decrease of magnetization in saturation (magnetic field 7 T) which can be explained by antiferromagnetic Fe-RE coupling resulting in a decrease of magnetic moment calculated per magnetic atom from 2.00 {mu}{sub B} for the Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} alloy (Fe in amorphous phase) to 1.51 {mu}{sub B} for the Fe{sub 82}Nb{sub 2}B{sub 14}Tb{sub 2} alloy. It was concluded that Tb and Dy alloying additions introduce a local magnetic anisotropy responsible for significant decrease of initial magnetic permeability (about 5 times in relation to Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} or Fe{sub 82}Nb{sub 2}B{sub 14}Gd{sub 2} alloy), increase of magnetic irreversibility effect measured at 2 K (about 10 times in relation to the same alloys) and appearing of the finger-print magnetic domain regions (not observed for the Fe{sub 82}Nb{sub 2}B{sub 14}Y{sub 2} and Fe{sub 82}Nb

  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. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    BHALLA VYOMA; SINGH DEVRAJ; JAIN S K; KUMAR RAJ

    2016-06-01

    The present paper deals with the theoretical calculation of mechanical and thermophysical properties of rare-earth monoarsenides, XAs (X: Np, Pu, Th and U) using elastic constants as the input parameters. These second- and third-order elastic constants (SOECs and TOECs) are determinedin the temperature range 100–500K using Coulomb and Born–Mayer potential upto second nearest neighbours. In order to provide the link between mechanical and dynamical behaviour of crystals, parameters such as Young’s modulus, bulk modulus, Poisson’s ratio etc. are also calculated.In addition, the Cauchy relationship is obeyed by the chosen monoarsenides and are fairly anisotropic, which results in the measurement of longitudinal and shear wave velocities along $\\langle100 \\rangle$, $\\langle110\\rangle$ and $\\langle 111\\rangle$ directions. The toughness/fracture $(G/BT)$ ratio is greater than 0.60, which implies that XAs compounds are brittle at room temperature. Further, the Debye temperature is computed using Debye average velocity as the input parameter. It helps in the characterization of lattice vibrations of a solid. In this work, ultrasonic attenuation due to phonon–phonon interaction$\\alpha/f^2_{\\rm p−p}$ and thermoelastic loss $\\alpha/f ^{2}$th are computed for XAs from 100 to 500K using Mason’s theory. It further helps in evaluating the microstructural properties of the chosen materials. The obtained results indicate that XAs is mechanically stable and are compared with data availablein the literature.

  19. Electrical and magnetic properties of quaternary rare earth thiophosphate: K{sub 4}Sm{sub 2}[PS{sub 4}]{sub 2}[P{sub 2}S{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Manriquez, Victor; Galdamez, Antonio; Cerda-Monje, Andrea [Universidad de Chile, Santiago (Chile). Facultad de Ciencias. Dept. de Quimica], e-mail: vmanriqu@uchile.cl; Pena, Octavio [Universite de Rennes 1, Rennes cedex (France). Sciences Chimiques de Rennes; Avila, Ricardo E. [Comision Chilena de Energia Nuclear, Santiago (Chile). Dept. de Materiales Nucleares

    2009-07-01

    The quaternary alkali metal, rare earth thiophosphate phase K{sub 4}Sm{sub 2}[PS{sub 4}]{sub 2}[P{sub 2}S{sub 6}] was synthesized by ceramic method and characterized by powder X-ray diffraction (XRD), SEM-EDX scanning electron microscope-microprobe analyses, electrochemical impedance and magnetic measurements. The crystal structure consists of layers of {sup 2}{infinity}Sm{sub 2}[PS{sub 4}]{sub 2}[P{sub 2}S{sub 6}]{sup 4-} separated by K{sup +} cations. The electrical conductivity measurements indicate that the compound is a semiconductor with a resistivity of 1.0 x10{sup 11} {omega} cm. The magnetic moment, evaluated from X{sup -1} versus T at low temperature is 0.57 {mu}{sub B}. (author)

  20. Terras raras: aplicações industriais e biológicas Rare earths: industrial and biological applications

    Directory of Open Access Journals (Sweden)

    Tereza S. Martins

    2005-02-01

    Full Text Available The history of the rare earths is rich in innovation and these elements have been the object of study of a number of scientists. Rare earths are used practically in almost all aspects of life and these applications are due to their outstanding properties, mainly spectroscopic and magnetic. In industry, the applications of rare earths are many, such as in catalysis, phosphors, magnetism, glass and lasers. In biological systems, rare earths are used, for example, as luminescent probes in the investigation of binding sites in proteins, labels in immunoassays and in noninvasive tests.

  1. Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

    Science.gov (United States)

    Escudero, Alberto; Becerro, Ana I.; Carrillo-Carrión, Carolina; Núñez, Nuria O.; Zyuzin, Mikhail V.; Laguna, Mariano; González-Mancebo, Daniel; Ocaña, Manuel; Parak, Wolfgang J.

    2017-06-01

    Rare earth based nanostructures constitute a type of functional materials widely used and studied in the recent literature. The purpose of this review is to provide a general and comprehensive overview of the current state of the art, with special focus on the commonly employed synthesis methods and functionalization strategies of rare earth based nanoparticles and on their different bioimaging and biosensing applications. The luminescent (including downconversion, upconversion and permanent luminescence) and magnetic properties of rare earth based nanoparticles, as well as their ability to absorb X-rays, will also be explained and connected with their luminescent, magnetic resonance and X-ray computed tomography bioimaging applications, respectively. This review is not only restricted to nanoparticles, and recent advances reported for in other nanostructures containing rare earths, such as metal organic frameworks and lanthanide complexes conjugated with biological structures, will also be commented on.

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

    Indian Academy of Sciences (India)

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

    2012-03-01

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

  3. Synthesis and Characterization of Rare Earth Solid Complexes with Sodium 5-Aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiuying; Li Shujing; Lei Xuefeng; Ma Junxian

    2005-01-01

    Ten new rare earth solid complexes were synthesized by the reaction of sodium 5-aminosalicyliate with rare earth chloride. The structure character, physical and chemical properties of these complexes were studied by IR, UV, 1H NMR spectra, TG-DTA, fluorescence, elemental analyses, molar conductance and magnetic susceptibility. The ten rare earth complexes exist in dimeric form probably and the coordination number is seven. The antibacterial activity of the ligand and six complexes was also tested against Staphylococcus aureus, Escherichia coli and Bacillus subtilis, and the effect of Yb complex at 20 mg·ml-1 against Staphylococcus aureus is most significant.

  4. Fast synthesis of rare-earth (Pr{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Gd{sup 3+}) doped bismuth ferrite powders with enhanced magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Iorgu, A.I. [Department of Chemical Thermodynamics, “Ilie Murgulescu” Institute of Physical Chemistry, 060021 Bucharest (Romania); Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania); Maxim, F., E-mail: fmaxim@icf.ro [Department of Chemical Thermodynamics, “Ilie Murgulescu” Institute of Physical Chemistry, 060021 Bucharest (Romania); Matei, C. [Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania); Ferreira, Liliana Pires [Centro de Física da Matéria Condensada, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Department of Physics, University of Coimbra, 3004-516 Coimbra (Portugal); Ferreira, P. [Department of Materials and Ceramics Engineering, CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Cruz, M.M. [Centro de Física da Matéria Condensada, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Berger, D., E-mail: danaberger01@yahoo.com [Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, University “Politehnica” of Bucharest, 011061 Bucharest (Romania)

    2015-04-25

    Highlights: • Synthesis of rare earth doped bismuth ferrite powders by combustion method. • SEM and TEM were used to investigate the morphology and size of particles. • Effect of Bi substitution with Pr, Sm, Eu and Gd on magnetic properties of powders. - Abstract: Rare-earth (Pr{sup 3+}, Sm{sup 3+}, Eu{sup 3+} and Gd{sup 3+}) doped bismuth ferrite powders were synthesized for the first time by solution combustion method, which is a fast soft chemistry route for obtaining oxide powders. The materials were investigated by X-ray diffraction, Raman spectroscopy, as well as scanning and transmission electron microscopy. A distortion from rhombohedral R3c symmetry, specific to pure bismuth ferrite, to orthorhombic symmetry was observed for all doped samples. The SEM analysis of pure and doped bismuth ferrite powders showed the formation of sintered grains, with faceted cuboids-shaped particles with different size and lower average dimension in the case of doped samples. Magnetic properties were analyzed using SQUID magnetometry, M–H hysteresis loops being measured at 10 K and 300 K. All studied pure and doped bismuth ferrite samples presented high susceptibility values for high magnetic fields indicating strong antiferromagnetic interactions, whereas the behavior at low magnetic field demonstrates the existence of ferromagnetic coupling. Compared to BiFeO{sub 3}, Bi{sub 0.9}RE{sub 0.1}FeO{sub 3} (RE = Pr, Sm, Eu and Gd) powders exhibit higher susceptibility, remanence and coercivity values, Bi{sub 0.9}Eu{sub 0.1}FeO{sub 3} sample displaying the highest remanence and coercivity at room temperature.

  5. Research trends in rare earths: A preliminary analysis

    Institute of Scientific and Technical Information of China (English)

    Gin-ya

    2010-01-01

    The research trend in rare earths has been studied using the Chemical Abstracts (CA) data.The number of papers published from China has been increasing very rapidly since 2001 and today China is the top country in terms of paper contribution on rare earths.This article presents a comparative study of R & D trends among China,Japan and USA.

  6. Shanghai Rare Earth Industry Scale is Expected to Double

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>A new organization in the rare earth industry circle in Shanghai initiated and set up by 14 enterprises and public institutions called "Shanghai Rare Earth Association", formally declared its establishment recently. This marked China’s only specialized and non-profit

  7. Imports εt Exports Review of Chinese Rare Earths

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ China developed herself from being predominant at RE resources into a country with the largest production, the highest export volume and the largest application of rare earth products in the world. Today, China plays a leading role in the global rare earth market.

  8. Review and outlook of 2008 China rare earth market

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lihua

    2009-01-01

    @@ I.Environment and trend of RE market 1.Operation environment in 2008 Chinese government further strengthened its macro-control on rare earth industry in 2008.Mandatory planning policy was implemented in the production of rare earth minerals and smelted products.

  9. 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

  10. Rare earth elements in Hamersley BIF minerals

    Science.gov (United States)

    Alibert, Chantal

    2016-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  12. Effect of rare earth substitution in cobalt ferrite bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Bulai, G., E-mail: georgiana.bulai@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Diamandescu, L. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Dumitru, I.; Gurlui, S. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania); Feder, M. [National Institute of Material Physics, P.O. Box MG-7, 07125 Bucharest (Romania); Caltun, O.F. [Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bd. Carol I, nr. 11, 700506 Iasi (Romania)

    2015-09-15

    The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm{sup −3} decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe{sub 2}O{sub 4} sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples.

  13. Prospective analysis of the flows of certain rare earths in Europe at the 2020 horizon.

    Science.gov (United States)

    Rollat, Alain; Guyonnet, Dominique; Planchon, Mariane; Tuduri, Johann

    2016-03-01

    This paper proposes a forecast of certain rare earth flows in Europe at the 2020 horizon, based on an analysis of trends influencing various actors of the rare earth industry along the value chain. While 2020 is indicated as the forecast horizon, the analysis should be considered as more representative of the next decade. The rare earths considered here are used in applications that are important for a low-carbon energy transition and/or have a significant recycling potential: NdFeB magnets (Pr, Nd, Dy), NiMH batteries (Pr, Nd) and fluorescent lamp phosphors (Eu, Tb, Y). An analysis of major trends affecting the rare earth industry in Europe along the value chain (including extraction, separation, fabrication, manufacture, use and recycling), helps to build a scenario for a material flow analysis of these rare earths in Europe. The scenario assumes in particular that during the next decade, there exists a rare earth mine in production in Europe (with Norra Kärr in Sweden as a most likely candidate) and also that recycling is in line with targets proposed in recent European legislation. Results are presented in the form of Sankey diagrams which help visualize the various flows for the three applications. For example, calculations forecast flows from extraction to separation of Pr, Nd and Dy for magnet applications in Europe, on the order of 310 tons, 980 tons and 80 tons rare earth metal resp., while recycled flows are 35 tons, 110 tons and 30 tons resp. Calculations illustrate how the relative contribution of recycling to supply strongly depends on the situation with respect to demand. Considering the balance between supply and demand, it is not anticipated any significant shortage of rare earth supply in Europe at the 2020 horizon, barring any new geopolitical crisis involving China. For some heavy rare earths, supply will in fact largely outweigh demand, as for example Europium due to the phasing out of fluorescent lights by LEDs.

  14. Magnetic structures of new uranium or rare earth based ternary stannides T{sub 2}M{sub 2}Sn (T = RE, U and M = Ni, Pd); Structures magnetiques de nouveaux stannures ternaires a base d'uranium ou de terres rares T{sub 2}M{sub 2}Sn (T=U, RE et M=Ni, Pd)

    Energy Technology Data Exchange (ETDEWEB)

    Laffargue, D

    1997-07-15

    Magnetic structures of new ternary stannides T{sub 2}M{sub 2}Sn (T = U, RE and M Ni, Pd) have been determined by powder neutron diffraction. A precise study of U{sub 2}M{sub 2}Sn (M = Ni, Pd) compounds showed several relations between structural and magnetic properties. The hybridization effects between 5f(U) and 3d(Ni) states is responsible for the weak magnetic moment observed on the uranium atoms in U{sub 2}Ni{sub 2}Sn, and explains why this stannide is close to a magnetic instability. In the system U{sub 2}Pd{sub 2+x}Sn{sub 1-x}, the reduction of the magnetic moment when the palladium composition increases shows the influence of 5f(U) - 4d(Pd) hybridization. In this solid solution, the evolution of the magnetic structure with the composition confirms an empirical law: the uranium magnetic moments are directed perpendicularly to the shortest U-U links. The extension of this study to the new Rare Earth based stannides RE{sub 2}Pd{sub 2,04}Sn{sub 0,96} (RE = Ce, Tb, Dy, Ho, Er) evidenced systematic correlations between complicated magnetic structures. All these compounds present two magnetic transitions, characterized first by a sine-wave modulation, then at lower temperatures by a commensurate magnetic structure. (author)

  15. Forms of Rare Earth Elements in Soils:II.Differentiation of Rare Earth Elements

    Institute of Scientific and Technical Information of China (English)

    ZHUJIAN-GUO; XINGGUANG-XI

    1992-01-01

    The present paper deals mainly with the relationships between the distribution of rare earth elements (REE) in different forms in soils and the atomic number and with the odd-even phenomenon in the distribution of ionic lanthanides in soils.The enrichment tendency of light REE relative to heavy REE in soils was pointed out on the experimental results about the proportions of Ce-group and Y-group elements in different REE forms in soils.Meanwhile,the differentiation of Tm in different soil REE forms was compared and the reasons why Tm is enriched in soils were preliminarily discussed.

  16. 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...

  17. Bacterial Cell Surface Adsorption of Rare Earth Elements

    Science.gov (United States)

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

    2015-12-01

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

  18. Effect of rare-earth (La and Eu) doping on ferroelectric and magnetic properties of magnetoelectric Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Venkata Ramana, E.; Graca, M.P.F.; Valente, M.A. [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810-193 (Portugal)

    2014-09-15

    Polycrystalline Pb(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} (PFN) samples have been synthesized to study the effect of rare-earth ions, La and Eu, on multiferroic physical properties. The synthesis of materials in controlled PbO atmosphere accounted for the pyrochlore free ceramics with tetragonal structure. Small amount (1 at.%) of rare-earth doping resulted in a shrinkage of unit cell volume. The dielectric studies indicated a decrease in phase transition temperature from 375 K to 356 K for La doped ceramics. A well-saturated ferroelectric polarization with a remanent polarization of 8.9 μC/cm{sup 2} was observed for undoped PFN while the doping affected in the large leakage current and higher coercivity. We observed no significant effect of doping on magnetic transition temperatures at low temperatures. Doping with La resulted in reduced magnetoelectric coefficient compared to the undoped value of 9.2 mV/cmOe, due to the poor poling ability. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. CRYSTAL DEFECTS IN PLASMA NITRIDED LAYER CATALYZED BY RARE EARTH

    Institute of Scientific and Technical Information of China (English)

    F.S. Chen; Y.X. Liu; D.K. Liang; L.M. Xiao

    2002-01-01

    The microstructure of plasma nitrided layer catalyzed by rare-earth elements has beenstudied with TEM. The results show that the grains of γ'-Fe4N phase are refinedby rare-earth elements and the plane defects in boundary are increased by rare-earthelements. The addition of rare-earth element increases the bombardment effect andthe number of crystal defects such as vacancies, dislocation loops, twins and stackingfaults in γ'-Fe4N phase and can produce the high-density dislocations in the ferrite ofdiffusion layer at a distance 0. 08mm from the surface. The production of a numberof crystal defects is one of important reasons why rare-earth element accelerates thediffusion of nitrogen atoms during plasma-nitridiug.

  20. 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.

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

    Science.gov (United States)

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

    2009-06-01

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

  2. Study on Competitive Power of Rare Earth Industry in China

    Institute of Scientific and Technical Information of China (English)

    Qian Jiuhong; Li Guoping

    2004-01-01

    China is abundant of rare earth resources, it has been the biggest producer, consumer and supplier. The superiority and the scale within the last 40 years make it possible to develop China's rare earth industry in a higher degree.But the superiority of rare earth resources has not turned into the economic superiority, and the development of rare earth industry in China with high speed does not lead to high benefits. Therefore, it has become the hot point and vital task now how to resolve the main problems of rare earth industry in China and how to make its rare earth industry grow healthily and steadily through transforming resources, adjusting structure, escalating industry, bringing forth new ideas in technology. This article aims at analyzing the competitive power of China's rare earth industry in the application of "Diamond framework, Determinants of National Advantage" written by Michael Porter, the well-known economist,based on the analysis, the author puts forward a strategic proposal to raise the competitive power.

  3. Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

    Science.gov (United States)

    Campos, S.; Denoyer, A.; Jandl, S.; Viana, B.; Vivien, D.; Loiseau, P.; Ferrand, B.

    2004-06-01

    Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

  4. Rotation and magnetism of Earth`s inner core

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, G.A. [Los Alamos National Lab., NM (United States); Roberts, P.H. [Univ. of California, Los Angeles, CA (United States)

    1996-12-13

    Three-dimensional numerical simulations of the geodynamo suggest that a super-rotation of Earth`s solid inner core relative to the mantle is maintained by magnetic coupling between the inner core and an eastward thermal wind in the fluid outer core. This mechanism, which is analogous to a synchronous motor, also plays a fundamental role in the generation of Earth`s magnetic field. 18 refs., 6 figs.

  5. Propulsion and PWR Rapid Response Research and Development (R&R) Support: Delivery Order 0030: Study of Hot Deformation of Nanocomposite Rare Earth Magnets

    Science.gov (United States)

    2006-03-01

    date: 26 Apr 2006. 14. ABSTRACT High performance bulk anisotropic nanograin composite Nd2Fe14B /Fe and Nd2Fe14B /Fe-Co magnets were successfully...deformation, hybrid magnets, interface exchange coupling, nanocomposite, nanograin magnets, nanostructure, Nd2Fe14B , permanent magnets, powder coating...1 High-Performance Nanograin Composite Nd2Fe14B /α-Fe and Nd2Fe14B /Fe-Co Magnets 2 1.1 Magnets prepared by using powder blending technique 2

  6. Advances on Rare Earth Application in Pollution Ecology

    Institute of Scientific and Technical Information of China (English)

    Huang Xiaohua; Zhou Qing; Zhang Guangsheng

    2005-01-01

    The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc. in environment. The authors suggest that the mechanism of rare earth to inducing plant resistance and reducing plant injury is to control biochemical metabolism web in plant cell, to adjust its protection system of free radical, to maintain its photosynthesis, to protect cell membrane system and to carry through its function on mineral metabolism. Meanwhile some problems in the field were discussed as well.

  7. Review and forecast of China rare earth industry (continued)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ 3. Current rare earth export situation a. RE export enterprises To further strengthen administration on export of rare earths and standardize export system, the Ministry of Commerce instituted the "Qualification Standards and Application Procedures for Rare Earth Export Enterprises" in 2006, which regulated the export from production capacity, technologies, safety & environmental protection and credit of enterprises, hence to standardize the export system. There were 47 RE export enterprises announced in common trade in 2006, while it dropped to 41 ones in 2007 and 25 in 2008. There were merely 23 export enterprises in 2009.

  8. Geochemistry of Rare Earth Elements in Aktishikan Gold Deposit, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    袁峰; 周涛发; 岳书仓

    2002-01-01

    The characteristics and the models of rare earth elements in the geolo gical bodies and the hydrothermal water balanced with the adamellite were compre h ensively studied in Aktishikan gold deposit,Nurt area of Altay,Xinjiang.And th e behavior of rare earth elements during metasomatic alteration was discussed by using the isocon method of Grant.The results show that the rare earth elements a re inert during metasomatic alteration,the hydrothermal water has no relation t o the magmatic water,and the gold material sources mainly stem from the wall rock.

  9. 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.

  10. Separation of rare earth elements by tertiary pyridine type resin

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Tatsuya [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)]. E-mail: tasuzuki@nr.titech.ac.jp; Itoh, Keisuke [Graduate School of Material Science and Engineering, Shibaura Institute of Technology, Shibaura, Minato-ku, Tokyo 108-8584 (Japan); Ikeda, Atsushi [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Aida, Masao [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Ozawa, Masaki [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Oarai Engineering Center, Japan Nuclear Cycle Development Institute, Narita-machi, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1393 (Japan); Fujii, Yasuhiko [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2006-02-09

    The novel separation method of rare earth elements by using the tertiary pyridine type resin with methanol and nitric acid mixed solution was developed. The separating operation in this method is very simple and easy, and the waste generation in this method is expected to be low. The adsorption and separation behaviors of rare earth elements were investigated with changing the nitric acid concentration, the methanol concentration, and the alcoholic species. It was confirmed that the rare earth elements can be well separated mutually.

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

    Science.gov (United States)

    Pourarian, F.; Wallace, W. E.

    1979-01-01

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

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

    Science.gov (United States)

    Pourarian, F.; Wallace, W. E.

    1979-01-01

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

  13. Magnetic features in REMeO{sub 3} perovskites and their solid solutions (RE=rare-earth, Me=Mn, Cr)

    Energy Technology Data Exchange (ETDEWEB)

    Moure, Carlos, E-mail: cmoure@icv.csic.es [Instituto de Cerámica y Vidrio, CSIC, Electroceramics Department, Kelsen No. 5, 28049 Cantoblanco, Madrid (Spain); Peña, Octavio [Institut des Sciences Chimiques de Rennes, UMR 6226, Université de Rennes 1, 35042 Rennes (France)

    2013-07-15

    Magnetic hysteresis displacement, thermal inversion of the magnetization, hysteresis loops jumps and crossing branches of hysteresis loops at low magnetic fields are reviewed. Most of these phenomena have been observed in magnetic oxide systems, particularly in perovskite-type manganites and chromites. The paper takes into account structural considerations and different geometrical parameters, such as volume or thin layers. - Highlights: ►Review of both spin reversal phenomena thermal and displacive. ► Study of the crossing branches of the magnetic hysteresis loops. ► Review of the behavior of some stepped hysteresis loops.

  14. Research on Rare Earth Permanent Magnet Electromagnetic Drive in Tobacco Leaf Spring Plate Vibration Sieve System%基于稀土永磁电磁驱动的烟叶簧板式振筛系统的研究

    Institute of Scientific and Technical Information of China (English)

    林河; 祝荣壮; 袁兴

    2016-01-01

    烟草企业在用的烟叶簧板式振筛多为电机驱动,噪声大、能耗高、维护成本大、维护难度高;分析了直线电机原理,引入稀土永磁电磁驱动理论,通过控制器驱动电磁线圈,吸合永磁机构带动簧板往复运动;电磁驱动方式可实现无摩擦、低噪声、低耗能等绿色环保新理念振筛驱动方式,实际运行效果也很好。%The most of tobacco leaf spring plate vibration sieves are driven by motors in the current tobacco factories, such that op-erating noise, high energy consumption, high maintenance cost and maintenance difficulty exist in it. This paper analyses the princi-ple of the linear motor and introduces the theory of rare earth permanent magnet electromagnetic drive into it. The control er electro-magnetic coil and permanent magnetic actuator are used to drive the spring plate reciprocating movement; Electromagnetic drive mode withno friction, low noise, low energy consumption can be realized. It meets the new idea of green environmental protection such as the drive mode of the vibration sieve, its running effect is very good.

  15. 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.

  16. Monolithic Rare Earth Doped PTR Glass Laser Project

    Data.gov (United States)

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

  17. 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.

  18. Prospects for trivalent rare earth molecular vapor lasers for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Krupke, W.F.

    1976-04-12

    The dynamical properties of three types of RE/sup 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/sup 3 +/ and Tb/sup 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.

  19. Synthesis of Polyketone STCO Promoted by Rare Earth Catalyst

    Institute of Scientific and Technical Information of China (English)

    GUO Jintang; ZHENG Yonghui; WANG Bo; TIAN Jing

    2006-01-01

    To lower the cost of polyketone synthesis, rare earth coordinate catalyst was introduced to the copolymerization of carbon monoxide (CO) and styrene (ST) to synthesize aliphatic polyketone STCO.The catalytic system was composed of rare earth neodymium acetate, yttrium acetate,2,2'-bipyridine, p-toluensulfonic acid, cupric p-toluensulfonate, and 1,4-benzoquinone.The catalyst and the copolymer were characterized by infrared spectrum and X-ray photoelectron spectroscopy respectively.The effects of each component of catalytic system and the kinds of rare earth acetates on catalytic activity of copolymerization were investigated.The results show that the proposed rare earth has distinct catalytic activity in the copolymerization of CO and ST and the maximum activity can reach 303.3 gSTCO/(mol·h).

  20. Rare Earth Market Review August 20-31

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Rare earth market still went downward affected by continuous price fall of didymium oxide and didymium mischmetal. However, the market of europium oxide (99.99%) remained stable, with price rose slightly.

  1. Rare Earth Doped Optical Fibre From Oxide Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Minati Chatterjee; Aharon Gedanken; Renata Reisfeld; Ranjan Sen; Mrinmay Pal; Milan Naskar; Mukul Paul; Shyamal Bhadra; Kamal Dasgupta; Dibyendu Ganguli; Tarun Bandyopadhyay

    2003-01-01

    Rare earth (RE) doped optical fibres were fabricated by using RE oxides coated silica nanoparticles. The fibre properties are comparable to those prepared by conventional techniques. The process offers better control over RE incorporation and homogeneity in the preform.

  2. Rare Earth Doped High Temperature Ceramic Selective Emitters

    Science.gov (United States)

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

    1999-01-01

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

  3. China vows equal treatment in rare earth regulation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    BEIJING, July 15 (Xinhua)-- China pledged it will abide by World Trade Organization rules and apply "same policies" to both domestic and overseas companies in rare earth production, processing and export.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  5. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX/sub 2/ (X = Ru, Rh, Ir, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.; Haelg, W.; Kaldis, E.; Greidanus, F.J.A.M.; Buschow, K.H.J.

    1982-01-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield <100> as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu/sub 2/ type Laves phase systems PrX/sub 2/ (X = Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  6. New neutron diffraction results on magnetic properties of the cubic rare earth compounds HoP and PrX2 (X=Ru, Rh, Ir, Pt)

    Science.gov (United States)

    Fischer, P.; Hälg, W.; Kaldis, E.; Greidanus, F. J. A. M.; Buschow, K. H. J.

    1982-09-01

    Neutron diffraction studies performed on polycrystalline, NaCl type HoP in external magnetic fields yield as easy directions of magnetization in the ferromagnetic state. The magnetic ordering of the MgCu2 type Laves phase systems PrX2 (X=Ru, Rh, Ir, Pt) was investigated on powdered samples by means of neutron diffraction. Simple ferromagnetic structures were observed. The determined Curie temperatures confirm bulk measurements, and the values of the ordered magnetic moments indicate crystal field effects.

  7. Rare-earth loaded liquid scintillator (for LENS experiment)

    CERN Document Server

    Barabanov, I R; Kornoukhov, V N; Yanovich, E A; Zatsepin, G T; Danilov, N A; Korpusov, G V; Kostukova, G V; Krylov, Y S; Yakshin, V V

    1999-01-01

    Rare-earth (Yb/Gd) complexes with neutral organophosphorus ligands are briefly discussed for their application in liquid scintillation technique. To evaluate the principal feasibility of rare-earth loaded scintillator, the ytterbium chloride complexes with tri-isoamylphosphine oxides were synthesized. Relative scintillation efficiency (RSE) for two Yb concentrations (78 and 88 g/L) was measured by means of the internal conversion exitation from Cs-137. The results obtained were 50 and 40% respectively.

  8. 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.

  9. CRYSTAL GROWTH OF RARE EARTH COMPOUNDS IN CLOSED SYSTEM

    OpenAIRE

    1991-01-01

    Remarkable improvements have been made on the crystal growth of rare earth pnictides and chalchogenides by the development of new growth technique and the construction of several new equipments for the crystal growth such as electron beam welding system of tungsten crucible provided with large glove box and vacuum HF furnace. This system has really worked on obtaining excellent quality of single crystals and made easier to explore unknown materials of rare earth compounds. Interesting and att...

  10. Rare-earth-ion-doped double-tungstate waveguides

    NARCIS (Netherlands)

    Pollnau, M.

    2007-01-01

    It has been recognized that the monoclinic double tungstates KY(WO4)2, KGd(WO4)2, and KLu(WO4)2 possess a high potential as rare-earth-ion-doped solid-state laser materials, partly due to the high absorption and emission cross-sections of rare-earth ions when doped into these materials. Besides, the

  11. Hydrogen solubility in rare earth based hydrogen storage alloys

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Hirohisa [Tokai Univ., Kanagawa (Japan). School of Engineering; Kuji, Toshiro [Mitsui Mining and Smelting Co. Ltd., Saitama (Japan)

    1999-09-01

    This paper reviews significant results of recent studies on the hydrogen storage properties of rare earth based AB{sub 5} (A: rare earth element, B: transition element) alloys The hydrogen solubility and the hydride formation, typically appeared in pressure-composition isotherms (PCT), are strongly dependent upon alloy composition, structure, morphology and even alloy particle size. Typical experimental results are shown to describe how these factors affect the hydrogen solubility and storage properties.

  12. Determination of rare earth elements in plant protoplasts by MAA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A preliminary study on the speciation of rare earth elements in plant cells has been carried out by molecular activation analysis (MAA). Mesophyll protoplasts of Brassica napus were isolated by enzymatic digestion. After being washed with isosmotic solution containing EDTA for several times, the protoplasts were purified by gradient centrifugation. Then the concentration of rare earth elements (REEs) in the protoplasts was determined by neutron activation analysis. The result shows that REEs can enter the cells of the plant.

  13. X-ray resonant exchange scattering of rare-earth nickel borocarbides

    Energy Technology Data Exchange (ETDEWEB)

    Detlefs, C.

    1997-10-08

    The purpose of this thesis is to investigate the systematics of the microscopic magnetic order within a series of isostructural compounds and, at the same, to develop the relatively young experimental method of x-ray resonant exchange scattering (XRES). In this thesis, the author presents XRES studies of several rare-earth nickel borocarbides, RNi{sub 2}B{sub 2}C. He shows that XRES, similar to the neutron techniques, allows the determination of the orientation of the magnetic moment by measuring the Q-dependence of the scattered intensity of magnetic Bragg reflections. As samples in this study, he chose the recently discovered family of rare-earth nickel borocarbides, RNi{sub 2}B{sub 2}C, which display a wide variety of magnetic structures. Furthermore, in several of these materials, long range magnetic order coexists with superconductivity over some temperature 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. Magnetic Phase Transformation in the RE(Mn0.5B0.5)O3 Perovskites (RE is a Rare Earth Ion, B-Ni, Co)

    OpenAIRE

    Troyanchuk, I.; Szymczak, H.; Samsonenko, N.; Nabialek, A.

    1997-01-01

    A magnetic study of perovskites RE(Mn1-xBx)O3 (RE=Eu, Gd, Tb, Dy, Y ; B=Ni, Co) is reported. It is found that investigated perovskites are nonhomogenous ferromagnets with relatively high Curie temperatures. The magnetic anisotropy of Ni-containing perovskites is much lower than that of Co-containing ones. It is supposed that domains with different charge state of ions and magnetic structure coexist in a wide range of Co- and Mn- concentrations. The metamagnetic behavior has been observed for ...

  16. Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

    Science.gov (United States)

    Ku, Anthony Y.; Dosch, Christopher; Grossman, Theodore R.; Herzog, Joseph L.; Maricocchi, Antonio F.; Polli, Drew; Lipkin, Don M.

    2014-11-01

    Rare-earth (RE) elements are enablers for a wide range of technologies, including high-strength permanent magnets, energy-efficient lighting, high-temperature thermal barrier coatings, and catalysts. While direct material substitution is difficult in many of these applications because of the specific electronic, optical, or electrochemical properties imparted by the individual rare-earth elements, we describe an example from the aviation industry where supply chain optimization may be an option. Ceramic matrix composite engine components require environmental barrier coatings (EBCs) to protect them from extreme temperatures and adverse reactions with water vapor in the hot gas path. EBC systems based on rare-earth silicates offer a unique combination of environmental resistance, thermal expansion matching, thermal conductivity, and thermal stability across the service temperature window. Several pure rare-earth silicates and solid solutions have been demonstrated in EBC applications. However, all rely on heavy rare-earth elements (HREEs) for phase stability. This article considers the possibility of using separation tailings containing a mixture of HREEs as a source material in lieu of using the high-purity HREE oxides. This option arises because the desired properties of RE-silicate EBCs derive from the average cation size rather than the electronic properties of the individual rare-earth cations. Because separation tailings have not incurred the costs associated with the final stages of separation, they offer an economical alternative to high-purity oxides for this emerging application.

  17. Commercial Reserve will Help Rare Earth Industry to Leave Behind Cold Winter

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    As key component in the construction of rare earth strategy reserve system,the rare earth commercial reserve,an initiative advocated by the state government,spontaneously carried out by several major rare earth enterprise groups to target at reform of the supply front for the rare earth industry,formally kicked off.The encouraging news is that,within a matter of one month,affected by news of rare earth commercial reserve,rare earth market prices

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

    Science.gov (United States)

    Huang, Xiang; Zhang, Guochun; Pan, An; Chen, Fengying; Zheng, Chunli

    2016-11-01

    As increasing demand for green energy and high-tech devices grows, so does the rising prospecting of rare earth metals required for their production. Protecting the environment and public health from rare earth element (REE) mining as well as emerging pollutants is urgently required to achieve sustainable development. This study mapped Earth's hidden REE deposits to identify potential contamination hotspots with the aim of preventing its deleterious effects on the environment. We worry that there would be widespread tailing facilities concomitant with serious pollutions, such as the Bayan Obo tailings site, and argue that a tradeoff between the underground REE exploration and environment conservation should be reached as soon as possible.

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

    OpenAIRE

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

    2015-01-01

    It was shown that the divalent rare earth ions (La, Ce, Gd, Tb, Lu, and Y) in cubic sites in alkaline earth fluorides are unstable with respect to electron autodetachment since its d1(eg) ground state is located in the conduction band which is consistent with the general tendency of these ions in various compounds. The localization of doubly degenerate d1(eg) level in the conduction band creates a configuration instability around the divalent rare earth ion that leading to the formation of an...

  20. Structural and magnetic studies on perovskite rare-earth manganites (Nd1-xGdx)0.55Sr0.45MnO3 (x=0, 0.1, 0.3 and 0.5): Observation of two-step magnetization and negative magnetization behavior

    Science.gov (United States)

    Kamel, R.; Tozri, A.; Dhahri, E.; Hlil, E. K.; Bessais, L.

    2017-03-01

    The effect of smaller and heavy rare-earth cation Gd3+(rGd3+=1.107 Å and SGd3+ = 7 / 2) on the magnetic and structural properties of Nd0.55Sr0.45MnO3 has been investigated. The orthorhombic structure (space group, Pnma) evolves from orbital distorted-O" type symmetry (c > a) for x=0 to orbital ordered-O' type (a > c) for x ≥ 0.1 . Diffraction data shows the crucial role of the shear strains involved in the structure. The magnetization measurement shows two magnetic transitions occurring in compounds x≥0.1. Spectacular feature was observed in the heavily Gd-doped sample (x=0.5) such as: the continuous increase of M with high magnetic field, the low value of saturation magnetization at low temperature, the metamagnetic transition, and the presence of exchange bias. These findings are interpreted as the fingerprints of the phase separation. Our result indicates that the martensitic accommodation strain, in addition to quenched disorders, may be an alternative approach to understand the physical phase separation. The interesting feature for x=0.5 sample is the negative magnetization observed at low field. Result is interpreted in terms of two interacting networks, with negative exchange interaction between the (Gd+Nd) and the ferromagnetic Mn lattices. The disappearance of the negative magnetization for magnetic field well below the coercive field ( 0.047 T) suggest that the magnetic properties of x=0.5 behaves as an inhomogeneous ferrimagnet at low field.

  1. New transition metal-rich rare-earth palladium/platinum aluminides with RET{sub 5}Al{sub 2} composition. Structure, magnetism and {sup 27}Al NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Stegemann, Frank; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie

    2015-06-01

    REPd{sub 5}Al{sub 2} compounds with RE = Ce-Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements (RE = Tb-Yb) had not been prepared. We report on the missing members of the REPd{sub 5}Al{sub 2} (RE = Tb-Yb) series as well as on the new REPt{sub 5}Al{sub 2} (RE = Y, Gd-Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi{sub 2}Al{sub 5} type with an anti-arrangement of the T = Pd/Pt and Al atoms. YPd{sub 5}Al{sub 2} and LuPd{sub 5}Al{sub 2}, as well as the respective platinum homologs, YPt{sub 5}Al{sub 2} and LuPt{sub 5}Al{sub 2}, have been characterized also by {sup 27}Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.

  2. Magnetic Storms at Mars and Earth

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Falkenberg, Thea Vilstrup

    In analogy with magnetic storms at the Earth, periods of significantly enhanced global magnetic activity also exist at Mars. The extensive database of magnetic measurements from Mars Global Surveyor (MGS), covering almost an entire solar cycle, is used in combination with geomagnetic activity...... indices at Earth to compare the occurrence of magnetic storms at Mars and Earth. Based on superposed epochs analysis the time-development of typical magnetic storms at Mars and Earth is described. In contradiction to storms at Earth, most magnetic storms at Mars are found to be associated...... with heliospheric current sheet crossings, where the IMF changes polarity. While most storms at the Earth occur due to significant southward excursions of the IMF associated with CMEs, at Mars most storms seem to be associated with the density enhancement of the heliospheric current sheet. Density enhancements...

  3. Magnetic Storms at Mars and Earth

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Falkenberg, Thea Vilstrup

    In analogy with magnetic storms at the Earth, periods of significantly enhanced global magnetic activity also exist at Mars. The extensive database of magnetic measurements from Mars Global Surveyor (MGS), covering almost an entire solar cycle, is used in combination with geomagnetic activity...... indices at Earth to compare the occurrence of magnetic storms at Mars and Earth. Based on superposed epochs analysis the time-development of typical magnetic storms at Mars and Earth is described. In contradiction to storms at Earth, most magnetic storms at Mars are found to be associated...... with heliospheric current sheet crossings, where the IMF changes polarity. While most storms at the Earth occur due to significant southward excursions of the IMF associated with CMEs, at Mars most storms seem to be associated with the density enhancement of the heliospheric current sheet. Density enhancements...

  4. When materials become critical : lessons from the 2010 rare earth crisis

    NARCIS (Netherlands)

    Sprecher, B.

    2016-01-01

    This dissertation is the culmination of over four years research on the rare earth element neodymium in the context of the 2010 REE crisis. Neodymium is a generally recognized ‘critical’ material with a relevant application in the form of NdFeB magnets, both for sustainable energy technologies as we

  5. Mechanisms of anomalous interaction between the intraatomic excitations and conduction electrons in rare-earth intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, K.A. (AN SSSR, Moscow USSR. Kurchatov Inst. (USSR)); Khomskii, D.I. (AN SSSR, Moscow USSR. Lebedev Physical Inst. (USSR))

    1988-12-01

    Essentially atomic electron-polaron mechanism reducing the magnetic moments of rare-earth and actinide elements in intermetallic compounds is proposed. This mechanism is effective for the atoms possessing soft intraatomic excitations in f- and d-channels (Ce,U,Eu,Yb).

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

    Science.gov (United States)

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

    2014-10-15

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

  7. Oxygen trapped by rare earth tetrahedral clusters in Nd{sub 4}FeOS{sub 6}: Crystal structure, electronic structure, and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Qisheng, E-mail: qslin@ameslab.gov [Division of Materials Sciences and Engineering, Ames Laboratory, US-DOE, Ames, IA 50011 (United States); Taufour, Valentin [Division of Materials Sciences and Engineering, Ames Laboratory, US-DOE, Ames, IA 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Zhang, Yuemei [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Wood, Max; Drtina, Thomas; Bud’ko, Sergey L.; Canfield, Paul C. [Division of Materials Sciences and Engineering, Ames Laboratory, US-DOE, Ames, IA 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Miller, Gordon J. [Division of Materials Sciences and Engineering, Ames Laboratory, US-DOE, Ames, IA 50011 (United States); Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)

    2015-09-15

    Single crystals of Nd{sub 4}FeOS{sub 6} were grown from an Fe–S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd{sub 4}MnOSe{sub 6}-type structure (P6{sub 3}mc, a=9.2693(1) Å, c=6.6650(1)Å, V=495.94(1) Å{sup 3}, Z=2), featuring parallel chains of face-sharing [FeS{sub 6×1/2}]{sup 4−} trigonal antiprisms and interlinked [Nd{sub 4}OS{sub 3}]{sup 4+} cubane-like clusters. Oxygen atoms were found to be trapped by Nd{sub 4} clusters in the [Nd{sub 4}OS{sub 3}]{sup 4{sub +}} chains. Structural differences among Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6} and the related La{sub 3}CuSiS{sub 7}− and Pr{sub 8}CoGa{sub 3}-type structures have been described. Magnetic susceptibility measurements on Nd{sub 4}FeOS{sub 6} suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions. - Graphical abstract: Trapping of oxygen in Nd{sub 4} tetrahedral clusters results in the formation of the Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6}, in contrast to the La{sub 3}CuSiS{sub 7}-type oxygen-free Nd{sub 4}FeS{sub 7} and related Pr{sub 8}CoGa{sub 3}-type structures. Complex magnetic frustration inhibits magnetic ordering at low temperature. - Highlights: • Single crystals of Nd{sub 4}FeOS{sub 6} were grown using self-flux method. • Oxygen was found trapped by Nd{sub 4} tetrahedral clusters. • Comparison with two closely related structural types were discussed. • Magnetic measurements revealed antiferromagnetic (AFM) interaction. • VASP calculations confirmed strong magnetic frustration in AFM model.

  8. Application of Rare Earths in Thermal Barrier Coating Materials

    Institute of Scientific and Technical Information of China (English)

    Xueqiang CAO

    2007-01-01

    Rare earths are a series of minerals with special properties that make them essential for applications including miniaturized electronics, computer hard disks, display panels, missile guidance, pollution controlling catalysts,H2-storage and other advanced materials. The use of thermal barrier coatings (TBCs) has the potential to extend the working temperature and the life of a gas turbine by providing a layer of thermal insulation between the metallic substrate and the hot gas. Yttria (Y2O3), as one of the most important rare earth oxides, has already been used in the typical TBC material YSZ (yttria stabilized zirconia). In the development of the TBC materials, especially in the latest ten years, rare earths have been found to be more and more important. All the new candidates of TBC materials contain a large quantity of rare earths, such as R2Zr2O7 (R=La, Ce, Nd,Gd), CeO2-YSZ, RMeAI11O19 (R=La, Nd; Me=Mg, Ca, Sr) and LaPO4. The concept of double-ceramiclayer coatings based on the rare earth materials and YSZ is effective for the improvement of the thermal shock life of TBCs at high temperature.

  9. Alleviation Effects of Rare Earth on Cd Stress to Rape

    Institute of Scientific and Technical Information of China (English)

    马建军; 张淑侠; 朱京涛; 吴贺平

    2004-01-01

    Using rapes as test materials, the fastness expression and alleviation effect of rapes were studied under Cd stress condition, as the rapeseeds were dipped in the single element(La, Ce, Nd, Pr)and mixed rare earth(RE). The results indicate that, under Cd stress, the dry and fresh weight are increased by both the single element and mixed rare earth treatment, and the fastness of rape is improved.The single element of rare earth decreases the Cd content in rape roots and transmits Cd to the edible parts above the ground in which the alleviation effect of Ce is most significant.La treatment takes the second place, so that the poisonous effect of heavy metal Cd is eased.The mixed rare earth doesn't alleviate the assimilation of Cd in rape roots, but accelerates the transfer of Cd to the parts above the ground. The research puts forward that the alleviation of rare earth on Cd stress has connection with the decrease of Ca content.

  10. Absence of significant structural changes near the magnetic ordering temperature in small-ion rare earth perovskite RMnO3

    Science.gov (United States)

    Yu, T.; Tyson, T. A.; Chen, H. Y.; Abeykoon, A. M. M.; Chen, Y.-S.; Ahn, K. H.

    2014-12-01

    Detailed structural measurements on multiple length scales were conducted on a new perovskite phase of ScMnO3, and on orthorhombic LuMnO3 as a benchmark. Complementary density functional theory (DFT) calculations were carried out, and predict that ScMnO3 possesses E-phase magnetic order at low temperature with displacements of the Mn sites (relative to the high temperature state) of ˜0.07 Å, compared to ˜0.04 Å predicted for LuMnO3. However, detailed local, intermediate and long-range structural measurements by x-ray pair distribution function analysis, single crystal x-ray diffraction and x-ray absorption spectroscopy, find no local or long-range distortions on crossing into the low temperature E-phase of the magnetically ordered state. The measurements place upper limits on any structural changes to be at most one order of magnitude lower than DFT predictions and suggest that this theoretical approach does not properly account for the spin-lattice coupling in these oxides and may possibly predict the incorrect magnetic order at low temperatures. The results suggest that the electronic contribution to the electrical polarization dominates and should be more accurately treated in theoretical models.

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

    Science.gov (United States)

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

    2016-03-01

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

  12. Electromagnetic Field Analysis of Rare Earth Permanent Magnet Brushless DC Motor Based on Ansoft%基于 Ansoft 的稀土永磁无刷直流电机的电磁场分析

    Institute of Scientific and Technical Information of China (English)

    谢晓敏; 卜燕梅; 夏佳青

    2015-01-01

    Taking a three-phase six-state rare earth permanent magnet poles brushless DC motor as an analytical model, electromagnetic field simulation were calculated using finite element analysis software Ansoft. And two no-load and load transients were simulated.The magnetic field lines, the magnetic flux density reluc-tance torque and counter electromotive force curve were gotten.The flux density and winding current were simu-lated.Through the work of the two states electromagnetic field simulation results analysis, the cogging torque rip-ple generated due to provide a reliable basis for optimal motor design parameters can be reduced.%以一个三相六状态两极的稀土永磁无刷直流电机作为分析模型,采用Ansoft有限元分析软件对电机电磁场进行了空载和负载两种瞬态的计算和仿真,得到了磁力线、磁通密度、磁阻力矩和反电动势曲线,并对气隙磁密和绕组电流进行了仿真分析。通过对两种工作状态的电磁场仿真结果对比分析,可以减少由于齿槽效应而产生的转矩脉动,为优化电机设计参数提供可靠依据,具有一定的工程意义。

  13. Magnetic and microwave absorption properties of rare earth ions (Sm3+, Er3+) doped strontium ferrite and its nanocomposites with polypyrrole

    Science.gov (United States)

    Luo, Juhua; Xu, Yang; Mao, Hongkai

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm3+, Er3+) were prepared via a sol-gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2-38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50-100 nm after coating with PPy. In the magnetization for the PPy/SrSm0.3Fe11.7O19 (SrEr0.3Fe11.7O19) composites, the coercivity (Hc) of the composites both increased compared with the undoped composite while the saturation magnetization (Ms) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of -24.01 dB in 13.8 GHz at 3.0 mm. And its width (<-10 dB) has reached 7.2 GHz which has covered the whole Ku band.

  14. Magnetic and microwave absorption properties of rare earth ions (Sm{sup 3+}, Er{sup 3+}) doped strontium ferrite and its nanocomposites with polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Juhua, E-mail: luojuhua@163.com [School of Materials Engineering, Yancheng Institute of Technology, Yancheng 224051 (China); Xu, Yang; Mao, Hongkai [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-05-01

    M-type strontium ferrite substituted by RE (RE=Sm{sup 3+}, Er{sup 3+}) were prepared via a sol–gel method. Polypyrrole (PPy)/ferrite nanocomposites (with 20 wt% ferrite) were prepared by in situ polymerization method in the presence of ammonium persulfate. Effect of the substituted RE ions on structure, magnetic properties and microwave absorption properties were investigated by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. All XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. The crystallite size of synthesized particle is within the range of 22.2–38.1 nm. The structural in character of the composites were investigated with FT-IR analysis. It shows that the ferrite successfully packed by PPy. TEM photographs show that the particle size had grown up to 50–100 nm after coating with PPy. In the magnetization for the PPy/SrSm{sub 0.3}Fe{sub 11.7}O{sub 19} (SrEr{sub 0.3}Fe{sub 11.7}O{sub 19}) composites, the coercivity (H{sub c}) of the composites both increased compared with the undoped composite while the saturation magnetization (M{sub s}) appeared opposite change with different RE ions. Considering the electromagnetic loss and impedance matching comprehensively, the Er-doped ferrite/PPy composite got the better microwave absorption performance with the maximum RL value of −24.01 dB in 13.8 GHz at 3.0 mm. And its width (<−10 dB) has reached 7.2 GHz which has covered the whole Ku band. - Highlights: • The influence of RE ions on the structure of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on the magnetic properties of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • The influence of RE ions on electromagnetic losses of PPy/SrRE{sub 0.3}Fe{sub 11.7}O{sub 19} is discussed. • PPy/SrEr{sub 0.3}Fe{sub 11.7}O{sub 19} possessed the excellent absorption property.

  15. Examination of Plasma Nitriding Microstructure with Addition of Rare Earths

    Institute of Scientific and Technical Information of China (English)

    张津

    2004-01-01

    Medium-carbon alloy steel was plasma nitrided with rare earths La,Ce and Nd into the nitriding chamber respectively.The nitriding layer microstructures with and without rare earths were compared using optical microscope,normal SEM and high resolution SEM,as well as TEM.It was found that the extent of the influence on plasma nitriding varies with different contents of rare earth.The effect of plasma nitriding is benefit from adding of Ce or Nd.The formation of hard and brittle phase Fe2-3N can be prevented and the butterfly-like structure can be improved by adding Ce or Nd.However,pure La may prevent the diffusion of nitrogen and the formation of iron nitride,and reduce the depth of diffusion layer.

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Inoue, Katsutoshi; Alam, Shafiq

    2013-10-01

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

  19. Optical Frequency Comb Spectroscopy of Rare Earth Atoms

    Science.gov (United States)

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

    2013-05-01

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

  20. Study on Microstructure of Alumina Based Rare Earth Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Analysis techniques such as SEM, TEM and EDAX were used to investigate the microstructure of rare earth reinforced Al2O3/(W, Ti)C ceramic composite. Chemical and physical compatibility of the composite was analyzed and interfacial microstructure was studied in detail. It is found that both Al2O3 and (W, Ti)C phases are interlaced with each other to form the skeleton structure in the composite. A small amount of pores and glass phases are observed inside the material which will inevitably influence the physical and mechanical property of the composite. Thermal residual stresses resulted from thermal expansion mismatch can then lead to the emergence of dislocations and microcracks. Interfaces and boundaries of different types are found to exist inside the Al2O3/(W, Ti)C rare earth ceramic composite, which is concerned with the addition of rare earth element and the extent of solid solution of ceramic phases.

  1. Trifunctional Polymeric Nanocomposites Incorporated with Fe₃O₄/Iodine-Containing Rare Earth Complex for Computed X-ray Tomography, Magnetic Resonance, and Optical Imaging.

    Science.gov (United States)

    Wang, Xin; Tu, Mengqi; Yan, Kai; Li, Penghui; Pang, Long; Gong, Ying; Li, Qing; Liu, Ruiqing; Xu, Zushun; Xu, Haibo; Chu, Paul K

    2015-11-11

    In this study, a novel polymerizable CT contrast agent integrating iodine with europium(III) has been developed by a facile and universal coordination chemistry method. The Fe3O4 nanoparticles are then incorporated into this iodine-containing europium complex by seed-emulsifier-free polymerization. The nanocomposites combining the difunctional complex and superparamagnetic Fe3O4 nanoparticles, which have uniform size dispersion and high encapsulation rate, are suitable for computed X-ray tomography (CT), magnetic resonance imaging (MRI), and optical imaging. They possess good paramagnetic properties with a maximum saturation magnetization of 2.16 emu/g and a transverse relaxivity rate of 260 mM(-1) s(-1), and they exhibit obvious contrast effects with an iodine payload less than 4.8 mg I/mL. In the in vivo optical imaging assessment, vivid fluorescent dots can be observed in the liver and spleen by two-photon confocal scanning laser microscopy (CLSM). All the results showed that nanocomposites as polymeric trifunctional contrast agents have great clinical potential in CT, MR, and optical imaging.

  2. Crystal structure and magnetic properties of the RCo{sub 5-x}Ga{sub x} (x=1, 1.5,2,3,4) and RCo{sub 4-x}FeGa{sub x}(x=1,2) compounds (R=rare eart earth)

    Energy Technology Data Exchange (ETDEWEB)

    Routsi, C. [Democritus Univ. of Thrace, Xanthi (Greece). Dept. of Electrical Engineering

    1998-07-24

    X-ray powder diffraction data of the RCo{sub 5-x}Ga{sub x} compounds indicate that single-phase samples of the CaCu{sub 5} type structure exist up to the composition RCo{sub 3}Ga{sub 2}. The compounds with light rare earths are ferromagnets while those with heavy rare earths are ferrimagnets. The introduction of Fe into the RCo{sub 5-x}Ga{sub x} compounds has an important effect on the magnetic properties. (orig.) 17 refs.

  3. Structure of Rare-earth/Alkali Halide Complexes

    Science.gov (United States)

    Akdeniz, Z.; Önem, Z. Çiçek; Tosia, M. P.

    2001-11-01

    Vapour complex formation of rare-earth halides with alkali halides strongly increases the volatility of these compounds. We evaluate the structure taken by such complexes having the chemical formulas MRX4, M2RX5 and M3RX6, where X = F or Cl and typically M = Li or Na and R = La. The roles played by the two types of metal atom is investigated in MRX4 complexes by also taking M = K, Rb or Cs and R = Gd or Lu. The main predictions that emerge from our calculations are as follows: (i) in MRX4 a fourfold coordination of the rare-earth atom is accompanied by twofold or threefold coordination of the alkali atom, the energy difference in favour of the twofold-coordination state being about 0.3 eV in the case of the LiF complexing agent but even changing sign as the ionic radius of either the alkali or the halogen is increased; (ii) in M2RX5 a fivefold coordination of the rare-earth atom is energetically more stable than a fourfold one, by again not more than about 0.3 eV; (iii) in M3RX6 the fivefold and sixfold coordinations of the rare-earth atom are energetically competitive; and (iv) in both M2RX5 and M3RX6 each coordination state can be realized in various forms that differ in detail but are close in energy. Bond fluctuations and disorder around the rare-earth atom can be expected to be a general feature at elevated temperatures, both in the vapour and in liquid rare-earth/alkali halide mixtures.

  4. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er )

    Science.gov (United States)

    Dun, Z. L.; Trinh, J.; Li, K.; Lee, M.; Chen, K. W.; Baumbach, R.; Hu, Y. F.; Wang, Y. X.; Choi, E. S.; Shastry, B. S.; Ramirez, A. P.; Zhou, H. D.

    2016-04-01

    We present the structural and magnetic properties of a new compound family, Mg2 RE3 Sb3 O14 (RE =Gd ,Dy ,Er ), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE =Gd , we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE =Dy , LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE =Er , two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative X Y system.

  5. Thermal Expansion and Thermal Conductivity of Rare Earth Silicates

    Science.gov (United States)

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

    2006-01-01

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

  6. Integrated Automation System for Rare Earth Countercurrent Extraction Process

    Institute of Scientific and Technical Information of China (English)

    柴天佑; 杨辉

    2004-01-01

    Lower automation level in industrial rare-earth extraction processes results in high production cost, inconsistent product quality and great consumption of resources in China. An integrated automation system for extraction process of rare earth is proposed to realize optimal product indices, such as product purity,recycle rate and output. The optimal control strategy for output component, structure and function of the two-gradcd integrated automation system composed of the process management grade and the process control grade were discussed. This system is successfully applied to a HAB yttrium extraction production process and was found to provide optimal control, optimal operation, optimal management and remarkable benefits.

  7. Rotation and Magnetism of Earth's Inner Core

    Science.gov (United States)

    Glatzmaier; Roberts

    1996-12-13

    Three-dimensional numerical simulations of the geodynamo suggest that a super- rotation of Earth's solid inner core relative to the mantle is maintained by magnetic coupling between the inner core and an eastward thermal wind in the fluid outer core. This mechanism, which is analogous to a synchronous motor, also plays a fundamental role in the generation of Earth's magnetic field.

  8. Effect of Jahn-Teller Mn/sup 3 +/ ion on magnetic properties and spin-reorientation transitions in rare-earth orthoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Kadomtseva, A.M.; Bostrem, I.G.; Krynetskij, I.B.; Moskvin, A.S.; Ovchinnikova, T.L.; Terziev, V.G. (Ural' skij Gosudarstvennyj Univ., Sverdlovsk (USSR))

    1982-08-01

    A magnetic behavior of manganese-substituted orthoferrites of dysprosium and erbium, for which various types of spin-reorientation transitions (Gsub(x)Fsub(z) ..-->.. Gsub(z)Fsub(x), Gsub(z) Fsub(x) ..-->.. Gsub(y), Gsub(x)Fsub(z) ..-->.. Gsub(y)) were observed, has been studied in the temperature range from 2 up to 600 K. The microscopic theoretical analysis of manganese-substituted orthoferrites has been carried out taking into account peculiarities of the Jahn-Teller effect for the impurity Mn/sup 3 +/ ion. It has been shown that the appearance of reorientation transitions from a weak-ferromagnetic state and antiferromagnetic one (the Morine type transition), observed during the replacement of a part of Fe/sup 3 +/ ions on Mn/sup 3 +/ ions, is connected with the fact, that one-ion anisotropy of Mn/sup 3 +/ stabilizes antiferromagnetic spin structure of Gy. In the (ac)-plane the one-ion Mn/sup 3 +/ anisotropy changes in the orthoferrite series stabilizing Gsub(x)Fsub(z) at the beginning of the series and Gsub(z)Fsub(x) at the end of it. The phase diagram of temperature reorientation as a function of Mn/sup 3 +/ ion concentration has been built up.

  9. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er).

    Science.gov (United States)

    Dun, Z L; Trinh, J; Li, K; Lee, M; Chen, K W; Baumbach, R; Hu, Y F; Wang, Y X; Choi, E S; Shastry, B S; Ramirez, A P; Zhou, H D

    2016-04-15

    We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.

  10. Trace Level Rare Earth Elements Separation From Gram Scale Uranium by Calcium Fluoride Coprecipitation

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiu-feng

    2013-01-01

    In the fission yield measurement of rare earth elements of uranium induced by neutron,and the analysis of rare earth elements in spent fuel,the separation of trace rare earth elements from a large number of uranium has very important significance.We separated trace level rare earth elements from gram scale uranium by calcium fluoride coprecipitation in this paper.

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

    Science.gov (United States)

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

    2014-02-01

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

  12. Recovery and separation of rare Earth elements using salmon milt.

    Directory of Open Access Journals (Sweden)

    Yoshio Takahashi

    Full Text Available Recycling rare earth elements (REEs used in advanced materials such as Nd magnets is important for the efficient use of REE resources when the supply of several REEs is limited. In this work, the feasibility of using salmon milt for REE recovery and separation was examined, along with the identification of the binding site of REEs in salmon milt. Results showed that (i salmon milt has a sufficiently high affinity to adsorb REEs and (ii the adsorption capacity of the milt is 1.04 mEq/g, which is comparable with that of commercial cation exchange resin. Heavier REEs have higher affinity for milt. A comparison of stability constants and adsorption patterns of REEs discussed in the literature suggests that the phosphate is responsible for the adsorption of REE in milt. The results were supported by dysprosium (Dy and lutetium (Lu LIII-edge extended x-ray absorption fine structure (EXAFS spectroscopy. The REE-P shell was identified for the second neighboring atom, which shows the importance of the phosphate site as REE binding sites. The comparison of REE adsorption pattern and EXAFS results between the milt system and other adsorbent systems (cellulose phosphate, Ln-resin, bacteria, and DNA-filter hybrid revealed that the coordination number of phosphate is correlated with the slope of the REE pattern. The separation column loaded with milt was tested to separate REE for the practical use of salmon milt for the recovery and separation of REE. However, water did not flow through the column possibly because of the hydrophobicity of the milt. Thus, sequential adsorption-desorption approach using a batch-type method was applied for the separation of REE. As an example of the practical applications of REE separation, Nd and Fe(III were successfully separated from a synthetic solution of Nd magnet waste by a batch-type method using salmon milt.

  13. Promising wastewater treatment using rare earth-doped nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-15

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

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

    Science.gov (United States)

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

    1955-01-01

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

  16. Automation System in Rare Earths Countercurrent Extraction Processes

    Institute of Scientific and Technical Information of China (English)

    贾江涛; 严纯华; 廖春生; 吴声; 王明文; 李标国

    2001-01-01

    Based on the countercurrent extraction theory for optimized designing and simulating, the rare earth separation processes, the selection of the detecting points (stages) and on-line analysis for elements, the simulation of open loop response and its response speed, the diagnosis and the regulative prescription for running the solvent extraction cascades were studied.

  17. Systematic hardness measurements on some rare earth garnet crystals

    Indian Academy of Sciences (India)

    D B Sirdeshmukh; L Sirdeshmukh; K G Subhadra; K Kishan Rao; S Bal Laxman

    2001-10-01

    Microhardness measurements were undertaken on twelve rare earth garnet crystals. In yttrium aluminium garnet and gadolinium gallium garnet, there was no measurable difference in the hardness values of pure and nominally Nd-doped crystals. The hardness values were correlated with the lattice and elastic constants. An analysis of hardness data in terms of the interatomic binding indicated a high degree of covalency.

  18. Primary Results of New Rare Earth Materials for Hongti Grape

    Institute of Scientific and Technical Information of China (English)

    He Qiong; Gu Jiangyuan; Wang Jiachen

    2004-01-01

    New rare earth (RE) materials including RE phosphate as base fertilizer, bioactive RE micro-fertilizer and RE entire plant nutrition agent as topdressing fertilizer are treated on Hongti grope.The result showes that the plant leaves become thicker, the color is dark green, the plant disease index is lower, and the sugar content significantly increases.

  19. Strategy of Development of Rare Earth Industry in China

    Institute of Scientific and Technical Information of China (English)

    Su Wenqing

    2004-01-01

    This work introduced the current situation of the development of domestic and foreign rare earths (RE) industry, discussed the strategic position of RE industry in China, analyzed the problems existing in the course of RE industry development, made strategic thought about the transference from resource advantage to economic advantage, and put forward strategic suggestions about the development of RE industry in our country.

  20. 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.

  1. 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

  2. XU Guangxian: Father of Chinese rare earths chemistry

    Institute of Scientific and Technical Information of China (English)

    XIN Ling

    2009-01-01

    @@ Decades ago, he invented a cascade extraction theory and technique that have greatly facilitated the production of the so-called "industrial vitamins," shifting China's role from a low-profit exporter of raw ores to the world's dominant supplier of separated individual rare earth compounds and metals in high purity.

  3. Complex Electronic Structure of Rare Earth Activators in Scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-27

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

  4. Model for the magnetic phases observed at low temperatures in reduced YBa2Cu3O6+x materials with Al substitution for Cu or rare earth ions for Ba

    DEFF Research Database (Denmark)

    Andersen, N.H.; Uimin, G.

    1997-01-01

    From a classical statistical model it is shown that the low temperature antiferromagnetic AFII phase, observed in reduced YBa2Cu3O6+x type materials with Al in the CuOx basal plane or rare earth on the Ba site, results from an effective ferromagnetic coupling between adjacent CuO2 double layers...

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Announcement of Resolutions at the 15th Meeting of the 3rd Session of the Board of Directors of Baogang Rare Earth(continued)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ 4. Proposal on Production Expansion of Baotou Rewin Rare Earth Metallic Materials Co., Lid To further enlarge production capacity of neodymium (didymium) metal of Baotou Rewin Rare Earth Metallic Materials Co., Ltd, which is a holding company of Baogang Rare Earth (Baogang Rare Earth holds 58.42% of the shares of Rewin), enhance local utilization rate of neodymium (didymium) oxide inside Baogang Rare Earth and ensure raw materials supply for future development of NdFeB magnetic materials of Baogang Rare Earth, Baogang Rare Earth approves the project of "Investment of Rewin in production expansion of 3,000 tons of neodymium (didymium) metal per annum". Production capacity of neodymium (didymium) metal of Rewin will approach 8,000 tons/year.

  8. Magnetic and dielectric properties of rare earth substituted Ni{sub 0.5}Zn{sub 0.5}Fe{sub 1.95}R{sub 0.05}O{sub 4} (R = Pr, Sm and La) ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rakesh Kumar, E-mail: rakeshsinghpu@gmail.com [Aryabhatta Centre for Nanoscience & Nanotechnology, Aryabhatta Knowledge University, Patna 800001 (India); Department of Physics, Patna Women' s College, Patna University, Patna 800001 (India); Shah, Jyoti; Kotnala, R.K. [Multiferroics and Magnetics, CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2016-08-15

    Highlights: • Formation of pure phase rare earth substituted nanocrystalline Ni{sub 0.5}Zn{sub 0.5}R{sub 0.05}Fe{sub 1.95}O{sub 4} (R = La, Pr and Sm) using citrate precursor method and at low annealing temperature of 450 °C. • Systematic changes in the lattice parameters with particle size and significant changes in magnetic parameters in the rare-earth substituted nanoferrites. • Large ionic radii of rare earth ions triggering local distortion and inducing softening of super exchange interaction. Decreasing order of coercivity and magnetization due to less number of domain walls and its movement in the direction of the magnetic field. • Dielectric measurements at higher frequency range (100 Hz–1 MHz) shows that these substituted ferrites exhibit small dielectric loss, which is suitable for high frequency applications. - Abstract: Ni{sub 0.5}Zn{sub 0.5}Fe{sub 1.95}R{sub 0.05}O{sub 4} nanoparticles (R = Pr, Sm and La) have been synthesized by citrate precursor method and annealed at 450 °C. All the samples were found to be in single phase. The lattice constants and crystallite size decreases with rare earth substitution (25 nm, 23 nm, 11 nm and 9 nm) due to strain produced in spinel lattice. Saturation magnetization and coercivity of ferrite significantly decreases (50.69 emu/g, 32.17 emu/g. 30.21 emu/g and 34.65 emu/g respectively) with rare earth substitution. The substitution of large ionic radius rare earth ions in Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} results in distortion and induces a softening of magnetic exchange interaction. The dielectric measurements at higher frequency range (100 Hz–1 MHz) shows that these substituted ferrites exhibits low dielectric loss, which is suitable for high frequency applications.

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

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

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

  10. The Evolution of the Earth's Magnetic Field.

    Science.gov (United States)

    Bloxham, Jeremy; Gubbins, David

    1989-01-01

    Describes the change of earth's magnetic field at the boundary between the outer core and the mantle. Measurement techniques used during the last 300 years are considered. Discusses the theories and research for explaining the field change. (YP)

  11. Magnetic Reconnection in the Earth's Magnetosphere

    Science.gov (United States)

    Tsurutani, B. T.; Lakhina, G. S.

    1997-01-01

    The process of magnetic reconnection plays an important role during the interaction of the solar wind with the Earth's magnetosphere which leads to the exchange of mass, momentum, and energy between these two highly conducting plasmas.

  12. Chinalco and China National Administration of Coal Geology Jointly Built Guangxi Rare Earth Industrial Base

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>On June 3,Chinalco and China National Administration of Coal Geology signed cooperation agreement for strategic cooperation&cooperation agreement between Chinalco Guangxi Nonferrous Rare Earth Development Company and Xuzhou Jin Shi Pengyuan Rare Earth Material Factory.According to the agreement,both sides would jointly support Chinalco Guangxi Nonferrous Rare Earth Development Company and Xuzhou Jin Shi Pengyuan Rare Earth Material Factory to carry out comprehensive cooperation covering rare

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

    Directory of Open Access Journals (Sweden)

    Yliruokanen, I.

    1995-12-01

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

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

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

    The angular correlation of the photons emitted when positrons annihilate with electrons has been studied in single crystals of the rare-earth metals Y, Gd, Tb, Dy, Ho, and Er, and in a single crystal of an equiatomic alloy of Ho and Er. A comparison of the results for Y with the calculations...... of Loucks shows that the independent-particle model gives a good first approximation to the angular distribution, although correlation effects probably smear out some of the structure. The angular distributions from the heavy rare-earth metals are very similar to that from Y and can be understood...... qualitatively in terms of the relativistic augmented-plane-wave calculations by Keeton and Loucks. The angular distributions in the c direction in the paramagnetic phases are characterized by a rapid drop at low angles followed by a hump, and these features are associated with rather flat regions of Fermi...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-15

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

  16. Thermochemistry of Rare Earth Silicates for Environmental Barrier Coatings

    Science.gov (United States)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

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

  17. Research of Optical Performance On Rare-Earth Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    Li Baojun; Zhou Meng; Yang Tao; Zhou Yao; Fu Li; Li Tiansi; YangShilong

    2004-01-01

    The rare-earth optical fiber is made of organic material and inorganic rare earth material.It can be used to absorb and transfer solar energy.When sunlight irradiates, it may absorb and transfer solar energy automatically; while at night or without sunlight it may give out light and play role of decoration.By utilizing high transmissivity of organic material and heat-resisting performance of inorganic material, we know the reorganization of material performance under the melting condition, and make empty core bear the high temperature of 150 ~200 ℃.When the light spreads in light guide, some light energy travels along the direction of light guide, and is introduced in the room directly.Another part of light energy is absorbed and stored by light guide, and can release light again after 8 ~ 12 h.

  18. Calcination-Digestion-Desliming of Phosphorus Ore Bearing Rare Earth

    Institute of Scientific and Technical Information of China (English)

    Zhang Qin; Zhang Jie; Wang Jing; Qiu Yue qin

    2004-01-01

    The recoveries of phosphorus and RE of ore from Zhijin in Guizhou were studied.The influences of the calcination temperature, resident time, the digested time and water volume of the calcinating on concentrate yield by desliming were also investigated by orthogonal design.Appropriate calcination temperature is initial condition that makes carbonate mineral decomposition.The recovery of phosphorus is 83.02% and rare earth is 90.56% in phosphorus concentrate when calcined temperature is 900 ℃, other conditions include: calcined time is 30 min, digestion water volume is 300 ml, digestion time is 20 min.The results show that the pre-treatment of the ore is favorable for the separation and enrichment of rare earth from phosphorus ore, and a process of calcination-digestion-desliming was promised.

  19. Review of Studies on Rare Earth against Plant Disease

    Institute of Scientific and Technical Information of China (English)

    慕康国; 张文吉; 崔建宇; 张福锁; 胡林

    2004-01-01

    Agricultural application of rare earth (RE) has been generalized for several decades, and it is involved in crops, vegetables and stock raising in China. However, all the researches on RE mainly focus on the fields such as plant physiological activity, physiological and biochemical mechanism, sanitation toxicology and environmental security. Plant protection by using RE and the induced resistance of plant against diseases were summarized. The mechanism of rare earth against plant disease is highlighted, which includes following two aspects. First, RE elements can control some phytopathogen directly and reduce its virulence to host plant. Another possibility is that RE elements can affect host plant and induce the plant to produce some resistance to disease.

  20. Observation of anomalous phonons in orthorhombic rare-earth manganites

    Science.gov (United States)

    Gao, P.; Chen, H. Y.; Tyson, T. A.; Liu, Z. X.; Bai, J. M.; Wang, L. P.; Choi, Y. J.; Cheong, S.-W.

    2010-12-01

    We observe the appearance of a phonon near the lock-in temperature in orthorhombic REMnO3 (RE denotes rare earth) (RE: Lu and Ho) and anomalous phonon hardening in orthorhombic LuMnO3. The anomalous phonon occurs at the onset of spontaneous polarization. No such changes were found in incommensurate orthorhombic DyMnO3. These observations directly reveal different electric polarization mechanisms in the E-type and incommensurate-type orthorhombic REMnO3.

  1. POLYMERIZATION MECHANISM OF DIENES WITH HOMOGENEOUS RARE EARTH CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    JIN Yingtai; ZHANG Xitian; PEI Fengkui; WU Yue

    1990-01-01

    The reaction mechanisms ofdiene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of 1H- NM R, one- and two- dimensions 13C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η4-diene (cis- (→)trans- )and η3-allyl (syn- (→)anti- ).

  2. Advances in Rare Earth Application to Semiconductor Materials and Devices

    Institute of Scientific and Technical Information of China (English)

    屠海令

    2004-01-01

    The development of rare earths (RE) applications to semiconductor materials and devices is reviewed. The recent advances in RE doped silicon light emitting diodes (LED) and display materials are described. The various technologies of incorporating RE into semiconductor materials and devices are presented. The RE high dielectric materials, RE silicides and the phase transition of RE materials are also discussed. Finally, the paper describes the prospects of the RE application to semiconductor industry.

  3. Coherent optical ultrasound detection with rare-earth ion dopants

    CERN Document Server

    Tay, Jian Wei; Longdell, Jevon

    2010-01-01

    We describe theoretical and experimental demonstration for optical detection of ultrasound using a spectral hole engraved in cryogenically cooled rare-earth ion doped solids. Our method utilizes the dispersion effects due to the spectral hole to perform phase to amplitude modulation conversion. Like previous approaches using spectral holes it has the advantage of detection with large \\'etendue. The method also has the benefit that high sensitivity can be obtained with moderate absorption contrast for the spectral holes.

  4. High photoluminescence efficiency in polymer containing rare earth

    Institute of Scientific and Technical Information of China (English)

    Zhefu Wu; Qidan Ling; Xugang Shi; Jiangxin Zhang; Guangxin Zhu

    2005-01-01

    @@ Three novel kinds of polymers containing rare earth europium have been synthesized and the integrating sphere technique was employed to measure the absolute photoluminescence (PL) efficiency. The PL efficiencies were found to be up to about 40%, which indicates the potential usage in organic light emitting devices (OLED). The energy transfer from ligand to Eu ions and the 5D0 → 7F2 transition of Eu3+ were analyzed under the PL process.

  5. Rare-earth ions doped transparent oxyfluoride glass-ceramics

    OpenAIRE

    2010-01-01

    In recent years, rare-earth ions doped transparent oxyfluoride glass-ceramics have attracted great attentions for their low phonon energy environments of fluoride nanocrystals and high chemical and mechanical stabilities of oxide glassy matrix. In this chapter, firstly, the crystallization behaviors of the transparent glassceramics containing CaF2 nanocrystals are presented to demonstrate the controllable microstructure evolution of nano-composites. Secondly, the optical properties of the new...

  6. Experimental Temperature and Heat Capacity in Rare Earth Nuclei

    Science.gov (United States)

    Melby, E.; Bergholt, L.; Guttormsen, M.; Hjorth-Jensen, M.; Ingebretsen, F.; Messelt, S.; Rekstad, J.; Schiller, A.; Siem, S.; Ødegård, S. W.

    Temperature and heat capacity for the rare earth nuclei 162Dy, 166Er and 172Yb have been extracted from experimental data at the Oslo Cyclotron Laboratory (OCL). The starting point to determine thermodynamical quantities is the density of levels as a function of excitation energy. The density of accessible levels in the (3He,α γ)-reaction has been extracted from measured γ-spectra.

  7. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    OpenAIRE

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

    2010-01-01

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

  8. Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Madhavi Z [ORNL; Fox, Dr. Richard V [Idaho National Laboratory (INL); Miziolek, Andrzej W [United States Army Research Laboratory; DeLucia, Frank C [United States Army Research Laboratory; Andre, Nicolas O [ORNL

    2015-01-01

    There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in real-world complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

  9. Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Madhavi Z [ORNL; Fox, Dr. Richard V [Idaho National Laboratory (INL); Miziolek, Andrzej W [United States Army Research Laboratory; DeLucia, Frank C [United States Army Research Laboratory; Andre, Nicolas O [ORNL

    2015-01-01

    There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

  10. Spectral Analysis of Rare Earth Elements using Laser-Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Madhavi Z. Martin; Robert V. Fox; Andrzej W. Miziolek; Frank C. DeLucia, Jr.; Nicolas Andre

    2001-05-01

    There is growing interest in rapid analysis of rare earth elements (REEs) both due to the need to find new natural sources to satisfy increased demand in their use in various electronic devices, as well as the fact that they are used to estimate actinide masses for nuclear safeguards and nonproliferation. Laser-Induced Breakdown Spectroscopy (LIBS) appears to be a particularly well-suited spectroscopy-based technology to rapidly and accurately analyze the REEs in various matrices at low concentration levels (parts-per-million). Although LIBS spectra of REEs have been reported for a number of years, further work is still necessary in order to be able to quantify the concentrations of various REEs in realworld complex samples. LIBS offers advantages over conventional solution-based radiochemistry in terms of cost, analytical turnaround, waste generation, personnel dose, and contamination risk. Rare earth elements of commercial interest are found in the following three matrix groups: 1) raw ores and unrefined materials, 2) as components in refined products such as magnets, lighting phosphors, consumer electronics (which are mostly magnets and phosphors), catalysts, batteries, etc., and 3) waste/recyclable materials (aka e-waste). LIBS spectra for REEs such as Gd, Nd, and Sm found in rare earth magnets are presented.

  11. Existing State and Partitioning of Rare Earth on Weathered Ores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The existing state and partitioning of rare earth (RE) on weathered ores in Longnan County (LN), Xingfeng County(XF) and Ninghua County(NH) were characterized systematically by standard geological analytical methods. It is found that RE in the weathered rare earth ores exist as four phases: (a) water soluble, (b) ion-exchangeable, (c) colloidal sediment (oxides), (d) minerals, in which mainly as ion exchangeable phase, accounting for nearly 80% of total RE,with about 20% in the form of colloid sediment phase and mineral phase, but very little as aqueous soluble phase. These rare earth partitioning were mainly chosen mid-heavy RE elements, occupying above 60%, but not equal in the four phases. The mid-heavy RE elements were primarily enriched in the ion exchangeable phase up to 40%, while the containment of cerium dioxide is below 2%. The cerium deficiency occurs in the ion exchangeable phase in weathered ore. It results from that the Ce3+ is oxidized into Ce4+ and changes into CeO2. For LN ore, the containment of Y is high in weathered ore because Y-minerals are abundant in original rock.

  12. Preparation of mixed rare earths modified chitosan for fluoride adsorption

    Institute of Scientific and Technical Information of China (English)

    梁鹏; 张艺; 汪东风; 徐莹; 罗斓

    2013-01-01

    This paper described the fluoride removal from water using a new adsorbent namely mixed rare earths modified chitosan (CR). Mixed rare earths mainly contained La followed by Ce which was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). La(III)-modified chitosan (CL) was also prepared as control. For the batch technique, the effects of various parameters such as contact time, pH, adsorbent dose, initial fluoride concentration and co-ions on fluoride adsorption were studied. Fourier trans-form infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to characterize adsorbents. It was observed that the fluo-ride adsorption capacity of CR (3.72 mgF-/g) was higher than CL (3.16 mgF-/g) at 2 h. The presence of co-ions such as bicarbonate and carbonate greatly affected the fluoride adsorption from water. Characterization experiments indicated the successful chelation between mixed rare earths and chitosan. The possible fluoride adsorption mechanism of CR was explained by a chemical reaction.

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

    Institute of Scientific and Technical Information of China (English)

    Nilanjana Das; Devlina Das

    2013-01-01

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

  14. The valence and spectral properties of rare-earth clusters

    CERN Document Server

    Peters, L; Litsarev, M S; Katsnelson, A Delin M I; Kirilyuk, A; Johansson, B; Sanyal, B; Eriksson, O

    2016-01-01

    The rare-earths are known to have intriguing changes of the valence, depending on chemical surrounding or geometry. Here we make predictions from theory that combines density functional theory with atomic multiplet-theory, on the transition of valence when transferring from the atomic divalent limit to the trivalent bulk, passing through different sized clusters, of selected rare-earths. We predict that Tm clusters show an abrupt change from pure divalent to pure trivalent at a size of 6 atoms, while Sm and Tb clusters are respectively pure divalent and trivalent up to 8 atoms. Larger Sm clusters are argued to likely make a transition to a mixed valent, or trivalent, configuration. The valence of all rare-earth clusters, as a function of size, is predicted from interpolation of our calculated results. We argue that the here predicted behavior is best analyzed by spectroscopic measurements, and provide theoretical spectra, based on dynamical mean field theory, in the Hubbard-I approximation, to ease experiment...

  15. Social and Environmental Impact of the Rare Earth Industries

    Directory of Open Access Journals (Sweden)

    Saleem H. Ali

    2014-02-01

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

  16. Rare Earths of Two Types Granites in Sawuer Region, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    Yuan Feng; Zhou Taofa; Tan Lugui; Fan Yu; Yue Shucang

    2005-01-01

    The geochemical characteristics of rare earth elements of A type and I type granites were studied in the Sawuer region, Xinjiang. The characteristics of two types granites are different obviously,because the A type and I type granites formed at different stage of the post-collisional period. The Sentasi intrusion and Wokensala intrusion are the I type granites formed at the late of post-collisional period, and there is extrusion translating to extension stress. The characteristics of rare earth elements show that the fractional crystallization of the I type granites is indistinct, and the sources of the I type granites come from the mantle. The Kuoyitasi intrusion and Qiaqihai intrusion are the A type granites formed at the end of post-collisional period, and there is extension stress. The characteristics of rare earth elements show that the fractional crystallization of the A type granites is distinct. The sources of the A type granites come from the mantle but interfused by the crust.

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

    Science.gov (United States)

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

    2015-11-01

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

  18. Study of amorphous semiconductors doped with rare earths (Gd and Er) and conducting polymers by EPR techniques and magnetic susceptibility; Estudo de semicondutores amorfos dopados com terras raras (Gd e Er) e de polimeros condutores atraves das tecnicas de RPE e susceptibilidade magnetica

    Energy Technology Data Exchange (ETDEWEB)

    Sercheli, Mauricio da Silva

    1999-07-01

    This thesis involves the study of amorphous semiconductors and conducting polymers, which have been characterized by EPR and magnetic susceptibility measurements, and to a lesser extent by Raman spectroscopy and RBS. The semiconductors were studied using thin films of silicon doped with rare earth metals, e.g. erbium and gadolinium, which had their magnetic properties studied. Using these studies we could determine the state of valence of the rare earths as well as their concentrations in the silicon matrix. According to our results, the valence of the rare earth metal ions is 3+, and we were able to conclude that 4f electronic shells could not be used for the calculation of the conducting band in this system. Furthermore, the analysis of the data on the magnetic susceptibility of the Er{sup 3+} ion with cubic crystalline acting field, gave us the opportunity to estimate the overall splitting of their electronic states for the first time. The conducting polymers were studied using samples of poly(3-methylthiophene) doped with ClO{sub 4}{sup -}, which show a phase transition in the range of 230 K to 130 K. The electron paramagnetic resonance also gives important information on the crystallization, doping level and the presence of polarons or bipolarons in conducting polymers. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-10-01

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

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

    Science.gov (United States)

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

    1997-10-01

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

  1. Investigations into Rare Earth Oxide Use and Behaviour

    Science.gov (United States)

    Pryce, Owen

    2010-05-01

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

  2. Study on rare earth/alkaline earth oxide-doped CeO2 solid electrolyte

    Institute of Scientific and Technical Information of China (English)

    YAN Kai; ZHEN Qiang; Song Xiwen

    2007-01-01

    Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the Sm2O3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Sm0.20Ce0.8O1.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the Arrhenius equation. Then the Sm2O3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.

  3. Structure and properties of intermetallic ternary rare earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Casper, Frederick

    2008-12-17

    The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

  4. A study on the deactivation of USY zeolites with different rare earth contents

    Energy Technology Data Exchange (ETDEWEB)

    Henriques, C.A.; Santos, J.O.J. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Polato, C.M.S.; Valle, Murta; Aguiar, E.F.S. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Quimica; Monteiro, J.L.F. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Nucleo de Catalise

    1998-06-01

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

  5. High pressure {mu}SR studies: rare earths and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Kalvius, G.M., E-mail: kalvius@ph.tum.de; Schreier, E. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ekstroem, M.; Hartmann, O. [Uppsala University, Physics Department (Sweden); Henneberger, S., E-mail: kalvius@ph.tum.de; Kratzer, A. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Waeppling, R. [Uppsala University, Physics Department (Sweden); Martin, E., E-mail: kalvius@ph.tum.de; Burghart, F.J. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ballou, R.; Deportes, J. [CNRS, Laboratoire Louis Neel (France); Niedermayer, Ch. [University of Constance, Faculty of Physics (Germany)

    2000-11-15

    After a short introduction to {mu}SR with respect to the study of magnetic properties, followed by a brief outline of the principle of the high pressure-low temperature {mu}SR spectrometer installed at the Paul Scherrer Institute, we discuss some measurements on rare earth materials employing this instrument. They are concerned with: (1) The pressure dependence of the spin turning process in ferromagnetic Gd. (2) The volume dependence of the internal magnetic field in the heavy rare earth metals Gd, Dy, and Ho in their ordered magnetic states. (3) The response of the (first order) magnetic transition in the frustrated antiferromagnets of type RMn{sub 2} (R = Y,Gd) to pressure. (4) The variation of magnetic parameters with pressure in La{sub 2}CuO{sub 4} (powder sample), the antiferromagnetic parent compound of the high T{sub C} superconductors of type La{sub 2-x}(Sr, Ba){sub x}CuO{sub 4}. In conclusion a short outlook on further developments is given.

  6. Rare earth metals in North America; Zeldzame aardmetalen in Noord-Amerika

    Energy Technology Data Exchange (ETDEWEB)

    Louzada, K.

    2012-11-15

    The uncertain supply of rare earth metals (Rare Earth Elements) from China for the high tech industry in the U.S. is a barrier for innovation and the high-tech manufacturing industry. Many rare earths are applied in permanent magnets for sustainable energy generation and for energy storage systems in for example electric cars. Also other sectors feel the pressure of shortages. The federal government in the USA and US companies use the opportunity to encourage research into recycling, reducing the use and finding alternatives for rare earths. Canada sees in the uncertain supply and dwindling reserves in the USA and elsewhere an economic opportunity. Canada can start the development of hitherto unprofitable reserves of valuable materials. Both in the USA and Canada, the number of exploration projects in the mining industry has grown significantly [Dutch] De onzekere aanvoer van zeldzame aardmetalen (Rare Earth Elements) uit China voor de hightechindustrie vormt in de VS een hindernis voor innovatie en voor de hightech maakindustrie. Met name in permanente magneten voor duurzame energieopwekking en energieopslagsystemen voor bijvoorbeeld elektrische auto's worden veel zeldzame aardmetalen verwerkt. Ook andere sectoren staan onder druk. De federale overheid en bedrijven in de VS maken van de gelegenheid gebruik om onderzoek naar de recycling, vermindering van het gebruik en alternatieven voor zeldzame aardmetalen te stimuleren. Canada ziet de onzekere aanvoer en slinkende reserves in de VS en elders als een economische kans. Het land kan tot nu toe onrendabele voorkomens van de waardevolle materialen gaan ontwikkelen. Zowel in de VS als in Canada is het aantal exploratieprojecten in de mijnbouw aanzienlijk gegroeid.

  7. Structure and spectroscopy of rare earth – Doped lead phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: wojciech.pisarski@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Żur, Lidia [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Goryczka, Tomasz [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland); Sołtys, Marta; Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland)

    2014-02-25

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}, Er{sup 3+}) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ({sup 207}Pb and {sup 31}P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO{sub 4} crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu{sup 3+} the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f{sup 6}–4f{sup 6} (Eu{sup 3+}), 4f{sup 8}–4f{sup 8} (Tb{sup 3+}), 4f{sup 9}–4f{sup 9} (Dy{sup 3+}) and 4f{sup 11}–4f{sup 11} (Er{sup 3+}) electronic transitions of trivalent rare earth ions several luminescence bands were stated.

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

    Directory of Open Access Journals (Sweden)

    Tang K.

    2013-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    宣天鹏; 张雷; 黄秋华

    2002-01-01

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

  10. The Association of China Rare Earth Industry Founded to Cope with International Trade Disputes

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>On April 8,the long-awaited Association of China Rare Earth Industry was eventually founded in Beijing.The association is composed of 155 members including Chinalco, Minmetals,Baotou Steel Group and Ganzhou Rare Earth,etc.,covering nearly all rare earth

  11. Radiation effects on rare-earth doped optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Girard, S.; Marcandella, C. [CEA Bruyeres-le-Chatel, DIF 91 (France); Ouerdane, Y.; Tortech, B.; Boukenter, A.; Meunier, J.P.; Vivona, M. [Lab. Hubert Curien, CNRS, 42 - Saint-Etienne (France); Vivona, M.; Robin, Th.; Cadier, B. [iXFiber SAS, 22 - lannion (France)

    2010-07-01

    In this paper, we reviewed our previous work concerning the responses of rare-earth (RE) doped fibers (Yb, Er and Er/Yb) to various types of radiations like gamma-rays, X-rays and protons. For all these harsh environments, the main measured macroscopic radiation-induced effect is an increase of the linear attenuation of these waveguides due to the generation of point defects in the RE-doped core and silica-based cladding. To evaluate the vulnerability of this class of optical fibers for space missions, we characterize the growth and decay kinetics of their radiation-induced attenuation (RIA) during and after irradiation for various compositions. Laboratory testing reveals that this class of optical fibers is very sensitive to radiations compared to passive (RE-free) samples. As a consequence, despite the small length used for space applications, the understanding of the radiation-induced effects in this class of optical fibers becomes necessary before their integration as part of fiber-based systems like gyroscopes or communication systems. In this paper, we more particularly discussed about the relative influence of the rare-earth ions (Er{sup 3+} and/or Yb{sup 3+}) and of the glass matrix dopants (Al, P, ... ) on the optical degradation due to radiations. This has been done by using a set of five prototype optical fibers designed by the fiber manufacturer iXFiber SAS to enlighten the role of these parameters. Additional spectroscopic tools like con-focal microscopy of luminescence are also used to detect possible changes in the spectroscopy of the rare-earth ions and their consequences on the functionality of the active optical fibers. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-02-01

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

  13. Recent Progress on Nanoscale Rare Earth Luminescent Materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results The size of nanoscale rare earth luminescent materials is often smaller than that of the excitement or emission wavelength,and it has amazing surface state density. Therefore,it shows a lot of new luminescent phenomena such as the shift of CTS,the broadening of emission peaks,the variation of fluorescent lifetimes and quantum efficiency,and the increase of quenching concentration.It is not only of academic interest but also of technological importance for advanced phosphor applications to rese...

  14. Thermoluminescence dosimetry of rare earth doped calcium aluminate phosphors

    Indian Academy of Sciences (India)

    K Madhukumar; K Rajendra Babu; K C Ajith Prasad; J James; T S Elias; V Padmanabhan; C M K Nair

    2006-04-01

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of radiation doses. Dopant concentration of 0.25 mol% cerium gives maximum TL emission. The well-defined single peak observed at 295°C can be advantageously used for high temperature dosimetry applications.

  15. Synthesis and Characterization of Rare Earth Complexes of Ferrocenylcarbonylhydrazine

    Institute of Scientific and Technical Information of China (English)

    边占喜; 董彬; 李保国

    2002-01-01

    Rare earth complexes of ferrocenylcarbonylhydrazine Ln(FH)x(ClO4)3*nH2O (where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, x=3; Ln = Er, Tm, Yb, Lu, x=4; n=2~6, FH=ferrocenylcarbonylhydrazin) were synthesized and characterized by elemental analyses, MS, IR and 1H NMR spectra. The ligand FH is bidentate, coordinating through the carbonyl oxygen and the amino nitrogen atom. The redox properties of the ligand and its complexes were investigated using cyclic voltammetric method. The solid state fluorescence spectra of Sm, Tb and Dy complexes were also studied.

  16. Resonance electronic Raman scattering in rare earth crystals

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G.M.

    1988-11-10

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

  17. Review, Intelligence and Development of Rare Earths during Biological Evolution

    Institute of Scientific and Technical Information of China (English)

    Qiu Guanming; Li Wei; Zhang Ming; Li Zhe; Yan Changhao; Li Yourong; Ding Guohui

    2004-01-01

    The relationship between organism and rare earth elements (REE) viewed from evolution was discussed.Some metal ions play key roles in biological functions, however, as the illustration in this article shows, with powerful affinities for oxygen and similar radius, REE can display equally or even more important functions in terms of its biological functions. These attractive characteristics have called more public attention and lead to many applications in agriculture, medicine fields, etc. Furthermore, the article employed the concept of entropy to discuss the dosage effect of REE on organism and the possibility whether REE can become a portion of organism during the evolution.

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

    Science.gov (United States)

    2013-11-01

    hundreds of Bq/m 3 of air; the recommended safety limits for civilian exposure are 3.5 mSv/year and 0.15 Bq/m 3 , respectively. 37 REO Mining – a...Commission for Asia and the Pacific. Atlas of Mineral Resources of the ESCAP Region, Vol. 6, Viet Nam. ST/ESCAP/831. Bangkok : UNESCAP, 1990. “US$ 35.5... Bangkok ), July 19, 2013. ProQuest (1400734925). “VINACOMIN and Japanese Firm to Exploit and Process Rare Earth in Lai Chau.” Vietnam National

  19. Electron microscopy of microwave-synthesized rare-earth chromites

    OpenAIRE

    Schmidt, Rainer; Prado-Gonjal, Jesus; Avila, David; Amador, Ulises; Moran, Emilio

    2014-01-01

    The perovskite rare-earth (RE) chromite series (RE)CrO3 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, Lu) has been synthesized in our laboratory using microwave techniques. In this work we will demonstrate how X-ray diffraction (XRD), Rietveld refinement of XRD pattern and complementary High Resolution Transmission Electron Microscopy (HRTEM) were used to confirm that the desired crystal structure had been formed. Field-emission scanning electron microscopy (FE-SEM) gave clear ...

  20. Effect of Rare Earth Elements on Quantity Growth of Ctrps

    Institute of Scientific and Technical Information of China (English)

    张自立; 常江; 等

    2002-01-01

    The effects of rare earth on the growth of rice,rape and soybean in three kinds of soils were studied with the method supposed by Economic Co-operation and Development organization(OECD),and the EC50(median growth concenrtation)values were obtained,The inhibition of RE on the growth of rice and rape in red soil and on the growth of soybeanin yellow fouvo-aquic soil is higher with stronger poison effects.Compared with other heavy metals such as Hg,Cd,Pb,As,the poison of RE on crops in weaker.