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Sample records for heavy rare-earth metals

  1. Recovering heavy rare earth metals from magnet scrap

    Science.gov (United States)

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

    2017-08-08

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

  2. Electrons and Spin Waves in Heavy Rare Earth Metals

    DEFF Research Database (Denmark)

    Mackintosh, A. R.

    1972-01-01

    this understanding on a more quantitative basis. The experimental evidence on the electronic structure of the rare earths is still rather meager but, so far as it goes, is in accord with the detailed description provided by band structure calculations. On the other hand, the experimental study of the magnon...

  3. No Giant Two-Ion Anisotropy in the Heavy-Rare-Earth Metals

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A new Bose-operator expansion of tensor operators is applied to the heavy-rare-earth metals. The Er data for the cone phase have been analyzed successfully with single-ion anisotropy and isotropic exchange interaction. The Tb data can be understood on the same basis. The previously found large two......-ion anisotropy was due to an inadequate treatment of the large single-ion anisotropy leading to an incorrect expression for the spin-wave energy....

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

    International Nuclear Information System (INIS)

    Gasgnier, M.

    1980-01-01

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

  5. Rare earth metal alloy magnets

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  6. Spin-disorder resistivity of heavy rare-earth metals from Gd to Tm: An ab-initio study

    Science.gov (United States)

    Glasbrenner, James; Belashchenko, Kirill

    2010-03-01

    Electrical resistivity of heavy rare-earth metals has a dominant contribution from thermal spin disorder scattering. In the paramagnetic state, this spin-disorder resistivity (SDR) decreases through the Gd-Tm series. Models based on the assumption of fully localized 4f states treated as S or J multiplets predict that SDR is proportional to S^2 (S is the 4f shell spin) times a quantum correction (S+1)/S or (J+1)/J. The interpretation of this correction using experimental results is ambiguous. Since the 4f bandwidth is not small compared to the multiplet splitting, it is not clear whether the 4f shells in rare-earth metals behave as if they were fully localized and have a good quantum number S or J. To address this issue, in this work we calculate the paramagnetic SDR of the rare-earth metal Gd-Tm series using a non-collinear implementation of the tight-binding linear muffin-tin orbital method. The conductance is found using the Landauer-B"uttiker approach applied to the active region of a varying size, averaging the conductance over random spin-disorder configurations and fitting its size dependence to Ohm's law. The results are compared with experiment and discussed. The sensitivity to basis set and the treatment of the 4f electrons, as well as the role of exchange enhancement in the conduction band is considered. The issue of the quantum correction is examined in light of the new results.

  7. Distribution of rare-earth (Y, La, Ce) and other heavy metals in the profiles of the podzolic soil group

    Science.gov (United States)

    Vodyanitskii, Yu. N.; Goryachkin, S. V.; Savichev, A. T.

    2011-05-01

    Along with Fe and Al, many heavy metals (Mn, Cr, Zn, Cu, and Ni) show a markedly pronounced eluvial-illuvial redistribution in the profiles of soils of the podzolic group. The intensity of the redistribution of the bulk forms of these metals is comparable with that of Fe and exceeds that of Al. Although the podzolic soils are depleted of rare-earth metals, the latter respond readily to soil podzolization. The inactive participation of Al is explained by an insignificant portion of the active reaction-capable fraction. Podzolization does not influence the profile distribution of Sr and Ba. The leaching degree of heavy metals such as Mn, Cr, Zn, Ni, and Zr is noticeably higher in the sandy podzols than in the loamy podzolic soils. Leaching of heavy metals from the podzolic horizons is of geochemical importance, whereas the depletion of metals participating in plant nutrition and biota development is of ecological importance. The leaching of heavy metals is related to the destruction of clay particles in the heavy-textured podzolic soils; the effect of the soil acidity on the leaching of heavy metals is less significant.

  8. Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants.

    Science.gov (United States)

    Shan, Xiao-Quan; Wang, Zhongwen; Wang, Weisheng; Zhang, Shuzhen; Wen, Bei

    2003-02-01

    A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L(-1) of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of soil solution fraction, F(lrss). For the soil solutions extracted with a mixture of LMWOAs the concentrations of heavy metals and rare earth elements in F(2) and F(3) were quite similar. However, the mean concentrations of Cr, Ni, Zn, Cu, Pb, Cd, La, Ce, Pr, and Nd in F(lrss) accounted for 79.9%, 91.3%, 90.8%, 60.1%, 77.5%, 75.3%, 81.2%, 77.2%, 80.3%, and 79.5%, respectively, of their concentrations in F(2). In contrast, there were no differences in the extractable metal concentrations between the three fractions while the first step of the method recommended by the European Community of Reference (BCR), where 0.1 mol L(-1) acetic acid was used as an extractant. The single correlation analysis was made between metal concentrations in the different fractions of soil solutions and their concentrations in wheat. If the first step of BCR method was used there was no good correlation between heavy metals in soil pools and that in wheat shoots and roots. When LMWAOs were used a good correlation was obtained between the concentrations of heavy metals in soil pools and that in wheat roots, which followed a general order of r(1 kD, LMWOAs) >r(0.2 microm, LMWOAs) approximately r(0.45 microm, LMWOAs). In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F(lrss) were strongly recommended to predict the bioavailability of metals in soil pools to plants.

  9. Rare earth metals for automotive exhaust catalysts

    International Nuclear Information System (INIS)

    Shinjoh, Hirohumi

    2006-01-01

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

  10. 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.

  11. Crystal fields in Sc, Y, and the heavy-rare-earth metals Tb, Dy, Ho, Er, Tm, and Lu

    International Nuclear Information System (INIS)

    Touborg, P.

    1977-01-01

    Experimental investigations of the magnetic poperties of dilute alloys of the rare-earth solutes Tb, Dy, Ho, Er, and Tm in the nonmagnetic hosts Lu, Y, and Sc have been performed. These measurements, which include and supplement earlier published results, have been analyzed and crystal-field parameters for all these 15 alloy systems deduced. The consistency of the parameters was confirmed by a variety of magnetic measurements, including neutron spectroscopy. Crystal-field parameters have also been derived for the ions in pure magnetic rare-earth metals and their alloys using the results for the dilute alloys supplemented with paramagnetic measurements up to high temperatures on the concentrated systems. Mean values and standard deviations of the higher-order crystal-field parameters for all Y and Lu alloys are B 40 /β = 6.8 +- 0.9 K, B 60 /γ = 13.6 +- 0.7 K, and B 66 /γ = (9.7 +- 1.1) B 60 /γ. These values: with the inaccuracies somewhat increased: are expected to be representative also for the magnetic rare-earth metals. For rare-earth ions in the Sc host the values B 40 /β = 9.9 +- 1.9 K, B 60 /γ = 19.8 +- 1.5 K, and B 66 /γ = (9.4 +- 0.9) B 60 /γ were deduced. B 20 /α is a host-sensitive parameter which has the average values of -102.7, -53.4, and 29.5 K for rare-earth ions in Y, Lu, and Sc, respectively. There is also evidence that this parameter varies with the solute. B 20 /α for ions in the pure magnetic rare-earth metals and their alloys shows a linear variation with c/a ratio characteristic of each ion. The results indicate a contribution from anisotropic exchange to the high-temperature paramagnetic anisotropy of approximately 20% for Tb, Dy, Ho, and Er, and approximately 10% for Tm

  12. Process for making rare earth metal chlorides

    International Nuclear Information System (INIS)

    Kruesi, P.R.

    1981-01-01

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

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

    International Nuclear Information System (INIS)

    Poirier, P.

    1979-01-01

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

  14. Environmental impacts of heavy metals, rare earth elements and natural radionuclides in marine sediment from Ras Tanura, Saudi Arabia along the Arabian Gulf.

    Science.gov (United States)

    El-Taher, Atef; Alshahri, Fatimh; Elsaman, Reda

    2018-02-01

    Ras Tanura city is one of the most important cities in Saudi Arabia because of the presence of the largest and oldest oil refinery in the Middle East which was began operations in September 1945. Also its contains gas plant and two ports. The concentration of natural radionuclides, heavy metals and rare earth elements were measured in marine sediment samples collected from Ras Tanura. The specific activities of 238 U, 226 Ra, 232 Th, 40 K and 137 Cs (Bq/kg) were measured using A hyper-pure Germanium detector (HPGe), and ranged from (20.4 ± 4.0-55.1 ± 9.9), (6.71 ± 0.7-46.1 ± 4.5), (3.51 ± 0.5-18.2 ± 1.5), (105 ± 4.4-492 ± 13) and from (0.33 ± 0.04-2.10 ± 0.4) for 238 U, 226 Ra, 232 Th, 40 K and 137 Cs respectively. Heavy metals and rare earth elements were measured using ICPE-9820 Plasma Atomic Emission Spectrometer. Also the frequency distributions for all radioactive variables in sediment samples were analyzed. Finally the radiological hazards due to natural radionuclides in marine sediment were calculated to the public and it's diagramed by Surfer program in maps. Comparing with the international recommended values, its values found to be within the international level. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Levels of rare earth elements, heavy metals and uranium in a population living in Baiyun Obo, Inner Mongolia, China: a pilot study.

    Science.gov (United States)

    Hao, Zhe; Li, Yonghua; Li, Hairong; Wei, Binggan; Liao, Xiaoyong; Liang, Tao; Yu, Jiangping

    2015-06-01

    The Baiyun Obo deposit is the world's largest rare earth elements (REE) deposit. We aimed to investigate levels of REE, heavy metals (HMs) and uranium (U) based on morning urine samples in a population in Baiyun Obo and to assess the possible influence of rare earth mining processes on human exposure. In the mining area, elevated levels were found for the sum of the concentrations of light REE (LREE) and heavy REE (HREE) with mean values at 3.453 and 1.151 μg g(-1) creatinine, which were significantly higher than those in the control area. Concentrations of HMs and U in the population increased concomitantly with increasing REE levels. The results revealed that besides REE, HMs and U were produced with REE exploitation. Gender, age, educational level, alcohol and smoking habit were major factors contributing to inter-individual variation. Males were more exposed to these metals than females. Concentrations in people in the senior age group and those with only primary education were low. Drinking and smoking were associated with the levels of LREE, Cr, Cu, Cd and Pb in morning urine. Hence this study provides basic and useful information when addressing public and environmental health challenges in the areas where REE are mined and processed. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    DEFF Research Database (Denmark)

    Williams, R. W.; Mackintosh, Allan

    1968-01-01

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

  17. IUPAC-NIST Solubility Data Series. 100. Rare Earth Metal Fluorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd–Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Mioduski, Tomasz [Institute of Nuclear Chemistry and Technology, 03195 Warszawa (Poland); Gumiński, Cezary, E-mail: cegie@chem.uw.edu.pl [Department of Chemistry, University of Warsaw, 02093 Warszawa (Poland); Zeng, Dewen, E-mail: dewen-zeng@hotmail.com [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2015-06-15

    This is the third part of the volume devoted to solubility data for the rare earth metal (REM) fluorides in water and in aqueous ternary and multicomponent systems. It covers experimental results of trivalent fluorides of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu (so-called heavy lanthanides), since no quantitative data on solubilities of TbF{sub 4} and YbF{sub 2} (the most stable compounds at these valencies) are available. The related literature has been covered through the end of 2014. Compilations of all available papers with the solubility data are introduced for each REM fluoride with a corresponding critical evaluation. Every such assessment contains a collection of all solubility results in aqueous solution, a selection of suggested solubility data, a solubility equation, and a brief discussion of the multicomponent systems. Only simple fluorides (no complexes or double salts) are treated as the input substances in this report. General features of the systems, such as nature of the equilibrium solid phases, solubility as a function of temperature, influence of ionic strength, solution pH, mixed solvent medium on the solubility, quality of the solubility results, and the solubility as a function of REM atomic number, have already been presented in Part 1 of the volume.

  18. Determination of the heavy rare earth radionuclides in melted rock

    International Nuclear Information System (INIS)

    Li Yinming; Wang Yalong; Zhang Quanshi

    1995-01-01

    There are some heavy rare earth radionuclides in the melted rocks, such as 160 Tb, 168,170 Tm, 88,91 Y, 174,177 Lu, 169 Yb, etc.. Because their contents are very low in the melted rocks and the light rare earth fission products are interfered with their determination, it is very complicated to measure them quantitatively. So a new method has been studied in which P507 resin is used to separate and purify the rare earths. Radioactive sources are prepared by the pieces of filter paper for determining chemical yield with X-fluorescence analysis, and radioactive activity is determined with the γ-spectra analysis. It is proved that this method has satisfied the demands of experiments

  19. Investigating Heavy Metal Pollution in Mining Brownfield and Its Policy Implications: A Case Study of the Bayan Obo Rare Earth Mine, Inner Mongolia, China

    Science.gov (United States)

    Pan, Yuxue; Li, Haitao

    2016-04-01

    The rapid urbanization of China and associated demand for land resources necessitates remediation, redevelopment, and reclamation of contaminated soil. Before these measures are taken, a basic investigation and inventory of heavy metal (HM) pollution levels in contaminated soil is necessary for establishing and implementing the redevelopment plan. In the present study, to identify the policy implications of inventorying and mapping HM pollution of soil in brownfields throughout China, the Bayan Obo giant rare earth element (REE)-Nb-Fe ore deposit of Baotou in Inner Mongolia, China, which is the largest REE mineral deposit in the world, was taken as a case study. Soil samples from 24 sites in Bayan Obo mining area (MA) and 76 sites in mine tailing area (TA) were collected for determining contents of soil HMs (Cr, Cd, Pb, Cu, and Zn). The results showed that the average concentrations of Cr, Cd, Pb, Cu, and Zn in both MA and TA were all higher than their corresponding background values for Inner Mongolia but lower than the Class II criteria of the National Soil Quality Standards of China (GB 15618—1995). Enrichment factor (EF) analysis of the soil samples indicated that the soil in the brownfield sites was highly enriched with Cr, Cd, Pb, Cu, and Zn compared to the corresponding background values. In MA, the EF for Cd was the highest among the studied elements, while in TA, the EF for Cr (3.45) was the highest, closely followed by the EF for Cd (3.34). The potential ecological risk index (RI) indicated a moderate potential ecological risk from the studied HMs in MA and a low potential ecological risk in TA, and the results of RI also suggested that the soil was most heavily polluted by Cd. According to the spatial distribution maps of HM, contamination hot-spots were primarily located near mining-related high-pollution plants. Based on the results, policy recommendations are proposed related to brownfield management in urban planning.

  20. Investigating Heavy Metal Pollution in Mining Brownfield and Its Policy Implications: A Case Study of the Bayan Obo Rare Earth Mine, Inner Mongolia, China.

    Science.gov (United States)

    Pan, Yuxue; Li, Haitao

    2016-04-01

    The rapid urbanization of China and associated demand for land resources necessitates remediation, redevelopment, and reclamation of contaminated soil. Before these measures are taken, a basic investigation and inventory of heavy metal (HM) pollution levels in contaminated soil is necessary for establishing and implementing the redevelopment plan. In the present study, to identify the policy implications of inventorying and mapping HM pollution of soil in brownfields throughout China, the Bayan Obo giant rare earth element (REE)-Nb-Fe ore deposit of Baotou in Inner Mongolia, China, which is the largest REE mineral deposit in the world, was taken as a case study. Soil samples from 24 sites in Bayan Obo mining area (MA) and 76 sites in mine tailing area (TA) were collected for determining contents of soil HMs (Cr, Cd, Pb, Cu, and Zn). The results showed that the average concentrations of Cr, Cd, Pb, Cu, and Zn in both MA and TA were all higher than their corresponding background values for Inner Mongolia but lower than the Class II criteria of the National Soil Quality Standards of China (GB 15618-1995). Enrichment factor (EF) analysis of the soil samples indicated that the soil in the brownfield sites was highly enriched with Cr, Cd, Pb, Cu, and Zn compared to the corresponding background values. In MA, the EF for Cd was the highest among the studied elements, while in TA, the EF for Cr (3.45) was the highest, closely followed by the EF for Cd (3.34). The potential ecological risk index (RI) indicated a moderate potential ecological risk from the studied HMs in MA and a low potential ecological risk in TA, and the results of RI also suggested that the soil was most heavily polluted by Cd. According to the spatial distribution maps of HM, contamination hot-spots were primarily located near mining-related high-pollution plants. Based on the results, policy recommendations are proposed related to brownfield management in urban planning.

  1. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Hackbarth, Liisa

    2015-11-24

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H{sub 2}O){sub 5}][B(CN){sub 4}]{sub 3}.0.5 H{sub 2}O, where LRE{sup 3+} is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3} and the [HRE(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.3 H{sub 2}O, where HRE{sup 3+} is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical

  2. Tetracyanidoborates with triply charged rare earth metal cations and their optical properties

    International Nuclear Information System (INIS)

    Hackbarth, Liisa

    2015-01-01

    The aim of this thesis is the description of the synthesis and characterization of a new group of tetracyanidoborates: tetracyanidoborates with trivalent rare earth metal cations. Their optical properties in the ultraviolet and visible range are also discussed. Common synthetic routes for tetracyanidoborates are adapted and applied to the preparation of the rare earth tetracyanidoborate hydrates. They are accessible with high yields and high purity through a reaction between the tetracyanidoboronic acid and rare earth hydroxides. It is shown that the rare earth tetracyanidoborates form isostructural groups, like the [LRE(H_2O)_5][B(CN)_4]_3.0.5 H_2O, where LRE"3"+ is La, Ce, Pr, Nd, Sm, Eu and Gd, the [HRE(H_2O)_7][B(CN)_4]_3 and the [HRE(H_2O)_8][B(CN)_4]_3.3 H_2O, where HRE"3"+ is Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. Furthermore, the coordination number 9 is noticed to be common among the light rare earth cations, whereas the minor coordination number 8 is prevalent for the heavy rare earth cations in their tetracyanidoborates. This different construction of the coordination spheres between light and heavy rare earth cations leads to different structures depending on the energetic efficiency of the structural arrangement. Generally, the rare earth tetracyanidoborate hydrates are found to crystallize in the monoclinic crystal system. Moreover, other different crystal structures are observed depending on the crystallization temperature and the type of coordinated ligands and co-crystallized solvent molecules. The tetracyanidoborate hydrates with triply charged rare earth cations are characterized comprehensively by X-ray diffraction, vibrational spectroscopy, NMR-spectroscopy as well as by thermal analysis. Furthermore, the optical properties of some dehydrated rare earth tetracyanidoborates are investigated by UV-spectroscopy and luminescence measurements. The results of the optical measurements indicate that the tetracyanidoborates with rare earth metal cations

  3. Trace determination of yttrium and some heavy rare-earths by adsorptive stripping voltammetry

    International Nuclear Information System (INIS)

    Wang, J.; Zadeii, J.M.

    1986-01-01

    The interfacial and redox behaviour of rare-earth chelates the Solochrome Violet RS are exploited for developing a sensitive adsorptive stripping procedure. Yttrium and heavy rare earths such as dysprosium, holmium and ytterbium can thus be measured at ng/ml levels and below, by controlled adsorptive accumulation of the metal chelate at the hanging mercury drop electrode, followed by voltammetric measurement of the surface species. With a 3-min preconcentration time, the detection limit ranges from 5 x 10 -10 to 1.4 x 10 -9 M. The relative standard deviation at the 7 ng/ml level ranges from 4 to 7%. A separation method is required to differentiate between the individual rare-earth metals. (author)

  4. Rare-earth metal transition metal borocarbide and nitridoborate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Niewa, Rainer; Shlyk, Larysa; Blaschkowski, Bjoern [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

    2011-07-01

    Few years after the discovery of superconductivity in high-T{sub c} cuprates, borocarbides and shortly after nitridoborates with reasonably high T{sub c}s up to about 23 K attracted considerable attention. Particularly for the rare-earth metal series with composition RNi{sub 2}[B{sub 2}C] it turned out, that several members exhibit superconductivity next to magnetic order with both T{sub c} above or below the magnetic ordering temperature. Therefore, these compounds have been regarded as ideal materials to study the interplay and coexistence of superconductivity and long range magnetic order, due to their comparably high ordering temperatures and similar magnetic and superconducting condensation energies. This review gathers information on the series RNi{sub 2}[B{sub 2}C] and isostructural compounds with different transition metals substituting Ni as well as related series like RM[BC], RM[BN], AM[BN] and R{sub 3}M{sub 2}[BN]{sub 2}N (all with R = rare-earth metal, A = alkaline-earth metal, M = transition metal) with special focus on synthesis, crystal structures and structural trends in correspondence to physical properties. (orig.)

  5. Separation of rare earth metal using micro solvent extraction system

    International Nuclear Information System (INIS)

    Nishihama, S.; Tajiri, Y.; Yoshizuka, K.

    2005-01-01

    A micro solvent extraction system for the separation of rare earth metals has been investigated. The micro flow channel was fabricated on a PMMA plate. Extraction equilibrium was quickly achieved, without any mechanical mixing. The solvent extraction results obtained for the Pr/Sm binary solutions revealed that both rare earth metals are firstly extracted together. Following, the Pr is extracted in the organic solution and Sm remains in the aqueous phase. The phase separation can be successively achieved by contriving the cross section of the flow channel

  6. Magnetism in rare-earth metals and rare-earth intermetallic compounds

    International Nuclear Information System (INIS)

    Johansson, B.; Nordstroem, L.; Eriksson, O.; Brooks, M.S.S.

    1991-01-01

    Some of out recent local spin density electronic structure calculations for a number of ferromagnetic rare-earth systems are reviewed. A simplified model of the level densities for rare-earth (R) transition metal (M) intermetallic compounds, R m M n , is used to describe in a simple way the main features of their basic electronic structure. Explicit calculations for LuFe 2 and RFe 2 (R=Gd-Yb) systems are presented, where a method to treat simultaneously the localized 4f and the conduction electron spin magnetism is introduced. Thereby it becomes possible to calculate the K RM exchange coupling constant. This method is also used to study theoretically the permanent magnet material Nd 2 Fe 14 B. The electronic structure of the anomalous ferromagnets CeFe 2 and CeCo 5 is discussed and an induced 4f itinerant magnetism is predicted. The γ-α transition in cerium metal is considered, and results from calculations including orbital polarization are presented, where a volume collapse of 10% is obtained. On one side of the transition the 4f electrons are calculated to be essentially non-bonding (localized) and on the other side they are found to contribute to the metallic bonding and this difference in behaviour gives rise to the volume collapse. Recent calculations by Wills, Eriksson and Boring for the crystal structure changes in cerium metal under high pressure are discussed. Their successful results imply an itinerant picture for the 4f electrons in α-cerium. Consequently this strongly supports the view that the γ-α phase transformation is caused by a Mott transition of the 4f electrons. (orig.)

  7. Cationic rare-earth metal SALEN complexes.

    Science.gov (United States)

    Liu, Qiancai; Meermann, Christian; Görlitzer, Hans W; Runte, Oliver; Herdtweck, Eberhardt; Sirsch, Peter; Törnroos, Karl W; Anwander, Reiner

    2008-11-28

    Complexes (Salpren(tBu,tBu))Y[N(SiHMe2)2](thf) and (SALEN(tBu,tBu))La[N(SiHMe2)2](thf) (SALEN(tBu,tBu) = Salcyc(tBu,tBu) and Salpren(tBu,tBu)) were prepared from Ln[N(SiHMe2)2]3(thf)2 and H2SALEN(tBu,tBu). The yttrium complex was characterized by X-ray crystallography revealing intrinsic solid-state structural features: the metal centre is displaced by 1.05 angstroms from the [N2O2] least squares plane of a highly bent Salpren(tBu,tBu) ligand (angle(Ph,Ph) dihedral angle of 80.4(1) degrees ) and is coordinated asymmetrically by the silylamide ligand exhibiting one significant Y---(HSi) beta-agostic interaction (Y-N1-Si1, 106.90(9) degrees; Y---Si1, 3.2317(6) angstroms). Complexes (SALEN(tBu,tBu))Ln[N(SiHMe2)2](thf)n (n = 1, Sc; n = 2, Y, La) react with ammonium tetraphenylborate to form the ion pairs [(SALEN(tBu,tBu))Ln(thf)n][BPh4]. The cationisation was proven by X-ray crystal structure analyses of [(Salpren(tBu,tBu))Sc(thf)2][B(C6H5)4].2(thf) and [(Salpren(tBu,tBu))Ln(thf)3][B(C6H5)4].4(thf) (Ln = Y, La), showing an octahedral and pentagonal-bipyramidal coordination geometry, respectively.

  8. Nuclear orientation studies of rare-earth metals

    International Nuclear Information System (INIS)

    Krane, K.S.; Morgan, G.L.; Moses, J.D.

    1981-01-01

    The angular distributions of gamma rays from 166 sup(m)Ho and 160 Tb aligned at low temperatures in, respectively, Ho metal and Tb metal have been measured. Large hyperfine splittings, expected for the rare earths, have been deduced from the temperature dependence of the gamma ray anisotropies. Both samples show a macroscopic magnetic anisotropy which is not consistent with an interpretation in terms of a randomly oriented polycrystalline structure. (orig.)

  9. Targeting heavy rare earth elements in carbonatite complexes

    Science.gov (United States)

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

    2012-04-01

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

  10. Electron states in thulium and other rare-earth metals

    International Nuclear Information System (INIS)

    Strange, P.; Fairbairn, W.M.; Lee, P.M.

    1983-01-01

    The LMTO method has been applied to calculate band structures for the heavier rare-earth metals. The calculations are relativistic. Thulium in particular has been considered, where a frozen core approximation is used, and the outer electrons are treated selfconsistently. Problems associated with the localisation and interactions of the 4f electrons are discussed. Teh comparisons between experimental data and calculated quantities are encouraging, but more data on high-purity single crystals would be helpful. (author)

  11. Vibrational spectra of double rare earth alkaline metal metaphosphates

    International Nuclear Information System (INIS)

    Madij, V.A.; Krasilov, Yu.I.; Kizel', V.A.; Denisov, Yu.V.; Chudinova, N.N.; Vinogradova, N.V.

    1978-01-01

    Joint analysis of the Raman and infrared absorption spectra, as well as X-ray structural data for binary metaphosphates, suggest a cyclic structure of the anion in RbEu(PO 3 ) 4 and a chain structure of the anions in HEu(PO 3 ) 4 and LiEu(PO 3 ) 4 . Spectroscopic criteria are proposed for distinguishing between cyclic and chain structures in binary metaphosphates of rare earth elements and alkali metals

  12. High coercivity rare earth-transition metal magnets

    International Nuclear Information System (INIS)

    Croat, J.J.

    1982-01-01

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

  13. High coercivity rare earth-transition metal magnets

    International Nuclear Information System (INIS)

    Croat, J.J.

    1982-01-01

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

  14. Rare metal and rare earth pegmatites of Western India

    International Nuclear Information System (INIS)

    Maithani, P.B.; Nagar, R.K.

    1999-01-01

    Rajasthan Mica Belt in western India is one of the three major mica-producing Proterozoic pegmatite belts of India, the others being in Bihar and Andhra Pradesh. The pegmatites of these mica belts, in general, are associated with the rare metal (RM) and rare earth element (REE)-bearing minerals like columbite-tantalite, beryl, lepidolite and other multiple oxides. RM-REE pegmatites of Gujarat are devoid of commercially workable mica. These pegmatites are geologically characterised in this paper, based on their association with granite plutons geochemistry, and RM and REE potential. In addition to RM and RE-bearing pegmatites, granites of the Umedpur area, Gujarat also show anomalous concentration (0.97 wt%) of rare metals (6431 ppm Nb, 1266 ppm Ta, 454 ppm Sn, 173 ppm W), (1098 ppm Ce 1.36% Y 2 O 3 ) rare earths, and uranium (0.40% eU 3 O 8 ). Eluvial concentrations in the soil and panned concentrate (0.04-0.28 wt%) analysed up to 7.4%Nb 2 O 5 , 836 ppm Ta, and 1.31% Y. Discrete columbite-tantalite and betafite have been identified in these concentrates in addition to other minerals like zircon, rutile, sphene and xenotime. This area with discrete RM R EE mineral phases could be significant as a non-pegmatite source for rare metal and rare earths. (author)

  15. Heavy rare earths, permanent magnets, and renewable energies: An imminent crisis

    International Nuclear Information System (INIS)

    Smith Stegen, Karen

    2015-01-01

    This article sounds the alarm that a significant build-out of efficient lighting and renewable energy technologies may be endangered by shortages of rare earths and rare earth permanent magnets. At the moment, China is the predominant supplier of both and its recent rare earth industrial policies combined with its own growing demand for rare earths have caused widespread concern. To diversify supplies, new mining—outside of China—is needed. But what many observers of the “rare earth problem” overlook is that China also dominates in (1) the processing of rare earths, particularly the less abundant heavy rare earths, and (2) the supply chains for permanent magnets. Heavy rare earths and permanent magnets are critical for many renewable energy technologies, and it will require decades to develop new non-Chinese deposits, processing capacity, and supply chains. This article clarifies several misconceptions, evaluates frequently proposed solutions, and urges policy makers outside of China to undertake measures to avert a crisis, such as greater support for research and development and for the cultivation of intellectual capital. - Highlights: • Rare earths are needed for many efficient lighting and renewable energy technologies. • The industries for rare earths and permanent magnets are dominated by China. • China's reliability is compromised, necessitating non-Chinese mining and processing. • Recycling, substitution and reducing rare earth content are long-term solutions only. • Policy makers should support development of supply chains and intellectual capital

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-05-01

    It is investigated how electron-electron correlations affect the intrinsic properties of rare-earth transition-metal magnets. Focusing on orbital moment and anisotropy, we perform model calculations for 3d-4f alloys and density-functional theory (DFT) calculations for NdCo5. On an independent-electron level, the use of a single Slater determinant with broken spin symmetry introduces Hund's rule correlations, which govern the behavior of rare-earth ions and of alloys described by the local spin density approximation (LSDA) and LSDA + U approximations to DFT. By contrast, rare-earth ions in intermetallics involve configuration interactions between two or more Slater determinants and lead to phenomena such as spin-charge distribution. Analyzing DFT as a Legendre transformation and using Bethe's crystal-field theory, we show that the corresponding density functionals are very different from familiar LSDA-type expressions and outline the effect of spin-charge separation on the magnetocrystalline anisotropy.

  18. Crystal field in rare-earth metals and intermetallic compounds

    International Nuclear Information System (INIS)

    Ray, D.K.

    1978-01-01

    Reasons for the success of the crystal-field model for the rare-earth metals and intermetallic compounds are discussed. A review of some of the available experimental results is made with emphasis on cubic intermetallic compounds. Various sources of the origin of the crystal field in these metals are discussed in the background of the recent APW picture of the conduction electrons. The importance of the non-spherical part of the muffin-tin potential on the single-ion anisotropy is stressed. (author)

  19. 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.

  20. High pressure behaviour of heavy rare earth antimonides

    International Nuclear Information System (INIS)

    Pagare, Gitanjali; Soni, Pooja; Srivastava, Vipul; Sanyal, S.P.

    2008-01-01

    We have investigated theoretically the high-pressure structural phase transition and cohesive properties of two heavy rare earth mono anyimonides (LnSb; Ln = Dy and Lu) by using two body interionic potential with necessary modifications to include the effect of Coulomb screening by the delocalized 4f electrons of the RE ion. The peculiar properties of these compounds have been interpreted in terms of the hybridization of f electrons with the conduction band. The calculated compression curves and the values of high-pressure behaviour have been discussed and compared with the experimental results. These compounds exhibits first order crystallographic phase transition from their NaCl (B 1 ) phase to CsCl (B 2 ) phase at 23.6 GPa and 25.4 GPa respectively. At phase transition the % volume collapse for both the compounds are little higher than the measured ones. The NaCl phase possesses lower energy than CsCl phase and stable at ambient pressure. The bulk moduli of LnSb compounds are obtained from the P-V curve fitted by the Birch equation of state. We also calculated the Ln-Ln distance as a function of pressure. (author)

  1. Separation process of heavy rare earth elements from xenotime ore

    International Nuclear Information System (INIS)

    Sri Sukmajaya; Tri Handini; Wahyu Rachmi Pusparini; Dwi Biyantoro

    2016-01-01

    Separation process of heavy rare earth elements from xenotime ore had been done. A 100 mesh of xenotime ore was upgrade using water, sodium silicate and oleic acid in pH 9. Mixed of slurry by air blown in room temperature along 30 minutes. The middle of slurry xenotime was be separated, then dried and so added soda caustic, potassium carbonate and ammonium dihydrogen phosphate. The mix was be homogenized then leached in furnace to 700°C temperature along 4 hours. The frits of leaching product would be leached using 1200 mL volume of water that made oxidation by HCl onto pH 4 by agitated heated in 70°C temperature. The mix was filtered, then solid settled was be dried and then to processed again in water HCl acidified leaching alike before until pH 4 with minimized HCl added least 2 mL. The solid settled filled into 1000 mL of beker glass, added HCl viscous in 300 mL volume, hydrogen peroxide and BaCl_2/Na_2SO_4/Na_2S then heated to 100°C temperature. Let in room temperature then was filtrated. The solid settled as ThSO_4/ThS, RaSO_4/RaS. The filtrate to be settled using 15g (NH_4)_2CO_3 in 100 mL volume of water while mixed until the solution reached pH 2. The solid settled was be dried, then into the filtrate added 10 mL volume of formic acid. The solid settled of filtration was be dried. The solution of filtrate to be settled using (NH_4)_2CO_3 until pH 4. The solid settled was be filtered and dried. The filtrate was be settled using oxalic acid. The analysis of standard of oxide rare earth had been done using XRF Am"2"4"1 source. Result of these process got 100 mesh xenotime upgrade those leached in 700°C along 4 hours used (NH_4)H_2PO_4 so HRE total lifted up from 4.31 to 8.16%. Resulted of HRE oxide yield was 17.76% in pH 2. HRE oxide yield in pH 4 was 38.45%, and HRE oxide yield was 6.38% as oxalic compound, so the total HRE oxide yield was 62.59%. (author)

  2. Rare earth element and rare metal inventory of central Asia

    Science.gov (United States)

    Mihalasky, Mark J.; Tucker, Robert D.; Renaud, Karine; Verstraeten, Ingrid M.

    2018-03-06

    Rare earth elements (REE), with their unique physical and chemical properties, are an essential part of modern living. REE have enabled development and manufacture of high-performance materials, processes, and electronic technologies commonly used today in computing and communications, clean energy and transportation, medical treatment and health care, glass and ceramics, aerospace and defense, and metallurgy and chemical refining. Central Asia is an emerging REE and rare metals (RM) producing region. A newly compiled inventory of REE-RM-bearing mineral occurrences and delineation of areas-of-interest indicate this region may have considerable undiscovered resources.

  3. Rare-earth-metal nitridophosphates through high-pressure metathesis

    International Nuclear Information System (INIS)

    Kloss, Simon David; Schnick, Wolfgang

    2015-01-01

    Developing a synthetic method to target an broad spectrum of unknown phases can lead to fascinating discoveries. The preparation of the first rare-earth-metal nitridophosphate LiNdP_4N_8 is reported. High-pressure solid-state metathesis between LiPN_2 and NdF_3 was employed to yield a highly crystalline product. The in situ formed LiF is believed to act both as the thermodynamic driving force and as a flux to aiding single-crystal formation in dimensions suitable for crystal structure analysis. Magnetic properties stemming from Nd"3"+ ions were measured by SQUID magnetometry. LiNdP_4N_8 serves as a model system for the exploration of rare-earth-metal nitridophosphates that may even be expanded to transition metals. High-pressure metathesis enables the systematic study of these uncharted regions of nitride-based materials with unprecedented properties. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Preparation and structure of carbonated calcium hydroxyapatite substituted with heavy rare earth ions

    International Nuclear Information System (INIS)

    Yasukawa, Akemi; Kandori, Kazuhiko; Tanaka, Hidekazu; Gotoh, Keiko

    2012-01-01

    Highlights: ► LnCaHap solid solution particles were prepared using five types of heavy rare earth ions by a precipitation method. ► The length and the crystallinity of the LnCaHap particles first increased and then decreased with increasing Ln 3+ contents. ► A series of YCaHap solid solution particles formed with Y/(Y + Ca) = 0–0.10 were investigated using various methods in detail. -- Abstract: Calcium hydroxyapatite (CaHap) particles substituted five types of heavy rare earth ions (Ln: Y 3+ , Gd 3+ , Dy 3+ , Er 3+ and Yb 3+ ) were synthesized using a precipitation method and characterized using various means. These Ln ions strongly affected the crystal phases and the structures of the products. With increasing Ln/(Ln + Ca) in the starting solution ([X Ln ]), the length and the crystallinity of the particles first increased and then decreased. The rare earth metal-calcium hydroxyapatite (LnCaHap) solid solution particles were obtained at [X Y ] ≤ 0.10 for substituting Y system and at [X Ln ] ≤ 0.01–0.03 for substituting the other Ln systems. LnPO 4 was mixed with LnCaHap at higher [X Ln ] for all Ln systems. A series of yttrium-calcium hydroxyapatite (YCaHap) solid solutions with [X Y ] = 0–0.10 were investigated using XRD, TEM, ICP-AES, IR and TG–DTA in detail.

  5. The magnetoresistivity of some rare-earth metals

    International Nuclear Information System (INIS)

    Webber, G.D.

    1978-10-01

    The thesis describes measurements of the low temperature transverse magnetoresistivities of single crystals of rare-earth metals in magnetic fields up to 8 Tesla. A general introduction to the rare-earths, their magnetic properties and a review of the basic theory and mechanism of magnetoresistivity is given. Details of the crystal structure, growth of single crystals and sample mounting method follow. The experimental equipment and measuring techniques are then described. The low temperature transverse magnetoresistivity of polycrystalline lanthanum and single crystal praseodymium for the temperature range 4.2 - 30K is measured. The separation of the spin-disorder and Fermi-surface orbital effect contributions are described and the theoretical and experimental spin-disorder values compared. Magnetoresistivity measurements for neodymium single crystals (4.2 - 30K) are compared with the magnetic properties determined from neutron diffraction studies. Results for gadolinium single crystals (4.2 - 200K) are compared for two different impurity levels and with previous work. (UK)

  6. 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....

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

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  8. Bioavailability of heavy metals, germanium and rare earth elements at Davidschacht dump-field in mine affected area of Freiberg (Saxony)

    Science.gov (United States)

    Midula, Pavol; Wiche, Oliver

    2016-04-01

    Bioavailability research presents an essential tool, in modern phytoremediation and phytomining technologies, allowing the estimation of plant available fractions of elements in soils. However, up to date, sufficient interdisciplinary knowledge on the biogeochemically impacted behavior of specific target elements, in particular Ge and REEs in mining affected soils and their uptake into strategically used plants is lacking. This presented work is focused on a correlation study between the concentrations of selected heavy metals, Ge and REEs in soils formed on the top of the dump-field of Davidschacht and the corresponding their concentrations in 12 vascular plant species. The mine-dump of Davidschacht, situated in the Freiberg (Saxony, Germany) municipality area was chosen as the study area, which has been considered to be a high contaminated enclave, due to the mining history of the region. In total 12 sampling sites with differing composition of plant species were selected. At each sampling site soil samples from a soil depth of 0 - 10 cm and samples of plant material (shoots) were taken. The soil samples were analysed for total concentration of elements, pH (H2O) and consequently analysed by 4-step sequential extraction (SE) to determine fractions of elements that are mobile (fraction 1), acid soluble (pH 5) (fraction 2), bound to organic and oxidizable matter (fraction 3) and bound to amorphic oxides (fraction 4). The plant material was decomposed by hydrofluoric acid in order to extract the elements. Concentrations of elements in soil extracts and digestion solutions were analysed by ICP-MS. For all species bioconcentration factor (BCF) was calculated of the total concentration of elements in order to investigate the bioaccumulation potential. Arsenic (As), cadmium (Cd) and lead (Pb) were chosen as the representative heavy metals. Within the REEs neodymium (Nd) and cerium (Ce) were selected as representatives for all REEs, since Nd and Ce correlated significant

  9. Preparation and structure of carbonated calcium hydroxyapatite substituted with heavy rare earth ions

    Energy Technology Data Exchange (ETDEWEB)

    Yasukawa, Akemi, E-mail: yasukawa@cc.hirosaki-u.ac.jp [School of Home Economics, Faculty of Education, Hirosaki University, 1-bunkyo, Hirosaki, Aomori 036-8560 (Japan); Kandori, Kazuhiko [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Tanaka, Hidekazu [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Gotoh, Keiko [Faculty of Human Life and Environment, Nara Women' s University, Kita-uoya-nishi, Nara 630-8506 (Japan)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer LnCaHap solid solution particles were prepared using five types of heavy rare earth ions by a precipitation method. Black-Right-Pointing-Pointer The length and the crystallinity of the LnCaHap particles first increased and then decreased with increasing Ln{sup 3+} contents. Black-Right-Pointing-Pointer A series of YCaHap solid solution particles formed with Y/(Y + Ca) = 0-0.10 were investigated using various methods in detail. -- Abstract: Calcium hydroxyapatite (CaHap) particles substituted five types of heavy rare earth ions (Ln: Y{sup 3+}, Gd{sup 3+}, Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+}) were synthesized using a precipitation method and characterized using various means. These Ln ions strongly affected the crystal phases and the structures of the products. With increasing Ln/(Ln + Ca) in the starting solution ([X{sub Ln}]), the length and the crystallinity of the particles first increased and then decreased. The rare earth metal-calcium hydroxyapatite (LnCaHap) solid solution particles were obtained at [X{sub Y}] {<=} 0.10 for substituting Y system and at [X{sub Ln}] {<=} 0.01-0.03 for substituting the other Ln systems. LnPO{sub 4} was mixed with LnCaHap at higher [X{sub Ln}] for all Ln systems. A series of yttrium-calcium hydroxyapatite (YCaHap) solid solutions with [X{sub Y}] = 0-0.10 were investigated using XRD, TEM, ICP-AES, IR and TG-DTA in detail.

  10. Syntheses and structures of new rare-earth metal tetracyanidoborates

    Energy Technology Data Exchange (ETDEWEB)

    Falk, Fanni; Hackbarth, Liisa; Koeckerling, Martin [Anorganische Festkoerperchemie, Institut fuer Chemie, Universitaet Rostock, Albert-Einstein-Str. 3a, 18059, Rostock (Germany); Herkert, Lorena; Mueller-Buschbaum, Klaus; Finze, Maik [Institut fuer Anorganische Chemie, Institut fuer nachhaltige Chemie and Katalyse mit Bor (ICB), Julius-Maximilians-Universitaet Wuerzburg, Am Hubland, 97074, Wuerzburg (Germany)

    2017-05-04

    Six new rare-earth metal tetracyanidoborates were prepared and characterized by single-crystal X-ray diffraction. Crystals of these salts contain co-crystallized solvent molecules, such as water, acetone, ethanol, or diethyl ether. In [La(EtOH){sub 3}(H{sub 2}O){sub 2}{B(CN)_4}{sub 3}] (1), [La(EtOH)(H{sub 2}O){sub 4}{B(CN)_4}{sub 3}].Et{sub 2}O (2), and [Y(EtOH)(H{sub 2}O){sub 4}{B(CN)_4}{sub 3}].EtOH (6) the tetracyanidoborate anions are all or in part bonded to the RE{sup 3+} ions, whereas in [Pr(H{sub 2}O){sub 9}][B(CN){sub 4}]{sub 3}.(CH{sub 3}){sub 2}CO (3), [Er(H{sub 2}O){sub 8}][B(CN){sub 4}]{sub 3}.(CH{sub 3}){sub 2}CO (4), and [Lu(EtOH)(H{sub 2}O){sub 7}][B(CN){sub 4}]{sub 3}.EtOH.0.5H{sub 2}O (5) the [B(CN){sub 4}]{sup -} anions are not coordinated to the central metal atoms. Only in 1, one of the three crystallographically independent [B(CN){sub 4}]{sup -} anions acts as a bridging ligand. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Heavy mineral survey for rare earths in the Northern part of Palawan

    International Nuclear Information System (INIS)

    Reyes, R.Y.; Santos, G.P.; Magsambol, W.N.; Ramos, A.F.; Petrache, C.A.; Tabora, E.U.

    1992-01-01

    A reconnaissance geochemical survey for rare earths was carried out over the northern half of Palawan with considerable success. The survey represents the first systematic geochemical exploration effort to look for indigenous rare earth resources in the Philippines. Total area covered was about 5,000 sq km. The survey entailed the systematic collection of 740 heavy mineral panned concentrate and stream sediment samples along streams and rivers. The average sampling density was about one set of sample per 2-15 sq km. A total of 218 heavy mineral samples were analyzed for lathanum, cerium, praseodymium, neodymium and yttrium. Analysis of stream sediments for rare earths was discontinued due to the high detection limit of the X-ray fluorescence spectrometer. Results of the survey clearly indicated the effectiveness of heavy mineral sampling for rare earths at the reconnaissance level of exploration. Six anomalous and well-defined areas of interest were delineated for possible rare earth mineralization. Three priority zones were further outlined from the six prospective areas for possible follow-up surveys. Mineralogical examination of heavy minerals revealed the presence of major allanite and minor monazite as the potential hosts of rare earths in the priority zone number one. Gray monazite was identified in the priority zone number two as the rare earth mineral. Minute specks and grains of gold were visibly present in some of the heavy mineral samples taken in this area. A combined mineralization of rare earths and gold in this area is a possibility. The discovery of the first gray nodular monazite in Palawan may extend the age of the oldest rocks in the Philippines to Lower Paleozoic. A separate study to establish the age of the oldest rocks in the country is likewise necessary. (auth.). 27 refs.; 6 figs.; 8 tabs

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

    Science.gov (United States)

    Hedrick, James B.

    1997-01-01

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

  13. Calculation of binary phase diagrams between the actinide elements, rare earth elements, and transition metal elements

    International Nuclear Information System (INIS)

    Selle, J.E.

    1992-01-01

    Attempts were made to apply the Kaufman method of calculating binary phase diagrams to the calculation of binary phase diagrams between the rare earths, actinides, and the refractory transition metals. Difficulties were encountered in applying the method to the rare earths and actinides, and modifications were necessary to provide accurate representation of known diagrams. To calculate the interaction parameters for rare earth-rare earth diagrams, it was necessary to use the atomic volumes for each of the phases: liquid, body-centered cubic, hexagonal close-packed, and face-centered cubic. Determination of the atomic volumes of each of these phases for each element is discussed in detail. In some cases, empirical means were necessary. Results are presented on the calculation of rare earth-rare earth, rare earth-actinide, and actinide-actinide diagrams. For rare earth-refractory transition metal diagrams and actinide-refractory transition metal diagrams, empirical means were required to develop values for the enthalpy of vaporization for rare earth elements and values for the constant (C) required when intermediate phases are present. Results of using the values determined for each element are presented

  14. High-precision analysis on annual variations of heavy metals, lead isotopes and rare earth elements in mangrove tree rings by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Yu Kefu; Kamber, Balz S.; Lawrence, Michael G.; Greig, Alan; Zhao Jianxin

    2007-01-01

    Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change

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

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

    -phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4...

  16. Local magnetism in rare-earth metals encapsulated in fullerenes

    NARCIS (Netherlands)

    De Nadai, C; Mirone, A; Dhesi, SS; Bencok, P; Brookes, NB; Marenne, [No Value; Rudolf, P; Tagmatarchis, N; Shinohara, H; Dennis, TJS; Marenne, I.; Nadaï, C. De

    Local magnetic properties of rare-earth (RE) atoms encapsulated in fullerenes have been characterized using x-ray magnetic circular dichroism and x-ray absorption spectroscopy (XAS). The orbital and spin contributions of the magnetic moment have been determined through sum rules and theoretical

  17. Crystalline and amorphous rare-earth metallic compounds

    International Nuclear Information System (INIS)

    Burzo, E.

    1975-01-01

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

  18. Studies on the adsorption behaviour of heavy rare earths with a strong cation exchanger DOWEX 50W-2X8

    International Nuclear Information System (INIS)

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

    2014-01-01

    Rare earths have been a very fascinating area of research since long due to its wide applicability's in many field including superconductors, lasers, phosphors, medical, electronics, magnet, optics etc. Separation of rare earths is a challenging task and over the years many separation schemes based on solvent extraction, ion exchange, membrane etc have been developed and deployed. In the present work, we have investigated the adsorption behavior of heavy rare earths from a crude concentrate analyzing ∼ 80% Y 2 O 3 , ∼12% Dy 2 O 3 , ∼4% Er 2 O 3 etc., with a strong cationic exchanger namely Dowex 50W-2X8 in order to separate them in pure form. To start with, Y was selected as a representative of heavy rare earths and the conditions were optimized in batch experiments and later were applied to the feed solution containing Dy, Er, Ho etc. in a column study. Effects of experimental variables such as contact time, pH, weight of resin, concentration of the feed metal, temperature, desorption agents, on adsorption of Y was studied

  19. Dependence of ultrasound attenuation in rare earth metals on ratio of grain size and wavelength

    International Nuclear Information System (INIS)

    Kanevskij, I.N.; Nisnevich, M.M.; Spasskaya, A.A.; Kaz'mina, V.I.

    1978-01-01

    Results of investigation of dependences of ultrasound attenuation coefficient α on the ratio of grain average size D and wavelength lambda are presented. The investigations were carried out on rare earth metal samples produced by arc remelting in a vacuum furnace. It is shown that the way of α dependence curves of D/lambda for each of the rare earth metal is determined only by the D. This fact permits to use ultrasound measurement for control average diameter of the rare earth metal grain

  20. 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.

  1. Production techniques for rare earth and other heavy negative ions

    International Nuclear Information System (INIS)

    McK Hyder, H.R.; Ashenfelter, J.; McGrath, R.

    1998-01-01

    Current nuclear structure studies demand a wide range of heavy negative ion beams for tandem acceleration. Some of the wanted isotopes have low natural abundances and many have low or negative electron affinities. For these, gas injection or the use of hydrides, oxides, or fluorides is required to achieve usable intensities. The chemical properties of the target materials, and of the additive gases used to form molecular ions, often have detrimental effects on ion source performance and life. These effects include insulator breakdown, ionizer poisoning, and the erosion or deposition of material on critical electrodes. Methods of controlling sputter source conditions are being studied on the Wright Nuclear Structure Laboratory ion source test bench with the object of extending source life, increasing target efficiency, and achieving consistent negative ion outputs. Results are reported for several heavy ions including tellurium, neodymium, and ytterbium. copyright 1998 American Institute of Physics

  2. Elastic, thermal and high pressure structural properties of heavy rare earth antimonides

    International Nuclear Information System (INIS)

    Soni, P.; Pagare, G.; Sanyal, S.P.

    2009-01-01

    Pressure induced structural phase transition of two heavy rare earth antimonides (RESb; RE=Ho, Er) have been studied theoretically by using an inter-ionic potential theory. This method has been found quite satisfactory in the case of pnictides of rare earth and describes the crystal properties in the framework of rigid-ion modal. The long-range Coulomb interaction, short-range repulsive interaction and van der Waals (vdW) interactions are properly incorporated in this theory. These compounds exhibit first order crystallographic phase transition from their NaCl-type structure to CsCl-type structure at 27 GPa and 33.2 GPa, respectively. The bulk moduli of RESb compounds are compared with the experimental values of elastic constants. We have also calculated the Debye temperature by incorporating the elastic constants for both the rare earth antimonides. (author)

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  4. Calculations in solvent extraction of rare earth metals

    International Nuclear Information System (INIS)

    Sadanandam, R.; Sharma, A.K.; Fonseca, M.F.; Hubli, R.C.; Suri, A.K.; Singh, D.K.

    2010-01-01

    The paper deals with calculation of number of countercurrent stages in solvent extraction of rare earths both under total reflux and partial reflux conditions to achieve a given degree of purification and recovery. The use of Fenske's equation normally used for separation by distillation is proposed to calculate the number of stages required under total reflux, replacing relative volatility by separation factor. Kremser's equations for extraction and scrubbing are used to calculate the number of stages in extraction and scrubbing modules under partial reflux conditions. McCabe-Thiele's approach is also adopted to arrive at the number of scrubbing stages. (author)

  5. Standard entropy for borides of non-transition metals, rare-earth metals and actinides

    International Nuclear Information System (INIS)

    Borovikova, M.S.

    1986-01-01

    Using as initial data the most reliable values of standard entropy for 10 compounds, the entropies for 40 compounds of non-transition metals, rare-earth metals and actinides have been evaluated by the method of comparative calculation. Taking into account the features of boride structures, two methods, i.e. additive and proportional, have been selected for the entropy calculations. For the range of borides the entropies were calculated from the linear relation of the latter to the number of boron atoms in the boride. For borides of rare-earth metals allowance has been made for magnetic contributions in conformity with the multiplicity of the corresponding ions. Insignificant differences in the electronic contributions to the entropy for borides and metals have been neglected. For dodecaborides only the additive method has been used. This is specified by the most rigid network that provides the same contribution to compound entropy. (orig.)

  6. Contribution to the theoretical study of metallic systems containing rare earths: hyperfine interactions and exchange coupling

    International Nuclear Information System (INIS)

    Troper, A.

    1978-01-01

    A theoretical study involving rare earth impurities, which were embedded in transition metals (s-p or noble), from the point of view of the hyperfine interactions is presented. A model was created to describe a d-resonance (Anderson-Moriya) acting on a s-p conduction band which was strongly perturbed by a slater-koster potential, used to describe the rare earths which were diluted in matrices of transition elements. (author)

  7. Voltage Control of Rare-Earth Magnetic Moments at the Magnetic-Insulator-Metal Interface

    Science.gov (United States)

    Leon, Alejandro O.; Cahaya, Adam B.; Bauer, Gerrit E. W.

    2018-01-01

    The large spin-orbit interaction in the lanthanides implies a strong coupling between their internal charge and spin degrees of freedom. We formulate the coupling between the voltage and the local magnetic moments of rare-earth atoms with a partially filled 4 f shell at the interface between an insulator and a metal. The rare-earth-mediated torques allow the power-efficient control of spintronic devices by electric-field-induced ferromagnetic resonance and magnetization switching.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-15

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

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

    Science.gov (United States)

    Yang, Xiuli; Zhang, Junwei; Fang, Xihui

    2014-08-30

    With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70°C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, -74μm particle size, and 100min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1-(1-x)(1/3)=A/ρr0[HCl](0.64)exp-439,8008.314Tt. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810°C, a final product of 99% pure rare earth oxides was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Rare earth germanates

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  11. Studies on up-gradation of Erbium from a heavy fraction of rare earths with EHEHPA

    International Nuclear Information System (INIS)

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

    2014-01-01

    Erbium is an important heavy rare earth element, which finds wide applications. Recently, use of Erbium oxide as structural coating material in fusion reactor has stimulated the interest in obtaining Erbium in pure form. The separation of Erbium from other rare earths such as Dy, Ho, Y, Yb, Tm etc is very difficult due to low separation factor owing to their similar chemical properties. Additionally due to very low concentration ( 2 O 3 : 1.09, Dy 2 O 3 : 58.07, Er 2 O 3 : 22.0, Ho 2 O 3 : 13.33, Yb 2 O 3 : 4.74, Tm 2 O 3 :0.67 is obtained during purification of Y by Aliquat 336 from thiocyanate medium. In the present investigation this HRE fraction is taken as the feed material for up-gradation of Er by an acidic extractant namely 2 ethyl hexyl - 2 ethyl hexyl phosphonic acid (EHEHPA)

  12. Sythesis of rare earth metal - GIC graphite intercalation compound in molten chloride system

    International Nuclear Information System (INIS)

    Ito, Masafumi; Hagiwara, Rika; Ito, Yasuhiko

    1994-01-01

    Graphite intercalation compounds of ytterbium and neodymium have been prepared by interacting graphite and metals in molten chlorides. These rare earth metals can be suspended in molten chlorides in the presence of trichlorides via disproportionation reaction RE(0) + RE(III) = 2RE(II) at lower than 300 degC. Carbides-free compounds are obtained in these systems. (author)

  13. Alaska's rare earth deposits and resource potential

    Science.gov (United States)

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

    2012-01-01

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

  14. Nuclear orientation of rare earth impurities in ferromagnetic host metals

    International Nuclear Information System (INIS)

    Keus, H.E.

    1981-01-01

    Experiments are described investigating the behaviour of the metals Nd and Lu as impurities in a ferromagnetic host metal - iron, cobalt and nickel. The systems have been studied with the aid of nuclear orientation, making use of the interactions between the atom nuclei and the electrons - the so called hyperfine interactions. (C.F.)

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

    Directory of Open Access Journals (Sweden)

    Saleh A. Alkahtani

    2016-01-01

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

  16. A study of new rare-earth metal group-13 chalcohalides. Structures, chemistry, and optical properties

    International Nuclear Information System (INIS)

    Dorhout, P.K.; Van Calcar, P.M.

    1998-01-01

    Full text: Several new quaternary compounds from the rare-earth metal group-13 chalcohalide family have been prepared from alkaline earth halide flux reactions of binary and elemental starting materials. One compound, for example, Ca 2 La 6G a 2 S 1 4 , crystallizes as needles in an hexagonal cell while another, more disordered structure, La 11 Ga 19 Cl 6 S 42 , crystallizes as monoclinic plates. The former is a condensed structure with channels that contain the alkaline earth element while the latter forms a layered structure containing rare-earth halide clusters within interlayer galleries. These compounds are new members of a family of rare-earth metal main-group chalcogenides which show promise as electroluminescent materials. Structural and spectroscopic studies of these and related compounds will be discussed

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

    International Nuclear Information System (INIS)

    Yang, Xiuli; Zhang, Junwei; Fang, Xihui

    2014-01-01

    Highlights: • Leaching kinetics of REEs has rarely been reported. • A new method, including hydrochloric acid leaching and oxalic acid precipitation, was proposed. • REEs recovery rate of 95.16% and pure rare earth oxides of 99% were obtained. • Leaching process was controlled by chemical reaction. • The kinetic equation was determined. - Abstract: With an increase in number of waste nickel-metal hydride batteries, and because of the importance of rare earth elements, the recycling of rare earth elements is becoming increasingly important. In this paper, we investigate the effects of temperature, hydrochloric acid concentration, and leaching time to optimize leaching conditions and determine leach kinetics. The results indicate that an increase in temperature, hydrochloric acid concentration, and leaching time enhance the leaching rate of rare earth elements. A maximum rare earth elements recovery of 95.16% was achieved at optimal leaching conditions of 70 °C, solid/liquid ratio of 1:10, 20% hydrochloric acid concentration, −74 μm particle size, and 100 min leaching time. The experimental data were best fitted by a chemical reaction-controlled model. The activation energy was 43.98 kJ/mol and the reaction order for hydrochloric acid concentration was 0.64. The kinetic equation for the leaching process was found to be: 1−(1−x) 1/3 =A/ρr 0 [HCl] 0.64 exp((−439,800)/(8.314T) )t. After leaching and filtration, by adding saturated oxalic solution to the filtrate, rare earth element oxalates were obtained. After removing impurities by adding ammonia, filtering, washing with dilute hydrochloric acid, and calcining at 810 °C, a final product of 99% pure rare earth oxides was obtained

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  19. Colored cool colorants based on rare earth metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Sreeram, Kalarical Janardhanan; Aby, Cheruvathoor Poulose; Nair, Balachandran Unni; Ramasami, Thirumalachari [Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020 (India)

    2008-11-15

    Colored pigments with high near infrared reflectance and not based on toxic metal ions like cadmium, lead and cobalt are being sought as cool colorants. Through appropriate doping two pigments Ce-Pr-Mo and Ce-Pr-Fe have been developed to offer a reddish brown and reddish orange color, respectively. These pigments have been characterized and found to be highly crystalline with an average size of 300 nm. A shift in band gap energy from 2.21 to 2.18 eV has been observed when Li{sub 2}CO{sub 3} was used as a mineralizer. Scanning electron microscope-energy dispersive X-ray analysis (SEM-EDAX) measurement indicate a uniform grind shape and distribution of metal ion, with over 65% reflectance in the NIR region, these pigments can well serve as cool colorants. (author)

  20. Extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kopyrin, A.A.; Berinskij, A.E.; Keskinov, V.A.

    2000-01-01

    Isotherms of extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates by solutions of tributylphosphate (TBP) and diisooctylmethylphosphonate (DIOMP) in kerosene at 298.15 Deg C and pH 1 are presented. Equations for description of interphase distribution of components of the systems considered are suggested. These equations describe distribution of components adequately in the systems of thorium nitrate (uranyl nitrate) - rare earth nitrates - (TBP, DIOMP) in the case of wide variation of phase compositions. Dependences of separation factors on composition of aqueous phase are considered [ru

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

    International Nuclear Information System (INIS)

    Cadieu, F.J.

    1990-01-01

    This report reviews work on the optimization of film synthesized rare earth transition metal permanent magnet systems. Topics include: high coercivity in Sm-Fe-Ti-V, Sm-Fe-V, and two element systems; ThMn 12 type pseudobinary SmFe 12 - X T X ; and sputter process control for the synthesis of precisely textured RE-TM magnetic films. (JL)

  2. 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....

  3. Composite nanoparticles containing rare earth metal and methods of preparation thereof

    Science.gov (United States)

    Kandapallil, Binil Itty Ipe; Krishnan, Lakshmi; Johnson, Francis

    2018-04-10

    The present invention is directed to composite nanoparticles comprising a metal, a rare earth element, and, optionally, a complexing ligand. The invention is also directed to composite nanoparticles having a core-shell structure and to processes for preparation of composite nanoparticles of the invention.

  4. The Effect of Rare-Earth Metals on Cast Steels

    Science.gov (United States)

    1954-04-01

    sullide inclusions found in two afuminum-Jriffed steefs treated with fire pounds of misch metal per ton of steef (SOOX) 15 manganese sulfides and...deoxidation treatment by ad- ditions in the monorail ladle were better than those not given the secondary deoxidation treatment. The aluminum analyses...Suliur Addition lb/ton Place BHN Area % it-lbs It-lbs Content Regular Secondary Deoxidation (0.028%Ca as CaMnSi + o.ossy.Ai) Added to 300 lb. Monorail

  5. 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....

  6. A comprehensive analysis of the content of heavy rare-earth elements and platinum in snow samples to assess the ecological hazard of air pollution in urban areas

    Science.gov (United States)

    Vinokurov, S. F.; Tarasova, N. P.; Trunova, A. N.; Sychkova, V. A.

    2017-07-01

    Snow samples from the territory of the Setun River Valley Wildlife Sanctuary are analyzed for the content of rare-earth elements, heavy metals, and other hazardous elements by the inductively coupled plasma mass-spectrometry method. The changes in the concentrations of rare-earth elements, Pt, Pd, and indicator ratios of elements in the solid fractions of snow are revealed. A trend toward a decrease in the content of several elements northeastward of the Moscow Ring Road (MRR) is established. The level of seasonal atmospheric contamination of the area under study is assessed, and a possible source is identified.

  7. Rare earth zirconium oxide buffer layers on metal substrates

    Science.gov (United States)

    Williams, Robert K.; Paranthaman, Mariappan; Chirayil, Thomas G.; Lee, Dominic F.; Goyal, Amit; Feenstra, Roeland

    2001-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0layer can be deposited using sol-gel or metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  8. Electrochemical behavior of rare earth metals and their nitrides

    International Nuclear Information System (INIS)

    Ito, Yasuhiko; Goto, Takuya

    2004-01-01

    Pyrometallurgical recycle process using molten salts is considered to be a high potential in pyro-reprocess technologies for spent nitride fuels, and it is important to understand chemical and electro-chemical behavior of nitrides and metals in molten salts. In this study, cadmium nitrates deposited on the anode Cd plate in motlen salt (LiCl-KCl) with addition of Li 3 N are examined. The cadmium nitrates deposited have various compositions corresponding to polarization potentials and then, the relationship between the deposition potential of nitride Cd and their composition is cleared. Their standard chemical potential of CdN is estimated from electrochemical measurement. And then, potential-pH 3- diagram is drawn by voltametry examination of nitride resolution behavior with using thermochemical data of nitrides. (A. Hishinuma)

  9. Rare earth sulfates

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  10. The electrodeposition and rare earths reduction in the molten salt actinides recovery systems using liquid metal

    International Nuclear Information System (INIS)

    Shim, J-B.; Lee, J-H.; Kwon, S-W.; Ahn, B-G.; Woo, M-S.; Lee, B-J.; Kim, E-H.; Park, H-S.; Yoo, J-H.

    2005-01-01

    A pyrochemical partitioning system uses liquid metals such as cadmium and bismuth in order to recover the actinide metals from a molten salt mixture containing rare earth fission product metals. The liquid metals play roles as a cathode in the electrowinning or an extracting phase in the reductive extraction operation. The product resulting from the above operations is metal-cadmium or-bismuth alloy, which should contain the rare earth element amounts as low as possible for a transmutation purpose. In this study, the electrodeposition behaviours of uranium and lanthanide elements such as La, Ce and Nd were investigated for solid molybdenum and liquid cadmium electrodes in a molten LiCl-KCl eutectic salt. Electrochemical methods used are a cyclic voltammetry (CV) and a chronopotentiometry for monitoring the salt phase and recovering the metals, respectively. The CV graphs for monitoring the oxidizing agent CdCl 2 in the salt phase were obtained. These show a time dependently disappearance of the oxidizing agent corresponding to the formation of UCl 3 by inserting the uranium metal into the salt. Also, a sequential oxidation technique which is added at a controlled amount of the oxidizing agents into the salt phase was applied. It was found that this method is feasible for the selective reduction of the rare earths content in liquid metal alloys. (author)

  11. Study on Yen Phu rare earth ore concentrate treatment technology and separation of major heavy rare earth elements by solvent extraction method

    International Nuclear Information System (INIS)

    Le Ba Thuan; Pham Quang Trung; Vu Lap Lai

    2003-01-01

    PC88A and Aliquat 336 systems have been optimized using the computer simulation program. The solution containing > 80% pure Y 2 O 3 after upgrading by PC88A (18 extraction, 18 scrubbing and 10 stripping stages) is purified further by another cycle of SX (24 extraction, 10 scrubbing and 10 stripping stages) with 25% Aliquat 336 in kerosene in presence of 1.0 M NH 4 SCN and 2.0 M NH 4 Cl. The impurities of Ho, Er, and another heavy elements are extracted leaving >99.9% pure Y 2 O 3 in the aqueous phase. The yield of the process is > 85%. 4. Separation and purification of europium: The isolation and purification of europium consists of following steps: isolation of Eu by reduction on zinc column and precipitation in the form EuSO 4 by H 2 SO 4 under CO 2 atmosphere; first purification by conversion of EuSO 4 to EuCl 3 , reduction and precipitation in the form EuSO 4 ; and second purification by reduction on zinc column and precipitation of other rare earth elements in the form RE(OH) 3 by NH 4 Cl-NH 4 OH buffer of pH = 10 under atmosphere N 2 . Eu 2 O 3 of 99.9% purity has been recovered with overall yield. 5. Separation and purification of gadolinium: The middle subgroup after Eu removing is subject to Gd recovery by SX with PC88A. The SX parameters for Gd separation had been optimized by computer program. The separation process consists of 12 extraction, 12 scrubbing and 6 stripping stages. The acidity of scrubbing solution is 1.0.M HCl. The purity and yield of the Gd separation process were > 98% and >85% respectively. The obtained Gd 2 O 3 was purified by Eu removing using zinc column and H 2 SO 4 . The final purity of the Gd 2 O 3 was reached value 99%. 6. Overall schema for individual separation of some rare earth elements of high purity from Yenphu rare earth ore concentrate: Based on the above obtained results, overall schema for individual separation of some rare earth elements (Y, Gd, Eu and Sm) of high purity from Yenphu rare earth ore concentrate has been

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (paper)

  13. Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd doped ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    P. Logamani

    2017-06-01

    Full Text Available Presence of harmful organic pollutants in wastewater effluents causes serious environmental problems and therefore purification of this contaminated water by a cost effective treatment method is one of the most important issue which is in urgent need of scientific research. One such promising treatment technique uses semiconductor photocatalyst for the reduction of recalcitrant pollutants in water. In the present work, rare earth metals (Nd and Gd doped ZnO nanostructured photocatalyst have been synthesized by wet chemical method. The prepared samples were characterized by X-ray diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM and energy dispersive X-ray spectroscopy (EDS. The XRD results showed that the prepared samples were well crystalline with hexagonal Wurtzite structure. The results of EDS revealed that rare earth elements were doped into ZnO structure. The effect of rare earth dopant on morphology and photocatalytic degradation properties of the prepared samples were studied and discussed. The results revealed that the rare earth metal doped ZnO samples showed enhanced visible light photocatalytic activity for the degradation of methylene blue dye than pure nano ZnO photocatalyst.

  14. Investor's and procurement guide South Africa. Pt. 1. Heavy minerals, rare earth elements, antimony

    International Nuclear Information System (INIS)

    Graupner, Torsten; Schwarz-Schampera, Ulrich; Hammond, Napoleon Q.; Opperman, Rehan; Long'a Tongu, Elisa; Kenan, Abdul O.; Nondula, Unathi; Tsanwani, Matamba

    2014-01-01

    This is the first part of the ''Investor's and Procurement Guide South Africa'', a handbook for investing and doing business in South Africa's mineral industry. It is anticipated that this publication will aid potential investors into considering South Africa as an investment destination, not only for raw materials, but also for related industries. This manual supplements the many publications available on the economic geology and mineral wealth in South Africa and has been designed to guide prospective and current investors, suppliers and mine equipment exporters through the process of doing business in Africa's biggest and dynamic economy. As well as detailing the mineral raw materials heavy minerals, rare-earth metals and antimony, the handbook provides a general introduction to South Africa and its infrastructure, the economical, political and judicial frame of the South African mining industry and an overview of the economic geology. South Africa has a long and complex geological history which dates back in excess of 3.6 billion years. The country has a vast mineral wealth, undoubtedly due to the fact that a significant proportion of the Archaean and younger rocks have been preserved. The mining of the enormous Witwatersrand gold deposits, commencing in 1886, has led to the establishment of South Africa's well-developed infrastructure and to the sustained growth of an industrial and service sector in the country. With the world's largest resources of PGMs, gold, chromite, vanadium and manganese and significant resources of iron, coal and numerous other minerals and metals, the minerals industry will continue to play a pivotal role in the growth of South Africa's economy in the foreseeable future. South Africa is one of the top destinations in Africa for foreign direct investments. South African headquartered companies have been major investors into foreign direct investments on the African continent in the past decade. Investing in South African companies

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  16. Rare earth metals-primary resources and prospects of processing secondary resources in India

    International Nuclear Information System (INIS)

    Pandey, B.D.

    2015-01-01

    The importance of Rare earth metals (REMs) in modern technological applications is associated with their spectroscopic and magnetic properties. The occurrence of rare earths in mixed form is commonly reported and their separation to the individual metal is a challenging task because of the similar chemical properties. The economical processing of the primary ores of rare earths is limited to a few countries and their supply at the international level is currently dominated by China. Hence assessing the present scenario of the primary resources of rare earths vis-à-vis their applications and demand is crucial at this stage, besides looking at the alternate resources to ensure availability of REMs; such aspects are covered in the manuscript. In view of the environmental concerns in the processing of ores such as monazite, xenotime, bastnasite, etc, and increasing demand of REMs, corresponding increase in demand of the raw materials has been recorded. It is therefore, necessary to utilize the end-of the-life rare earth containing materials as a rich resource by developing an appropriate recycling technology, which is emerging as a high priority area. To recover the REMs, major secondary resources such as electronic wastes, industrial wastes, spent catalysts and magnets, and phosphors powder, etc, have been considered for now. This will not only open the prospects of utilizing the wastes containing REMs, but will also limit the imports while lowering the production cost and decreasing the load on the primary reserves. The paper also examines the efficient recycling methods to recover a fairly good amount of rare earths which are relevant to India in view of the limited exploitation of the ores. Recovery of REMs from secondary resources using mechanical treatment followed by hydrometallurgical methods is prevalent and the same is reviewed in some detail. The recent R and D work pursued at CSIR-NML to extract (leaching and metal separation using some phosphatic reagents

  17. Threefold symmetric magnetic two-ion coupling in hcp rare-earth metals

    International Nuclear Information System (INIS)

    Jensen, J.

    1997-01-01

    The heavy rare earths crystallize in the hcp structure. Most of magnetic couplings between two ions in these metals are independent of the two different orientations of the hexagonal layers. However, trigonal anisotropy terms may occur, reflecting that c-axis is only threefold axis. In the presence of a trigonal coupling the symmetry is reduced, and the double-zone representation in the c-direction ceases to be valid. The strong interaction between the transverse optical phonons and the acoustic spin waves propagating in the c-direction of Yb detected more than twenty years ago, was the first example of a trigonal coupling found in these systems. A few years ago a careful neutron-diffraction study of the c-axis modulated magnetic structures in Er showed the presence of higher harmonics at positions along the c-axis translated by odd multiple of 2φ/c. This indicates distortions of the structures due to trigonal couplings, and the same characteristic phenomenon has now been also observed in Ho. Additionally, mean field calculations show that a trigonal coupling in Ho is required, in order to explain the increase in the commensurable effects observed for the 8 and 10 layered periodic structures, when a field is applied along the c-axis. (author)

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system

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

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan; Kubota, Fukiko; Baba, Yuzo [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Kamiya, Noriho [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Goto, Masahiro, E-mail: m-goto@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2013-06-15

    Highlights: • Recycling of rare earth metals from fluorescent lamps was conducted by ionic liquid-mediated extraction. • Acid leaching from a waste phosphor powder was carried out using sulfuric and nitric acids. • An ionic liquid was used as extracting solvent for the rare earth metals. • Selective extraction of rare earth metals from leach solutions was attained. •The extracting ionic liquid phase was recyclable in the recovery process. -- Abstract: The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid–liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

  20. 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.

  1. 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.

  2. Cation exchange separation of 16 rare earth metals by microscale high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Ishii, D.; Hirose, A.; Iwasaki, Y.

    1978-01-01

    The separation of rare earth metals has been studied with a microcolumn of 0.5 mm i.d. and 75 mm length, packed with TSK LS-212 high-performance cation exchange resin. A micro-feeder (Model MF-2, from Azumadenki Kogyo) was used to drive carrier and sample solutions through the ion exchange column and detection cell. By combining a 250 μl syringe and a 0.5 mm i.d. sampling tube the micro-feeder, 0.1-1.0 μl rare earth metals were separated within 38 min, using only 304 μl of 0.4M α-hydroxy-isobutyric acid solution adjusted to pH 3.1-6.0 with ammonia solution as gradient carrier solution. The gradient elution was successfully performed by applying a new technique developed for microscale liquid chromatography. (author)

  3. μSR-studies of magnetic properties of metallic rare earth compounds

    International Nuclear Information System (INIS)

    Asch, L.; Kalvius, G.M.; Chappert, J.; Yaouanc, A.; Hartmann, O.; Karlsson, E.; Wappling, R.

    1984-01-01

    Positive muons can probe the magnitude and the time dependence of the magnetic field at interstitial sites in condensed matter. Thus the relatively new techniques of muons spin rotation and muon spin relaxation have become unique tools for studying magnetism. After a brief introduction into the experimental method we then discuss measurements on the elemental rare earth metals and on intermetallic compounds, in particular on the cubic Laves phases REAl 2

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

    Science.gov (United States)

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

    2013-12-01

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

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

    International Nuclear Information System (INIS)

    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 5 (Fe,T) 17 type crystalline phases; ThMn 12 type pseudobinary SmFe 12-x T x (0≤x≤1.5); and sputter process control for the synthesis of precisely textured rare earth-transition metal magnetic films

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

    Science.gov (United States)

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

    2013-06-15

    The recycling of rare earth metals from phosphor powders in waste fluorescent lamps by solvent extraction using ionic liquids was studied. Acid leaching of rare earth metals from the waste phosphor powder was examined first. Yttrium (Y) and europium (Eu) dissolved readily in the acid solution; however, the leaching of other rare earth metals required substantial energy input. Ionization of target rare earth metals from the waste phosphor powders into the leach solution was critical for their successful recovery. As a high temperature was required for the complete leaching of all rare earth metals, ionic liquids, for which vapor pressure is negligible, were used as an alternative extracting phase to the conventional organic diluent. An extractant, N, N-dioctyldiglycol amic acid (DODGAA), which was recently developed, showed a high affinity for rare earth metal ions in liquid-liquid extraction although a conventional commercial phosphonic extractant did not. An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system. Copyright © 2013 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

    Szpunar, B.; Lindgaard, P.A.

    1976-11-01

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

  8. Rare earths

    Energy Technology Data Exchange (ETDEWEB)

    Cranstone, D A

    1979-01-01

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

  9. Interaction of copper metallization with rare-earth metals and silicides

    International Nuclear Information System (INIS)

    Molnar, G. L.; Peto, G.; Zsoldos, E.; Horvath, Z. E.

    2001-01-01

    Solid-phase reactions of copper films with underlying gadolinium, erbium, and erbium - silicide layers on Si(100) substrates were investigated. For the phase analysis, x-ray diffraction and cross-sectional transmission electron microscopy were used. In the case of Cu/Gd/Si(100), an orthorhombic GdSi 2 formed, and, at higher temperatures, copper aggregated into islands. Annealed Cu/Er/Si(100) samples resulted in a hexagonal Er 5 Si 3 phase. In the Cu/ErSi 2-x /Si system, the copper catalyzes the transformation of the highly oriented hexagonal ErSi 2-x phase into hexagonal Er 5 Si 3 . Diverse phase developments of the samples with Gd and Er are based on reactivity differences of the two rare-earth metals. [copyright] 2001 American Institute of Physics

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

    International Nuclear Information System (INIS)

    Jia Youhua; Zhong Biao; Yin Jianping

    2009-01-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb 3+ -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. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Hydrometallurgical separation of rare earth elements, cobalt and nickel from spent nickel-metal-hydride batteries

    Science.gov (United States)

    Rodrigues, Luiz Eduardo Oliveira Carmo; Mansur, Marcelo Borges

    The separation of rare earth elements, cobalt and nickel from NiMH battery residues is evaluated in this paper. Analysis of the internal content of the NiMH batteries shows that nickel is the main metal present in the residue (around 50% in weight), as well as potassium (2.2-10.9%), cobalt (5.1-5.5%), rare earth elements (15.3-29.0%) and cadmium (2.8%). The presence of cadmium reveals that some Ni-Cd batteries are possibly labeled as NiMH ones. The leaching of nickel and cobalt from the NiMH battery powder with sulfuric acid is efficient; operating variables temperature and concentration of H 2O 2 has no significant effect for the conditions studied. A mixture of rare earth elements is separated by precipitation with NaOH. Finally, solvent extraction with D2EHPA (di-2-ethylhexyl phosphoric acid) followed by Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) can separate cadmium, cobalt and nickel from the leach liquor. The effect of the main operating variables of both leaching and solvent extraction steps are discussed aiming to maximize metal separation for recycling purposes.

  12. Materials flow analysis of neodymium, status of rare earth metal in the Republic of Korea.

    Science.gov (United States)

    Swain, Basudev; Kang, Leeseung; Mishra, Chinmayee; Ahn, JoongWoo; Hong, Hyun Seon

    2015-11-01

    Materials flow analysis of neodymium, status of rare earth elements (REEs) in the Republic of Korea has been investigated. Information from various resources like the Korean Ministry of Environment, Korea international trade association, United Nations Commodity Trade Statistics Database and from individual industry were collected and analyzed for materials flow analysis of neodymium. Demand of neodymium in the Republic of Korea for the year 2010 was 409.5 tons out of which the majority of neodymium, i.e., 68.41% was consumed by domestic electronics industry followed by medical appliances manufacturing (13.36%). The Republic Korea is one of the biggest consumer and leading exporter of these industrial products, absolutely depends on import of neodymium, as the country is lacking natural resources. The Republic of Korea has imported 325.9 tons of neodymium permanent magnet and 79.5 tons of neodymium containing equipment parts mainly for electronics, medical appliances, and heavy/light vehicles manufacturing industry. Out of which 95.4 tons of neodymium permanent magnet get exported as an intermediate product and 140.6 tons of neodymium in the form of consumable products get exported. Worldwide the neodymium is at the high end of supply chain critical metal because of increasing demand, scarcity and irreplaceable for technological application. To bring back the neodymium to supply stream the recycling of end of life neodymium-bearing waste can be a feasible option. Out of total domestic consumption, only 21.9 tons of neodymium have been collected and subsequently recycled. From material flow analysis, the requirement for an efficient recycling system and element-wise material flow management for these REEs in the Republic of Korea were realized and recommended. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Geology and rare earth (RE) metals in air Gegas area, South Bangka

    International Nuclear Information System (INIS)

    Bambang Soetopo

    2013-01-01

    Rare Earth (RE) is a valuable commodity both for industry and for the Nuclear Power Plant (NPP). In RE chemical bonds present in the phosphate (P) are the mineral monazite, xenotime, zircon minerals associated with cassiterite, magnetite, ilmenite, rutile, anatase, apatite, quartz and feldspar sand deposits are found in alluvial river or beach placer. RE deposits in monazite, zircon, xenotime in the Air Gegas of South Bangka area is an alluvial river that has the ease of exploration and mining. Geologically, monazite, xenotime and zircon minerals are from Klabat Granite aged Jurassic. The used method are the observation of geology, radioactivity measurement, sampling, laboratory analysis (microscopic and XRF). Results showed that the geology of the area Air Gegas of Tanjung Genting Formation consists of sandstone, clay (Early Triassic), Klabat Granite (Late Jurassic-Early Triassic) and Alluvial sediments (Quaternary). Alluvial monazite containing 0.071 to 3.574%, zircon from 0.172 to 10.376%, xenotime from 0.15 to 3.023% of the weight of MB from 10.73 to 168.072 grams. The presence of rare earth (RE) metals is derived from the mineral monazite, xenotime, zircon that was derived from granitic rocks of Klabat. Rare earth (RE) distributed in the eastern part of the study area which occupies the valley of the river. (author)

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

    OpenAIRE

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  16. Radiation damage produced by swift heavy ions in rare earth phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Romanenko, Anton

    2017-02-13

    This work is devoted to the study of radiation damage produced by swift heavy ions in rare earth phosphates, materials that are considered as perspective for radioactive waste storage. Single crystals of rare earth phosphates were exposed to 2.1 GeV gold (Au) and 1.5 GeV xenon (Xe) ions of and analyzed mainly by Raman spectroscopy. All phosphates were found almost completely amorphous after the irradiation by 2.1 GeV Au ions at a fluence of 1 x 10{sup 13} ions/cm{sup 2}. Radiation-induced changes in the Raman spectra include the intensity decrease of all Raman bands accompanied by the appearance of broad humps and a reduction of the pronounced luminescence present in virgin samples. Analyzing the Raman peak intensities as a function of irradiation fluence allowed the calculation of the track radii for 2.1 GeV Au ions in several rare earth phosphates, which appear to be about 5.0 nm for all studied samples. Series of samples were studied to search for a trend of the track radius depending on the rare earth element (REE) cation. Among the monoclinic phosphates both Raman and small-angle X-ray scattering (SAXS) suggest no significant change of the track radius with increasing REE mass. In contrast, within the tetragonal phosphates Raman spectroscopy data suggests a possible slight decreasing trend of the track radius with the increase of REE atomic number. That finding, however, requires further investigation due to the low reliability of the qualitative Raman analysis. Detailed analysis of Raman spectra in HoPO{sub 4} showed the increase of peak width at the initial stage of the irradiation and subsequent decrease to a steady value at higher fluences. This observation suggested the existence of a defect halo around the amorphous tracks in HoPO{sub 4}. Raman peaks were found to initially shift to lower wavenumbers with reversing this trend at the fluence of 5 x 10{sup 11} for NdPO{sub 4} and 1 x 10{sup 12} ions/cm{sup 2} for HoPO{sub 4}. At the next fluence steps

  17. Radiation damage produced by swift heavy ions in rare earth phosphates

    International Nuclear Information System (INIS)

    Romanenko, Anton

    2017-01-01

    This work is devoted to the study of radiation damage produced by swift heavy ions in rare earth phosphates, materials that are considered as perspective for radioactive waste storage. Single crystals of rare earth phosphates were exposed to 2.1 GeV gold (Au) and 1.5 GeV xenon (Xe) ions of and analyzed mainly by Raman spectroscopy. All phosphates were found almost completely amorphous after the irradiation by 2.1 GeV Au ions at a fluence of 1 x 10 13 ions/cm 2 . Radiation-induced changes in the Raman spectra include the intensity decrease of all Raman bands accompanied by the appearance of broad humps and a reduction of the pronounced luminescence present in virgin samples. Analyzing the Raman peak intensities as a function of irradiation fluence allowed the calculation of the track radii for 2.1 GeV Au ions in several rare earth phosphates, which appear to be about 5.0 nm for all studied samples. Series of samples were studied to search for a trend of the track radius depending on the rare earth element (REE) cation. Among the monoclinic phosphates both Raman and small-angle X-ray scattering (SAXS) suggest no significant change of the track radius with increasing REE mass. In contrast, within the tetragonal phosphates Raman spectroscopy data suggests a possible slight decreasing trend of the track radius with the increase of REE atomic number. That finding, however, requires further investigation due to the low reliability of the qualitative Raman analysis. Detailed analysis of Raman spectra in HoPO 4 showed the increase of peak width at the initial stage of the irradiation and subsequent decrease to a steady value at higher fluences. This observation suggested the existence of a defect halo around the amorphous tracks in HoPO 4 . Raman peaks were found to initially shift to lower wavenumbers with reversing this trend at the fluence of 5 x 10 11 for NdPO 4 and 1 x 10 12 ions/cm 2 for HoPO 4 . At the next fluence steps peaks moved in the other direction, passed

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

    Science.gov (United States)

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

    2016-05-01

    Nickel-metal hydride batteries (Ni-MH) contain not only the base metals, but valuable rare earth metals (REMs) viz. La, Sm, Nd, Pr and Ce as well. In view of the importance of resource recycling and assured supply of the contained metals in such wastes, the present study has focussed on the leaching of the rare earth metals from the spent Ni-MH batteries. The conditions for the leaching of REMs from the spent batteries were optimized as: 2M H2SO4, 348K temperature and 120min of time at a pulp density (PD) of 100g/L. Under this condition, the leaching of 98.1% Nd, 98.4% Sm, 95.5% Pr and 89.4% Ce was achieved. Besides the rare earth metals, more than 90% of base metals (Ni, Co, Mn and Zn) were also leached out in this condition. Kinetic data for the dissolution of all the rare earth metals showed the best fit to the chemical control shrinking core model. The leaching of metals followed the mechanism involving the chemical reaction proceeding on the surface of particles by the lixiviant, which was corroborated by the XRD phase analysis and SEM-EDS studies. The activation energy of 7.6, 6.3, 11.3 and 13.5kJ/mol was acquired for the leaching of neodymium, samarium, praseodymium and cerium, respectively in the temperature range 305-348K. From the leach liquor, the mixed rare earth metals were precipitated at pH∼1.8 and the precipitated REMs was analyzed by XRD and SEM studies to determine the phases and the morphological features. Copyright © 2015. Published by Elsevier Ltd.

  19. Melting temperature and structural transformation of some rare-earth metals

    International Nuclear Information System (INIS)

    Vu Van Hung; Hoang Van Tich; Dang Thanh Hai

    2009-01-01

    the pressure dependence of the melting temperatures of rare-earth metals is studied using the equation of states derived from the statistical moment (SMM). SMM studies were carried out order to calculate the Helmholtz free energy of hcp, bcc Dy and fcc, bcc Ce metals at a wide range of temperatures. the stable phase of Dy and Ce metals can be determined by examining the Helmholtz free energy at a given temperature, i, e. the phase that gives the lowest free energy will be stable. For example, we found that at T lower than 1750 K the hcp Dy metal is stable. At T higher than 1750 K the bcc Dy metal is also stable. Thus 1750 K marks the phase transition temperature of Dy metal. These findings are in agreement with previous experiments. (author)

  20. Rare earths

    International Nuclear Information System (INIS)

    1984-01-01

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

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2016-10-01

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

  6. Magnetic properties of 3d-transition metal and rare earth fluoride glasses

    International Nuclear Information System (INIS)

    Renard, J.P.; Dupas, C.; Velu, E.; Jacobini, C.; Fonteneau, G.; Lucas, J.

    1981-01-01

    The ac susceptibility of fluoride glasses in the ternary systems PbF 2 -MnF 2 -FeF 3 , ThF 4 -BaF 2 -MnF 2 , ZnF 2 -BaF 2 -RF 3 (R = Dy-Ho) has been studied down to 0.3 K. The susceptibility of rare earth glasses exhibits a broad maximum strongly dependent on the measuring frequency ν while a spin glass transition with a sharp susceptibility cusp nearly independent on ν is observed in 3d-transition metal glasses. Magnetic after effects are observed below the spin freezing temperature. (orig.)

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

    Science.gov (United States)

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

    2015-05-04

    Highly selective, narcissistic self-sorting can be achieved in the formation of self-assembled cages of rare earth metals with multianionic salicylhydrazone ligands. The assembly process is highly sensitive to the length of the ligand and the coordination geometry. Most surprisingly, high-fidelity sorting is possible between ligands of identical coordination angle and geometry, differing only in a single functional group on the ligand core, which is not involved in the coordination. Supramolecular effects allow discrimination between pendant functions as similar as carbonyl or methylene groups in a complex assembly process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Marine Phosphorites as Potential Resources for Heavy Rare Earth Elements and Yttrium

    Directory of Open Access Journals (Sweden)

    James R. Hein

    2016-08-01

    Full Text Available Marine phosphorites are known to concentrate rare earth elements and yttrium (REY during early diagenetic formation. Much of the REY data available are decades old and incomplete, and there has not been a systematic study of REY distributions in marine phosphorite deposits that formed over a range of oceanic environments. Consequently, we initiated this study to determine if marine phosphorite deposits found in the global ocean host REY concentrations of high enough grade to be of economic interest. This paper addresses continental-margin (CM and open-ocean seamount phosphorites. All 75 samples analyzed are composed predominantly of carbonate fluorapatite and minor detrital and authigenic minerals. CM phosphorites have low total REY contents (mean 161 ppm and high heavy REY (HREY complements (mean 49%, while seamount phosphorites have 4–6 times higher individual REY contents (except for Ce, which is subequal; mean ΣREY 727 ppm, and very high HREY complements (mean 60%. The predominant causes of higher concentrations and larger HREY complements in seamount phosphorites compared to CM phosphorites are age, changes in seawater REY concentrations over time, water depth of formation, changes in pH and complexing ligands, and differences in organic carbon content in the depositional environments. Potential ore deposits with high HREY complements, like the marine phosphorites analyzed here, could help supply the HREY needed for high-tech and green-tech applications without creating an oversupply of the LREY.

  9. Localized-itinerant magnetism: a simple model with applications to intermetallic of heavy rare-earths

    International Nuclear Information System (INIS)

    Ranke Perlingueiro, P.J. von.

    1986-01-01

    We have investigated various magnetic quantities of a system consisting of conduction electrons coupled to localized spins. In obtaining the magnetic state equations (which relate the ionic and electronic magnetisations to temperature and the model parameters) we have adopted the molecular field approximation. This simple model is of interest to the magnetism of the heavy rare earth intermettallics. For these systems the localized spin is that of the 4f shell; it is described by the parameters g (the Lande's factor) and J (the total angular momentum of the 4f electrons in the ground state). We derive an analytical linear relation between the critical temperature and The Gennes Factors J(J+1)(g-1) which is experimentally observed for RAl 2 . A fitting between the experimental points and the theoretical prediction gives for the exchange parameter the value J o = 48.6 meV. We have also performed a parametric study of the model, using a rectangular energy density of states. The results are shown on tables and diagrams. (author) [pt

  10. Structurally triggered metal-insulator transition in rare-earth nickelates.

    Science.gov (United States)

    Mercy, Alain; Bieder, Jordan; Íñiguez, Jorge; Ghosez, Philippe

    2017-11-22

    Rare-earth nickelates form an intriguing series of correlated perovskite oxides. Apart from LaNiO 3 , they exhibit on cooling a sharp metal-insulator electronic phase transition, a concurrent structural phase transition, and a magnetic phase transition toward an unusual antiferromagnetic spin order. Appealing for various applications, full exploitation of these compounds is still hampered by the lack of global understanding of the interplay between their electronic, structural, and magnetic properties. Here we show from first-principles calculations that the metal-insulator transition of nickelates arises from the softening of an oxygen-breathing distortion, structurally triggered by oxygen-octahedra rotation motions. The origin of such a rare triggered mechanism is traced back in their electronic and magnetic properties, providing a united picture. We further develop a Landau model accounting for the metal-insulator transition evolution in terms of the rare-earth cations and rationalizing how to tune this transition by acting on oxygen rotation motions.

  11. Effects of Rare Earth Metal Addition on Wear Resistance of Chromium-Molybdenum Cast Steel

    Directory of Open Access Journals (Sweden)

    Kasinska J.

    2017-09-01

    Full Text Available This paper discusses changes in the microstructure and abrasive wear resistance of G17CrMo5-5 cast steel modified with rare earth metals (REM. The changes were assessed using scanning microscopy. The wear response was determined in the Miller test to ASTM G75. Abrasion tests were supplemented with the surface profile measurements of non-modified and modified cast steel using a Talysurf CCI optical profilometer. It was demonstrated that the modification substantially affected the microstructure of the alloy, leading to grain size reduction and changed morphology of non-metallic inclusions. The observed changes in the microstructure resulted in a three times higher impact strength (from 33 to 99 kJ/cm2 and more than two times higher resistance to cracking (from 116 to 250 MPa. The following surface parameters were computed: Sa: Arithmetic mean deviation of the surface, Sq: Root-mean-square deviation of the surface, Sp: Maximum height of the peak Sv: Maximum depth of the valley, Sz: Ten Point Average, Ssk: Asymmetry of the surface, Sku: Kurtosis of the surface. The findings also indicated that the addition of rare earth metals had a positive effect on the abrasion behaviour of G17CrMo5-5 cast steel.

  12. Development of electrolytic process in molten salt media for light rare-earth metals production. The metallic cerium electrodeposition

    International Nuclear Information System (INIS)

    Restivo, T.A.G.

    1994-01-01

    The development of molten salt process and the respective equipment aiming rare-earth metals recovery was described. In the present case, the liquid cerium metal electrodeposition in a molten electrolytes of cerium chloride and an equimolar mixture of sodium and potassium chlorides in temperatures near 800 C was studied. Due the high chemical reactivity of the rare-earth metals in the liquid state and their molten halides, an electrolytic cell was constructed with controlled atmosphere, graphite crucibles and anodes and a tungsten cathode. The electrolytic process variables and characteristics were evaluated upon the current efficiency and metallic product purity. Based on this evaluations, were suggested some alterations on the electrolytic reactor design and upon the process parameters. (author). 90 refs, 37 figs, 20 tabs

  13. Synthesis and structure of alkaline earth and rare earth metal doped C70

    International Nuclear Information System (INIS)

    Takenobu, Taishi; Iwasa, Yoshihiro; Ito, Takayoshi; Mitani, Tadaoki

    2001-01-01

    We have investigated the structure sequence of alkaline earth (A=Ba, Sr) and rare earth metal (R=Eu) doped C 70 binary system. X-ray diffraction measurements revealed that there exist at least four stable phases at x=3, 4, 6, and 9 in A x C 70 and two stable phases at x=3, and 9 in R x C 70 . Among them, structural models are presented for Ba 4 C 70 , Sr 3 C 70 , and Eu 3 C 70 . Ba 4 C 70 takes an analogous structure to orthorhombic Ba 4 C 60 . Sr 3 C 70 and Eu 3 C 70 have monoclinic cell and their diffraction patterns are quite similar to that of Sm 3 C 70 , which involves a unique C 70 -metal-C 70 dimer structure. Preliminary results of Raman spectroscopy and magnetization measurement suggest the highly reduction state for A 9 C 70 and ferromagnetic interaction for Eu x C 70

  14. Anomalous positive flatband voltage shifts in metal gate stacks containing rare-earth oxide capping layers

    KAUST Repository

    Caraveo-Frescas, J. A.

    2012-03-09

    It is shown that the well-known negative flatband voltage (VFB) shift, induced by rare-earth oxide capping in metal gate stacks, can be completely reversed in the absence of the silicon overlayer. Using TaN metal gates and Gd2O3-doped dielectric, we measure a ∼350 mV negative shift with the Si overlayer present and a ∼110 mV positive shift with the Si overlayer removed. This effect is correlated to a positive change in the average electrostatic potential at the TaN/dielectric interface which originates from an interfacial dipole. The dipole is created by the replacement of interfacial oxygen atoms in the HfO2 lattice with nitrogen atoms from TaN.

  15. Modification of radiation sensitivity by salts of the metals beryllium and indium and the rare earths cerium, lanthanum and scandium

    International Nuclear Information System (INIS)

    Floersheim, G.L.

    1995-01-01

    The LD 50 of 46 salts of metals and rare earths (lanthanoids) was determined in mice. Half the LD 50 of the compounds was then combined with lethal radiation (10.5 Gy) and the modification of survival time was scored. Only the metals beryllium and indium and the rare earths cerium, lanthanum and scandium displayed activity in our assay. There were then tested at a wider range of lower doses and reduced survival time in a dose-dependent fashion. This appears to be compatible with enhancement of radiation sensitivity. The interaction of these metals and rare earths with radiation adds a new facet to their toxicological spectrum and, by enhancing radiation effects, may influence estimates of risk. On the other hand, radiosensitizing properties of the metals may be useful for further development of compounds to be used as adjuncts in specific situations of cancer radiotherapy. 31 refs., 1 fig., 1 tab

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

    International Nuclear Information System (INIS)

    Maurer, M.

    1984-01-01

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

  17. Spin-Orbit Qubits of Rare-Earth-Metal Ions in Axially Symmetric Crystal Fields

    Science.gov (United States)

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

    2009-11-01

    Contrary to the well-known spin qubits, rare-earth-metal qubits are characterized by a strong influence of crystal field due to large spin-orbit coupling. At low temperature and in the presence of resonance microwaves, it is the magnetic moment of the crystal-field ground state which nutates (for several μs) and the Rabi frequency ΩR is anisotropic. Here, we present a study of the variations of ΩR(H→0) with the magnitude and direction of the static magnetic field H→0 for the odd Er167 isotope in a single crystal CaWO4:Er3+. The hyperfine interactions split the ΩR(H→0) curve into eight different curves which are fitted numerically and described analytically. These “spin-orbit qubits” should allow detailed studies of decoherence mechanisms which become relevant at high temperature and open new ways for qubit addressing using properly oriented magnetic fields.

  18. Rare earth metal oxides as BH4-tolerance cathode electrocatalysts for direct borohydride fuel cells

    Institute of Scientific and Technical Information of China (English)

    NI Xuemin; WANG Yadong; GUO Feng; YAO Pei; PAN Mu

    2012-01-01

    Rare earth metal oxides (REMO) as cathode electrocatalysts in direct borohydride fuel cell (DBFC) were investigated.The REMO electrocatalysts tested showed favorable activity to the oxygen electro-reduction reaction and strong tolerance to the attack of BH4- in alkaline electrolytes.The simple membraneless DBFCs using REMO as cathode electrocatalyst and using hydrogen storage alloy as anodic electrocatalyst exhibited an open circuit of about 1 V and peak power of above 60 mW/cm2.The DBFC using Sm2O3 as cathode electrocatalyst showed a relatively better performance.The maximal power density of 76.2 mW/cm2 was obtained at the cell voltage of 0.52 V.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  20. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    Energy Technology Data Exchange (ETDEWEB)

    Durczewski, K.; Gajek, Z.; Mucha, J. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)

    2014-11-15

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn{sub 3} and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    International Nuclear Information System (INIS)

    Durczewski, K.; Gajek, Z.; Mucha, J.

    2014-01-01

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn 3 and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Characterization of magnetization processes in nanostructured rare earth-transition metal films

    International Nuclear Information System (INIS)

    Zheng Guangping; Zhan Yangwen; Liu Peng; Li Mo

    2003-01-01

    We synthesize rare earth-transition metal (RE-TM) amorphous films using the electrodeposition method (RE=Nd, Gd and TM=Co). Nanocrystructured RE-TM films are prepared by thermal treatment of as-synthesized films below the glass-crystal transition temperature. Based on the magnetoelastic effect, the magnetization processes in nanostructured samples are characterized by acoustic internal friction measurements using the vibrating-reed technique. Since internal friction and the Young's modulus are sensitive to grain boundary and magnetic domains movement, this technique seems to characterize the effects of nanostructures on the magnetization processes in RE-TM films well. We find that the magnetoelastic effect in nanostructured RE-TM film increases with an increase in grain size

  3. Ground state oxygen holes and the metal-insulator transition in rare earth nickelates

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Thorsten; Bisogni, Valentina; Huang, Yaobo; Strocov, Vladimir [Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Catalano, Sara; Gibert, Marta; Scherwitzl, Raoul; Zubko, Pavlo; Triscone, Jean-Marc [Departement de Physique de la Matiere Condensee, University of Geneva (Switzerland); Green, Robert J.; Balandeh, Shadi; Sawatzky, George [Department of Physics and Astronomy, University of British Columbia, Vancouver (Canada)

    2015-07-01

    Perovskite rare-earth (Re) nickelates ReNiO{sub 3} continue to attract a lot of interest owing to their intriguing properties like a sharp metal to insulator transition (MIT), unusual magnetic order and expected superconductivity in specifically tuned super-lattices. Full understanding of these materials, however, is hampered by the difficulties in describing their electronic ground state (GS). From X-ray absorption (XAS) at the Ni 2p{sub 3/2} edge of thin films of NdNiO{sub 3} and corresponding RIXS maps vs. incident and transferred photon energies we reveal that the electronic GS configuration of NdNiO{sub 3} is composed of delocalized and localized components. Our study conveys that a Ni 3d{sup 8}-like configuration with holes at oxygen takes on the leading role in the GS and the MIT of ReNiO{sub 3} as proposed by recent model theories.

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

    Directory of Open Access Journals (Sweden)

    M. Opiela

    2012-04-01

    Full Text Available The modification of the chemical composition of non-metallic inclusions by rare-earth elements in the new-developed microalloyed steels was discussed in the paper. The investigated steels are assigned to production of forged elements by thermo- mechanical treatment. The steels were melted in a vaccum induction furnace and modification of non-metallic inclusions was carried out by the michmetal in the amount of 2.0 g per 1 kg of steel. It was found that using material charge of high purity and a realization of metallurgical process in vacuous conditions result in a low concentration of sulfur (0.004%, phosphorus (from 0.006 to 0.008% and oxygen (6 ppm. The high metallurgical purity is confirmed by a small fraction of non-metallic inclusions averaging 0.075%. A large majority of non-metallic inclusions are fine, globular oxide-sulfide or sulfide particles with a mean size 17m2. The chemical composition and morphology of non-metallic inclusions was modified by Ce, La and Nd, what results a small deformability of non- metallic inclusions during hot-working.

  5. 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.

  6. Structural and magentic characterization of rare earth and transition metal films grown on epitaxial buffer films on semiconductor substrates

    International Nuclear Information System (INIS)

    Farrow, R.F.C.; Parkin, S.S.P.; Speriosu, V.S.; Bezinge, A.; Segmuller, A.P.

    1989-01-01

    Structural and magnetic data are presented and discussed for epitaxial films of rare earth metals (Dy, Ho, Er) on LaF 3 films on the GaAs(TTT) surface and Fe on Ag films on the GaAs(001) surface. Both systems exhibit unusual structural characteristics which influence the magnetic properties of the metal films. In the case of rare earth epitaxy on LaF 3 the authors present evidence for epitaxy across an incommensurate or discommensurate interface. Coherency strain is not transmitted into the metal which behaves much like bulk crystals of the rare earths. In the case of Fe films, tilted epitaxy and long-range coherency strain are confirmed by X- ray diffractometry. Methods of controlling some of these structural effects by modifying the epitaxial structures are presented

  7. Heavy rare earth elements affect early life stages in Paracentrotus lividus and Arbacia lixula sea urchins

    International Nuclear Information System (INIS)

    Oral, Rahime; Pagano, Giovanni; Siciliano, Antonietta; Gravina, Maria; Palumbo, Anna; Castellano, Immacolata; Migliaccio, Oriana; Thomas, Philippe J.; Guida, Marco; Tommasi, Franca; Trifuoggi, Marco

    2017-01-01

    Background: Heavy rare earth elements (HREEs) have been scarcely studied for their toxicity, in spite of their applications in several technologies. Thus HREEs require timely investigations for their adverse health effects. Methods: Paracentrotus lividus and Arbacia lixula embryos and sperm were exposed to trichloride salts of five HREEs (Dy, Ho, Er, Yb and Lu) and to Ce(III) as a light REE (LREE) reference to evaluate: 1) developmental defects (% DD) in HREE-exposed larvae or in the offspring of HREE-exposed sperm; 2) mitotic anomalies; 3) fertilization success; and 4) reactive oxygen species (ROS) formation, and nitric oxide (NO) and malondialdehyde (MDA) levels. Nominal HREE concentrations were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Results: HREEs induced concentration-related DD increases in P. lividus and A. lixula larvae, ranging from no significant DD increase at 10 −7 M HREEs up to ≅100% DD at 10 −5 M HREE. Larvae exposed to 10 −5 M Ce(III) resulted in less severe DD rates compared to HREEs. Decreased mitotic activity and increased aberration rates were found in HREE-exposed P. lividus embryos. Significant increases in ROS formation and NO levels were found both in HREE-exposed and in Ce(III) embryos, whereas only Ce(III), but not HREEs resulted in significant increase in MDA levels. Sperm exposure to HREEs (10 −5 –10 −4 M) resulted in a concentration-related decrease in fertilization success along with increase in offspring damage. These effects were significantly enhanced for Dy(III), Ho(III), Er(III) and Yb(III), compared to Lu(III) and to Ce(III). Conclusion: HREE-associated toxicity affected embryogenesis, fertilization, cytogenetic and redox endpoints showing different toxicities of tested HREEs. - Highlights: • Different toxicities were exerted by five tested HREEs on sea urchin early life stages. • Sea urchin embryos and sperm were sensitive to HREE levels ranging from 1 to 100 μM, according to

  8. Heavy rare earth elements affect early life stages in Paracentrotus lividus and Arbacia lixula sea urchins

    Energy Technology Data Exchange (ETDEWEB)

    Oral, Rahime [Ege University, Faculty of Fisheries, TR-35100 Bornova, İzmir (Turkey); Pagano, Giovanni, E-mail: gbpagano@tin.it [“Federico II” University of Naples, Department of Chemical Sciences, I-80126 Naples (Italy); Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples (Italy); Siciliano, Antonietta; Gravina, Maria [“Federico II” University of Naples, Department of Biology, I-80126 Naples (Italy); Palumbo, Anna; Castellano, Immacolata; Migliaccio, Oriana [Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples (Italy); Thomas, Philippe J. [Environment and Climate Change Canada, Science & Technology Branch, National Wildlife Research Center – Carleton University, Ottawa, Ontario, Canada K1A 0H3 (Canada); Guida, Marco [“Federico II” University of Naples, Department of Biology, I-80126 Naples (Italy); Tommasi, Franca [University of Bari, Department of Biology, Bari (Italy); Trifuoggi, Marco [“Federico II” University of Naples, Department of Chemical Sciences, I-80126 Naples (Italy)

    2017-04-15

    Background: Heavy rare earth elements (HREEs) have been scarcely studied for their toxicity, in spite of their applications in several technologies. Thus HREEs require timely investigations for their adverse health effects. Methods: Paracentrotus lividus and Arbacia lixula embryos and sperm were exposed to trichloride salts of five HREEs (Dy, Ho, Er, Yb and Lu) and to Ce(III) as a light REE (LREE) reference to evaluate: 1) developmental defects (% DD) in HREE-exposed larvae or in the offspring of HREE-exposed sperm; 2) mitotic anomalies; 3) fertilization success; and 4) reactive oxygen species (ROS) formation, and nitric oxide (NO) and malondialdehyde (MDA) levels. Nominal HREE concentrations were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). Results: HREEs induced concentration-related DD increases in P. lividus and A. lixula larvae, ranging from no significant DD increase at 10{sup −7} M HREEs up to ≅100% DD at 10{sup −5} M HREE. Larvae exposed to 10{sup −5} M Ce(III) resulted in less severe DD rates compared to HREEs. Decreased mitotic activity and increased aberration rates were found in HREE-exposed P. lividus embryos. Significant increases in ROS formation and NO levels were found both in HREE-exposed and in Ce(III) embryos, whereas only Ce(III), but not HREEs resulted in significant increase in MDA levels. Sperm exposure to HREEs (10{sup −5}–10{sup −4} M) resulted in a concentration-related decrease in fertilization success along with increase in offspring damage. These effects were significantly enhanced for Dy(III), Ho(III), Er(III) and Yb(III), compared to Lu(III) and to Ce(III). Conclusion: HREE-associated toxicity affected embryogenesis, fertilization, cytogenetic and redox endpoints showing different toxicities of tested HREEs. - Highlights: • Different toxicities were exerted by five tested HREEs on sea urchin early life stages. • Sea urchin embryos and sperm were sensitive to HREE levels ranging from 1 to 100

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

    International Nuclear Information System (INIS)

    Fidler, J.

    1982-01-01

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

  10. NEW RARE EARTH ELEMENT ABUNDANCE DISTRIBUTIONS FOR THE SUN AND FIVE r-PROCESS-RICH VERY METAL-POOR STARS

    International Nuclear Information System (INIS)

    Sneden, Christopher; Lawler, James E.; Den Hartog, Elizabeth A.; Cowan, John J.; Ivans, Inese I.

    2009-01-01

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

  11. Recovery of fluorine, uranium, and rare earth metal values from phosphoric acid by-product brine raffinate

    International Nuclear Information System (INIS)

    Wamser, C.A.; Bruen, C.P.

    1976-01-01

    A method for recovering substantially all of the fluorine and uranium values and at least 90 percent of the rare earth metal values from brine raffinate obtained as by-product in the production of phosphoric acid by the hydrochloric acid decomposition of tricalcium phosphate minerals is described. A basically reacting compound is added to the brine raffinate to effect a pH 9 or greater, whereby fluorine, uranium and rare earth metal values are simultaneously precipitated. These values may then be separately recovered from the precipitate by known processes

  12. Effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel - Part 1

    International Nuclear Information System (INIS)

    Kim, Soon-Tae; Jeon, Soon-Hyeok; Lee, In-Sung; Park, Yong-Soo

    2010-01-01

    To elucidate the effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel, a metallographic examination, potentiodynamic and potentiostatic polarization tests, a SEM-EDS and a SAM analysis of inclusion, austenite phase and ferrite phase were conducted. The addition of rare earth metals to the base alloy led to the formation of (Mn, Cr, Si, Al, Ce) oxides and (Mn, Cr, Si, Ce) oxides, which improved the resistance to pitting corrosion and caused a decrease in the preferential interface areas for the initiation of the pitting corrosion.

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  15. Recent advances in syntheses and biomedical applications of nano-rare earth metal-organic framework materials

    Directory of Open Access Journals (Sweden)

    Xin Pengyan

    2017-12-01

    Full Text Available In recent years,the syntheses of nano-rare earth metal-organic framework (MOF materials and their applications in biomedicine,especially in the diagnosis and treatment of cancer have attracted extensive attentions.On the one hand,nano-rare earth MOFs,which have unique optical and magnetic properties,are promising multimodal imaging contrast agents for biomedical imaging,such as fluorescence imaging and magnetic resonance imaging.On the other hand,nano-rare earth MOFs have various compositions and structures,and excellent intrinsic properties such as large specific surface area,high pore volume and tunable pore size,which enable them to perform as promising nanoplatforms for drug delivery.Therefore,nano-rare earth MOFs may provide a new platform for the development of diagnostic and therapeutic reagents.In this article,the recent advances in the syntheses of nano-rare earth MOFs and their applications in biomedicine are summarized.

  16. Reduction of residual gas in a sputtering system by auxiliary sputter of rare-earth metal

    International Nuclear Information System (INIS)

    Li Dejie

    2002-01-01

    In film deposition by sputtering, the oxidation and nitrification of the sputtered material lead to degradation of film quality, particularly with respect to metal sulfide films. We propose to use auxiliary sputtering as a method to produce a fresh film of rare-earth metal, usually dysprosium (Dy), that absorbs the active gases in a sputtering system, greatly reducing the background pressure and protecting the film from oxidation and nitrification effectively. The influence of the auxiliary sputtering power consumption, sputtering time, and medium gas pressure on the background pressure in the vacuum chamber is investigated in detail. If the auxiliary sputtering power exceeds 120 W and the sputtering time is more than 4 min, the background pressure is only one fourth of the ultimate pressure pumped by an oil diffusion pump. The absorption activity of the sputtered Dy film continues at least an hour after completion of the auxiliary sputter. Applied to film deposition of Ti and ZnS, this technique has been proven to be effective. For the Ti film, the total content of N and O is reduced from 45% to 20% when the auxiliary sputtering power of Dy is 120 W, and the sputtering time is 20 min. In the case of ZnS, the content of O is reduced from 8% to 2%

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

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

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

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

    KAUST Repository

    Eddaoudi, Mohamed

    2017-04-13

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-06-30

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

  20. Rare earths and actinides

    International Nuclear Information System (INIS)

    Coqblin, B.

    1982-01-01

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

  1. Equilibrium and non-equilibrium extraction separation of rare earth metals in presence of diethylenetriaminepentaacetic acid in aqueous phase

    International Nuclear Information System (INIS)

    Azis, Abdul; Teramoto, Masaaki; Matsuyama, Hideto.

    1995-01-01

    Equilibrium and non-equilibrium extraction separations of rare earth metals were carried out in the presence of chelating agent in the aqueous phase. The separation systems of the rare earth metal mixtures used were Y/Dy, Y/Ho, Y/Er and Y/Tm, and the chelating agent and the extractant were diethylenetriaminepentaacetic acid (DTPA) and bis (2,4,4-trimethylpentyl) phosphinic acid (CYANEXR 272), respectively. For Y/Dy and Y/Ho systems, higher selectivities were obtained in equilibrium separation compared with those in non-equilibrium separation. On the other hand, the selectivities in non-equilibrium separation were higher for Y/Er and Y/Tm systems. In the separation condition suitable to each system, the addition of DTPA to the aqueous phase was found to be very effective for obtaining higher selectivities. The distribution ratios of the rare earth metals and the selectivities in the equilibrium separations obtained experimentally were thoroughly analyzed by considering various equilibria such as the extraction equilibrium and the complex formation equilibrium between rare earth metals and DTPA in the aqueous phase. Moreover, the extraction rates and the selectivities in the non-equilibrium separations were also analyzed by the extraction model considering the dissociation reactions of the rare earth metal-DTPA complexes in the aqueous stagnant layer. Based on these analyses, we presented an index which is useful for selecting the optimum operation mode. Using this index, we can predict that the selectivities under equilibrium conditions are higher than those under non-equilibrium conditions for Y/Dy and Y/Ho systems, while for Y/Er and Y/Tm systems, higher selectivities are obtained under non-equilibrium conditions. The experimental results were in agreement with predictions by this index. Further, the selectivities in various systems including other chelating agents and extractants were discussed based on this index. (J.P.N.)

  2. Trace elements in land plants: concentration ranges and accumulators of rare earths, Ba, Ra, Mn, Fe, Co and heavy halogens

    International Nuclear Information System (INIS)

    Koyama, M.; Shirakawa, M.; Takada, J.; Katayama, Y.; Matsubara, T.

    1987-01-01

    More than 2000 samples of land plant leaves, mostly of tree, were analyzed by neutron activation analysis in order to find out macroscopic relations between distributions of chemical elements in plants and soil characteristics. The distributions of the elements in plants were also examined from the view point of botanical taxonomy or phylogeny. New species which accumulate Co, rare earths, Ba, Ra, heavy halogens and some other elements were found. Capability or potentiality for accumulating elements could be related to higher ranks of taxonomy, that is, genus or family. The nature of soil is also found to have profound effects on the extent of accumulation of elements in plants. (author)

  3. Synthesis and characterization of rare-earth oxide transition-metal arsenides and selenides

    International Nuclear Information System (INIS)

    Peschke, Simon Friedrich

    2017-01-01

    The present thesis includes two different quaternary systems that have been studied extensively. On the one hand, several samples of the REFeAsO_1_-_xF_x family of iron-based superconductors were prepared using a novel solid state metathesis reaction, which also provided a possibility to prepare late rare-earth compounds of this family at ambient pressure. Comparison of structural and physical properties of those samples with samples from conventional solid state and high pressure syntheses revealed both, commonalities as well as striking differences. The observations gave reason to the conclusion that superconducting properties strongly depend, beside electronic infl uence, on the structural parameters. On the other hand, the quaternary system RE-T-Se-O with T = Ti-Mn was investigated using a NaI/KI flux mediated synthesis route. It has been shown that oC -La_2O_2MnSe_2 is exclusively accessible in su fficient purity by the use of a fl ux material. Therefore, further syntheses in this quaternary system were performed by a flux mediated synthesis route leading to a large amount of new materials. Among them, a new polymorph mC-La_2O_2MnSe_2 which forms, together with La_4MnSe_3O_4 and La_6MnSe_4O_6, the series La_2_n_+_2MnSe_n_+_2O_2_n_+_2. In addition, the alternative preparation method also enabled a large scale synthesis of the first examples of rare-earth chromium oxyselenides with chromium in the oxidation state +II, namely RE_2CrSe_2O_2 (RE = La-Nd), which opened the door to study their magnetism in detail by powder neutron diffraction and muon spin rotation techniques. Research into the La-V-Se-O system revealed the first fi ve quaternary compounds of this family with interesting magnetic properties including ferromagnetism, antiferromagnetism, metamagnetism and more complex behaviour. In addition, the crystal structure of two new quaternary titanium containing oxyselenides were identifi ed and revealed unique structural building blocks that have not been

  4. A Complete Design of a Rare Earth Metal-Free Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Petter Eklund

    2014-05-01

    Full Text Available The price of rare-earth metals used in neodymium-iron-boron (NdFeB permanent magnets (PMs has fluctuated greatly recently. Replacing the NdFeB PMs with more abundant ferrite PMs will avoid the cost insecurity and insecurity of supply. Ferrite PMs have lower performance than NdFeB PMs and for similar performance more PM material has to be used, requiring more support structure. Flux concentration is also necessary, for example, by a spoke-type rotor. In this paper the rotor of a 12 kW NdFeB PM generator was redesigned to use ferrite PMs, reusing the existing stator and experimental setup. Finite element simulations were used to calculate both electromagnetic and mechanical properties of the design. Focus was on mechanical design and feasibility of construction. The result was a design of a ferrite PM rotor to be used with the old stator with some small changes to the generator support structure. The new generator has the same output power at a slightly lower voltage level. It was concluded that it is possible to use the same stator with either a NdFeB PM rotor or a ferrite PM rotor. A ferrite PM generator might require a larger diameter than a NdFeB generator to generate the same voltage.

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

    DEFF Research Database (Denmark)

    Szpunar, B.; Lindgård, Per-Anker

    1977-01-01

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

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

    Science.gov (United States)

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

    2012-06-18

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

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

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Danielsen, O.

    1975-01-01

    results are given for the magnetization agreeing with experiment for Gd, Tb, and Dy. For Tb and Dy the zero-point deviations were found to be 0.05μB and 0.08μB, respectively, and the ratio [b(T)-b(0)]/[ΔM(T)-ΔM(0)] is approximately 1/3 for all temperatures below 100 K. This gives rise to large corrections......The contributions to the macroscopic-anisotropy constants and resonance energy from crystal-field anisotropy, magnetoelastic effects in the frozen and flexible lattice model, and two-ion interactions have been found for all terms allowed in a crystal of hexagonal symmetry. The temperature...... 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. Crystallographic and spectroscopic investigations on nine metal-rare-earth silicates with the apatite structure type

    International Nuclear Information System (INIS)

    Wierzbicka-Wieczorek, Maria; Goeckeritz, Martin; Kolitsch, Uwe; Lenz, Christoph; Giester, Gerald

    2015-01-01

    Nine silicates with the apatite structure type (space group P6 3 /m) containing both rare-earth elements (REEs: Pr, Nd, Sm, Tb, Ho and Er) and various metals (K, Sr, Ba and Cd) were synthesised by high-temperature flux-growth techniques and characterised by single-crystal X-ray diffraction, scanning electron microscopy, Raman spectroscopy and laser-induced photoluminescence spectroscopy. In all of the compounds, the 6h Wyckoff position is predominantly or solely occupied by REE 3+ cations, whereas the cations shows a mixed occupancy at the larger, nine-coordinate 4f site with 55-75 % of REE 3+ cations and 45-25 % of other metal cations. The O4 (''free'' oxygen) site is fully occupied by O 2- anions, except for a Ba-Pr member with full occupancy by F - anions. The refined formulas are Cd 2 Er 8 (SiO 4 ) 6 O 2 , Cd 2 Tb 8 (SiO 4 ) 6 O 2 , KHo 9 (SiO 4 ) 6 O 2 , KTb 9 (SiO 4 ) 6 O 2 , KSm 9 (SiO 4 ) 6 O 2 , Sr 2 Nd 8 (SiO 4 ) 6 O 2 , Ba 2 Nd 8 (SiO 4 ) 6 O 2 , Ba 2 Sm 8 (SiO 4 ) 6 O 2 and Ba 4 Pr 6 (SiO 4 ) 6 F 2 . Changes in the metaprism twist angle (φ) and correlations between the unit-cell parameters, average cationic radii (of M + /M 2+ -REE 3+ pairs) and the chemistry of both the synthesised M + /M 2+ -REE 3+ silicate apatites and those reported previously are evaluated. Photoluminescence measurements of undoped samples yielded emission bands in the visible region from green to red; therefore, these compounds are potential candidates for luminescent materials. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

  10. Thermodynamic Considerations of Direct Oxygen Removal from Titanium by Utilizing the Deoxidation Capability of Rare Earth Metals

    Science.gov (United States)

    Okabe, Toru H.; Zheng, Chenyi; Taninouchi, Yu-ki

    2018-06-01

    Oxygen removal from metallic Ti is extremely difficult and, currently, there is no commercial process for effectively deoxidizing Ti or its alloys. The oxygen concentration in Ti scraps is normally higher than that in virgin metals such as in Ti sponges produced by the Kroll process. When scraps are remelted with virgin metals for producing primary ingots of Ti or its alloys, the amount of scrap that can be used is limited owing to the accumulation of oxygen impurities. Future demands of an increase in Ti production and of mitigating environmental impacts require that the amount of scrap recycled as a feed material of Ti ingots should also increase. Therefore, it is important to develop methods for removing oxygen directly from Ti scraps. In this study, we evaluated the deoxidation limit for β-Ti using Y or light rare earth metals (La, Ce, Pr, or Nd) as a deoxidant. Thermodynamic considerations suggest that extra-low-oxygen Ti, with an oxygen concentration of 100 mass ppm or less can be obtained using a molten salt equilibrating with rare earth metals. The results presented herein also indicate that methods based on molten salt electrolysis for producing rare earth metals can be utilized for effectively and directly deoxidizing Ti scraps.

  11. Investor's and procurement guide South Africa. Pt. 1. Heavy minerals, rare earth elements, antimony

    Energy Technology Data Exchange (ETDEWEB)

    Graupner, Torsten; Schwarz-Schampera, Ulrich [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Berlin (Germany); Hammond, Napoleon Q.; Opperman, Rehan; Long' a Tongu, Elisa; Kenan, Abdul O.; Nondula, Unathi; Tsanwani, Matamba [Council for Geoscience (CGS), Pretoria (South Africa). Dept. of Mineral Resources Development; Liedke, Maren; Marbler, Herwig [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Berlin (Germany). Deutsche Rohstoffagentur (DERA)

    2014-03-15

    This is the first part of the ''Investor's and Procurement Guide South Africa'', a handbook for investing and doing business in South Africa's mineral industry. It is anticipated that this publication will aid potential investors into considering South Africa as an investment destination, not only for raw materials, but also for related industries. This manual supplements the many publications available on the economic geology and mineral wealth in South Africa and has been designed to guide prospective and current investors, suppliers and mine equipment exporters through the process of doing business in Africa's biggest and dynamic economy. As well as detailing the mineral raw materials heavy minerals, rare-earth metals and antimony, the handbook provides a general introduction to South Africa and its infrastructure, the economical, political and judicial frame of the South African mining industry and an overview of the economic geology. South Africa has a long and complex geological history which dates back in excess of 3.6 billion years. The country has a vast mineral wealth, undoubtedly due to the fact that a significant proportion of the Archaean and younger rocks have been preserved. The mining of the enormous Witwatersrand gold deposits, commencing in 1886, has led to the establishment of South Africa's well-developed infrastructure and to the sustained growth of an industrial and service sector in the country. With the world's largest resources of PGMs, gold, chromite, vanadium and manganese and significant resources of iron, coal and numerous other minerals and metals, the minerals industry will continue to play a pivotal role in the growth of South Africa's economy in the foreseeable future. South Africa is one of the top destinations in Africa for foreign direct investments. South African headquartered companies have been major investors into foreign direct investments on the African continent in the past

  12. Lithium and Beryllium By-product Recovery from the Round Top Mountain, Texas, Peraluminous Rhyolite Heavy Rare Earth Deposit

    Science.gov (United States)

    Pingitore, N. E., Jr.; Clague, J. W.; Gorski, D.

    2016-12-01

    The technology metals Li and Be combine low mass and unique properties. Li batteries are critical in applications at scales from micro-electronics to automotive and grid storage. Low mass Be structural components are essential in aerospace/defense applications and in non-sparking BeCu alloy oilfield tools. Most Li is sourced from desert salarsin the "Lithium Triangle" of Argentina—Bolivia—Chile. In contrast, Materion Corp mines >80% of global Be at Spor Mountain, UT. The massive peraluminous rhyolite heavy rare earth deposit at Round Top Mountain, TX is also enriched in Li, 500 ppm, and Be, 50 ppm. 2016 prices of 7000/tonne Li2CO3 (19% Li) and 1000/kg Be metal suggest favorable economics to extract Li and Be as by-products of HREE mining. Li and some Be are hosted in annite biotite that comprises up to 5% of the rhyolite. Texas Mineral Resources Corp proposes to heap leach crushed rhyolite with dilute H2SO4to release the yttrofluorite-hosted HREEs. At bench scale the annite biotite dissolves, but not quartz and feldspars (>90% of the rock). A series of 40 high-yield laboratory tests at various acid strength, particle size, and exposure time released up to 350 ppm (70%) of the Li and 14 ppm (30%) of the Be. For a 20,000 tonne/day operation, these recoveries correspond to daily production of >3 tonnes Li and 250 kg Be. Higher Li and Be recoveries also increased yields of gangue elements, Fe & Al, into solution. This complicates subsequent separation of Li, Be, and HREEs from the pregnant leach solution. Recovery of target HREEs did not increase beyond 200 ppm Li and 8 ppm Be recovery. Greater Li and Be recoveries increased acid consumption. Thus the "sweet spot" economics for heap leach is likely under conditions of acid strength, grain size, and exposure time that do not maximize by-product Li and Be recoveries. Evolving market prices for the full target element suite and additional costs to recover and purify the Li and Be must also be considered.

  13. 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...

  14. Tetrahydropentalenyl-phosphazene constrained geometry complexes of rare-earth metal alkyls.

    Science.gov (United States)

    Hangaly, Noa K; Petrov, Alexander R; Elfferding, Michael; Harms, Klaus; Sundermeyer, Jörg

    2014-05-21

    Reactions of Cp™HPPh2 (1, diphenyl(4,4,6,6-tetramethyl-1,4,5,6-tetrahydropentalen-2-yl)phosphane) with the organic azides AdN3 and DipN3 (Ad = 1-adamantyl; Dip = 2,6-di-iso-propylphenyl) led to the formation of two novel CpPN ligands: P-amino-cyclopentadienylidene-phosphorane (Cp™PPh2NHAd; L(Ad)H) and P-cyclopentadienyl-iminophosphorane (Cp™HPPh2NDip; L(Dip)H). Both were characterized by NMR spectroscopy and X-ray structure analysis. For both compounds only one isomer was observed. Neither possesses any detectable prototropic or elementotropic isomers. Reactions of these ligands with [Lu(CH2SiMe3)3(thf)2] or with rare-earth metal halides and three equivalents of LiCH2SiMe3 produced the desired bis(alkyl) Cp™PN complexes: [{Cp™PN}M(CH2SiMe3)2] (M = Sc (1(Ad), 1(Dip)), Lu (2(Ad), 2(Dip)), Y (3(Ad), 3(Dip)), Sm (4(Ad)), Nd (5(Ad)), Pr (6(Ad)), Yb (7(Ad))). These complexes were characterized by extensive NMR studies for the diamagnetic and the paramagnetic complexes with full signal assignment. An almost mirror inverted order of the paramagnetic shifts has been observed for ytterbium complex 7(Ad) compared to 4(Ad), 5(Ad) and 6(Ad). For the assignment of the NMR signals [{η(1) : η(5)-C5Me4PMe2NAd}Yb(CH2SiMe3)2] 7 was synthesized, characterized and the (1)H NMR signals were compared to 7(Ad) and to other paramagnetic lanthanide complexes with the same ligand. 1(Ad), 2(Ad), 2(Dip), 3(Ad) and 3(Dip) were characterized by X-ray structure analysis revealing a sterically congested constrained geometry structure.

  15. Metallothermic reduction of rare earth oxides

    International Nuclear Information System (INIS)

    Sharma, R.A.

    1986-01-01

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

  16. Synthesis and characterization of rare-earth oxide transition-metal arsenides and selenides

    Energy Technology Data Exchange (ETDEWEB)

    Peschke, Simon Friedrich

    2017-04-06

    The present thesis includes two different quaternary systems that have been studied extensively. On the one hand, several samples of the REFeAsO{sub 1-x}F{sub x} family of iron-based superconductors were prepared using a novel solid state metathesis reaction, which also provided a possibility to prepare late rare-earth compounds of this family at ambient pressure. Comparison of structural and physical properties of those samples with samples from conventional solid state and high pressure syntheses revealed both, commonalities as well as striking differences. The observations gave reason to the conclusion that superconducting properties strongly depend, beside electronic infl uence, on the structural parameters. On the other hand, the quaternary system RE-T-Se-O with T = Ti-Mn was investigated using a NaI/KI flux mediated synthesis route. It has been shown that oC -La{sub 2}O{sub 2}MnSe{sub 2} is exclusively accessible in su fficient purity by the use of a fl ux material. Therefore, further syntheses in this quaternary system were performed by a flux mediated synthesis route leading to a large amount of new materials. Among them, a new polymorph mC-La{sub 2}O{sub 2}MnSe{sub 2} which forms, together with La{sub 4}MnSe{sub 3}O{sub 4} and La{sub 6}MnSe{sub 4}O{sub 6}, the series La{sub 2n+2}MnSe{sub n+2}O{sub 2n+2}. In addition, the alternative preparation method also enabled a large scale synthesis of the first examples of rare-earth chromium oxyselenides with chromium in the oxidation state +II, namely RE{sub 2}CrSe{sub 2}O{sub 2} (RE = La-Nd), which opened the door to study their magnetism in detail by powder neutron diffraction and muon spin rotation techniques. Research into the La-V-Se-O system revealed the first fi ve quaternary compounds of this family with interesting magnetic properties including ferromagnetism, antiferromagnetism, metamagnetism and more complex behaviour. In addition, the crystal structure of two new quaternary titanium containing

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

    International Nuclear Information System (INIS)

    Day, R.

    1978-08-01

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

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

    International Nuclear Information System (INIS)

    Schleid, Thomas; Hartenbach, Ingo

    2016-01-01

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

  19. On fluorozirconates and fluorohafnates of rare earths

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  20. Trace elements in land plants: concentration ranges and accumulators of rare earths, Ba, Ra, Mn, Fe, Co, and heavy halogens

    International Nuclear Information System (INIS)

    Koyama, Mutsuo; Shirakawa, Masahiro; Takada, Jitsuya; Katayama, Yukio; Matsubara, Takashi

    1986-01-01

    More than 2000 samples of land plant leaves, mostly of tree, have been analysed by neutron activation analysis in order to find out macroscopic relations between distributions of chemical elements in plants and soil characteristics. The distributions of the elements in plants were also examined from the view point of botanical taxonomy or phylogeny. New species which accumulate Co, rare earths, Ba, Ra, heavy halogens and other elements have been found. Capability or potentiality for accumulating elements could be related to primarily to species. In several cases, however, it is related to higher ranks of taxonomy, that is, genus or family. The nature of soil is also found to have profound effects on the extent of accumulation of elements in plants. (author)

  1. Contribution to the study of diffusion in rare earth metals and actinides

    International Nuclear Information System (INIS)

    Marbach, Gabriel.

    1978-07-01

    This work describes several experiments carried out in order to understand the process of self diffusion in rare earth and actinides (self diffusion of body centered cubic γ neptunium, diffusion of gadolinium in body centered delta cerium, measurement of the activation volume of face centered cubic γ cerium). The unstable electronic structure of some elements cannot be correlate with anomalous diffusion properties. In fact the diffusion parameters of neptunium and plutonium are similar (high diffusivity and low activation energy) whereas the electronic structure of neptunium is stable and that of plutonium is temperature dependent. The negative activation volume of the body centered cubic phases of plutonium and cerium does not indicate a particular diffusion mechanism since self diffusion is faster under pressure in face centered cubic γ cerium where a vacancy mechanism is assumed according to earlier results. The vacancy mechanism is the most probable diffusion process in the body centered cubic and compact phases of rare earths and actinides [fr

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

    International Nuclear Information System (INIS)

    Kawano, S.

    2003-01-01

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

  3. Preparation and physical properties of rare earth, alkaline earth, and transition metal ternary chalcogenides

    International Nuclear Information System (INIS)

    Georgobiani, A.N.

    1997-01-01

    A study was made on current-voltage characteristics, temperature dependences of electric conductivity and currents of thermoinduced depolarization of monocrystals, including EuGa 2 S 4 and (Ga 2 S 3 ) 1-x (Eu 2 O 3 ) x solid solutions. It is shown that these compounds, activated by europium, cerium, neodymium and other rare earths, manifest effective luminescence under the effect of ultraviolet and X-radiation, as well as under the effect of electron beams and electric field

  4. Fate and transport of trace metals and rare earth elements in the Snake River, an AMD/ARD-impacted watershed. Montezuma, Colorado USA.

    Science.gov (United States)

    McKnight, D. M.; Rue, G.

    2017-12-01

    Recent research in Snake River Watershed, located near the historic boomtown of Montezuma and adjacent the Continental Divide in the Colorado Rocky Mountains, has revealed the distinctive occurrence of rare earth elements (REE) at high concentrations. Here the weathering of the mineralized lithology naturally generates acid rock drainage (ARD) in addition to drainage recieved from abandoned mine adits throughout the area, results in aqueous REE concentrations three orders of magnitude higher than in most major rivers. The dominant mechanism responsible for this enrichment; their dissolution from secondary and accessory mineral stocks, abundant in REEs, promoted by the low pH waters generated from geochemical weathering of disseminated sulfide minerals. While REEs behave conservatively in acidic conditions, as well as in the presence of stabilizing ligands such as sulfate, downstream circumneutral inputs from pristine streams and a rising pH are resulting in observed fractional losses of heavy rare earth elements as well as partitioning towards colloidal and solid phases. These finding in combination with the established role of dissolved organic matter (DOM) in binding with both trace metals and REEs, suggest that competitive interactions, complexation, and scavenging are likely contributing to these proportional losses. However, outstanding questions yet remain regarding the effects of an increasing flux of trace metals as well as REEs from the Snake River Watershed into Dillon Reservoir, a major drinking water supply for the City of Denver, in part due to hydroclimatological drivers that are enhancing geochemical weathering and reducing groundwater recharge in alpine areas across the Colorado Rockies. Based on these findings also we seek to broaden this body of work to further investigate the behavior of rare earth elements (REE) in other aquatic environment as well the influence of trace metals, DOM, and pH in altering their reactivity and subsequent watershed

  5. Determination of metals and rare earths in leach solution of phosphogypsum by instrumental neutron activation analysis (INAA)

    International Nuclear Information System (INIS)

    Costa, Gabriela J.L.; Saueia, Catia H.R.; Mazzilli, Barbara P.

    2011-01-01

    The phosphogypsum is a sub-product of the fertilizer industries and is composed of the gypsum matrix (CaSO 4 .2H 2 O) which naturally contains high tenors of impurities such as 2P O 5 and metals coming from the original phosphat rock. The Brazilian phosphogypsum and the various uses has been researched through his elementary and radiochemistry characterization. This work determine the metals (As, Ba, Co and Se) and rare earths (La, Ce, Sm, Eu, Tb and Lu) presents in samples of phosphogypsum leach solutions

  6. Rare earths 1998 market update

    International Nuclear Information System (INIS)

    Tourre, J.M.

    1998-01-01

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

  7. Rare earths: occurrence, production and applications

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  8. Coordination compounds of metals with imidazoles and benzimidazoles. [Metals: V, Th, Mo, Cd, rare earths, etc

    Energy Technology Data Exchange (ETDEWEB)

    Novikova, G A; Molodkin, A K; Kukalenko, S S

    1988-12-01

    Methods of preparation, composition and structure of UO/sub 2//sup 2+/, Th/sup 4+/, Mo/sup 3+/, Cd/sup 2+/, Ln/sup 3+/ metal ion complexes with imidazoles and benzimidazoles are considered in reviews of native and foreign literature of up to 1985. Complexes are customarily prepared by direct interaction of ligands with inorganic salts in different organic solvents. Complex composition is defined by the nature of complexing metal and inorganic salt anion, ligand volume and basicity, as well as solvent characteristics. Effect of R substituent in imidazole and benzimidazole side chain on composition of coordination compounds is considered.

  9. Living catalyzed-chain-growth polymerization and block copolymerization of isoprene by rare-earth metal allyl precursors bearing a constrained-geometry-conformation ligand.

    Science.gov (United States)

    Jian, Zhongbao; Cui, Dongmei; Hou, Zhaomin; Li, Xiaofang

    2010-05-07

    Aminophenyl functionalized cyclopentadienyl ligated rare-earth metal allyl mediated cationic systems display high cis-1,4 selectivity for the polymerization of isoprene, and living reversible and rapid chain transfer to aluminium additives.

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

    International Nuclear Information System (INIS)

    Ning Yang

    2004-01-01

    Thermal expansion anomalies of R 2 Fe 14 B and R 2 Fe 17 C x (x = 0,2) (R Y, Nd, Gd, Tb, Er) stoichiometric compounds are studied with high-energy synchrotron X-ray powder diffraction using Debye-Schemer geometry in temperature range 10K to 1000K. Large spontaneous magnetostriction up to their Curie temperatures (T c ) is observed. The a-axes show relatively larger invar effects than c-axes in the R 2 Fe 14 B compounds whereas the R 2 Fe 17 C x show the contrary anisotropies. The iron sub-lattice is shown to dominate the spontaneous magnetostriction of the compounds. The contribution of the rare earth sublattice is roughly proportional to the spin magnetic moment of the rare earth in the R 2 Fe 14 B compounds but in R 2 Fe 17 C x , the rare earth sub-lattice contribution appears more likely to be dominated by the local bonding. The calculation of spontaneous magnetostrain of bonds shows that the bonds associated with Fe(j2) sites in R 2 Fe 14 B and the dumbbell sites in R 2 Fe 17 C x have larger values, which is strongly related to their largest magnetic moment and Wigner-Seitz atomic cell volume. The roles of the carbon atoms in increasing the Curie temperatures of the R 2 Fe 17 compounds are attributed to the increased separation of Fe hexagons. The R 2 Fe 17 and R 2 Fe 14 B phases with magnetic rare earth ions also show anisotropies of thermal expansion above T c . For R 2 Fe 17 and R 2 Fe 14 B the a a /a c > 1 whereas the anisotropy is reversed with the interstitial carbon in R 2 Fe 17 . The average bond magnetostrain is shown to be a possible predictor of the magnetic moment of Fe sites in the compounds. Both of the theoretical and phenomenological models on spontaneous magnetostriction are discussed and a Landau model on the spontaneous magnetostriction is proposed

  11. A Unique Yttrofluorite-Hosted Giant Heavy Rare Earth Deposit: Round Top Mountain, Hudspeth County, Texas, USA

    Science.gov (United States)

    Pingitore, N. E.; Clague, J. W.; Gorski, D.

    2013-12-01

    Round Top Mountain is a surface-exposed peraluminous rhyolite laccolith, enriched in heavy rare earth elements, as well as niobium-tantalum, beryllium, lithium, fluorine, tin, rubidium, thorium, and uranium. The extreme extent of the deposit (diameter one mile) makes it a target for recovery of valuable yttrium and HREEs, and possibly other scarce elements. The Texas Bureau of Economic Geology estimated the laccolith mass as at least 1.6 billion tons. A Preliminary Economic Assessment for Texas Rare Earth Resources listed an inferred mineral resource of 430,598,000 kg REOs (rare earth oxides), with over 70% Y+HREEs (YHREE). Put in global perspective, China is thought to produce ~25,000 tons YHREE per year, and exports but a small fraction of that. Because of the extremely fine grain size of the late-phase fluorine-carried critical fluid mineralization, it has not been clear which minerals host the YHREEs. X-ray Absorption Spectroscopy experiments at the Stanford Synchrotron Radiation Lightsource revealed that virtually all of the YHREE content resides in yttrofluorite, rather than in the other reported REE minerals in the deposit, bastnaesite and xenotime. The extended x-ray absorption fine structure (XAFS) spectra of the sample suite were all quite similar, and proved a close match to known model compound specimens of yttrofluorite from two locations, in Sweden and New Mexico. Small spectral variation between the two model compounds and among the samples is attributable to the variable elemental composition and altervalent substitutional nature of yttrofluorite (Ca [1-x] Y,REE [x])F[2+x]. We found no other reported deposit in the world in which yttrofluorite is the exclusive, or even more than a minor, YHREE host mineral. Leaching experiments show that the YHREEs are easily liberated by dissolution with dilute sulfuric acid, due to the solubility of yttrofluorite. Flotation separation of the yttrofluorite had been demonstrated, but was rendered inefficient by the

  12. Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2012-02-20

    Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

  13. Experimental demonstration of efficient and selective population transfer and qubit distillation in a rare-earth-metal-ion-doped crystal

    International Nuclear Information System (INIS)

    Rippe, Lars; Nilsson, Mattias; Kroell, Stefan; Klieber, Robert; Suter, Dieter

    2005-01-01

    In optically controlled quantum computers it may be favorable to address different qubits using light with different frequencies, since the optical diffraction does not then limit the distance between qubits. Using qubits that are close to each other enables qubit-qubit interactions and gate operations that are strong and fast in comparison to qubit-environment interactions and decoherence rates. However, as qubits are addressed in frequency space, great care has to be taken when designing the laser pulses, so that they perform the desired operation on one qubit, without affecting other qubits. Complex hyperbolic secant pulses have theoretically been shown to be excellent for such frequency-addressed quantum computing [I. Roos and K. Molmer, Phys. Rev. A 69, 022321 (2004)] - e.g., for use in quantum computers based on optical interactions in rare-earth-metal-ion-doped crystals. The optical transition lines of the rare-earth-metal-ions are inhomogeneously broadened and therefore the frequency of the excitation pulses can be used to selectively address qubit ions that are spatially separated by a distance much less than a wavelength. Here, frequency-selective transfer of qubit ions between qubit states using complex hyperbolic secant pulses is experimentally demonstrated. Transfer efficiencies better than 90% were obtained. Using the complex hyperbolic secant pulses it was also possible to create two groups of ions, absorbing at specific frequencies, where 85% of the ions at one of the frequencies was shifted out of resonance with the field when ions in the other frequency group were excited. This procedure of selecting interacting ions, called qubit distillation, was carried out in preparation for two-qubit gate operations in the rare-earth-metal-ion-doped crystals. The techniques for frequency-selective state-to-state transfer developed here may be also useful also for other quantum optics and quantum information experiments in these long-coherence-time solid

  14. Biosorption of metal and salt tolerant microbial isolates from a former uranium mining area. Their impact on changes in rare earth element patterns in acid mine drainage.

    Science.gov (United States)

    Haferburg, Götz; Merten, Dirk; Büchel, Georg; Kothe, Erika

    2007-12-01

    The concentration of metals in microbial habitats influenced by mining operations can reach enormous values. Worldwide, much emphasis is placed on the research of resistance and biosorptive capacities of microorganisms suitable for bioremediation purposes. Using a collection of isolates from a former uranium mining area in Eastern Thuringia, Germany, this study presents three Gram-positive bacterial strains with distinct metal tolerances. These strains were identified as members of the genera Bacillus, Micrococcus and Streptomyces. Acid mine drainage (AMD) originating from the same mining area is characterized by high metal concentrations of a broad range of elements and a very low pH. AMD was analyzed and used as incubation solution. The sorption of rare earth elements (REE), aluminum, cobalt, copper, manganese, nickel, strontium, and uranium through selected strains was studied during a time course of four weeks. Biosorption was investigated after one hour, one week and four weeks by analyzing the concentrations of metals in supernatant and biomass. Additionally, dead biomass was investigated after four weeks of incubation. The maximum of metal removal was reached after one week. Up to 80% of both Al and Cu, and more than 60% of U was shown to be removed from the solution. High concentrations of metals could be bound to the biomass, as for example 2.2 mg/g U. The strains could survive four weeks of incubation. Distinct and different patterns of rare earth elements of the inoculated and non-inoculated AMD water were observed. Changes in REE patterns hint at different binding types of heavy metals regarding incubation time and metabolic activity of the cells. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Interaction of intermetallic compounds formed by rare earths, scandium, yttrium and 3d-transition metals, with gaseous ammonia

    International Nuclear Information System (INIS)

    Shilkin, S.P.; Volkova, L.S.

    1992-01-01

    Interaction of the RT n intermetallic compounds, where R Sc, Y, rare earths, T = Fe, Co, Ni; n = 2,3,5, with gaseous ammonia under pressure of 1MPa and at temperatures of 293, 723 and 798 K is studied. It is established on the basis of roentgenographic studied, chemical analysis data, X-ray photoelectron spectroscopy and specific surface measurements that metallic matrixes of intermetallides decompose into nitrides and transition metal phases at temperatures of 723 and 798 K under effect of ammonia and independent of structural types of the source materials; partial or complete decomposition of intermetallides through ammonia with formation of transition metal mixture, binary hydrides and nitrides of the most electropositive metal the above systems occurs at the temperature of 293 K depending on the heat of the source compounds and their tendency to decomposition under ammonia effect

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-19

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

  17. Rare earth-iron-boron premanent magnets

    International Nuclear Information System (INIS)

    Ghendehari, M.H.

    1988-01-01

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

  18. 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.

  19. Structure and electronic properties of ordered binay thin-film compounds of rare earths with transition metals

    International Nuclear Information System (INIS)

    Schneider, W.

    2004-01-01

    The present thesis deals with preparation of structurally ordered thin-film compounds of the rare-earths Ce and Dy with the transition metals Pd, Rh, and Ni as well as with investigations of their crystalline and electronic structures. Typically 10 nm-thick films were grown in-situ by deposition of the rare-earth metals onto single crystalline transitionmetal substrates or alternatively by codeposition of both constituents onto a W(110) single crystal. In both cases deposition was followed by short-term annealing at temperatures of 400-1000 C to achieve crystalline order. The latter was analyzed by means of low-energy electron-diffraction (LEED) and evaluated on the basis of a simple kinematic theory. The electronic structure was investigated by means of angle-resolved photoemission (ARPES), partially exploiting synchrotron radiation from BESSY. The studies concentrate mainly on the behavior of the valence bands as a function of structure and composition of the thin films, particularly under consideration of surface phenomena. Measured energy dispersions were compared with results of LDA-LCAO calculations performed in the framework of this thesis. Observed shifts of the energy bands by up to 1 eV are attributed in the light of a simple model to incomplete screening of the photoemission final states. (orig.)

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

    Directory of Open Access Journals (Sweden)

    M. G. Mahmoud

    2017-01-01

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

  1. Rare earth mobility in hydrothermal ore-forming systems

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  2. Use of EDTA for potentiometric back titration of rare earths and analysis of their mixtures

    International Nuclear Information System (INIS)

    Zayed, M.A.; Rizk, M.S.; Khalifa, H.; Omer, W.F.

    1987-01-01

    Advantage was taken of the stoichiometric reaction between mercury(II), rare earths, alkaline earths, heavy metal ions and EDTA in urotropine buffered media to determine rare earths by back-titration of excess EDTA in the course of estimating a variety of lanthanides or analysing their binary mixture with one of the alkaline earth metals by selective control of pH; or analysing their binary mixtures with heavy metals using fluoride as a good masking agent for rare earths; or analysing their ternary mixtures with both heavy and alkaline earth metals in two steps, one by selective control of pH and the other by masking of rare earths with fluoride at lower pH to estimate the heavy metal. The procedures given are simple, rapid and extremely reliable. 19 refs. (author)

  3. Byproduct metals and rare-earth elements used in the production of light-emitting diodes—Overview of principal sources of supply and material requirements for selected markets

    Science.gov (United States)

    Wilburn, David R.

    2012-01-01

    The use of light-emitting diodes (LEDs) is expanding because of environmental issues and the efficiency and cost savings achieved compared with use of traditional incandescent lighting. The longer life and reduced power consumption of some LEDs have led to annual energy savings, reduced maintenance costs, and lower emissions of carbon dioxide, sulfur dioxide, and nitrogen oxides from powerplants because of the resulting decrease in energy consumption required for lighting applications when LEDs are used to replace less-energy-efficient sources. Metals such as arsenic, gallium, indium, and the rare-earth elements (REEs) cerium, europium, gadolinium, lanthanum, terbium, and yttrium are important mineral materials used in LED semiconductor technology. Most of the world's supply of these materials is produced as byproducts from the production of aluminum, copper, lead, and zinc. Most of the rare earths required for LED production in 2011 came from China, and most LED production facilities were located in Asia. The LED manufacturing process is complex and is undergoing much change with the growth of the industry and the changes in demand patterns of associated commodities. In many respects, the continued growth of the LED industry, particularly in the general lighting sector, is tied to its ability to increase LED efficiency and color uniformity while decreasing the costs of producing, purchasing, and operating LEDs. Research is supported by governments of China, the European Union, Japan, the Republic of Korea, and the United States. Because of the volume of ongoing research in this sector, it is likely that the material requirements of future LEDs may be quite different than LEDs currently (2011) in use as industry attempts to cut costs by reducing material requirements of expensive heavy rare-earth phosphors and increasing the sizes of wafers for economies of scale. Improved LED performance will allow customers to reduce the number of LEDs in automotive, electronic

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

    Science.gov (United States)

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

    2015-11-01

    The mining of material resources requires knowledge about geogenic and anthropogenic deposits, in particular on the location of the deposits with the comparatively highest concentration of raw materials. In this study, we develop a framework that allows the establishment of analogies between geological and anthropogenic processes. These analogies were applied to three selected products containing rare earth elements (REE) in order to identify the most concentrated deposits in the anthropogenic cycle. The three identified anthropogenic deposits were characterised according to criteria such as "host rock", "REE mineralisation" and "age of mineralisation", i.e. regarding their "geological" setting. The results of this characterisation demonstrated that anthropogenic deposits have both a higher concentration of REE and a longer mine life than the evaluated geogenic deposit (Mount Weld, Australia). The results were further evaluated by comparison with the geological knowledge category of the United Nations Framework Classification for Fossil Energy and Mineral Reserves and Resources 2009 (UNFC-2009) to determine the confidence level in the deposit quantities. The application of our approach to the three selected cases shows a potential for recovery of REE in anthropogenic deposits; however, further exploration of both potential and limitations is required. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Rare Earth Polyoxometalates.

    Science.gov (United States)

    Boskovic, Colette

    2017-09-19

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

  6. High coercivity, anisotropic, heavy rare earth-free Nd-Fe-B by Flash Spark Plasma Sintering.

    Science.gov (United States)

    Castle, Elinor; Sheridan, Richard; Zhou, Wei; Grasso, Salvatore; Walton, Allan; Reece, Michael J

    2017-09-11

    In the drive to reduce the critical Heavy Rare Earth (HRE) content of magnets for green technologies, HRE-free Nd-Fe-B has become an attractive option. HRE is added to Nd-Fe-B to enhance the high temperature performance of the magnets. To produce similar high temperature properties without HRE, a crystallographically textured nanoscale grain structure is ideal; and this conventionally requires expensive "die upset" processing routes. Here, a Flash Spark Plasma Sintering (FSPS) process has been applied to a Dy-free Nd 30.0 Fe 61.8 Co 5.8 Ga 0.6 Al 0.1 B 0.9 melt spun powder (MQU-F, neo Magnequench). Rapid sinter-forging of a green compact to near theoretical density was achieved during the 10 s process, and therefore represents a quick and efficient means of producing die-upset Nd-Fe-B material. The microstructure of the FSPS samples was investigated by SEM and TEM imaging, and the observations were used to guide the optimisation of the process. The most optimal sample is compared directly to commercially die-upset forged (MQIII-F) material made from the same MQU-F powder. It is shown that the grain size of the FSPS material is halved in comparison to the MQIII-F material, leading to a 14% increase in coercivity (1438 kA m -1 ) and matched remanence (1.16 T) giving a BH max of 230 kJ m -3 .

  7. The origin of secondary heavy rare earth element enrichment in carbonatites: Constraints from the evolution of the Huanglongpu district, China

    Science.gov (United States)

    Smith, M.; Kynicky, J.; Xu, Cheng; Song, Wenlei; Spratt, J.; Jeffries, T.; Brtnicky, M.; Kopriva, A.; Cangelosi, D.

    2018-05-01

    The silico‑carbonatite dykes of the Huanglongpu area, Lesser Qinling, China, are unusual in that they are quartz-bearing, Mo-mineralised and enriched in the heavy rare earth elements (HREE) relative to typical carbonatites. The textures of REE minerals indicate crystallisation of monazite-(Ce), bastnäsite-(Ce), parisite-(Ce) and aeschynite-(Ce) as magmatic phases. Burbankite was also potentially an early crystallising phase. Monazite-(Ce) was subsequently altered to produce a second generation of apatite, which was in turn replaced and overgrown by britholite-(Ce), accompanied by the formation of allanite-(Ce). Bastnäsite and parisite where replaced by synchysite-(Ce) and röntgenite-(Ce). Aeschynite-(Ce) was altered to uranopyrochlore and then pyrochlore with uraninite inclusions. The mineralogical evolution reflects the evolution from magmatic carbonatite, to more silica-rich conditions during early hydrothermal processes, to fully hydrothermal conditions accompanied by the formation of sulphate minerals. Each alteration stage resulted in the preferential leaching of the LREE and enrichment in the HREE. Mass balance considerations indicate hydrothermal fluids must have contributed HREE to the mineralisation. The evolution of the fluorcarbonate mineral assemblage requires an increase in aCa2+ and aCO32- in the metasomatic fluid (where a is activity), and breakdown of HREE-enriched calcite may have been the HREE source. Leaching in the presence of strong, LREE-selective ligands (Cl-) may account for the depletion in late stage minerals in the LREE, but cannot account for subsequent preferential HREE addition. Fluid inclusion data indicate the presence of sulphate-rich brines during alteration, and hence sulphate complexation may have been important for preferential HREE transport. Alongside HREE-enriched magmatic sources, and enrichment during magmatic processes, late stage alteration with non-LREE-selective ligands may be critical in forming HREE

  8. Thermodynamic studies on the interaction between some amino acids with some rare earth metal ions in aqueous solutions

    International Nuclear Information System (INIS)

    Mohamed, AbdAllah A.; Bakr, Moustafa F.; Abd El-Fattah, Khaled A.

    2003-01-01

    The interactions between the amino acids (glycine and L-threonine) with some rare earth metal ions (Pr 3+ , Nd 3+ , Eu 3+ , Gd 3+ , Dy 3+ , Ho 3+ and Yb 3+ ) were studied at a wide range from ionic strengths (0.07-0.32 M KNO 3 ) and temperatures (25-45 deg. C) in aqueous solutions by using Bjerrum potentiometric method. The stoichiometric and thermodynamic stability constants were calculated as well as the standard thermodynamic parameters (ΔG deg., ΔH deg. and ΔS deg. ) for all possible reactions that occur. The degree of formation (n-bar) for all studied systems was determined and discussed. The thermodynamic parameters differences (ΔΔG deg., ΔΔH deg. and ΔΔS deg. ) were calculated and discussed to determine the factors which control these complexation processes from the thermodynamic point of view

  9. Study of interaction of uranium, plutonium and rare earth fluorides with some metal oxides in fluoric salt melts

    International Nuclear Information System (INIS)

    Gorbunov, V.F.; Novoselov, G.P.; Ulanov, S.A.

    1976-01-01

    Interaction of plutonium, uranium, and rare-earth elements (REE) fluorides with aluminium and calcium oxides in melts of eutectic mixture LiF-NaF has been studied at 800 deg C by X-ray diffraction method. It has been shown that tetravalent uranium and plutonium are coprecipitated by oxides as a solid solution UO 2 -PuO 2 . Trivalent plutonium in fluorides melts in not precipitated in the presence of tetravalent uranium which can be used for their separation. REE are precipitated from a salt melt by calcium oxide and are not precipitated by aluminium oxide. Thus, aluminium oxide in a selective precipitator for uranium and plutonium in presence of REE. Addition of aluminium fluoride retains trivalent plutonium and REE in a salt melt in presence of Ca and Al oxides. The mechanism of interacting plutonium and REE trifluorides with metal oxides in fluoride melts has been considered

  10. Rare earth metals. Production, use and recycling; Seltene Erdmetalle. Gewinnung, Verwendung und Recycling

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Bernhard; Mueller, Ralf

    2014-07-01

    In 1964, the nitrogen chemical plant in Piesteritz near Wittenberg opened to produce rare earth elements (REE), however only five of them were used in industry and technology. The predominant rest was placed in storage. Today, 50 years later, the five REE are starting to become a scarce commodity while the others are in stable demand. The reason for the sudden REE boom is a result of their unique optical and magnetic properties, which derive from their electron configuration of the 4f-orbitals. New applications for REE evolved in areas which nobody considered (or ''would have considered/thought about'') 50 years ago. Some examples include power generation in wind energy plants, high density information transfer in fibre optics or medical diagnoses by magnetic resonance tomography. Furthermore, common mobile electrical drive engineering would not be reasonable without REE. The electric vehicles of the future rely on REE for their La and Nd containing NiMH accumulators. The book at hand focuses on all common and emerging applications, the physical and chemical principles are also shown and discussed. The detailed knowledge of these principles is essential in order to create new approaches which allow for the substitution of REE and, where this is not possible, to establish concepts for economical consumption or recycling. With escalating scarcity of the REE this will be of increasing importance on the agenda of science and technology. Thus, recycling methods and concepts are the second focus of this book. The central goal is the incorporation of all existing chemical procedures into the recycling of 'end of life' products. This involves methods from the primary production of the materials up to the conservation of residual materials at the point of manufacturing. Several case examples are described to emphasize that the feasibility of this idea requires organized collecting systems and disassembly of the scrap electronic devices. A

  11. Analysis Of Corrosion Resistant Film On AI-Mg-Si Coated By Rare Earth Metal

    International Nuclear Information System (INIS)

    Darajati, Rusdiana; Ihsan, Mohammad; Wuryanto

    2001-01-01

    Corrosion analysis of AI-Mg-Si alloy which given corrosion-resistant film of a rare earth oxide coating incorporated with a uniform aluminum oxide film which has been formed on the aluminum alloy surface has been done. The measurement techniques were E corr versus time, polarization resistance, potentiodynamic and SEM (Scanning Electron Microscope for surface analysis. Potential corrosion in water environment tend to bigger with more time for four samples except sample AIMgSi that dipped into triethanolamine. ln HCl pH=1 potential corrosion sample AIMgSi, AIMgSi that dipped into triethanolamine, AIMgSi that dipped into triethanolamine and Ce Cl) tend to bigger with more time while sample AIMgSi that dipped into triethanolamine and YCI 3 or RECI 3 tend to smaller with more time. Potential corrosion in NaOH pH= 13 tend to bigger with more time for all samples. Corrosion rate for sample AIMgSi that dipped into triethanolamine in water environment relatively slower (0,0205 mpy), while in HCl pH=1 and NaOH pH=13 corrosion rate sample AIMgSi that dipped into triethanolamine and YCI 3 relatively slower, respectively are 0,1157 mpy and 2468,26 mpy. Sample AIMgSi that dipped into triethanolamine and RECI 3 in water environment has passivation and trans passivation area while four simple don't have passivation area, in H CI pH=1 all samples generally have passivation area at the same current density range while in NaOH pH= 13 sample AIMgSi has trans passivation area at a potential of about 800 mV while four other sample have passivation area at a potential of about-850-1500 mV. SEM analysis show that the coating layer which formed on the sample surface less protective especially in HCl pH= land NaOH pH=13

  12. 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

  13. Kinetical analysis of the heat treatment procedure in SmCo5 and other rare-earth transition-metal sintered magnets

    International Nuclear Information System (INIS)

    Campos, Marcos Flavio de; Rangel Rios, Paulo

    2004-01-01

    In the processing of all types of commercial sintered rare-earth transition-metal magnets (SmCo 5 , Sm(CoCuFeZr) z , NdFeB) a post-sintering heat treatment is included, which is responsible for large increase of the coercive field. During this post-sintering heat treatment, there are phase transformations with diffusion of the alloying elements, moving the system towards the thermodynamic equilibrium. Due to the larger size of the rare-earth atoms, the diffusion of the rare-earth atoms in the lattice of rare-earth transition-metal phases like SmCo 5 , Sm 2 (Co, Fe) 17 or Nd 2 Fe 14 B should be very slow, implying that the diffusion of the rare-earth atoms should be controlling the overall kinetics of the process. From the previous assumption, a parameter named 'diffusion length of rare-earth atoms' is introduced as a tool to study the kinetics of the heat treatment in rare-earth magnets. Detailed microstructural characterization of SmCo 5 and NdFeB magnets did not indicate significant microstructural changes between sintering and heat treatment temperatures and it was suggested that the increase of coercivity can be related to decrease of the content of lattice defects. The sintering temperature is high, close to melting temperature, and in this condition there are large amount of defects in the lattice, possibly rare-earth solute atoms. Phase diagram analysis has suggested that a possible process for the coercivity increase can be the elimination of excess rare-earth atoms, i.e. solute atoms from a supersatured matrix. The 'diffusion length of rare-earth atoms' estimated from diffusion kinetics is compatible with the diffusion length determined from microstructure. For the case of SmCo 5 , it was found that the time of heat treatment necessary is around 20 times lower if an isothermal treatment at 850 deg. C is substituted by a slow cooling from sintering temperature 1150 to 850 deg. C. These results give support for the thesis that the coercivity increase is

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

    International Nuclear Information System (INIS)

    Seon, F.; Barthole, G.

    1986-01-01

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

  15. Ortho-para-conversion of hydrogen in films of rare earth metals

    International Nuclear Information System (INIS)

    Zhavoronkova, K.N.; Peshkov, A.V.

    1979-01-01

    Investigated is specific catalytic activity of REE to clarify to what an extent the change of electron structure of the metals might influence their catalytic properties. Conducted is investigation of Sc, It, La and other lanthanides, except Eu amd Pm prepared in the form of metallic films, impowdered in vacuum of 10 -7 torr. It is established, that pape earth elements as catalysts of low-temperature ortho-para-conversion od hydrogen are divided into 2 groups, differing by mechanism of the reaction. Comparison of experimental results with the calculation results of absolute rates of paramagnetic conversion and also with investigation results of isotopjc exchange on these metals showed, that on the metals of group 1 conversjon proceeds according to chemical mechanism, and on the metals of group 2 - according to oscillating magnetic mechanism

  16. Coprecipitation of rare earths in systems of three heterovalent ions with sulfates of alkali and alkaline-earth metals

    International Nuclear Information System (INIS)

    Bobrik, V.M.

    1977-01-01

    Co-precipitation of rare earth elements (REE) in milligram amounts (3x10 -3 -3x10 -1 M) with alkali earth (AEE) sulfates in presence of alkali metal ions has been studied, the AEE:REE ratios between the co-precipitator and a REE (up to 50:1) the latter can be co-precipitated quantitatively in presence of corresponding alkali metals linked with the AEE in the Periodic table by a diagonal, i.e. in presence of sodium in co-precipitation with calcium sulfate, potassium with strontium sulfate and rubidium with barium sulfate. Co-precipitation with sulfates of sodium and calcium occurs at temperatures above 85 deg C and presumably involves calcium semihydrate. In presence of an alkali metal REE co-precipitation with AEE becomes isomorphic, i.e. at different AEE:REE ratios the co-precipitation coefficient remains constant. In presence of corresponding alkali metals the decrease in effectiveness of co-precipitation with AEE in the La-Lu series is more pronounced

  17. Rare earth - no case for government intervention

    OpenAIRE

    Georg Zachmann

    2010-01-01

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

  18. Physico-chemical characteristics and Heavy metal levels in Drinking ...

    African Journals Online (AJOL)

    Physico-chemical characteristics and Heavy metal levels in Drinking Water ... composition was analysed using X-ray Fluorescence spectroscopy. Majority of the water samples had neutral pH (6.80 – 7.20) few were slightly alkaline and one was acidic. ... Heavy metals (copper and lead), rare earth metals (gallium, rubidium, ...

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    The surface energy shifts of the occupied and unoccupied 4f levels for the lanthanide metals have been calculated from first principles by means of a Green’s-function technique within the tight-binding linear muffin-tin orbitals method. We use the concept of complete screening to identify...... the occupied and unoccupied 4f energy level shifts as the surface segregation energy of a 4fn-1 and 4fn+1 impurity atom, respectively, in a 4fn host metal. The calculations include both initial- and final-state effects and give values that are considerably lower than those measured on polycrystalline samples...... as well as those found in previous initial-state model calculations. The present theory agrees well with very recent high-resolution, single-crystal film measurements for Gd, Tb, Dy, Ho, Er, Tm, and Lu. We furthermore utilize the unique possibility offered by the lanthanide metals to clarify the roles...

  20. Metal, trace and rare earth element assessment in a sedimentary profile from Itupararanga Reservoir, São Paulo State, Brazil, by NAA

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sharlleny A.; Henrique, Heloise A.R., E-mail: shasilva@sp.gov.br [Companhia Ambiental do Estado de São Paulo (ELAI/CETESB), São Paulo, SP (Brazil). Setor de Química Inorgânica; Fávaro, Déborah I.T., E-mail: defavaro@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    In the present study the preliminary results for 2 sediment cores from the Itupararanga Reservoir are presented. Instrumental neutron activation analysis was also applied to the sediment samples to determine the total concentration of some metal, trace and rare earth elements. The results obtained were compared to the reference values NASC (North American Shale Composite). The enrichment factor (EF) was applied to the results obtained by using NASC (North American Shale Composite) and the concentration values of the last layer of this profile as reference values for sediment contamination index assessment. The EF calculated with the NASC values presented enrichment for As, Ce, Fe, La, Th and U in the two profiles Nd, Sm Hf and Tb, only present enrichment in the 2{sup nd} campaign. However, with respect to the base of the profile there was no element with enrichment. For semi metal As and for metals Cr and Zn the concentration values were compared to the oriented values from Environmental Canada (TEL and PEL). As and Cr presented values between TEL and PEL and Zn, values below TEL. The distribution pattern of light and heavy REEs was also verified in relation to the normatization of PAAS (Pos Archean Australian Shale). (author)

  1. Synthesis of rare-earth metal amides bearing an imidazolidine-bridged bis(phenolato) ligand and their application in the polymerization of L-lactide.

    Science.gov (United States)

    Zhang, Zhongjian; Xu, Xiaoping; Li, Wenyi; Yao, Yingming; Zhang, Yong; Shen, Qi; Luo, Yunjie

    2009-07-06

    A series of neutral rare-earth metal amides supported by an imidazolidine-bridged bis(phenolato) ligand were synthesized, and their catalytic activity for the polymerization of l-lactide was explored. The amine elimination reactions of Ln[N(TMS)(2)](3)(mu-Cl)Li(THF)(3) with H(2)[ONNO] {H(2)[ONNO] = 1,4-bis(2-hydroxy-3,5-di-tert-butyl-benzyl)-imidazolidine} in a 1:1 molar ratio in tetrahydrofuran (THF) gave the neutral rare-earth metal amides [ONNO]Ln[N(TMS)(2)](THF) [Ln = La (1), Pr (2), Nd (3), Sm (4), Yb (5), and Y (6)] in high isolated yields. All of these complexes are fully characterized. X-ray structural determination revealed that complexes 1-6 are isostructural and have a solvated monomeric structure. The coordination geometry around each of the rare-earth metal atoms can be best described as a distorted trigonal bipyramid. It was found that complexes 1-6 are efficient initiators for the ring-opening polymerization of l-lactide, and the ionic radii of the central metals have a significant effect on the catalytic activity. A further study revealed that these rare-earth metal amides can initiate l-lactide polymerization in a controlled manner in the presence of 1 equiv of isopropyl alcohol.

  2. Rare-earth elements

    Science.gov (United States)

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

    2017-12-19

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

  3. Structural studies of Langmuir-Blodgett films containing rare-earth metal cations

    DEFF Research Database (Denmark)

    Khomutov, G.B.; Antipina, M.N.; Bykov, I.V.

    2002-01-01

    Comparative structural study of gadolinium stearate Langmuir-Blodgett (LB) films formed by monolayer deposition from either aqueous gadolinium acetate or gadolinium chloride solutions have been carried out. Structure of the films was characterized by X-ray diffraction, Fourier transform infrared...... spectroscopy, high-energy electron diffraction, atomic force microscopy and scanning electron microscopy. It was found that when subphase pH had a value at which all monolayer stearic acid molecules were ionized and bound with Gd3+ cations (pH > 5), the LB films deposited from gadolinium acetate and gadolinium....... The data obtained indicate that the control of multivalent metal cations complexes formation in the subphase and at the monolayer surface can be an instrument for optimization, the conditions to form metal-containing LB film with regulated structure and properties....

  4. New ternary transition metal borides containing uranium and rare earth elements

    International Nuclear Information System (INIS)

    Rogl, P.; Delong, L.

    1983-01-01

    The new ternary actinide metal diborides U 2 MoB 6 , U 2 ReB 6 , U 2 OsB 6 , URuB 4 and UOsB 4 were prepared and found to crystallize with either the Y 2 ReB 6 or the ThMoB 4 type of structure. LuRuB 4 and LuOsB 4 crystallize with the YCrB 4 type of structure. In a ternary series of solid solutions YRh 3 Bsub(1-x) (0 0 C), boron was found to stabilize a Cu 3 Au type of structure. The superconductivity of the new uranium compounds and of a series of ternary transition metal borides was investigated; no superconductivity was observed for temperatures as low at 1.3-1.5 K. The cubic perovskite or filled Cu 3 Au structure is discussed as a type which is very unfavorable for the occurrence of superconductivity. (Auth.)

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

    Science.gov (United States)

    Aldén, M.; Johansson, B.; Skriver, H. L.

    1995-02-01

    The surface energy shifts of the occupied and unoccupied 4f levels for the lanthanide metals have been calculated from first principles by means of a Green's-function technique within the tight-binding linear muffin-tin orbitals method. We use the concept of complete screening to identify the occupied and unoccupied 4f energy level shifts as the surface segregation energy of a 4fn-1 and 4fn+1 impurity atom, respectively, in a 4fn host metal. The calculations include both initial- and final-state effects and give values that are considerably lower than those measured on polycrystalline samples as well as those found in previous initial-state model calculations. The present theory agrees well with very recent high-resolution, single-crystal film measurements for Gd, Tb, Dy, Ho, Er, Tm, and Lu. We furthermore utilize the unique possibility offered by the lanthanide metals to clarify the roles played by the initial and the different final states of the core-excitation process, permitted by the fact that the so-called initial-state effect is identical upon 4f removal and 4f addition. Surface energy and work function calculations are also reported.

  6. Effects of Rare Earth Metal addition on the cavitation erosion-corrosion resistance of super duplex stainless steels

    Science.gov (United States)

    Shim, Sung-Ik; Park, Yong-Soo; Kim, Soon-Tae; Song, Chi-Bok

    2002-05-01

    Austenitic stainless steels such as AISI 316L have been used in equipment in which fluid flows at high speeds which can induce cavitation erosion on metallic surfaces due to the collapse of cavities, where the collapse is caused by the sudden change of local pressure within the liquid. Usually AISI 316L is susceptible to cavitation erosion. This research focuses on developing a better material to replace the AISI 316L used in equipment with high speed fluid flow, such as impellers. The effects of Rare Earth Metal (REM) additions on the cavitation erosion-corrosion resistance of duplex stainless steels were studied using metallographic examination, the potentiodynamic anodic polarization test, the tensile test, the X-ray diffraction test and the ultrasonic cavitation erosion test. The experimental alloys were found to have superior mechanical properties due to interstitial solid solution strengthening, by adding high nitrogen (0.4%), as well as by the refinement of phases and grains induced by fine REM oxides and oxy-sulfides. Corrosion resistance decreases in a gentle gradient as the REM content increases. However, REM containing alloys show superior corrosion resistance compared with that of other commercial alloys (SAF 2507, AISI 316L). Owing to their excellent mechanical properties and corrosion resistance, the alloys containing REM have high cavitation erosion-corrosion resistance.

  7. Evaluation of the effect of heavy rare earth elements on the microstructure and mechanical and electrical properties of zirconia - Yttria ceramics

    International Nuclear Information System (INIS)

    Lazar, Dolores Ribeiro Ricci

    2002-01-01

    The use of Yttria concentrates for synthesis and processing of zirconia based ceramics, applied as structural and solid electrolyte materials, was investigated in this work. Terbium, dysprosium, holmium, erbium and ytterbium are chemical elements, classified as heavy rare earths, that can be found in those concentrates due to their association with yttrium ores. The ceramic characteristics were compared to zirconia - Yttria and zirconia - Yttria - rare earth oxide systems. The dopant content was 3 and 9 mol%. The raw materials were prepared by the coprecipitation route using solutions from the chemical processing of zircon and monazite ores and obtained by dissolution of high purity rare earth oxides. In the first part of this work, calcination, milling and ceramic processing were studied to produce ceramics with densities up to 95% TD. Samples were prepared in optimized conditions for the evaluation of the effect of each heavy rare earth element. Powders were characterized by chemical analysis. X-ray diffraction, scanning and transmission electron microscopy, gas adsorption (BET) and laser diffraction for the determination of the agglomerate size distributions. Green pellets were characterized by mercury porosimetry and the sintering kinetic was studied by dilatometry. The characterization of the as-sintered pellets was performed by the apparent density measurement (Archimedes method). X-ray diffraction, microstructure analysis by scanning and transmission electron microscopy, Vickers indentation tests for hardness and fracture toughness determination, dynamic mechanical analysis for the elastic modulus measurement, and impedance spectroscopy for electrical resistivity measurement. It was observed that the presence of heavy rare earths in a concentrate containing 85 wt% of Yttria has no significant influence on the properties of zirconia based ceramics. TZP ceramics, containing 3 mol% of dopants, have grain size smaller than 0.4μm, and Vickers hardness and

  8. Rare earth octacyanomolybdates(4)

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  9. 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...

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

    International Nuclear Information System (INIS)

    Ferreira, Eliner Affonso

    2013-01-01

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

  11. Rare-earth metal compounds with a novel ligand 2-methoxycinnamylidenepyruvate: A thermal and spectroscopic approach

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, C.T., E-mail: claudiocarvalho@ufgd.edu.br [Federal University of Grande Dourados, UFGD, 79.804-970 Dourados, MS (Brazil); Oliveira, G.F. [Federal University of Grande Dourados, UFGD, 79.804-970 Dourados, MS (Brazil); Fernandes, J. [Federal University of Grande Dourados, UFGD, 79.804-970 Dourados, MS (Brazil); Federal University of Mato Grosso, UFMT, 78.060-900 Cuiabá, MT (Brazil); Federal University of Goiás, UFG, 74.690-900, Goiânia, GO (Brazil); Institute of Chemistry, UNESP, 14.801-970 Araraquara, SP (Brazil); Siqueira, A.B. [Federal University of Mato Grosso, UFMT, 78.060-900 Cuiabá, MT (Brazil); Ionashiro, E.Y. [Federal University of Goiás, UFG, 74.690-900, Goiânia, GO (Brazil); Ionashiro, M. [Institute of Chemistry, UNESP, 14.801-970 Araraquara, SP (Brazil)

    2016-08-10

    Highlights: • 2-Methoxycinnamylidenepyruvate as a novel ligand for the synthesis of complexes. • Complexes with well-defined structural arrangements. • Thermal decomposition dependent on the nature of the metal ion. • Study by TG/FT-IR and TG/MS of the gaseous products released. • Potential technological application. - Abstract: Compounds of 2-methoxycinnamylidenepyruvate with trivalent lanthanide ions (Tb, Ho, Er, Tm, Yb and Lu) were obtained in solid state and studied mainly in terms of their thermal and spectroscopic properties. The analyses of the characterization were performed by thermogravimetric system coupled to a mass and infrared spectrometer (TG–DTA/MS and TG–DTA/FT-IR), X-ray powder diffractometry, differential scanning calorimetry (DSC), infrared (FT-IR), preliminary study of fluorescence as well as classical technique of titration with EDTA. From these results, it was possible to establish the stoichiometry, thermal behavior, hydration water content, and the gaseous products released in the thermal decomposition steps, and suggest the type of metal-ligand coordination.

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

    International Nuclear Information System (INIS)

    Sadikin, Yolanda; Stare, Katarina; Schouwink, Pascal; Brix Ley, Morten; Jensen, Torben R.; Meden, Anton; Černý, Radovan

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-15

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

  14. 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.

  15. Fabrication of self supporting metallic rare earth targets using a piezo-electric quartz as substrate

    International Nuclear Information System (INIS)

    Bonetti, C.P.

    1975-01-01

    Metallic self-supporting targets of cerium and praseodymium of 1 to 2.5mg/cm 2 on a diameter of 18mm were made using the process of evaporation by electron bombardment. Materials are placed on a piezo-electric quartz which permits the direct and precise measurement of the mass of the deposit. Then, such a deposit must be removed and placed on a frame in an environment of argon gas. This method is important because it can be used for small quantities of materials (case of separated isotopes). These high purity foils are used for the study of (d,n) reactions with the Tandem Van de Graaff Accelerator [fr

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

    International Nuclear Information System (INIS)

    Casini, Julio Cesar Serafim

    2011-01-01

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

  17. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

    Science.gov (United States)

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-01

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

  18. Several new phases in RE-Mg-Ge systems (RE = rare earth metal) - syntheses, structures, and chemical bonding

    International Nuclear Information System (INIS)

    Suen, Nian-Tzu; Bobev, Svilen

    2012-01-01

    Reported are the synthesis and structural characterization of Ce_5Mg_8Ge_8 (its own structure type), CeMg_2_-_xGe_2_+_x (BaAl_4-type structure), RE_4Mg_7Ge_6 (RE = Ce-Nd, Sm; La_4Mg_7Ge_6-type structure), and RE_4Mg_5Ge_6 (RE = Ce, Pr; Tm_4Zn_5Ge_6-type structure). The structures of these compounds have been established by single-crystal and powder X-ray diffraction. These compounds are closely related to each other not only in their chemical compositions but also in their structures. A common structural feature of all are MgGe_4 tetrahedra, which are connected by corner- and/or edge-sharing into complex polyanionic frameworks with the rare-earth metal atoms filling the ''empty'' space. The structures are compared to known types of structures, and we have investigated the chemical bonding in Ce_5Mg_8Ge_8 with electronic structure calculations, which were carried out by the tight-bonding linear muffin-tin orbital (TB-LMTO) method. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Directory of Open Access Journals (Sweden)

    M. G. Mahmoud

    2017-01-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

  1. Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with β-diketones

    International Nuclear Information System (INIS)

    Imura, H.; Ebisawa, M.; Kato, M.; Ohashi, K.

    2006-01-01

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

  2. Isostructural crystal hydrates of rare-earth metal oxalates at high pressure. From strain anisotropy to dehydration

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Boris A.; Matvienko, Alexander A. [Russian Academy of Ssciences, Novosibirsk (Russian Federation). Inst. of Solid State Chemistry and Mechanochemistry; Novosibirsk State Univ. (Russian Federation); Gribov, Pavel A.; Boldyreva, Elena V. [Russian Academy of Ssciences, Novosibirsk (Russian Federation). Inst. of Solid State Chemistry and Mechanochemistry

    2017-07-01

    The crystal structures of a series of isostructural rare-earth metal oxalates, (REE){sub 2}(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O (REE=Sm, Y) and a 1:1 YSm(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O solid solution, have been studied in situ by single-crystal X-ray diffraction and optical microscopy. The structures were followed from ambient pressure to 6 GPa in a DAC with paraffin as the hydrostatic fluid. Bulk compressibilities, anisotropic lattice strain on hydrostatic compression and the corresponding changes in the atomic coordinates were followed. Discontinuities/sharp changes in the slopes of the pressure dependences of volume and selected cell parameters have been observed for yttrium-containing salts at ∝3.5 GPa. This may be related to the re-distribution of water molecules within the crystal structure. Y{sub 2}(C{sub 2}O{sub 4}){sub 3}.10H{sub 2}O undergoes a partial dehydration at 1 GPa, forming monoclinic Y{sub 2}(C{sub 2}O{sub 4}){sub 3}.6H{sub 2}O as single-crystalline inclusions in the original phase.

  3. Deeply inelastic transfer reactions induced by heavy ions in rare earth targets. II. Interpretation of experimental data

    International Nuclear Information System (INIS)

    Rivet, M.F.; Bimbot, R.; Ngo, C.

    1979-01-01

    The experimental angular distributions and cross sections for a series of deeply inelastic transfer reactions induced by various projectiles in rare earth targets have been interpreted using a model which includes a dynamical coupling between relative motion and mass asymmetry and treats statistical fluctuations. As the transfer reactions considered correspond to an increase of the potential energy of the composite system their observation is mainly due to fluctuations. The calculation reproduces correctly the angular distributions, but the cross sections are underestimated. Several effects are discussed which may increase these cross sections and are neglected in the calculation

  4. Behavior of new complexes of tetrakis(4-methoxylphenyl)porphyrin with heavy rare earth elements in reversed-phase high performance liquid chromatography.

    Science.gov (United States)

    Zhang, Jun-Feng; Wang, Hong; Hou, An-Xin; Wang, Chang-Fa; Zhang, Hua-Shan

    2004-08-01

    An HPLC method has been developed for the separation of new complexes of tetrakis(4-methoxylphenyl)porphyrin (TMOPP) with four heavy rare earth elements (RE = Y, Er, Tm, and Yb). The function of amine and acid in the mobile phase has been investigated and a reasonable explanation is presented. Successful separation of the RE-TMOPP-Cl complexes is accomplished in 10 min with a mobile phase consisting of methanol-water-acetic acid-triethanolamine. The detection limits (S/N= 3) for the four complexes are 0.01 microg/mL. This method is rapid, sensitive, and simple.

  5. Rare earth element lithogeochemistry of granitoid mineral deposits

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, R.P.; Fryer, B.J. (Memorial Univ. of Newfoundland, St. John' s (Canada). Dept. of Earth Sciences)

    1983-12-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl/sup -/ complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F/sup -/ and CO/sub 3//sup 2 -/ become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl/sup -/ versus F/sup -/ versus CO/sub 3//sup 2 -/ in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F/sup -/ and CO/sub 3//sup 2 -/ in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution.

  6. Rare earth element lithogeochemistry of granitoid mineral deposits

    International Nuclear Information System (INIS)

    Taylor, R.P.; Fryer, B.J.

    1983-01-01

    As a monitor of the processes involved in the formation of granitoid mineral deposits the coherent group behaviour of the rare earth elements (REE) actively reflects changing fluid characteristics. For example, in the porphyry environment, magmatic-hydrothermal fluids produce potassic alteration with strong enrichment in the light rare earth elements, reflecting their high pH, low fluid/rock ratios, and the dominant role of Cl - complexing in metal (i.e. Cu, Au) transport. With increasing fluid/rock ratios and decreasing pH accompanying the progressive involvement of meteoric fluids (and the production of propylitic, argillic, and phyllic alteration) anionic species such as F - and CO 3 2- become important in metal (e.g. Mo, W) transport through complexing, and their activity in the hydrothermal fluids is illustrated by mobilization of the heavy rare earth elements. The relative involvement of Cl - versus F - versus CO 3 2- in metal transport in other granite-related systems can also be monitored through REE behaviour. Hence granitoid tin-tungsten mineralization and associated greisenization typically exhibit heavy rare earth enrichment and evidence the importance of F - and CO 3 2- in metal transport. Similarly, heavy rare earth element enrichment in hydrothermal uranium deposits can be related to the transport of uranium as carbonate complexes. REE are widely accepted as powerful tools in the study of rock petrogenesis, but their use has been neglected in the investigation of mineral deposits. The recognition of the systematic variation of REE distributions in granitoid mineral deposits suggests that the application of REE geochemistry, particularly when integrated with fluid inclusion and isotope studies, can provide l) an effective method for identifying the physiochemical controls of metal transport and 2) a useful criterion of elucidating metal distribution

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-15

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

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

    International Nuclear Information System (INIS)

    Morf, Leo S.; Gloor, Rolf; Haag, Olaf; Haupt, Melanie; Skutan, Stefan; Lorenzo, Fabian Di; Böni, Daniel

    2013-01-01

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

  9. Superconductivity in ternary rare earth transition metal silicides and germanides with the Sc5Co4Si10-type structure

    International Nuclear Information System (INIS)

    Berg, L.S.

    1986-01-01

    A systematic study of the superconducting and normal state properties of some ternary rare earth transition metal silicides and germanides of the Sc 5 Co 4 Si 10 0-type is reported. Low temperature heat capacity measurements indicate the presence of a complicated phonon density of states in these structurally complex compounds. A better description of the phonon spectrum of the high T/sub c/ materials Sc 5 Rh 4 Si 10 , Sc 5 Ir 4 Si 10 , and Y 5 Os 4 Ge 10 , given by a model proposed by Junod et al., is presented and discussed. The large values of ΔC/γ/sub n/T/sub c/ and the electron-phonon coupling constant for these high T/sub c/ compounds indicate that they are strong-coupled superconductors. Relative to other ternary superconductors, many of these materials have large Debye temperatures. DC electrical resistivity measurements on these compounds show resistivity behavior deviating from those exhibited by simple metals. The rho(T) data for Y 5 Ir 4 Si 10 , Lu 5 Ir 4 Si 10 , and Y 5 Os 4 Ge 10 , indicate the presence of anomalies. Static molar magnetic susceptibility measurements performed on these compounds indicate (1) a small effective magnetic moment of 0.26μ/sub B/ on the Co atom and (2) anomalous behaviors in the Lu 5 Rh 4 Si 10 , Lu 5 Ir 4 Si 10 , Y 5 Ir 4 Si 10 , Lu 5 Ir 4 Ge 10 , and Y 5 Rh 4 Ge 10 data. Lastly, upper critical magnetic field measurements were performed on Sc 5 Co 4 Si 10 , Sc 5 Rh 4 Si 10 , Sc 5 Ir 4 Si 10 , Lu 5 Rh 4 Si 10 , Lu 5 Ir 4 Si 10 , and Y 5 Os 4 Ge 10

  10. Rare earth germanates

    International Nuclear Information System (INIS)

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

    1983-01-01

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

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

    OpenAIRE

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

    2017-01-01

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

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

    International Nuclear Information System (INIS)

    Inagaki, Kenta; Ogata, Takanari

    2010-01-01

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

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

    International Nuclear Information System (INIS)

    Deodhar, S.S.

    1975-01-01

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

  14. 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

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

    International Nuclear Information System (INIS)

    Zhang, Yang

    2013-01-01

    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 x M 3-x N rate at C 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 13 C NMR spectroscopic studies demonstrated exceptional NMR behaviors that resulted from switching the second metal inside of the mixed metal nitride cluster Ho x M 3-x N from Sc to Lu and further to Y. The LnSc 2 N rate at C 80 (Ln= Ce, Pr, Nd, Tb, Dy, Ho, Lu) MMNCFs were characterized by 13 C and 45 Sc NMR study respectively. According to Bleaney's theory and Reilley method, the separation of δ PC and δ con from δ para was achieved by the primary 13 C and 45 Sc NMR analysis of LnSc 2 N rate at C 80 (I). The

  16. A Novel Synthesis Routine for Woodwardite and Its Affinity towards Light (La, Ce, Nd and Heavy (Gd and Y Rare Earth Elements

    Directory of Open Access Journals (Sweden)

    Sirio Consani

    2018-01-01

    Full Text Available A synthetic Cu-Al-SO4 layered double hydroxide (LDH, analogue to the mineral woodwardite [Cu1−xAlx(SO4x/2(OH2·nH2O], with x < 0.5 and n ≤ 3x/2, was synthesised by adding a solution of Cu and Al sulphates to a solution with NaOH. The pH values were kept constant at 8.0 and 10.0 by a continuous addition of NaOH. The material obtained had poor crystallinity, turbostratic structure, and consisted of nanoscopic crystallites. The analyses performed in order to characterise the obtained materials (X-ray diffraction (XRD, thermogravimetry (TG, and Fourier Transform Infra-Red (FTIR spectroscopy showed that the Cu-Al-SO4 LDH is very similar to woodwardite, although it has a smaller layer spacing, presumably due to a lesser water content than in natural samples. The synthesis was performed by adding light rare earth elements (LREEs (La, Ce, and Nd and heavy rare earth elements (HREEs (Gd and Y in order to test the affinity of the Cu-Al-SO4 LDH to the incorporation of REEs. The concentration of rare earth elements (REEs in the solid fraction was in the range of 3.5–8 wt %. The results showed a good affinity for HREE and Nd, especially for materials synthesised at pH 10.0, whereas the affinities for Ce and La were much lower or non-existent. The thermal decomposition of the REE-doped materials generates a mixture of Cu, Al, and REE oxides, making them interesting as precursors in REE oxide synthesis.

  17. Rare earth industry in India

    International Nuclear Information System (INIS)

    Singh, D.S.

    2016-01-01

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

  18. Enhancement in extraction rates by addition of organic acids to aqueous phase in solvent extraction of rare earth metals in presence of diethylenetriaminepentaacetic acid

    International Nuclear Information System (INIS)

    Matsuyama, Hideto; Azis, A.; Fujita, Mamoru; Teramoto, Masaaki.

    1996-01-01

    It is well known that the selectivity of rare earth metals by solvent extraction is increased by the addition of a chelating agent such as diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase. One of the disadvantages of this method is the decrease in extraction rates due to complexation in the aqueous phase. In this paper, further addition of organic acids to the aqueous phase was examined for the purpose of enhancing the extraction rates in solvent extraction with DTPA. The addition of several kind of organic acids such as formic acid, acetic acid, malonic acid, lactic acid and citric acid was investigated for a Er/Y separation system. A remarkable enhancement in extraction rates was observed with a slight decrease in the selectivity by the addition of citric acid or lactic acid. Extraction rates in the presence of both DTPA and citric acid increased with the increase in citric acid concentration and with the increase in proton concentration. A 150 times enhancement in extraction rates was found in the low proton concentration condition. In order to analyze the extraction rates and selectivities obtained, mass transfer equations were presented by considering both the dissociation reaction of rare earth metal-DTPA complexes and the complex formation between rare earth metal and organic acid in the aqueous phase. The experimental data were analyzed by these equations. (author)

  19. 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)

  20. Rare earth elements behavior in Peruibe black mud

    International Nuclear Information System (INIS)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2004-07-13

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Radu, I.E.

    2006-03-15

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  4. 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.

  5. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

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

  6. Rare earth metal bis(amide) complexes bearing amidinate ancillary ligands: synthesis, characterization, and performance as catalyst precursors for cis-1,4 selective polymerization of isoprene.

    Science.gov (United States)

    Luo, Yunjie; Fan, Shimin; Yang, Jianping; Fang, Jianghua; Xu, Ping

    2011-03-28

    A family of rare earth metal bis(amide) complexes bearing monoanionic amidinate [RC(N-2,6-Me(2)C(6)H(3))(2)](-) (R = cyclohexyl (Cy), phenyl (Ph)) as ancillary ligands were synthesized and characterized. One-pot salt metathesis reaction of anhydrous LnCl(3) with one equivalent of amidinate lithium [RC(N-2,6-Me(2)C(6)H(3))(2)]Li, following the introduction of two equivalents of NaN(SiMe(3))(2) in THF at room temperature afforded the neutral and unsolvated mono(amidinate) rare earth metal bis(amide) complexes [RC(N-2,6-Me(2)C(6)H(3))(2)]Y[N(SiMe(3))(2)](2) (R = Cy (1); R = Ph (2)), and the "ate" mono(amidinate) rare earth metal bis(amide) complex [CyC(N-2,6-Me(2)C(6)H(3))(2)]Lu[N(SiMe(3))(2)](2)(μ-Cl)Li(THF)(3) (3) in 61-72% isolated yields. These complexes were characterized by elemental analysis, NMR spectroscopy, FT-IR spectroscopy, and X-ray single crystal diffraction. Single crystal structural determination revealed that the central metal in complexes 1 and 2 adopts a distorted tetrahedral geometry, and in complex 3 forms a distorted trigonal bipyramidal geometry. In the presence of AlMe(3), and in combination with one equimolar amount of [Ph(3)C][B(C(6)F(5))(4)], complexes 1 and 2 showed high activity towards isoprene polymerization to give high molecular weight polyisoprene (M(n) > 10(4)) with good cis-1,4 selectivity (>90%).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1963-04-15

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

  8. Utility of Lithium in Rare-Earth Metal Reduction Reactions to Form Nontraditional Ln2+ Complexes and Unusual [Li(2.2.2-cryptand)]1+ Cations.

    Science.gov (United States)

    Huh, Daniel N; Darago, Lucy E; Ziller, Joseph W; Evans, William J

    2018-02-19

    The utility of lithium compared to other alkali metals in generating Ln 2+ rare-earth metal complexes via reduction of Ln 3+ precursors in reactions abbreviated as LnA 3 /M (Ln = rare-earth metal; A = anionic ligand; M = alkali metal) is described. Lithium reduction of Cp' 3 Ln (Cp' = C 5 H 4 SiMe 3 ; Ln = Y, Tb, Dy, Ho) under Ar in the presence of 2.2.2-cryptand (crypt) forms new examples of crystallographically characterizable Ln 2+ complexes of these metals, [Li(crypt)][Cp' 3 Ln]. In each complex, lithium is found in an N 2 O 4 donor atom coordination geometry that is unusual for the cryptand ligand. Magnetic susceptibility data on these new examples of nontraditional divalent lanthanide complexes are consistent with 4f n 5d 1 electronic configurations. The Dy and Ho complexes have exceptionally high single-ion magnetic moments, 11.35 and 11.67 μ B , respectively. Lithium reduction of Cp' 3 Y under N 2 at -35 °C forms the Y 2+ complex (Cp' 3 Y) 1- , which reduces dinitrogen upon warming to room temperature to generate the (N 2 ) 2- complex [Cp' 2 Y(THF)] 2 (μ-η 2 :η 2 -N 2 ). These results provide insight on the factors that lead to reduced dinitrogen complexes and/or stable divalent lanthanide complexes as a function of the specific reducing agent and conditions.

  9. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.C.

    1975-01-01

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

  10. 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."

  11. Rare earths refining by vacuum sublimation method

    International Nuclear Information System (INIS)

    Rytus, N.N.

    1983-01-01

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

  12. Synthesis and characterization of anionic rare-earth metal amides stabilized by phenoxy-amido ligands and their catalytic behavior for the polymerization of lactide.

    Science.gov (United States)

    Lu, Min; Yao, Yingming; Zhang, Yong; Shen, Qi

    2010-10-28

    A dianionic phenoxyamido ligand was the first to be used to stabilize organo-rare-earth metal amido complexes. Amine elimination reaction of Nd[N(TMS)(2)](3)(μ-Cl)Li(THF)(3) (TMS = SiMe(3)) with aminophenol [HNOH] {[HNOH] = N-p-methylphenyl(2-hydroxy-3,5-di-tert-butyl)benzylamine} in a 1 : 1 molar-ratio gave the anionic phenoxyamido neodymium amide [NO](2)Nd[N(TMS)(2)][Li(THF)](2) (2) in a low isolated yield. A further study revealed that the stoichiometric reactions of Ln[N(TMS)(2)](3)(μ-Cl)Li(THF)(3) with the lithium aminophenoxy [HNOLi(THF)](2) (1) in tetrahydrofuran (THF) gave the anionic rare-earth metal amido complexes [NO](2)Ln[N(TMS)(2)][Li(THF)](2) [Ln = Nd (2), Sm (3), Yb (4), Y (5)] in high isolated yields. All of these complexes are fully characterized. X-Ray structure determination revealed that complex 1 has a solvated dimeric structure, and complexes 2-5 are isostructural, and have solvated monomeric structures. Each of the rare-earth metal ions is coordinated by two oxygen atoms and two nitrogen atoms from two phenoxyamido ligands and one nitrogen atom from the N(TMS)(2) group to form a distorted trigonal bipyramidal geometry. Each of the lithium atoms in complexes 2-5 is coordinated with one oxygen atom and one nitrogen atom from two different phenoxyamido groups, and one oxygen atom from one THF molecule to form a trigonal planar geometry. Furthermore, the catalytic behavior of complexes 2-5 for the ring-opening polymerization of l-lactide was explored.

  13. Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Toutianoush, Ali [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); El-Hashani, Ashraf [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Schnepf, Judit [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Tieke, Bernd [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany)]. E-mail: Tieke@Uni-Koeln.de

    2005-06-30

    Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors {alpha} (NaCl/MgCl{sub 2}) and {alpha} (NaCl/ZnCl{sub 2}) being 43 and 20. Rare earth metal chlorides LnCl{sub 3} with Ln being La, Ce, Pr and Sm and the related YCl{sub 3} were strongly rejected from the membrane, the theoretical separation factors {alpha} (NaCl/LaCl{sub 3}) and {alpha} (NaCl/YCl{sub 3}) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane.

  14. Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

    International Nuclear Information System (INIS)

    Toutianoush, Ali; El-Hashani, Ashraf; Schnepf, Judit; Tieke, Bernd

    2005-01-01

    Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors α (NaCl/MgCl 2 ) and α (NaCl/ZnCl 2 ) being 43 and 20. Rare earth metal chlorides LnCl 3 with Ln being La, Ce, Pr and Sm and the related YCl 3 were strongly rejected from the membrane, the theoretical separation factors α (NaCl/LaCl 3 ) and α (NaCl/YCl 3 ) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane

  15. Observation of coherent population transfer in a four-level tripod system with a rare-earth-metal-ion-doped crystal

    International Nuclear Information System (INIS)

    Goto, Hayato; Ichimura, Kouichi

    2007-01-01

    Coherent population transfer in a laser-driven four-level system in a tripod configuration is experimentally investigated with a rare-earth-metal-ion-doped crystal (Pr 3+ :Y 2 SiO 5 ). The population transfers observed here indicate that a main process inducing them is not optical pumping, which is an incoherent process inducing population transfer. Moreover, numerical simulation, which well reproduces the experimental results, also shows that the process inducing the observed population transfers is similar to stimulated Raman adiabatic passage (STIRAP) in the sense that this process possesses characteristic features of STIRAP

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

    International Nuclear Information System (INIS)

    Hamdy, Abdel Salam; Butt, Darryl P.

    2013-01-01

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

  17. Phase characteristics of rare earth elements in metallic fuel for a sodium-cooled fast reactor by injection casting

    Energy Technology Data Exchange (ETDEWEB)

    Kuk, Seoung Woo, E-mail: swkuk@kaeri.re.kr [Next Generation Fuel Development Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon, 34057 (Korea, Republic of); Kim, Ki Hwan; Kim, Jong Hwan; Song, Hoon; Oh, Seok Jin; Park, Jeong-Yong; Lee, Chan Bock [Next Generation Fuel Development Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon, 34057 (Korea, Republic of); Youn, Young-Sang [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon, 34057 (Korea, Republic of); Kim, Jong-Yun [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon, 34057 (Korea, Republic of); Radiochemistry & Nuclear Nonproliferation, University of Science & Technology, Gajeong-ro 217, Yuseong-gu, Daejeon, 34113 (Korea, Republic of)

    2017-04-01

    Uranium-zirconium-rare earth (U-Zr-RE) fuel slugs for a sodium-cooled fast reactor were manufactured using a modified injection casting method, and investigated with respect to their uniformity, distribution, composition, and phase behavior according to RE content. Nd, Ce, Pr, and La were chosen as four representative lanthanide elements because they are considered to be major RE components of fuel ingots after pyroprocessing. Immiscible layers were found on the top layers of the melt-residue commensurate with higher fuel slug RE content. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) data showed that RE elements in the melt-residue were distributed uniformly throughout the fuel slugs. RE element agglomeration did not contaminate the fuel slugs but strongly affected the RE content of the slugs.

  18. Distribution behavior of uranium, neptunium, rare-earth elements (Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiCl-KCl eutectic salt and liquid cadmium or bismuth

    International Nuclear Information System (INIS)

    Kurata, M.; Sakamura, Y.; Hijikata, T.; Kinoshita, K.

    1995-01-01

    Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCl eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl/Bi system were by one or two orders of magnitude larger than those in the LiCl-KCl/Cd system. On the contrary, the separation factors of alkaline-earth metals and divalent rare-earth elements to trivalent rare-earth elements were by one or two orders of magnitude smaller in the LiCl-KCl/Bi system. (orig.)

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  1. Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

    Science.gov (United States)

    Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

    2010-04-07

    The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

  2. Effects of sulfur addition on pitting corrosion and machinability behavior of super duplex stainless steel containing rare earth metals: Part 2

    International Nuclear Information System (INIS)

    Jeon, Soon-Hyeok; Kim, Soon-Tae; Lee, In-Sung; Park, Yong-Soo

    2010-01-01

    Research highlights: → The mechanisms on the effects of rare earth metals (REM) and sulfur (S) additions on the initiation and propagation of pitting corrosion and machinabillity of a super duplex stainless steel (SDSS) were elucidated → It was found that, in consideration of the ratio of lifetime (the resistance to pitting corrosion) to cost (machining and raw material), a costly austenitic stainless steel with high Ni , medium Mo and low N can be replaced by the high S and REM added SDSS with 7 wt.% Ni-4 wt% Mo-0.3 wt.% N → The resistance to pitting corrosion of the tested super duplex stainless steel was affected by the type of inclusions, the preferential interface areas between inclusions and the substrate, and the PREN difference between the γ-phase and the α-phase for the initiation and propagation of the pitting corrosion. - Abstract: To elucidate the effects of sulfur addition on pitting corrosion and machinability behavior of alloys containing rare earth metals, a potentiostatic polarization test, a critical pitting temperature test, a SEM-EDS analysis of inclusions, and a tool life test were conducted. As sulfur content increased, the resistance to pitting corrosion decreased due to the formation of numerous manganese sulfides deteriorating the corrosion resistance and an increase in the preferential interface areas for the initiation of the pitting corrosion. With an increase in sulfur content, the tool life increased due to the lubricating films of manganese sulfides adhering to tool surface.

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

    International Nuclear Information System (INIS)

    Soldenhoff, Karin; Ho, Elizabeth

    2015-01-01

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

  4. Synergistic extraction and separation of yttrium from heavy rare earths using mixture of sec-octylphenoxy acetic acid and bis(2,4,4-trimethylpentyl)phosphinic acid

    International Nuclear Information System (INIS)

    Sun Xiaobo; Zhao Junmei; Meng Shulan; Li Deqian

    2005-01-01

    Synergistic extraction and separation of yttrium (Y) from heavy rare earths (HRE) in chloride medium using mixture of sec-octylphenoxy acetic acid (CA-12, HA) and bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272, HL) in n-heptane has been investigated. The synergistic enhancement coefficients, R max , were obtained for Ho 3+ (5.12), Y 3+ (5.34), Er 3+ (7.04), Tm 3+ (7.50), Yb 3+ (13.12) and Lu 3+ (17.58). The separation factors (SF) between Y 3+ and HRE were obtained, and it was found that Er 3+ would form the new complex as ErH 6 A 4 L 5 in the mixture system. A cation exchange mechanism was proposed. The equilibrium constant, formation constant and thermodynamic parameters such as ΔG = -18.48 kJ/mol, ΔH = -1.36 kJ/mol and ΔS = 0.058 kJ/mol were determined. The CA-12 and Cyanex272 mixture system showed higher extraction efficiency, larger separation factors as well as excellent stripping behaviors. The application potential of the mixture system to separate Y from HRE has been discussed

  5. Uniform Distribution of Yttrium and Heavy Rare Earth Elements in Round Top Mountain Rhyolite Deposit , Sierra Blanca Texas, USA: Data, Significance, and Origin

    Science.gov (United States)

    Pingitore, N. E., Jr.; Clague, J. W.; Gorski, D.

    2014-12-01

    The Round Top Mountain peraluminous rhyolite, exposed at the surface in Sierra Blanca, Hudspeth County, west Texas, USA, is enriched in yttrium and heavy rare earth elements (YHREEs). Other potentially valuable elements in the deposit include Be, Li, U, Th, Sn, F, Nb, and Ta. Texas Rare Earth Resources Corp. proposes to extract the YHREEs from the host mineral variety yttrofluorite by inexpensive heap leaching with dilute sulfuric acid, which also releases some of the Be, Li, U, F, and Th from other soluble minor minerals. Data: Feldspars and quartz comprise 90-95% of the rhyolite, with pheonocrysts of up to 250 microns set in an aphanitic matrix that hosts the typically sub-micron target yttrofluorite. Reverse circulation cuttings from some 100 drill holes, two drill cores, and outcrop and trench observations suggest striking physical homogeneity through this billion-plus ton surface-exposed laccolith, about 1200 feet high and a mile in diameter (375 x 1600 m). Gray to pink, and other minor hues, color variation derives from magnetite—hematite redox reaction. Plots of Y, 13 REEs, U, Th, and Nb analyses from over 1500 samples collected from 64 drill holes (color codes in figure) exhibit remarkably little variation in the concentration of these elements with geographic position or depth within the laccolith. Importance: Uniform mineralization grades help insure against the mining production surprises often associated with vein deposits and heterogeneous open pit deposits. At Round Top, mine feedstock can be relatively constant over the life of the mine (multiple decades), so the mechanical mining process can be optimized early on and not need expensive alterations later. Likewise, the chemical and physical parameters of the heap leach can be perfected. The sensitive and expensive process of extraction of elements and element groups from the pregnant leach solution and purification also can be optimized. Origin: The remarkable homogeneity of the YHREE distribution

  6. Syntheses of rare-earth metal oxide nanotubes by the sol-gel method assisted with porous anodic aluminum oxide templates

    International Nuclear Information System (INIS)

    Kuang Qin; Lin Zhiwei; Lian Wei; Jiang Zhiyuan; Xie Zhaoxiong; Huang Rongbin; Zheng Lansun

    2007-01-01

    In this paper, we report a versatile synthetic method of ordered rare-earth metal (RE) oxide nanotubes. RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction (XRD) have been employed to characterize the morphology and composition of the as-prepared nanotubes. It is found that as-prepared RE oxides evolve into bamboo-like nanotubes and entirely hollow nanotubes. A new possible formation mechanism of RE oxide nanotubes in the AAO channels is proposed. These high-quantity RE oxide nanotubes are expected to have promising applications in many areas such as luminescent materials, catalysts, magnets, etc. - Graphical abstract: A versatile synthetic method for the preparation of ordered rare-earth (RE) oxide nanotubes is reported, by which RE (RE=Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) oxide nanotubes were successfully prepared from corresponding RE nitrate solution via the sol-gel method assisted with porous anodic aluminum oxide (AAO) templates

  7. Rare earth intermetallic compounds produced by a reduction-diffusion process

    International Nuclear Information System (INIS)

    Cech, R.E.

    1975-01-01

    A reduction-diffusion process is given for producing novel rare earth intermetallic compounds, such as cobalt--rare earth intermetallic compounds, especially compounds useful in preparing permanent magnets. A particulate mixture of rare earth metal halide, cobalt and calcium hydride is heated to effect reduction of the rare earth metal halide and to diffuse the resulting rare earth metal into the cobalt to form the intermetallic compound

  8. Heavy metals

    OpenAIRE

    Adriano, Domy; VANGRONSVELD, Jaco; Bolan, N.S.; Wenzel, W.W.

    2005-01-01

    - Sources of Metals in the Environment - Environmental Contamination - Retention and Dynamics of Metals in Soils - Adsorption - Complexation - Precipitation - Bioavailability–Natural Attenuation Interactions - Biological Response to Metals - Soil Remediation

  9. Remediation and upgrading of old, inadequate waste management facilities. Integrated waste management system for rare earth and rare metal industry at Sillamaee, Estonia, former uranium facility

    International Nuclear Information System (INIS)

    Kaasik, Tonis; Siinmaa, Anti

    2001-01-01

    Full text: The Sillamaee Metallurgical Plant was built in 1946-1948 at Sillamaee, in North-East Estonia, ca 190 km from Tallinn. Target product was uranium, mostly in form of yellow cake (U 3 O 8 ) for Soviet nuclear program. Uranium ore processing continued from 1948 to 1977, totally 4,013,000 tons of uranium ore were processed at Sillamaee plant. In early 1970s the plant introduced a new production line - rare earth elements. Rare earths were until 1991 produced from loparite (later from semi-processed loparite) - rare earths, niobium, tantalum and NORM-containing ore for Kola peninsula, Russia; later. All wastes were, as typical to hydrometallurgical processing all over the world, discharged to a large, 40 ha liquid waste depository - tailings pond, what in Sillamaee case was designed to discharge all liquid constituents slowly to the Baltic Sea. All uranium related activities were stopped in 1990, when only rare earth and rare metal production lines remained operational. The plant was 100 % privatized in 1997 and is today operated by Silmet Ltd., processing annually up to 8 000 tons of rare earth and 2000 tons of niobium and tantalum ores. Like all industries, inherited from Soviet times, Silmet plant is today facing a serious challenge to upgrading technologies towards waste minimizations process efficiency. The historical tailings pond, containing ca 1800 tons of natural uranium and ca 800 tons of thorium, was found geotechnically unstable and leaking to the Baltic Sea, in mid 90s. Being a problem of common Baltic concern, an international remediation project was initiated by Estonian Government and plant operator in 1998. In cooperation with Estonian, Finnish, Swedish, Danish and Norwegian Governments and with assistance by the European Union, the tailings pond will be environmentally remediated - dams stabilized and surface covered, by end of 2006. Close-down and environmental remediation of the tailings pond provides plant an ultimate challenge of

  10. Non-rare earth magnetic nanoparticles

    Science.gov (United States)

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

    2017-09-26

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

  11. Anomalies in photofission of rare earth nuclei

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-09-01

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

  12. Metal, trace and rare earth element assessment in a sedimentary profile from Promissao reservoir, Sao Paulo state, Brazil, by INAA

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sharlleny A.; Franklin, Robson L., E-mail: shasilva@sp.gov.br [Companhia Ambiental do Estado de Sao Paulo (ELAI/CETESB), SP (Brazil). Setor de Quimica Inorganica; Luiz-Silva, Wanilson [Universidade Estadual de Campinas (DGRN/UNICAMP), SP (Brazil). Instituto de Geociencias. Departamento de Geologia e Recursos Naturais; Favaro, Deborah I.T., E-mail: defavaro@ipen.gov.br [Instituto de Pesquisas Energeticas e Nucleares (LAN/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Laboratorio de Analise por Ativacao Neutronica

    2015-07-01

    In the present study the preliminary results for the Promissao reservoir, situated in the Lower Tiete region covering a little more than 1% of the SP state population, is characterized by intense agropastoral activities. Its operations for generating electrical energy started in 1975. It is located at Tiete River and its hydrographic basin has a drainage area of 530 km{sup 2}. The total extension of the reservoir is 110 km along the Tiete River, with a medium depth of 20 m. A core sampler was used and a 33 cm sediment core was collected from the dam in January 2013, sliced at every 2.5 cm, totaling 13 samples. Instrumental neutron activation analysis was applied to the sediment samples in order to determine some major (Fe, K, and Na), trace (As, Ba, Br, Co, Cr, Cs, Hf, Rb, Sb, Sc, Ta, Tb, Th, U, and Zn) and rare earth elements (Ce, Eu, La, Lu, Nd, Sm, Tb, and Yb). The enrichment factor (EF) was applied to the results obtained by using North American Shale Composite, Upper Continental Crust and the concentration values of the last layer of this profile as reference values for sediment contamination index assessment. When the results for As, Cr, and Zn were compared to threshold effect level (TEL) and probable effect level (PEL) oriented values, sediments from 0-10 cm exceeded the TEL values for As (5.9 mg kg{sup -1}), all samples exceeded the PEL values for Cr (90 mg kg{sup -1}), and all samples had much lower values than TEL values for Zn (123 mg kg{sup -1}). (author)

  13. Metal, trace and rare earth element assessment in a sedimentary profile from Promissao reservoir, Sao Paulo state, Brazil, by INAA

    International Nuclear Information System (INIS)

    Silva, Sharlleny A.; Franklin, Robson L.; Luiz-Silva, Wanilson; Favaro, Deborah I.T.

    2015-01-01

    In the present study the preliminary results for the Promissao reservoir, situated in the Lower Tiete region covering a little more than 1% of the SP state population, is characterized by intense agropastoral activities. Its operations for generating electrical energy started in 1975. It is located at Tiete River and its hydrographic basin has a drainage area of 530 km 2 . The total extension of the reservoir is 110 km along the Tiete River, with a medium depth of 20 m. A core sampler was used and a 33 cm sediment core was collected from the dam in January 2013, sliced at every 2.5 cm, totaling 13 samples. Instrumental neutron activation analysis was applied to the sediment samples in order to determine some major (Fe, K, and Na), trace (As, Ba, Br, Co, Cr, Cs, Hf, Rb, Sb, Sc, Ta, Tb, Th, U, and Zn) and rare earth elements (Ce, Eu, La, Lu, Nd, Sm, Tb, and Yb). The enrichment factor (EF) was applied to the results obtained by using North American Shale Composite, Upper Continental Crust and the concentration values of the last layer of this profile as reference values for sediment contamination index assessment. When the results for As, Cr, and Zn were compared to threshold effect level (TEL) and probable effect level (PEL) oriented values, sediments from 0-10 cm exceeded the TEL values for As (5.9 mg kg -1 ), all samples exceeded the PEL values for Cr (90 mg kg -1 ), and all samples had much lower values than TEL values for Zn (123 mg kg -1 ). (author)

  14. Heavy metal jako subkultura

    OpenAIRE

    KOUTNÁ, Daniela

    2016-01-01

    This bachelor thesis deals with heavy metal subculture. Its aim is to introduce the most important branches and to show broadness of heavy metal. This bachelor thesis describes development and history, briefly shows Czech heavy metal history alongside with the biggest and most popular Czech heavy metal festivals. It shows the most dressing concerns of society against this style.

  15. Enhanced pinning in mixed rare earth-123 films

    Science.gov (United States)

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

    2009-06-16

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

  16. Rare earth superlattices

    International Nuclear Information System (INIS)

    McMorrow, D.F.

    1997-01-01

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

  17. Rare earth (3) pivalates

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  18. 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.

  19. Detection of nanocrystallinity by X-ray absorption spectroscopy in thin film transition metal/rare-earth atom, elemental and complex oxides

    International Nuclear Information System (INIS)

    Edge, L.F.; Schlom, D.G.; Stemmer, S.; Lucovsky, G.; Luning, J.

    2006-01-01

    Nanocrystallinity has been detected in the X-ray absorption spectra of transition metal and rare-earth oxides by (i) removal of d-state degeneracies in the (a) Ti and Sc L 3 spectra of TiO 2 and LaScO 3 , respectively, and (b) O K 1 spectra of Zr(Hf)O 2 , Y 2 O 3 , LaScO 3 and LaAlO 3 , and by the (ii) detection of the O-atom vacancy in the O K 1 edge ZrO 2 -Y 2 O 3 alloys. Spectroscopic detection is more sensitive than X-ray diffraction with a limit of ∼2 nm as compared to >5 mm. Other example includes detection of ZrO 2 nanocrystallinity in phase-separated Zr(Hf) silicate alloys

  20. The effect of sputter-deposition conditions on the coercive force in amorphous rare-earth - transition-metal thin films

    International Nuclear Information System (INIS)

    Davies, C.F.; Somekh, R.E.; Evetts, J.E.; Storey, P.A.

    1988-01-01

    The origins of the coercive force in amorphous rare earth - transition metal films have been investigated, the results being discussed in terms of how the growth conditions of the sputter-deposited films determine the pinning features which cause the coercive force. The authors have studied the variation of coercive force with film thickness and developed a model which enables a local pinning force per unit area to be deduced. This suggests that it should be possible to increase the coercive force by breaking up the microstructure with a multi-layered structure. An increase in coercive force obtained by making such structures with tungsten is described. They also report on the reduction in coercive force obtained when the films are deposited in the presence of a perpendicular magnetic field

  1. Environmental aspects in the processing of rare earth ores and minerals

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2011-01-01

    In India, rare earths are extracted from the mineral monazite which occurs abundantly along with other heavy minerals in the coastal beach sands. Monazite, apart from rare earths, also contains uranium and thorium. Rare earths can be obtained from monazite either by acid digestion route or by alkaline digestion route. In India, although pilot scale studies have been carried out extraction of rare earths by acid digestion route, however, alkali digestion route has been predominantly followed for commercial extraction of rare earths

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

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

    International Nuclear Information System (INIS)

    Rocha, Flavio R.; Bordon, Isabella C.C.L.; Silva, Paulo S.C.; Favaro, Deborah I.T.; Silva, Sharlleny A.; Franklin, Robson L.; Ferreira, Francisco J.

    2015-01-01

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

  4. Contributions to the rare earths to science and technology

    International Nuclear Information System (INIS)

    Spedding, F.H.

    1975-01-01

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

  5. Features of rare earth element (3) complexing

    International Nuclear Information System (INIS)

    Martynenko, L.I.

    1991-01-01

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

  6. 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.

  7. Subsurface contributions in epitaxial rare-earth silicides

    Energy Technology Data Exchange (ETDEWEB)

    Luebben, Olaf; Shvets, Igor V. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Physics, Trinity College, Dublin (Ireland); Cerda, Jorge I. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, Madrid (Spain); Chaika, Alexander N. [Institute of Solid State Physics, RAS, Chernogolovka (Russian Federation)

    2015-07-01

    Metallic thin films of heavy rare-earth silicides epitaxially grown on Si(111) substrates have been widely studied in recent years because of their appealing properties: unusually low values of the Schottky barrier height, an abrupt interface, and a small lattice mismatch. Previous studies also showed that these silicides present very similar atomic and electronic structures. Here, we examine one of these silicides (Gd{sub 3}Si{sub 5}) using scanning tunneling microscopy (STM) image simulations that go beyond the Tersoff-Hamann approach. These simulations strongly indicate an unusual STM depth sensitivity for this system.

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

    Directory of Open Access Journals (Sweden)

    T.K. Chondhekar

    2011-12-01

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

  9. Reply to Comment on the Two-lon Anisotropy in the Heavy-Rare-Earth Metals

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    The giant anisotropic two-ion couplings found in Er and Tb do not break the symmetry of the lattice. A nonspherical spin pressession due to crystal field effects was recently shown to induce such couplings from a basically isotropic interaction. The argument is here shown to be generally valid...

  10. Exchange interaction in the heavy rare-earth metals calculated from energy bands

    International Nuclear Information System (INIS)

    Lindgard, P.A.; Liu, S.H.

    1973-01-01

    The exchange interaction in the ordered phases was calculated and found to be significantly influenced by the magnetic perturbation of the conduction electron states. The exchange interaction is intrinsically temperature dependent and is anisotropic. The effect explains how it is possible to have a spiral phase of Tb, although spin wave measurements show no maximum in J/sub q/ for q not equal to 0. The energy difference between the ferromagnetic and spiral phases is of correct order of magnitude to be counterbalanced by the magnetoelastic energy. The wave vector dependent matrix element is found to be similar for Gd, Tb, Dy, and Er with a narrow central conduction electron contribution and a flat region. (U.S.)

  11. heavy metals

    African Journals Online (AJOL)

    NICO

    aDepartment of Chemistry, Tshwane University of Technology, P.O. Box 56208, Arcadia, 0007, South Africa. bSchool of Health Systems and Public Health, Faculty of Health Sciences, ... ing the levels of toxic metals in food.15,19 Compared to ET-AAS or .... mum pressure 350 psi and maximum temperature 210 °C. The.

  12. Influence of small metallic particles on the absorption and emission in amorphous materials doped with rare earths

    International Nuclear Information System (INIS)

    Malta, O.L.; Santa Cruz, P.A.; Sa, G.F. de

    1987-01-01

    The influence of small metallic clusters on the absorption and emission processes in molecular species shows a great interest as well the fundamental as the pratical point of view. This subject, which has been recently developed, covers several aspects related to the kinetics of formation of these chusters and to theirs optical properties in amorphous media. A study of this problem developed by the first time for the case of one volumetric distribution of metallic particles is presented. With this aim, fluoborate glasses doped with Eu 3+ ion which fluorescence is well known in several materials are used. (L.C.) [pt

  13. Magneto-optical measurement of anisotropy energy constant(s) for amorphous rare earth, transition metal alloys

    International Nuclear Information System (INIS)

    Uber, R.E.; Mansuripur, M.

    1988-01-01

    Optical investigation of magneto-optical films is complementary to conventional torque and VSM magnetometry. In the authors' laboratory, they are now measuring anisotropy energy constants of RE-TM thin films at temperatures from ambient to 150 0 C. An in-plane magnetic field (up to 16.5 KOe) is applied to a saturated sample with perpendicular magnetization. The movement away from the perpendicular direction is monitored using the polar Kerr effect. At the HeNe wavelength, the Kerr effect is principally due to the top 500 angstroms of the transition metal subnetwork in the films

  14. Rare earth oxide reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics for inert coating of metallic parts for petroleum extraction

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Yoggendra Prasad; Rego, Sheila Alves Bezerra da Costa; Ferreira, Ricardo Artur Sanguinetti [Universidade Federal de Pernambuco (UFPE), Recife (Brazil)

    2012-07-01

    Recent findings of largest known pre-salt petroleum reservoir in Brazil have created an intense demand for new materials capable of withstanding direct contact with the crude petroleum as it is a highly corrosive and chemically reactive fluid. Petroleum drilling equipment, storage tanks and transportation systems suffer from constant physical stress caused by chemical attack of crude petroleum on its structure. Ceramics are materials with high chemical stability in hostile environment and therefore can be used as an inert coating material to resolve such problems. To date, ceramics based on alumina are most widely used in practice where there is demand for high mechanical strength and high fracture toughness. However intrinsic fragility of ceramics is still a fatal factor for their use in mechanical structures. To improve these characteristics, usually ceramics are reinforced with one or more ceramic additives. Mechanical properties of alumina based ceramics improve considerably with the addition of TiO{sub 2}, TiN, ZrO{sub 2} etc. ceramic additives. Nucleation and propagation of cracks is a major problem for ceramic coating applications. Initial studies show that addition of small percentages of rare earth oxides can increase the toughness of the alumina based ceramics. In the present work, we have produced rare-earth oxide (CeO{sub 2}) reinforced Al{sub 2}O{sub 3}-TiO{sub 2} ceramics in proportions of 5-20 wt% TiO{sub 2} and 2%wt% CeO{sub 2} through thermomechanical processing and sintering techniques and studied there microstructural characteristics and mechanical properties. To evaluate the potential of these ceramics as inert coatings for crude petroleum extraction, storage and transportation systems, we have studied the physic-chemical and mechanical stability of these ceramics in crude petroleum environment. Our studies presented satisfactory results in terms of physic-chemical and mechanical stability of these materials for the use of 2wt% of CeO{sub 2

  15. Application of the electromotive force method with fluoride-xon electrolyte for establishing of thermodynamic properties of oxyfluorides of yttrium and rare-earth metals

    International Nuclear Information System (INIS)

    Levitskij, V.A.; Balak, G.M.

    1983-01-01

    Cells of the type (-) O 2 , Pt β v , CaF 2 β v β v CaF 2 β v CaF 2 β v β v Pt, O 2 (+) have been used for the first time to study high-temperature thermodynamic properties of Y and Nb oxyfluorides of the composition. Using the method of e. m. f., X-ray phase and chemical analyses it has been established that Y 2 O 3 and Nd 2 O 3 in the range 960-1465 K coexist with ROF oxyfluorides which are similar in composition to stoichiometric ones. On the basis of dependences E=f(T) of the cells studied ΔG deg=f(T), ΔHsub( anti T) deg and ΔSsub(anti T) deg of the YOF and NdOF formation from simple substances and R 2 O 3 and RF 3 are determined. High stability and reproducibility of potentials of the cells with oxyfluoride electrodes as well as coincidence of thermodynamic results obtained on the basis of data for independent cells testifies to the prospects of application of the above cells for thermodynamical studies of rare earth and transition metals

  16. Effects of Rare Earth Metals addition and aging treatment on the corrosion resistance and mechanical properties of super duplex stainless steels

    Science.gov (United States)

    Park, Yong-Soo; Kim, Soon-Tae; Lee, In-Sung; Song, Chi-Bok

    2002-05-01

    Effects of rare earth metals addition and aging treatment on corrosion resistance and mechanical properties of super duplex stainless steels were investigated using optical/SEM/TEM metallographic examination, an X-ray diffraction test, a potentiodynamic anodic polarization test and a tensile test. The performance of the experimental alloy with 0.32% REM addition was compared with commercial super duplex stainless steel such as SAF 2507 when they were exposed to solution annealing heat treatment and aging treatment. The corrosion resistance in Cl- environments and mechanical properties of the experimental alloy were found superior to those of the commercial duplex stainless steel. The REM with larger atomic radii than those of Cr, Mo and W may fill vacancies inside the matrix and around the grain boundaries, retarding formation of harmful intermetallic σ and η phases. In addition, fine REM oxides/oxy-sulfides (1-3 μm) seemed to enhance the retardation effects. With REM additions, strength and ductility increased due to the phase and grain refinement caused by fine REM oxides and oxy-sulfides.

  17. Rare earth industries: Downstream business

    International Nuclear Information System (INIS)

    2011-01-01

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

  18. Radiological safety in extraction of rare earths in India: regulatory control

    International Nuclear Information System (INIS)

    Sinha, S.; Bhattacharya, R.

    2011-01-01

    The term 'rare earths' refers to a group of f-block elements in the periodic table including those with atomic numbers 57 (Lanthanum) to 71 (Lutetium), as well as the transition metals Yttrium (39) and Scandium (21). Economically extractable concentrations of rare earths are found in minerals such as monazite, bastnaesite, cerites, xenotime etc. Of these, monazite forms the main source for rare earths in India, which along with other heavy minerals is found abundantly in the coastal beach sands. However, in addition to rare earths, monazite also contains 0.35% U 3 O 8 and 8-9% ThO 2 . Hence, extraction of rare earths involves chemical separation of the rare earths from thorium and uranium which are radioactive. The processing and extraction of rare earths from monazite therefore invariably results in occupational radiation exposure to the workers involved in these operations. In addition, in the process of removal of radioactivity from rare earths, radioactive solid waste gets generated which has 2 2 8Ra concentration in the range 2000-5000 Bq/g. Unregulated disposal of such high active waste would not only result in contamination of the soil but the radionuclides would eventually enter the food chain and lead to internal exposure of the general public. Therefore such facilities involved in recovery of rare earths from monazite attract the provisions of radiological safety regulations. Atomic Energy Regulatory Board of India has been enforcing the provisions of The Atomic Energy (Radiation Protection) Rules, 2004 and The Atomic Energy (Safe Disposal of Radioactive Waste) Rules, 1987 in these facilities. This paper shall discuss the associated radiological hazard involved in recovery of rare earths from monazite. It shall also highlight the regulatory requirements for controlling the occupational exposure of workers during design stage such as requirements on lay out of the building, ventilation, containment of radioactivity, etc and also the during operational

  19. Synthesis of main group, rare-earth, and d{sup 0} metal complexes containing beta-hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Ka King [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    >F5)3 give the expected dicationic M{HB(C6F5)3}2L (M = Ca, Yb; L = THF2 or TMEDA) and dicationic mono(silylalkyl) LnC(SiHMe2)3{HB(C6F5)3}2 (Ln = Y, Lu, La), respectively. Salt metathesis reactions of Cp2(NR2)ZrX (X = Cl, I, OTf; R = t-Bu, SiHMe2) and lithium hydrosilazide ultimately afford hydride products Cp2(NR2)ZrH that suggest unusual β-hydrogen elimination processes. A likely intermediate in one of these reactions, Cp2Zr[N(SiHMe2)t-Bu][N(SiHMe2)2], is isolated under controlled synthetic conditions. Addition of alkali metal salts to this zirconium hydrosilazide compound produces the corresponding zirconium hydride. However as conditions are varied, a number of other pathways are also accessible, including C-H/Si-H dehydrocoupling, γ-abstraction of a CH, and β-abstraction of a SiH. Our observations suggest that the conversion of (hydrosilazido)zirconocene to zirconium hydride does not follow the classical four-center β- elimination mechanism.

  20. Study On Beneficiation Technology Of Dong Pao Rare-Earth-Barite-Fluorite With Two Product Plans About Content And Recovery Of Rare-Earth Fine Ores

    International Nuclear Information System (INIS)

    Duong Van Su; Truong Thi Ai; Bui Ba Duy; Bui Thi Bay; Nguyen Hong Ha; Le Thi Hong Ha; Doan Thi Mo; Doan Dac Ban; Nguyen Hoang Son

    2014-01-01

    The ore sample used in the research was taken from the F3 ore bodies and the sample of the F7, F9 and F16 ore bodies which contain the average of 5.98% TR 2 O 3 ; they are multi-metals ore which is difficult to enrich, highly weather with very complex ingredients. The process of the experiment is the ore is crushed, ground, screened and classified reasonably to -0.1 mm and divided into 3 particle size with the following technique: (1) -0.020 mm is primary sludge and the rare-earth fine ore; (2) 0.075-1 mm is gotten through the sludge concentrating table with the output is the 2 parts: the heavy part which is dried magnetic separator with high magnetism to get the rare-earth fine ore and the light one; (3) Light minerals, non-magnetic and ferromagnetic minerals group are ground together to 85% of them get size within -0.075 mm then mix it with 0.020-0.075 mm group. Using flotation separator, get barite-rare earth mixture and fluorite. After that, we separate this mixture by secondary flotation and get refined rare earth, barite and fluorite mineral. The result of the theme: (1) product plan A-rare-earth fine ore has TR 2 O 3 content archive 42.07% with recovery is 69.70%; (2) product plan B-rare-earth fine ore has TR 2 O 3 content archive 29.64% with recovery is 80.01%. (author)

  1. 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.

  2. Report on the stakes of strategic metals: the case of rare earth metals. Report of the 8 March 2011 public audition and of the presentation of conclusion on the 21 June 2011

    International Nuclear Information System (INIS)

    Biraux, C.; Kert, Ch.

    2011-08-01

    The first part of this report proposes the content of a round table which gathered several experts in the field of rare earth metals (researchers, representatives of specialized branches companies like Saint-Gobain, Rhodia). The second part proposes the content of another round table which gathered experts who discussed the future of strategic metals like lithium, titanium or rhenium. Several issues are discussed: fundamental physics, physical and chemical properties, quantum physics, areas of interests (magnets, catalysis, ceramics, and photovoltaic arrays), availability, supplies and suppliers, processes, technological challenges and opportunities, and so on

  3. Safety aspects in rare earths recovery

    International Nuclear Information System (INIS)

    Bhattacharya, R.

    2014-01-01

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

  4. Calcium substitution in rare-earth metal germanides with the hexagonal Mn{sub 5}Si{sub 3} structure type. structural characterization of the extended series RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Rare-earth metal)

    Energy Technology Data Exchange (ETDEWEB)

    Suen, Nian-Tzu; Broda, Matthew; Bobev, Svilen, E-mail: bobev@udel.edu

    2014-09-15

    Reported are the synthesis and the structural characterization of an extended family of rare-earth metal–germanides with a general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu; x<2). All twelve phases are isotypic, crystallizing with the Mn{sub 5}Si{sub 3} structure type (Pearson index hP16, hexagonal space group P6{sub 3}/mcm); they are the Ca-substituted variants of the corresponding RE{sub 5}Ge{sub 3} binaries. Across the series, despite some small variations in the Ca-uptake, the unit cell volumes decrease monotonically, following the lanthanide contraction. Temperature dependent DC magnetization measurements reveal paramagnetic behavior in the high temperature range, and the obtained effective moments are consistent with free-ion RE{sup 3+} ground state, as expected from prior studies of the binary RE{sub 5}Ge{sub 3} phases. The onset of magnetic ordering is observed in the low temperature range, and complex magnetic interactions (ferromagnetic/ferrimagnetic) can be inferred, different from the binary phases RE{sub 5}Ge{sub 3}, which are known as antiferromagnetic. In order to understand the role of Ca in the bonding, the electronic structures of the La{sub 5}Ge{sub 3} and the hypothetical compounds La{sub 2}Ca{sub 3}Ge{sub 3} and La{sub 3}Ca{sub 2}Ge{sub 3} with ordered metal atoms are compared and discussed. - Graphical abstract: The family of rare-earth metal–calcium–germanides with the general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) crystallize in the hexagonal space group P6{sub 3}/mcm (No. 193, Pearson symbol hP16) with a structure that is a variant of the Mn{sub 5}Si{sub 3} structure type. - Highlights: • The newly synthesized RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) constitute an extended family. • The structure is a substitution variant of the hexagonal Mn{sub 5}Si{sub 3} structure type. • Ca-uptake is the highest in the early members, and

  5. Novel condensation of Au-centered trigonal prisms in rare-earth-metal-rich tellurides: Er7Au2Te2 and Lu7Au2Te2.

    Science.gov (United States)

    Gupta, Shalabh; Corbett, John D

    2010-07-14

    A new monoclinic structure occurs for Er(7)Au(2)Te(2) according to X-ray diffraction analysis of single crystals grown at 1200 degrees C: C2/m, Z = 4, a = 17.8310(9) A, b = 3.9819(5) A, c = 16.9089(9) A, beta = 104.361(4) degrees. The isostructural Lu(7)Au(2)Te(2) also exists according to X-ray powder pattern means, a = 17.536(4) A, b = 3.9719(4) A, c = 16.695(2) A, beta = 104.33(1) degrees. The structure contains zigzag chains of condensed, Au-centered tricapped trigonal prisms (TCTP) of Er along c that also share basal faces along b to generate puckered sheets. Further bi-face-capping Er atoms between these generate the three dimensional network along a, with tellurium in cavities outlined by augmented trigonal prismatic Er polyhedra. Bonding analysis via LMTO-DFT methods reveal very significant Er-Au bonding interactions, as quantified by their energy-weighted Hamilton overlap populations (-ICOHP), approximately 49% of the total for all interactions. These and similar Er-Te contributions sharply contrast with the small Er-Er population, only approximately 14% of the total in spite of the high proportion of Er-Er contacts. The strong polar bonding of Er to the electronegative Au and Te leaves Er relatively oxidized, with many of its 5d states falling above the Fermi level and empty. The contradiction with customary representations of structures that highlight rare-earth metal clusters is manifest. The large Er-Au Hamilton overlap population is in accord with the strong bonding between early and late transition metals first noted by Brewer in 1973. The relationship of this structure to the more distorted orthorhombic (Imm2) structure type of neighboring Dy(7)Ir(2)Te(2) is considered.

  6. Soil heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Sherameti, Irena [Jena Univ. (Germany). Inst. fuer Allgemeine Botanik und Pflanzenphysiologie; Varma, Ajit (eds.) [Amity Univ., Uttar Pradesh (India). Amity Inst. of Microbial Technology; Amity Science, Technology and Innovation Foundation, Noida, UP (India)

    2010-07-01

    Human activities have dramatically changed the composition and organisation of soils. Industrial and urban wastes, agricultural application and also mining activities resulted in an increased concentration of heavy metals in soils. How plants and soil microorganisms cope with this situation and the sophisticated techniques developed for survival in contaminated soils is discussed in this volume. The topics presented include: the general role of heavy metals in biological soil systems; the relation of inorganic and organic pollutions; heavy metal, salt tolerance and combined effects with salinity; effects on abuscular mycorrhizal and on saprophytic soil fungi; heavy metal resistance by streptomycetes; trace element determination of environmental samples; the use of microbiological communities as indicators; phytostabilization of lead polluted sites by native plants; effects of soil earthworms on removal of heavy metals and the remediation of heavy metal contaminated tropical land. (orig.)

  7. On the structure of heavy metals

    International Nuclear Information System (INIS)

    Friedel, J.

    1958-01-01

    The properties of the last series of Mendeleef's table are compared with those of the elements of the preceding series. This comparison suggests an electronic structure of the 'transition metal' type, with narrow bands, at the beginning of this series (up to certain phases at least of plutonium); then of the rare earth metal type, with independent non-saturated internal layers, further on in the series. The 5 f orbits seem to play an important part in these two types of structure, from uranium on. A more detailed study of the very heavy elements (americium and beyond) and alloys would allow these conclusions to be confirmed. Certain general points, concerning the nature of homopolar connections and paramagnetism in the transition metals, are developed in an additional section. (author) [fr

  8. Rare earths as a future resource

    International Nuclear Information System (INIS)

    Cornell, D.H.

    1988-01-01

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

  9. Electroluminescence color tuning between green and red from metal-oxide-semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

    Science.gov (United States)

    Matsuda, Toshihiro; Hattori, Fumihiro; Iwata, Hideyuki; Ohzone, Takashi

    2018-04-01

    Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +I G current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiO x ], (Tb/Eu/Ba)SiO x , and SiO x -rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiO x -rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.

  10. Creating a multi-national development platform: Thorium energy and rare earth value chain

    International Nuclear Information System (INIS)

    Kennedy, J.; Kutsch, J.

    2014-01-01

    Rare earths and thorium are linked at the mineralogical level. Changes in thorium regulations and liabilities resulted in the development of excessive market concentrations in the rare earth value chain. High value monazite rare earth resources, a by-product of heavy mineral sands mining, constituted a significant portion of global rare earth supply (and nearly 100% of heavy rare earths) until legislative changes, interpretation and enforcement regarding “source materials” in the early 1980s eliminated these materials from the supply chain.

  11. Quantum Theory of Rare-Earth Magnets

    Science.gov (United States)

    Miyake, Takashi; Akai, Hisazumi

    2018-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  13. Advances in the hydrometallurgical separation techniques of high purity rare earth elements

    International Nuclear Information System (INIS)

    Vijayalakshmi, R.; Kain, V.

    2017-01-01

    Rare Earths are a series of 15 chemically similar elements that occur together in monazite mineral found in the beach sands of Kerala, Tamil Nadu and Orissa. The rare earth elements (REE) are becoming increasingly strategically important considering their essential role in permanent magnets such as, SmCo_5, Sm_2Co_1_7 and Nd_2Fe_1_4B, phosphors for LED screens and lamps, rechargeable nickel metal hydride batteries and catalysts and other green applications. The increasing popularity of hybrid and electric cars, wind turbines and compact fluorescent lamps is causing an increase in the demand and price of REE. The European Commission considers the REE as the most critical raw materials group, with the highest supply risk. According to the medium-term criticality matrix of the U.S. Department of Energy (DOE), the five most critical REE are neodymium (Nd), europium (Eu), terbium (Tb), dysprosium (Dy) and yttrium (Y). China is presently producing more than 90% of all rare earths, although they possess less than 405 of the proven reserves. Due to large and increasing domestic demands, China tightened its REE export quota from 2012 onwards. These export quotas caused serious problems for REE users outside of China. Fortunately India is blessed with large resources of rare earths in the form of monazite found in the beach sands of Kerala, Tamil Nadu and Orissa. Indian Rare Earths Limited at Aluva near Kochi produces mainly mixed rare earths chloride and till recent past exporting to USA, UK, France, Japan, etc. They have revived their rare earth separation plant to meet the in-house demands of the strategic, defense and nuclear industry. This paper discusses the recent advances made in hydrometallurgical separation techniques based on solvent extraction technique, ion-exchange resins, hollow fibre membrane extractor, solvent encapsulated polymeric beads, etc for the production of high purity rare earth elements from both primary (Monazite, xenotime) and secondary sources

  14. 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. Copyright © 2016 Elsevier Ltd

  15. Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles

    Directory of Open Access Journals (Sweden)

    Timothy A. DeVol

    2010-03-01

    Full Text Available 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 luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-shell nanoparticles, and the CaF2-LaF3 system.

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

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  17. 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

  18. Sc, Y, La-Lu - Rare Earth Elements

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    At present extensive efforts are being made in completing work on system number Rare Earth Elements. Part A is devoted to the occurrence of these elements on the earth and in the universe. Part B deals with the pure metals; the 7 volumes published cover the description of the separation from the raw materials, the preparation of pure metals,their uses and toxicology, the physical properties of nuclei, atoms, molecules, and isotopes; in addition the behavior of ions in solution and the electrochemical behavior of rare earth elements are described. The compounds are described in Part C. Part D with 6 volumes has been devoted to the description of coordination compounds and is completed. The volume ''Rare Earth Elements C 10'' deals with the rare earth tellurides, oxide tellurides, tellurates, telluride halides, tellurate halides, sulfide tellurides, selenide tellurides, and alkali rare earth tellurates. Another topic of this volume are the compounds of the rare earth elements with polonium. So far as meaningful and in accordance with all earlier volumes of ''Rare Earth Elements'' Series C, comparative data are presented in sections preceding treatment of the individual compounds and systems

  19. New Trident Molecule with Phosphoric Acid Functionality for Trivalent Rare Earth Extraction

    Directory of Open Access Journals (Sweden)

    Keisuke Ohto

    2017-11-01

    Full Text Available Tripodal extraction reagent with three phosphoric acid groups, together with the corresponding monopodal molecule has been prepared to investigate some metals extraction behavior, in particular, trivalent rare earth elements (REEs. The tripodal reagent exhibited extremely high selectivity for metals with high valency such as Zr(IV, In(III, Lu(III, and Fe(III. Tripodal reagent also exhibited exceptionally high extraction ability compared with the corresponding monopodal one in the extraction of trivalent rare earths. The result for the stoichiometry of tripodal reagent to heavy rare earths showed the inflection point between Er (2:1 for a ligand with ion and Tm (1:1. The extraction reactions were determined for all rare earths with both reagents. The extraction equilibrium constants (Kex, the separation factors (β, half pH values (pH1/2, difference half pH values (ΔpH1/2 for extraction of REEs with both reagents are estimated.

  20. Facile synthesis of highly biocompatible folic acid-functionalised SiO2 nanoparticles encapsulating rare-earth metal complexes, and their application in targeted drug delivery.

    Science.gov (United States)

    Xu, Xiuling; Hu, Fan; Shuai, Qi

    2017-11-14

    Mesoporous silica core-shell nanospheres encapsulating a rare-earth metal complex (RC) were first synthesised through a facile W/O (water in oil) inverse microemulsion method. In order to achieve targeted complex delivery, folic acid (FA) was used as the targeting component due to its high affinity for over-expressed folate receptors (FRs) in cancer cells. The RC 2 @SiO 2 -FA nanospheres were characterised via ultraviolet-visible light absorption spectroscopy (UV-vis spectroscopy), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microwave method was used to synthesise five RC cores based on 4-chlorophenoxyacetic acid, and their crystal structures were further confirmed using X-ray diffraction. The five RC cores have the following chemical formulae: [Er 2 (p-CPA) 6 (H 2 O) 6 ] RC 1 , [Ho 2 (p-CPA) 6 (H 2 O) 6 ] RC 2 , [Sm(p-CPA) 3 (H 2 O)] RC 3 , [Pr(p-CPA) 3 (H 2 O)]·3H 2 O RC 4 and [Ce(p-CPA) 3 (H 2 O) 2 ]·2H 2 O RC 5 . The carboxyl groups showed two kinds of coordination modes, namely μ 2 -η 1 :η 1 and μ 2 -η 1 :η 2 , among RC 1 -RC 5 . The flexible -OCH 2 COO- spacer group, which can undergo rotation of its C-O and C-C bonds, offered great potential for structural diversity. In vivo experiments revealed that the nanospheres exhibited no obvious cytotoxicity on HepG2 cells and 293 T cells, even at concentrations of up to 80 μg mL -1 . Nevertheless, all of the RC cores showed a certain degree of anti-tumour efficacy; in particular, RC 2 showed the strongest cytotoxicity against HepG2 cells. Interestingly, the cytotoxicity of all of the RC 2 @SiO 2 -FA nanospheres was higher than that of lone RC 2 . These types of FA-targeted mesoporous silica nanocarriers can be used for the delivery of anti-tumour RC, and provide a basis for the further study of affordable non-platinum-based complexes.

  1. 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.

  2. Rare earths from uranium mineralization occurrences in the Permian of the Gemericum, the Western Carpathians

    International Nuclear Information System (INIS)

    Rojkovic, I.; Medved, J.; Walzel, E.; Posta, S.; Sulovsky, P.

    1989-01-01

    Uranium mineralization in the Permian of the Gemericium is accompanied by apatite, monazite and xenotime. The study of rare earth elements distribution is based on the results of instrumental neutron activation analysis and optical emission spectroscopy analysis of rocks and energy-dispersive X-ray microanalyses of minerals. The main light rare earth elements bearing mineral is monazite; for heavy rare earth elements it is xenotime. The rocks accompanying uranium mineralization have increased rare earth elements contents. The mobilization and concentration of uranium mineralization took place during the Alpine metallogenic processes. These processes were also associated with rare earth elements mobilization is which total and selective enrichment in light rare earth elements and heavy rare earth elements was observed. (author). 12 figs., 6 tabs., 5 refs

  3. Rare Earth Garnet Selective Emitter

    Science.gov (United States)

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

    1994-01-01

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

  4. Rare earth industries: Upstream business

    International Nuclear Information System (INIS)

    2011-01-01

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

  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. Rare earth niobate coordination polymers

    Science.gov (United States)

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

    2018-03-01

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

  7. Leaching Process of Rare Earth Elements, Gallium and Niobium in a Coal-Bearing Strata-Hosted Rare Metal Deposit—A Case Study from the Late Permian Tuff in the Zhongliangshan Mine, Chongqing

    OpenAIRE

    Jianhua Zou; Heming Tian; Zhen Wang

    2017-01-01

    The tuff, a part of coal-bearing strata, in the Zhongliangshan coal mine, Chongqing, southwestern China, hosts a rare metal deposit enriched in rare earth elements (REE), Ga and Nb. However, the extraction techniques directly related to the recovery of rare metals in coal-bearing strata have been little-studied in the literature. The purpose of this paper is to investigate the extractability of REE, Ga and Nb in the tuff in the Zhongliangshan mine using the alkaline sintering-water immersion-...

  8. A comparative study between the dissolution and the leaching methods for the separation of rare earths, uranium and thorium from hydrous metal oxide cake obtained by the alkaline digestion of monazite

    International Nuclear Information System (INIS)

    Chayavadhanangkur, C.; Busamongkol, A.; Hongsirinirachorn, S.; Rodthongkom, C.; Sirisena, K.

    1986-12-01

    Methods for the group-separation of rare-earths, thorium and uranium from hydrous metal oxide cake obtained by the alkaline digestion of monazite were studied. Leaching of the hydrous metal oxide cake at pH between 4-5 separates the elements under investigation into 3 major groups which are suitable to be used as feed materials for further purification. Total dissolution and gradient precipitation at pH 4-5 yields a poorer separation in comparison to the leaching method

  9. Superconductivity in Ternary Rare-Earth Transition Metal Silicides and Germanides with the SCANDIUM(5) COBALT(4) SILICON(10)-TYPE Structure.

    Science.gov (United States)

    Berg, Linda Sue

    A systematic study of the superconducting and normal state properties of some ternary rare earth transition metal silicides and germanides of the Sc(,5)Co(,4)Si(,10) -type is reported in this work. Low temperature heat capacity measurements indicate the presence of a complicated phonon density of states in these structurally complex compounds. A better description of the phonon spectrum of the high T(,c) materials, Sc(,5)Rh(,4)Si(,10), Sc(,5)Ir(,4)Si(,10), and Y(,5)Os(,4)Ge(,10), given by a model proposed by Junod et al.('1), is presented and discussed. The large values of (DELTA)C/(gamma)(,n)T(,c) and the electron-phonon coupling constant for these high T(,c) compounds indicate that they are strong-coupled superconductors. Relative to other ternary superconductors, many of these materials have large Debye temperatures. The BSC theory does not seem to afford an adequate description of the supercon- ducting state in these compounds. DC electrical resistivity measurements on these compounds show resistivity behaviors deviating from those exhibited by simple metals. The (rho)(T) data for Y(,5)Ir(,4)Si(,10), Lu(,5)Rh(,4)Si(,10), Lu(,5)Ir(,4)Si(,10), and Y(,5)Os(,4)Ge(,10), indicate the presence of anomalies. Static molar magnetic susceptibility measurements performed on these compounds indicate (1) a small effective magnetic moment of 0.26(mu)(,B) on the Co atom and (2) anomalous behaviors in the Lu(,5)Rh(,4)Si(,10), Lu(,5)Ir(,4)Si(,10), Y(,5)Ir(,4)Si(,10), Lu(,5)Ir(,4)Ge(,10), and Y(,5)Rh(,4)Ge(,10) data. It is suggested that the same mechanism, namely, the forma- tion of a charge- or spin-density wave, is causing the anomalous behaviors in both the resistivity and susceptibility data. Lastly, upper critical magnetic field measurements were performed on Sc(,5)Co(,4)Si(,10), Sc(,5)Rh(,4)Si(,10), Sc(,5)Ir(,4)Si(,10), Lu(,5)Rh(,4)Si(,10), Lu(,5)Ir(,4)Si(,10), and Y(,5)Os(,4)Ge(,10). Relative to the other five samples, Y(,5)Os(,4)Ge(,10) exhibits very high values for (-d

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

    International Nuclear Information System (INIS)

    Krupke, W.F.

    1976-01-01

    The dynamical properties of three types of RE 3+ molecular vapors were considered: (1) rare earth trihalogens, (2) rare earth trihalogens complexed with transition metal trihalogens, and (3) rare earth chelates. Radiative and nonradiative (unimolecular and bimolecular) transition probabilities have been calculated using phenomenological models predicted on the unique electronic structure of the triply ionized RE ion (well shielded ground electronic configuration of equivalent of electrons). Although all the lanthanide ions have been treated in some detail, specific results are presented for the Nd 3+ and Tb 3+ ions to illustrate the systematics of these vapors as a class of new laser media. Once verified, these phenomenological models will provide a powerful tool for the directed experimental exploration of these systems. Because of the structural similarity to the triply ionized actinides, comments offered here for the lanthanide rare earth series generally apply to gaseous actinide lasers which are also under consideration

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

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  12. Handbook on the physics and chemistry of rare earths

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  13. Use of a piezo-electric quartz as substrate for the preparation of self-supporting rare earth targets, in metallic form, not oxidized

    International Nuclear Information System (INIS)

    Bonetti, C.

    1975-01-01

    A technique for preparing rare earth self-supporting targets is described. These high purity foils are used for nuclear spectroscopy, with a tandem Van de Graaff accelerator. Target thicknesses range from 1000μg/cm 2 to 2500μg/cm 2 . The originality of this procedure consists in using the piezo-electric quartz for target thickness measurements and for temporary substrate. With this method, it is possible to measure the target thickness without geometrical errors and to suppress the effects of the molecular flux anisotropy. (Auth.)

  14. Determination of individual rare earth elements in Vietnamese monazite by radiochemical neutron activation analysis

    International Nuclear Information System (INIS)

    Nguyen Van Suc; Nguyen Mong Sinh

    1993-01-01

    Radiochemical neutron activation analysis (RNAA) has been applied for determination of rare earth elements (REE) in Vietnamese monazite. The chemical separation procedure used is based on the chromatographic elution of rare earth groups, after the separation of 233 Pa(Th) in irradiated monazite samples by coprecipitation with MnO 2 , the rare earth elements were retained by Biorad AG1 x 8 resin column in 10% 15.4M HNO 3 -90% methanol solution. The elution of heavy rare earth (HREE) and middle rare earth (MREE) groups was carried out with 10% 1M HNO 3 - 90% methanol and 10% 0.05M HNO 3 -90% methanol solution, respectively; while the light rare earths (LREE) were eluted from the column by 0.1M HNO 3 solution. The accuracy of the method was checked by the analysis of granodiorite GSP-I and the rare earth values were in good agreement. (author) 7 refs.; 3 tabs

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

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  16. Solvent extraction of rare earths from thiocyanate medium using N,N,N',N'-tetra-2-ethylhexyl diglycolamide

    International Nuclear Information System (INIS)

    Anitha, M.; Kotekar, M.K.; Singh, D.K.; Sharma, J.N.; Singh, H.

    2014-01-01

    TEHDGA (N,N,N',N'-tetra-2-ethylhexyl diglycolamide), a neutral extractant, has been explored for separation of Yttrium from other heavy rare earths (Er) from thiocyanate medium. Presence of 5%(v/v) isodecyl alcohol was found to be optimum to prevent third phase formation. Experimental variables such as TEHDGA concentration (0.05M-0.2M), thiocyanate concentration (0.01M-0.04M), aqueous pH, rare earth concentration (0.25g/L-5g/L), temperature (35℃-65℃), stripping reagents on extraction of rare earths were investigated. The extraction of rare earths increased with increase in TEHDGA concentration and the dependency of distribution ratio of rare earth on TEHDGA concentrations is shown. The slopes were analysed to be approximately 3 for all the rare earths. The effect of thiocyanate concentration on distribution ratio is depicted. Based on slope analysis technique, the extracted species was found to be RE(SCN) 3 .3TEHDGA. The distribution ratio values decreased, may possibly be due to decrease in free extractant concentration in the organic phase, from 8.4 to 0.1 for Y with increase in yttrium concentration in the range of 0.25g/L to 5g/L. The extraction of rare earth decreased with increase in temperature indicating exothermic in nature and the enthalpy change (ΔH) obtained for Y(III) was -14.27KJ/mol. Among stripping reagents studied, oxalic acid was efficient in quantitative stripping of rare earths from TEHDGA. The extraction efficiency for rare earths by TEHDGA increased with increase in atomic number: La< Ce< Pr< Nd< Sm< Y< Eu< Gd< Tb< Dy< Ho< Er< Tm< Lu irrespective of thiocyanate concentration. Separation factors between these metal ions were also evaluated. High separation factor of 6.4 for Er/Y pair at 0.03M thiocyanate has indicated the feasibility of using TEHDGA as extractant to separate Y from Er and other rare earths as an alternative for Aliquat 336-thiocyanate system developed in our laboratory

  17. Character of changes in the thermodynamic properties of alloyed melts of rare-earth metals with low-melting-point p- and d-metals

    International Nuclear Information System (INIS)

    Yamshchikov, L.F.; Zyapaev, A.A.; Raspopin, S.P.

    2003-01-01

    Published data on thermodynamic characteristics of lanthanides in liquid-metal melts of gallium, indium and zinc were systematized. The monotonous change from lanthanum to lutetium was ascertained for activity values and activity coefficients of trivalent lanthanides in the melts, which permits calculating the values for the systems of fusible metals, where no experimental data are available [ru

  18. 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.)

  19. Thermoelectric transport in rare-earth compounds

    International Nuclear Information System (INIS)

    Koehler, Ulrike

    2007-01-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Science.gov (United States)

    Ding, Kaihong

    2014-07-01

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

  2. 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.

  3. 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.

  4. 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.

  5. Synchrotron radiation studies of local structure and bonding in transition metal aluminides and rare earth transition metal magnetic nitrides. Final report, August 1, 1990--July 14, 1993

    International Nuclear Information System (INIS)

    Budnick, J.I.; Pease, D.M.

    1995-01-01

    The following areas of study are reported on: bonding and near neighbor force constants in NiAl, CoAl, FeAl via temperature dependent EXAFS; alloys formed when Fe or Ga is microalloyed into a NiAl matrix; EXAFS studies of nitrided versus non nitrided Y 2 Fe 17 ; and transition metal x-ray spectra as related to magnetic moments

  6. 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%.

  7. 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.

  8. Bioaccumulation of Heavy Metals

    African Journals Online (AJOL)

    komla

    acute toxicity and sublethal chronic action the devastating effects that the accumulation - including ... the laboratory and kept in holding glass (a) Copper as CuSO,.5H,0 ... from 2 psu to 21 psu) depending on time of The choice of heavy metals for this s year. ... serving as substrate and food source for Salinity of test media.

  9. Fertiliser characterisation: Major, trace and rare earth elements

    International Nuclear Information System (INIS)

    Otero, N.; Vitoria, L.; Soler, A.; Canals, A.

    2005-01-01

    In recent years, there has been increasing concern regarding the chemical impact of agricultural activities on the environment so it is necessary to identify contaminants, and/or characterise the sources of contamination. In this study, a comprehensive chemical characterisation of 27 fertilisers of different types used in Spain has been conducted; major, minor and trace elements were determined, including rare earth elements. Results show that compound fertilisers used for fertigation or foliar application have low content of heavy metals, whereas fertilisers used for basal and top dressing have the highest content of both REE and other heavy metals. REE patterns of fertilisers have been determined in order for them to be used as tracers of fertilisers in future environmental studies. Furthermore in this work REE patterns of fertilisers are used as tracers of the source of phosphate in compound fertilisers, distinguishing between phosphorite and carbonatite derived fertilisers. Fertilisers from carbonatites have higher contents of REE, Sr, Ba and Th whereas fertilisers from phosphorites have higher contents of metals of environmental concern, such as Cd, U and As; and the sum of the heavy metals is higher. Some of the analysed fertilisers have Cd concentrations that exceed maximum values established in some countries and can be expected to produce long-term soil accumulation. Furthermore, other elements such as U, As and Cr are 10-50 times higher in concentration than those of Cd, but there is no legislation regarding them, therefore it is necessary to regulate fertiliser compositions in order to achieve environmental protection of soils and waters

  10. (17) ACCUMULATION OF HEAVY METAL

    African Journals Online (AJOL)

    Adeyinka Odunsi

    Spectrophotometer (AAS) 2ID using their respective lamp and wavelengths. Calculation ... (Table 2). Concentration of heavy metals in the cassava. Lead and chromium were not significantly ..... Market basket survey for some heavy metals in ...

  11. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  12. Rare earth industries: Strategies for Malaysia

    International Nuclear Information System (INIS)

    2011-01-01

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

  13. Evaluation and distribution of metals, trace elements and rare earths in sediments profiles of Promissão Reservoir, Sao Paulo state, Brazil, by INAA

    International Nuclear Information System (INIS)

    Angelini, Matheus; Rocha, Flavio R.; Fávaro, Deborah I.T.; Franklin, Robson L.

    2017-01-01

    The concentration of elements at two points in the reservoir (1 and 3) was evaluated. Two profiles of fractionated sediments were collected in the field every 2.5 cm, generating 14 and 20 fractions, respectively, according to their depths (35 and 50 cm). The concentrations of the elements: As, Ba, Br, Ca, Co, Cr, Cs, Fe, Hf, K, Na, Rb, Sb, Sc, Ta, Th, U, Zn and the rare earth elements (Ce, Eu, Gd, La, Lu, Nd, Sm, Tb and Yb) were determined using the technique of Instrumental Neutron Activation Analysis (INAA). The validation of the methodology was done through the analysis of certified reference materials. The values of the North American Shale Composite (NASC) were used as reference values for calculation of Enrichment Factor (FE) and Geoacumulation Index (IGeo), tools used to evaluate pollution levels. The concentration of the As, Cr and Zn elements was also compared with the Guideline values TEL (Treshold Effect Level) and PEL (Probable Effect Level), values that provide concentration ranges for these elements indicating the presence or not of probable effects in aquatic biota from these concentrations

  14. Evaluation of the concentrations of rare earth elements, metals and traces in sediments of the Graminha Reservoir, São Paulo, SP, Brazil by Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Junqueira, Lucas S.; Fávaro, Déborah I.T.; Silva, Sharlleny A.

    2017-01-01

    Sediment profiles were collected in the Graminha (Caconde) supply reservoir, SP, in Aug / 2014 (points 1 and 4). The analytical technique of Neutral Activation with Instrumental Neutrons (INAA) was used and the determined elements were: As, Ba, Br, Ca, Co, Cr, Cs, Fe, Hf, K, Na, Rb, Sb, Ta, Th, U and Zn and the rare earth elements (ETRs) (Ce, Eu, La, Lu, Nd, Sm, Sc, Tb and Yb). The concentration values for the elements As, Cr and Zn were compared to the concentration guideline values (TEL and PEL) established by CCME (Canada) and adopted by CETESB. The sediments were classified as of good or optimal quality, for these 3 elements. The values found in the last slices of profile 1 (depth 90 cm) were taken as baseline values and from these values, the enrichment factors (FE) and the Geoacumulation Index (IGeo) were calculated. Values of FE> 1.5 were found, mainly, for the ETRs, U and Th, in both points, indicative of presence of anthropic contribution. The IGeo values confirmed FE values, with values of 1

  15. Squeezing clathrate cages to host trivalent rare-earth guests

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States); He, Yuping [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Mordvinova, Natalia E. [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Lebedev, Oleg [Laboratoire CRISMAT, ENSICAEN, CNRS UMR (France); Kovnir, Kirill [Iowa State Univ., Ames, IA (United States). Department of Chemistry; Ames Lab., Ames, IA (United States)

    2017-11-01

    Strike difference of the trivalent rare-earth cations from their alkali and alkaline-earth peers is in the presence of localized 4f-electrons and strong spin-orbit coupling. Placing trivalent rare-earth cations inside the fullerene molecules or in between the blocks of itinerant magnetic intermetallics gave rise to plethora of fascinating properties and materials. A long-time missing but hardly desired piece is the semiconducting or metallic compound where rare-earth cations are situated inside the oversized polyhedral cages of three-dimensional framework. In this work we present a synthesis of such compounds, rare-earth containing clathrates Ba8-xRxCu16P30. The unambiguous proofs of their composition and crystal structure were achieved by a combination of synchrotron powder diffraction, time-of-flight neutron powder diffraction, scanning-transmission electron microscopy, and electron energy-loss spectroscopy. Our quantum-mechanical calculations and experimental characterizations show that the incorporation of the rare-earth cations significantly enhances the hole mobility and concentration which results in the drastic increase in the thermoelectric performance.

  16. Effects of the presence of heavy rare earths on the stabilization of the zirconia ceramics - Yttria; Efeito da presenca de terras raras pesadas na estabilizacao das fases de ceramicas de zirconia - itria

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, D.R.R.; Fancio, E.; Menezes, C.A.B.; Ussui, V.; Bressiani, A.H.A.; Lima, N.B.; Paschoal, J.O.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: drlazar@net.ipen.br

    2000-07-01

    The use of Yttria concentrates has been proposed to substitute the high purity Yttria in the zirconia stabilization. The elements terbium, dysprosium, holmium, erbium and ytterbium, classified as heavy rare earths, are the main impurities in these concentrates, due to their presence in yttrium ores. Besides that, the chemical similarities of these elements need the utilization of complex purification techniques. Considering the importance of the employed dopant on zirconia crystallization, this work shows the quantitative phases analysis of powders and ceramics of stabilized zirconia doped with 3 and 9 mol % of high purity Yttria and with a 85 wt % Yttria concentrate. This determination was performed using the Rietveld refinement of the X-ray diffraction data. The powders were synthesized by the hydroxides coprecipitation route, which includes treatments with ethanol and butanol, drying, calcination at 800 deg C for 1 hour and milling in a ball mill and in an attrition mill. The ceramics pellets were pressed uniaxially and sintered at 1550 deg C for 1 hour. The powders and sintered pellets were also characterized by X-ray fluorescence analysis, laser diffraction, gas adsorption (B.E.T.), scanning electron microscopy and determination of apparent density by the Archimedes method. The results showed the same stabilization behavior when it was employed high purity Yttria and a concentrate of this oxide. It was also observed the predominating formation of tetragonal and cubic phases when the dopant concentration is 3 and 9 mol %, respectively. (author)

  17. Redox reactions in rare earth chloride molten electrolytes

    International Nuclear Information System (INIS)

    Khokhlov, V.A.; Novoselova, A.V.; Nikolaeva, E.V.; Tkacheva, O.Yu.; Salyulev, A.B.

    2007-01-01

    Rare earth (REM, Ln) solutions in chloride melts including MCI+LnCl 3 mixtures, where M - alkali metals, were investigated by potentiometry, voltammetry, conductometry in wide concentration and temperature intervals. Findings present complete and trusty information on the valent state of rare earths, structure and composition of complex ions affecting essentially on properties of electrolytes. It is demonstrated that the coexistence of rare earth ions with different oxidation level formed as a result of possible redox reactions: 2Ln 3+ + Ln ↔3Ln 2+ , Ln 2+ + Ln↔2Ln + and nM + + Ln↔nM + Ln n+ appears sharply in thermodynamic and transport properties of molten Ln-LnCl 3 and Ln-LnCl 3 -MCl systems [ru

  18. Spectrophotometric determination of rare earths in binary mixtures

    International Nuclear Information System (INIS)

    Krasnova, A.V.; Shvarev, V.S.

    1978-01-01

    The possibility was investigated of using the reaction with brompyrogallol red (BPR) (dibrompyrogallosulfophthalein) for analyzing binary mixtures of rare earth metals close in ordinal numbers (La-Y, La-Eu, La-Sm, La-Nd, Nd-Y, Nd-Eu). Heavy REM are masked by nitrile-acetic acid (NAA). The experimental design method was used to determine optimum conditions. The optimizing parameters were the optical density measured with respect to water and the amount of the component bound into the complex. It was found that optimum conditions for the analysis of investigated mixtures differ only in the amount of NAA necessary to mask the heavy element [NAA]/[Sm 3+ ]=4; [NAA]/[Eu 3+ ]=5; [NAA]/Nb 3+ ]=10; [NAA]/[Y 3+ ]=2.5. The optimum acidity and the amount of BPR are always the same: pH 6.5; [BPR]/[La 3+ ]=[BPR]/[Nd 3+ ]=4. The given method for analyzing binary mixtures of lanthanoids surpasses considerably in sensitivity the methods based on intrinsic absorption spectra, while retaining the same reproducibility

  19. Supramolecular structures constructed from three novel rare earth ...

    Indian Academy of Sciences (India)

    Supramolecular structures constructed from three novel rare earth metal complexes. HUAZE DONGa,∗, XIAOJUN FENGb,∗, XIA LIUc, BIN ZHENGa, JIANHONG BIa, YAN XUEa,. SHAOHUA GOUd and YANPING WANGa. aDepartment of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.

  20. Rare earth ion controlled crystallization of mica glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Garai, Mrinmoy; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in

    2016-09-05

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO{sub 2}, Nd{sub 2}O{sub 3}, Sm{sub 2}O{sub 3} and Gd{sub 2}O{sub 3} doped K{sub 2}O−MgO−B{sub 2}O{sub 3}−Al{sub 2}O{sub 3}−SiO{sub 2}−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm{sup −3}) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T{sub g}) and crystallization temperature (T{sub c}). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg{sub 3}(AlSi{sub 3}O{sub 10})F{sub 2} by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10{sup −6}/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque

  1. Rare earth ion controlled crystallization of mica glass-ceramics

    International Nuclear Information System (INIS)

    Garai, Mrinmoy; Karmakar, Basudeb

    2016-01-01

    In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO_2, Nd_2O_3, Sm_2O_3 and Gd_2O_3 doped K_2O−MgO−B_2O_3−Al_2O_3−SiO_2−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm"−"3) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T_g) and crystallization temperature (T_c). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg_3(AlSi_3O_1_0)F_2 by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10"−"6/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque fluorophlogopite mica glass-ceramics by single-step heat treatment. • Nanocrystalline glass

  2. Heavy metals in our foodstuffs

    Energy Technology Data Exchange (ETDEWEB)

    1983-11-01

    The special group ''chemistry of food and forensic chemistry'' of the Association of German Analytical Chemists in Munich in 1983 issued a statement on that subject. The publication points out how heavy metals (examples: lead, cadmium and mercury) make their way into the foodstuffs, how many heavy metals are contained in our foodstuffs, which heavy metals are indispensable minerals and which aren't, and which heavy metals are ingested with food. It concludes by discussing how heavy metal contamination of our food can be prevented.

  3. Chemical analysis of rare earth elements

    International Nuclear Information System (INIS)

    Tsukahara, Ryoichi; Sakoh, Takefumi; Nagai, Iwao

    1994-01-01

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

  4. Rare earth oxyhydrides and preparation process

    International Nuclear Information System (INIS)

    Diaz, H.

    1986-01-01

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

  5. Process for lead removal from rare earth

    International Nuclear Information System (INIS)

    Bollat, A.; Sabot, J.L.

    1987-01-01

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

  6. Rare Earth Elements Distribution in Beryl

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  7. 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

  8. Preparation and characteristics of various rare earth nitrides

    International Nuclear Information System (INIS)

    Imamura, H.; Imahashi, T.; Zaimi, M.; Sakata, Y.

    2008-01-01

    Active nanocrystalline nitrides of EuN and YbN with high surface areas were successfully prepared by the thermal decomposition of the rare earth amides (Eu(NH 2 ) 2 , Yb(NH 2 ) 2 and Yb(NH 2 ) 3 ). For the preparation of CeN, PrN and NdN, the direct reaction of the rare earth metals with ammonia was extensively studied to determine optimal conditions. In the reaction of rare earth metals with ammonia, hydrides besides the nitrides were competitively formed. The reaction conditions such as temperatures and ratios of ammonia to rare earth metal were crucial in preferential formation of nitride. The nanocrystalline YbN and EuN readily absorbed large amounts of ammonia even at room temperature upon contact with ammonia (13.3 kPa). The absorbed ammonia existed in at least two forms on/in the nitride; the one was surface-adsorbed ammonia and the other ammonia absorbed in the nitride in a decomposed state. The properties of ammonia absorbed by the nitride were further evaluated by temperature-programmed desorption (TPD), FT-IR and XRD techniques

  9. A comparison between rare earth and transition metals working as magnetic materials in an AMR refrigerator in the room temperature range

    International Nuclear Information System (INIS)

    Aprea, C.; Greco, A.; Maiorino, A.; Masselli, C.

    2015-01-01

    This paper describes a two-dimensional (2D) multiphysics model of a packed bed regenerator made of magnetocaloric material. The regenerator operates as a refrigerant for a magnetic refrigerator operating at room temperature on the strength of an active magnetic regenerator (AMR) cycle. The model is able to simulate the thermofluidodynamic behavior of the magnetocaloric material and the magnetocaloric effect of the refrigerant. The model has been validated by means of experimental results. Different magnetic materials have been tested with the model as refrigerants: pure gadolinium, second order phase magnetic transition Pr_0_._4_5Sr_0_._3_5MnO_3 and first order phase magnetic transition alloys Gd_5(Si_xGe_1_−_x)_4, LaFe_1_1_._3_8_4Mn_0_._3_5_6Si_1_._2_6H_1_._5_2, LaFe_1_1_._0_5Co_0_._9_4Si_1_._1_0 and MnFeP_0_._4_5As_0_._5_5. The tests were performed with fixed fluid flow rate (5 l/min), AMR cycle frequency (1.25 Hz) and cold heat exchanger temperature (288 K) while the hot heat exchanger temperature was varied in the range 295–302 K. The results, generated for a magnetic induction which varies from 0 to 1.5 T, are presented in terms of temperature span, refrigeration power and coefficient of performance. From a global point of view (performances and cost), the most promising materials are LaFeSi compounds which are really cheaper than rare earth compounds and they give a performance sufficiently higher than gadolinium. - Graphical abstract: • Active Magnetic Refrigeration (AMR) cycle; • First Order Transition magnetic materials (FOMT); • Second Order Transition magnetic materials (SOMT). - Highlights: • Comparison between different magnetic materials. • 2D model of an Active Magnetic Regenerative refrigeration cycle. • Validation of the model with experimental data. • Gd_5(Si_xGe_1_−_x)_4 is the most performant magnetic material. • The most promising are LaFeSi compounds which are cheaper and they give high performances.

  10. Separation of Rare Earths from Uranium and Thorium

    International Nuclear Information System (INIS)

    Krebs, Damien

    2014-01-01

    Greenland Minerals and Energy - Key Highlights – A unique world class mining project: 1. World-class, large scale development project: • Economically robust, proven technology, large-scale, long life production of rare earths concentrate and uranium; • Large JORC resource base to produce ~7kt HREO, 37kt LREO & 3Mlbs U_3O_8 per annum over 30 year mine life; • Ideally located near international airport, existing towns and potential hydro-electric power source. 2. Very attractive commodity portfolio: • Heavy rare earths and uranium are both recognised as strategically important commodities for the future; • Rare earths market characterised by limited capacity and increasing demand (particularly Dy, Nd, Tb, Eu and Y). 3. Strong management and technical team: • Experienced management team with proven track record; • Well-respected and knowledgeable technical/project team in place with exceptional local expertise. 4. Highly advantageous ore-type, makes for simple cost-effective processing, highly scalable production: • High upgrade through beneficiation brings optionality to Kvanefjeld project; • Leaching can be done in Greenland, or owing to the high-grade concentrate, can be shipped to other locations; • Allows to single concentrator in Greenland, multiple refineries/partners globally. 5. Globally significant, long life, low cost, multi-commodity asset: • Company to become one of the largest producers of rare earths globally and a significant U_3O_8 mine; • Potential to supply >20% of global critical (including heavy) rare earth element demand; • Company has low cost of production due to multiple by-product opportunities. 6. Low political risk: • Stable, low-risk operating environment with government looking to develop new industries and employment; • GME fully permitted to evaluate the project, exploration licence now includes radioactive elements; • Management and board have a solid working relationship with the government and are

  11. Isopiestic determination of the activity coefficients of some aqueous rare earth electrolyte solutions at 250C. I. The rare earth chlorides

    International Nuclear Information System (INIS)

    Spedding, F.H.; Weber, H.O.; Saeger, V.W.; Petheram, H.H.; Rard, J.A.; Habenschuss, A.

    1976-01-01

    The osmotic coefficients of the aqueous trichlorides of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y were determined from 0.1 M to saturation at 25 0 C. Semiempirical least-squares equations were obtained for the osmotic coefficients as a function of molality and these equations were used to calculate water activities and mean molal activity coefficients. The water activities of the light rare earth chlorides at constant molalities are higher than for the heavy rare earths, while the mean molal activity coefficients are larger for the heavy rare earths than for the light ones. The above effects are discussed in terms of changes in the cationic radii and hydration of the rare earth ions

  12. Purification process for aqueous solutions of rare earths by liquid-liquid extraction

    International Nuclear Information System (INIS)

    Rollat, A.; Sabot, J.L.; Burgard, M.; Delloye, T.

    1986-01-01

    Alkaline earth metals are removed by liquid-liquid extraction between on aqueous nitric phase of impure rare earth compounds and an organic phase of polyether (crown ether). This process is particularly suited to removal of Ca, Ba and Ra contained in nitric solutions of rare earths [fr

  13. Rare Earths and Clean Energy: analyzing China's upper hand

    International Nuclear Information System (INIS)

    Seaman, J.

    2010-01-01

    An ominous but avoidable resource crunch in the so-called 'rare earth elements' is now threatening the development of a number of key industries from energy to defense to consumer electronics. As key components in the latest generation of technologies, including specialized magnets for windmills and hybrid cars, lasers for range finders and 'smart' munitions, and phosphors for LCD screens, demand for these rare metals is expected to grow rapidly in the years to come. But decades of under-investment in the mining and separation of these elements across the globe has left the industry ill-prepared to meet thi s growing demand. Over the years, only China has recognized the strategic significance of these resources and has succeeded in gaining a near monopoly on production, currently churning out 97% of the world' s rare earth oxides. Faced with problems of its own, and eager to use its resource advantage to master higher levels of value-added production of rare earth-dependent products, China has increasingly limited the rest of the world's access to these raw materials. This only complicates what was already projected to be a problematic resource shortage. This issue demands a higher quality of public debate. Rare earth consuming countries outside of China have only recently become aware of their dependence and started to take stock of the risks. Time is of the essence. Bringing new supplies online to meet growing demand is a long, complicated and risky process but is nevertheless necessary to ensure the development of high tech industries, notably clean energy. Accessible reserves of rare earths do exist outside of China and mitigating the effects of the looming shortage requires opening up these reserves to production. Yet, as the Chinese experience attests, there are substantial risks to the environment associated with mining and separating rare earths. Care must be taken to ensure responsible mining practices across the globe. Longer-term solutions, such as

  14. Development of electrolytic process in molten salt media for light rare-earth metals production. The metallic cerium electrodeposition; Desenvolvimento de processo de eletrolise em meio de sais fundidos para a producao de metais de terras-raras leves. A obtencao do cerio metalico

    Energy Technology Data Exchange (ETDEWEB)

    Restivo, T A.G.

    1994-12-31

    The development of molten salt process and the respective equipment aiming rare-earth metals recovery was described. In the present case, the liquid cerium metal electrodeposition in a molten electrolytes of cerium chloride and an equimolar mixture of sodium and potassium chlorides in temperatures near 800{sup C} was studied. Due the high chemical reactivity of the rare-earth metals in the liquid state and their molten halides, an electrolytic cell was constructed with controlled atmosphere, graphite crucibles and anodes and a tungsten cathode. The electrolytic process variables and characteristics were evaluated upon the current efficiency and metallic product purity. Based on this evaluations, were suggested some alterations on the electrolytic reactor design and upon the process parameters. (author). 90 refs, 37 figs, 20 tabs.

  15. Phase extraction equilibria in systems rare earth (3) nitrates-ammonium nitrate-water-trialkylmethylammonium nitrate

    International Nuclear Information System (INIS)

    Pyartman, A.K.; Kopyrin, A.A.; Puzikov, E.A.

    1995-01-01

    The distribution of rare earth metals (3) between aqueous and organic phases in the systems rare earth metal (3) (praseodymium-lutetium (3), yttrium (3)) nitrate-ammonium nitrate-water-trialkylmethylammonium (kerosene diluent nitrate has been studied. It is shown that in organic phase di- and trisolvates of metals (3) with tralkylmethylammonium nitrate are formed. The influence of concentration of rare earth metal (3) nitrate and ammonium nitrate on the values of extraction concentrational constants has been ascertained: they decrease with increase in the ordinal number of lanthanide (3). 11 refs., 4 figs. 1 tab

  16. Thermochemistry of rare-earth trifluorides

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  17. Recovery of rare earths from red mud

    International Nuclear Information System (INIS)

    Bautista, R.G.

    1992-01-01

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

  18. Rare Earth Element Phases in Bauxite Residue

    Directory of Open Access Journals (Sweden)

    Johannes Vind

    2018-02-01

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

  19. Rare earth metal bis(silylamide) complexes bearing pyridyl-functionalized indenyl ligand: synthesis, structure and performance in the living polymerization of L-lactide and rac-lactide.

    Science.gov (United States)

    Wang, Yibin; Lei, Yinlin; Chi, Shuhui; Luo, Yunjie

    2013-02-07

    Amine elimination of rare earth tris(silylamide) complexes Ln[N(SiHMe(2))(2)](3)(THF)(2) (Ln = La, Sm, Er, Lu) with 1 equiv. of the pyridyl-functionalized indenyl ligand C(9)H(7)CMe(2)CH(2)C(5)H(4)N-α afforded a series of neutral mono-indenyl-ligated rare earth metal bis(silylamide) complexes (C(9)H(6)CMe(2)CH(2)C(5)H(4)N-α)Ln[N(SiHMe(2))(2)](2) (Ln = La (1), Sm (2), Er (3), Lu (4)) in 83-87% isolated yields. Reaction of La[N(SiHMe(2))(2)](3)(THF)(2) with 2 equivalents of C(9)H(7)CMe(2)CH(2)C(5)H(4)N-α provided the neutral bis(indenyl) lanthanum mono(silylamide) complex (C(9)H(6)CMe(2)CH(2)C(5)H(4)N-α)(2)LaN(SiHMe(2))(2) (5). These complexes were characterized by elemental analysis, FT-IR and NMR (except for 3 for the strong paramagnetic property of the central metal). X-ray single crystal structural diffraction showed that 1-4 are isostructural and the central metals are four-coordinated by one indenyl ring, one nitrogen atom from the pendant pyridyl group, and two amide groups to form a distorted tetrahedral geometry; while the central metal in 5 is five-coordinated by two indenyl rings, two nitrogen atoms from the pendant pyridyl groups, and one amide group to adopt a distorted pyramidal geometry, if the indenyl ring is regarded as occupying an independent vertex. The monoanionic pyridyl-functionalized indenyl ligand is bonded to the central metal in η(5)/κ(1) constrained geometry configuration (CGC) mode. 1-4 are highly active for the ring-opening polymerization of L-lactide and rac-lactide. In the presence of 2 equivalents of benzyl alcohol, 1 shows high activity toward L-lactide and rac-lactide in a living fashion.

  20. Rare earth silicide nanowires on silicon surfaces

    International Nuclear Information System (INIS)

    Wanke, Martina

    2008-01-01

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

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  3. Thermodynamics of rare earths in steelmaking

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  4. 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

  5. 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

  6. Mammography with rare earth intensifying screens

    International Nuclear Information System (INIS)

    Maurer, H.J.; Goos, F.

    1987-01-01

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

  7. Contribution to the study of rare earth separation by ion exchange, using ammonium lactate

    International Nuclear Information System (INIS)

    Gratot, I.

    1958-01-01

    Using the technique of chromatography on a column of Dowex 50 resin, heated to 87 deg. C, we have studied the separation of rare earths (from holmium to praseodymium) which may be produced with the cyclotron by heavy ions, α or protons. From an ammonium lactate solution M at pH 5, separations are carried out by varying the dilution as a function of the quantity of the target rare earth and of its position during elution. When weighable quantities of the rare earth (more than 5 mg) appear towards the end of the elution, the separation is little affected this case approaches that of a tracer mixture of rare earths; if on the other hand weighable quantities of the rare earth are washed through at the beginning of the chromatogram, the dilution must be adjusted in order to obtain a good separation. (author) [fr

  8. An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

    Science.gov (United States)

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

    2015-07-06

    Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stiehler, Martin

    2012-02-03

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

  10. Heavy metals and soil microbes

    NARCIS (Netherlands)

    Giller, K.E.; Witter, E.; McGrath, S.

    2009-01-01

    The discovery in the early 1980s that soil microorganisms, and in particular the symbiotic bacteria Rhizobium, were highly sensitive to heavy metals initiated a new line of research. This has given us important insights into a range of topics: ecotoxicology, bioavailability of heavy metals, the role

  11. 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.

  12. Crystal chemistry and magnetic properties of ternary rare earth sulfides

    International Nuclear Information System (INIS)

    Plug, C.M.; Rijksuniversiteit Leiden

    1977-01-01

    The results of magnetic measurements on two groups of ternary rare earth sulphides are described, the MLnS 2 (M=Li, Na, K) type of compounds and the series Ln 2 ZrS 5 , where Ln denotes one of the rare earths. None of these compounds is metallic, excluding the possibility of RKKY-interaction. In chapter II a survey of the relevant theory on magnetic properties and crystal field splitting is given. In spite of the similarity in chemical properties of the rare earths, the crystal chemistry of their compounds is rather complex. This is due to the lanthanide contraction. The third chapter deals with the description and classification of the numerous crystal structures of both ternary and binary rare earth sulphides that have been observed. Rather simple relations between various structures are presented using a new method of structure classification. The magnetic interactions expected to be based on superexchange via the anions, which is usually very structure dependent. Experiments to study the crystallographic ordering, applying both X-ray and electron diffraction methods and the results of the magnetic measurements on the compounds MLnS 2 are reported in chapter IV. The compounds Ln 2 ZrS 5 are candidates for a systematic study of the variation of the magnetic properties along the rare earth series. The results of magnetic measurements on these compounds are presented in chapter V, combined with the results of specific heat measurements. Also the magnetic structure of two representatives, Tb 2 ZrS 5 and Dy 2 ZrS 5 , determined by neutron diffraction experiments below the ordering temperature, is reported

  13. Leaching Process of Rare Earth Elements, Gallium and Niobium in a Coal-Bearing Strata-Hosted Rare Metal Deposit—A Case Study from the Late Permian Tuff in the Zhongliangshan Mine, Chongqing

    Directory of Open Access Journals (Sweden)

    Jianhua Zou

    2017-05-01

    Full Text Available The tuff, a part of coal-bearing strata, in the Zhongliangshan coal mine, Chongqing, southwestern China, hosts a rare metal deposit enriched in rare earth elements (REE, Ga and Nb. However, the extraction techniques directly related to the recovery of rare metals in coal-bearing strata have been little-studied in the literature. The purpose of this paper is to investigate the extractability of REE, Ga and Nb in the tuff in the Zhongliangshan mine using the alkaline sintering-water immersion-acid leaching (ASWIAL method. The results show that ASWIAL can separate and extract REE, Ga and Nb effectively under the optimized conditions of calcining at 860 °C for 0.5 h with a sample to sintering agent ratio of 1:1.5, immersing at 90 °C for 2 h with 150 mL hot water dosage, and leaching using 4 mol/L HCl at 40 °C for 2 h with a liquid-solid ratio of 20:1 (mL:g. The final leaching efficiencies of REE and Ga are up to 85.81% and 93.37%, respectively, whereas the leaching efficiency of Nb is less than 1%, suggesting the high concentration of Nb in the leaching residue, which needs further extraction.

  14. Physical and electrical characteristics of AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors with rare earth Er2O3 as a gate dielectric

    International Nuclear Information System (INIS)

    Lin, Ray-Ming; Chu, Fu-Chuan; Das, Atanu; Liao, Sheng-Yu; Chou, Shu-Tsun; Chang, Liann-Be

    2013-01-01

    In this study, the rare earth erbium oxide (Er 2 O 3 ) was deposited using an electron beam onto an AlGaN/GaN heterostructure to fabricate metal-oxide-semiconductor high-electron-mobility transistors (MOS–HEMTs) that exhibited device performance superior to that of a conventional HEMT. Under similar bias conditions, the gate leakage currents of these MOS–HEMT devices were four orders of magnitude lower than those of conventional Schottky gate HEMTs. The measured sub-threshold swing (SS) and the effective trap state density (N t ) of the MOS–HEMT were 125 mV/decade and 4.3 × 10 12 cm −2 , respectively. The dielectric constant of the Er 2 O 3 layer in this study was 14, as determined through capacitance–voltage measurements. In addition, the gate–source reverse breakdown voltage increased from –166 V for the conventional HEMT to –196 V for the Er 2 O 3 MOS–HEMT. - Highlights: ► GaN/AlGaN/Er 2 O 3 metal-oxide semiconductor high electron mobility transistor ► Physical and electrical characteristics are presented. ► Electron beam evaporated Er 2 O 3 with excellent surface roughness ► Device exhibits reduced gate leakage current and improved I ON /I OFF ratio

  15. Adducts of rare earth tris-acetylacetonates with dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Dzyubenko, N.G.; Kalenichenko, Yu.V.; Martynenko, L.I.

    1988-01-01

    Adducts of rare earth and yttrium (r.e.e., M) acetylacetonates with dimethyl sulfoxide (DMSO), MA 3 xnDMSO are synthesized. The acetylacetonates of light r.e.e. (M=La-Tb) are shown by different physico-chemical methods to form diadducts of the MA 3 x2DMSOxH 2 O composition, where A - -acetylacetonate-ion, and the acetyl-acetonates of heavy r.e.e. (M=Dy-Lu, Y)-monoadducts MA 3 xDMSO. The estimation of adduct thermal stability is carried out using the values of seeming activation energy of their thermal degradation. Monoadducts are shown to give volatile forms of rare earth acetylacetonates during heating in vacuum, and diadducts do not form volatile forms of acetylacetonates

  16. Heavy metal sorption by microalgae

    International Nuclear Information System (INIS)

    Sandau, E.; Sandau, P.; Pulz, O.

    1996-01-01

    Viable microalgae are known to be able to accumulate heavy metals (bioaccumulation). Against a background of the increasing environmental risks caused by heavy metals, the microalgae Chlorella vulgaris and Spirulina platensis and their potential for the biological removal of heavy metals from aqueous solutions were taken as an example for investigation. Small-scale cultivation tests (50 l) with Cd-resistant cells of Chlorella vulgaris have shown that approx. 40% of the added 10 mg Cd/l was removed from the solution within seven days. At this heavy metal concentration sensitive cells died. Non-viable microalgae are able to eliminate heavy metal ions in a short time by biosorption in uncomplicated systems, without any toxicity problems. Compared with original biomasses, the sorption capacity of microalgal by-products changes only insignificantly. Their low price makes them economical. (orig.)

  17. Neutron diffraction search for the charge density waves in early rare earth metal deuterides RD/sub 3/ (R = La, Ce)

    Energy Technology Data Exchange (ETDEWEB)

    Alikhanov, R A; Buzin, V I; Kulikov, N I [AN SSSR, Moscow. Inst. Fiziki Vysokikh Davlenij; Kost, M E [Institute of General and Inorganic Chemistry, Academy of Sciences of the USSR, Moscow (USSR); Sikora, W [Joint Inst. for Nuclear Research, Dubna (USSR); Smirnov, L S [Institute of Theoretical and Experimental Physics, Moscow (USSR)

    1984-08-01

    The results of neutron diffraction measurements performed on CeDsub(x) near the trihydride composition MeD/sub 3/ at room temperature and on LaDsub(2.9) at liquid nitrogen and room temperatures are presented. Superstructure reflections have been found. The system of additional reflections in lanthanum deuteride is different from that in cerium deuteride. The concentration and temperature boundaries for the transformed phases are reported. The experimental results are discussed on the basis of Kulikov's excitonic dielectric model for metal-to-semiconductor phase transitions. The determination of crystal structures from experimental neutron diffraction patterns is discussed.

  18. Rare earths production and marketing opportunities

    International Nuclear Information System (INIS)

    Falconnet, P.G.

    1988-01-01

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

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

    Science.gov (United States)

    Sellmyer, D. J.; Nafis, S.

    1985-04-01

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

  20. Rare Earth Borohydrides—Crystal Structures and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Christoph Frommen

    2017-12-01

    Full Text Available Rare earth (RE borohydrides have received considerable attention during the past ten years as possible hydrogen storage materials due to their relatively high gravimetric hydrogen density. This review illustrates the rich chemistry, structural diversity and thermal properties of borohydrides containing RE elements. In addition, it highlights the decomposition and rehydrogenation properties of composites containing RE-borohydrides, light-weight metal borohydrides such as LiBH4 and additives such as LiH.

  1. Complexing in aqueous solutions of rare earth n-aminobenzoates

    International Nuclear Information System (INIS)

    Efremova, G.I.; Buchkova, R.T.; Lapitskaya, A.V.; Pirkes, S.B.

    1977-01-01

    Complexing in the system ''ion of a rare-earth metal - n-aminobenzoic acid'' has been investigated by the pH-metric method in the pH range of 3.5-5.5. In the La-Eu series, the stability of n-aminobenzoate complexes increases and attains the maximum value in the complex Eu (lg Ksub(st)=2.66). In the Gd-Lu series the stability of the complex particles decreases monotonically

  2. Rare earth elements and oxides in liquid phase epitaxy

    Czech Academy of Sciences Publication Activity Database

    Procházková, Olga; Grym, Jan; Zavadil, Jiří; Kopecká, M.

    2006-01-01

    Roč. 100, č. 8 (2006), s. 640-- ISSN 0009-2770. [Sjezd chemických společností /58./. Ústí nad Labem, 04.09.2006-08.09.2006] R&D Projects: GA ČR(CZ) GA102/06/0153 Institutional research plan: CEZ:AV0Z20670512 Keywords : semiconductor technology * rare earth metals Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.431, year: 2006

  3. Rare Earth Elements: A Tool for Understanding the Behaviour of Trivalent Actinides in the Geosphere

    International Nuclear Information System (INIS)

    Buil, Belen; Gomez, Paloma; Garralon, Antonio; Turrero, M. Jesus

    2007-01-01

    Rare earth element (REE) concentrations have been determined in groundwaters, granite and fracture fillings in a restored uranium mine. The granitoids normalized REE patterns of groundwaters show heavy rare earth elements (HREE)-enrichment and positive Eu anomalies. This suggests that the REE are fractionated during leaching from the source rocks by groundwaters. Preferential leaching of HREE would be consistent with the greater stability of their aqueous complexes compared to those of the light rare earth elements (LREE), together with the dissolution of certain fracture filling minerals, dissolution/alteration of phyllosilicates and colloidal transport. (authors)

  4. MOCVD and ALD of rare earth containing multifunctional materials. From precursor chemistry to thin film deposition and applications

    International Nuclear Information System (INIS)

    Milanov, Andrian Petrov

    2010-01-01

    The present thesis deals with the development of metal-organic complexes of rare elements. They should be used as novel precursors for the production of rare earth thin films by metal-organic chemical vapor deposition (MOCVD) and Atomic Layer Deposition (ALD). Within the work two precursor classes were examined, the tris-Malonato-complexes as well as the tris-Guanidinato-complexes of a series of rare earth metals. The latter showed excellent properties regarding to their volatility, their thermal stability, the defined decomposition and high reactivity towards water. They have been successfully used as precursors for the MOCVD of rare earth oxide layers. By using of a gadolinium guanidinate it could also be shown that the rare earth guanidinates are promising precursors for ALD of rare earth oxide and MOCVD of rare earth nitride layers. [de

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

    Directory of Open Access Journals (Sweden)

    A. M. Samuel

    2018-01-01

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

  6. Toxicity of heavy metals in the environment

    National Research Council Canada - National Science Library

    Oehme, F.W

    1978-01-01

    ... as the fundamental mechanisms of toxicity resulting from heavy metal chemicals. The more common toxic heavy metals, along with their biochemistry and associated clinical syndromes, are then described...

  7. Rare earth mineralogy of the Olympic Dam Cu-U-Au-Ag deposit, South Australia

    International Nuclear Information System (INIS)

    Lottermoser, B.G.; Day, A.

    1993-01-01

    Rare earth elements (REE) and yttrium accompany uranium and copper mineralisation within the polymetallic Olympic Dam deposit. The light and heavy rare earths tend to occur in different host minerals. Most of the light rare earths (LREE) are present as the essential structural constituents of LREE fluorocarbonates such bastnaesite and synchysite, or in phosphates such as florencite and monazite. Yttrium and the heavy rare earths (HREE) occur mostly as minor concentrations in the form of cation substitutions within uranium minerals such as uraninite and coffinite, as well as brannerite to a lesser extent. Selective dissolution of uraninite and coffinite during acid leaching leads to the liberation of yttrium and HREE from their host minerals, resulting in higher percentage extractions of HREE than LREE in uranium bearing leach liquors. LREE liberation is more restricted because only the synchysite dissolves to any significant extent, while bastnaesite is more difficult to dissolve. 9 refs., 2 figs

  8. Rapid analysis of some rare earth magnets

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  9. Coprecipitation of rare earth elements with hydroxyapatite

    International Nuclear Information System (INIS)

    Fujino, Osamu

    1979-01-01

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

  10. Rare earths: harvesting basic research for technology

    International Nuclear Information System (INIS)

    Jagatap, B.N.

    2014-01-01

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

  11. Rapid analysis of some rare earth magnets

    Energy Technology Data Exchange (ETDEWEB)

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

    1978-12-01

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

  12. Thermogravimetric study of rare earth concentrates

    International Nuclear Information System (INIS)

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

    1974-01-01

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

  13. 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.

  14. 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

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

    International Nuclear Information System (INIS)

    Wong, T.; Seuntjens, J.M.

    1997-01-01

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

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

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

    Science.gov (United States)

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

    2015-04-21

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

  18. Nuclear orientation on rare earth nickel alloys

    International Nuclear Information System (INIS)

    Nishimura, K.

    1998-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

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

  20. Heavy Metal Stars

    Science.gov (United States)

    2001-08-01

    thereafter dies as a burnt-out, dim "white dwarf" . Stars with masses between 0.8 and 8 times that of the Sun are believed to evolve to AGB-stars and to end their lives in this particular way. At the same time, they produce beautiful nebulae like the "Dumbbell Nebula". Our Sun will also end its active life this way, probably some 7 billion years from now. Low-metallicity stars The detailed understanding of the "s-process" and, in particular, where it takes place inside an AGB-star, has been an area of active research for many years. Current state-of-the-art computer-based stellar models predict that the s-process should be particularly efficient in stars with a comparatively low content of metals ("metal-poor" or "low-metallicity" stars) . In such stars - which were born at an early epoch in our Galaxy and are therefore quite old - the "s-process" is expected to effectively produce atomic nuclei all the way up to the most heavy, stable ones, like Lead (atomic number 82 [2]) and Bismuth (atomic number 83) - since more neutrons are available per Iron-seed nucleus when there are fewer such nuclei (as compared to the solar composition). Once these elements have been produced, the addition of more s-process neutrons to those nuclei will only produce unstable elements that decay back to Lead. Hence, when the s-process is sufficiently efficient, atomic nuclei with atomic numbers around 82, that is, the Lead region, just continue to pile up. As a result, when compared to stars with "normal" abundances of the metals (like our Sun), those low-metallicity stars should thus exhibit a significant "over-abundance" of those very heavy elements with respect to Iron, in particular of Lead . Looking for Lead Direct observational support for this theoretical prediction would be the discovery of some low-metallicity stars with a high abundance of Lead. At the same time, the measured amounts of all the heavy elements and their relative abundances would provide very valuable information and

  1. Solvent Extraction of Rare Earths by Di-2 Ethylhexyl Phosphoric Acid

    International Nuclear Information System (INIS)

    Srinuttrakul, Wannee; Kranlert, Kannika; Kraikaew, Jarunee; Pongpansook, Surasak; Chayavadhanangkur, Chavalek; Kranlert, Kannika

    2004-10-01

    Solvent extraction has been widely applied for individual rare earth separation because the separation time is rapid and a large quantity of products is obtained. In this work, this technique was utilized to extract mixed rare earths, obtained from monazite digestion process. Di-2-ethylhexyl phosphoric acid (D2EHPA) was used as an extractant. The factors affected the extraction including HNO 3 concentration in mixed rare earth nitrate solution and the amount of D2EHPA were studied. The appropriate concentrations of HNO 3 and D2EHPA were found to be 0.01 and 1.5 M, respectively. From the result of equilibrium curve study, it was observed that heavy rare earths were extracted more efficient than light rare earths. A 6-stage continuous countercurrent solvent extraction was simulated for rare earth extraction. The optimum ratio of solvent to feed solution (S/F) was 2. Because of the high cost of D2EHPA, 1.0 M of D2EHPA was suitable for the rare earth extraction by the continuous countercurrent solvent extraction

  2. Application of 241Am EDXRF to the determination of rare earth samples of solvent extraction processes

    International Nuclear Information System (INIS)

    Yan Chunhua; Jia Jiangtao; Liao Chunsheng; Li Biaoguo

    1998-01-01

    A rapid energy dispersive X-ray fluorescence spectroscopy (EDXRF) analysis system is established to determine rare earth concentrations. The characteristic K-shell series X-rays of rare earths were excited by a 1.1 x 10 9 Bq 241 Am radioisotope source. The spectra were recorded and analyzed using a multi-channel analyzer, employing a high-purity Ge detector. In this method, the Compton scattering peak, absorption of elements, and specific simplification are considered. Samples of light, middle and heavy rare earths during separation processes in both hydrochloride solution and rare earth loaded organic phases were analyzed off-line. Some comparative results measured by ICP are also given. The results show that the method can be used for a wide range of rare earth concentrations (0.1-300 g l -1 rare earth oxide). Being rapid, effective, precise and non-destructive, the method can be applied to on-line analysis to determine rare earth concentrations during separation by solvent extraction. (orig.)

  3. 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...

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

    Indian Academy of Sciences (India)

    Unknown

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

  5. Ultrasonic attenuation in rare-earth monoarsenides

    Indian Academy of Sciences (India)

    2015-11-27

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

  6. Rare earth oxyhalogenide base thermoluminescent material

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1976-01-01

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

  7. Cerium and rare earth separation process

    International Nuclear Information System (INIS)

    Martin, M.; Rollat, M.

    1986-01-01

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

  8. Lifetime measurements of the rare earths

    International Nuclear Information System (INIS)

    Stahnke, H.J.

    1981-01-01

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

  9. Rare earth phosphors and phosphor screens

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  10. Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

    OpenAIRE

    Bogart, Justin A.; Cole, Bren E.; Boreen, Michael A.; Lippincott, Connor A.; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J.

    2016-01-01

    Rare earth metals, La���Lu, Sc, and Y, are essential components of electronic materials and permanent magnets in diverse technologies. But, their mining and separations chemistry are unsustainable and plagued with supply problems. Recycling of consumer materials containing rare earths is a promising new source of these critical materials but similarly requires efficient separations. We report the use of a tripodal hydroxylaminato ligand, TriNOx3���, with rare earth cations that enable fast, e...

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

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  12. Intra-group separation of rare earths using new organic phosphorus ligands

    International Nuclear Information System (INIS)

    Hadic, Sanela

    2017-01-01

    Rare earth elements (REE) have unique magnetic, photophysical, and chemical properties and they are therefore used in numerous high-technology applications. However, to this day, the isolation of pure rare earths from primary and secondary raw materials is very challenging. In this work, the hydrometallurgical separation of neighboring rare earths (e.g., praseodymium/ neodymium) was optimized with novel selective extraction agents. The separation of rare earths (yttrium and all lanthanides except promethium) was investigated with fourteen new organophosphorus compounds. Oxygen-bearing phosphinic acids yielded good separation results for heavy rare earths (dysprosium to lutetium). For light rare earths (lanthanum to neodymium), particularly high separation factors were realized with synergistic systems containing an aromatic dithiophosphinic acid and a co-extractant, such as tris (2-ethylhexyl) phosphate (TEHP). Optimization studies of the latter extraction system revealed an extremely high separation factor (SF) of 4.21 between praseodymium and neodymium. Another focus of this work was to understand the extraction mechanism. With the aid of nuclear magnetic resonance spectroscopy ("1H-NMR) and time-resolved laser fluorescence spectroscopy (TRLFS), the complex stoichiometry of promising extraction systems was examined. Studies revealed a dependency between the selectivity for rare earths and the coordination number of the formed complexes. In addition, temperature-dependent extraction experiments were performed and thermodynamic data (ΔG, ΔH, and ΔS) determined. These data provided additional information about the origin of selectivity for neighboring rare earths. With regard to the industrial capability of the investigated extraction systems, the chemical durability of ligands was studied under process-relevant conditions. Qualitative and quantitative analytical methods (e.g., GC-MS) were used in long-term experiments to determine the ligand degradation. After

  13. Reduced temperature phase diagrams of the silver-rare earths binary systems

    International Nuclear Information System (INIS)

    Ferro, R.; Delfino, S.; Capelli, R.; Borsese, A.

    1975-01-01

    Phase equilibria of the silver-rare earth binary systems have been reported in ''reduced temperature'' diagrams (the ''reduced temperature'' being defined as the ratio between a characteristic temperature of the Agsub(x)R.E. phase and the melting temperature of the corresponding R.E. metal, both in 0 K). The smooth trends of the various characteristic reduced temperatures, when plotted against the R.E. atomic number, have been demonstrated. On passing from the light- to the heavy-rare-earths, a correlation has been found between the crossing of these curves and other phenomena, such as the disappearing of the Ag 5 R.E. phases from incongruently, to congruently melting compounds. The trends of the reduced-temperature curves have been briefly discussed in terms of the treatment suggested by Gschneidner together with the volumetric data known for the different Agsub(x)R.E. phases. In addition, the characteristic data of the 1:1 AgR.E. compounds have been compared with those of the analogous AuR.E. phases. (Auth.)

  14. 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.

  15. Pilot-scale recovery of rare earths and scandium from phosphogypsum and uranium leachates

    Directory of Open Access Journals (Sweden)

    Mashkovtsev Maxim

    2016-01-01

    Full Text Available Ural Federal University (UrFU and VTT have performed joint research on development of industrial technologies for the extraction of REM and Scandium compounds from phosphogypsum and Uranium ISL leachate solutions. Leaching-absorption experiments at UrFU have been supported with multicomponent solution modelling by VTT. The simulations have been performed with VTT’s ChemSheet/Balas program and can be used for speciation calculations in the lixiviant solution. The experimental work combines solvent extraction with advanced ion exchange methodology in a pilot facility capable of treating 5 m3 solution per hour. Currently, the plant produces cerium carbonate, lanthanum oxide, neodymium oxide and concentrate of heavy rare earth metals. A batch of 45 t solids has been processed with the gain of 100 kg’s of REM concentrate. A mini-pilot plant with productivity above 50 liters per hour has been applied to recover scandium oxide and REE concentrates from the uranium ISL solution. As the preliminary product contains radioactivity (mainly strontium, an additional decontamination and cleaning of both concentrates by extraction has rendered a necessity. Finally a purified 99% concentrate of scandium oxide as well as 99% rare earth concentrate are received.

  16. Distribution of rare earth elements in an alluvial aquifer affected by acid mine drainage: the Guadiamar aquifer (SW Spain)

    International Nuclear Information System (INIS)

    Olias, M.; Ceron, J.C.; Fernandez, I.; Rosa, J. de la

    2005-01-01

    This work analyses the spatial distribution, the origin, and the shale-normalised fractionation patterns of the rare earth elements (REE) in the alluvial aquifer of the Guadiamar River (south-western Spain). This river received notoriety in April 1998 for a spill that spread a great amount of slurry (mainly pyrites) and acid waters in a narrow strip along the river course. Groundwaters and surface waters were sampled to analyse, among other elements, the REEs. Their spatial distribution shows a peak close to the mining region, in an area with low values of pH and high concentrations of sulphates and other metals such as Zn, Cu, Co, Ni, Pb, and Cd. The patterns of shale-normalised fractionation at the most-contaminated points show an enrichment in the middle rare earth elements (MREE) with respect to the light (LREE) and heavy (HREE) ones, typical of acid waters. The Ce-anomaly becomes more negative as pH increases, due to the preferential fractionation of Ce in oxyhydroxides of Fe. - Pollution of the aquifer with rare earth elements is documented at a site of a major spill from a mining operation

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

    Science.gov (United States)

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-07-01

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China's supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructed a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the US market starting from 2018. Results showed that market share of the illegal sector has grown since 2007-2015, ranging between 22% and 25% of China's rare earth supply, translating into 59-65% illegal heavy rare earths and 14-16% illegal light rare earths. There will be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Finally, we illustrate revenue streams for different ore compositions in China in 2015.

  18. Magnetic fluctuations in heavy-fermion metals

    DEFF Research Database (Denmark)

    Mason, T.E.; Petersen, T.; Aeppli, G.

    1995-01-01

    Elastic and inelastic neutron scattering have been used to study the antiferromagnetic ordering and magnetic excitations of the U heavy-fermion superconductors UPd2Al3 and URu2Si2 above and below T-N. While both materials exhibit the coexistence of superconductivity and antiferromagnetic order......, the nature of the antiferromagnetic order and magnetic fluctuations is qualitatively quite different. UPd2Al3 resembles a rare earth magnetic system with coupling of the 4f electrons to the conduction electrons manifested in a broadening of otherwise conventional spin wave excitations. This is in marked...

  19. Effects of Rare Earth on the Microstructure and Impact Toughness of H13 Steel

    OpenAIRE

    Gao, Jinzhu; Fu, Paixian; Liu, Hongwei; Li, Dianzhong

    2015-01-01

    Studies of H13 steel suggest that under appropriate conditions, additions of rare-earth metals (REM) can significantly enhance mechanical properties, such as impact toughness. This improvement is apparently due to the formation of finer and more dispersive RE inclusions and grain refinement after REM additions. In this present work, the microstructure evolution and mechanical properties of H13 steel with rare earth additions (0, 0.015, 0.025 and 0.1 wt.%) were investigated. The grain size, ...

  20. Batch Simulation of Rare Earths Extractive Separation by Di (2-Ethylhexyl) Phosphoric Acid and Tributylphosphate in Kerosene

    International Nuclear Information System (INIS)

    Kraikaew, Jarunee; Srinuttakul, Wanee

    2004-01-01

    Liquid-liquid extraction is applied to separate individual rare earths. In this research, 6-stage continuous countercurrent solvent extraction was simulated to extract rare earths from rare earth nitrate solution, which was obtained from monazite processing, to estimate the possible optimum operating conditions for pilot or industrial plants. The solvent(S) per feed(F) ratio (S/F) was varied from 1 to 3. The organic are 1.0 and 1.5 Molars (M) Di (2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene. 50% tributylphosphate (TBP) in kerosene was applied for comparison. It was found that D2EHPA was a good extracting agent for heavy rare earths while TBP extracted well both light and heavy rare earths. After extraction with TBP and D2EHPA, the extraction efficiency at solvent per feed ratio (S/F) =2 and 3 showed a slight difference. S/F =2 was selected commercially for operation

  1. Thermal decomposition of heavy rare-earth butanoates, Ln(C3H7CO2)3 (Ln = Er, Tm, Yb and Lu) in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao

    2016-01-01

    was observed in all four compounds, but its course depends on the rare-earth element. Decomposition to sesquioxides proceeds via the formation of dioxymonocarbonates (Ln2O2CO3) and release of 4-heptanone (C3H7COC3H7) as well as carbon dioxide (CO2) without evidence for an intermediate oxobutanoate stage...... of Ln2O2CO3 and Ln2O3. The stability of this intermediate state seems to decrease with the mass of the rare-earth elements. Complete conversion to Ln2O3 is reached at about 1100 °C. The overall thermal decomposition behaviour of the title compounds is different from previous reports for other rare....... During the decomposition of Ln2O2CO3 into the respective sesquioxides (Ln2O3), an intermediate plateau extending from approximately 550 to 850 °C appears in the TG traces. The overall composition during this stage corresponds approximately to Ln2O2.8(CO3)0.2, but the state is more probably a mixture...

  2. Proceedings of the national conference on rare earth processing and utilization - 2014: abstracts

    International Nuclear Information System (INIS)

    Anitha, M.; Dasgupta, Kinshuk; Singh, D.K.

    2014-01-01

    The rare earth elements (REEs) are becoming increasingly important in the transition to a low-carbon, circular economy, considering their essential role in permanent magnets, lamp phosphors, rechargeable nickel metal hydride batteries and catalysts and other green applications. The increasing popularity of hybrid and electric cars, wind turbines and compact fluorescent lamps is causing an increase in the demand and price of REEs. The European Commission considers the REEs as the most critical raw materials group, with the highest supply risk. According to the medium-term criticality matrix of the U.S. Department of Energy (DOE), the five most critical REEs are neodymium (Nd), europium (Eu), terbium (Tb), dysprosium (Dy) and yttrium (Y). China is presently producing more than 90% of all rare earths, although they possess less than 40% of the proven reserves. Due to large and increasing domestic demands, China tightened its REE export quota from 2012 onwards. These export quotas caused serious problems for REE users outside of China. To tackle the REE supply challenge, several approaches have been proposed. Fortunately India is blessed with large resources of rare earths in the form of monazite found in the beach sands of Kerala, Tamil Nadu and Odisha. Indian Rare Earths Limited at Aluva near Kochi used to produce mainly mixed rare earths chloride and export to USA, UK, France, Japan, etc. During the 1990s and early 2000s this plant exported pure oxides of samarium, neodymium, etc. to developed countries. This national conference has expanded its canvas by including newer emerging areas in rare earths recycling, environmental issues, recent advances in rare earth material science, rare earth research and development initiatives around the world which provide a platform for the growth of rare earth Industry. Papers relevant to INIS are indexed separately

  3. Organic Waste Composts, a Serious Rare- Earth Source as Determined by Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Sroor, A.; El-Bahi, S.M.; Abdel-Halieem, A.S.; Abdel-Sabour, M.F.

    1999-01-01

    Delayed Neutron Activation Analysis technique [DNNA] was applied for investigating rare-earth elements and some heavy metals content of some locally organic fertilizers namely cattle manure (CM) , dried sewage sludge [SS] , municipal solid waste [MSW] and mixture for a (SS+MSW). The γ-ray spectrum of each sample was investigated using a HPGe detector equipped with computer unit. Fourteen elements were determined. Some of them were confirmed by the γ-γ cascades using a HPGe-HPGe coincidence spectrometer. The concentration of these elements in each sample was measured in μg/g. Some of these elements may lead to undesirable environmental effects. The undiscriminating use of organic waste as organic fertilizers may result in the increase of toxic elements [Cr, Sc, Sb, Th, etc.) in soil environment which may transfer through food chain to human health

  4. Rare earth oxide doping in oxide cathodes

    International Nuclear Information System (INIS)

    Engelsen, Daniel den; Gaertner, Georg

    2006-01-01

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

  5. Fascinating world of rare earth research

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.

    1977-01-01

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

  6. Diagnostic study about lanthanides (rare earths)

    International Nuclear Information System (INIS)

    Ribeiro, G.F.

    1985-01-01

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

  7. Mineralogy of the rare earth elements

    International Nuclear Information System (INIS)

    Clark, A.M.

    1984-01-01

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

  8. Structure of small rare earth clusters

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  9. Atomic masses of rare-earth isotopes

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  10. Epitaxial rare-earth superlattices and films

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  11. Leach of the weathering crust elution-deposited rare earth ore for low environmental pollution with a combination of (NH4)2SO4 and EDTA.

    Science.gov (United States)

    Tang, Jie; Qiao, Jiyang; Xue, Qiang; Liu, Fei; Chen, Honghan; Zhang, Guochen

    2018-05-01

    High concentration of ammonium sulfate, a typical leaching agent, was often used in the mining process of the weathering crust elution-deposited rare earth ore. After mining, a lot of ammonia nitrogen and labile heavy metal fractions were residual in tailings, which may result in a huge potential risk to the environment. In this study, in order to achieve the maximum extraction of rare earth elements and reduce the labile heavy metal, extraction effect and fraction changes of lanthanum (La) and lead (Pb) in the weathering crust elution-deposited rare earth ore were studied by using a compound agent of (NH 4 ) 2 SO 4 -EDTA. The extraction efficiency of La was more than 90% by using 0.2% (NH 4 ) 2 SO 4 -0.005 M EDTA, which was almost same with that by using 2.0% (NH 4 ) 2 SO 4 solution. In contrast, the extraction efficiency of Pb was 62.3% when use 0.2% (NH 4 ) 2 SO 4 -0.005 M EDTA, which is much higher than that (16.16%) achieved by using 2.0% (NH 4 ) 2 SO 4 solution. The released Pb fractions were mainly acid extractable and reducible fractions, and the content of reducible fraction being leached accounted for 70.45% of the total reducible fraction. Therefore, the use of 0.2% (NH 4 ) 2 SO 4 -0.005 M EDTA can not only reduce the amount of (NH 4 ) 2 SO 4 , but also decrease the labile heavy metal residues in soil, which provides a new way for efficient La extraction with effective preventing and controlling environmental pollution in the process of mining the weathering crust elution-deposited rare earth ore. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Separation of rare earth by column chromatography using organic resins XAD/DEPHA

    International Nuclear Information System (INIS)

    Zini, J.; Ferreira, J.C.; Bergamaschi, V.S.; Santos, I.; Carvalho, F.M.S.

    2013-01-01

    The designation of light and heavy rare earth was used the fractionation used in separation processes. In this study the process of separation of rare earth, in groups, by chromatographic column consisting in fixing of cations these elements in an organic resin Amberlite XAD16 functionalized with the extracting agent DEPHA and another portion functionalized with a mixture of extractors DEPHA/TOP. The preparation of these resins was performed in two forms, one directly as the extracting agent to the resin and the other to be used in ethyl alcohol. Conditioned resins were introduced in chromatographic columns in separation of groups, light and heavy, using a standard solution of cerium nitrate and standard solution of holmium nitrate groups to represent light and heavy respectively. The characterization technique used to identify the rare earth elements was Spectrometry X-Ray Fluorescence (XRF). The results using the technique of chromatography were satisfactory, obtaining 100% separation of the elements. (author)

  13. Separation of rare earth by column chromatography using organic resins XAD/DEPHA

    Energy Technology Data Exchange (ETDEWEB)

    Zini, J.; Ferreira, J.C.; Bergamaschi, V.S.; Santos, I.; Carvalho, F.M.S., E-mail: jcferrei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CCCH/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Celulas a Combustivel e Hidrogenio

    2013-07-01

    The designation of light and heavy rare earth was used the fractionation used in separation processes. In this study the process of separation of rare earth, in groups, by chromatographic column consisting in fixing of cations these elements in an organic resin Amberlite XAD16 functionalized with the extracting agent DEPHA and another portion functionalized with a mixture of extractors DEPHA/TOP. The preparation of these resins was performed in two forms, one directly as the extracting agent to the resin and the other to be used in ethyl alcohol. Conditioned resins were introduced in chromatographic columns in separation of groups, light and heavy, using a standard solution of cerium nitrate and standard solution of holmium nitrate groups to represent light and heavy respectively. The characterization technique used to identify the rare earth elements was Spectrometry X-Ray Fluorescence (XRF). The results using the technique of chromatography were satisfactory, obtaining 100% separation of the elements. (author)

  14. 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...

  15. Investigating Rare Earth Element Systematics in the Marcellus Shale

    Science.gov (United States)

    Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.

    2014-12-01

    The lanthanide series of elements (the 14 rare earth elements, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 μg/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our

  16. CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2}. A new rare-earth metal(III) fluoride oxoselenate(IV) with sections of the ReO{sub 3}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, Stefan; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany)

    2017-09-04

    A new representative of rare-earth metal(III) fluoride oxoselenates(IV) derivatized with alkali metals could be synthesized via solid-state reactions. Colorless single crystals of CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2} were obtained through the reaction of Sc{sub 2}O{sub 3}, ScF{sub 3}, and SeO{sub 2} (molar ratio 1:1:3) with CsBr as reactant and fluxing agent. For this purpose, corundum crucibles embedded as liners into evacuated silica ampoules were applied as containers for these reactions at 700 C for seven days. The new quintenary compound crystallizes in the trigonal space group P3m1 with a = 565.34(4) and c = 1069.87(8) pm (c/a = 1.892) for Z = 1. The crystal structure of CsSc{sub 3}F{sub 6}[SeO{sub 3}]{sub 2} contains two crystallographically different Sc{sup 3+} cations. Each (Sc1){sup 3+} is surrounded by six fluoride anions as octahedron, while the octahedra about (Sc2){sup 3+} are formed by three fluoride anions and three oxygen atoms from three terminal [SeO{sub 3}]{sup 2-} anions. The [(Sc1)F{sub 6}]{sup 3-} octahedra link via common F{sup -} vertices to six fac-[(Sc2)F{sub 3}O{sub 3}]{sup 6-} octahedra forming {sup 2}{sub ∞}{[Sc_3F_6O_6]"9"-} layers parallel to (001). These layers are separated by oxygen-coordinated Cs{sup +} cations (C.N. = 12), arranging for the charge compensation, while Se{sup 4+} cations within the layers surrounded by three oxygen atoms as ψ{sup 1}-tetrahedral [SeO{sub 3}]{sup 2-} units complete the structure. EDX measurements confirmed the composition of the title compound and single-crystal Raman studies showed the typical vibrational modes of isolated [SeO{sub 3}]{sup 2-} anions with ideal C{sub 3v} symmetry. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. The electrorheological properties of nano-sized SiO2 particle materials doped with rare earths

    International Nuclear Information System (INIS)

    Liu Yang; Liao Fuhui; Li Junran; Zhang Shaohua; Chen Shumei; Wei Chenguan; Gao Song

    2006-01-01

    Electrorheological (ER) materials of pure SiO 2 and SiO 2 doped with rare earths (RE = Ce, Gd, Y) (non-metallic glasses (silicates)) were prepared using Na 2 SiO 3 and RECl 3 as starting materials. The electrorheological properties are not enhanced by all rare earth additions. The material doped with Ce exhibits the best ER performance

  18. Electro-kinetic separation of rare earth elements using a redox-active ligand

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Huayi; Cole, Bren E.; Qiao, Yusen; Bogart, Justin A.; Cheisson, Thibault; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA (United States)

    2017-10-16

    Purification of rare earth elements is challenging due to their chemical similarities. All of the deployed separation methods rely on thermodynamic properties, such as distribution equilibria in solvent extraction. Rare-earth-metal separations based on kinetic differences have not been examined. Herein, we demonstrate a new approach for rare-earth-element separations by exploiting differences in the oxidation rates within a series of rare earth compounds containing the redox-active ligand [{2-(tBuN(O))C_6H_4CH_2}{sub 3}N]{sup 3-}. Using this method, a single-step separation factor up to 261 was obtained for the separation of a 50:50 yttrium-lutetium mixture. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. The Effect of Rare Earth on the Structure and Performance of Laser Clad Coatings

    Science.gov (United States)

    Bao, Ruiliang; Yu, Huijun; Chen, Chuanzhong; Dong, Qing

    Laser cladding is one kind of advanced surface modification technology and has the abroad prospect in making the wear-resistant coating on metal substrates. However, the application of laser cladding technology does not achieve the people's expectation in the practical production because of many defects such as cracks, pores and so on. The addiction of rare earth can effectively reduce the number of cracks in the clad coating and enhance the coating wear-resistance. In the paper, the effects of rare earth on metallurgical quality, microstructure, phase structure and wear-resistance are analyzed in turns. The preliminary discussion is also carried out on the effect mechanism of rare earth. At last, the development tendency of rare earth in the laser cladding has been briefly elaborated.

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

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  1. Rare earth elements as a by-catch of sedimentary deposits. Exploration program of rare earth elements; Selten Erd Elemente als Beifang sedimentaerer Lagerstaetten. Erkundungsprogramm Selten Erd Elemente

    Energy Technology Data Exchange (ETDEWEB)

    Linhardt, E.; Gebhardt, A. (comps.)

    2014-02-15

    The increasing demand for rare earth elements (REE) in the field of ''green technologies'' on the one hand and the shortage of raw materials on the world markets on the other hand confronted also Bavaria as an industrial location with growing supply problems in these ''high tech raw materials''. The aim of exploration was the clarification of the feedstock REE potential of heavy mineral concentrates which are obtained in the industrial extraction and processing of sand and kaolin in existing extraction operations in northern Bavaria as by catch and are potentially winnable or marketable. The in-depth investigation enabled the potential of found rare earth elements and other high-tech metal oxides that can be classified as very likely find it in terms of an economic recovery. [German] Der zunehmende Bedarf an Selten Erd Elementen (SEE) im Bereich der ''Gruenen Technologien'' zum Einen sowie die Rohstoffverknappung auf den Weltmaerkten zum Anderen konfrontiert auch Bayern als Industriestandort mit wachsenden Versorgungsproblemen bei diesen ''high tech-Grundstoffen''. Ziel der Erkundung war die Klaerung des rohstofflichen SEE-Potenzials von Schwermineralkonzentraten, die bei der grosstechnischen Gewinnung und Aufbereitung von Sand und Kaolin in vorhandenen Gewinnungsbetrieben Nordbayerns als Beifang anfallen und potenziell gewinn- bzw. vermarktbar sind. Im Zuge der Untersuchung konnten nutzbare Potenziale von Selten Erd Elementen und anderen high-tech - Metalloxiden gefunden werden, die sehr wahrscheinlich als fuendig im Hinblick auf eine wirtschaftliche Gewinnung eingestuft werden koennen.

  2. 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.

  3. Preparation of rare earth fluorides from apatite concentrate

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  4. The flotation of rare earths - a contribution to industrial hygiene

    International Nuclear Information System (INIS)

    Andrews, W.H.; Collins, D.N.; Hollick, C.T.

    1990-01-01

    Conventional processing of heavy mineral deposits containing radioactive rare earth minerals such as monazite and xenotime may cause industrial hygiene problems through atmospheric dust and contamination of product concentrates. An alternative procedure has been developed by Wimmera Industrial Mineral Pty. Ltd. at the Drung South deposit in Victoria. The radioactive minerals are removed from bulk heavy mineral concentrates by flotation with little loss of other economic minerals. With fine ores, recoveries of over 95% have been achieved and with coarse ores over 80%. The potential for generation of radioactive dust or product contamination in subsequent processing is correspondingly reduced. Several flotation regimes, which have proven effective are discussed. 7 refs., 7 tabs., 1 fig

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  6. Process for removing heavy metal compounds from heavy crude oil

    Science.gov (United States)

    Cha, Chang Y.; Boysen, John E.; Branthaver, Jan F.

    1991-01-01

    A process is provided for removing heavy metal compounds from heavy crude oil by mixing the heavy crude oil with tar sand; preheating the mixture to a temperature of about 650.degree. F.; heating said mixture to up to 800.degree. F.; and separating tar sand from the light oils formed during said heating. The heavy metals removed from the heavy oils can be recovered from the spent sand for other uses.

  7. Air Pollution with Heavy Metals and Radionuclides in Slovakia Studied by the Moss Biomonitoring Technique

    CERN Document Server

    Florek, M; Mankovska, B; Oprea, K; Pavlov, S S; Steinnes, E; Sykora, I

    2001-01-01

    Applying the moss biomonitoring technique to air pollution studies in Slovakia, heavy metals, rare-earth elements, actinides (U and Th) were determined in 86 moss samples from the European moss survey 2000 by means of epithermal neutron activation analysis at the IBR-2 reactor (Dubna). Such elements as In, Cu, Cd, Hg and Pb were determined by AAS in the Forest Research Institute, Zvolen (Slovakia). The results of measurement of the natural radionuclides ^{210}Pb, ^{7}Be, ^{137}Cs and ^{40}K in 11 samples of moss are also reported. A comparison with the results from moss surveys 1991 and 1995 revealed previously unknown tendencies of air pollution in the examined areas.

  8. Rare earth elements materials production from apatite ores

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  9. Rare earth permanent magnet with easy magnetization

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  10. Port Pirie rare earths plant stage 3

    International Nuclear Information System (INIS)

    1990-08-01

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

  11. Luminescence studies of rare earth doped dosimeters

    International Nuclear Information System (INIS)

    Karali, T.

    1999-10-01

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

  12. Alternative value chains for rare earths

    DEFF Research Database (Denmark)

    Machacek, Erika; Fold, Niels

    2014-01-01

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

  13. Heavy metals in Mindhola river estuary, India

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Rokade, M.A; Mandalia, A

    The heavy metal concentrations are studied along the Mindhola river estuary. Surface and bottom water samples were collected using Niskin Sampler. The sediment samples were collected using a Van Veen grab. The heavy metal concentration is estimated...

  14. Gaps and pseudogaps in perovskite rare earth nickelates

    Directory of Open Access Journals (Sweden)

    S. James Allen

    2015-06-01

    Full Text Available We report on tunneling measurements that reveal the evolution of the quasiparticle state density in two rare earth perovskite nickelates, NdNiO3 and LaNiO3, that are close to a bandwidth controlled metal to insulator transition. We measure the opening of a sharp gap of ∼30 meV in NdNiO3 in its insulating ground state. LaNiO3, which remains a correlated metal at all practical temperatures, exhibits a pseudogap of the same order. The results point to both types of gaps arising from a common origin, namely, a quantum critical point associated with the T = 0 K metal-insulator transition. The results support theoretical models of the quantum phase transition in terms of spin and charge instabilities of an itinerant Fermi surface.

  15. ICP-AES determination of rare earths in zirconium with prior chemical separation of the matrix

    International Nuclear Information System (INIS)

    Rajeswari, B.; Dhawale, B.A.; Page, A.G.; Sastry, M.D.

    2002-01-01

    Zirconium being one of the most important material in nuclear industry used as a fuel cladding in reactors and an additive in advanced fuels necessitates its characterization for trace metallic contents. Zirconium, as refractory in nature as the rare earth elements, has a complex spectrum comprising of several emission lines. Rare earths, which are high neutron absorbers have to be analysed at very low limits. Hence, to achieve the desired limits, the major matrix has to be separated prior to rare earth determination. The present paper describes the method developed for the separation of rare earths from zirconium by solvent extraction using Trioctyl Phosphine Oxide (TOPO) as the extractant followed by their determination using Inductively Coupled Plasma - Atomic Emission Spectrometric (ICP-AES) method. Initially, radiochemical studies were carried out using known amounts of gamma active tracers of 141 Ce, 152-154 Eu, 153 Gd and 95 Zr for optimisation of extraction conditions using Tl- activated NaI detector. The optimum conditions at 0.5 M TOPO/xylene in 6 M HCl so as to achieve a quantitative recovery of rare earth analytes alongwith a near total extraction of zirconium in the organic phase, was further extended to carry out the studies using ICP-AES method. The recovery of rare earths was found to be quantitative within experimental error with a precision better than 10% RSD. (author)

  16. Investigation of the evaporation of rare earth chlorides in a LiCl-KCl molten salt

    International Nuclear Information System (INIS)

    Sung Bin Park; Dong Wook Cho; Moon Sik Woo; Sung Chan Hwang; Young Ho Kang; Jeong Guk Kim; Hansoo Lee

    2011-01-01

    Uranium dendrites which were deposited at a solid cathode of an electrorefiner contained a certain amount of salts. These salts should be removed for the recovery of pure metal using a cathode processor. In the uranium deposits from the electrorefining process, there are actinide chlorides and rare earth chlorides in addition to uranium chloride in the LiCl-KCl eutectic salt. The evaporation behaviors of the actinides and rare earth chlorides in the salts should be investigated for the removal of salts in the deposits. Experiments on the salt evaporation of rare earth chlorides in a LiCl-KCl eutectic salt were carried out. Though the vapor pressures of the rare earth chlorides were lower than those of the LiCl and KCl, the rare earth chlorides were co-evaporized with the LiCl-KCl eutectic salt. The Hertz-Langmuir relation was applied for this evaporation, and also the evaporation rates of the salt were obtained. The co-evaporation of the rare earth chlorides and LiCl-KCl eutectic were also discussed. (author)

  17. Study of rare earth elements as material for control rods

    International Nuclear Information System (INIS)

    1975-03-01

    The properties of rare earth elements as the material for control rods were studied. The rare earth elements, especially europium oxide, has the nuclear property corresponding to boron carbide, and its neutron absorption process does not emit alpha particles. The elements produced as a result of neutron capture also have large capture cross sections. This paper presents survey report on the properties and nuclear properties of rare earth elements, and comparison with other materials. Preliminary experiment was performed to make the pellets of europium oxide, and is described in this paper. Because of large density, the crystal form to be made was monoclinic system. Europium hydroxide was decomposed at 1000 0 C and 10 -5 torr. The obtained powder was dipped into benzene, and dryed in the air at 450 0 C. This powder was pressed and sintered in the air for one hour at 1500 0 C. The density of the obtained pellets was 97.0% of the theoretical density. The cross section of europium for fast neutron absorption is not yet accurately obtained, and is in the range between 4.65 and 8.5 barn for 151 Eu(n,γ) reaction. Since chain absorption reaction is caused in Eu, the overall capability of neutron absorption is not much changed by the loss of original material due to absorption. The pellets of europium oxide may be handled in air, but must be kept in dry atmosphere. The reactions of europium oxide with various metals were also investigated. The characteristic behavior in case of irradiation depends on the amount of silicon contained, and it was very good if the amount was less than 0.03%. (Kato, T.)

  18. Monazite upgradation and production of high pure rare earths

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  19. Magnetoelastic interaction in rare earth systems

    International Nuclear Information System (INIS)

    Dohm, V.

    1975-01-01

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

  20. Costs and benefits of rare earth screens

    International Nuclear Information System (INIS)

    Taylor, F.E.

    1977-01-01

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